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1

The harmonic oscillator and nuclear physics  

NASA Technical Reports Server (NTRS)

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.

Rowe, D. J.

1993-01-01

2

Data Compression and Harmonic Analysis  

Microsoft Academic Search

In this paper we review some recent interactions between harmonic analysis and data compression. The story goes back of course to Shannon's theory in the case of Gaussian stationary processes, which says that transforming into a Fourier basis followed by block coding gives an optimal lossy compression technique; practical developments like transform- based image compression have been inspired by this

David L. Donoho; Martin Vetterli; Ronald A. Devore; Ingrid Daubechies

1998-01-01

3

Harmonic Analysis on Quantum Tori  

NASA Astrophysics Data System (ADS)

This paper is devoted to the study of harmonic analysis on quantum tori. We consider several summation methods on these tori, including the square Fejér means, square and circular Poisson means, and Bochner-Riesz means. We first establish the maximal inequalities for these means, then obtain the corresponding pointwise convergence theorems. In particular, we prove the noncommutative analogue of the classical Stein theorem on Bochner-Riesz means. The second part of the paper deals with Fourier multipliers on quantum tori. We prove that the completely bounded L p Fourier multipliers on a quantum torus are exactly those on the classical torus of the same dimension. Finally, we present the Littlewood-Paley theory associated with the circular Poisson semigroup on quantum tori. We show that the Hardy spaces in this setting possess the usual properties of Hardy spaces, as one can expect. These include the quantum torus analogue of Fefferman's H1-BMO duality theorem and interpolation theorems. Our analysis is based on the recent developments of noncommutative martingale/ergodic inequalities and Littlewood-Paley-Stein theory.

Chen, Zeqian; Xu, Quanhua; Yin, Zhi

2013-09-01

4

Harmonic Analysis of the Output Voltage of a Third-Harmonic-Injected Inverter for LSM Drives  

NASA Astrophysics Data System (ADS)

The superconducting magnetic levitation railway system (MAGLEV) under development in Japan uses a pulse-width-modulation (PWM) inverter for driving a linear synchronous motor (LSM). The inverter output voltage contains non-negligible harmonics which cause harmonic resonances in the LSM system, and therefore harmonics of the output voltage have been analyzed in order to control such harmonic resonances. This paper applies a third-harmonic injection method to the inverter for the purpose of enhancing the output voltage without changing the circuit configuration. It performs harmonic analysis of the output voltage of the inverter based on the third-harmonic injection. Validity of the harmonic analysis is verified by computer simulation.

Shigeeda, Hidenori; Okui, Akinobu; Akagi, Hirofumi

5

Harmonic Analysis Can Assess Hydrologic Cumulative Impacts.  

National Technical Information Service (NTIS)

This note describes an aid for assessing cumulative impacts on wetlands. Harmonic analysis techniques are employed to reveal time frames when disruption to basic flow patterns may have occurred. Water-level patterns largely determine the nature of wetland...

1994-01-01

6

Venus topography - A harmonic analysis  

NASA Technical Reports Server (NTRS)

A model of Venusian global topography has been obtained by fitting an eighteenth-degree harmonic series to Pioneer Venus orbiter radar altimeter data. The mean radius is (6051.45 + or - 0.04) km. The corresponding mean density is (5244.8 + or 0.5) kg/cu m. The center of figure is displaced from the center of mass by (0.339 + or - 0.088) km towards (6.6 + or 10.1) deg N, (148. 8 + or - 7.7) deg. The figure of Venus is distinctly triaxial, but the orientation and magnitudes of the principal topographic axes correlate rather poorly with the gravitational principal axes. However, the higher-degree harmonics of topography and gravity are significantly correlated. The topographic variance spectrum of Venus is very similar in form to those of the moon, Mars, and especially earth. It is suggested that this spectral similarity simply reflects a statistical balance between constructional and degradational geomorphic proceses. Venus and earth are particularly similar (and differ from the moon and Mars) in that the larger bodies both exhibit a significant low degree deficit (relative to the extrapolated trend of the higher harmonics).

Bills, B. G.; Kobrick, M.

1985-01-01

7

Analysis of Harmonic and Inter-Harmonic Based on Hilbert-Huang Transform  

Microsoft Academic Search

To analyze harmonic and inter-harmonic accurately is significant to the stability of power system. The Hilbert-Huang transform (HHT) is adopted to analyze harmonic and interharmonic in order to overcome the shortcoming of FFT method and wavelet analysis method. The power quality signals are decomposed by empirical mode decomposition (EMD) method, and then a series of intrinsic mode function (IMF) are

Jianming Yu; Liang Yang

2009-01-01

8

Harmonic Analysis on Quantum Complex Hyperbolic Spaces  

NASA Astrophysics Data System (ADS)

In this paper we obtain some results of harmonic analysis on quantum complex hyperbolic spaces. We introduce a quantum analog for the Laplace-Beltrami operator and its radial part. The latter appear to be second order q-difference operator, whose eigenfunctions are related to the Al-Salam-Chihara polynomials. We prove a Plancherel type theorem for it.

Bershtein, Olga; Kolisnyk, Yevgen

2011-08-01

9

Physical modeling with orthotropic material based on harmonic fields.  

PubMed

Although it is well known that human bone tissues have obvious orthotropic material properties, most works in the physical modeling field adopted oversimplified isotropic or approximated transversely isotropic elasticity due to the simplicity. This paper presents a convenient methodology based on harmonic fields, to construct volumetric finite element mesh integrated with complete orthotropic material. The basic idea is taking advantage of the fact that the longitudinal axis direction indicated by the shape configuration of most bone tissues is compatible with the trajectory of the maximum material stiffness. First, surface harmonic fields of the longitudinal axis direction for individual bone models were generated, whose scalar distribution pattern tends to conform very well to the object shape. The scalar iso-contours were extracted and sampled adaptively to construct volumetric meshes of high quality. Following, the surface harmonic fields were expanded over the whole volumetric domain to create longitudinal and radial volumetric harmonic fields, from which the gradient vector fields were calculated and employed as the orthotropic principal axes vector fields. Contrastive finite element analyses demonstrated that elastic orthotropy has significant effect on simulating stresses and strains, including the value as well as distribution pattern, which underlines the relevance of our orthotropic modeling scheme. PMID:21570147

Liao, Sheng-Hui; Zou, Bei-Ji; Geng, Jian-Ping; Wang, Jin-Xiao; Ding, Xi

2012-11-01

10

The Orthosymplectic Lie Supergroup in Harmonic Analysis  

NASA Astrophysics Data System (ADS)

The study of harmonic analysis in superspace led to the Howe dual pair (O(m)×Sp(2n),sl2). This Howe dual pair is incomplete, which has several implications. These problems can be solved by introducing the orthosymplectic Lie supergroup OSp(m|2n). We introduce Lie supergroups in the supermanifold setting and show that everything is captured in the Harish-Chandra pair. We show the uniqueness of the supersphere integration as an orthosymplectically invariant linear functional. Finally we study the osp(m|2n)-representations of supersymmetric tensors for the natural module for osp(m|2n).

Coulembier, Kevin

2010-09-01

11

Harmonics  

NSDL National Science Digital Library

This simulation illustrates the behavior of standing waves in situation where one end fixed, both ends are fixed, and both ends are free. The simulation allows the user to examine the standing wave behavior at the fundamental frequency and when the first three harmonics are added. The user can control the amplitude of each of the harmonics and observe the resulting pattern.

Renault, Pascal

2009-01-22

12

Spherical harmonic analysis of earth's conductive heat flow  

Microsoft Academic Search

A reappraisal of the international heat flow database has been carried out and the corrected data set was employed in spherical harmonic analysis of the conductive component of global heat flow. Procedures used prior to harmonic analysis include analysis of the heat flow data and determination of representative mean values for a set of discretized area elements of the surface

V. M. Hamza; R. R. Cardoso; C. F. Ponte Neto

2008-01-01

13

Quantum channels arising from abstract harmonic analysis  

NASA Astrophysics Data System (ADS)

We present a new application of harmonic analysis to quantum information by constructing intriguing classes of quantum channels stemming from specific representations of multiplier algebras over locally compact groups G. Beginning with a representation of the measure algebra M(G), we unify and elaborate on recent counter-examples to a conjecture on the structure of fixed point subalgebras in infinite dimensions, as well as present an application to the noiseless subsystems method of quantum error correction. Using a representation of the completely bounded Fourier multiplier algebra McbA(G), we provide a new class of counter-examples to the recently solved asymptotic quantum Birkhoff conjecture, along with a systematic method of producing the examples using a geometric representation of Schur maps. Further properties of our channels including duality, quantum capacity, and entanglement preservation are discussed along with potential applications to additivity conjectures.

Crann, Jason; Neufang, Matthias

2013-02-01

14

An Estimation Method of Load Model Parameters for Harmonic Analysis  

NASA Astrophysics Data System (ADS)

In order to devise countermeasures for harmonic disturbances and harmonic suppression in power systems effectively, it is necessary to develop a harmonic analysis approach with high accuracy. The major harmonic analysis approach is to recreate harmonic distribution in a power system model by using a simulation method. However, in order to carry out high accuracy estimation of the harmonic distribution using the simulation method, after creating a load model which consists of several parameters associated with the measured harmonic impedance, the optimal load model parameters must be determined. So far, appropriate load model parameters have been determined by trial and error. Therefore, a systematic approach to determine the optimal load model parameters is needed to estimate the measured harmonic impedance with high accuracy. In this paper, a determination method for the optimal load model parameters to estimate the measured harmonic impedance is proposed. The proposed method is based on Particle Swarm Optimization (PSO), which is one of optimization methods by using concept of swarm intelligence. In order to check the validity of the proposed method, the load model parameters estimated by the proposed method are evaluated using test data and filed data of Hokuriku electric power company.

Hayashi, Yasuhiro; Matsuki, Junya; Kobayashi, Kenichi; Kanao, Norikazu

15

Operational modal analysis in the presence of harmonic excitation  

Microsoft Academic Search

Modal operational analysis methods are procedures to identify modal parameters of structures from the response to unknown random excitations existing on buildings and in machines during operation. In many practical cases, in addition to the random loads, harmonic excitations are also present due for instance to rotating components. If the frequency of the harmonic component of the input is close

P. Mohanty; D. J. Rixen

2004-01-01

16

Eccentric dipoles and spherical harmonic analysis  

NASA Astrophysics Data System (ADS)

Reference is made to a paper by Hurwitz (1960), bearing the same title, that gave formulas for the potential of eccentric dipoles both in closed form and in terms of spherical harmonic expressions for internal sources. Noting that more attention has recently been given to geomagnetic models that include external sources and believing that the spherical harmonic expression for external eccentric dipoles may be useful in such work, the work of Hurwitz is extended to external dipoles.

Alldredge, L. R.

17

Spherical harmonic analysis of earth’s conductive heat flow  

Microsoft Academic Search

A reappraisal of the international heat flow database has been carried out and the corrected data set was employed in spherical\\u000a harmonic analysis of the conductive component of global heat flow. Procedures used prior to harmonic analysis include analysis\\u000a of the heat flow data and determination of representative mean values for a set of discretized area elements of the surface

V. M. Hamza; R. R. Cardoso; C. F. Ponte Neto

2008-01-01

18

Harmonic Torque Calculation of Induction Motors Using Electromagnetic Field Analysis  

NASA Astrophysics Data System (ADS)

In this paper, we investigate effects of harmonic electromagnetic field to torque characteristics of induction motors from both side of experiment and electromagnetic field analysis. The characteristics of two kinds of the aluminum cage three-phase induction motors are measured and calculated. One is with the closed rotor slots. The other is semi-closed. In the experiment, the negative torque at synchronous speed is measured by driving the induction motor by the synchronous permanent magnet motor. The total torque at load condition is also measured by the torque detector. In the analysis, the harmonic magnetic fields, the harmonic losses and the harmonic torques at each time and space harmonic order are calculated using the nonlinear time-stepping finite element method to clarify the mechanism of the harmonic torque generation. The measured and the calculated results agree well. It is clarified that the negative torque caused by the slot harmonics at the rated load condition is not negligible and that the negative torque is mainly generated by the harmonic core losses.

Yamazaki, Katsumi; Haruishi, Yoshihisa; Ara, Takahiro

19

Aerodynamic Analysis of Cup Anemometers Performance: The Stationary Harmonic Response  

PubMed Central

The effect of cup anemometer shape parameters, such as the cups' shape, their size, and their center rotation radius, was experimentally analyzed. This analysis was based on both the calibration constants of the transfer function and the most important harmonic term of the rotor's movement, which due to the cup anemometer design is the third one. This harmonic analysis represents a new approach to study cup anemometer performances. The results clearly showed a good correlation between the average rotational speed of the anemometer's rotor and the mentioned third harmonic term of its movement.

Pindado, Santiago; Cubas, Javier; Sanz-Andres, Angel

2013-01-01

20

Spherical harmonic analysis of steady photospheric flows  

NASA Technical Reports Server (NTRS)

A technique is presented in which full disk Doppler velocity measurements are analyzed using spherical harmonic functions to determine the characteristics of the spectrum of spherical harmonic modes and the nature of steady photospheric flows. Synthetic data are constructed in order to test the technique. In spite of the mode mixing due to the lack of information about the motions on the backside of the sun, solar rotation and differential rotation can be accurately measured and monitored for secular changes, and meridional circulations with small amplitudes can be measured. Furthermore, limb shift measurements can be accurately obtained, and supergranules can be fully resolved and separated from giant cells by their spatial characteristics.

Hathaway, David H.

1987-01-01

21

Application of Modal Sensitivity for Power System Harmonic Resonance Analysis  

SciTech Connect

Abstract—Harmonic resonance is closely related to the singularity of a network admittance matrix. The smallest eigenvalue of the matrix defines the mode of harmonic resonance. This paper applies this eigenvalue theory and proposes a method to determine which network components have significant contributions to a harmonic resonance phenomenon. The basic idea is to calculate the sensitivities of a resonance mode to the parameters of network components. The sensitivity results are then ranked to quantify the impact of each component. In this paper, the eigen-sensitivity theory as applied to harmonic resonance mode analysis is presented. Case studies are used to verify the theory. A practical example is given to illustrate the application of the proposed method. In addition, this paper further conducts extensive comparative analysis on three types of network oriented modal analysis techniques. The results have clarified the similarities and differences among the techniques.

Huang, Zhenyu; Cui, Yu; Xu, Wilsun

2007-02-15

22

An electromagnetic time-harmonic analysis of shielded microstrip circuits  

Microsoft Academic Search

A Galerkin analysis of microstrip circuits of arbitrary planar geometry enclosed in a rectangular conducting box is described. The technique entails a time-harmonic electromagnetic analysis evaluating all fields and surface currents. This analysis is suitable for the accurate verification of microstrip designs prior to fabrication. A computer program implementing the analysis has been written in Pascal on a personal computer.

JAMES C. RAUTIO; Roger F. Harrington

1987-01-01

23

Physically Meaningful Harmonization of Tire\\/Pavement Friction Measurement Devices  

Microsoft Academic Search

Accurate characterization and evaluation of tire\\/pavement friction is critical in assuring runway and highway safety. Historically, Pavement Friction Measurement Devices (PFMDs) employing different measuring mechanisms have been used to evaluate tire\\/pavement friction. They yield significantly disparate friction coefficients under the same contact conditions. Currently, an empirically developed data harmonization method based on a reference device (Dynamic Friction Tester (DFT)) is

Madhura Priyanga Nishshanke Rajapakshe

2011-01-01

24

Harmonic measurements and analysis for power factor correction  

SciTech Connect

Maximizing electric power transfer directly effects the productivity of an electric arc furnace operation. Arc furnaces and rolling mill loads operate at power factors that result in penalty charges and lower bus voltages. In addition, the nonlinear characteristics of the furnace arcs and rolling mill drives generate significant harmonic currents that flow through the plant and utility power system. These harmonic currents cause system voltage distortions, power loss in the system, and can interact with power factor correction capacitor banks leading to equipment failures. This paper presents the analytical technique used to correct power factor in a modern steel manufacturing facility. The study included field measurements, harmonic analysis, and filter design work to reduce the amount of harmonic distortion in the plant. The modeling of arc furnaces and rolling mills for a harmonic analysis study is also discussed. The solution recommended in this paper to increase power factor and reduce harmonics can be applied to other steel manufacturing facilities to improve power quality and therefore plant productivity.

Witte, J.F.; Bishop, M.T. (Cooper Power Systems, Franksville, WI (United States)); Andrews, D. (North Star Steel Texas, Inc., Beaumont, TX (United States))

1993-07-01

25

Harmonic and Inter-harmonic Signal Analysis Based on Hilbert-Huang Transform  

Microsoft Academic Search

Because of the extensive application of the non- linear electrical equipment, aircraft power system contains a number of harmonic and inter-harmonic components. Aiming at the situation that Fourier transform and wavelet transform method could not effectively extract and analyze these harmonic and inter-harmonic signal, made use of Hilbert- Huang Transform (HHT) to extract and analyze harmonic and inter-harmonic components for

Wei Fu; Yan Zhu

2011-01-01

26

Equivalence of curvature and noncommutativity in a physical space: Harmonic oscillator on sphere  

NASA Astrophysics Data System (ADS)

We study the two-dimensional harmonic oscillator on a noncommutative plane. We show that by introducing appropriate Bopp shifts, one can obtain the Hamiltonian of a two-dimensional harmonic oscillator on a sphere according to the Higgs model. By calculating the commutation relations, we show that this noncommutativity is strictly dependent on the curvature of the background space. In other words, we introduce a kind of duality between noncommutativity and curvature by introducing noncommutativity parameters as functions of curvature. Also, it is shown that the physical realization of such model is a charged harmonic oscillator in the presence of electromagnetic field.

Ghorashi, S. A. A.; Mahdifar, A.; Roknizadeh, R.

2014-06-01

27

Spherical Harmonic Analysis for Spinors on H n ( C )  

Microsoft Academic Search

Recent results on the harmonic analysis of spinor fields on the complex hyperbolic space Hn(C) are reviewed. We discuss the action of the invariant differential operators on the Poisson transforms, the theory of spherical functions and the spherical transform. The inversion formula, the Paley–Wiener theorem, and the Plancherel theorem for the spherical transform are obtained by reduction to Jacobi analysis

Roberto Camporesi

2002-01-01

28

Sector spherical harmonic analysis of the solar magnetic field  

NASA Astrophysics Data System (ADS)

The theory of sector harmonic analysis has been developed as applied to the specific conditions of the solar magnetic field. A computer program has been developed. The possibilities of the program are illustrated in an analysis of a large-scale open solar field "singularity" observed on August 11, 2004, using MDI magnetometer data.

Kharshiladze, A. F.; Ivanov, K. G.

2013-01-01

29

A harmonic analysis of lunar gravity  

NASA Technical Reports Server (NTRS)

An improved model of lunar global gravity has been obtained by fitting a sixteenth-degree harmonic series to a combination of Doppler tracking data from Apollo missions 8, 12, 15, and 16, and Lunar Orbiters 1, 2, 3, 4, and 5, and laser ranging data to the lunar surface. To compensate for the irregular selenographic distribution of these data, the solution algorithm has also incorporated a semi-empirical a priori covariance function. Maps of the free-air gravity disturbance and its formal error are presented, as are free-air anomaly and Bouguer anomaly maps. The lunar gravitational variance spectrum has the form V(G; n) = O(n to the -4th power), as do the corresponding terrestrial and martian spectra. The variance spectra of the Bouguer corrections (topography converted to equivalent gravity) for these bodies have the same basic form as the observed gravity; and, in fact, the spectral ratios are nearly constant throughout the observed spectral range for each body. Despite this spectral compatibility, the correlation between gravity and topography is generally quite poor on a global scale.

Bills, B. G.; Ferrari, A. J.

1980-01-01

30

Relationship between the homotopy analysis method and harmonic balance method  

NASA Astrophysics Data System (ADS)

This paper presents a study of the relationship between the homotopy analysis method (HAM) and harmonic balance (HB) method. The HAM is employed to obtain periodic solutions of conservative oscillators and limit cycles of self-excited systems, respectively. Different from the usual procedures in the existing literature, the HAM is modified by retaining a given number of harmonics in higher-order approximations. It is proved that as long as the solution given by the modified HAM is convergent, it converges to one HB solution. The Duffing equation, the van der Pol equation and the flutter equation of a two-dimensional airfoil are taken as illustrations to validate the attained results.

Chen, Y. M.; Liu, J. K.; Meng, G.

2010-08-01

31

Topics in harmonic analysis with applications to radar and sonar  

Microsoft Academic Search

This minicourse is an introduction to basic concepts and tools in grouprepresentation theory, both commutative and noncommutative, that are fundamentalfor the analysis of radar and sonar imaging. Several symmetry groups of physicalinterest will be studied (circle, line, rotation, ax + b, Heisenberg, etc.) together withtheir associated transforms and representation theories (DFT, Fourier transform,expansions in spherical harmonics, wavelets, etc.). Through the

Willard Miller Jr.

1991-01-01

32

Harmonic component detection: Optimized Spectral Kurtosis for operational modal analysis  

NASA Astrophysics Data System (ADS)

This work is a contribution in the field of Operational Modal Analysis to identify the modal parameters of mechanical structures using only measured responses. The study deals with structural responses coupled with harmonic components amplitude and frequency modulated in a short range, a common combination for mechanical systems with engines and other rotating machines in operation. These harmonic components generate misleading data interpreted erroneously by the classical methods used in OMA. The present work attempts to differentiate maxima in spectra stemming from harmonic components and structural modes. The detection method proposed is based on the so-called Optimized Spectral Kurtosis and compared with others definitions of Spectral Kurtosis described in the literature. After a parametric study of the method, a critical study is performed on numerical simulations and then on an experimental structure in operation in order to assess the method's performance.

Dion, J.-L.; Tawfiq, I.; Chevallier, G.

2012-01-01

33

Harmonized Profiloplasty Using Balanced Angular Profile Analysis  

Microsoft Academic Search

To evaluate outcomes of aesthetic facial plastic surgery objectively the authors developed a photogrammetric profile analysis method, which they call “balanced angular profile analysis” (BAPA). To develop standards and ways to determine the conformation of various soft tissue segments analytically, 19 mean angular values acquired from the photographs of 71 famous female models (53 Eastern models and 18 Western models)

Heung Sik Park; Seung Chul Rhee; So Ra Kang; Ji Hyuck Lee

2004-01-01

34

Boston University Physics Applets: Simple Harmonic Motion and Uniform Circular Motion  

NSDL National Science Digital Library

This web page is an interactive Java simulation that illustrates the correlation between simple harmonic motion and uniform circular motion. The page describes the conditions in which this is true, and shows graphically that their motion in the x direction is identical. This item is part of a collection of similar simulation-based activities designed for introductory physics students.

Duffy, Andrew

2008-08-01

35

Investigations into the performance of various HBV physical structures for high efficiency harmonic generation  

Microsoft Academic Search

Heterostructure barrier varactors (HBV) with different physical structures have been investigated and characterised for their capacitance-voltage characteristic and device series resistance. This is a novel concept to increase the HBV capacitance modulation whilst minimize the device series resistance for the NLTL in achieving optimum harmonic generation. Various capacitance modulation characteristics can be engineered by shaping the HBV mesa with either

W. H. Chow; D. P. Steenson

2003-01-01

36

A note about Norbert Wiener and his contribution to Harmonic Analysis and Tauberian Theorems  

NASA Astrophysics Data System (ADS)

In this note we explain the main motivations Norbert Wiener had for the creation of his Generalized Harmonic Analysis [13] and his Tauberian Theorems [14]. Although these papers belong to the most pure mathematical tradition, they were deeply based on some Engineering and Physics Problems and Wiener was able to use them for such diverse areas as Optics, Brownian motion, Filter Theory, Prediction Theory and Cybernetics.

Almira, J. M.; Romero, A. E.

2009-05-01

37

HFAST - A harmonic analysis program for Stirling cycles  

NASA Technical Reports Server (NTRS)

HFAST is a general-purpose third-order harmonic analysis and design program for predicting the cyclic-steady state thermodynamic performance of Stirling cycles. It represents the state-of-the-art results of years of research efforts at Mechanical Technology Inc. (MTI) in the development of Stirling cycle machines. The code has been extensively used at MTI to support the development of both free-piston and kinematic Stirling cycle machines. Lately, HFAST has undergone many major improvements, both in the analysis method and in the user's interface. This paper presents a brief description of the current analysis method used in HFAST.

Huang, S. C.

1992-01-01

38

Venus gravity - A harmonic analysis and geophysical implications  

NASA Astrophysics Data System (ADS)

An improved theoretical model of Venusian global gravity has been obtained by fitting a tenth degree spherical harmonic series to 78 orbital arcs of Doppler tracking data from the Pioneer Venus Orbiter. Maps of the free-air anomaly and its formal error are presented. Isostatic anomaly and 'Geoid' maps are also presented, and their geophysical implications are discussed in details. Comparison with equivalent resolution topographic models reveals a strong correlation between long wavelength gravity and the topography of Venus. Analysis of the second degree harmonics showed two aspects of the orientation of the inertial axes of Venus: (1) a significant (about three degrees) departure of the axis of greatest inertia from the rotational axis; and (2) a near alignment of the axis of least inertia with the location of the subterrestrial point at the time of the next inferior conjunction with earth (December 16, 2101). A series of contour maps of the Venusian free-air anomalies is provided.

Mottinger, N. A.; Sjogren, W. L.; Bills, B. G.

1985-02-01

39

Harmonic and transient overvoltage analysis in arc furnace power systems  

SciTech Connect

The paper presents guidelines for analyzing harmonics and transient overvoltages generated by arc furnaces. Computer simulation techniques for creating accurate models for the analysis of arc furnace power systems are also discussed. Simulation guidelines are outlined in detail to assist the power systems engineer in performing a complete and accurate study of arc furnace power systems. These guidelines can be applied to melting and ladle furnace applications. General practices and designs encountered in arc furnace power systems are discussed. Possible solutions to common problems associated with arc furnace power systems are also discussed. Discussions of shunt capacitor bank arrangements, harmonic filter design, ferroresonance, virtual current chopping, the use of surge capacitors, and surge arresters are also included.

Mendis, S.R. (Systems Engineering Group, Cooper Power Systems, Franksville, WI (United States)); Gonzalez, D.A. (Components and Protective Equipment Plant, Cooper Power Systems, Pewaukee, WI (United States))

1992-04-01

40

BAYESIAN ANALYSIS OF MULTIPLE HARMONIC OSCILLATIONS IN THE SOLAR CORONA  

SciTech Connect

The detection of multiple mode harmonic kink oscillations in coronal loops enables us to obtain information on coronal density stratification and magnetic field expansion using seismology inversion techniques. The inference is based on the measurement of the period ratio between the fundamental mode and the first overtone and theoretical results for the period ratio under the hypotheses of coronal density stratification and magnetic field expansion of the wave guide. We present a Bayesian analysis of multiple mode harmonic oscillations for the inversion of the density scale height and magnetic flux tube expansion under each of the hypotheses. The two models are then compared using a Bayesian model comparison scheme to assess how plausible each one is given our current state of knowledge.

Arregui, I.; Asensio Ramos, A.; Diaz, A. J., E-mail: iarregui@iac.es [Instituto de Astrofisica de Canarias, Via Lactea s/n, E-38205 La Laguna, Tenerife (Spain)

2013-03-01

41

Analysis of second-harmonic generation of Lamb waves using a combined method in a two-layered solid waveguide  

NASA Astrophysics Data System (ADS)

Within the second-order perturbation treatment, the present work analyzed the complex second-harmonic generation of Lamb waves in a two-layered solid waveguide by combining the modal analysis method and the nonlinear reflection of acoustic waves at interfaces. The formal solution of the second-harmonic field is obtained on the basis of the modal analysis approach, from which a phase matching modification factor can be determined. The solution of the cumulative second-harmonic displacement field derived from the nonlinear reflection of acoustic waves at interfaces can be modified by multiplying the phase matching modification factor, and then be more general and applicable for the total second-harmonic field of Lamb wave propagation. Numerical computation results show that amplitude of the second-harmonic displacement increases clearly with propagation distance when the phase velocity of a double frequency Lamb wave (DFLW) component is exactly or approximately equivalent to that of the primary Lamb wave propagation, and reveal that the amplitudes of the second harmonics exhibit a decreasing tendency when the relative deviation of phase velocity between the primary Lamb wave and the DFLW component increases. Primary experimental measurements have been performed to verify the results of the numerical simulations in a FeCrNi alloy steel specimen. The research provides a further understanding for the physical process of the cumulative second-harmonic generation in a two-layered solid waveguide.

Xiang, Yanxun; Deng, Mingxi; Xuan, Fu-Zhen

2009-07-01

42

Physical librations due to the third and fourth degree harmonics of the lunar gravity potential  

Microsoft Academic Search

The existence of third and fourth harmonics of the lunar gravity potential gives rise to sizable lunar physical librations.\\u000a Using one recent set of potential estimates, the following effects are noted: the mean sub-Earth point is displaced from the\\u000a earthward principal moment of inertia axis by 168?; the inclination of the lunar equator to the ecliptic is decreased by 14?.5;

Donald H. Eckhardt; L. G. Hanscom

1973-01-01

43

A study on stress and vibration analysis of a steel and hybrid flexspline for harmonic drive  

Microsoft Academic Search

The conventional speed reducer uses the concept of rigid bodies, but the harmonic drive is operated by the elastic theory. As for this, harmonic drive shows different characteristics in operation principles and analysis compared to the conventional ones. Flexspline with components of harmonic drive can generate repeated vibration by the wave generator. Thus flexspline should have a good vibration characteristic.

Han Su Jeon; Se Hoon Oh

1999-01-01

44

Analysis of Cerenkov second harmonic generation in optical waveguides  

NASA Astrophysics Data System (ADS)

We pre8enI i c. spled mode analysis on Cerenku Second Hatrmonic Ceneration(SHG) 1. find osl nsmer ledly the harmonic power planar wave side. B. lh TE and TM modee are considered. The ci. fed of variatien 0/ use g*idc parameters on the cnivcru. n efficiency sa prcacnled. Nmerica1 reaI1a are preP 8enIeifor prolen e:changeililhi*m niohaie(FE:LiNIO6) vdvegvides. Improved cospling c. efficienta are used. Estension of the present s1dy te optical flere ie of lined. I

Balasubramanian, R.; Srinivas, Talabuttala; Selvarajan, Ananth

1992-12-01

45

Harmonic Analysis of Rail Transportation Systems with Probabilistic Techniques  

Microsoft Academic Search

Harmonics in rail transportation systems are an important design aspect. The overall load in these systems consists of a few large traction motors, often supplied by thyristor controlled choppers or PWM converters. These converters produce high levels of harmonic currents, which may extend into the kHz range. Recognizing harmonic problems in an early stage of development is important in order

J. van Casteren; F. Groeman

2006-01-01

46

Identifying aquifer type in fractured rock aquifers using harmonic analysis.  

PubMed

Determining aquifer type, unconfined, semi-confined, or confined, by drilling or performing pumping tests has inherent problems (i.e., cost and complex field issues) while sometimes yielding inconclusive results. An improved method to cost-effectively determine aquifer type would be beneficial for hydraulic mapping of complex aquifer systems like fractured rock aquifers. Earth tides are known to influence water levels in wells penetrating confined aquifers or unconfined thick, low-porosity aquifers. Water-level fluctuations in wells tapping confined and unconfined aquifers are also influenced by changes in barometric pressure. Harmonic analyses of water-level fluctuations of a thick (~1000 m) carbonate aquifer located in south-central Oklahoma (Arbuckle-Simpson aquifer) were utilized in nine wells to identify aquifer type by evaluating the influence of earth tides and barometric-pressure variations using signal identification. On the basis of the results, portions of the aquifer responded hydraulically as each type of aquifer even though there was no significant variation in lithostratigraphy. The aquifer type was depth dependent with confined conditions becoming more prevalent with depth. The results demonstrate that harmonic analysis is an accurate and low-cost method to determine aquifer type. PMID:22463080

Rahi, Khayyun A; Halihan, Todd

2013-01-01

47

Linux Physical Memory Analysis  

Microsoft Academic Search

We present a tool suite for analysis of physical memory usage within the Linux kernel environment. This tool suite can be used to collect and analyze how the physi- cal memory within a Linux environment is being used. Embedded subsystems are common in today's computer systems. These embedded subsystems range from the very simple to the very complex. In such

Paul Movall; Ward Nelson; Shaun Wetzstein

2005-01-01

48

Harmonic distortion analysis of a Mach-Zehnder intensity modulator  

NASA Astrophysics Data System (ADS)

With the aim to get harmonic distortion characteristics and frequency components of modulated output signals of a Mach-Zehnder (MZ) intensity modulator, this paper analyzes the optical intensity modulation transfer function by Tailor expandsion method according with the working principle of modulator. From the viewpoint of spectrum, the output signal is mainly comprised of the fundamental harmonic, the second intermodulation harmonic and the third intermodulation harmonic of the input signal and their magnitudes are connected with the bias voltage and Eigen-phase of MZ modulator. The second harmonic distortion and the fundamental harmonic of the modulated output signal are closely related with the drift of the best bias point. When the modulator works at the best DC bias voltage point, the modulated output signals have the minimum second harmonic distortion. If the best bias point drifts, the second harmonic distortion increases and the fundamental harmonic decreases, which changes in proportion to the sine or cosine of the drift voltage. A 1GHz sine signal with 1V amplitude imposed on the modulator, the simulation results by MATLAB presents that the waveform starts distorting along with the drifting of the best bias voltage, which the fundamental wave component starts decreasing and the second harmonic component starts increasing. While at last the fundamental wave component is zero, the frequency of output modulated signal doubles as much the frequency of input signal.

Zhang, Xiaoqing; Hu, Shuling; Jia, Yudong; Zhou, Zhehai; Liao, Lei

2013-10-01

49

Analysis of rotor vibratory loads using higher harmonic pitch control  

NASA Technical Reports Server (NTRS)

Experimental studies of isolated rotors in forward flight have indicated that higher harmonic pitch control can reduce rotor noise. These tests also show that such pitch inputs can generate substantial vibratory loads. The modification is summarized of the RotorCRAFT (Computation of Rotor Aerodynamics in Forward flighT) analysis of isolated rotors to study the vibratory loading generated by high frequency pitch inputs. The original RotorCRAFT code was developed for use in the computation of such loading, and uses a highly refined rotor wake model to facilitate this task. The extended version of RotorCRAFT incorporates a variety of new features including: arbitrary periodic root pitch control; computation of blade stresses and hub loads; improved modeling of near wake unsteady effects; and preliminary implementation of a coupled prediction of rotor airloads and noise. Correlation studies are carried out with existing blade stress and vibratory hub load data to assess the performance of the extended code.

Quackenbush, Todd R.; Bliss, Donald B.; Boschitsch, Alexander H.; Wachspress, Daniel A.

1992-01-01

50

Harmonic analysis of spacecraft power systems using a personal computer  

NASA Technical Reports Server (NTRS)

The effects that nonlinear devices such as ac/dc converters, HVDC transmission links, and motor drives have on spacecraft power systems are discussed. The nonsinusoidal currents, along with the corresponding voltages, are calculated by a harmonic power flow which decouples and solves for each harmonic component individually using an iterative Newton-Raphson algorithm. The sparsity of the harmonic equations and the overall Jacobian matrix is used to an advantage in terms of saving computer memory space and in terms of reducing computation time. The algorithm could also be modified to analyze each harmonic separately instead of all at the same time.

Williamson, Frank; Sheble, Gerald B.

1989-01-01

51

Time-domain analysis and experimental examination of cumulative second-harmonic generation by primary Lamb wave propagation  

NASA Astrophysics Data System (ADS)

Within the second-order perturbation approximation, the physical process of cumulative second-harmonic generation by the primary Lamb wave propagation has been investigated in the time domain. Based on the preconditions that the transfer of energy from the primary Lamb wave to the double frequency Lamb wave is not zero and that the phase velocity matching condition is satisfied, we focus on analyzing the influence of mismatching of the group velocities on the generation of the second harmonic by propagation of a primary Lamb wave tone burst with a finite duration. Our analysis indicates that the time-domain envelope of the second harmonic generated is dependent on the propagation distance when both the duration of the primary Lamb wave tone burst and the group velocity mismatch are given. Furthermore, it can be concluded that the integrated amplitude of the time-domain second harmonic, which quantifies the efficiency of the second-harmonic generation, grows with the propagation distance even when the group velocity matching condition is not satisfied. The experimental examination has been performed, and it verifies our theoretical analysis.

Deng, Mingxi; Xiang, Yanxun; Liu, Liangbing

2011-06-01

52

Harmonic analysis of multi-phase electric-power distribution systems  

Microsoft Academic Search

This study presents a computer program as a tool for the harmonic analysis of multi-phase electric power distribution systems. In the program, the source of harmonics can be any number of multi-phase harmonic currents and\\/or voltages, or up to 10 three-phase converts. Frequency-dependent models of ac network elements are assembled into a sparse admittance matrix. Then, sparsity techniques are employed

Hosseini

1988-01-01

53

Harmonic analysis of slip energy recovery induction motor drives  

Microsoft Academic Search

The impact of electric drives on the power system in terms of harmonic generation is becoming increasingly important. Slip energy recovery induction motor drives (SERIMDs) have the rectifier and inverter connected to the rotor instead of the stator (the case in most conventional drives). The harmonic content of the SERIMD is thus quite different and arguably, less onerous than conventional

L. Refoufi; P. Pillay

1994-01-01

54

Harmonic analysis utilizing a Phonodeik and an Henrici analyzer  

NASA Astrophysics Data System (ADS)

Dayton C. Miller of the Case School of Applied Science assembled a series of instruments for accurate analysis of sound [D. C. Miller, J. Franklin Inst. 182, 285-322 (1916)]. He created the Phonodeik to display and record sound waveforms of musical instruments, voices, fog horns, and so on. Waveforms were analyzed with the Henrici harmonic analyzer, built in Switzerland by G. Coradi. In this device, the motion of a stylus along the curve to be analyzed causes a series of spheres to rotate; two moveable rollers in contact with the nth sphere record the contributions of the sine(nx) and cosine(nx) components of the wave. Corrections for the measured spectra are calculated from analysis of the response of the Phonodeik. Finally, the original waveform could be reconstructed from the corrected spectral amplitudes and phases by a waveform synthesizer, also built at Case. Videos will be presented that show the motion of the gears, spheres, and dials of a working Henrici analyzer, housed at the Department of Speech Pathology and Audiology at the University of Iowa. Operation of the Henrici analyzer and the waveform synthesizer will be explained.

Fickinger, William J.; Hanson, Roger J.; Hoekje, Peter L.

2001-05-01

55

Harmonic analysis of multi-phase electric-power distribution systems  

SciTech Connect

This study presents a computer program as a tool for the harmonic analysis of multi-phase electric power distribution systems. In the program, the source of harmonics can be any number of multi-phase harmonic currents and/or voltages, or up to 10 three-phase converts. Frequency-dependent models of ac network elements are assembled into a sparse admittance matrix. Then, sparsity techniques are employed to determine the current flow in all elements and voltages at all busses throughout the system at any harmonic frequency up to 3 KHz. Voltage distortion factors that represent the overall effects of the harmonics of the system voltages are also calculated. The digital program was then applied to a multi-phase distribution system in order to observe the response of the system to the various changes that were made in the system. It was found that the converter size and location, the capacitor bank sizes and locations, and the representation of the system loads are factors in determining in harmonic current flows and the level of voltage-distortion factors. Also, the response of the system to single-phase harmonic sources was investigated, and it was discovered that the effects of single-phase harmonic sources can be serious enough that they should not be ignored in the harmonic analysis of multi-phase systems.

Hosseini, S.H.

1988-01-01

56

Harmonizing Physics & Cosmology With Everything Else in the Universe(s)  

NASA Astrophysics Data System (ADS)

This paper postulates a theory of everything including our known finite physical universe within and as sub-set of an infinite virtual invisible universe occupying some of the same space and time. It attempts to harmonize astrophysics with everything else including life. It compares and contrasts properties, similarities, differences and relationships between the two universe(s). A particular attention is paid to the interface between the two and the challenges of building and/or traversing bridges between them. A number of inflection points between the two are identified. The paper also delineates their relationship to big bang, theory of evolution, gravity, dark matter, black holes, time travel, speed of light, theory of relativity and string theory just to name a few. Several new terms are introduced and defined to discuss proper relationship, transition and interface between the body, soul and spirit as well as their relationship to brain and mind. Physical bodies & beings are compared with virtual, meta and ultra bodies and beings and how the ``Virtual Inside'' relates to people, pets, plants and particles and their micro constituents as well as macro sets. The past, present, and potential of the concurrent universe(s) is compared and contrasted along with many myths and misconceptions of the meta physics as well as modern physics.

Asija, Pal

2006-03-01

57

Analysis of the harmonic gyrotron traveling wave amplifier  

NASA Technical Reports Server (NTRS)

A single nonlinear differential equation is derived for describing the spatial evolution of the wave field in a gyrotron amplifier on the cylindrical guide geometry. The equation is then used to determine the efficiencies and the optimized interaction lengths for gyrotron operated with TE sub N1 modes at the N-th cyclotron harmonic. The equation offers a significant advantage in simplifying numerical work in comparison with the brute force particle simulation approach. The efficiencies of the harmonic operations by using a hollow beam decrease quickly with increasing harmonic number, but are enhanced by using an axis-encircling beam instead.

Kuo, S. P.; Kuo, S. C.; Cheo, B. R.; Lee, M. C.

1986-01-01

58

Power system harmonic analysis based on improved hilbert-huang transform  

Microsoft Academic Search

To analyze harmonic accurately is significant to the stability of power system. HHT (Hilbert-Huang Transform) is adopted to analyze harmonic in order to overcome the shortcoming of FFT method and wavelet analysis method. The power quality signals are decomposed by empirical mode decomposition (EMD) method, and then a series of intrinsic mode function (IMF) are obtained. Owing to different IMFs

Shi Zhang; Qun Wang; Ruirui Liu

2009-01-01

59

Bioimpedance harmonic analysis as a tool to simultaneously assess circulation and nervous control  

Microsoft Academic Search

Multicycle harmonic (Fourier) analysis of bioimpedance was employed to simultaneously assess circulation and neural activity in visceral (rat urinary bladder) and somatic (human finger) organs. The informative value of the first cardiac harmonic of the bladder impedance as an index of bladder circulation is demonstrated. The individual reactions of normal and obstructive bladders in response to infusion cystometry were recorded.

I. S. Mudraya; S. V. Revenko; A. V. Nesterov; I. Yu Gavrilov; V. I. Kirpatovsky

2011-01-01

60

Crop identification using harmonic analysis of time-series AVHRR NDVI data  

Microsoft Academic Search

Harmonic analysis of a time series of National Oceanic and Atmospheric Administration (NOAA) advanced very high resolution radiometer normalized difference vegetation index (NDVI) data was used to develop an innovative technique for crop type identification based on temporal changes in NDVI values. Different crops (corn, soybeans, alfalfa) exhibit distinctive seasonal patterns of NDVI variation that have strong periodic characteristics. Harmonic

Mark E Jakubauskas; David R Legates; Jude H Kastens

2002-01-01

61

Harmonic-Resonance Analysis in a Maglev Feeding System  

NASA Astrophysics Data System (ADS)

A feeding circuit for a superconducting magnetic levitation train system, or the so-called “maglev” consists of feeder cables and armature coils which show characteristics of a distributed-parameter line. Electric power is supplied to the cables and coils by PWM inverters whose output voltage contains a large amount of harmonics. As a result, a harmonic resonance may occur in the feeding circuit. Besides the above characteristics, the connecting point of sections (groups of armature coils) or the feeder cables length changes according to the movement of a maglev train, thus causing changes in the harmonic-resonance characteristics of the feeding circuit. This paper describes analytical results of the harmonic resonance in the feeding circuit for the maglev, with the focus on changes in the connecting point of sections and the feeder cables length.

Shigeeda, Hidenori; Okui, Akinobu; Akagi, Hirofumi

62

Determining the Third-Harmonic Susceptibility by Fourier Analysis  

Microsoft Academic Search

A novel analyzing procedure was introduced to extract the third-harmonic susceptibility from the measured third-harmonic-generation fringe obtained by translating a wedged liquid cell along the direction perpendicular to the propagating direction of the incident fundamental beam. By Fourier transform, we can easily separate the Fourier component purely contributed by the liquid\\/window interface from those involving the air contribution. Comparing this

Pao-Keng Yang

2008-01-01

63

Analysis of cyclotron harmonic emissions at the outer planets  

NASA Technical Reports Server (NTRS)

The flyby missions of Voyagers 1 and 2 at Jupiter, Saturn and Uranus revealed intense waves above the electron gyrofrequency. Observation of waves at the upper hybrid frequency is often accompanied by power at adjacent electron Bernstein harmonics, and the relative power in these modes depends both on the density and temperature ratios of the cold background electron population and the hot magnetospheric electrons which drive the instability. A model of electron distributions which is consistent with observations is used for analysis of the excited waves, their dependence upon plasma parameters, and the time scales of the saturation processes. It is shown that in the presence of two-temperature electron distributions the linear excitation is due to a fluidlike coupling of two eigenmodes for perpendicular propagation and to kinetic destalization of oblique modes. The dependence of linear growth rates on propagation angle is presented, along with results from particle simulations. A quasi-linear diffusion time for relaxing the hot electron loss cone is calculated and compared with simulation results. This time scale is faster than for local saturation by heating the cold population, and also the convective amplification time scale, suggesting that the waves saturate at quasi-linear levels, while being convectively localized to the equatorial regions of the outer planetary magnetospheres.

Roth, I.; Hudson, M. K.

1992-01-01

64

Spherical harmonic analysis of steady photospheric flows. II  

NASA Technical Reports Server (NTRS)

The use of the spherical harmonic functions to analyze the nearly steady flows in the solar photosphere is extended to situations in which B(0) the latitude at disk center, is nonzero and spurious velocities are present. The procedures for extracting the rotation profile and meridional circulation are altered to account for the seasonal tilt of the sun's rotation axis toward and away from the observer. A more robust and accurate method for separating the limb shift and meridional circulation signals is described. The analysis procedures include the ability to mask out areas containing spurious velocities (velocity-like signals that do not represent true flow velocities in the photosphere). The procedures are shown to work well in extracting the various flow components from realistic artificial data with a broad, continuous spectrum for the supergranulation. The presence of this supergranulation signal introduces errors of a few m/s in the measurements of the rotation profile, meridional circulation, and limb shift from a single Doppler image.

Hathaway, David H.

1992-01-01

65

Error analysis for dielectric loss factor measurement based on harmonic analysis  

Microsoft Academic Search

Dielectric loss measurement is an important index in assessing the insulation performance of power equipment. With the development of condition-based maintenance, the on-line diagnostic technologies for dielectric loss measurement are regarded more and more. Many methods have been developed in this field in which harmonic analysis is prevalent due to its perfect performance of resisting disturbance and stability relative to

Yang Minzhong; Liu Shaoyu; Wang Zhuo; Yan Zhang

2001-01-01

66

Harmonic Analysis of the Cone Flicker ERG of Rabbit  

PubMed Central

Harmonic analysis was used to characterize the rabbit flicker ERG elicited by sinusoidally modulated full-field stimuli under light-adapted conditions. The frequency-response function for fundamental amplitude, derived from Fourier analysis of the ERG waveforms, exhibited two limbs, with an amplitude minimum at approximately 30 Hz, and a high-frequency region peaking at around 45 Hz and extending to more than 100 Hz at higher adapting levels. At low frequencies (< 20 Hz), the fundamental response amplitude was independent of mean luminance (Weber law behavior), whereas the response amplitude at high stimulus frequencies varied nonlinearly with mean luminance. At low frequencies, intravitreal administration of L-AP4, which blocks ON-pathway activity, reduced the fundamental response amplitude and produced a phase shift. On the other hand, PDA, which reduces OFF-pathway activity, had a minimal effect on both the response amplitude and phase at low frequencies. At high frequencies, L-AP4 increased the fundamental response amplitude at low mean luminances, whereas PDA had only a small effect on amplitude and phase. Both pharmacologic agents removed the minimum in the amplitude-frequency function as well as the abrupt change in phase at stimulus frequencies near 30 Hz. The results suggest that there is a nonlinear interaction between ON- and OFF-pathway activity over the entire stimulus frequency range examined in this study. These findings provide a basis for formulating protocols to evaluate the effect of pharmacologic agents and/or disease on the cone flicker ERG of rabbit.

Qian, Haohua; Alexander, Kenneth R.; Ripps, Harris

2010-01-01

67

Modeling of electric railway vehicle for harmonic analysis of traction power-supply system using spline interpolation in frequency domain  

Microsoft Academic Search

It is essential to model nonlinear traction power converter loads for the harmonic analysis of traction systems. A behavioral model in the frequency domain to represent electric railway vehicles based on testing and measurements is proposed for harmonic analysis. The harmonic current characteristics are represented by a set of polynomials generated from cubic smoothing spline interpolation. The purpose of this

K. H. Yuen; M. H. Pong; W. C. Lo; Z. M. Ye

1999-01-01

68

Blind Analysis in Particle Physics  

NASA Astrophysics Data System (ADS)

A review of the blind analysis technique, as used in particle physics measurements, is presented. The history of blind analyses in physics is briefly discussed. Next the dangers of "experimenter's bias" and the advantages of a blind analysis are described. Three distinct kinds of blind analysis in particle physics are presented in detail. Finally, the BABAR collaboration's experience with the blind analysis technique is discussed.

Roodman, Aaron

69

Physical pendulum experiments to enhance the understanding of moments of inertia and simple harmonic motion  

NASA Astrophysics Data System (ADS)

This paper describes a set of experiments aimed at overcoming some of the difficulties experienced by students learning about the topics of moments of inertia and simple harmonic motion, both of which are often perceived to be complex topics amongst students during their first-year university courses. By combining both subjects in a discussion about physical pendula, in which the oscillation time periods for the periodic motion of several objects (a tennis ball, a thin beam, a hoop and a solid disc) are measured and compared, students are able to understand both topics at a higher level and also experience the synergistic effect of combining two or more physics themes in order to accelerate their learning whilst simultaneously raising their motivation. Special attention is given to the ‘ball and stick’ pendulum in which a block of material (treated as a point mass) can be moved along a shaft to create a composite pendulum whose time period exhibits a minimum value at a certain separation between the block and the rotation axis.

Richardson, Tim H.; Brittle, Stuart A.

2012-09-01

70

The Analysis And Design Of Harmonic Gear Drives  

Microsoft Academic Search

Harmonic gear drive, a compact mechanical device producing high mechanical advantage and speed reduction, has been used to accurately position the arms and wrists of robots. This device, operating on the principle of nonrigid body mechanicsr has been found to have positioning errors. Such errors, inherent in the drive, adversely affect the performance. In this paper, a kinematic model is

Lih-Min Hsia

1988-01-01

71

Practical Analysis of Single Electron Pump with Harmonic Drive  

Microsoft Academic Search

We study a two-gate single electron pump device with harmonic AC gate voltages. We have performed numerical and analytical calculations of quantum correction to a DC current due to the cotunneling phenomena. This correction determines the accuracy of the device in a wide range of parameters (temperature, frequency and amplitude of the gate voltage modulation). We found the crossover from

Akio Iwasa; Akio Fukushima; Arkadi A. Odintsov

1995-01-01

72

Harmonic Analysis of Zonal Density Structures in Martian Upper Atmosphere  

NASA Astrophysics Data System (ADS)

Mars Global Surveyor Accelerometer measurements of density in the martian upper atmosphere during aerobraking are now available via the PDS [Keating et al, 2001]. We are continuing our investigations of variations in density with longitude at fixed local solar time, latitude, and season, concentrating on Phase 2 of aerobraking. We find that, contrary to previous suspicions, the zonal structure is not dominated solely by wave-2 harmonics. The dominant harmonics are as follows: wave-3 in the northern extratropics, wave-2 and wave-3 in the tropics, and no clearly dominant harmonic in the southern extratropics. The relative amplitudes of the various harmonics vary with latitude. However, their phases remain very stable, despite large changes in the phasing of the corresponding harmonic of zonal topography. Relative to the mean density, the amplitudes of the various harmonics decrease as altitude increases. This is opposite to the behaviour predicted by a simple, dissipation-less model of the martian upper atmosphere, in which deviations from the background state of the atmosphere are proportional to the inverse of the square root of pressure, and indicates the presence of damping in the upper atmosphere. When the martian day was an integer multiple of the spacecraft orbital period, the accelerometer measured densities at the same latitude, local solar time, season, and longitude each martian day. This period of resonance lasted for several days as the spacecraft orbital period decreased through the critical value due to drag. This permits us to examine the true variability of the martian upper atmosphere without the complications of the zonal variability. An accurate estimate of this essentially unpredictable variability is crucial for effective and efficient aerobraking of future spacecraft missions. At an altitude of 130 km, variabilities of 15 percent were typical, though values of 30 percent were observed. This variability also decreased as altitude increased, an independent indication of damping and dissipation in the martian upper atmosphere. G.M. Keating, R.H. Tolson, J.L. Hanna, R.F. Beebe, J.R. Murphy and L.F. Huber, MGS-M-ACCEL-5-ALTITUDE-V1.0, NASA Planetary Data System, 2001.

Withers, P.; Bougher, S. W.; Keating, G. M.

2001-05-01

73

Harmonic analysis of the DC capacitor voltage in modular multilevel converter based STATCOM  

Microsoft Academic Search

The floating dc capacitor voltage of modular multilevel converter based STATCOM (M-STATCOM) contains a large amount of low-order harmonic components, which produce current ripple in leg currents, and then greatly affect the output performance and safe operation of M-STATCOM. However, fewer papers have made explicit harmonic analysis on the floating capacitor voltage of M-STATCOM. Detailed floating capacitor voltage computation has

Xiaofeng Yang; Jianghong Li; Xiaopeng Wang; Wenbao Fan; Trillion Q. Zheng

2011-01-01

74

Analysis of higher harmonic contamination with a modified approach using a grating analyser.  

PubMed

Soft x-ray spectra of the toroidal grating monochromator (TGM) at the reflectivity beamline of Indus-1 synchrotron source are analyzed for higher harmonic contribution. A diffraction grating of central line spacing 1200 l/mm is used to disperse the monochromatic beam received from TGM to quantify the harmonic contents in the 50-360 Å wavelength range. In order to calculate the harmonic contamination, conventionally the intensity of higher order peak is divided by first order peak intensity of the desired wavelength. This approach is found to give wrong estimate as first order peak itself is overlapped by higher order peaks. In the present study, a modified approach has been proposed to calculate harmonic contamination where the intensity contributions of overlapping orders have been removed from the first order diffraction peak of the desired wavelength. It is found that the order contamination in the TGM spectra is less than 15% in the wavelength range of 90-180 Å. The total harmonic contribution increases from 6%-60% in the wavelength range of 150-260 Å. The critical wavelength of Indus-1 is 61 Å hence the harmonic contamination below 90 Å is significantly low. The results obtained with modified approach match well with those obtained by quantitative analysis of multilayer reflectivity data. The obtained higher harmonics data are used to fit the transmission of aluminum edge filter in the 120-360 Å wavelength range. PMID:24784593

Gupta, Rajkumar; Modi, Mohammed H; Kumar, M; Chakera, J A; Lodha, G S

2014-04-01

75

Analysis of higher harmonic contamination with a modified approach using a grating analyser  

NASA Astrophysics Data System (ADS)

Soft x-ray spectra of the toroidal grating monochromator (TGM) at the reflectivity beamline of Indus-1 synchrotron source are analyzed for higher harmonic contribution. A diffraction grating of central line spacing 1200 l/mm is used to disperse the monochromatic beam received from TGM to quantify the harmonic contents in the 50-360 Å wavelength range. In order to calculate the harmonic contamination, conventionally the intensity of higher order peak is divided by first order peak intensity of the desired wavelength. This approach is found to give wrong estimate as first order peak itself is overlapped by higher order peaks. In the present study, a modified approach has been proposed to calculate harmonic contamination where the intensity contributions of overlapping orders have been removed from the first order diffraction peak of the desired wavelength. It is found that the order contamination in the TGM spectra is less than 15% in the wavelength range of 90-180 Å. The total harmonic contribution increases from 6%-60% in the wavelength range of 150-260 Å. The critical wavelength of Indus-1 is 61 Å hence the harmonic contamination below 90 Å is significantly low. The results obtained with modified approach match well with those obtained by quantitative analysis of multilayer reflectivity data. The obtained higher harmonics data are used to fit the transmission of aluminum edge filter in the 120-360 Å wavelength range.

Gupta, Rajkumar; Modi, Mohammed H.; Kumar, M.; Chakera, J. A.; Lodha, G. S.

2014-04-01

76

Spherical harmonic analysis of cortical complexity in autism and dyslexia  

PubMed Central

Alterations in gyral form and complexity have been consistently noted in both autism and dyslexia. In this present study, we apply spherical harmonics, an established technique which we have exapted to estimate surface complexity of the brain, in order to identify abnormalities in gyrification between autistics, dyslexics, and controls. On the order of absolute surface complexity, autism exhibits the most extreme phenotype, controls occupy the intermediate ranges, and dyslexics exhibit lesser surface complexity. Here, we synthesize our findings which demarcate these three groups and review how factors controlling neocortical proliferation and neuronal migration may lead to these distinctive phenotypes.

Williams, Emily L.; El-Baz, Ayman; Nitzken, Matthew; Switala, Andrew E.; Casanova, Manuel F.

2012-01-01

77

Spherical navigator registration using harmonic analysis for prospective motion correction.  

PubMed

Spherical navigators are an attractive approach to motion compensation in Magnetic Resonance Imaging. Because they can be acquired quickly, spherical navigators have the potential to measure and correct for rigid motion during image acquisition (prospectively as opposed to retrospectively). A limiting factor to prospective use of navigators is the time required to estimate the motion parameters. This estimation problem can be separated into a rotational and translational component. Recovery of the rotational motion can be cast as a registration of functions defined on a sphere. Previous methods for solving this registration problem are based on optimization strategies that are iterative and require k-space interpolation. Such approaches have undesirable convergence behavior for prospective use since the estimation complexity depends on both the number of samples and the amount of rotation. We propose and demonstrate an efficient algorithm for recovery of rotational motion using spherical navigators. We decompose the navigator magnitude using the spherical harmonic transform. In this framework, rigid rotations can be recovered from an over-constrained system of equations, leading to a computationally efficient algorithm for prospective motion compensation. The resulting algorithm is compared to existing approaches in simulated and actual navigator data. These results show that the spherical harmonic based estimation algorithm is significantly faster than existing methods and so is suited for prospective motion correction. PMID:17354740

Wyatt, C L; Ari, N; Kraft, R A

2005-01-01

78

Comparison Among Three Harmonic Analysis Techniques on the Sphere and the Ellipsoid  

NASA Astrophysics Data System (ADS)

The paper presents a comparison among three different techniques for harmonic analysis on the sphere and the ellipsoid. The EGM2008 global geopotential model has been used up to degree and order 360 in order to create gravity anomaly fields on both the sphere and the ellipsoid as the function fields of the current investigation. Harmonic analysis has then been carried out to compute the dimensionless potential coeficients using the created function fields. Three different harmonic analysis techniques have been applied: the least-squares technique, the Fast Fourier Transform (FFT) technique and the Gauss-Legendre numerical integration technique. The computed coeficients in spherical harmonics have then been compared with EGM2008 (in the frequency domain) and the computed fields on the sphere and the ellipsoid have been compared with fields created by EGM2008 up to degree and order 360 (in the space domain) in order to estimate the accuracy of the three different harmonic analysis techniques used within the current investigation. The results proved that the least-squares technique gives the best accuracy both in frequency and space domain. The FFT technique provides quite good results in a very short cpu time. The Gauss-Legendre technique gives the worst results among the presented techniques, but still the residuals in the space domain are negligibly small.

Abd-Elmotaal, Hussein; Abd-Elbaky, Mostafa; Seitz, Kurt; Heck, Bernhard

2014-04-01

79

Weighted Hardy-Littlewood Theorems for Conjugate A-Harmonic Tensors  

NASA Astrophysics Data System (ADS)

In this paper, we establish some versions of A(? 1(x), ? 2(x), ?, ?)-weighted Hardy-Littlewood inequalities for conjugate A-harmonic tensors, the theory of harmonic analysis and A-harmonic differential forms largely pertain to applications in mathematical physics, quantum field theory, elementary particle physics, etc.

Wen, Haiyu

2014-05-01

80

Theoretical analysis of waveguide second-harmonic generation phase matched with uniform and chirped gratings  

Microsoft Academic Search

Theoretical analysis of second-harmonic generation (SHG) phase matched with gratings in a channel waveguide is presented from the viewpoint of device design. The analysis includes cases where efficiency is high and residual phase mismatch is involved. Nonlinear couples mode equations, with general expressions for effective SHG coefficients and coupling coefficients, are derived, solved, and discussed for uniform and chirped gratings.

T. Suhara; H. Nishihara

1990-01-01

81

Data Analysis in Physics Examination  

ERIC Educational Resources Information Center

This paper presents a critical analysis of data analysis requirements in physics tertiary entrance examinations. The setting is Western Australia. Common aspects of the questions asked over 14 years and changes in the questions since a major syllabus reform are identified. Similar changes in other jurisdictions are referenced. The data analysis

Forster, Patricia A.

2005-01-01

82

Quantitative analysis of biological tissues using Fourier transform-second-harmonic generation imaging  

NASA Astrophysics Data System (ADS)

We demonstrate the use of Fourier transform-second-harmonic generation (FT-SHG) imaging of collagen fibers as a means of performing quantitative analysis of obtained images of selected spatial regions in porcine trachea, ear, and cornea. Two quantitative markers, preferred orientation and maximum spatial frequency are proposed for differentiating structural information between various spatial regions of interest in the specimens. The ear shows consistent maximum spatial frequency and orientation as also observed in its real-space image. However, there are observable changes in the orientation and minimum feature size of fibers in the trachea indicating a more random organization. Finally, the analysis is applied to a 3D image stack of the cornea. It is shown that the standard deviation of the orientation is sensitive to the randomness in fiber orientation. Regions with variations in the maximum spatial frequency, but with relatively constant orientation, suggest that maximum spatial frequency is useful as an independent quantitative marker. We emphasize that FT-SHG is a simple, yet powerful, tool for extracting information from images that is not obvious in real space. This technique can be used as a quantitative biomarker to assess the structure of collagen fibers that may change due to damage from disease or physical injury.

Ambekar Ramachandra Rao, Raghu; Mehta, Monal R.; Toussaint, Kimani C., Jr.

2010-02-01

83

High-order harmonic generation in graphite plasma plumes using ultrashort laser pulses: a systematic analysis of harmonic radiation and plasma conditions  

NASA Astrophysics Data System (ADS)

High-order harmonic generation in graphite-ablated plasmas was systematically studied using ultrashort (3.5 and 30 fs) laser pulses. We observed the efficient frequency conversion of 3.5 fs Ti:sapphire laser pulses in the range of 15-26 eV. Stabilization of the harmonic yield at a 1 kHz pulse repetition rate was accomplished using a rotating graphite target. We also show the results of harmonic generation in carbon plasma using 1300 nm, 40 ps pulses, which allowed the extension of the harmonic cutoff while maintaining a comparable conversion efficiency to the case of 780 nm driving radiation. The time-of-flight mass spectrometric analysis of the plasma components and the scanning electron microscopy of plasma debris under optimal conditions for harmonic generation suggest the presence of small carbon clusters (C10-C30) in the plasma plume at the moment of femtosecond pulse propagation, which further aggregate on nearby substrates. We present the results of plasma spectroscopy obtained under unoptimized plasma conditions that elucidate the reduction in harmonic signal. We also present calculations of plasma concentration under different excitation conditions of the ablated graphite target.

Ganeev, R. A.; Hutchison, C.; Witting, T.; Frank, F.; Okell, W. A.; Zaïr, A.; Weber, S.; Redkin, P. V.; Lei, D. Y.; Roschuk, T.; Maier, S. A.; López-Quintás, I.; Martín, M.; Castillejo, M.; Tisch, J. W. G.; Marangos, J. P.

2012-08-01

84

High field physics and extreme nonlinear optics. Brilliance measurement of high order harmonic generation  

NASA Astrophysics Data System (ADS)

Despite the fact that high order harmonic generation (HHG) aims at serving as a table-top light source for imaging applications with extremely high spatial resolution, a general lack of accurate conversion efficiency measurements exists in the field. Here, we present such a measurement for a HHG setup with a semi-infinite gas cell. By combining measurements with a calibrated photodiode sensitive in the extreme ultra-violet (XUV) and spatially resolved spectral measurements of HHG spectra, we are able to determine conversion efficiencies of the HHG process as well as brilliance values for individual harmonics. The method is explained in detail and applicable to any target geometry.

Teichmann, S. M.; Bisht, N.; Hidalgo, M.; Honarfar, A.; Mingolla, M. G.; Turconi, M.; Clerici, M.; di Trapani, P.; Biegert, J.

2011-11-01

85

Physical Pendulum Experiments to Enhance the Understanding of Moments of Inertia and Simple Harmonic Motion  

ERIC Educational Resources Information Center

This paper describes a set of experiments aimed at overcoming some of the difficulties experienced by students learning about the topics of moments of inertia and simple harmonic motion, both of which are often perceived to be complex topics amongst students during their first-year university courses. By combining both subjects in a discussion…

Richardson, Tim H.; Brittle, Stuart A.

2012-01-01

86

The development and analysis of geopotential coefficient models to spherical harmonic degree 360  

NASA Technical Reports Server (NTRS)

Two new geopotential coefficient models to spherical harmonic degree 360 are developed using recent advances made in theoretical modeling methods, satellite gravitational models, and expanded and improved terrestrial data. The new models are based on the combination of a satellite potential coefficient model (GEM-T2) to degree 50 with 30-arc mean gravity anomalies, yielding an adjusted set of coefficients and gravity anomalies, which were then harmonically analyzed to yield a set of potential coefficients to degree 360. The models were verified in several ways including satellite orbit residual analysis, demonstrating a substantial improvement over previous high-degree expansions.

Rapp, Richard H.; Pavlis, Nikolaos K.

1990-01-01

87

Visual relevance evaluation using Rate Distortion analysis in the Circular Harmonic Functions Domain  

Microsoft Academic Search

In this paper we develop a strategy for visual relevancy evaluation using Rate Distortion analysis in the Circular Harmonic Functions (CHF) Domain. In the CHF domain, the different visual characteristics of the transformed frames - edges, lines, forks, crosses, etc - are emphasized. Resorting to this domain we analyze a new approach to evaluate the distortion due to an event

Stefania Colonnese; Stefano Rinauro; Lorenzo Rossi; Gaetano Scarano

2009-01-01

88

Calculation of the Actual Tidal Fluctuations in Harmonic Analysis (Vychislenie Istinnykh Prilivnykh Kolebanii Pri Garmonicheskom Analize).  

National Technical Information Service (NTIS)

The paper discusses more accurate calculation methods of the actual tidal fluctuations of sea level and ebb-tide currents that are necessary for harmonic analysis. A new method for the filtration of tides, which differs from the method of separating wave ...

V. M. Altshuler

1968-01-01

89

Harmonic Analysis of Noninvasively Recorded Arterial Pressure Waveforms in Healthy Bonnet Macaques (Macaca radiata)  

PubMed Central

To characterize primate arterial waveforms, we prospectively studied 38 bonnet macaques (Macaca radiata; 25 female, 13 ± 4 y). Brachial artery waveforms were recorded from these animals by applanation tonometry and were decomposed into harmonics by using Fourier analysis. The ratio of individual to total harmonic amplitude (H:T) was derived from frequency spectra. Left ventricular (LV) mass, ejection fraction, fractional shortening, septal wall thickness, posterior wall thickness, LV end-diastolic diameter, and LV end-systolic diameter were obtained by echocardiography in all 38 monkeys. Blood pressure was obtained by sphygmomanometry. The fundamental frequency was 2.76 cycles/s. Harmonics ranged from 5 to 14. Indexed LV mass was inversely correlated with third H:T and second H:T but not with systolic or diastolic blood pressure. In addition, the third H:T was inversely correlated with septal wall thickness, posterior wall thickness, and LV end-diastolic diameter, whereas second H:T was inversely correlated with LV end-diastolic diameter. Heart rate was inversely correlated with eighth H:T. On multivariate analysis adjusting for age, gender, weight, and length, only third H:T was an independent predictor of LV mass. Harmonic analysis of arterial waveforms may provide information pertaining to LV mass. Lower H:T ratios (second and third) are related to LV mass, whereas higher H:T (eighth) is related to heart rate.

Olafiranye, Oladipupo; Salciccioli, Louis; Kamran, Haroon; Stewart, Mark; Carter, John; Lazar, Jason M

2011-01-01

90

Physics Teaching Technology Resource: Learning Cycles on Harmonic Motion and Waves  

NSDL National Science Digital Library

This learning cycle features nine videotaped experiments, organized sequentially for introducing fundamentals of harmonic motion and waves. Each video includes learning goal, prior knowledge required, and post-activity questions. Topics include period and amplitude, transverse and longitudinal wave motion, and motion of a pendulum. The instructional method is based on cognitive apprenticeship, in which students focus scientific process by observing, finding patterns, modeling, predicting, testing, and revising. The materials were designed to mirror the activities of scientists when they construct and apply knowledge. See Related Materials for links to the full collection by the same authors and for free access to an article explaining the theoretical basis for this instructional method.

Etkina, Eugenia

2011-11-18

91

Operational modal analysis in the presence of harmonic excitations by the use of transmissibility measurements  

NASA Astrophysics Data System (ADS)

Operational modal analysis (OMA) is based on the assumption that the forces on the structure are the result of a stochastic process, so being white noise. In practice, however, structural vibrations observed in operation cannot always be considered as pure white-noise excitation. In many mechanical structures the loading forces are often more complex and even harmonic components can be present in the response. This is especially true, when measuring on mechanical structures containing rotating parts (e.g. cars, turbines, windmills), but also civil engineering structures may have responses superimposed by harmonic components. OMA procedures are, strictly speaking, not applicable in these situations. Current techniques may encounter difficulties to correctly identify the modal parameters, especially for modes with eigenfrequencies close to the harmonic frequencies. In this paper a recently proposed OMA technique based on transmissibility measurements will be applied. This method reduces the risk to wrongly identify the modal parameters due to the presence of harmonics. The unknown operational forces can be arbitrary (coloured noise, swept sine, impact, etc.) as long as they are persistently exciting in the frequency band of interest.

Devriendt, Christof; De Sitter, Gert; Vanlanduit, Steve; Guillaume, Patrick

2009-04-01

92

Ultra-high degree spherical harmonic analysis and synthesis using extended-range arithmetic  

NASA Astrophysics Data System (ADS)

We present software for spherical harmonic analysis (SHA) and spherical harmonic synthesis (SHS), which can be used for essentially arbitrary degrees and all co-latitudes in the interval (0°, 180°). The routines use extended-range floating-point arithmetic, in particular for the computation of the associated Legendre functions. The price to be paid is an increased computation time; for degree 3,000, the extended-range arithmetic SHS program takes 49 times longer than its standard arithmetic counterpart. The extended-range SHS and SHA routines allow us to test existing routines for SHA and SHS. A comparison with the publicly available SHS routine GEOGFG18 by Wenzel and HARMONIC SYNTH by Holmes and Pavlis confirms what is known about the stability of these programs. GEOGFG18 gives errors <1 mm for latitudes [-89°57.5', 89°57.5'] and maximum degree 1,800. Higher degrees significantly limit the range of acceptable latitudes for a given accuracy. HARMONIC SYNTH gives good results up to degree 2,700 for almost the whole latitude range. The errors increase towards the North pole and exceed 1 mm at latitude 82° for degree 2,700. For a maximum degree 3,000, HARMONIC SYNTH produces errors exceeding 1 mm at latitudes of about 60°, whereas GEOGFG18 is limited to latitudes below 45°. Further extending the latitudinal band towards the poles may produce errors of several metres for both programs. A SHA of a uniform random signal on the sphere shows significant errors beyond degree 1,700 for the SHA program SHA by Heck and Seitz.

Wittwer, Tobias; Klees, Roland; Seitz, Kurt; Heck, Bernhard

2008-04-01

93

Quantization noise in digital signal processing by harmonic analysis in a synthetic-aperture radar  

Microsoft Academic Search

The paper derives and analyzes expressions for assessing the effect of quantization noise arising in digital signal processing by harmonic analysis in a synthetic-aperture radar on the output signal for an arbitrary weight function in an FFT processor. The output signal-to-noise ratio is shown to depend on the FFT base size, the digit-representation length in the processing system, and the

N. A. Sazonov

1985-01-01

94

Rigid mode and harmonic response analysis of three-body vibrating screen  

Microsoft Academic Search

By using the ADAMS, the dynamic parameters of three-body vibrating screen are extracted, and the simple finite element model is established on the basis of parameters in ANSYS. The amplitude-frequency curve and phase-frequency curve is obtained by using the harmonic analysis. According to the error between the simulated amplitude of the vibrating screen and the actual magnitude, the correctness of

Chuanguang Ding; Fangzhen Song; Bo Song

2011-01-01

95

Application of the homotopy analysis method for the Gross—Pitaevskii equation with a harmonic trap  

NASA Astrophysics Data System (ADS)

The Homotopy analysis method (HAM) is adopted to find the approximate analytical solutions of the Gross—Pitaevskii equation, a nonlinear Schrödinger equation is used in simulation of Bose—Einstein condensates trapped in a harmonic potential. Comparisons between the analytical solutions and the numerical solutions have been made. The results indicate that they fit very well with each other when the atomic interaction is weak.

Shi, Yu-Ren; Liu, Cong-Bo; Wang, Guang-Hui; Zhou, Zhi-Gang

2012-12-01

96

Reconstruction of the land surface temperature time series using harmonic analysis  

NASA Astrophysics Data System (ADS)

Satellite remote sensing is an important approach for obtaining land surface temperature (LST) over wide temporal and spatial ranges. However, the presence of clouds generates numerous missing and abnormal values that affect the application of LST data. To fill data gaps and improve data quality, the Harmonic ANalysis of Time Series (HANTS) algorithm was employed to remove cloud-affected observations and reconstruct the Moderate Resolution Imaging Spectroradiometer (MODIS) LST data taken in the year 2005 for the Yangtze River Delta region of China. Analysis of MODIS data quality indicated that the yearly proportion of high-quality LST data in this region was less than 50% with numerous missing and low-quality data points. To reconstruct 8-day LST via the removal of cloud-contaminated observations, we applied pixel-by-pixel harmonic fitting to the time series and used fitted values to replace the missing and abnormal values in the original LST data. To evaluate the reconstruction performance, a simulated dataset was generated according to the percentage of cloud coverage in each 8-day period. Satisfactory validation results indicate that the harmonic method can effectively fit the NA Values caused by cloud cover and fill data gaps in the LST data, which can significantly improve the practical value of the MODIS LST dataset.

Xu, Yongming; Shen, Yan

2013-12-01

97

A method for the harmonic removal in operational modal analysis of rotating blades  

NASA Astrophysics Data System (ADS)

The operational modal analysis, OMA, allows estimating the dynamic properties of a structure, natural frequencies, damping ratios, and mode shapes, without measuring the input forces. According to the main hypothesis concerning the input excitation, i.e., stochastic with frequency independent spectra (at least in the frequency band of interest), it is not theoretically possible to apply the OMA procedures in structures characterized by the presence of harmonic components in the excitation loading. In this paper, an approach capable to identify the presence of harmonic excitations, acting together with a broad band stochastic loading, and then to remove their effects in the modal parameter estimate is presented. The approach is based on the joint use of the statistical parameter called "entropy" and the already developed output-only procedure based on the application of the Hilbert transform properties to the output response signals. The capability to improve the OMA procedures is investigated numerically and through whirl tower experimental tests of a rotating blade in which both stochastic and harmonic contributions to the dynamic excitations have been provided by the perturbations arising from the operative conditions. A sensitivity analysis has been also performed to evaluate the effects of the filtered responses, in the time domain, on the statistical characterization, required to distinguish the operational frequencies from the natural ones.

Agneni, Alessandro; Coppotelli, Giuliano; Grappasonni, Chiara

2012-02-01

98

Surface alignment of 3D spherical harmonic models: application to cardiac MRI analysis.  

PubMed

The spherical harmonic (SPHARM) description is a powerful surface modeling technique that can model arbitrarily shaped but simply connected 3D objects and has been used in many applications in medical imaging. Previous SPHARM techniques use the first order ellipsoid for establishing surface correspondence and aligning objects. However, this first order information may not be sufficient in many cases; a more general method for establishing surface correspondence would be to minimize the mean squared distance between two corresponding surfaces. In this paper, a new surface matching algorithm is proposed for 3D SPHARM models to achieve this goal. This algorithm employs a useful rotational property of spherical harmonic basis functions for a fast implementation. Applications of medical image analysis (e.g., spatio-temporal modeling of heart shape changes) are used to demonstrate this approach. Theoretical proofs and experimental results show that our approach is an accurate and flexible surface correspondence alignment method. PMID:16685830

Huang, Heng; Shen, Li; Zhang, Rong; Makedon, Fillia; Hettleman, Bruce; Pearlman, Justin

2005-01-01

99

Advances in high-harmonic fast wave physics in the National Spherical Torus Experiment  

SciTech Connect

Improved core high-harmonic fast wave (HHFW) heating at longer wavelengths and during start-up and plasma current ramp-up has now been obtained by lowering the edge density with lithium wall conditioning, thereby moving the critical density for perpendicular fast-wave propagation away from the vessel wall. Lithium conditioning allowed significant HHFW core electron heating of deuterium neutral beam injection (NBI) fuelled H-mode plasmas to be observed for the first time. Large edge localized modes were observed immediately after the termination of rf power. Visible and infrared camera images show that fast wave interactions can deposit considerable rf energy on the outboard divertor. HHFW-generated parametric decay instabilities were observed to heat ions in the plasma edge and may be the cause for a measured drag on edge toroidal rotation during HHFW heating. A significant enhancement in neutron rate and fast-ion profile was measured in NBI-fuelled plasmas when HHFW heating was applied.

Taylor, G.; Bell, R. E.; Hosea, J. C.; LeBlanc, B. P.; Phillips, C. K.; Podesta, M.; Valeo, E. J.; Wilson, J. R. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Ahn, J-W.; Chen, G.; Green, D. L.; Jaeger, E. F.; Maingi, R.; Ryan, P. M.; Wilgen, J. B. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Heidbrink, W. W.; Liu, D. [University of California, Irvine, California 92697 (United States); Bonoli, P. T. [Plasma Science and Fusion Center, MIT, Massachusetts 02139 (United States); Brecht, T. [University of Minnesota, Minnesota 55455 (United States); Choi, M. [General Atomics, San Diego, California 92186 (United States)

2010-05-15

100

Advances in High-harmonic Fast Wave Physics in the National Spherical Torus Experiment  

SciTech Connect

Improved core high-harmonic fast wave (HHFW) heating at longer wavelengths and during start-up and plasma current ramp-up, has now been obtained by lowering the edge density with lithium wall conditioning, thereby moving the critical density for perpendicular fast-wave propagation away from the vessel wall. Lithium conditioning allowed significant HHFW core electron heating of deuterium neutral beam injection (NBI) fuelled H-mode plasmas to be observed for the first time. Large edge localized modes were observed immediately after the termination of rf power. Visible and infrared camera images show that fast wave interactions can deposit considerable rf energy on the outboard divertor. HHFW-generated parametric decay instabilities were observed to heat ions in the plasma edge and may be the cause for a measured drag on edge toroidal rotation during HHFW heating. A significant enhancement in neutron rate and fast-ion profile were measured in NBI-fuelled plasmas when HHFW heating was applied. __________________________________________________

Taylor, G; Hosea, J C; LeBlanc, B P; Phillips, C K; Podesta, M; Valeo, E J; Wilson, J R; Ahn, J -W; Chen, G; Green, D L; Jaeger, E F; Maingi, R; Ryan, P M; Wilgen, J B; Heidbrink, W W; Liu, D; Bonoli, P T; Brecht, T; Choi, M

2009-12-01

101

Advances in high-harmonic fast wave physics in the National Spherical Torus Experiment  

NASA Astrophysics Data System (ADS)

Improved core high-harmonic fast wave (HHFW) heating at longer wavelengths and during start-up and plasma current ramp-up has now been obtained by lowering the edge density with lithium wall conditioning, thereby moving the critical density for perpendicular fast-wave propagation away from the vessel wall. Lithium conditioning allowed significant HHFW core electron heating of deuterium neutral beam injection (NBI) fuelled H-mode plasmas to be observed for the first time. Large edge localized modes were observed immediately after the termination of rf power. Visible and infrared camera images show that fast wave interactions can deposit considerable rf energy on the outboard divertor. HHFW-generated parametric decay instabilities were observed to heat ions in the plasma edge and may be the cause for a measured drag on edge toroidal rotation during HHFW heating. A significant enhancement in neutron rate and fast-ion profile was measured in NBI-fuelled plasmas when HHFW heating was applied.

Taylor, G.; Bell, R. E.; Hosea, J. C.; Leblanc, B. P.; Phillips, C. K.; Podesta, M.; Valeo, E. J.; Wilson, J. R.; Ahn, J.-W.; Chen, G.; Green, D. L.; Jaeger, E. F.; Maingi, R.; Ryan, P. M.; Wilgen, J. B.; Heidbrink, W. W.; Liu, D.; Bonoli, P. T.; Brecht, T.; Choi, M.; Harvey, R. W.

2010-05-01

102

Random harmonic analysis program, L221 (TEV156). Volume 2: Supplemental system design and maintenenace document  

NASA Technical Reports Server (NTRS)

Volume 2 of a two volume document is presented. A computer program, L222 (TEV 156), available for execution on the CDC 6600 computer is described. The program is capable of calculating steady-state solutions for linear second-order differential equations due to sinusoidal forcing functions. From this, steady-state solutions, generalized coordinates, and load frequency responses may be determined. Statistical characteristics of loads for the forcing function spectral shape may also be calculated using random harmonic analysis techniques. The particular field of application of the program is the analysis of airplane response and loads due to continuous random air turbulence.

Graham, M. L.; Clemmons, R. E.; Miller, R. D.

1979-01-01

103

Discovering new physics in magnetic thin films using coherent EUV from high harmonic generation  

NASA Astrophysics Data System (ADS)

The understanding of nanoscale magnetism has become much more critical with recent advances in magnetic data storage applications, as bits on a hard disk are already packed at scales of about 20nm. However, a microscopic model of how spins, electrons, photons and phonons interact does not yet exist. This understanding is fundamentally constrained in large part by our limited ability to observe magnetism on all relevant time and length scales. Until recently, measuring magnetization dynamics used either ultrafast visible-wavelength lasers, or X-rays from synchrotrons and free electron lasers. Our recent work has shown that the fastest dynamics in magnetic materials can be captured using extreme ultraviolet (XUV) harmonics -- with elemental resolution and at multiple atomic sites simultaneously. We first probed with elemental sensitivity how fast the magnetic state can be destroyed in an Fe-Ni alloy. After exciting an Fe-Ni alloy with a fs laser, the spin sublattices randomize on sub-ps timescales. Surprisingly, even in a strongly coupled ferromagnetic alloy, the demagnetization of Ni lags that of Fe by 10 fs [1]. Moreover, we were able to tune this time lag by diluting the alloy with Cu to further reduce the exchange energy. After a time lag characteristic of the exchange energy, the Ni sublattice demagnetizes at the same rate as Fe. This reveals both how the exchange interaction can mediate ultrafast magnetic dynamics in alloys, and how the intrinsic demagnetization process is site-specific such that spins on one sublattice can interact more strongly with the optical field than spins on the other sublattice. In our latest work, we uncovered evidence of giant spin-currents in magnetic multilayers that are generated in the course of the laser-driven ultrafast demagnetization process [2]. By exciting a magnetic multilayer (Fe/Ru/Ni) with a laser pulse, and separately, yet simultaneously, probing the magnetization response of the Ni and Fe layers when the two layers are aligned with an applied magnetic field, we found that optically induced demagnetization of the top Ni layer causes the buried Fe layer to undergo a transient enhancement of the magnetization, of up to 20 percent. This is due to an intense, majority spin-current that enters the Fe layer. [4pt] [1] S. Mathias, et al., PNAS 109, (2012).[0pt] [2] D. Rudolf, et al., Nat. Comm. 3, (2012).

Silva, Tom

2013-03-01

104

Fourier Analysis in Introductory Physics  

ERIC Educational Resources Information Center

In an after-dinner talk at the fall 2005 meeting of the New England chapter of the AAPT, Professor Robert Arns drew an analogy between classical physics and Classic Coke. To generations of physics teachers and textbook writers, classical physics was the real thing. Modern physics, which in introductory textbooks "appears in one or more extra…

Huggins, Elisha

2007-01-01

105

Effective medium multipolar tensor analysis of second-harmonic generation from metal nanoparticles  

NASA Astrophysics Data System (ADS)

We present a detailed multipolar tensor analysis of second-harmonic (SH) generation from arrays of L-shaped gold nanoparticles. We define three effective nonlinear tensors, which include electric dipoles only (Aeee) and lowest-order magnetic (and quadrupole) effects at the fundamental (Aeem) and the SH (Amee) frequency. The components of the various tensors are distinguished through their different transformations as the experimental geometry is varied. The response is dominated by electric-dipole effects. However, the higher multipoles also play a significant role and are more important at the fundamental frequency than at the SH frequency. The results correlate well with the particles' plasmonic resonances and symmetry rules.

Zdanowicz, Mariusz; Kujala, Sami; Husu, Hannu; Kauranen, Martti

2011-02-01

106

A Comparison of Spherical Harmonics and Slepian Basis Functions in Magnetic Field Analysis  

NASA Astrophysics Data System (ADS)

Planetary probes often have equatorial, low inclination, orbits around the planet in question, leaving polar data gaps. For example, the orbital path of the Cassini probe around Saturn is essentially limited to a narrow latitudinal band around the equator. For potential field studies this can lead to problems as such studies traditionally employ spherical harmonics, which require global support, to describe the potential field (Simons 2006, Simons 2006a, Wieczorek 2005). Here we consider the use of different basis functions that have been specifically designed to deal with such situations. In contrast to using spherical harmonics for a spectral representation of such 'equatorial' data, an approach which can be prone to errors because global support is required to achieve orthogonality over the whole sphere, Slepian functions, which are orthogonal over both the whole sphere and the region of data coverage, and which have their energy optimally concentrated in the spatial and spectral domain, should yield better results. We have set out to compare the use of these new basis functions in magnetic field analysis with the canonical spherical harmonics. Are the Slepian basis functions better for resolving the magnetic field? Such comparisons have been done in the past, (Simons 2006, Simons 2006a) but took a more theoretical stance, evaluating only a bandlimited white noise source field. We are more interested in the performance under practical circumstances. We employ a number of criteria to evaluate the performance of both basis functions such as: errors, variances, spectral leakage. We have used an Earth magnetic field model, POMME, to generate realistic magnetic field values and Cassini's trajectory scaled to Earth to generate typical equatorial coverage. Simons, F., Dahlen, F., 2006. Spherical Slepian functions and the polar gap in geodesy. Geophysical Journal International 166(3). Simons, F., Dahlen, F., Wieczorek, M. A., 2006. Spatiospectral concentration on a sphere. SIAM Review 48(3). Wieczorek, M., Simons, F., 2005. Localized spectral analysis on the sphere. Geophysical Journal International 162.

Boxham, J.; Sterenborg, M. G.

2008-12-01

107

Tools for Physics Analysis in CMS  

NASA Astrophysics Data System (ADS)

The CMS Physics Analysis Toolkit (PAT) is presented. The PAT is a high-level analysis layer enabling the development of common analysis efforts across and within physics analysis groups. It aims at fulfilling the needs of most CMS analyses, providing both ease-of-use for the beginner and flexibility for the advanced user. The main PAT concepts are described in detail and some examples from realistic physics analyses are given.

Hinzmann, Andreas

2011-12-01

108

A Back-to-Front Derivation: The Equal Spacing of Quantum Levels Is a Proof of Simple Harmonic Oscillator Physics  

ERIC Educational Resources Information Center

The dynamical behaviour of simple harmonic motion can be found in numerous natural phenomena. Within the quantum realm of atomic, molecular and optical systems, two main features are associated with harmonic oscillations: a finite ground-state energy and equally spaced quantum energy levels. Here it is shown that there is in fact a one-to-one…

Andrews, David L.; Romero, Luciana C. Davila

2009-01-01

109

Fourier Analysis in Introductory Physics  

NASA Astrophysics Data System (ADS)

In an after-dinner talk at the fall 2005 meeting of the New England chapter of the AAPT, Professor Robert Arns drew an analogy between classical physics and Classic Coke. To generations of physics teachers and textbook writers, classical physics was the real thing. Modern physics, which in introductory textbooks ``appears in one or more extra chapters at the end of the book, ... is a divertimento that we might get to if time permits.'' Modern physics is more like vanilla or lime Coke, probably a fad, while ``Classic Coke is part of your life; you do not have to think about it twice.''

Huggins, Elisha

2007-01-01

110

Physics of Baseball Bats - An Analysis  

Microsoft Academic Search

An analysis of the physics of baseball bats is presented in this study. The analysis compares the performance of aluminum and wooden baseball bats. Novel experimental approaches to indirectly quantify the performance of these bats have been implemented. The analysis also considers various aspects of baseball including the physical dimensions of the baseball fields, ball exit speed ratio, moment of

N. M. Ravindra; Sushil K. Sikh; Ivan Padron

2009-01-01

111

An integral equation analysis of the harmonic response of three-layer beams  

NASA Astrophysics Data System (ADS)

The integral equations of harmonic motion have been derived and solved for three-layer sandwich beams with a constrained linear viscoelastic core. The method of solution required first the construction of the Green's vector for a beam in analytical form. Following this, the integral equations were derived and readily approximated by matrix equations which were finally solved numerically. In addition to this analysis, the corresponding eigenvalue problem has been solved so that the modal frequencies and the beam loss factor could be calculated directly. The integral equation analysis offers a fast and efficient alternative to the traditional methods based on the solution of the differential equations of motion. The method has been verified by comparison with experimental results for three-layer cantilevers and simply supported beams.

Ioannides, E.; Grootenhuis, P.

1982-05-01

112

Digital pathology and image analysis augment biospecimen annotation and biobank quality assurance harmonization.  

PubMed

Standardization of biorepository best practices will enhance the quality of translational biomedical research utilizing patient-derived biobank specimens. Harmonization of pathology quality assurance procedures for biobank accessions has lagged behind other avenues of biospecimen research and biobank development. Comprehension of the cellular content of biorepository specimens is important for discovery of tissue-specific clinically relevant biomarkers for diagnosis and treatment. While rapidly emerging technologies in molecular analyses and data mining create focus on appropriate measures for minimizing pre-analytic artifact-inducing variables, less attention gets paid to annotating the constituent makeup of biospecimens for more effective specimen selection by biobank clients. Both pre-analytic tissue processing and specimen composition influence acquisition of relevant macromolecules for downstream assays. Pathologist review of biorepository submissions, particularly tissues as part of quality assurance procedures, helps to ensure that the intended target cells are present and in sufficient quantity in accessioned specimens. This manual procedure can be tedious and subjective. Incorporating digital pathology into biobank quality assurance procedures, using automated pattern recognition morphometric image analysis to quantify tissue feature areas in digital whole slide images of tissue sections, can minimize variability and subjectivity associated with routine pathologic evaluations in biorepositories. Whole-slide images and pathologist-reviewed morphometric analyses can be provided to researchers to guide specimen selection. Harmonization of pathology quality assurance methods that minimize subjectivity and improve reproducibility among collections would facilitate research-relevant specimen selection by investigators and could facilitate information sharing in an integrated network approach to biobanking. PMID:24362266

Wei, Bih-Rong; Simpson, R Mark

2014-03-01

113

Analysis of parameter sensitivity of space manipulator with harmonic drive based on the revised response surface method  

NASA Astrophysics Data System (ADS)

Space manipulator is an important tool for spacecraft to complete a variety of tasks in space. Nowadays the harmonic drive is widely used as the reducer in the space manipulator, which may influence the dynamical properties of flexible space manipulator. The analysis of dynamic reliability and parameter sensitivity of space manipulator with harmonic drive is of significant importance for space manipulator designers in the early stage of design. The trajectory precision of the manipulator determines whether the mechanism performs normally. However, it is difficult to use the existing methods to resolve reliability apportionment issues because of the data insufficiency and the uncertainty of the relations among the components in the mechanical system. This paper establishes the dynamical models of space manipulator considering the harmonic hysteresis phenomenon derived from the harmonic reducer. A new method is proposed to analyze the dynamic reliability and parameter sensitivity of space manipulator with harmonic drive. The proposed method extends the previous response surface method (RSM) and focuses on the characteristics of the output dynamical property of the space manipulator. With the result of parameter sensitivity analysis, we can prolong the fine arm or shorten the main arm to improve the motion precision reliability of space manipulator. Therefore, our revised response surface method (RRSM) is suitable for reliability apportionment of the space manipulator when the design information has not been clearly identified, particularly in early design phrase.

Zhao, Jieliang; Yan, Shaoze; Wu, Jianing

2014-05-01

114

Higher harmonic control analysis for vibration reduction of helicopter rotor systems  

NASA Technical Reports Server (NTRS)

An advanced higher harmonic control (HHC) analysis has been developed and applied to investigate its effect on vibration reduction levels, blade and control system fatigue loads, rotor performance, and power requirements of servo-actuators. The analysis is based on a finite element method in space and time. A nonlinear time domain unsteady aerodynamic model, based on the indicial response formulation, is used to calculate the airloads. The rotor induced inflow is computed using a free wake model. The vehicle trim controls and blade steady responses are solved as one coupled solution using a modified Newton method. A linear frequency-domain quasi-steady transfer matrix is used to relate the harmonics of the vibratory hub loads to the harmonics of the HHC inputs. Optimal HHC is calculated from the minimization of the vibratory hub loads expressed in term of a quadratic performance index. Predicted vibratory hub shears are correlated with wind tunnel data. The fixed-gain HHC controller suppresses completely the vibratory hub shears for most of steady or quasi-steady flight conditions. HHC actuator amplitudes and power increase significantly at high forward speeds (above 100 knots). Due to the applied HHC, the blade torsional stresses and control loads are increased substantially. For flight conditions where the blades are stalled considerably, the HHC input-output model is quite nonlinear. For such cases, the adaptive-gain controller is effective in suppressing vibratory hub loads, even though HHC may actually increase stall areas on the rotor disk. The fixed-gain controller performs poorly for such flight conditions. Comparison study of different rotor systems indicates that a soft-inplane hingeless rotor requires less actuator power at high speeds (above 130 knots) than an articulated rotor, and a stiff-inplane hingeless rotor generally requires more actuator power than an articulated or a soft-inplane hingeless rotor. Parametric studies for a hingeless rotor operating in a transition flight regime and for an articulated rotor operating at the level-flight boundary (high speed and high thrust conditions) indicate that blade parameters including flap, lag, torsion stiffness distributions, linear pretwist, chordwise offset of center-of-mass from elastic axis and chordwise offset of elastic axis from aerodynamic center can be selected to minimize the actuator power requirements for HHC.

Nguyen, Khanh Q.

1994-01-01

115

Electromagnetic Interference Analysis Based on Total Harmonic Distortion Measurement in 900MHz Cordless Telephones  

NASA Astrophysics Data System (ADS)

In this paper a new electromagnetic (EM) interference analysis is proposed using the total harmonic distortion (THD) measurement of the audio signal by the 900MHz cordless telephones. The cordless telephone network in 900MHz was built up to be weak in EM interference. 400 and 800Hz of the sine-wave signal were used in transmitter (TX) system, and the receiver (RX) system was exposed to the EM interference. The THD value varies as the level of the exposed EM interference changes. The model of the cordless telephone also affects the THD value. By using fluctuation of the THD value depending on the amount of the exposure, the threshold value of the interference electric field strength was derived. Based on the derived threshold value of the electric field strength, validity of the regulation value for low power radio devices by CISPR 22 [CLASS B] and FCC is discussed.

Park, Jeung Geun; Kim, Che Young

116

Work distribution in a time-dependent logarithmic-harmonic potential: exact results and asymptotic analysis  

NASA Astrophysics Data System (ADS)

We investigate the distribution of work performed on a Brownian particle in a time-dependent asymmetric potential well. The potential has a harmonic component with a time-dependent force constant and a time-independent logarithmic barrier at the origin. For an arbitrary driving protocol, the problem of solving the Fokker-Planck equation for the joint probability density of work and particle position is reduced to the solution of the Riccati differential equation. For a particular choice of the driving protocol, an exact solution of the Riccati equation is presented. An asymptotic analysis of the resulting expression yields the tail behavior of the work distribution for small and large work values. In the limit of a vanishing logarithmic barrier, the work distribution for the breathing parabola model is obtained.

Ryabov, Artem; Dierl, Marcel; Chvosta, Petr; Einax, Mario; Maass, Philipp

2013-02-01

117

Analysis of spatial lamellar distribution from adaptive-optics second harmonic generation corneal images  

PubMed Central

The spatial organization of stromal collagen of ex-vivo corneas has been quantified in adaptive-optics second harmonic generation (SHG) images by means of an optimized Fourier transform (FT) based analysis. At a particular depth location, adjacent lamellae often present similar orientations and run parallel to the corneal surface. However this pattern might be combined with interweaved collagen bundles leading to crosshatched structures with different orientations. The procedure here reported provides us with both principal and crosshatched angles. This is also able to automatically distinguish a random distribution from a cross-shaped one, since it uses the ratio of the axes lengths of the best-fitted ellipse of the FT data as an auxiliary parameter. The technique has successfully been applied to SHG images of healthy corneas (both stroma and Bowman’s layer) of different species and to corneas undergoing cross-linking treatment.

Bueno, Juan M.; Palacios, Raquel; Chessey, Mary K.; Ginis, Harilaos

2013-01-01

118

A Theoretical Analysis of the Harmonic Content of PWM Waveforms for Multiple-Frequency Modulators  

Microsoft Academic Search

This paper theoretically identifies the harmonic components of a carrier-based pulsewidth-modulated (PWM) voltage-source converter (VSC) output voltage when the modulating wave includes fundamental and baseband harmonic components. This occurs, for example, when a VSC is used as an active power filter. The general analytical solution provided can be applied with a minimum additional mathematical effort to any harmonic combination in

Milijana Odavic; Mark Sumner; Pericle Zanchetta; Jon C. Clare

2010-01-01

119

An Analysis of Shot Noise Propagation and Amplificationin Harmonic Cascade FELs  

SciTech Connect

The harmonic generation process in a harmonic cascade (HC) FEL is subject to noise degradation which is proportional to the square of the total harmonic order. In this paper, we study the shot noise evolution in the first-stage modulator and radiator of a HC FEL that produces the dominant noise contributions. We derive the effective input noise for a modulator operating in the low-gain regime, and analyze the radiator noise for a density-modulated beam. The significance of these noise sources in different harmonic cascade designs is also discussed.

Huang, Z.; /SLAC

2006-12-11

120

Harmonic Drive.  

National Technical Information Service (NTIS)

The harmonic drive has utility in optical tracking telescopes, radar antenna drives, aircraft control surface actuators, and high precision X-Y plotting equipment. Two harmonic drive units, each having its own input motor, are coupled together. One of the...

R. H. Lapp

1965-01-01

121

Oceanic lithospheric magnetisation: Forward modelling and analysis using vector spherical harmonics (Invited)  

NASA Astrophysics Data System (ADS)

The lithospheric contribution to the geomagnetic field arises from magnetised rocks that are cooler than the Curie temperature of their constituent minerals. Inversion of the magnetic field for this magnetisation is subject to inherent non-uniqueness, as many magnetisation distributions yield no potential field outside of the lithosphere. Such distributions are termed annihilators. We use a complete set of orthogonal vector spherical harmonics that separate the part of the magnetisation responsible for the magnetic field observed above the Earth's surface from the annihilators. A similar set of vector harmonics has been developed in Cartesian geometry suitable for small scale, industrial applications. In an attempt to quantify the significance of the annihilators, we first construct a global model of vertically integrated magnetisation (VIM) by combining a model of remanent magnetisation for the oceans with a previous model of induced magnetisation for the whole Earth. Remanence is computed by assigning magnetisations to the oceanic lithosphere acquired at the location and time of formation. The magnetising field is assumed to be an axial dipole that switches polarity with the reversal time scale. The magnetisation evolves with time by decay of thermal remanence and acquisition of chemical remanence. Remanence directions are calculated by implementing finite rotations of the original geomagnetic field direction with respect to an absolute reference frame. We then represent our estimated VIM in terms of vector spherical harmonics, to allow us to evaluate its relative contributions to a potential field that is observable outside of the lithosphere and to fields (both potential and non-potential) that are not observable. This analysis shows that our model of magnetisation is dominated by a part of the magnetisation that produces a potential field restricted to Earth's sub-lithospheric interior; it therefore contributes significantly to the huge null space in the inversion of lithospheric magnetic anomaly data for VIM. We calculate the observable potential field that arises from our magnetisation estimates and compare it with a model that is based upon satellite data (MF7); this allows us to evaluate our magnetisation estimates and suggest likely sources of error in areas with high misfit between our predictions and the observed magnetic field. For example, under-prediction of the observed magnetic field may be indicative of poorly-known magnetisation deep in the crust or upper mantle, locally underplated continental lithosphere or anomalous oceanic crust.

Masterton, S. M.; Gubbins, D.; Müller, D.; Williams, S.

2013-12-01

122

Non-linear modeling of a broadband SLIC for ADSL-Lite-over-POTS using harmonic analysis  

Microsoft Academic Search

A new frequency domain based identification algorithm for the discrete-time Wiener model is presented. The Wiener model belongs to the class of Volterra models with factorizable kernels. Opposed to the general Volterra model, it is shown that the Wiener model can be uniquely identified, using harmonic analysis only. Therefore the given identification scheme is very suitable for real world applications,

H. Koeppl; G. Paoli

2002-01-01

123

A detailed instantaneous harmonic and reactive compensation analysis of three-phase AC\\/DC converters, in abc and ?? coordinates  

Microsoft Academic Search

This paper presents a digital simulation of an active filter, in which the instantaneous harmonic and reactive compensating currents are desegregated in their different ?? space-trajectories, and in their time-domain waveforms of both the abc and the ?? system of coordinates. Departing from Akagi's generalized instantaneous reactive power theory, a complete analysis is presented, in which the counterharmonic compensating current

Alfredo Nava-Segura; M. Carmona-Hernandez

1998-01-01

124

A detailed instantaneous harmonic and reactive compensation analysis of three-phase AC\\/DC converters, in abc and ?? coordinates  

Microsoft Academic Search

Summary form only as given. This paper presents a digital simulation of an active filter, in which the instantaneous harmonic and reactive compensating currents are desegregated in their different ?? space-trajectories, and in their time-domain waveforms of both the abc and the ?? system of coordinates. Departing from Akagi's generalized instantaneous reactive power theory, a complete analysis is presented, in

A. Nava-Segura; M. Carmona-Hernandez

1999-01-01

125

ACCURATE SHORT-TERM ANALYSIS OF THE FUNDAMENTAL FREQUENCY AND THE HARMONICS-TO-NOISE RATIO OF A SAMPLED SOUND  

Microsoft Academic Search

We present a straightforward and robust algorithm for periodicity detection, working in the lag (autocorrelation) domain. When it is tested for periodic signals and for signals with additive noise or jitter, it proves to be several orders of magnitude more accurate than the methods commonly used for speech analysis. This makes our method capable of measuring harmonics-to-noise ratios in the

Paul Boersma

1993-01-01

126

High-order harmonic generation in diatomic molecules: A quantum-orbit analysis of the interference patterns  

SciTech Connect

We perform a detailed analysis of high-order harmonic generation in diatomic molecules within the strong-field approximation (SFA), with emphasis on quantum-interference effects. Specifically, we investigate how the different types of electron orbits, involving one or two centers, affect the interference patterns in the spectra. We also briefly address the influence of the choice of gauge and of the initial and final electronic bound states on such patterns. For the length-gauge SFA and undressed bound states, there exist additional terms, which can be interpreted as potential energy shifts. If, on the one hand, such shifts alter the potential barriers through which the electron initially tunnels, and may lead to a questionable physical interpretation of the features encountered, on the other hand, they seem to be necessary in order to reproduce the overall maxima and minima in the spectra. Indeed, for dressed electronic bound states in the length gauge, or undressed bound states in the velocity gauge, for which such shifts are absent, there is a breakdown of the interference patterns. In order to avoid such a problem, we provide an alternative pathway for the electron to reach the continuum, by means of an additional attosecond-pulse train. A comparison of the purely monochromatic case with the situation for which the attosecond pulses are present suggests that the patterns are due to the interference between the electron orbits which finish at different centers, regardless of whether one or two centers are involved.

Figueira de Morisson Faria, C. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

2007-10-15

127

Error and symmetry analysis of Misner's algorithm for spherical harmonic decomposition on a cubic grid  

Microsoft Academic Search

Computing spherical harmonic decompositions is a ubiquitous technique that arises in a wide variety of disciplines and a large number of scientific codes. Because spherical harmonics are defined by integrals over spheres, however, one must perform some sort of interpolation in order to compute them when data are stored on a cubic lattice. Misner (2004 Class. Quantum Grav.21 S243) presented

David R. Fiske

2006-01-01

128

Harmonic distortion in intracochlear pressure and its analysis to explore the cochlear amplifier  

NASA Astrophysics Data System (ADS)

Intracochlear pressure was measured close to the basal basilar membrane in gerbil with pure-tone stimulation. This report describes harmonic distortion in the pressure. The harmonic components were tuned in frequency and physiologically vulnerable, implying that they were related to the cell-derived force that sharpens tuning at low levels in healthy cochleae. For stimulus frequencies in the vicinity of the best frequency the harmonic distortion appeared to be produced locally, at the place of measurement. Therefore, it could be explored with a local nonlinear model. The combined model and observations demonstrate two specific points: First, the harmonics in the cell-based force were likely similar in size to the harmonics in pressure (multiplied by area) close to the basilar membrane. This is distinctly different than the situation for the fundamental component, where the cell-based force is apparently much smaller than the pressure (times area). Second, although the fundamental component of the measured pressure was much larger than its harmonic components, the harmonic and fundamental components of the active force were likely much more similar in size. This allows the harmonic components in the pressure to be used as an indirect measure of the active force.

Olson, Elizabeth S.

2004-03-01

129

The analysis of harmonic generation of SVC and STATCOM by EMTDC\\/PSCAD simulations  

Microsoft Academic Search

In the paper, the harmonic generation of the conventional SVC and modern STATCOM systems is analysed. At the beginning, short description of the SVC and STATCOM systems is given. Then assumed models of a power system, the SVC and STATCOM systems are described. After scope of the investigations is given, results of harmonic analyses are presented. The SVC and STATCOM

Kazimierz Wilkosz; Marian Sobierajski; Wiesl-aw KwaSnicki

1998-01-01

130

Elementary classical analysis of optical harmonic generation and four-wave mixing in strong light fields  

NASA Astrophysics Data System (ADS)

Simple classical models of optical harmonic generation in excited atomic systems with Coulomb and Debye interaction are considered. The influence of the effective potential on the shape of the spectrum and properties of optical harmonics is studied. Polarization effects in coherent four-wave mixing are analyzed.

Akimov, D. A.; Ferrante, G.; Koroteev, Nikolai I.; Zarcone, M.; Zheltikov, Alexei M.

1996-05-01

131

Analysis of harmonic and transient phenomena due to operation of a-c arc furnace  

Microsoft Academic Search

Operation of an a-c electric arc furnace load is associated with the generation of harmonic currents in the frequency range of fractions of Hertz up to approximately 1,000 Hz. The magnitude of these harmonic current components can be high and depends on the diverse operating condition of the system. Exposure of the furnace yard electrical components to overvoltages and overcurrents

A. Sarshar; M. Sharp; R. M. Iravani

1995-01-01

132

On the use of windows for harmonic analysis with the discrete Fourier transform  

Microsoft Academic Search

This paper makes available a concise review of data windows and their affect on the detection of harmonic signals in the presence of broad-band noise, and in the presence of nearby strong harmonic interference. We also call attention to a number of common errors in the application of windows when used with the fast Fourier transform. This paper includes a

FREDRIC J. HARRIS

1978-01-01

133

Multiple sets of solutions for harmonic elimination PWM bipolar waveforms: analysis and experimental verification  

Microsoft Academic Search

Multiple sets of solutions for the selective harmonic elimination pulse-width modulation method for inverter control exist. These sets present an independent solution to the same problem but further investigation reveals that certain sets may offer an improved overall harmonic performance. In this paper, a minimization method is discussed as a way to obtain these multiple sets of switching angles. A

Vassilios G. Agelidis; Anastasios Balouktsis; Ioannis Balouktsis; Calum Cossar

2006-01-01

134

Simulation model and harmonic analysis of SS6b electric locomotive based on PSCAD\\/EMTDC  

Microsoft Academic Search

Electric locomotive traction load is the main source of harmonics in traction power system and harmonic content has become an important electrical performance index. This paper adopts the PSCAD\\/EMTDC simulation software to establish simulation model of the SS6B electric locomotive. We can determine the firing angle through the relationship between traction characteristics function and commutating circuit in the electric locomotive.

Gao Lin; Xu Yonghai; Xiao Xiangnin; Jiang Peisi; Zhang Yunyan

2008-01-01

135

[Simulation and analysis of second-harmonic signal based on tunable diode laser absorption spectroscopy].  

PubMed

Tunable diode laser absorption spectroscopy (TDLAS) is a new gas detection technique developed recently with high spectral resolution, high sensitivity and fast time response. The second-harmonic signal of wavelength modulation spectroscopy (WMS) is often used as the detection signal for gas concentration inversion. Using Simulink, a visual modeling and simulation platform, the authors simulated the WMS signal based on TDLAS, and got the second-harmonic signal by using lock-in amplifier algorithm. Digital orthogonal algorithm was studied in this paper. The relationship between second-harmonic signals and the modulation indexes was analyzed by comparing changes of second-harmonic under different modulation indexes, in order to find out the optimized parameters for second-harmonic detection. PMID:23841390

Li, Han; Liu, Jian-Guo; He, Ya-Bai; He, Jun-Feng; Yao, Lu; Xu, Zhen-Yu; Chen, Jiu-Ying; Yuan, Song; Kan, Rui-Feng

2013-04-01

136

Application of harmonic analysis of water levels to determine vertical hydraulic conductivities in clay-rich aquitards.  

PubMed

A harmonic analysis method was used to determine vertical hydraulic conductivities (Kv) in geologic media between vertically separated piezometers using water level measurements. In this method, each water level time series was filtered and then decomposed using harmonic analysis into a sum of trigonometric components. The phase and amplitude of each harmonic function were calculated. These data were used to estimate Kv values between vertically separated data sets assuming one-dimensional transient flow. The method was applied to water level data collected from nested piezometers at two thick clay-rich till aquitards in Saskatchewan, Canada. At one site, routine water levels were measured in 12 piezometers (installed between 1 and 29 m below ground surface) since installation (1995). At the other site, water levels were measured in seven piezometers (installed between 4 and 53 m below ground surface) since installation (1998-1999). The Kv calculated using harmonic analysis decreased with depth below the water table at both sites, approaching matrix estimates of hydraulic conductivity between 10 and 11 m and between 21 and 43 m below ground surface. These depths reflected the depth of extensive vertical fracturing at the sites and showed that the depth of fracturing may be site specific. PMID:12873014

Boldt-Leppin, Brigitte E J; Hendry, M Jim

2003-01-01

137

A development environment for visual physics analysis  

NASA Astrophysics Data System (ADS)

The Visual Physics Analysis (VISPA) project integrates different aspects of physics analyses into a graphical development environment. It addresses the typical development cycle of (re-)designing, executing and verifying an analysis. The project provides an extendable plug-in mechanism and includes plug-ins for designing the analysis flow, for running the analysis on batch systems, and for browsing the data content. The corresponding plug-ins are based on an object-oriented toolkit for modular data analysis. We introduce the main concepts of the project, describe the technical realization and demonstrate the functionality in example applications.

Bretz, H.-P.; Brodski, M.; Erdmann, M.; Fischer, R.; Hinzmann, A.; Klimkovich, T.; Klingebiel, D.; Komm, M.; Lingemann, J.; Müller, G.; Münzer, T.; Rieger, M.; Steggemann, J.; Winchen, T.

2012-08-01

138

Using physical activity for user behavior analysis  

Microsoft Academic Search

Physical activity is one important aspect in user behavior analysis. Abnormal movement behavior might be an indicator for an inappropriate lifestyle, insufficient social inclusion, or generally disadvantageous life conditions which might call for medical treatment. Assistive technologies can make use of information on the physical activity of e.g. residents of a nursing home or elderly patients living alone at home.

Gerald Bieber; Christian Peter

2008-01-01

139

Finite Element Three-Dimensional Nonlinear Transient Analysis of the Shaded Pole Motor with Emphasis on Harmonics Analysis.  

NASA Astrophysics Data System (ADS)

A finite element method is used to analyze the characteristics and performance of a shaded pole motor. The importance of the spacial harmonics are investigated by finding the trajectory (locus) of spacial harmonics in the air-gap. The possibility of developing a reliable method for analyzing the shaded pole motor is investigated by attempt to express the nonuniform rotating field in the air-gap in terms of uniform forward and backward rotating fields. Quantities that are hard to measure like induced current in shading rings are calculated from the results of the study. From the study of design parameter variation, the significant parameters and their effect on the characteristics of the shaded pole motor are identified. Numerical results are then used to optimize the stall torque. The possibility of improving the conventional method of analysis is demonstrated by calculating lumped circuit elements by the finite element method. Based on the optimization findings of the sample motor, recommendations are made for the improvement of the performance of the shaded pole motor.

Sadeghi, Hamid Reza

140

Non-Characteristic Harmonics Analysis of the ITER Pulsed Power Supply  

NASA Astrophysics Data System (ADS)

The ITER pulsed power supply system will be operated in non-ideal conditions including an asymmetric firing angle, an unbalanced AC supply and an unbalanced AC side impedance of the transformer. In this study the switching functions approach is used to calculate non-characteristic harmonics in ITER, possibly caused by an AC-DC convertor in non-ideal conditions. A PSCAD simulation model is set up to study the non-characteristic harmonics in those non-ideal conditions. It is found that the non-characteristic harmonic does appear and the simulation result is in accordance with the calculating strategy.

Yang, Wei; Xu, Liuwei; Fu, Peng; Lu, Huawei; Sheng, Zhicai

2009-08-01

141

RUSHMAPS: Real-Time Uploadable Spherical Harmonic Moment Analysis for Particle Spectrometers  

NASA Technical Reports Server (NTRS)

RUSHMAPS is a new onboard data reduction scheme that gives real-time access to key science parameters (e.g. moments) of a class of heliophysics science and/or solar system exploration investigation that includes plasma particle spectrometers (PPS), but requires moments reporting (density, bulk-velocity, temperature, pressure, etc.) of higher-level quality, and tolerates a lowpass (variable quality) spectral representation of the corresponding particle velocity distributions, such that telemetry use is minimized. The proposed methodology trades access to the full-resolution velocity distribution data, saving on telemetry, for real-time access to both the moments and an adjustable-quality (increasing quality increases volume) spectral representation of distribution functions. Traditional onboard data storage and downlink bandwidth constraints severely limit PPS system functionality and drive cost, which, as a consequence, drives a limited data collection and lower angular energy and time resolution. This prototypical system exploit, using high-performance processing technology at GSFC (Goddard Space Flight Center), uses a SpaceCube and/or Maestro-type platform for processing. These processing platforms are currently being used on the International Space Station as a technology demonstration, and work is currently ongoing in a new onboard computation system for the Earth Science missions, but they have never been implemented in heliospheric science or solar system exploration missions. Preliminary analysis confirms that the targeted processor platforms possess the processing resources required for realtime application of these algorithms to the spectrometer data. SpaceCube platforms demonstrate that the target architecture possesses the sort of compact, low-mass/power, radiation-tolerant characteristics needed for flight. These high-performing hybrid systems embed unprecedented amounts of onboard processing power in the CPU (central processing unit), FPGAs (field programmable gate arrays), and DSP (digital signal processing) elements. The fundamental computational algorithm de constructs 3D velocity distributions in terms of spherical harmonic spectral coefficients (which are analogous to a Fourier sine-cosine decomposition), but uses instead spherical harmonics Legendre polynomial orthogonal functions as a basis for the expansion, portraying each 2D angular distribution at every energy or, geometrically, spherical speed-shell swept by the particle spectrometer. Optionally, these spherical harmonic spectral coefficients may be telemetered to the ground. These will provide a smoothed description of the velocity distribution function whose quality will depend on the number of coefficients determined. Successfully implemented on the GSFC-developed processor, the capability to integrate the proposed methodology with both heritage and anticipated future plasma particle spectrometer designs is demonstrated (with sufficiently detailed design analysis to advance TRL) to show specific science relevancy with future HSD (Heliophysics Science Division) solar-interplanetary, planetary missions, sounding rockets and/or CubeSat missions.

Figueroa-Vinas, Adolfo

2013-01-01

142

Advanced Analysis Methods in High Energy Physics  

SciTech Connect

During the coming decade, high energy physics experiments at the Fermilab Tevatron and around the globe will use very sophisticated equipment to record unprecedented amounts of data in the hope of making major discoveries that may unravel some of Nature's deepest mysteries. The discovery of the Higgs boson and signals of new physics may be around the corner. The use of advanced analysis techniques will be crucial in achieving these goals. The author discusses some of the novel methods of analysis that could prove to be particularly valuable for finding evidence of any new physics, for improving precision measurements and for exploring parameter spaces of theoretical models.

Pushpalatha C. Bhat

2001-10-03

143

Cosmic physics data analysis program  

NASA Technical Reports Server (NTRS)

A data analysis program was carried out to investigate the intensity, propagation, and origin of primary Cosmic Ray Galactic electrons. Scanning was carried out on two new balloon flight experiments as well as the border area of previous experiments. The identification and evaluation of the energies of the primary electrons were carried out. A new analysis of these data were incorporated into an overall evaluation of the roll of electrons in the problem of the origin of cosmic rays. Recent measurements indicate that the earth may be within the expanding Geminga supernova shock wave which is expected to have a major effect upon the propagation and the energy spectrum of galactic electrons. Calculations with the Geminga model indicate that the cut-off energy may be very close to the observed highest energy electrons in our analysis.

Wilkes, R. Jeffrey

1993-01-01

144

Error analysis of earth physics satellite systems  

NASA Technical Reports Server (NTRS)

Error analysis of distant-satellite-to-close-satellite range-rate, satellite-to-sea altimetry, and ground station to satellite range are made by simulations in which observational variances are assumed, observation equations are formed, and normal equations incremented. The final normal equation matrix is inverted to obtain standard deviations and correlation coefficients. The natural parameters solved for are the broad variations of the gravity field, represented by harmonic coefficients; local variations of gravity, represented by point masses; and the departure of the sea level from the geoid, represented by area means. A standard case of a low (263 km) polar close satellite, three equatorial geosynchronous satellites, and eight ground tracking stations is set up.

Kaula, W. M.

1972-01-01

145

Harmonic Sieve: A Novel Application of Fourier Analysis to Machine Learning Theory and Practice.  

National Technical Information Service (NTIS)

This thesis presents new positive results--both theoretical and empirical--in machine learning. The primary learning-theoretic contribution is the Harmonic Sieve, the first efficient algorithm for learning the well-studied class of Disjunctive Normal Form...

J. C. Jackson

1995-01-01

146

A Harmonic Analysis Method for Unsteady Transonic Flow and Its Application to the Flutter of Airfoils.  

National Technical Information Service (NTIS)

A finite difference method for solving the unsteady transonic flow about harmonically oscillating wings is investigated. The procedure is based on separating the velocity potential into steady and unsteady parts and linearizing the resulting unsteady diff...

F. E. Ehlers W. H. Weatherill

1982-01-01

147

Digital Movement Analysis in Physical Education  

ERIC Educational Resources Information Center

Mobile devices such as smartphones and tablets offer applications (apps) that make digital movement analysis simple and efficient in physical education. Highly sophisticated movement analysis software has been available for many years but has mainly appealed to coaches of elite athletes and biomechanists. Apps on mobile devices are less expensive…

Trout, Josh

2013-01-01

148

Multiscale analysis of polarization-resolved third-harmonic generation microscopy from ordered lipid assemblies  

NASA Astrophysics Data System (ADS)

Nonlinear optical microscopy is a biocompatible avenue for probing ordered molecular assemblies in biological tissues. As in linear optics, the nonlinear optical response from ordered systems is polarization-sensitive. This dependence can be used to identify and characterize local molecular ordering with micrometer-scale 3D resolution in a nonlinear microscope. In particular, third-harmonic generation (THG) microscopy is a nonlinear optical modality sensitive to the electronic nonlinear susceptibility ?(3) of a material. THG microscopy can be used to map ?(3) spatial variations (i.e. material interfaces), and to probe birefringence. In principle, polarization-resolved THG (P-THG) can therefore be used to probe ordered molecular arrays. However, the orientation, distribution, and nonlinear optical properties of the molecules near the beam focus all affect the detected signal. It is therefore necessary to develop a theoretical method which decouples these effects and permits the extraction of orientational information from P-THG images. In this report, we first present P-THG images of model systems (lipid droplets, multilamellar lipid vesicles) and biological tissues (human skin biopsy) which establish that P-THG is sensitive to lipid ordering and that it is maximized when excitation polarization is parallel to the ordered lipid molecules, giving impetus for the development of a thorough theoretical analysis. We then outline a multiscale model spanning the molecular (nm) and ensemble (?m) scales predicting the PTHG signal, consisting of three main steps: (i) calculation of the molecular electronic hyperpolarizability; (ii) determination of the anisotropic ?(3) for various molecular distribution parameters; and (iii) numerical calculations of the P-THG signal from lipid-water interfaces. This analysis links the measured P-THG response to lipid molecular structure and ordering.

Zimmerley, Maxwell; Mahou, Pierre; Débarre, Delphine; Schanne-Klein, Marie-Claire; Beaurepaire, Emmanuel

2013-03-01

149

Spherical cap harmonic analysis of Super Dual Auroral Radar Network (SuperDARN) observations for generating maps of ionospheric convection  

Microsoft Academic Search

A spherical cap harmonic analysis (SCHA) technique is introduced for mapping the 2-D high-latitude ionospheric convection pattern based on Super Dual Auroral Radar Network (SuperDARN) velocity measurements. The current method for generating such maps is the FIT technique which generates global-scale maps over the entire convection region. This is accomplished by combining observations with a statistical model to prevent unphysical

R. A. D. Fiori; D. H. Boteler; A. V. Koustov; G. V. Haines; J. M. Ruohoniemi

2010-01-01

150

General coupled-mode analysis of Cerenkov-radiation-type second-harmonic generation in channel and fiber waveguides  

Microsoft Academic Search

Coupled-mode analysis of Cerenkov-radiation-type second-harmonic generation, using channel and fiber waveguides, is presented from the viewpoint of device design. Nonlinear coupled-mode equations generally applicable for various waveguide configurations are derived and solved by considering the effects of pump-power depletion, waveguide loss, and effects of nonlinear gratings. Analytical expressions for the conversion efficiency as well as the near- and far-field radiation

Toshiaki Suhara; Takashi Morimoto; Hiroshi Nishihara

1993-01-01

151

Blind Analysis in Nuclear and Particle Physics  

NASA Astrophysics Data System (ADS)

During the past decade, blind analysis has become a widely used tool in nuclear and particle physics measurements. A blind analysis avoids the possibility of experimenters biasing their result toward their own preconceptions by preventing them from knowing the answer until the analysis is complete. There is at least circumstantial evidence that such a bias has affected past measurements, and as experiments have become costlier and more difficult and hence harder to reproduce, the possibility of bias has become a more important issue than in the past. We describe here the motivations for performing a blind analysis, and give several modern examples of successful blind analysis strategies.

Klein, Joshua R.; Roodman, Aaron

2005-12-01

152

Ion cyclotron harmonics in auroral radar echoes: Real effect or analysis artifact  

SciTech Connect

Certain analyses of Canadian radar studies of auroral electrojet echoes have apparently shown spectra with multiple ion cyclotron harmonic peaks. On the basis of these, it has been argued that ion cyclotron effects must be important for all echo types seen by VHF radars, not just type 3. The authors reject this conclusion for two reasons: (1) at the altitude of auroral backscatter ({approximately} 100-120 km) the ion-neutral collision frequency is much higher than the gyro frequency - ions are essentially unmagnetized; (2) they show that the high resolution signal processing algorithm employed does not distinguish between echoes with and without harmonic structure. With a simulation, they show that the algorithm itself can impose apparent quasi harmonic structure onto the spectrum of random noise.

Farley, D.T.; Sahr, J.D. (Cornell Univ., Ithaca, NY (USA)); Providakes, J.F. (MITRE Corp., McLean, VA (USA))

1991-04-01

153

Structural analysis of blended materials using multiphoton autofluorescence and second harmonic generation microscopy  

NASA Astrophysics Data System (ADS)

The purpose of this work is to investigate the microstructure of blended materials using non-invasive, optical imaging modality. Multiphoton autofluorescence and second harmonic generation signals will be used for characterizing and quantifying individual non-linear optical properties of each polymer in pure polymeric thin films. In addition, reflected confocal signals will used to outline the interface of refractive index mismatch. And the phase separation phenomenon of immiscible blended membranes composed of different ratio of nylon and chitosan are analyzed and differentiated using the non-invasive optical information including autofluerescence, second harmonic generation, and reflected signals. We therefore propose the potentiality of using multiphoton autofluorescence and second harmonic generation microscopy complemented with reflected confocal microscopy for studying the synthetic blended polymeric scaffolds and also, in the future, the dynamic, in vivo, cell-matrix interaction in the field of tissue engineering.

Tan, Hsin-Yuan; Lin, Ming-Guo; Lin, Sung-Jan; Hsiao, Wen-Chu; Wen, Liang-Kung; Chen, Wei-Liang; Young, Tai-Horng; Dong, Chen-Yuan

2007-03-01

154

High-order harmonic generation from polyatomic molecules including nuclear motion and a nuclear modes analysis  

SciTech Connect

We present a generic approach for treating the effect of nuclear motion in high-order harmonic generation from polyatomic molecules. Our procedure relies on a separation of nuclear and electron dynamics where we account for the electronic part using the Lewenstein model and nuclear motion enters as a nuclear correlation function. We express the nuclear correlation function in terms of Franck-Condon factors, which allows us to decompose nuclear motion into modes and identify the modes that are dominant in the high-order harmonic generation process. We show results for the isotopes CH{sub 4} and CD{sub 4} and thereby provide direct theoretical support for a recent experiment [S. Baker et al., Science 312, 424 (2006)] that uses high-order harmonic generation to probe the ultrafast structural nuclear rearrangement of ionized methane.

Madsen, C. B.; Abu-samha, M.; Madsen, L. B. [Lundbeck Foundation Theoretical Center for Quantum System Research, Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark)

2010-04-15

155

Dynamic Analysis of Wind Turbine Planetary Gears Using an Extended Harmonic Balance Approach: Preprint  

SciTech Connect

The dynamics of wind turbine planetary gears with gravity effects are investigated using an extended harmonic balance method that extends established harmonic balance formulations to include simultaneous internal and external excitations. The extended harmonic balance method with arc-length continuation and Floquet theory is applied to a lumped-parameter planetary gear model including gravity, fluctuating mesh stiffness, bearing clearance, and nonlinear tooth contact to obtain the planetary gear dynamic response. The calculated responses compare well with time domain integrated mathematical models and experimental results. Gravity is a fundamental vibration source in wind turbine planetary gears and plays an important role in system dynamics, causing hardening effects induced by tooth wedging and bearing-raceway contacts. Bearing clearance significantly reduces the lowest resonant frequencies of translational modes. Gravity and bearing clearance together lowers the speed at which tooth wedging occurs lower than the resonant frequency.

Guo, Y.; Keller, J.; Parker, R. G.

2012-06-01

156

A statistical basis for harmonization of thyroid stimulating hormone immunoassays using a robust factor analysis model.  

PubMed

Abstract Background: Between-method equivalence ideally is achieved by calibration against an SI-traceable reference measurement procedure. For measurement of thyroid stimulating hormone (TSH), it is unlikely to accomplish this goal in mid-term. Therefore, we investigated a statistical alternative based on a factor analysis (FA) model. Methods: The FA model was applied to TSH results for 94 samples generated by 14 immunoassays (concentration range: 0.0005-78 mIU/L). The dataset did not fulfill the assumption of a homogeneous sample from an elliptically symmetric distribution, and, therefore, required standardization prior to application of the FA model. As outliers and missing values also occurred, the key quantities of the FA model had to be estimated with a method that can handle these complications. We selected a robust alternating regressions (RAR) method, which replaces in the minimization criterion of the fitting process the squared differences between results xij and model fit x^ij ${\\hat x_{ij}}$ by a weighted absolute difference. The weights are adaptively determined in successive regressions, which down weighs the outliers. The weights for missing values are set to zero. Results: The quality of the estimated targets was reflected by their central position in the distributions, and description of the relationship between results and targets by a simple two-parameter regression equation with high correlation coefficients and low SDs of the percentage-residuals. Mathematical recalibration eliminated the method differences and improved the between-method CV from 11% to 6%. Conclusions: RAR applied to a multimethod comparison dataset hampered by outliers and missing values, is fit to the purpose of harmonization. PMID:24566365

Stöckl, Dietmar; Van Uytfanghe, Katleen; Van Aelst, Stefan; Thienpont, Linda M

2014-07-01

157

Spherical cap harmonic analysis of the Arctic ionospheric TEC for one solar cycle  

NASA Astrophysics Data System (ADS)

knowledge of the Arctic ionosphere total electron content (TEC) and its variations has scientific relevance due to the unique characteristics of the polar ionosphere. Understanding the Arctic TEC is also important for precise positioning and navigation in the Arctic. This study utilized the spherical cap harmonic analysis (SCHA) method to map the Arctic TEC for the most recent solar cycle from 2000 to 2013 and analyzed the distributions and variations of the Arctic TEC at different temporal and spatial scales. Even with different ionosphere conditions during the solar cycle, the results showed that the existing International Global Navigation Satellite Systems Service stations are sufficient for mapping the Arctic TEC. The SCHA method provides adequate accuracy and resolution to analyze the spatiotemporal distributions and variations of the Arctic TEC under different ionosphere conditions and to track ionization patches in this polar region (e.g., the ionization event of 26 September 2011). The results derived from the SCHA model were compared to direct observations using the Super Dual Auroral Radar Network radar. The SCHA method is able to predict the TEC in the long and short terms. This paper presented a long-term prediction with a relative uncertainty of 75% for a latency of one solar cycle and a short-term prediction with errors of ±2.2 total electron content units (TECUs, 1 TECU = 1016 el m-2), ±3.8 TECU, and ±4.8 TECU for a latency of 1, 2, and 3 days, respectively. The SCHA is an effective method for mapping, predicting, and analyzing the Arctic TEC.

Liu, Jingbin; Chen, Ruizhi; An, Jiachun; Wang, Zemin; Hyyppa, Juha

2014-01-01

158

Multielectron Correlation in High-Harmonic Generation: A 2D Model Analysis  

SciTech Connect

We analyze the role of multielectron dynamics in high-harmonic generation spectroscopy, using an example of a two-electron system. We identify and systematically quantify the importance of correlation and exchange effects. One of the main sources for correlation is identified to be the polarization of the ion by the recombining continuum electron. This effect, which plays an important qualitative and quantitative role, seriously undermines the validity of the standard approaches to high-harmonic generation, which ignore the contribution of excited ionic states to the radiative recombination of the continuum electron.

Sukiasyan, Suren [Physics Department and Center for Research in Photonics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario K1N 6N5 (Canada); National Research Council, 100 Sussex Drive, Ottawa, Ontario K1A 0R6 (Canada); McDonald, Chris; Destefani, Carlos; Brabec, Thomas [Physics Department and Center for Research in Photonics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario K1N 6N5 (Canada); Ivanov, Misha Yu. [National Research Council, 100 Sussex Drive, Ottawa, Ontario K1A 0R6 (Canada)

2009-06-05

159

Symbolic Vector Analysis in Plasma Physics  

SciTech Connect

Many problems in plasma physics involve substantial amounts of analytical vector calculation. The complexity usually originates from both the vector operations themselves and the choice of underlying coordinate system. A computer algebra package for symbolic vector analysis in general coordinate systems, General Vector Analysis (GVA), is developed using Mathematica. The modern viewpoint for 3D vector calculus, differential forms on 3-manifolds, is adopted to unify and systematize the vector calculus operations in general coordinate systems. This package will benefit physicists and applied mathematicians in their research where complicated vector analysis is required. It will not only save a huge amount of human brain-power and dramatically improve accuracy, but this package will also be an intelligent tool to assist researchers in finding the right approaches to their problems. Several applications of this symbolic vector analysis package to plasma physics are also given.

Qin, H.; Tang, W.M.; Rewoldt, G.

1997-10-09

160

Harmonic Golay coded excitation based on harmonic quadrature demodulation method.  

PubMed

Harmonic coded excitation techniques have been used to increase SNR of harmonic imaging with limited peak voltage. Harmonic Golay coded excitation, in particular, generates each scan line using four transmit-receive cycles, unlike conventional Golay coded excitation method, thus resulting in low frame rates. In this paper we propose a method of increasing the frame rate of said method without impacting the image quality. The proposed method performs two transmit-receive cycles using QPSK code to ensure that the harmonic components of incoming signals are Golay coded and uses harmonic quadrature demodulation to extract compressed second harmonic component only. The proposed method has been validated through mathematical analysis and MATLAB simulation, and has been verified to yield a limited error of -52.08dB compared to the ideal case. Therefore, the proposed method doubles the frame rate compared to the existing harmonic Golay coded excitation method without significantly deteriorating the image quality. PMID:19164018

Kim, Sang-Min; Song, Jae-Hee; Song, Tai-Kyong

2008-01-01

161

24 CFR 401.451 - PAE Physical Condition Analysis (PCA).  

...2014-04-01 2014-04-01 false PAE Physical Condition Analysis (PCA). 401...Restructuring Plan § 401.451 PAE Physical Condition Analysis (PCA). (a...The PAE must independently evaluate the physical condition of the project by...

2014-04-01

162

Harmonic analysis and performance improvement of slip energy recovery induction motor drives  

Microsoft Academic Search

Slip energy recovery induction motor drives are used in high power applications, in which by controlling the slip power a variable speed drive system is provided. However, poor power factor is a disadvantage of the system. Presence of sub-harmonics of the line frequency on the stator side is one of the special features of these drives. A phase-controlled inverter can

Jawad Faiz; H. Barati; Eyup Akpinar

2001-01-01

163

Performance analysis of Z - source Inverter based ASD system with reduced harmonics  

Microsoft Academic Search

This paper presents the Z - source inverter for adjustable speed drive system. The Z - source inverter employs a unique impedance network couple with inverter main circuit. By controlling the shoot through duty cycle, the Z - source inverter system using MOSFETS provide ride - through capability during voltage sags, reduces line harmonics, improves power factor and high reliability,

Amitava Das; S. P. Chowdhury; A. Domijan

2008-01-01

164

Ion cyclotron harmonics in auroral radar echoes: Real effect or analysis artifact?  

Microsoft Academic Search

Certain analyses of Canadian radar studies of auroral electrojet echoes have apparently shown spectra with multiple ion cyclotron harmonic peaks. On the basis of these, it has been argued that ion cyclotron effects must be important for all echo types seen by VHF radars, not just type 3. We reject this conclusion for two reasons: (1) at the altitude of

D. T. Farley; J. D. Sahr; J. F. Providakes

1991-01-01

165

Ion cyclotron harmonics in auroral radar echoes - Real effect or analysis artifact?  

Microsoft Academic Search

Certain analyses of Canadian radar studies of auroral electrojet echoes have apparently shown spectra with multiple ion cyclotron harmonic peaks. On the basis of these, it has been argued that ion cyclotron effects must be important for all echo types seen by VHF radars, not just type 3. This conclusion is rejected for two reasons: (1) at the altitude of

D. T. Farley; J. D. Sahr; J. F. Providakes

1991-01-01

166

Ion cyclotron harmonics in auroral radar echoes: Real effect or analysis artifact  

Microsoft Academic Search

Certain analyses of Canadian radar studies of auroral electrojet echoes have apparently shown spectra with multiple ion cyclotron harmonic peaks. On the basis of these, it has been argued that ion cyclotron effects must be important for all echo types seen by VHF radars, not just type 3. The authors reject this conclusion for two reasons: (1) at the altitude

D.T. Farley; J. D. Sahr; J. F. Providakes

1991-01-01

167

A fault analysis of DC electric arc furnaces with SVC harmonic filters in a minimill plant  

Microsoft Academic Search

This paper proposes the most feasible solution to overcome the failure of the 2nd harmonic filter in the static VAR compensator (SVC) which operates with the DC electric arc furnace (EAF) at Gwangyang Steel Mill in Korea. In order to investigate the causes of this failure, various measurements were carried out on the DC EAF and the main transformer at

Hansang Lee; Gilsoo Jang; Byungmoon Han

2010-01-01

168

An integral equation analysis of the harmonic response of three-layer beams  

Microsoft Academic Search

The integral equations of harmonic motion have been derived and solved for three-layer sandwich beams with a constrained linear viscoelastic core. The method of solution required first the construction of the Green's vector for a beam in analytical form. Following this, the integral equations were derived and readily approximated by matrix equations which were finally solved numerically. In addition to

E. Ioannides; P. Grootenhuis

1982-01-01

169

Harmonic measurements, analysis, and power factor correction in a modern steel manufacturing facility  

Microsoft Academic Search

Maximizing electric power transfer directly affects the productivity of an electric arc furnace operation. Arc furnaces and rolling mill loads operate at power factors that result in penalty charges and lower bus voltages. In addition, the nonlinear characteristics of the furnace arcs and rolling mill drives generate significant harmonic currents that flow through the plant and utility power system. These

Douglas Andrews; Martin T. Bishop; John F. Witte

1996-01-01

170

On the Method of Harmonic Analysis of Weak Tides (O Metode Garmonicheskogo Analiza Slabykh Prilivov).  

National Technical Information Service (NTIS)

The author considers the effect of perturbing waves and the zero point motion on the harmonic constants of determined tidal waves obtained on processing an annual series by the method of weak tides. It is shown that the processing of observations of tide ...

V. G. Balenko

1969-01-01

171

Dealing with periodical loads and harmonics in operational modal analysis using time-varying transmissibility functions  

NASA Astrophysics Data System (ADS)

Periodical loads, such as waves and rotating machinery, form a problem for operational modal analysis (OMA). In OMA only the vibrations of a structure of interest are measured and little to nothing is known about the loads causing these vibrations. Therefore, it is often assumed that all dynamics in the measured data are linked to the system of interest. Periodical loads defy this assumption as their periodical behavior is often visible within the measured vibrations. As a consequence most OMA techniques falsely associate the dynamics of the periodical load with the system of interest. Without additional information about the load, one is not able to correctly differentiate between structural dynamics and the dynamics of the load. In several applications, e.g. turbines and helicopters, it was observed that because of periodical loads one was unable to correctly identify one or multiple modes. Transmissibility based OMA (TOMA) is a completely different approach to OMA. By using transmissibility functions to estimate the structural dynamics of the system of interest, all influence of the load-spectrum can be eliminated. TOMA therefore allows to identify the modal parameters without being influenced by the presence of periodical loads, such as harmonics. One of the difficulties of TOMA is that the analyst is required to find two independent datasets, each associated with a different loading condition of the system of interest. This poses a dilemma for TOMA; how can an analyst identify two different loading conditions when little is known about the loads on the system? This paper tackles that problem by assuming that the loading conditions vary continuously over time, e.g. the changing wind directions. From this assumption TOMA is developed into a time-varying framework. This development allows TOMA to not only cope with the continuously changing loading conditions. The time-varying framework also enables the identification of the modal parameters from a single dataset. Moreover, the time-varying TOMA approach can be implemented in such a way that the analyst no longer has to identify different loading conditions. For these combined reasons the time-varying TOMA is less dependent on the user and requires less testing time than the earlier TOMA-technique.

Weijtjens, Wout; Lataire, John; Devriendt, Christof; Guillaume, Patrick

2014-12-01

172

Harmonic elimination of electric arc furnaces by active power filters and their stability analysis  

Microsoft Academic Search

Three different active power filter (APF) configurations are developed for harmonic elimination of a three-phase electric arc furnace (EAF). Three single-phase APF, a three-wire APF and a four-wire APF are developed for this purpose. A predictive control method of the APFs based on dynamic programming method is applied and the results of the simulation studies are compared. Finally the stability

H. Ghoudjehbaklou; A. Kargar

2002-01-01

173

3D quantitative Fourier analysis of second harmonic generation microscopy images of collagen structure in cartilage  

NASA Astrophysics Data System (ADS)

One of the main advantages of nonlinear microscopy is that it provides 3D imaging capability. Second harmonic generation is widely used to image the 3D structure of collagen fibers, and several works have highlighted the modification of the collagen fiber fabric in important diseases. By using an ellipsoidal specific fitting technique on the Fourier transformed image, we show, using both synthetic images and SHG images from cartilage, that the 3D direction of the collagen fibers can be robustly determined.

Romijn, Elisabeth I.; Lilledahl, Magnus B.

2013-02-01

174

Nonlinear analysis of high-harmonic slotted gyro-TWT amplifier  

Microsoft Academic Search

A nonlinear self-consistent simulation code is employed to investigate the behavior of the slotted gyrotron traveling-wave amplifier (gyro-TWT), in which an axis-encircling electron beam synchronously interacts with a high-order azimuthal mode in a magnetron-type waveguide. The efficiency of a fourth-harmonic device with an ideal 60 kV, 5 A beam is shown to reach 30% for ????\\/?z=2. The growth rate for

C. K. Chong; D. B. McDermott; A. J. Balkcum

1992-01-01

175

ATOMIC AND MOLECULAR PHYSICS: Investigation of analytical potential energy function, harmonic frequency and vibrational levels for the X2?+ and A2 states of CN radical  

NASA Astrophysics Data System (ADS)

This paper calculates the equilibrium structure and the potential energy functions of the ground state (X2?+) and the low lying excited electronic state (A2II) of CN radical are calculated by using CASSCF method. The potential energy curves are obtained by a least square fitting to the modified Murrell-Sorbie function. On the basis of physical theory of potential energy function, harmonic frequency (?e) and other spectroscopic constants (?e?e, ?e and ?e) are calculated by employing the Rydberg-Klein-Rees method. The theoretical calculation results are in excellent agreement with the experimental and other complicated theoretical calculation data. In addition, the eigenvalues of vibrational levels have been calculated by solving the radial one-dimensional Schrödinger equation of nuclear motion using the algebraic method based on the analytical potential energy function.

Wang, Jian-Kun; Wu, Zhen-Sen

2008-08-01

176

Harmonic analysis of tides and tidal currents in South San Francisco Bay, California  

USGS Publications Warehouse

Water level observations from tide stations and current observations from current-meter moorings in South San Francisco Bay (South Bay), California have been harmonically analysed. At each tide station, 13 harmonic constituents have been computed by a least-squares regression without inference. Tides in South Bay are typically mixed; there is a phase lag of approximately 1 h and an amplification of 1??5 from north to south for a mean semi-diurnal tide. Because most of the current-meter records are between 14 and 29 days, only the five most important harmonics have been solved for east-west and north-south velocity components. The eccentricity of tidal-current ellipse is generally very small, which indicates that the tidal current in South Bay is strongly bidirectional. The analyses further show that the principal direction and the magnitude of tidal current are well correlated with the basin bathymetry. Patterns of Eulerian residual circulation deduced from the current-meter data show an anticlockwise gyre to the west and a clockwise gyre to the east of the main channel in the summer months due to the prevailing westerly wind. Opposite trends have been observed during winter when the wind was variable. ?? 1985.

Cheng, R. T.; Gartner, J. W.

1985-01-01

177

Operational modal analysis of a ship model in the presence of harmonic excitation  

NASA Astrophysics Data System (ADS)

A ship is operated under an extremely complex environment, and waves and winds are assumed to be the stochastic excitations. Moreover, the propeller, host and mechanical equipment can also induce the harmonic responses. In order to reduce structural vibration, it is important to obtain the modal parameters information of a ship. However, the traditional modal parameter identification methods are not suitable since the excitation information is difficult to obtain. Natural excitation technique-eigensystem realization algorithm (NExT-ERA) is an operational modal identification method which abstracts modal parameters only from the response signals, and it is based on the assumption that the input to the structure is pure white noise. Hence, it is necessary to study the influence of harmonic excitations while applying the NExT-ERA method to a ship structure. The results of this research paper indicate the practical experiences under ambient excitation, ship model experiments were successfully done in the modal parameters identification only when the harmonic frequencies were not too close to the modal frequencies.

Xu, Junchen; Hong, Ming; Liu, Xiaobing

2013-03-01

178

Visual physics analysis - from desktop to physics analysis at your fingertips  

NASA Astrophysics Data System (ADS)

Visual Physics Analysis (VISPA) is an analysis environment with applications in high energy and astroparticle physics. Based on a data-flow-driven paradigm, it allows users to combine graphical steering with self-written C++ and Python modules. This contribution presents new concepts integrated in VISPA: layers, convenient analysis execution, and web-based physics analysis. While the convenient execution offers full flexibility to vary settings for the execution phase of an analysis, layers allow to create different views of the analysis already during its design phase. Thus, one application of layers is to define different stages of an analysis (e.g. event selection and statistical analysis). However, there are other use cases such as to independently optimize settings for different types of input data in order to guide all data through the same analysis flow. The new execution feature makes job submission to local clusters as well as the LHC Computing Grid possible directly from VISPA. Web-based physics analysis is realized in the VISPA@Web project, which represents a whole new way to design and execute analyses via a standard web browser.

Bretz, H.-P.; Erdmann, M.; Fischer, R.; Hinzmann, A.; Klingebiel, D.; Komm, M.; Lingemann, J.; Rieger, M.; Müller, G.; Steggemann, J.; Winchen, T.

2012-06-01

179

Application of spherical cap harmonic analysis to plasma convection mapping at high latitudes  

NASA Astrophysics Data System (ADS)

The primary goal of this work is to develop, validate, and apply a new technique for mapping the high-latitude ionospheric plasma flow (convection pattern) from velocity measurements routinely performed by the Super Dual Auroral Radar (SuperDARN) network of high frequency (HF) radars. The currently employed FIT technique relies heavily on assumptions that are not always justifiable. A spherical cap harmonic analysis (SCHA) technique, traditionally used in handling geomagnetic field data, is introduced for mapping the high-latitude ionospheric convection pattern based on SuperDARN velocity measurements. The SCHA technique does not require contributions from a statistical model which is dependent on the magnitude and orientation of the interplanetary magnetic field (IMF), and does not confine the high-latitude flows to a specific region based on magnetic latitude. Several steps are taken to validate the SCHA convection mapping technique. First, it is demonstrated that the SCHA technique can reproduce an arbitrary pattern based on simulated data modified by a random noise component. SCHA maps of the global scale plasma flow pattern for various IMF conditions are next shown to be consistent with expectations for patterns reported in the literature. SCHA maps are compared to ion drifts measured by the Defense Meteorological Satellite Program (DMSP) satellites and with convection vectors inferred by merging SuperDARN measurements at beam crossings. The SCHA technique is shown to perform comparably to the FIT technique over regions of good data coverage. The SCHA technique provides a better representation of the ionospheric convection pattern for regions with limited data coverage and over regions of highly variable flow, particularly near the equatorward edge of the mapping region. SCHA analysis of SuperDARN data to create convection maps is expanded to include magnetometer measurements of the perturbation magnetic field. Plasma flow is determined from magnetometer data by combining the equivalent current determined from the external component of the perturbation magnetic field with a model of the ionospheric conductivity. The SCHA technique is used to investigate the reconfiguration of the convection pattern and changes to the cross polar-cap potential (CPCP) associated with a sudden transition in the vertical component of the IMF from stable positive to stable negative values. For such events, the FIT technique might misrepresent the convection pattern if the fitting is dominated by the a-priori statistical convection model. Both magnetometer and SuperDARN data sets are examined. The IMF transition wavefront impinges upon the magnetosphere near the 10 MLT sector; perturbations are clearly seen on the dayside with a ˜10 minute delay on the nightside. This translates into a dayside-to-nightside progression of the ionospheric response observed in the magnetic perturbations and SuperDARN velocities, contrary to what was reported for a number of other events in the literature. The foci of the new dawn and duskside convection cells are shown to steadily shift toward the dayside (over a period of 10-12 minutes, beginning 4-6 minutes after the onset of the ionospheric response) and do not 'snap' to their final position. Once the convection foci reach a final location, the overall convection pattern enhances for a period of ˜25 minutes. These results support the idea that the ionospheric convection response to a southward turning of the IMF is a two-stage process; (1) an initial dayside-to-nightside progression of the observed ionospheric response and a reconfiguration of the convection pattern, and (2) the subsequent intensification of the convection pattern. An additional investigation is performed to determine whether the polar cap north (PCN) magnetic index is satisfactory for estimating the CPCP and average cross polar cap flow velocity (CPCV). A roughly linear increase of both the CPCP and CPCV with PCN is found for 0 ? PCN ? 4, with a tendency for saturation for PCN > 4. The CPCP calculated using the SCHA-technique i

Fiori, Robyn A. D.

180

Gender and Physics: a Theoretical Analysis  

NASA Astrophysics Data System (ADS)

This article argues that the objections raised by Koertge (1998), Gross and Levitt (1994), and Weinberg (1996) against feminist scholarship on gender and physics are unwarranted. The objections are that feminist science studies perpetuate gender stereotypes, are irrelevant to the content of physics, or promote epistemic relativism. In the first part of this article I argue that the concept of gender, as it has been developed in feminist theory, is a key to understanding why the first objection is misguided. Instead of reinforcing gender stereotypes, feminist science studies scholars can formulate empirically testable hypotheses regarding local and contested beliefs about gender. In the second part of this article I argue that a social analysis of scientific knowledge is a key to understanding why the second and the third objections are misguided. The concept of gender is relevant for understanding the social practice of physics, and the social practice of physics can be of epistemic importance. Instead of advancing epistemic relativism, feminist science studies scholars can make important contributions to a subfield of philosophy called social epistemology.

Rolin, Kristina

181

BESIU Physical Analysis on Hadoop Platform  

NASA Astrophysics Data System (ADS)

In the past 20 years, computing cluster has been widely used for High Energy Physics data processing. The jobs running on the traditional cluster with a Data-to-Computing structure, have to read large volumes of data via the network to the computing nodes for analysis, thereby making the I/O latency become a bottleneck of the whole system. The new distributed computing technology based on the MapReduce programming model has many advantages, such as high concurrency, high scalability and high fault tolerance, and it can benefit us in dealing with Big Data. This paper brings the idea of using MapReduce model to do BESIII physical analysis, and presents a new data analysis system structure based on Hadoop platform, which not only greatly improve the efficiency of data analysis, but also reduces the cost of system building. Moreover, this paper establishes an event pre-selection system based on the event level metadata(TAGs) database to optimize the data analyzing procedure.

Huo, Jing; Zang, Dongsong; Lei, Xiaofeng; Li, Qiang; Sun, Gongxing

2014-06-01

182

Physics research in Israel—A preliminary bibliometric analysis  

Microsoft Academic Search

The impact of physics research carried out in Israel on the international literature is assessed from data on publication and citation counts. We have considered in this analysis all papers published from Israel and covered under six of the ten major sections of INSPEC's Physics Abstracts, January-June 1977 (covering condensed matter physics, nuclear and particle physics, atomic and molecular physics

Subbiah Arunachalam; M. K. Dhirendra Rao; Praveen K. Shrivastava

1984-01-01

183

Autoregressive harmonic analysis of the earth's polar motion using homogeneous International Latitude Service data  

NASA Technical Reports Server (NTRS)

The homogeneous set of 80-year-long (1900-1979) International Latitude Service (ILS) polar motion data is analyzed using the autoregressive method (Chao and Gilbert, 1980), which resolves and produces estimates for the complex frequency (or frequency and Q) and complex amplitude (or amplitude and phase) of each harmonic component in the data. The ILS data support the multiple-component hypothesis of the Chandler wobble. It is found that the Chandler wobble can be adequately modeled as a linear combination of four (coherent) harmonic components, each of which represents a steady, nearly circular, prograde motion. The four-component Chandler wobble model 'explains' the apparent phase reversal during 1920-1940 and the pre-1950 empirical period-amplitude relation. The annual wobble is shown to be rather stationary over the years both in amplitude and in phase, and no evidence is found to support the large variations reported by earlier investigations. The Markowitz wobble is found to be marginally retrograde and appears to have a complicated behavior which cannot be resolved because of the shortness of the data set.

Chao, B. F.

1983-01-01

184

Stability Analysis of a Second Harmonic Coaxial-Waveguide Gyrotron Backward-Wave Oscillator  

NASA Astrophysics Data System (ADS)

This study analyzes the stability of a Ka-band second harmonic gyrotron backward-wave oscillator (gyro-BWO) with a coaxial interaction waveguide. All of the possible competing modes in the frequency tuning range are considered. To suppress various competing modes, the downstream part of the coaxial interaction waveguide is loaded with distributed losses. Although the competing modes have different kinds of transverse field distributions, simulation results show that the losses of the outer cylinder and those of the inner cylinder serve as complementary means of suppressing the competing modes. The losses can stabilize the competing modes while having minor effects on the start-oscillation current of the operating mode. Detailed investigations were performed involving the dependence of the start-oscillation currents on the parameters of the lossy inner cylinder and the lossy outer cylinder, including the resistivity and the length of the lossy section. Moreover, under stable operating conditions, the performances of the second harmonic coaxial gyro-BWO with different sets of circuit parameters are predicted and compared.

Hung, C. L.; Hong, J. H.

2012-12-01

185

Quantitative analysis of diseased horse tendons using Fourier-transform-second-harmonic generation imaging  

NASA Astrophysics Data System (ADS)

Fourier transform-second-harmonic generation (FT-SHG) imaging is used to quantitatively assess the structural organization of collagen fibers in tendonitis-induced horse tendons. Fiber orientation, isotropy, and the ratio of forward to backward SHG signal (F/B ratio) are used to differentiate the fiber organization between the normal and diseased horse tendons. Each second-harmonic generation (SHG) image is divided into several smaller regions of interest (ROI) and the aforementioned quantitative metrics are calculated across the whole grid. ROIs are further labeled as dark (no or minimal presence of fibers), isotropic (random fiber organization), or anisotropic (regular fiber organization) regions. Results show that the normal tendon possesses minimal isotropic regions and small standard deviations in the histograms of orientation and F/B ratio, indicating an intact and highly regular fiber organization. However, the tendonitis-induced horse tendons possess higher number of dark and isotropic regions, and larger standard deviations of the measured parameters, suggesting significantly disoriented and disorganized collagen fibers. This type of quantification would be highly beneficial in diagnosing and determining the stage of tendonitis in clinical settings. Not limited to tendonitis, the technique could also be applied to other diseases that structurally affect collagen fibers. The advantage of FT-SHG over the conventional polarization microscopy is also discussed.

Sivaguru, Mayandi; Durgam, Sushmitha; Ambekar, Raghu; Luedtke, David; Fried, Glenn; Stewart, Allison; Toussaint, Kimani C., Jr.

2011-02-01

186

Temporal variations in low degree zonal harmonics from Starlette orbit analysis  

SciTech Connect

The dynamical effect of temporal variations in the zonal harmonics of the Earth's gravitational potential due to tidal and meteorological mass redistribution has been observed using satellite laser ranging (SLR) measurements to Starlette. The secular variations in the Earth's zonal harmonics, J{sub t}, and the year-to-year fluctuation of the even degree annual and semi-annual tides (S{sub a} and S{sub sa}) have been determined from a continuous Starlette orbit spanning from 1983 through 1985. When variations in higher degree zonals are assumed to be zero and the 18.6-year is fixed to an equilibrium value, the results are: J{sub 2} = ({minus}2.5 {plus minus} 0.3), J{sub 3} = ({minus}0.1 {plus minus} 0.3), J{sub 4} = (0.3 {plus minus} 0.6), in units of 10{sup {minus}11}yr{sup {minus}1}. The Starlette-derived J{sub 2} is in good agreement with the value observed from Lageos and values predicted from postglacial rebound. The mean values for S{sub a} and S{sub sa} tides are in good agreement with other tide solutions. The year-to-year fluctuations of the even degree S{sub a}, deduced from Starlette node variations, are about 25% of the mean value obtained during the three-year Starlette orbit span.

Cheng, M.K.; Eanes, R.J.; Shum, C.K.; Schutz, B.E.; Tapley, B.D. (Univ. of Texas, Austin (USA))

1989-05-01

187

Theoretical analysis of dynamic chemical imaging with lasers using high-order harmonic generation  

SciTech Connect

We report theoretical investigations of the tomographic procedure suggested by Itatani et al. [Nature (London) 432, 867 (2004)] for reconstructing highest occupied molecular orbitals (HOMOs) using high-order harmonic generation (HHG). Due to the limited range of harmonics from the plateau region, we found that even under the most favorable assumptions, it is still very difficult to obtain accurate HOMO wave functions using the tomographic procedure, but the symmetry of the HOMOs and the internuclear separation between the atoms can be accurately extracted, especially when lasers of longer wavelengths are used to generate the HHG. Since the tomographic procedure relies on approximating the continuum wave functions in the recombination process by plane waves, the method can no longer be applied upon the improvement of the theory. For future chemical imaging with lasers, we suggest that one may want to focus on how to extract the positions of atoms in molecules instead, by developing an iterative method such that the theoretically calculated macroscopic HHG spectra can best fit the experimental HHG data.

Van-Hoang Le [J. R. Macdonald Laboratory, Department of Physics, Cardwell Hall, Kansas State University, Manhattan, Kansas 66506 (United States); Department of Physics, University of Pedagogy, 280 An Duong Vuong, Ward 5, Ho Chi Minh City (Viet Nam); Anh-Thu Le; Xie Ruihua; Lin, C. D. [J. R. Macdonald Laboratory, Department of Physics, Cardwell Hall, Kansas State University, Manhattan, Kansas 66506 (United States)

2007-07-15

188

International Harmonization of Economic Regulation  

Microsoft Academic Search

With the advancing globalization of the world economy, domestic economic regulations are becoming more and more subject to efforts at international harmonization. This book presents an analysis of this worldwide phenomenon from both a legal and a politico-economic perspective by focusing on (1) the backgrounds and objectives of international harmonization, (2) the negotiating processes involved, and (3) the impact of

Junji Nakagawa

189

Physical optics analysis of HARP-B  

NASA Astrophysics Data System (ADS)

We present a physical optics analysis of the Heterodyne Array Receiver Program B-band (HARP-B) receiver for the James Clerk Maxwell Telescope (JCMT). Three sets of calculations are performed: 1. A Gaussian beam analysis to determine grid sizes for the Mach-Zehnder polarising interferometer. It is shown that an optimum grid size of 150mm clear diameter has little effect on the beam pattern and transmission of power through the system. 2. A Model of the HARP-B Imaging array is created using an ideal beam pattern for the corrugated feed. This produces an accurate beam pattern of minimal distortion. 3. The throughput and beam patterns for the whole HARP-B system are calculated. This produced beam patterns showing a high degree of symmetry with acceptable power coupling to the reflectors.

Williamson, Ross; Hills, Richard E.; Smith, Harry

2003-02-01

190

In pixel analysis of molecular structure with Stokes vector resolved second harmonic generation microscopy  

NASA Astrophysics Data System (ADS)

We report on measurements and characterization of polarization properties of Second Harmonic (SH) signals using a four-channel photon counting based Stokes polarimeter from type I collagen and starch granules. In this way, the critical polarization parameters including the degree of polarization (DOP), the degree of linear polarization (DOLP), and the degree of circular polarization (DOCP), are extracted from the reconstructed Stokes vector based SH images in a pixel-by-pixel manner. The measurements are further extended to determine the molecular structure and orientation of the samples by varying the polarization states of the incident light and recording the resulting Stokes parameters of the SH signal. The combination of SHG microscopy and Stokes polarimeter hence makes a powerful tool to investigate the structural order of starch granules under water and heating environment.

Mazumder, Nirmal; Xiang, Lu Yun; Qiu, Jianjun; Kao, Fu-Jen

2014-02-01

191

Numerical Analysis of Induced Current in Human Head Exposed to Nonuniform Magnetic Field Including Harmonics  

NASA Astrophysics Data System (ADS)

In this paper, induced currents in an anatomical head model exposed to a non-uniform ELF magnetic field (B-field) including harmonics are numerically calculated, and are discussed based on the basic restriction established by International Commission on Non-Ionizing Radiation Protection (ICNIRP). A casual hair dryer of 100V and 1.2kW is chosen as a typical source of the non-uniform B-field including both the fundamental and second harmonic components. The B-field distribution around the hair dryer is estimated by using the 3-orthogonal magnetic dipole moments, which are derived from a couple of measured values around it. The high-resolution human head model used is constructed based on the MRI images of a real human, and consists of six kinds of tissues (bone, brain, eyeballs, muscle, skin and blood). So-called impedance method is used for the numerical calculation of the induced current. The numerical results show that the maximum values of the induced current of 17µA/m2, for the 60Hz component, which is about 1/120 of the ICNIRP basic restriction appear in the muscle near the eyeball when the hair dryer is used from the side of the head model, and the averaged current in the eyeballs that have the highest conductivity is the highest among the six tissues. It is also demonstrated that the induced current due to the 120Hz B-field becomes comparable to the 60Hz current although the magnitude of the 120Hz B-field is much smaller than that of the 60Hz B-field.

Tarao, Hiroo; Hayashi, Noriyuki; Isaka, Katsuo

192

Harmonic N=2 mechanics  

SciTech Connect

N=2 superconformal many-body quantum mechanics in arbitrary dimensions is governed by a single scalar prepotential which determines the bosonic potential and the boson-fermion couplings. We present a special class of such models, for which the bosonic potential is absent. They are classified by homogeneous harmonic functions subject to physical symmetry requirements, such as translation, rotation and permutation invariance. The central charge is naturally quantized. We provide some examples for systems of identical particles in any dimension.

Galajinsky, Anton [Laboratory of Mathematical Physics, Tomsk Polytechnic University, 634050 Tomsk, Lenin Avenue 30 (Russian Federation); Lechtenfeld, Olaf [Institut fuer Theoretische Physik, Leibniz Universitaet Hannover, Appelstrasse 2, D-30167 Hannover (Germany)

2009-09-15

193

Harmonic engine  

DOEpatents

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. (Livermore, CA)

2009-10-20

194

Design, fabrication, and calibration of a cryogenic search-coil array for harmonic analysis of quadrupole magnets  

SciTech Connect

A cryogenic search-coil array has been fabricated at LBL for harmonic error analysis of SSC model quadrupoles. It consists of three triplets of coils; the center-coil triplet is 10 cm long, and the end coil triplets are 70 cm long. Design objectives are a high bucking ratio for the dipole and quadrupole signals and utility at cryogenic operating currents (approx.6 kA) with sufficient sensitivity for use at room-temperature currents (approx.10 A). the design and fabrication are described. Individual coils are mechanically measured to +-5 ..mu..m, and their magnetic areas measured to 0.05%. A computer program has been developed to predict the quadrupole and dipole bucking ratios from the mechanical and magnetic measurements. The calibration procedure and accuracy of the array are specified. Results of measurements of SSC model quadrupoles are presented. 1 ref., 4 figs.

Green, M.I.; Barale, P.J.; Hassenzahl, W.V.; Nelson, D.H.; O'Neill, J.W.; Schafer, R.V.; Taylor, C.E.

1987-09-01

195

Harmonic analysis approach to the 'TunneLadder' - A modified Karp circuit for millimeter-wave TWTA's  

NASA Technical Reports Server (NTRS)

A field approach to the summed harmonic analysis of the TunneLadder structure, or modified forward-wave Karp circuit, is developed by combining TM(01) and TE(11) modes. Results suggest the suitability of this structure as a high-impedance, about 1-% bandwidth circuit, millimeter-wave forward-wave-type amplifier that is voltage tunable over about a 5-% frequency range and has excellent power handling ability. Theory gives good agreement with experimental results obtained by Karp in omega-beta dispersion and predicts qualitatively the appearances of the antisymmetric mode discussed and of the so called Hightron mode that was discussed earlier in White, Enderby and Birdsall (1964), and Enderby (1964), in addition to the desired symmetric mode.

Kosmahl, H. G.; Palmer, R. W.

1982-01-01

196

The Role of ATPG Fault Diagnostics in Driving Physical Analysis  

Microsoft Academic Search

This paper presents the role that ATPG fault diagnostic tools can play in driving physical device analysis. Barriers exist between the logical fault diagnostic domain and the physical device analysis domain. These barriers are being removed through the application of software tools that use design place-and-route data to bridge the gap between logical and physical domains. A case study in

Roger Nicholson; Cathy Kardach; Bruce Cory

2006-01-01

197

24 CFR 401.451 - PAE Physical Condition Analysis (PCA).  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false PAE Physical Condition Analysis (PCA). 401.451 Section 401... § 401.451 PAE Physical Condition Analysis (PCA). (a) Review and certification...the physical condition of the project by means of a PCA. If the PAE finds any...

2013-04-01

198

Application of functional analysis to perturbation theory of differential equations. [nonlinear perturbation of the harmonic oscillator  

NASA Technical Reports Server (NTRS)

The deviation of the solution of the differential equation y' = f(t, y), y(O) = y sub O from the solution of the perturbed system z' = f(t, z) + g(t, z), z(O) = z sub O was investigated for the case where f and g are continuous functions on I x R sup n into R sup n, where I = (o, a) or I = (o, infinity). These functions are assumed to satisfy the Lipschitz condition in the variable z. The space Lip(I) of all such functions with suitable norms forms a Banach space. By introducing a suitable norm in the space of continuous functions C(I), introducing the problem can be reduced to an equivalent problem in terminology of operators in such spaces. A theorem on existence and uniqueness of the solution is presented by means of Banach space technique. Norm estimates on the rate of growth of such solutions are found. As a consequence, estimates of deviation of a solution due to perturbation are obtained. Continuity of the solution on the initial data and on the perturbation is established. A nonlinear perturbation of the harmonic oscillator is considered a perturbation of equations of the restricted three body problem linearized at libration point.

Bogdan, V. M.; Bond, V. B.

1980-01-01

199

Harmonic analysis of irradiation asymmetry for cylindrical implosions driven by high-frequency rotating ion beams.  

PubMed

Cylindrical implosions driven by intense heavy ion beams should be instrumental in the near future for study of high-energy-density matter. By rotating the beam by means of a high-frequency wobbler, it should be possible to deposit energy in the outer layers of a cylinder, compressing the material deposited in its core. The beam's temporal profile should, however, generate an inevitable irradiation asymmetry likely to feed the Rayleigh-Taylor instability (RTI) during the implosion phase. In this paper, we compute the Fourier components of the target irradiation in order to make the connection with previous works on the RTI performed in this setting. Implementing one- and two-dimensional beam models, we find that these components can be expressed exactly in terms of the Fourier transform of the temporal beam profile. If T is the beam duration and ? its rotation frequency, "magic products" ?T can be identified which cancel the first harmonic of the deposited density, resulting in an improved irradiation symmetry. PMID:22587191

Bret, A; Piriz, A R; Tahir, N

2012-03-01

200

Harmonic analysis of irradiation asymmetry for cylindrical implosions driven by high-frequency rotating ion beams  

NASA Astrophysics Data System (ADS)

Cylindrical implosions driven by intense heavy ion beams should be instrumental in the near future for study of high-energy-density matter. By rotating the beam by means of a high-frequency wobbler, it should be possible to deposit energy in the outer layers of a cylinder, compressing the material deposited in its core. The beam's temporal profile should, however, generate an inevitable irradiation asymmetry likely to feed the Rayleigh-Taylor instability (RTI) during the implosion phase. In this paper, we compute the Fourier components of the target irradiation in order to make the connection with previous works on the RTI performed in this setting. Implementing one- and two-dimensional beam models, we find that these components can be expressed exactly in terms of the Fourier transform of the temporal beam profile. If T is the beam duration and ? its rotation frequency, “magic products” ?T can be identified which cancel the first harmonic of the deposited density, resulting in an improved irradiation symmetry.

Bret, A.; Piriz, A. R.; Tahir, N.

2012-03-01

201

Analysis of fragmentation in shock physics simulation  

Microsoft Academic Search

Analyzing shock physics, which can involve high energies, high velocity materials, and highly variable results, is challenging. Very little can be measured during a shock physics experiment. Most experimental data is collected in the aftermath. High-fidelity simulations using codes like CTH are possible, but require a significant amount of post processing to properly understand the results. Physical structures and their

Kenneth Moreland; C. Charles Law; L. Ice; D. Karelitz

2008-01-01

202

Fundamental analysis and ex vivo validation of thermal lesion mapping using harmonic motion imaging for focused ultrasound (HMIFU)  

NASA Astrophysics Data System (ADS)

Harmonic Motion Imaging for Focused Ultrasound (HMIFU) is a novel high-intensity focused ultrasound (HIFU) therapy monitoring method with feasibilities demonstrated in vitro, ex vivo and in vivo. Its principle is based on Amplitude-modulated (AM) - Harmonic Motion Imaging (HMI), an oscillatory radiation force used for imaging the tissue mechanical response during thermal ablation. In this study, a theoretical framework of HMIFU is presented, comprising a customized nonlinear wave propagation model, a finite-element (FE) analysis module, and an image-formation model. The objective of this study is to develop such a framework in order to 1) assess the fundamental performance of HMIFU in detecting HIFU lesions based on the change in tissue apparent elasticity, i.e., the increasing Young's modulus, and the HIFU lesion size with respect to the HIFU exposure time and 2) validate the simulation findings ex vivo. The same HMI and HMIFU parameters as in the experimental studies were used, i.e., 4.5-MHz HIFU frequency and 25-Hz AM frequency. For a lesion-to-background Young's modulus ratio of 3, 6, and 9, the estimated HMI displacement ratios were equal to 1.65, 3.19, 4.59, respectively. In experiments, the HMI displacement followed a similar increasing trend of 1.19, 1.28, 1.78 at 10-s, 20-s, and 30-s HIFU exposure, respectively. In addition, moderate agreement in lesion size growth was also found in both simulations (16.2, 73.1 and 334.7 mm2) and experiments (26.2, 94.2 and 206.2 mm2). Therefore, the feasibility of HMIFU for HIFU lesion detection based on the underlying tissue elasticity changes was verified through the developed theoretical framework, i.e., validation of the fundamental performance of the HMIFU system for lesion detection, localization and quantification, was demonstrated both theoretically and ex vivo.

Hou, Gary Y.; Luo, Jianwen; Maleke, Caroline; Vappou, Jonathan; Marquet, Fabrice; Konofagou, Elisa E.

2012-10-01

203

Harmonics and Fourier Series Model  

NSDL National Science Digital Library

The Ejs Harmonics and Fourier Series model displays the sum of harmonics via a Fourier series to yield a new wave. The amplitude of each harmonic as well as the phase of that harmonic can be changed via sliders. In addition, several pre-set functions can be chosen to display. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Harmonics and Fourier Series model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_ehu_oscillations_harmonics.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for classical mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Aguirregabiria, Juan

2008-11-11

204

Molecular structure, Normal Coordinate Analysis, harmonic vibrational frequencies, Natural Bond Orbital, TD-DFT calculations and biological activity analysis of antioxidant drug 7-hydroxycoumarin  

NASA Astrophysics Data System (ADS)

In this work, we report harmonic vibrational frequencies, molecular structure, NBO and HOMO, LUMO analysis of Umbelliferone also known as 7-hydroxycoumarin (7HC). The optimized geometric bond lengths and bond angles obtained by computation (monomer and dimmer) shows good agreement with experimental XRD data. Harmonic frequencies of 7HC were determined and analyzed by DFT utilizing 6-311+G(d,p) as basis set. The assignments of the vibrational spectra have been carried out with the help of Normal Coordinate Analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). The change in electron density (ED) in the ?* and ?* antibonding orbitals and stabilization energies E(2) have been calculated by Natural Bond Orbital (NBO) analysis to give clear evidence of stabilization originating in the hyperconjugation of hydrogen-bonded interaction. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. The simulated spectra satisfactorily coincides with the experimental spectra. Microbial activity of studied compounds was tested against Staphylococcus aureus, Streptococcus pyogenes, Bacillus subtilis, Escherichia coli, Psuedomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, Shigella flexneri, Salmonella typhi and Enterococcus faecalis.

Sebastian, S.; Sylvestre, S.; Jayarajan, D.; Amalanathan, M.; Oudayakumar, K.; Gnanapoongothai, T.; Jayavarthanan, T.

2013-01-01

205

Harmonic analysis and FPGA implementation of SHE controlled three phase CHB 11-level inverter in MV drives using deterministic and stochastic optimization techniques.  

PubMed

With the advancements in semiconductor technology, high power medium voltage (MV) Drives are extensively used in numerous industrial applications. Challenging technical requirements of MV Drives is to control multilevel inverter (MLI) with less Total harmonic distortion (%THD) which satisfies IEEE standard 519-1992 harmonic guidelines and less switching losses. Among all modulation control strategies for MLI, Selective harmonic elimination (SHE) technique is one of the traditionally preferred modulation control technique at fundamental switching frequency with better harmonic profile. On the other hand, the equations which are formed by SHE technique are highly non-linear in nature, may exist multiple, single or even no solution at particular modulation index (MI). However, in some MV Drive applications, it is required to operate over a range of MI. Providing analytical solutions for SHE equations during the whole range of MI from 0 to 1, has been a challenging task for researchers. In this paper, an attempt is made to solve SHE equations by using deterministic and stochastic optimization methods and comparative harmonic analysis has been carried out. An effective algorithm which minimizes %THD with less computational effort among all optimization algorithms has been presented. To validate the effectiveness of proposed MPSO technique, an experiment is carried out on a low power proto type of three phase CHB 11- level Inverter using FPGA based Xilinx's Spartan -3A DSP Controller. The experimental results proved that MPSO technique has successfully solved SHE equations over all range of MI from 0 to 1, the %THD obtained over major range of MI also satisfies IEEE 519-1992 harmonic guidelines too. PMID:24010030

Vesapogu, Joshi Manohar; Peddakotla, Sujatha; Kuppa, Seetha Rama Anjaneyulu

2013-01-01

206

Cost and performance analysis of physical security systems  

SciTech Connect

Analysis of cost and performance of physical security systems can be a complex, multi-dimensional problem. There are a number of point tools that address various aspects of cost and performance analysis. Increased interest in cost tradeoffs of physical security alternatives has motivated development of an architecture called Cost and Performance Analysis (CPA), which takes a top-down approach to aligning cost and performance metrics. CPA incorporates results generated by existing physical security system performance analysis tools, and utilizes an existing cost analysis tool. The objective of this architecture is to offer comprehensive visualization of complex data to security analysts and decision-makers.

Hicks, M.J. [Sandia National Labs., Albuquerque, NM (United States); Yates, D.; Jago, W.H.; Phillips, A.W. [Tecolote Research, Inc., Santa Barbara, CA (United States)

1998-04-01

207

A probabilistic approach to the dynamic analysis of ducts subjected to multibase harmonic and random excitation. [for Space Shuttle Main Engine  

NASA Technical Reports Server (NTRS)

The dynamic behavior of the discharge duct of the high-pressure oxidizer turbopump of a cryogenic rocket motor is investigated analytically. The probabilistic analysis program NESSUS (Numerical Evaluation of Stochastic Structures Under Stress; Cruse et al., 1988) is used to treat the uncertainties due to random and harmonic excitation (e.g., pump noise, pump-induced harmonics, and combustion noise), variations in engine inlet pressure, and changes in system damping. The load modeling procedure, the variation in power-spectral density in different zones of the engine structure, and the dynamic structural-analysis technique are described, and the numerical results of the NESSUS analysis are presented in extensive tables and graphs and discussed in detail.

Debchaudhury, Amit; Rajagopal, K. R.; Ho, H.; Newell, J. F.

1990-01-01

208

Application of multilayer mirror for harmonic analysis in soft X-ray region  

NASA Astrophysics Data System (ADS)

Order contamination in soft x-ray beamline is a severe problem which poses difficulty in various analysis techniques. Generally grating analyzer is used to estimate the higher order contribution where poor knowledge of wall and land roughness contribution makes it difficult to get theoretical fit and so analysis gives qualitative estimation only. Here we demonstrate the application of multilayer mirror for accurate determination of order contamination in Toroidal grating monochromator (TGM) at reflectivity beamline of Indus-1. We used a Mo/Si multilayer of d~100Å period to quantify 2nd and 3rd order composition to identify order contamination below 0.5% or better.

Modi, Mohammed H.; Gupta, R. K.; Lodha, G. S.

2012-06-01

209

Chemistry 160: Physical Measurements and Analysis  

NSDL National Science Digital Library

This site contains lab experiments for both analytical and physical chemical measurements. There are 6 analytical experiments: data acquisition, AAS, voltammetry, ASV, GC-MS, stop-flow kinetics and HPLC. Experiments use real samples and are ready for implementation.

Steinmetz, Wayne E.

2011-02-14

210

Methodological considerations for the harmonization of non-cholesterol sterol bio-analysis.  

PubMed

Non-cholesterol sterols (NCS) are used as surrogate markers of cholesterol metabolism which can be measured from a single blood sample. Cholesterol precursors are used as markers of endogenous cholesterol synthesis and plant sterols are used as markers of cholesterol absorption. However, most aspects of NCS analysis show wide variability among researchers within the area of biomedical research. This variability in methodology is a significant contributor to variation between reported NCS values and hampers the confidence in comparing NCS values across different research groups, as well as the ability to conduct meta-analyses. This paper summarizes the considerations and conclusions of a workshop where academic and industrial experts met to discuss NCS measurement. Highlighted is why each step in the analysis of NCS merits critical consideration, with the hopes of moving toward more standardized and comparable NCS analysis methodologies. Alkaline hydrolysis and liquid-liquid extraction of NCS followed by parallel detection on GC-FID and GC-MS is proposed as an ideal methodology for the bio-analysis of NCS. Furthermore the importance of cross-comparison or round robin testing between various groups who measure NCS is critical to the standardization of NCS measurement. PMID:24674990

Mackay, Dylan S; Jones, Peter J H; Myrie, Semone B; Plat, Jogchum; Lütjohann, Dieter

2014-04-15

211

The physics analysis tools project for the ATLAS experiment  

NASA Astrophysics Data System (ADS)

The Large Hadron Collider is expected to start colliding proton beams in 2009. The enormous amount of data produced by the ATLAS experiment (~1 PB per year) will be used in searches for the Higgs boson and Physics beyond the standard model. In order to meet this challenge, a suite of common Physics Analysis Tools has been developed as part of the Physics Analysis software project. These tools run within the ATLAS software framework, ATHENA, covering a wide range of applications. There are tools responsible for event selection based on analysed data and detector quality information, tools responsible for specific physics analysis operations including data quality monitoring and physics validation, and complete analysis toolkits (frameworks) with the goal to aid the physicist to perform his analysis hiding the details of the ATHENA framework.

Lenzi, Bruno; ATLAS Collaboration

2012-12-01

212

An SQL-based approach to physics analysis  

NASA Astrophysics Data System (ADS)

As part of the CERN openlab collaboration a study was made into the possibility of performing analysis of the data collected by the experiments at the Large Hadron Collider (LHC) through SQL-queries on data stored in a relational database. Currently LHC physics analysis is done using data stored in centrally produced "ROOT-ntuple" files that are distributed through the LHC computing grid. The SQL-based approach to LHC physics analysis presented in this paper allows calculations in the analysis to be done at the database and can make use of the database's in-built parallelism features. Using this approach it was possible to reproduce results for several physics analysis benchmarks. The study shows the capability of the database to handle complex analysis tasks but also illustrates the limits of using row-based storage for storing physics analysis data, as performance was limited by the I/O read speed of the system.

Limper, Maaike, Dr

2014-06-01

213

Geometric diffusions as a tool for harmonic analysis and structure definition of data: Diffusion maps  

PubMed Central

We provide a framework for structural multiscale geometric organization of graphs and subsets of \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{\\mathbb{R}}^{n}\\end{equation*}\\end{document}. We use diffusion semigroups to generate multiscale geometries in order to organize and represent complex structures. We show that appropriately selected eigenfunctions or scaling functions of Markov matrices, which describe local transitions, lead to macroscopic descriptions at different scales. The process of iterating or diffusing the Markov matrix is seen as a generalization of some aspects of the Newtonian paradigm, in which local infinitesimal transitions of a system lead to global macroscopic descriptions by integration. We provide a unified view of ideas from data analysis, machine learning, and numerical analysis.

Coifman, R. R.; Lafon, S.; Lee, A. B.; Maggioni, M.; Nadler, B.; Warner, F.; Zucker, S. W.

2005-01-01

214

Covariant harmonic oscillators: 1973 revisited  

NASA Technical Reports Server (NTRS)

Using the relativistic harmonic oscillator, a physical basis is given to the phenomenological wave function of Yukawa which is covariant and normalizable. It is shown that this wave function can be interpreted in terms of the unitary irreducible representations of the Poincare group. The transformation properties of these covariant wave functions are also demonstrated.

Noz, M. E.

1993-01-01

215

Analysis of star pair latitudes. [earth tides tesseral harmonics, and polar wandering  

NASA Technical Reports Server (NTRS)

Star pair latitude observations forming the basis for the pole positions reported by the International Polar Motion Service (IPMS) are processed to produce a mean pole position. However, the time series of raw observations contains high frequency information which is lost in the calculation of the mean pole. Analysis of 2931 star pair observations reveals a possible large excitation at one cycle per solar day. The average power level in the frequency band of the tesseral tides is seen to be high, although the peaks do not occur at the expected tidal frequencies.

Graber, M. A.

1978-01-01

216

New marine harmonic standards  

Microsoft Academic Search

To address concerns associated with electrical power system harmonic distortion on ships and offshore oil rigs and platforms, marine regulating bodies have introduced strict new harmonic standards. These standards define the acceptable level of harmonic voltage distortion allowed on the vessels they certify. High-harmonic distortion levels are appearing as a result of the increased use of power-electronic drive converters for

Tony Hoevenaars; Ian Evans; Andy Lawson

2010-01-01

217

Mean squared displacement analysis of an-harmonic behaviour in lyophilised proteins  

NASA Astrophysics Data System (ADS)

The temperature dependence of the mean squared displacement (msd), , determined from three lyophilised proteins (apoferritin, green fluorescent protein and insulin) observed over two different experimental time scales is presented. The analysis of elastic incoherent neutron scattering data. Fast pico-second (ps) dynamics appear insensitive to the secondary structure of the proteins. However, the arrangement of the amino acids appears to play a role at longer nano-second (ns) timescales. The effect of hydration on is also considered. For apoferritin and green fluorescent protein, elevated hydration levels appear to suppress fast ps dynamic modes when T < 240 K rendering the material more rigid than when in its lyophilised state.

Telling, Mark T. F.; Howells, Spencer; Combet, Jérôme; Clifton, Luke A.; García Sakai, Victoria

2013-10-01

218

Simple Harmonic Oscillator Model  

NSDL National Science Digital Library

The Ejs Simple Harmonic Oscillator model displays the dynamics of a ball attached to an ideal spring. The spring is initially stretched and the ball has zero initial velocity. The initial position of the ball can be changed by click-dragging the ball when the simulation is paused. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Simple Harmonic Oscillator model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_osc_SHO.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for Newtonian mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2008-07-05

219

Physics and Analysis at a Hadron Collider - Searching for New Physics (2/3)  

SciTech Connect

This is the second lecture of three which together discuss the physics of hadron colliders with an emphasis on experimental techniques used for data analysis. This second lecture discusses techniques important for analyses searching for new physics using the CDF B_s --> mu+ mu- search as a specific example. The lectures are aimed at graduate students.

None

2010-01-20

220

Physics and Analysis at a Hadron Collider - Searching for New Physics (2/3)  

ScienceCinema

This is the second lecture of three which together discuss the physics of hadron colliders with an emphasis on experimental techniques used for data analysis. This second lecture discusses techniques important for analyses searching for new physics using the CDF B_s --> mu+ mu- search as a specific example. The lectures are aimed at graduate students.

221

Physics and Analysis at a Hadron Collider - Searching for New Physics (2/3)  

ScienceCinema

This is the second lecture of three which together discuss the physics of hadron colliders with an emphasis on experimental techniques used for data analysis. This second lecture discusses techniques important for analyses searching for new physics using the CDF B_s --> mu+ mu- search as a specific example. The lectures are aimed at graduate students.

None

2011-10-06

222

Design of dispersion section for the ATF harmonic generation FEL  

SciTech Connect

We present an analysis of the dispersion magnet for the high gain harmonic generation experiment to be carried out at the Accelerator Test Facility at BNL. The purpose of the dispersion magnet is to convert energy modulation of the electron beam into spatial bunching. For the dispersion magnet, we discuss the physical requirements, analyze the magnetic design, determine the focusing properties, and consider the effect on the FEL gain of departures from idea behavior on the FEL gain.

Zhang, X.; Ben-Zvi, I.; Ingold, G.; Krinsky, S.; Yu, L.H.

1992-10-01

223

Design of dispersion section for the ATF harmonic generation FEL  

SciTech Connect

We present an analysis of the dispersion magnet for the high gain harmonic generation experiment to be carried out at the Accelerator Test Facility at BNL. The purpose of the dispersion magnet is to convert energy modulation of the electron beam into spatial bunching. For the dispersion magnet, we discuss the physical requirements, analyze the magnetic design, determine the focusing properties, and consider the effect on the FEL gain of departures from idea behavior on the FEL gain.

Zhang, X.; Ben-Zvi, I.; Ingold, G.; Krinsky, S.; Yu, L.H.

1992-01-01

224

Transmission characteristics of cyclotron harmonic waves in plasma  

Microsoft Academic Search

In recent years the importance of cyclotron harmonic waves has become apparent in many branches of plasma physics. For example, it has been demonstrated that they are involved in the anomalously high noise radiation near the electron cyclotron harmonic frequencies that has been observed from thermonuclear fusion study devices, and that they can explain the cyclotron harmonic resonances observed in

F. W. Crawford; H. H. Weiss

1966-01-01

225

Atmospheric cloud physics thermal systems analysis  

NASA Technical Reports Server (NTRS)

Engineering analyses performed on the Atmospheric Cloud Physics (ACPL) Science Simulator expansion chamber and associated thermal control/conditioning system are reported. Analyses were made to develop a verified thermal model and to perform parametric thermal investigations to evaluate systems performance characteristics. Thermal network representations of solid components and the complete fluid conditioning system were solved simultaneously using the Systems Improved Numerical Differencing Analyzer (SINDA) computer program.

1977-01-01

226

Exploratory versus Confirmatory Factor Analysis of Collegiate Physical Fitness.  

ERIC Educational Resources Information Center

Twenty-one variables believed to be important indicators of health related physical fitness were measured on male and female college students between 1991 and 1993 (n=433). Exploratory and confirmatory factor analytic techniques were used in an attempt to derive important components of physical fitness. The exploratory factor analysis identified…

Mead, Tim P.; Legg, David L.

227

Dimensional Analysis in Physics and the Buckingham Theorem  

ERIC Educational Resources Information Center

Dimensional analysis is a simple, clear and intuitive method for determining the functional dependence of physical quantities that are of importance to a certain process. However, in physics textbooks, very little space is usually given to this approach and it is often presented only as a diagnostic tool used to determine the validity of…

Misic, Tatjana; Najdanovic-Lukic, Marina; Nesic, Ljubisa

2010-01-01

228

Module 5: Analysis of Physics Problems and Test Questions  

Microsoft Academic Search

You may be wondering how to apply the concept of developmental stages in your physics teaching, To help you with this, we have prepared modules 5-11 dealing with differing aspects of instruction. Module 5 concentrates on the analysis and writing of physics problems and test questions. As you read the examples we have selected, keep in mind the characterisrtics of

Francis P. Collea; Robert Fuller; Robert Karplus; Lester G. Paldy; John W. Renner

1975-01-01

229

Analysis of interface carrier accumulation and relaxation in pentacene/C60 double-layer organic solar cell by impedance spectroscopy and electric-field-induced optical second harmonic generation  

NASA Astrophysics Data System (ADS)

By using the impedance spectroscopy (IS) and optical electric-field-induced second harmonic generation (EFISHG) measurement, interfacial carrier relaxation in pentacene/C60 double-layer organic solar cell (OSC) has been analyzed. The IS measurements showed that the interfacial carrier relaxation time was diminished 70 times under photo illumination, due to the increase of carrier density caused by the photovoltaic effect. The equivalent circuit analysis using a Maxwell-Wagner effect model well accounted for the IS results. On the other hand, the EFISHG measurements directly probed the interfacial carrier behaviors caused by the photovoltaic effect. The results showed the suppression of the Maxwell-Wagner type carrier relaxation in OSCs by applying a voltage corresponding to the open circuit voltage Voc. EFISHG measurement coupled with IS measurement provides a clear physics picture of interfacial phenomena related to the photovoltaic effect in OSCs.

Chen, Xiangyu; Taguchi, Dai; Shino, Tatsunori; Manaka, Takaaki; Iwamoto, Mitsumasa

2011-10-01

230

Second Harmonic Generation Imaging Microscopy: Applications to Diseases Diagnostics  

PubMed Central

Second Harmonic Generation microscopy has emerged as a powerful new optical imaging modality. This Feature describes its chemical and physical principles and highlights current applications in disease diagnostics.

Campagnola, Paul

2011-01-01

231

Spherical Harmonics Analysis of the ECMWF Global Wind Fields at the 10-Meter Height Level During 1985: A Collection of Figures Illustrating Results  

NASA Technical Reports Server (NTRS)

Half-daily global wind speeds in the east-west (u) and north-south (v) directions at the 10-meter height level were obtained from the European Centre for Medium Range Weather Forecasts (ECMWF) data set of global analyses. The data set covered the period 1985 January to 1995 January. A spherical harmonic expansion to degree and order 50 was used to perform harmonic analysis of the east-west (u) and north-south (v) velocity field components. The resulting wind field is displayed, as well as the residual of the fit, at a particular time. The contribution of particular coefficients is shown. The time variability of the coefficients up to degree and order 3 is presented. Corresponding power spectrum plots are given. Time series analyses were applied also to the power associated with degrees 0-10; the results are included.

Sanchez, Braulio V.; Nishihama, Masahiro

1997-01-01

232

Higher harmonic control for rotary wing aircraft  

NASA Technical Reports Server (NTRS)

Higher Harmonic Control reduces helicopter airframe vibration through the exercise of rotor blade pitch control at frequencies that are higher harmonics of rotor rotation. Analysis wind tunnel tests and flight tests of this technology with an OH-6A helicopter have led to vibration reduction levels of the order of more than 80 percent. Blade feathering capability at rotor speed harmonics other than the first also promises the improvement of such rotor characteristics as acoustics, aerodynamic efficiency and ground resonance.

Gupta, B. P.; Logan, A. H.; Wood, E. R.

1984-01-01

233

Applied harmonic analysis  

NASA Astrophysics Data System (ADS)

Recent work by the CUNY group under the direction of Professor Louis Auslander has continued to study application of the Weil transform to radar signal processing and, in a parallel effort, to multi-access spread spectrum communications. The main thrust of the work is the relationship between the Weil transform of a waveform and the ambiguity surface of the wave-form. The study of this relationship has led to a fundamental observation: the cancellation properties of a waveform necessary for the creation of a thumbtack-like ambiguity surface may be viewed as arising from the pattern of zeros and the non-trivial winding numbers of the Weil transform of the waveform. This point of view is exposited and used to reinterpret classical radar waveform design techniques, while also providing a new method for radar waveform design. Additionally, a new technique for modifying or shaping waveforms has been developed. This consists of changing a waveforms has been developed. This consists of changing a waveform by multiplying its Weil transform by doubly-periodic functions and taking the inverse Weil transform to produce a new signal.

Auslander, Louis

1993-08-01

234

Applied harmonic analysis  

Microsoft Academic Search

Recent work by the CUNY group under the direction of Professor Louis Auslander has continued to study application of the Weil transform to radar signal processing and, in a parallel effort, to multi-access spread spectrum communications. The main thrust of the work is the relationship between the Weil transform of a waveform and the ambiguity surface of the wave-form. The

Louis Auslander

1993-01-01

235

Industrial harmonic analysis system for magnetic measurements of SSC collider arc and high energy booster corrector magnets.  

National Technical Information Service (NTIS)

The SSCL collider arc and high energy booster corrector magnets are 50 mm bore cryogenic magnets. The integral strength and harmonics will be measured by industry at full current at 4.2 K and at plus and minus 400 mA at room temperature. Dipoles, quadrupo...

M. I. Green R. Sponsel C. Sylvester

1993-01-01

236

Simulation and analysis of magnetic resonance elastography wave images using coupled harmonic oscillators and Gaussian local frequency estimation  

Microsoft Academic Search

New methods for simulating and analyzing Magnetic Resonance Elastography (MRE) images are introduced. To simulate a two-dimensional shear wave pattern, the wave equation is solved for a field of coupled harmonic oscillators with spatially varying coupling and damping coefficients in the presence of an external force. The spatial distribution of the coupling and the damping constants are derived from an

Jürgen Braun; Gerd Buntkowsky; Johannes Bernarding; Thomas Tolxdorff; Ingolf Sack

2001-01-01

237

Signal-to-noise ratio analysis for a back-action-evading measurement on a double harmonic oscillator  

NASA Astrophysics Data System (ADS)

We compute the sensitivity of a double harmonic oscillator system inserted in a back-action-evasion scheme of electromechanical transduction. This sensitivity is presented by deriving the effective temperature and the optimum observation time of the detector. Finally, the performances of this scheme on a resonant gravitational wave antenna at low temperature are discussed.

Cinquegrana, C.; Majorana, E.; Pergola, N.; Puppo, P.; Rapagnani, P.; Ricci, F.

1994-09-01

238

Dimensional analysis in physics and the Buckingham theorem  

NASA Astrophysics Data System (ADS)

Dimensional analysis is a simple, clear and intuitive method for determining the functional dependence of physical quantities that are of importance to a certain process. However, in physics textbooks, very little space is usually given to this approach and it is often presented only as a diagnostic tool used to determine the validity of dependences otherwise obtained. This paper presents the basics of dimensional analysis in two cases: the resistance force of the fluid that occurs when a body moves through it and the speed of propagation of waves on water. After that, a general approach to dimensional analysis based on the Buckingham theorem is shown. The material presented in the paper could be useful to both students of physics and physics graduates.

Misic, Tatjana; Najdanovic-Lukic, Marina; Nesic, Ljubisa

2010-07-01

239

Simple Harmonic Motion in Harmonic Plane Waves.  

ERIC Educational Resources Information Center

Discusses the distribution of kinetic and potential energy in transverse and longitudinal waves and examines the transmission of power and momentum. This discussion is intended to aid in understanding the simple harmonic motion of a particle involved in the propagation of a harmonic mechanical plane wave. (HM)

Benumof, Reuben

1980-01-01

240

High-Speed Video Analysis in a Conceptual Physics Class  

ERIC Educational Resources Information Center

The use of probe ware and computers has become quite common in introductory physics classrooms. Video analysis is also becoming more popular and is available to a wide range of students through commercially available and/or free software. Video analysis allows for the study of motions that cannot be easily measured in the traditional lab setting…

Desbien, Dwain M.

2011-01-01

241

Accelerator physics analysis with an integrated toolkit  

SciTech Connect

Work is in progress on an integrated software toolkit for linear and nonlinear accelerator design, analysis, and simulation. As a first application, beamline'' and MXYZPTLK'' (differential algebra) class libraries, were used with an X Windows graphics library to build an user-friendly, interactive phase space tracker which, additionally, finds periodic orbits. This program was used to analyse a theoretical lattice which contains octupoles and decapoles to find the 20th order, stable and unstable periodic orbits and to explore the local phase space structure.

Holt, J.A.; Michelotti, L.; Satogata, T.

1992-08-01

242

Accelerator physics analysis with an integrated toolkit  

SciTech Connect

Work is in progress on an integrated software toolkit for linear and nonlinear accelerator design, analysis, and simulation. As a first application, ``beamline`` and ``MXYZPTLK`` (differential algebra) class libraries, were used with an X Windows graphics library to build an user-friendly, interactive phase space tracker which, additionally, finds periodic orbits. This program was used to analyse a theoretical lattice which contains octupoles and decapoles to find the 20th order, stable and unstable periodic orbits and to explore the local phase space structure.

Holt, J.A.; Michelotti, L.; Satogata, T.

1992-08-01

243

Plasma physics analysis of SERT-2 operation  

NASA Technical Reports Server (NTRS)

An analysis of the major plasma processes involved in the SERT 2 spacecraft experiments was conducted to aid in the interpretation of recent data. A plume penetration model was developed for neutralization electron conduction to the ion beam and showed qualitative agreement with flight data. In the SERT 2 configuration conduction of neutralization electrons between thrusters was experimentally demonstrated in space. The analysis of this configuration suggests that the relative orientation of the two magnetic fields was an important factor in the observed results. Specifically, the opposed field orientation appeared to provide a high conductivity channel between thrusters and a barrier to the ambient low energy electrons in space. The SERT 2 neutralizer currents with negative neutralizer biases were up to about twice the theoretical prediction for electron collection by the ground screen. An explanation for the higher experimental values was a possible conductive path from the neutralizer plume to a nearby part of the ground screen. Plasma probe measurements of SERT 2 gave the clearest indication of plasma electron temperature, with normal operation being near 5 eV and discharge only operation near 2 eV.

Kaufman, H. R.

1980-01-01

244

Harmonic synchronizations of spacetime  

SciTech Connect

The spacetime slicings associated with a harmonic time coordinate (harmonic synchronizations) are considered and their usefulness in the field of numerical relativity is studied. Harmonic synchronizations are shown to avoid singularities in the same way that the widely used maximal slicings do. Both kinds of slicing are compared in stationary axisymmetric spacetimes, homogeneous cosmological models, and Kerr-Newman black holes.

Bona, C.; Masso, J.

1988-10-15

245

Global analysis of crisis in twin-well Duffing system under harmonic excitation in presence of noise  

Microsoft Academic Search

Evolution of a crisis in a twin-well Duffing system under a harmonic excitation in presence of noise is explored in detail by the generalized cell mapping with digraph (GCMD in short) method. System parameters are chosen in the range that there co-exist chaotic attractors and\\/or chaotic saddles, together with their evolution. Due to noise effects, chaotic attractors and chaotic saddles

Wei Xu; Qun He; Tong Fang; Haiwu Rong

2005-01-01

246

Simulation and analysis of magnetic resonance elastography wave images using coupled harmonic oscillators and Gaussian local frequency estimation  

Microsoft Academic Search

Abstract New methods,for simulating and analyzing Magnetic Resonance Elastography (MRE) images,are introduced. To simulate a two- dimensional shear wave pattern, the wave equation is solved for a field of coupled harmonic oscillators with spatially varying coupling and damping,coefficients in the presence of an external force. The spatial distribution of the coupling and the damping,constants are derived from an MR image,of

Ju Rgen Braun; Gerd Buntkowsky; Johannes Bernarding; Thomas Tolxdorff; Ingolf Sack

247

PARAMETER ANALYSIS FOR A HIGH-GAIN HARMONIC GENERATION FEL BY NUMERICAL CALCULATION BASED ON 1D THEORY  

Microsoft Academic Search

High-gain harmonic generation (HGHG) free-electron laser (FEL) is an important candidate for fourth- generation light source. Lots of research works about it have been done all along. Recently a further 1D theory about HGHG FEL has been developed. It considers the effects of different parameters for the whole process. An initial program based on this theory has been made. In

Li Yuhui; Jia Qika; Zhang Shancai

248

Quantitative analysis of third harmonic generation of XUV radiation in a cell and a CW free jet of carbon monoxide  

Microsoft Academic Search

The two-photon resonant third-order nonlinear susceptibility of a molecular gas is calculated. The variations of this susceptibility, with the rotational quantum numbers of the resonant states, are given in the case of two singlet states of different symmetries, Sigma and Pi. In the experiment, third harmonic generation of XUV light (94.5-97.5 nm) is obtained with and without two-photon resonance. The

F. Aguillon; A. Lebehot; J. Rousseau; R. Campargue

1987-01-01

249

Online Data Collection and Analysis in Introductory Physics  

NASA Astrophysics Data System (ADS)

Online implementation of physics learning materials may present a powerful method of data collection for physics education research, in addition to being useful for supplemental instruction. This may have implications for composite instruction and research designs. We have developed three lessons on Newton's laws and implemented them on the Internet. The lessons ask students to make observations and measurements using video clips, perform calculations and answer open-ended questions. Responses are collected via an online response system. One hundred ten university students enrolled in an algebra-based physics course and 30 high school physics students worked through some or all of our lessons, and their responses were collected. We present a qualitative and quantitative analysis of their responses and assess the implications for optimal design of online lesson materials for collecting meaningful data about students' understanding of basic physics concepts.

Nakamura, Christopher M.; Murphy, Sytil K.; Juma, Nasser M.; Rebello, N. Sanjay; Zollman, Dean

2009-11-01

250

HEPDOOP: High-Energy Physics Analysis using Hadoop  

NASA Astrophysics Data System (ADS)

We perform a LHC data analysis workflow using tools and data formats that are commonly used in the "Big Data" community outside High Energy Physics (HEP). These include Apache Avro for serialisation to binary files, Pig and Hadoop for mass data processing and Python Scikit-Learn for multi-variate analysis. Comparison is made with the same analysis performed with current HEP tools in ROOT.

Bhimji, W.; Bristow, T.; Washbrook, A.

2014-06-01

251

Job analysis of nuclear power reactor health physics technicians  

Microsoft Academic Search

This report describes a project, an industry-wide Job Analysis of Nuclear Power Reactor Health Physics Technicians (HPTs), conducted by Brookhaven National Laboratory and Analysis and Technology, Inc. to provide the industry with job-performance data that can be used in systematically defining training programs in terms of required job functions responsibilities, and performance standards. The job-analysis methodology is consistent with that

L. T. Davis; T. J. Mazour; P. V. Clark; R. C. Todd; F. J. Marotta

1984-01-01

252

Nondeducibility-Based Analysis of Cyber-Physical Systems  

Microsoft Academic Search

Controlling information flow in a cyber-physical system (CPS) is challenging because cyber domain decisions and actions manifest\\u000a themselves as visible changes in the physical domain. This paper presents a nondeducibility-based observability analysis for\\u000a CPSs. In many CPSs, the capacity of a low-level (LL) observer to deduce high-level (HL) actions ranges from limited to none.\\u000a However, a collaborative set of observers

Thoshitha Gamage; Bruce McMillin

2009-01-01

253

Directional harmonics in Doppler effect  

NASA Astrophysics Data System (ADS)

A mathematical theory is presented which shows that a moving reflector of waves gives rise to harmonics of the Doppler shift in the input impedance of the transmission medium. The analysis can be used to explain new 'direction of motion' detection phenomena.

Lazarus, M. J.; Somekh, M. G.; Novak, S.; Pantoja, F. R.

1981-01-01

254

Harmonic nanoparticles for regenerative research.  

PubMed

In this visualized experiment, protocol details are provided for in vitro labeling of human embryonic stem cells (hESC) with second harmonic generation nanoparticles (HNPs). The latter are a new family of probes recently introduced for labeling biological samples for multi-photon imaging. HNPs are capable of doubling the frequency of excitation light by the nonlinear optical process of second harmonic generation with no restriction on the excitation wavelength. Multi-photon based methodologies for hESC differentiation into cardiac clusters (maintained as long term air-liquid cultures) are presented in detail. In particular, evidence on how to maximize the intense second harmonic (SH) emission of isolated HNPs during 3D monitoring of beating cardiac tissue in 3D is shown. The analysis of the resulting images to retrieve 3D displacement patterns is also detailed. PMID:24836220

Ronzoni, Flavio; Magouroux, Thibaud; Vernet, Remi; Extermann, Jérôme; Crotty, Darragh; Prina-Mello, Adriele; Ciepielewski, Daniel; Volkov, Yuri; Bonacina, Luigi; Wolf, Jean-Pierre; Jaconi, Marisa

2014-01-01

255

Combining Computational Physics with Video Analysis in Tracker  

NSDL National Science Digital Library

In Spring 2007, introductory mechanics students at Cabrillo College used Tracker to compare 2D particle models with videos of real-world motion. After doing a traditional motion video analysis lab, students used both analytic (position functions) and dynamic (force functions and initial conditions for numerical solvers) models to draw overlays directly on their captured videos. The video thus provided a "reality check" while students explored different models, parameters and algorithms. In addition to the visual overlays, the models generated "experimental data" for graphing and analysis just like experimental (student-marked) tracks. This paper will describe my own and my students' experiences with this first exposure to computational physics in the curriculum. Tracker is a JAVA video/image analysis tool developed by the Open Source Physics Project. The Open Source Physics project is supported in part by the National Science Foundation grants DUE-0126439 and DUE-0442481.

Brown, Douglas

2010-10-14

256

Harmonic considerations for electrical distribution feeders  

SciTech Connect

Harmonics on the electric power distribution system can cause motor overheating, capacitor failures, watthour meter error, and relay malfunctions. The degree of problems caused by harmonics is greatly dependent on the characteristics of the distribution feeder. A typical distribution feeder can absorb a considerable percentage of its capacity in harmonic currents without ill effects. However, power factor correction capacitors can cause resonances near harmonic voltages that can result in intolerable distortion. Both motor loads and resistive loads can decrease the effet of resonance significatnly. This report describes useful techniques to analyze, suppress, and measure harmonics on distribution feeders. Applicable areas for manual analysis and computer analysis are explained. The basic formulae are presented as well as sophisticated omputer methods. Emphasis is placed on the fundamental principle. Models of harmonic-producing devices are presented and their limitations discussed. Most distribution feeder harmonics analyses can be performed using simple current source models. Filtering of specific loads and general, dispersed load is discussed. The fundamental principle in filtering distribution feeders is to shorten the harmonic current path. 3-dimensional plots enhance the understanding of the filtering action. Equipment and procedures for making measurements are described.

Not Available

1988-03-01

257

A joint torque sensing technique for robots with harmonic drives  

Microsoft Academic Search

A joint torque sensing technique for robots with harmonic drives is proposed. Elasticity of harmonic drives is utilized to measure the joint torque. The technique provides joint torque sensing without reducing the stiffness of the robot and changing the mechanical structure of the joints. A finite-element analysis of flexsplines, which are flexible thin cups made from steel in harmonic drives,

Minoru Hashimoto; Yoshihide Kiyosawa; H. Hirabayashi; R. P. Paul

1991-01-01

258

Synchronization of networked harmonic oscillators under nonlinear protocols  

Microsoft Academic Search

This paper deals with the synchronization of networked harmonic oscillators under nonlinear protocols. Some convergence analysis for such networked harmonic oscillators, both without and with a leader, are provided by means of algebraic graph theory, matrix theory and Lyapunov stability theory on dynamical systems. We show that the networked harmonic oscillators can achieve synchronization under nonlinear control input. Moreover, we

Shan Cheng; Gang Zhang; Lan Xiang; Jin Zhou

2010-01-01

259

An improved harmonic modeling technique for transmission network  

Microsoft Academic Search

For harmonic analysis it is not practically possible to model a large transmission network with its neighboring interconnected systems in detail due to computer time and memory limitations. Furthermore, a large number of outage contingencies has to be analyzed to compute harmonic impedance boundaries for filter designs. Current methods do not address modeling simplification errors and also accuracy of harmonic

M. F. Akram; T. H. Ortmeyer; J. A. Svoboda

1994-01-01

260

34 GHz second-harmonic peniotron oscillator  

NASA Astrophysics Data System (ADS)

Harmonic operation of gyro-devices has been proposed as a way to lower the magnetic field required to a level feasible with normal (i.e., non-superconducting) magnets. The problem is, however, that gyrotron efficiency drops dramatically at harmonics greater than two, making development of such a device of limited utility. A promising solution to this quandary is the development of a related device, the peniotron, which is believed capable of achieving both high efficiency and harmonic operation resulting in a reduction of the required axial magnetic field. Although the physics of the peniotron interaction, including its high electronic conversion efficiency, has been understood and experimentally verified, demonstration of characteristics consistent with a practical device has been more elusive. This is the goal of this effort---specifically, to demonstrate high device efficiency (defined as the actual power output as a fraction of the electron beam power) with an electron beam generated by a compact cusp electron gun consistent in size and performance with other microwave vacuum electron devices. The cavity design process revealed that the pi/2 mode couples easily to the output circular waveguide. In fact, the transition to circular waveguide produced such a low reflection coefficient that an iris was needed at the cavity output to achieve the desired Q. Integral couplers were also designed to couple directly into the slotted cavity for diagnostic purposes for simplicity in this proof-of-principle physics experiment. This eliminated the need for a high-power circular vacuum window and allowed the diagnostic coupling to be made in standard WR-28 rectangular waveguide. Although mode competition did prevent the second-harmonic peniotron mode from being tuned over its entire range of magnetic field, the peniotron mode was stable over a range sufficient to allow useful experimental data to be obtained. However, another unexpected problem which occurred during execution of the experiment was persistent arcing along the cusp gun high-voltage ceramic which prevented the gun from being operated at its full design voltage of 70 kV. The measured output power and efficiency was then reduced to about a third of that originally predicted. That is, a maximum peak power of approximately 35 kW and maximum efficiency of 18% was achieved. Significant post-test analysis revealed that the reduced operating voltage of the cusp gun degraded the operation of the device in several inter-related ways. First, the lower voltage shifted the desired peniotron interaction to a lower interaction magnetic field such that the maximum power which could have been achieved was right at the point of greatest interference from the competing mode. Secondly, the lower gun voltage resulted in a correspondingly lower beam power to drive the interaction. Finally, the beam optics of the cusp gun was designed for operation at 70 kV such that reduced beam voltage resulted in degradation of the beam quality. Nonetheless, the viability of the device was proven as the measured output power and device efficiency still represent unprecedented performance for a harmonic peniotron. Finally, analysis of the cavity design and competing mode characteristics indicate that a simple re-design of the cavity will result in a comparable design in which the competing fourth-harmonic gyrotron mode is removed. This design entails a slight change to the slot depth and vane angle of the four-vane cavity. Other parameters would not necessarily need to be changed and the modified device should achieve virtually the same results (power and efficiency) as originally predicted. Furthermore, with the competing mode removed (and assuming the gun arcing can be suppressed), the higher current available from the cusp gun could be exploited to achieve even higher output power than originally predicted. (Abstract shortened by UMI.)

Dressman, Lawrence Jude

261

IDA: An interactive data analysis environment for high energy physics  

NASA Astrophysics Data System (ADS)

Only in the last few years have computers used for high energy physics analysis allowed their users significant access to the CPU in an interactive mode. This capability has led to the development of the analysis system IDA, now widely used at SLAC for DST analysis. There are two elements to the system: a format for describing data whereby each element is given a name, and elements are grouped into structures reflecting the structure of the parent analysis program; and a stand-aline program allowing the user to interactively create plots involving any function of the saved quantities, subject to any condition.

Burnett, T. H.

1987-08-01

262

High order harmonic generation in rare gases  

SciTech Connect

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 {approximately}10{sup 13}-10{sup 14} W/cm{sup 2}) is focused into a dense ({approximately}10{sup l7} particles/cm{sup 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 {open_quotes}source{close_quotes}. 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.

Budil, K.S.

1994-05-01

263

Physical optics analysis of a beam waveguide with six reflectors  

Microsoft Academic Search

An efficient code for the analysis of beam waveguides and multireflector antennas by PO (physical optics) integration is presented. In the ELAB PO-code, there is no restriction on the number of reflectors, each reflector can be numerically specified to any shape, and the reflectors may be plane or parts of ellipsoids, with elliptical contours. The code has been applied to

P.-S. Kildal; Jacob Kuhnle; Kees van t'Klooster; Robert Graham

1990-01-01

264

Measurements of Extreme Physical Phenomena by Fourier Fringe Analysis  

NASA Astrophysics Data System (ADS)

The paper reviews recent applications of the Fourier transform method (FTM) of fringe pattern analysis to the measurements of extreme physical phenomena, such as those involving ultra fast optical pulses, extremely small atomic displacements, and unconventional electron or EUV waves, and shows how the advantages of FTM are exploited in these cutting edge application areas.

Takeda, Mitsuo

2010-04-01

265

Quantitative analysis of collagen fiber organization in injured tendons using Fourier transform-second harmonic generation imaging.  

PubMed

Fourier transform-second harmonic generation (FT-SHG) imaging is used as a technique for evaluating collagenase-induced injury in horse tendons. The differences in collagen fiber organization between normal and injured tendon are quantified. Results indicate that the organization of collagen fibers is regularly oriented in normal tendons and randomly organized in injured tendons. This is further supported through the use of additional metrics, in particular, the number of dark (no/minimal signal) and isotropic (no preferred fiber orientation) regions in the images, and the ratio of forward-to-backward second-harmonic intensity. FT-SHG microscopy is also compared with the conventional polarized light microscopy and is shown to be more sensitive to assessing injured tendons than the latter. Moreover, sample preparation artifacts that affect the quantitative evaluation of collagen fiber organization can be circumvented by using FT-SHG microscopy. The technique has potential as an assessment tool for evaluating the impact of various injuries that affect collagen fiber organization. PMID:21164843

Sivaguru, Mayandi; Durgam, Sushmitha; Ambekar, Raghu; Luedtke, David; Fried, Glenn; Stewart, Allison; Toussaint, Kimani C

2010-11-22

266

Higher-order sinusoidal input describing functions for the analysis of non-linear systems with harmonic responses  

NASA Astrophysics Data System (ADS)

For high-precision motion systems, modelling and control design specifically oriented at friction effects is instrumental. The sinusoidal input describing function theory represents an approximative mathematical framework for analysing non-linear system behaviour. This theory, however, limits the description of the non-linear system behaviour to a quasi-linear amplitude-dependent relation between sinusoidal excitation and sinusoidal response. In this paper, an extension to higher-order describing functions is realised by introducing the concept of the harmonics generator. The resulting higher-order sinusoidal input describing functions (HOSIDFs) relate the magnitude and phase of the higher harmonics of the periodic response of the system to the magnitude and phase of a sinusoidal excitation. Based on this extension two techniques to measure HOSIDFs are presented. The first technique is FFT based. The second technique is based on IQ (in-phase/quadrature-phase) demodulation. In a simulation, the measurement techniques have been tested by comparing the simulation results to analytically derived results from a known (backlash) non-linearity. In a subsequent practical case study both techniques are used to measure the changes in dynamic behaviour as a function of drive level due to friction in an electric motor. Both methods prove successful for measuring HOSIDFs.

Nuij, P. W. J. M.; Bosgra, O. H.; Steinbuch, M.

2006-11-01

267

Effective bandwidth extension by combined harmonics  

NASA Astrophysics Data System (ADS)

Originating from signal compression techniques in radar, a wide range of ultrasound encoded excitation approaches have been developed for increasing signal strength. These techniques have been extended to nonlinear applications by isolating higher harmonic signal components, thus offering higher signal-to-noise ratios along with the harmonic's increased radial focusing abilities and a potentially broader bandwidth relative to the fundamental. Unfortunately, such techniques can suffer artifacts caused by overlap between the harmonics. We have been investigating an alternative approach to nonlinear compression that combines the fundamental and higher harmonics, effectively treating them as a single band. This extended bandwidth permits a significant increase in the ability to compress a signal. Successfully implemented, the method would permit enhanced image resolution while benefiting from the increased SNR offered by encoding. Pulse-inverted sum and difference signals are first used to isolate even and odd harmonics. Matched filters specific to the source geometry and the transmit signal are then separately applied to each harmonic band. Verification experiments are performed using up the third harmonic resulting from an underwater chirp excitation. Analysis of signal peaks after scattering indicates increased compression using the extended bandwidth as compared to standard fundamental and 2nd-harmonic chirp compression. Further optimization of the compression by altering the transmission signal is also investigated. Overall, results establish the feasibility of extended bandwidth signal compression for simultaneously increasing SNR and signal resolution.

Clement, Gregory T.; Nomura, Hideyuki; Adachi, Hideo; Kamakura, Tomoo

2012-09-01

268

Data management, archiving, visualization and analysis of space physics data  

NASA Technical Reports Server (NTRS)

A series of programs for the visualization and analysis of space physics data has been developed at UCLA. In the course of those developments, a number of lessons have been learned regarding data management and data archiving, as well as data analysis. The issues now facing those wishing to develop such software, as well as the lessons learned, are reviewed. Modern media have eased many of the earlier problems of the physical volume required to store data, the speed of access, and the permanence of the records. However, the ultimate longevity of these media is still a question of debate. Finally, while software development has become easier, cost is still a limiting factor in developing visualization and analysis software.

Russell, C. T.

1995-01-01

269

Backscatter analysis of dihedral corner reflectors using physical optics and the physical theory of diffraction  

NASA Technical Reports Server (NTRS)

The backscatter cross-sections of dihedral corner reflectors in the azimuthal plane are presently determined by both physical optics (PO) and the physical theory of diffraction (PTD), yielding results for the vertical and horizontal polarizations. In the first analysis method used, geometrical optics is used in place of PO at initial reflections in order to maintain the planar character of the reflected wave and reduce the complexity of the analysis. In the second method, PO is used at almost every reflection in order to maximize the accuracy of the PTD solution at the expense of a rapid increase in complexity. Induced surface current densities and resulting cross section patterns are illustrated for the two methods.

Griesser, Timothy; Balanis, Constantine A.

1987-01-01

270

Harmon Craig (1926-2003)  

NASA Astrophysics Data System (ADS)

Harmon Craig, one of the great pioneers of isotope geochemistry died on 14 March after suffering a massive heart attack at his home in La Jolla, California. He was one day shy of his 77th birthday. Through an academic career of more than fifty years, Craig—or simply “Harmon,” as he was known throughout the world of geochemistry—made a remarkable number of fundamental and far-reaching contributions in a wide range of important areas concerned with the chemical and physical processes by which the solid Earth, the oceans, the atmosphere, and the solar system interact. While his research was broad in scope, it was also characterized by a strong emphasis on meticulous field and laboratory work, and on original and insightful interpretations of the resulting observations.

Weiss, Ray

271

Harmonic radar literature  

NASA Astrophysics Data System (ADS)

A harmonic radar sends on a given frequency f sub o and receives on another frequency usually 3 f sub o. The overtone is generated on joints between the metal parts of the radar target. The generated high harmonic frequency is very weak, which is why this radar has an extremely low range of detection. Natural objects in the target area do not disturb the high frequency harmonics. The radar becomes clutter free. The principals of generating high frequency harmonics cover tunneling, semiconductor and microwave effects. Signal generation is most powerful when f sub o is between 100 and 1000 MHz.

Jansson, B.

1980-07-01

272

Even harmonic lasing  

SciTech Connect

Operation of a free-electron laser at harmonics of the fundamental frequency is explored with the numerical simulation code HELEX. This code includes coupling to the harmonics caused by misalignment of the electrons with the optical beam and coupling due to transverse gradients. Albeit weak, the transverse gradients produce the dominant coupling of the electrons to the even-harmonic light. Even-harmonic lasing occurs in a TEM{sub 0,2m+1}-like mode where the field on axis is zero. As bunching of the electron beam progresses, radiation at the higher odd harmonics is suppressed owing to the absence of higher-order odd-harmonic Fourier components in the bunch. Growth of the even-harmonic power from small signal requires suppression of competing harmonics (including the fundamental) that have higher gain. Lasing at an even harmonic has yet to be experimentally demonstrated in an open resonator (i.e. optical cavity). Strategies to make such an experiment possible are discussed. 9 refs., 5 figs., 1 tab.

Schmitt, M.J.

1991-01-01

273

Dynamic analysis of composite beam subjected to harmonic moving load based on the third-order shear deformation theory  

NASA Astrophysics Data System (ADS)

The response of an infinite Timoshenko beam subjected to a harmonic moving load based on the thirdorder shear deformation theory (TSDT) is studied. The beam is made of laminated composite, and located on a Pasternak viscoelastic foundation. By using the principle of total minimum potential energy, the governing partial differential equations of motion are obtained. The solution is directed to compute the deflection and bending moment distribution along the length of the beam. Also, the effects of two types of composite materials, stiffness and shear layer viscosity coefficients of foundation, velocity and frequency of the moving load over the beam response are studied. In order to demonstrate the accuracy of the present method, the results TSDT are compared with the previously obtained results based on first-order shear deformation theory, with which good agreements are observed.

Rezvanil, Mohammad Javad; Kargarnovin, Mohammad Hossein; Younesian, Davood

2011-12-01

274

High-resolution nanomechanical analysis of suspended electrospun silk fibers with the torsional harmonic atomic force microscope  

PubMed Central

Summary Atomic force microscopes have become indispensable tools for mechanical characterization of nanoscale and submicron structures. However, materials with complex geometries, such as electrospun fiber networks used for tissue scaffolds, still pose challenges due to the influence of tension and bending modulus on the response of the suspended structures. Here we report mechanical measurements on electrospun silk fibers with various treatments that allow discriminating among the different mechanisms that determine the mechanical behavior of these complex structures. In particular we were able to identify the role of tension and boundary conditions (pinned versus clamped) in determining the mechanical response of electrospun silk fibers. Our findings show that high-resolution mechanical imaging with torsional harmonic atomic force microscopy provides a reliable method to investigate the mechanics of materials with complex geometries.

2013-01-01

275

Numerical analysis of broadband second harmonic generation using TIR-QPM in a parabolic profiled isotropic semiconductor slab  

NASA Astrophysics Data System (ADS)

We report second harmonic generation (SHG) with a flat wide bandwidth accompanied by good conversion efficiency in an isotropic semiconductor slab with a parabolic upper profile. The concept of SHG conversion stands on the principle of total internal reflection quasi-phase matching (TIR-QPM). A simulation has been performed using GaAs as the non-linear material, in the fundamental wavelength range of 6.8-10.8 ?m, considering ppp polarization configuration. Optimized simulation results, after considering reflection and absorption losses, show a flatter bandwidth of 642 nm in a 36 mm slab in comparison to a dipped 3 dB bandwidth of 770 nm in an elliptically profiled isotropic slab as well as a steeper bandwidth of 187 nm in a tapered isotropic slab. The present simulation shows an acceptable conversion efficiency of 1.105%.

Banik, Smita; Das, Upama; Deb, Sumita; Saha, Ardhendu

2013-05-01

276

A Global Sensitivity Analysis Methodology for Multi-physics Applications  

SciTech Connect

Experiments are conducted to draw inferences about an entire ensemble based on a selected number of observations. This applies to both physical experiments as well as computer experiments, the latter of which are performed by running the simulation models at different input configurations and analyzing the output responses. Computer experiments are instrumental in enabling model analyses such as uncertainty quantification and sensitivity analysis. This report focuses on a global sensitivity analysis methodology that relies on a divide-and-conquer strategy and uses intelligent computer experiments. The objective is to assess qualitatively and/or quantitatively how the variabilities of simulation output responses can be accounted for by input variabilities. We address global sensitivity analysis in three aspects: methodology, sampling/analysis strategies, and an implementation framework. The methodology consists of three major steps: (1) construct credible input ranges; (2) perform a parameter screening study; and (3) perform a quantitative sensitivity analysis on a reduced set of parameters. Once identified, research effort should be directed to the most sensitive parameters to reduce their uncertainty bounds. This process is repeated with tightened uncertainty bounds for the sensitive parameters until the output uncertainties become acceptable. To accommodate the needs of multi-physics application, this methodology should be recursively applied to individual physics modules. The methodology is also distinguished by an efficient technique for computing parameter interactions. Details for each step will be given using simple examples. Numerical results on large scale multi-physics applications will be available in another report. Computational techniques targeted for this methodology have been implemented in a software package called PSUADE.

Tong, C H; Graziani, F R

2007-02-02

277

Covariant harmonic oscillators and coupled harmonic oscillators  

NASA Technical Reports Server (NTRS)

It is shown that the system of two coupled harmonic oscillators shares the basic symmetry properties with the covariant harmonic oscillator formalism which provides a concise description of the basic features of relativistic hadronic features observed in high-energy laboratories. It is shown also that the coupled oscillator system has the SL(4,r) symmetry in classical mechanics, while the present formulation of quantum mechanics can accommodate only the Sp(4,r) portion of the SL(4,r) symmetry. The possible role of the SL(4,r) symmetry in quantum mechanics is discussed.

Han, Daesoo; Kim, Young S.; Noz, Marilyn E.

1995-01-01

278

You're OK and so is physics: The use of transactional analysis with inquiry methods in physics teaching  

NSDL National Science Digital Library

The authors examined physics learning experiences and found they had to consider not only the physics content, but also the student's self-image. They describe transactional analysis in the context of a course combining an inquiry approach to physics with elementary school science teaching methods.

Fuller, Robert G.; Sims, Ward L.

2012-05-15

279

QA/QC requirements for physical properties sampling and analysis  

SciTech Connect

This report presents results of an assessment of the available information concerning US Environmental Protection Agency (EPA) quality assurance/quality control (QA/QC) requirements and guidance applicable to sampling, handling, and analyzing physical parameter samples at Comprehensive Environmental Restoration, Compensation, and Liability Act (CERCLA) investigation sites. Geotechnical testing laboratories measure the following physical properties of soil and sediment samples collected during CERCLA remedial investigations (RI) at the Hanford Site: moisture content, grain size by sieve, grain size by hydrometer, specific gravity, bulk density/porosity, saturated hydraulic conductivity, moisture retention, unsaturated hydraulic conductivity, and permeability of rocks by flowing air. Geotechnical testing laboratories also measure the following chemical parameters of soil and sediment samples collected during Hanford Site CERCLA RI: calcium carbonate and saturated column leach testing. Physical parameter data are used for (1) characterization of vadose and saturated zone geology and hydrogeology, (2) selection of monitoring well screen sizes, (3) to support modeling and analysis of the vadose and saturated zones, and (4) for engineering design. The objectives of this report are to determine the QA/QC levels accepted in the EPA Region 10 for the sampling, handling, and analysis of soil samples for physical parameters during CERCLA RI.

Innis, B.E.

1993-07-21

280

Harmonic radar literature  

Microsoft Academic Search

A harmonic radar sends on a given frequency f sub o and receives on another frequency usually 3 f sub o. The overtone is generated on joints between the metal parts of the radar target. The generated high harmonic frequency is very weak, which is why this radar has an extremely low range of detection. Natural objects in the target

B. Jansson

1980-01-01

281

Singular spin harmonics  

Microsoft Academic Search

The definition of the spin-weighted spherical harmonics, sYlm, is extended so that all integral spin weights, s, are allowed. We then discuss a set of spin-weighted functions, sZlm, which are analogous to the spherical harmonics of the second kind.

G. J. Weir

1979-01-01

282

Harmonic Scalpel® Hemorrhoidectomy  

Microsoft Academic Search

PURPOSE: The aim of this study was to evaluate the incidence of postoperative complications after Harmonic Scalpel® hemorrhoidectomy and to identify any predisposing factors leading to postoperative complications. METHODS: Five hundred consecutive cases of Harmonic Scalpel® hemorrhoidectomy were studied in a prospective manner. Postoperative complications were recorded, and any predisposing factors were evaluated. RESULTS: Three hundred fifty-five patients (71 percent)

David N. Armstrong; Charles Frankum; Marion E. Schertzer; Wayne L. Ambroze; Guy R. Orangio

2002-01-01

283

Fast Polar Harmonic Transforms  

Microsoft Academic Search

Polar Harmonic Transform (PHT) is termed to represent a set of transforms those kernels are basic waves and harmonic in nature. PHTs consist of Polar Complex Exponential Transform (PCET), Polar Cosine Transform (PCT) and Polar Sine Transform (PST). They are proposed to represent invariant image patterns for two dimensional image retrieval and pattern recognition tasks. They are demonstrated to show

Zhuo Yang; Sei-ichiro Kamata

2010-01-01

284

Relativistic harmonic oscillator revisited  

SciTech Connect

The familiar Fock space commonly used to describe the relativistic harmonic oscillator, for example, as part of string theory, is insufficient to describe all the states of the relativistic oscillator. We find that there are three different vacua leading to three disconnected Fock sectors, all constructed with the same creation-annihilation operators. These have different spacetime geometric properties as well as different algebraic symmetry properties or different quantum numbers. Two of these Fock spaces include negative norm ghosts (as in string theory), while the third one is completely free of ghosts. We discuss a gauge symmetry in a worldline theory approach that supplies appropriate constraints to remove all the ghosts from all Fock sectors of the single oscillator. The resulting ghost-free quantum spectrum in d+1 dimensions is then classified in unitary representations of the Lorentz group SO(d,1). Moreover, all states of the single oscillator put together make up a single infinite dimensional unitary representation of a hidden global symmetry SU(d,1), whose Casimir eigenvalues are computed. Possible applications of these new results in string theory and other areas of physics and mathematics are briefly mentioned.

Bars, Itzhak [Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089-2535 (United States)

2009-02-15

285

Physical interpretation and sensitivity analysis of the TOPMODEL  

NASA Astrophysics Data System (ADS)

The TOPMODEL is a variable contributing area conceptual model in which the predominant factors determining the formation of runoff are represented by the topography of the basin and a negative exponential law linking the transmissivity of the soil with the distance to the saturated zone below the ground level. Although conceptual, this model is frequently described as a 'physically based model' in the sense that its parameters can be measured directly in situ. In line with the analysis of various conceptual rainfall-runoff models conducted by Franchini and Pacciani ( J. Hydrol., 122: 161-219, 1991), a detailed analysis of the TOPMODEL is performed to arrive at a closer understanding of the correspondence of the assumptions underpinning the model with the physical reality and, in particular, the role that topographic information (expressed by the topographic index curve) and the nature of the soil (expressed by saturated hydraulic conductivity and its decay with soil depth), have within the model itself. Also investigated is the extent to which the model parameters actually reflect the physical properties to which they refer and how far their values offset the inevitable schematisation of the model. The various applications to real situations include the Sieve basin (river Arno tributary), which was used for the comparison of conceptual rainfall-runoff models described in the above-mentioned study by Franchini and Paccini. This allows that analysis to be extended to the TOPMODEL.

Franchini, Marco; Wendling, Jacques; Obled, Charles; Todini, Ezio

1996-02-01

286

Hyperspherical Harmonic Formalism for Tetraquarks  

NASA Astrophysics Data System (ADS)

We present a generalization of the hyperspherical harmonic formalism to study systems made of quarks and antiquarks of the same flavor. This generalization is based on the symmetrization of the N-body wave function with respect to the symmetric group using the Barnea and Novoselsky algorithm. Our analysis shows that four-quark systems with non-exotic 2++ quantum numbers may be bound independently of the quark mass. 0+- and 1+- states become attractive only for larger quarks masses.

Vijande, J.; Valcarce, A.; Barnea, N.

287

Physics analysis of the gang partial rod drive event  

SciTech Connect

During the routine positioning of partial-length control rods in Gang 3 on the afternoon of Monday, July 27, 1992, the partial-length rods continued to drive into the reactor even after the operator released the controlling toggle switch. In response to this occurrence, the Safety Analysis and Engineering Services Group (SAEG) requested that the Applied Physics Group (APG) analyze the gang partial rod drive event. Although similar accident scenarios were considered in analysis for Chapter 15 of the Safety Analysis Report (SAR), APG and SAEG conferred and agreed that this particular type of gang partial-length rod motion event was not included in the SAR. This report details this analysis.

Boman, C.; Frost, R.L.

1992-08-01

288

Meta-Analysis of Workplace Physical Activity Interventions  

PubMed Central

Context Most adults do not achieve adequate physical activity. Despite the potential benefits of worksite health promotion, no previous comprehensive meta-analysis has summarized health and physical activity behavior outcomes from these programs. This comprehensive meta-analysis integrated the extant wide range of worksite physical activity intervention research. Evidence acquisition Extensive searching located published and unpublished intervention studies reported from 1969 through 2007. Results were coded from primary studies. Random-effects meta-analytic procedures, including moderator analyses, were completed in 2008. Evidence synthesis Effects on most variables were substantially heterogeneous because diverse studies were included. Standardized mean difference (d) effect sizes were synthesized across approximately 38,231 subjects. Significantly positive effects were observed for physical activity behavior (0.21), fitness (0.57), lipids (0.13), anthropometric measures (0.08), work attendance (0.19), and job stress (0.33). The significant effect size for diabetes risk (0.98) is more tentative given small sample sizes. Significant heterogeneity documents intervention effects varied across studies. The mean effect size for fitness corresponds to a difference between treatment minus control subjects' means on V02max of 3.5 mL/kg/min; for lipids, ?0.2 on total cholesterol:HDL; and for diabetes risk, ?12.6 mg/dL on fasting glucose. Conclusions These findings document that some workplace physical activity interventions can improve both health and important worksite outcomes. Effects were variable for most outcomes, reflecting the diversity of primary studies. Future primary research should compare interventions to confirm causal relationships and further explore heterogeneity.

Conn, Vicki S.; Hafdahl, Adam R.; Cooper, Pamela S.; Brown, Lori M.; Lusk, Sally L.

2009-01-01

289

An algorithm of the harmonics on traction power system of the electrified railway  

Microsoft Academic Search

The authors explore harmonic calculations for Chinese electrified railway systems. One of the branches of the electrified railway power system in operation was emulated and calculated with special purpose software for analyzing harmonic currents. The multiple harmonic sources and the asymmetry of the system make the harmonic analysis complicated. The three-phase power system is converted into a single-phase network with

Pan Yinxuan; Sun Shugin; Li Chunhua

1990-01-01

290

New breathing functions for the transverse breathing crack of the cracked rotor system: Approach for critical and subcritical harmonic analysis  

NASA Astrophysics Data System (ADS)

The actual breathing mechanism of the transverse breathing crack in the cracked rotor system that appears due to the shaft weight is addressed here. As a result, the correct time-varying area moments of inertia for the cracked element cross-section during shaft rotation are also determined. Hence, two new breathing functions are identified to represent the actual breathing effect on the cracked element stiffness matrix. The new breathing functions are used in formulating the time-varying finite element stiffness matrix of the cracked element. The finite element equations of motion are then formulated for the cracked rotor system and solved via harmonic balance method for response, whirl orbits and the shift in the critical and subcritical speeds. The analytical results of this approach are compared with some previously published results obtained using approximate formulas for the breathing mechanism. The comparison shows that the previously used breathing function is a weak model for the breathing mechanism in the cracked rotor even for small crack depths. The new breathing functions give more accurate results for the dynamic behavior of the cracked rotor system for a wide range of the crack depths. The current approach is found to be efficient for crack detection since the critical and subcritical shaft speeds, the unique vibration signature in the neighborhood of the subcritical speeds and the sensitivity to the unbalance force direction all together can be utilized to detect the breathing crack before further damage occurs.

Al-Shudeifat, Mohammad A.; Butcher, Eric A.

2011-01-01

291

Second International Workshop on Harmonic Oscillators  

NASA Technical Reports Server (NTRS)

The Second International Workshop on Harmonic Oscillators was held at the Hotel Hacienda Cocoyoc from March 23 to 25, 1994. The Workshop gathered 67 participants; there were 10 invited lecturers, 30 plenary oral presentations, 15 posters, and plenty of discussion divided into the five sessions of this volume. The Organizing Committee was asked by the chairman of several Mexican funding agencies what exactly was meant by harmonic oscillators, and for what purpose the new research could be useful. Harmonic oscillators - as we explained - is a code name for a family of mathematical models based on the theory of Lie algebras and groups, with applications in a growing range of physical theories and technologies: molecular, atomic, nuclear and particle physics; quantum optics and communication theory.

Han, Daesoo (editor); Wolf, Kurt Bernardo (editor)

1995-01-01

292

Modeling Identification, and Control of Harmonic Drives for Automotive Applications  

Microsoft Academic Search

This paper reports the modeling, identification, and control of harmonic drives in a novel configuration where all its shafts are allowed to move. This makes possible to solve a control problem where one applies two actuators in order to carry out simultaneous position and torque control on two different axes of the harmonic drive. Physical parameters used during the MIMO

L. Lemmer; B. Kiss; I. Janosi

2006-01-01

293

Positioning Ideas: Creating and Relating Physics Identities Through Video Analysis  

NASA Astrophysics Data System (ADS)

Prior research has documented that analyzing video of children learning science aids pre-service teachers in developing physics knowledge and deepens their understanding of the learning process. Research on video analysis in teacher education suggests that the primary value of such tasks comes not from watching the video, but from the subsequent discussions. We questioned whether similar advantages would be evident when participants watched and analyzed video clips via online threaded discussions. We found that participants used the video clips as a mediating tool to position their own current ideas about physics topics with respect to their prior understandings as well as to ideas articulated by the students in the video clips. We discuss the study findings and affordances and limitations of online discussion formats.

Harlow, Danielle Boyd; Swanson, Lauren H.

2009-11-01

294

Positioning Ideas: Creating and Relating Physics Identities Through Video Analysis  

NSDL National Science Digital Library

Prior research has documented that analyzing video of children learning science aids pre-service teachers in developing physics knowledge and deepens their understanding of the learning process. Research on video analysis in teacher education suggests that the primary value of such tasks comes not from watching the video, but from the subsequent discussions. We questioned whether similar advantages would be evident when participants watched and analyzed video clips via online threaded discussions. We found that participants used the video clips as a mediating tool to position their own current ideas about physics topics with respect to their prior understandings as well as to ideas articulated by the students in the video clips. We discuss the study findings and affordances and limitations of online discussion formats.

Harlow, Danielle; Swanson, Lauren

2010-01-19

295

Relationship between monopole harmonics and spin-weighted spherical harmonics  

SciTech Connect

We compare two independent generalizations of the usual spherical harmonics, namely monopole harmonics and spin-weighted spherical harmonics, and make precise the sense in which they can be considered to be the same. By analogy with the spin-gauge language, raising and lowering operators for the monopole index of the monopole harmonics can immediately be written down.

Dray, T.

1985-05-01

296

Harmonic oscillator interacting with conical singularities  

NASA Astrophysics Data System (ADS)

We study the quantum dynamics of a particle interacting harmonically with conical singularities that physically correspond to either a cosmic string, a global monopole, a magnetic flux string or a screw dislocation, by solving the corresponding Schrödinger equations. Exact expressions for the energy eigenfunctions and eigenvalues are found.

Furtado, Cláudio; Moraes, Fernando

2000-08-01

297

Computational particle physics for event generators and data analysis  

NASA Astrophysics Data System (ADS)

High-energy physics data analysis relies heavily on the comparison between experimental and simulated data as stressed lately by the Higgs search at LHC and the recent identification of a Higgs-like new boson. The first link in the full simulation chain is the event generation both for background and for expected signals. Nowadays event generators are based on the automatic computation of matrix element or amplitude for each process of interest. Moreover, recent analysis techniques based on the matrix element likelihood method assign probabilities for every event to belong to any of a given set of possible processes. This method originally used for the top mass measurement, although computing intensive, has shown its efficiency at LHC to extract the new boson signal from the background. Serving both needs, the automatic calculation of matrix element is therefore more than ever of prime importance for particle physics. Initiated in the 80's, the techniques have matured for the lowest order calculations (tree-level), but become complex and CPU time consuming when higher order calculations involving loop diagrams are necessary like for QCD processes at LHC. New calculation techniques for next-to-leading order (NLO) have surfaced making possible the generation of processes with many final state particles (up to 6). If NLO calculations are in many cases under control, although not yet fully automatic, even higher precision calculations involving processes at 2-loops or more remain a big challenge. After a short introduction to particle physics and to the related theoretical framework, we will review some of the computing techniques that have been developed to make these calculations automatic. The main available packages and some of the most important applications for simulation and data analysis, in particular at LHC will also be summarized (see CCP2012 slides [1]).

Perret-Gallix, Denis

2013-08-01

298

HARMONIC OSCILLATOR PROPAGATOR  

Microsoft Academic Search

We show how the pre-exponential factor of the Feynman propagator for the harmonic oscillator can be computed by the generalized ?-function method. Besides, we establish a direct equivalence between this method and Schwinger's propertime method.

F. A. Barone; C. Farina

299

Simple Harmonic Motion  

NSDL National Science Digital Library

This simulation offers two examples of simple harmonic motion, a mass on a spring and a simple pendulum. The applet allows you to adjust variables and observe the effects these changes have on the movement of the systems.

Pfaff, Raman

2008-07-15

300

Harmonically Excited Orbital Variations.  

National Technical Information Service (NTIS)

Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In...

T. Morgan

1985-01-01

301

Management of the Space Physics Analysis Network (SPAN)  

NASA Technical Reports Server (NTRS)

Here, the purpose is to define the operational management structure and to delineate the responsibilities of key Space Physics Analysis Network (SPAN) individuals. The management structure must take into account the large NASA and ESA science research community by giving them a major voice in the operation of the system. Appropriate NASA and ESA interfaces must be provided so that there will be adequate communications facilities available when needed. Responsibilities are delineated for the Advisory Committee, the Steering Committee, the Project Scientist, the Project Manager, the SPAN Security Manager, the Internetwork Manager, the Network Operations Manager, the Remote Site Manager, and others.

Green, James L.; Thomas, Valerie L.; Butler, Todd F.; Peters, David J.; Sisson, Patricia L.

1990-01-01

302

Multi-Physics Analysis of the Fermilab Booster RF Cavity  

SciTech Connect

After about 40 years of operation the RF accelerating cavities in Fermilab Booster need an upgrade to improve their reliability and to increase the repetition rate in order to support a future experimental program. An increase in the repetition rate from 7 to 15 Hz entails increasing the power dissipation in the RF cavities, their ferrite loaded tuners, and HOM dampers. The increased duty factor requires careful modelling for the RF heating effects in the cavity. A multi-physic analysis investigating both the RF and thermal properties of Booster cavity under various operating conditions is presented in this paper.

Awida, M.; Reid, J.; Yakovlev, V.; Lebedev, V.; Khabiboulline, T.; Champion, M.; /Fermilab

2012-05-14

303

Harmonic mappings onto stars  

NASA Astrophysics Data System (ADS)

A general version of the Radó-Kneser-Choquet theorem implies that a piecewise constant sense-preserving mapping of the unit circle onto the vertices of a convex polygon extends to a univalent harmonic mapping of the unit disk onto the polygonal domain. This paper discusses similarly generated harmonic mappings of the disk onto nonconvex polygonal regions in the shape of regular stars. Calculation of the Blaschke product dilatation allows a determination of the exact range of parameters that produce univalent mappings.

Duren, Peter; McDougall, Jane; Schaubroeck, Lisbeth

2005-07-01

304

The Local Stellar Velocity Field via Vector Spherical Harmonics  

NASA Technical Reports Server (NTRS)

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 corrected 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. The Oort parameters determined by a straightforward least-squares adjustment in vector spherical harmonics are A=14.0 +/- 1.4, B=13.1 +/- 1.2, K=1.1 +/- 1.8, and C=2.9 +/- 1.4 km s(exp -1) kpc(exp -1). The physical meaning and the implications of these parameters are discussed in the framework of a general linear model of the velocity field. We find a few statistically significant higher degree harmonic terms that do not correspond to any parameters in the classical linear model. One of them, a third-degree electric harmonic, is tentatively explained as the response to a negative linear gradient of rotation velocity with distance from the Galactic plane, which we estimate at approximately -20 km s(exp -1) kpc(exp -1). A similar vertical gradient of rotation velocity has been detected for more distant stars representing the thick disk (z greater than 1 kpc), but here we surmise its existence in the thin disk at z less than 200 pc. The most unexpected and unexplained term within the Ogorodnikov-Milne model is the first-degree magnetic harmonic, representing a rigid rotation of the stellar field about the axis -Y pointing opposite to the direction of rotation. This harmonic comes out with a statistically robust coefficient of 6.2 +/- 0.9 km s(exp -1) kpc(exp -1) and is also present in the velocity field of more distant stars. The ensuing upward vertical motion of stars in the general direction of the Galactic center and the downward motion in the anticenter direction are opposite to the vector field expected from the stationary Galactic warp model.

Markarov, V. V.; Murphy, D. W.

2007-01-01

305

The Local Stellar Velocity Field via Vector Spherical Harmonics  

NASA Astrophysics Data System (ADS)

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 (VX,VY,VZ)=(10.5,18.5,7.3)+/-0.1 km s-1 not corrected 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 (VX,VY,VZ)=(9.9,15.6,6.9)+/-0.2 km s-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. The Oort parameters determined by a straightforward least-squares adjustment in vector spherical harmonics are A=14.0+/-1.4, B=-13.1+/-1.2, K=1.1+/-1.8, and C=-2.9+/-1.4 km s-1 kpc-1. The physical meaning and the implications of these parameters are discussed in the framework of a general linear model of the velocity field. We find a few statistically significant higher degree harmonic terms that do not correspond to any parameters in the classical linear model. One of them, a third-degree electric harmonic, is tentatively explained as the response to a negative linear gradient of rotation velocity with distance from the Galactic plane, which we estimate at ~-20 km s-1 kpc-1. A similar vertical gradient of rotation velocity has been detected for more distant stars representing the thick disk (z>1 kpc), but here we surmise its existence in the thin disk at z<200 pc. The most unexpected and unexplained term within the Ogorodnikov-Milne model is the first-degree magnetic harmonic, representing a rigid rotation of the stellar field about the axis -Y pointing opposite to the direction of rotation. This harmonic comes out with a statistically robust coefficient of 6.2+/-0.9 km s-1 kpc-1 and is also present in the velocity field of more distant stars. The ensuing upward vertical motion of stars in the general direction of the Galactic center and the downward motion in the anticenter direction are opposite to the vector field expected from the stationary Galactic warp model.

Makarov, V. V.; Murphy, D. W.

2007-07-01

306

Analysis of the physical mechanisms behind the Weddell Sea Anomaly using a physics-based data assimilation model  

NASA Astrophysics Data System (ADS)

The Weddell Sea Anomaly (WSA) is a mid-latitude F region ionosphere phenomena taking place over the regions west of the Antarctic Peninsula. It is most prominent during local summer, is characterized by larger electron densities at night than at noon and completely disappears during winter. Though the WSA has been known for several decades, its generation mechanism is not fully understood and its modeling remains a challenge. In the current study the GPS radio occultation measurements from the six FORMOSAT-3/COSMIC satellites combined with a physics-based data assimilation model of the ionosphere were used to understand the physical mechanism behind the WSA generation. The data assimilation model is the Global Assimilation of Ionospheric Measurements Full-Physics model (GAIM-FP) that covers the altitude range from 90 to 20,000 km, includes six ion species (NO+, O2+, N2+, O+, H+, He+), is based on the International Geomagnetic Reference Field (IGRF), and allows for interhemispheric flow. The model uses an Ensemble Kalman filter approach and provides the 3-dimensional electron density distribution throughout the ionosphere and information about the physical drivers, including the magnetic meridional wind, neutral composition and electric fields. The geographic zonal and meridional winds were inferred from the magnetic meridional wind based on a decoupling procedure that considers the longitudinal variation of magnetic declination and wind decomposition into zonal harmonics. The separate wind components were used to study their effects on the generation of the anomaly. In addition the production, loss and transport processes were separately analyzed to establish the relative role of the various physical processes that cause the WSA.

Lomidze, L.; Scherliess, L.

2013-01-01

307

Cost and performance analysis of physical security systems  

SciTech Connect

CPA - Cost and Performance Analysis - is a prototype integration of existing PC-based cost and performance analysis tools: ACEIT (Automated Cost Estimating Integrated Tools) and ASSESS (Analytic System and Software for Evaluating Safeguards and Security). ACE is an existing DOD PC-based tool that supports cost analysis over the full life cycle of a system; that is, the cost to procure, operate, maintain and retire the system and all of its components. ASSESS is an existing DOE PC-based tool for analysis of performance of physical protection systems. Through CPA, the cost and performance data are collected into Excel workbooks, making the data readily available to analysts and decision makers in both tabular and graphical formats and at both the system and subsystem levels. The structure of the cost spreadsheets incorporates an activity-based approach to cost estimation. Activity-based costing (ABC) is an accounting philosophy used by industry to trace direct and indirect costs to the products or services of a business unit. By tracing costs through security sensors and procedures and then mapping the contributions of the various sensors and procedures to system effectiveness, the CPA architecture can provide security managers with information critical for both operational and strategic decisions. The architecture, features and applications of the CPA prototype are presented. 5 refs., 3 figs.

Hicks, M.J. [Sandia National Lab., Albuquerque, NM (United States); Yates, D.; Jago, W.H. [Tecolote Research, Inc., Santa Barbara, CA (United States)] [and others

1997-06-01

308

Microstructural characterization in plates using guided wave third harmonic generation  

NASA Astrophysics Data System (ADS)

Presently, good understanding of second harmonic generation in a weakly nonlinear plate has been obtained, yet the limited number of primary excitations constrains the use of second harmonics in field measurements. The cumulative characteristics of third harmonic generation in a cubic nonlinear plate has been investigated. The power flux analysis shows that primary wave fields are capable of generating a cumulative third harmonic that is of the same nature. Further synchronism analysis shows that the primary shear-horizontal modes are holo-internal-resonant with third harmonic fields, which will be advantageous in experimental measurements. A nonlinear finite element simulation confirms that the primary SH1 mode generates a cumulative sh3 third harmonic mode.

Liu, Yang; Lissenden, Cliff J.; Rose, Joseph L.

2014-02-01

309

Identification and tracking of harmonic sources in a power system using a Kalman filter  

SciTech Connect

In this paper, two problems have been addressed on harmonic sources identification: the optimal locations of a limited number of harmonic meters and the optimal dynamic estimates of harmonic source locations and their injections in unbalanced three-phase power systems. A Kalman filtering is used to attack these problems. System error covariance analysis by the Kalman filter associated with a harmonic injection estimate determines the optimal arrangement of limited harmonic meters. Based on the optimally-arranged harmonic metering locations, the Kalman filter then yields the optimal dynamic estimates of harmonic injections with a few noisy harmonic measurements. The method is dynamic and has the capability of identifying, analyzing and tracking each harmonic injection at all buses in unbalanced three-phase power systems. Actual recorded harmonic measurements and simulated data in a power distribution system are provided to prove the efficiency of this approach.

Ma, H. [Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Electrical and Computer Engineering; Girgis, A.A. [Clemson Univ., SC (United States). Dept. of Electrical and Computer Engineering

1996-07-01

310

Optical harmonic generator  

DOEpatents

A pair of uniaxial birefringent crystal elements are fixed together to form a serially arranged, integral assembly which, alternatively, provides either a linearly or elliptically polarized second-harmonic output wave or a linearly polarized third-harmonic output wave. The extraordinary or e directions of the crystal elements are oriented in the integral assembly to be in quadrature (90/sup 0/). For a second-harmonic generation in the Type-II-Type-II angle tuned case, the input fundamental wave has equal amplitude o and e components. For a third-harmonic generation, the input fundamental wave has o and e components whose amplitudes are in a ratio of 2:1 (o:e reference first crystal). In the typical case of a linearly polarized input fundamental wave this can be accomplished by simply rotating the crystal assembly about the input beam direction by 10/sup 0/. For both second and third harmonic generation input precise phase-matching is achieved by tilting the crystal assembly about its two sensitive axeses (o).

Summers, M.A.; Eimerl, D.; Boyd, R.D.

1982-06-10

311

Optical harmonic generator  

DOEpatents

A pair of uniaxial birefringent crystal elements are fixed together to form a serially arranged, integral assembly which, alternatively, provides either a linearly or elliptically polarized second-harmonic output wave or a linearly polarized third-harmonic output wave. The "extraordinary" or "e" directions of the crystal elements are oriented in the integral assembly to be in quadrature (90.degree.). For a second-harmonic generation in the Type-II-Type-II angle tuned case, the input fundamental wave has equal amplitude "o" and "e" components. For a third-harmonic generation, the input fundamental wave has "o" and "e" components whose amplitudes are in a ratio of 2:1 ("o":"e" reference first crystal). In the typical case of a linearly polarized input fundamental wave this can be accomplished by simply rotating the crystal assembly about the input beam direction by 10.degree.. For both second and third harmonic generation input precise phase-matching is achieved by tilting the crystal assembly about its two sensitive axes ("o").

Summers, Mark A. (Livermore, CA); Eimerl, David (Pleasanton, CA); Boyd, Robert D. (Livermore, CA)

1985-01-01

312

A Utopian View of Space Plasma Physics Data Analysis (Invited)  

NASA Astrophysics Data System (ADS)

In an ideal space physics plasma data environment, I would go to the internet, enter names and types of data sets that I need, find them immediately via a google-like search, download them into a folder, and then use my all-purpose platform-independent software to immediately begin plotting, analyzing, and combining data sets from multiple sources, instruments, and spacecraft without ever writing any software myself or even looking inside the files. In order for this to happen, the data sets would have to be in readily recognizable standardized formats, described in sufficient detail to enable rapid discovery, and accompanied by metadata enabling the software to work. The display and analysis tools would have to include the full range of features needed for data visualization, including the construction of parameters or plots combining observations from multiple sources.

Sibeck, D. G.

2010-12-01

313

Theoretical analysis of the TE mode Cerenkov type second harmonic generation in ion-implanted X-cut lithium niobate channel waveguides  

NASA Astrophysics Data System (ADS)

Optical second harmonic generation (SHG) in the form of Cerenkov radiation from ion-implanted lithium niobate (LiNbO 3) channel waveguides is analyzed by directly resolving the wave equations. Useful formula of the SHG efficiency is derived and expressed in terms of waveguide parameters. Numerical examples are plotted for LiNbO 3 crystals. The results enable the optimization of waveguide design for efficient second harmonic generation in the Cerenkov configuration.

Du, Guolong; Li, Guiqiu; Zhao, Shengzhi; Li, Xin; Yu, Zhiyuan

2012-06-01

314

Harmonization of uncertainties of X-ray fluorescence data for PM2.5 air filter analysis.  

PubMed

The U.S. Environmental Protection Agency (EPA)'s PM2.5 Chemical Speciation Network (CSN) and the Interagency Monitoring of Protected Visual Environments (IMPROVE) network use X-ray fluorescence (XRF) analysis to quantify trace elements in samples of fine particles less than 2.5 microns in aerodynamic diameter (PM2.5). Methods for calculating uncertainty values for XRF results vary considerably among laboratories and instrument makes and models. To support certain types of modeling and data analysis, uncertainty estimates are required that are consistent within and between monitoring programs, and that are independent of the laboratories that performed the analyses and the analytical instrumentation used. The goal of this work was to develop a consensus model for uncertainties associated with XRF analysis of PM2.5 filter samples. The following important components of uncertainty are included in the model described herein: variability in peak area, calibration, field sampling, and attenuation of X-ray intensity for light elements. This paper includes a detailed analysis of how attenuation uncertainties for light elements are derived. For the remaining uncertainty components included in the model, an approach and recommendations are presented to ensure that laboratories performing this type of analysis can use similar equations and parameterizations. By applying this uniform approach, it is illustrated how the uncertainties reported by the CSN and IMPROVE network laboratories can be brought into very good agreement. The proposed method is best applied at the time of data generation, but retrospective estimation of uncertainties in existing data-sets is also possible. This paper serves to document the equations used for calculating the uncertainties in speciated PM2.5 data currently being posted on EPA's Air Quality System database for the PM2.5 CSN program. PMID:20222531

Gutknecht, William; Flanagan, James; McWilliams, Andrea; Jayanty, R K M; Kellogg, Robert; Rice, Joann; Duda, Paul; Sarver, Richard H

2010-02-01

315

Characterization of collagen fibers by means of texture analysis of second harmonic generation images using orientation-dependent gray level co-occurrence matrix method  

NASA Astrophysics Data System (ADS)

Collagen is the most prominent protein in the human body, making up 30% of the total protein content. Quantitative studies have shown structural differences between collagen fibers of the normal and diseased tissues, due to the remodeling of the extracellular matrix during the pathological process. The dominant orientation, which is an important characteristic of collagen fibers, has not been taken into consideration for quantitative collagen analysis. Based on the conventional gray level co-occurrence matrix (GLCM) method, the authors proposed the orientation-dependent GLCM (OD-GLCM) method by estimating the dominant orientation of collagen fibers. The authors validated the utility of the OD-GLCM method on second harmonic generation (SHG) microscopic images of tendons from rats with different ages. Compared with conventional GLCM method, the authors' method has not only improved the discrimination between different tissues but also provided additional texture information of the orderliness of collagen fibers and the fiber size. The OD-GLCM method was further applied to the differentiation of the preliminary SHG images of normal and cancerous human pancreatic tissues. The combination of SHG microscopy and the OD-GLCM method might be helpful for the evaluation of diseases marked with abnormal collagen morphology.

Hu, Wenyan; Li, Hui; Wang, Chunyou; Gou, Shanmiao; Fu, Ling

2012-02-01

316

The time-dependent quantum harmonic oscillator revisited: Applications to quantum field theory  

NASA Astrophysics Data System (ADS)

In this article, we formulate the study of the unitary time evolution of systems consisting of an infinite number of uncoupled time-dependent harmonic oscillators in mathematically rigorous terms. We base this analysis on the theory of a single one-dimensional time-dependent oscillator, for which we first summarize some basic results concerning the unitary implementability of the dynamics. This is done by employing techniques different from those used so far to derive the Feynman propagator. In particular, we calculate the transition amplitudes for the usual harmonic oscillator eigenstates and define suitable semiclassical states for some physically relevant models. We then explore the possible extension of this study to infinite dimensional dynamical systems. Specifically, we construct Schrödinger functional representations in terms of appropriate probability spaces, analyze the unitarity of the time evolution, and probe the existence of semiclassical states for a wide range of physical systems, particularly, the well-known Minkowskian free scalar fields and Gowdy cosmological models.

Vergel, Daniel Gómez; Villaseñor, Eduardo J. S.

2009-06-01

317

Multitone harmonic radar  

NASA Astrophysics Data System (ADS)

Nonlinear radar exploits the electronic response from a target whose reflected frequencies are different from those transmitted. Reception of frequencies that are not part of the transmitted probe distinguishes the received signal from a linear return produced by clutter and indicates the presence of electronics. Presented in this paper is a type of nonlinear radar that transmits multiple frequencies and listens for a harmonic of these frequencies as well as other frequencies near that harmonic. A laboratory test-bed has been constructed to demonstrate the multitone radar concept. Measurements of nonlinear responses from RF devices probed by multiple tones are reported.

Mazzaro, Gregory J.; Martone, Anthony F.

2013-05-01

318

Chromatic second harmonic imaging.  

PubMed

We report a non-axial-scanning second harmonic imaging technique, in which the chromatic aberration of a Fresnel lens is exploited to focus different wavelengths of a fundamental beam into different axial positions to effectively realize axial scanning. Since the second harmonic signals at different axial positions are generated by different fundamental wavelengths and hence accordingly have different center wavelengths, they can be resolved and detected in parallel by using a spectrometer without axial mechanical scanning. We have demonstrated a system capable of achieving about 8 ?m effective axial scanning range. Proof-of-concept imaging results are also presented. PMID:21164728

Yang, Chuan; Shi, Kebin; Li, Haifeng; Xu, Qian; Gopalan, Venkatraman; Liu, Zhiwen

2010-11-01

319

Comparative analysis of the high-order harmonic generation in the laser ablation plasmas prepared on the surfaces of complex and atomic targets  

SciTech Connect

We analyzed high-order harmonic generation from the plasma plumes prepared on the surfaces of complex targets. The studies of In-Ag targets showed that the characteristics of the high-order harmonics from the double-target plume were the same as those from the single-target plasmas. For the chromium-tellurium plasma, the enhancements of the 29th and 27th harmonics were obtained, thus indicating the appearance of the enhancement properties from both components of the double-target plasma. These comparative studies also showed higher enhancement of a single harmonic in the case of atomic plasma (Sb) with regard to the molecular one (InSb). The additional component can only decrease the enhancement factor of the medium, due to the change of the oscillator strength and spectral distribution of the transitions involved in the resonance enhancement of the specific harmonic order. The theoretical calculations have shown the enhancement of specific harmonics for the Sb, Te, and Cr plasmas in the double-target configurations.

Ganeev, R. A. [Scientific Association Akadempribor, Academy of Sciences of Uzbekistan, Akademgorodok, Tashkent 100125 (Uzbekistan); Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Milosevic, D. B. [Faculty of Science, University of Sarajevo, Zmaja od Bosne 35, 71000 Sarajevo (Bosnia and Herzegowina); Max-Born-Institut, Max-Born-Strasse 2a, 12489 Berlin (Germany)

2008-07-15

320

A harmonic-free AC to AC power supply using DC current link: steady-state analysis and design  

Microsoft Academic Search

This paper is concerned with the steady-state analysis and design of an sinusoidal input\\/output AC to AC power supply with DC current link. Despite many advantages of such a structure, its application in fixed frequency power supplies has received very little attention in the literature. Steady-state modeling of the system is carried out. Unity power factor operation of the system

Hamid R Karshenas; S. B. Dewan

1998-01-01

321

Data intensive high energy physics analysis in a distributed cloud  

NASA Astrophysics Data System (ADS)

We show that distributed Infrastructure-as-a-Service (IaaS) compute clouds can be effectively used for the analysis of high energy physics data. We have designed a distributed cloud system that works with any application using large input data sets requiring a high throughput computing environment. The system uses IaaS-enabled science and commercial clusters in Canada and the United States. We describe the process in which a user prepares an analysis virtual machine (VM) and submits batch jobs to a central scheduler. The system boots the user-specific VM on one of the IaaS clouds, runs the jobs and returns the output to the user. The user application accesses a central database for calibration data during the execution of the application. Similarly, the data is located in a central location and streamed by the running application. The system can easily run one hundred simultaneous jobs in an efficient manner and should scale to many hundreds and possibly thousands of user jobs.

Charbonneau, A.; Agarwal, A.; Anderson, M.; Armstrong, P.; Fransham, K.; Gable, I.; Harris, D.; Impey, R.; Leavett-Brown, C.; Paterson, M.; Podaima, W.; Sobie, R. J.; Vliet, M.

2012-02-01

322

Minor physical anomalies in schizophrenia: a meta-analysis  

PubMed Central

Numerous studies report an increased frequency of minor physical anomalies (MPAs) in schizophrenic individuals compared with controls. However, these studies vary considerably regarding the magnitude of the case-control disparity and the topographical distribution of the anomalies. A meta-analysis was carried out on the existing MPA literature in an effort to better understand the relationship between MPAs and schizophrenia. Following a literature search, 13 studies were identified that met our inclusion criteria. Mean total MPA scores were available for 11 of these studies, whereas only seven studies provided regional MPA scores. For both the total MPA and regional MPA analyses, pooled effect sizes (Hedges' g and pooled odds ratios, respectively) were calculated along with tests of heterogeneity. For the total MPA analyses, a meta-regression approach was used to explore the relationship between possible moderator variables (e.g., number of MPA scale items) and effect size heterogeneity. The magnitude of the pooled effect size for the total MPA scores was high (1.131; p < 0.001), indicating significantly more overall MPAs in schizophrenic individuals. Significant effect size heterogeneity was present (p < 0.001); however, this heterogeneity could not be explained by any of the included moderator variables. The regional MPA analysis revealed significantly increased MPAs in all six anatomical regions (p < 0.05), although the pooled odds ratios for these regions did not differ significantly from one another. These results suggest a lack of regional specificity for MPAs in schizophrenia.

Weinberg, Seth M.; Jenkins, Elizabeth A.; Marazita, Mary L.; Maher, Brion S.

2008-01-01

323

Application of higher harmonic blade feathering for helicopter vibration reduction  

NASA Technical Reports Server (NTRS)

Higher harmonic blade feathering for helicopter vibration reduction is considered. Recent wind tunnel tests confirmed the effectiveness of higher harmonic control in reducing articulated rotor vibratory hub loads. Several predictive analyses developed in support of the NASA program were shown to be capable of calculating single harmonic control inputs required to minimize a single 4P hub response. In addition, a multiple-input, multiple-output harmonic control predictive analysis was developed. All techniques developed thus far obtain a solution by extracting empirical transfer functions from sampled data. Algorithm data sampling and processing requirements are minimal to encourage adaptive control system application of such techniques in a flight environment.

Powers, R. W.

1978-01-01

324

Preliminary Rock Physics Analysis on Lodgepole Formation in Manitoba, Canada  

NASA Astrophysics Data System (ADS)

We present rock physics analysis results of Lodgepole Formation, a carbonate reservoir in Daly Field, Manitoba, Canada. We confirmed that the Lodgepole Formation can be divided into six units in the study area: Basal Limestone, Cromer Shale, Cruickshank Crinoidal, Cruickshank Shale, Daly member and Flossie Lake member from the bottom, using eight well log data and previous works. We then performed rock physics analyses on four carbonate units (Basal Limestone, Cruickshank Crinoidal, Daly and Flossie Lake), such as Vp-porosity, AI-porosity, DEM (differential effective medium) modeling, and fluid substitution analysis. In Vp-porosity domain, the top unit, Flossie Lake member has lower porosity and higher velocity, while the other units show similar porosity and velocity. We think that this results from the diagenesis of Flossie Lake member since it bounds with unconformity. However, the four units show very similar trend in Vp-porosity domain, and we can report one Vp-porosity relation for all carbonate units of the Lodgepole formation. We also found that the acoustic impedance varies more than 10% from low porosity zone (3-6%) to high porosity zone (9-12%) from AI-porosity analysis. Thus one can delineate high porosity zone from seismic impedance data. DEM modeling showed that Flossie Lake would have relatively low aspect ratio of pores than the others, which implies that the top unit has been influenced by diagenesis. To determine fluid sensitivity of carbonate units, we conducted fluid substitution on four units from 100% water to 100% oil. The top unit, Flossie Lake, showed slight increase of Vp, which seems to be density effect. The others showed small decrease of Vp, but not significant. If we observe Vp/Vs rather than Vp, the sensitivity increases. However, fluid discrimination would be difficult because of high stiffness of rock frame. In summary, three lower carbonate units of Lodgepole Formation would be prospective and high porosity zone can be delineated from seismic impedance data. However, we think that finding pay zones from seismic data would be difficult. Acknowledgement:This work was supported by the Energy Resources R&D program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No. 2009201030001A).

Kim, N.; Keehm, Y.

2012-12-01

325

Physical and Chemical Analytical Analysis: A key component of Bioforensics  

SciTech Connect

The anthrax letters event of 2001 has raised our awareness of the potential importance of non-biological measurements on samples of biological agents used in a terrorism incident. Such measurements include a variety of mass spectral, spectroscopic, and other instrumental techniques that are part of the current armamentarium of the modern materials analysis or analytical chemistry laboratory. They can provide morphological, trace element, isotopic, and other molecular ''fingerprints'' of the agent that may be key pieces of evidence, supplementing that obtained from genetic analysis or other biological properties. The generation and interpretation of such data represents a new domain of forensic science, closely aligned with other areas of ''microbial forensics''. This paper describes some major elements of the R&D agenda that will define this sub-field in the immediate future and provide the foundations for a coherent national capability. Data from chemical and physical analysis of BW materials can be useful to an investigation of a bio-terror event in two ways. First, it can be used to compare evidence samples collected at different locations where such incidents have occurred (e.g. between the powders in the New York and Washington letters in the Amerithrax investigation) or between the attack samples and those seized during the investigation of sites where it is suspected the material was manufactured (if such samples exist). Matching of sample properties can help establish the relatedness of disparate incidents, and mis-matches might exclude certain scenarios, or signify a more complex etiology of the events under investigation. Chemical and morphological analysis for sample matching has a long history in forensics, and is likely to be acceptable in principle in court, assuming that match criteria are well defined and derived from known limits of precision of the measurement techniques in question. Thus, apart from certain operational issues (such as how to prioritize such measurements in the face of limited sample availability, or how to render samples safe for handling in the analytical laboratory,) instrumental analysis of biological agents for purposes of sample matching alone is unlikely to present fundamental problems that require extensive research and development investments. The second way that the data generated by instrumental analysis can be useful to an investigation is through inferences that can be drawn regarding the processes used to grow and ''weaponize'' the agent. In contrast to the case of sample matching, there are significant R&D challenges associated with developing a robust capability that will reliably permit such inferential uses of instrumental data. Elaborating these challenges occupies the major portion of this paper.

Velsko, S P

2005-02-15

326

Harmonic Drive Adjusting Means.  

National Technical Information Service (NTIS)

An expansible, elliptical disk, in which the major axis may be minutely varied, is provided for spreading the flexible ball bearing arrangement of a conventional harmonic drive unit. The spreading of the ball bearings maintains the various parts of the un...

R. H. Lapp

1965-01-01

327

Hypercomplete circular harmonic pyramids  

Microsoft Academic Search

In this contribution we present a steerable pyramid based on a particular set of complex wavelets named circular harmonic wavelets (CHW). The proposed CHWs set constitutes a generalization of the smoothed edge wavelets introduced by Mallat, consisting of extending the local differential representation of a signal image from the first order to a generic n-th order. The key feature of

Giovanni Jacovitti; A. Manca; Alessandro Neri

1996-01-01

328

Extended range harmonic filter  

NASA Technical Reports Server (NTRS)

Two types of filters, leaky-wall and open-guide, are combined into single component. Combination gives 10 db or greater additional attenuation to fourth and higher harmonics, at expense of increasing loss of fundamental frequency by perhaps 0.05 to 0.08 db. Filter is applicable to all high power microwave transmitters, but is especially desirable for satellite transmitters.

Jankowski, H.; Geia, A. J.; Allen, C. C.

1973-01-01

329

A Harmonic Motion Experiment  

ERIC Educational Resources Information Center

We present a unit comprising theory, simulation and experiment for a body oscillating on a vertical spring, in which the simultaneous use of a force probe and an ultrasonic range finder enables one to explore quantitatively and understand many aspects of simple and damped harmonic motions. (Contains 14 figures.)

Gluck, P.; Krakower, Zeev

2010-01-01

330

Harmonically excited orbital variations  

SciTech Connect

Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs.

Morgan, T.

1985-08-06

331

Harmonic generation in clusters  

Microsoft Academic Search

A model is presented for the nonlinear response of a small cluster, with a size much smaller than the wavelength, at the third harmonic of the laser frequency. The model involves collective modes of a cold electron core confined within a positively charged ion background. The response of the electron core to the laser field is similar to that of

Mykhailo V. Fomyts’kyi; Boris N. Breizman; Alexey V. Arefiev; Charles Chiu

2004-01-01

332

Spherical harmonic molecular surfaces  

Microsoft Academic Search

Starlike surfaces can be defined in spherical coordinates by a function r(?, ?) on the unit sphere, which can be expanded in spherical harmonics to give a consequence of smooth approximations to the surface. This method has been used to approximate the solvent-accessible surface of a molecule. The coefficients in the expansion provide a small collection of numbers that characterize

Nelson L. Max; Elizabeth D. Getzoff

1988-01-01

333

Physics  

NSDL National Science Digital Library

Physics is the scientific study of the basic principles of the universe, including matter, energy, motion and force, and their interactions. Major topics include classical mechanics, thermodynamics, light and optics, electromagnetism and relativity.

K-12 Outreach,

334

Physical Disability on Children's Television Programming: A Content Analysis  

ERIC Educational Resources Information Center

Research Findings: Media representations of physical disability can influence the attitudes of child audiences. In the current study, the depiction of physical disability was analyzed in more than 400 episodes of children's television programming to better understand how media depict physical disability to children and, in turn, how exposure may…

Bond, Bradley J.

2013-01-01

335

Effect of the zero spatial harmonic in a slow electromagnetic wave on operation of relativistic backward-wave oscillators  

SciTech Connect

A linear theory of resonant backward-wave oscillators (BWOs) that takes into account the zero spatial harmonic is developed. It is shown that, depending on the phase shift, this harmonic can either increase or decrease the starting current of the device. The nonlinear theory shows the same effect of the phase shift on the maximum efficiency of the BWO. The numerical analysis of nonstationary processes has also demonstrated the effect of the phase shift on the range of beam current values in which the BWO operates in a steady-state single-frequency regime. The effect of boundary conditions at the cathode end of the slow-wave structure on the phase shift between harmonics is also analyzed. {copyright} {ital 1997 American Institute of Physics.}

Vlasov, A.N.; Nusinovich, G.S. [Institute for Plasma Research, University of Maryland, College Park, Maryland 20742-3511 (United States)] [Institute for Plasma Research, University of Maryland, College Park, Maryland 20742-3511 (United States); Levush, B. [Naval Research Laboratory, Washington, D.C. 20375-5000 (United States)] [Naval Research Laboratory, Washington, D.C. 20375-5000 (United States)

1997-05-01

336

An Analysis of Middle School Students Physical Education Physical Activity Preferences  

ERIC Educational Resources Information Center

The idea of providing student's choice over curricular offerings in physical education has gained a considerable amount of attention in recent years. The purpose of this study was to determine which physical education activities middle school students would like to have included in the yearly curriculum and if there were differences in responses…

Hill, Grant; Hannon, James C.

2008-01-01

337

Higher order harmonic detection for exploring nonlinear interactions with nanoscale resolution  

PubMed Central

Nonlinear dynamics underpin a vast array of physical phenomena ranging from interfacial motion to jamming transitions. In many cases, insight into the nonlinear behavior can be gleaned through exploration of higher order harmonics. Here, a method using band excitation scanning probe microscopy (SPM) to investigate higher order harmonics of the electromechanical response, with nanometer scale spatial resolution is presented. The technique is demonstrated by probing the first three harmonics of strain for a Pb(Zr1-xTix)O3 (PZT) ferroelectric capacitor. It is shown that the second order harmonic response is correlated with the first harmonic response, whereas the third harmonic is not. Additionally, measurements of the second harmonic reveal significant deviations from Rayleigh-type models in the form of a much more complicated field dependence than is observed in the spatially averaged data. These results illustrate the versatility of nth order harmonic SPM detection methods in exploring nonlinear phenomena in nanoscale materials.

Vasudevan, R. K.; Okatan, M. Baris; Rajapaksa, I.; Kim, Y.; Marincel, D.; Trolier-McKinstry, S.; Jesse, S.; Valanoor, N.; Kalinin, S. V.

2013-01-01

338

Evidence of high harmonics from echo-enabled harmonic generation for seeding x-ray free electron lasers.  

PubMed

Echo-enabled harmonic generation free electron lasers hold great promise for the generation of fully coherent radiation in x-ray wavelengths. Here we report the first evidence of high harmonics from the echo-enabled harmonic generation technique in the realistic scenario where the laser energy modulation is comparable to the beam slice energy spread. In this experiment, coherent radiation at the seventh harmonic of the second seed laser is generated when the energy modulation amplitude is about 2-3 times the slice energy spread. The experiment confirms the underlying physics of echo-enabled harmonic generation and may have a strong impact on emerging seeded x-ray free electron lasers that are capable of generating laserlike x rays which will advance many areas of science. PMID:22324690

Xiang, D; Colby, E; Dunning, M; Gilevich, S; Hast, C; Jobe, K; McCormick, D; Nelson, J; Raubenheimer, T O; Soong, K; Stupakov, G; Szalata, Z; Walz, D; Weathersby, S; Woodley, M

2012-01-13

339

Evidence of High Harmonics from Echo-Enabled Harmonic Generation for Seeding X-Ray Free Electron Lasers  

NASA Astrophysics Data System (ADS)

Echo-enabled harmonic generation free electron lasers hold great promise for the generation of fully coherent radiation in x-ray wavelengths. Here we report the first evidence of high harmonics from the echo-enabled harmonic generation technique in the realistic scenario where the laser energy modulation is comparable to the beam slice energy spread. In this experiment, coherent radiation at the seventh harmonic of the second seed laser is generated when the energy modulation amplitude is about 2-3 times the slice energy spread. The experiment confirms the underlying physics of echo-enabled harmonic generation and may have a strong impact on emerging seeded x-ray free electron lasers that are capable of generating laserlike x rays which will advance many areas of science.

Xiang, D.; Colby, E.; Dunning, M.; Gilevich, S.; Hast, C.; Jobe, K.; McCormick, D.; Nelson, J.; Raubenheimer, T. O.; Soong, K.; Stupakov, G.; Szalata, Z.; Walz, D.; Weathersby, S.; Woodley, M.

2012-01-01

340

Preliminary rock physics analysis on Grosmont carbonate formation, Alberta, Canada  

NASA Astrophysics Data System (ADS)

Grosmont formation in Canada is a bitumen-saturated carbonate reservoir and draw increasing attention as a possible future unconventional oil field. However, the characterization of the formation is not easy due to high geological complexity. In this paper, we report our preliminary results of rock physics modeling effort using log data from seven wells in the T85R19W4 township, Alberta, Canada. Since the acoustic and shear velocity data are not very common, we use three logging properties: gamma ray; neutron-density porosity; and resistivity. The bitumen saturation is obtained from core measurement data. From the preliminary analysis, Grosmont formation can be divided into two groups by resistivity and porosity. The lower group matches with Grosmont A and B from previous studies and upper group with Grosmont C and D. The lower group mainly consists of limestone with different clay contents. The upper group was under dolomitization and karstification during Mesozoic, and is composed of fractured dolomite and karst breccia. The two groups can be divided by 15% porosity and 100 ohm-m resistivity values. The upper group has higher porosity and higher resistivity, which indicates high bitumen saturation and better reservoir quality. In porosity-resistivity domain, some wells shows typical trend; resistivity increases as porosity decrease; however, wells from the north-eastern part does not show any consistent trends. We believe that north-eastern part of our study area has more dolomitization and karstification, thus higher heterogeneity. We report basic trends for porosity vs. resistivity using Hashin-Shtrikman bounds for upper and lower group at each well. We also plan to obtain velocity data and perform quantitative analysis on porosity-velocity relations and velocity sensitivity to bitumen saturation. Acknowledgement: This research was funded by Energy Efficiency and Resources Program of KETEP (Korea Institute of Energy Technology Evaluation and Planning), Grant No. 2008-R-ER-11-P-04-0-30-2008.

Hu, D.; Keehm, Y.

2009-12-01

341

Structural, Physical, and Compositional Analysis of Lunar Simulants and Regolith  

NASA Technical Reports Server (NTRS)

Relative to the prior manned Apollo and unmanned robotic missions, planned Lunar initiatives are comparatively complex and longer in duration. Individual crew rotations are envisioned to span several months, and various surface systems must function in the Lunar environment for periods of years. As a consequence, an increased understanding of the surface environment is required to engineer and test the associated materials, components, and systems necessary to sustain human habitation and surface operations. The effort described here concerns the analysis of existing simulant materials, with application to Lunar return samples. The interplay between these analyses fulfills the objective of ascertaining the critical properties of regolith itself, and the parallel objective of developing suitable stimulant materials for a variety of engineering applications. Presented here are measurements of the basic physical attributes, i.e. particle size distributions and general shape factors. Also discussed are structural and chemical properties, as determined through a variety of techniques, such as optical microscopy, SEM and TEM microscopy, Mossbauer Spectroscopy, X-ray diffraction, Raman microspectroscopy, inductively coupled argon plasma emission spectroscopy and energy dispersive X-ray fluorescence mapping. A comparative description of currently available stimulant materials is discussed, with implications for more detailed analyses, as well as the requirements for continued refinement of methods for simulant production.

Greenberg, Paul; Street, Kenneth W.; Gaier, James

2008-01-01

342

Adjoint Sensitivity Analysis of Orbital Mechanics: Application to Computations of Observables' Partials with Respect to Harmonics of the Planetary Gravity Fields  

NASA Technical Reports Server (NTRS)

An approach is presented to the inversion of gravity fields based on evaluation of partials of observables with respect to gravity harmonics using the solution of adjoint problem of orbital dynamics of the spacecraft. Corresponding adjoint operator is derived directly from the linear operator of the linearized forward problem of orbital dynamics. The resulting adjoint problem is similar to the forward problem and can be solved by the same methods. For given highest degree N of gravity harmonics desired, this method involves integration of N adjoint solutions as compared to integration of N2 partials of the forward solution with respect to gravity harmonics in the conventional approach. Thus, for higher resolution gravity models, this approach becomes increasingly more effective in terms of computer resources as compared to the approach based on the solution of the forward problem of orbital dynamics.

Ustinov, Eugene A.; Sunseri, Richard F.

2005-01-01

343

Double stage harmonic and interharmonic processing technique  

Microsoft Academic Search

Measurement and analysis experiences have shown great difficulties in interharmonic detection and measurement due to their small amplitudes and their consequent vulnerability from harmonics spectral leakage. A new approach that has a general validity and results fully compatible with the IEC standard is presented. This approach is based on a double stage signal processing technique; in the first stage, the

D. Gallo; R. Langella; A. Testa

2000-01-01

344

Two-dimensional echocardiography using second harmonic imaging for the diagnosis of intracardiac right-to-left shunt: a meta-analysis of prospective studies.  

PubMed

Right-to-left shunting (RLS), usually through a patent foramen ovale (PFO), has been associated with migraine, cryptogenic stroke and hypoxemia. With emerging observational studies and clinical trials on the subject of PFO, there is a need for accurate diagnosis of PFO in patients being considered for transcatheter closure. While transesophageal echo (TEE) bubble study is the current standard reference for diagnosing PFO, transthoracic echo with second harmonic imaging (TTE-HI) may be a preferable screening test for RLS due to its high accuracy and non-invasiveness. The aim of this meta-analysis was to determine the accuracy of TTE-HI compared to TEE as the reference. A systematic review of Medline, Cochrane and Embase was done for all the prospective studies assessing for intracardiac RLS using TTE-HI compared to TEE as the reference; both TTE-HI and TEE were performed with a contrast agent and a maneuver to provoke RLS in all studies. A total of 15 studies with 1995 patients fulfilled the inclusion criteria. The weighted mean sensitivity and specificity for TTE-HI were 91 and 93 % respectively. Likewise, the positive and negative likelihood ratios were 13.52 and 0.13 respectively. TTE-HI is a reliable, non-invasive test with proficient diagnostic accuracies. The high sensitivity and specificity of TTE-HI make it a useful initial screening test for RLS. If the precise anatomy is required, then TEE can be obtained before scheduling a patient for transcatheter PFO closure. PMID:24740212

Mojadidi, Mohammad Khalid; Winoker, Jared S; Roberts, Scott C; Msaouel, Pavlos; Gevorgyan, Rubine; Zolty, Ronald

2014-06-01

345

Degradation in finite-harmonic subcarrier demodulation  

NASA Technical Reports Server (NTRS)

Previous estimates on the degradations due to a subcarrier loop assume a square-wave subcarrier. This article provides a closed-form expression for the degradations due to the subcarrier loop when a finite number of harmonics are used to demodulate the subcarrier, as in the case of the buffered telemetry demodulator. We compared the degradations using a square wave and using finite harmonics in the subcarrier demodulation and found that, for a low loop signal-to-noise ratio, using finite harmonics leads to a lower degradation. The analysis is under the assumption that the phase noise in the subcarrier (SC) loop has a Tikhonov distribution. This assumption is valid for first-order loops.

Feria, Y.; Townes, S.; Pham, T.

1995-01-01

346

Women in Physics: an Analysis of the Gender Gap  

NASA Astrophysics Data System (ADS)

It is not a surprise that the number of women in physics is not impressive, and the reasons are diverse and well-known [1]. We conducted several surveys at SUNY Oswego regarding the gender gap. We examined the source of the problem and we developed possible solutions. We propose herein various strategies for short-term and long-term improvement of female representation in Physics. This insight will hopefully benefit other physics departments in which women are underrepresented. [4pt] [1] Rachel Ivie and Katie Stowe. June 2000. Women in Physics, 2000, AIP Publication Number R-430.

Ghobrial, Lillie; Evans, Michael; Maslak, Gregory; Stewart, Mark; Bontorno, Anna; Barrett, Brittany; Scott, Nicole; Ilie, Carolina

2011-03-01

347

Parallelization of the Physical-Space Statistical Analysis System (PSAS)  

NASA Technical Reports Server (NTRS)

Atmospheric data assimilation is a method of combining observations with model forecasts to produce a more accurate description of the atmosphere than the observations or forecast alone can provide. Data assimilation plays an increasingly important role in the study of climate and atmospheric chemistry. The NASA Data Assimilation Office (DAO) has developed the Goddard Earth Observing System Data Assimilation System (GEOS DAS) to create assimilated datasets. The core computational components of the GEOS DAS include the GEOS General Circulation Model (GCM) and the Physical-space Statistical Analysis System (PSAS). The need for timely validation of scientific enhancements to the data assimilation system poses computational demands that are best met by distributed parallel software. PSAS is implemented in Fortran 90 using object-based design principles. The analysis portions of the code solve two equations. The first of these is the "innovation" equation, which is solved on the unstructured observation grid using a preconditioned conjugate gradient (CG) method. The "analysis" equation is a transformation from the observation grid back to a structured grid, and is solved by a direct matrix-vector multiplication. Use of a factored-operator formulation reduces the computational complexity of both the CG solver and the matrix-vector multiplication, rendering the matrix-vector multiplications as a successive product of operators on a vector. Sparsity is introduced to these operators by partitioning the observations using an icosahedral decomposition scheme. PSAS builds a large (approx. 128MB) run-time database of parameters used in the calculation of these operators. Implementing a message passing parallel computing paradigm into an existing yet developing computational system as complex as PSAS is nontrivial. One of the technical challenges is balancing the requirements for computational reproducibility with the need for high performance. The problem of computational reproducibility is well known in the parallel computing community. It is a requirement that the parallel code perform calculations in a fashion that will yield identical results on different configurations of processing elements on the same platform. In some cases this problem can be solved by sacrificing performance. Meeting this requirement and still achieving high performance is very difficult. Topics to be discussed include: current PSAS design and parallelization strategy; reproducibility issues; load balance vs. database memory demands, possible solutions to these problems.

Larson, J. W.; Guo, J.; Lyster, P. M.

1999-01-01

348

Hypercomplete circular harmonic pyramids  

NASA Astrophysics Data System (ADS)

In this contribution we present a steerable pyramid based on a particular set of complex wavelets named circular harmonic wavelets (CHW). The proposed CHWs set constitutes a generalization of the smoothed edge wavelets introduced by Mallat, consisting of extending the local differential representation of a signal image from the first order to a generic n-th order. The key feature of the proposed representation is the use of complex operators leading to an expansion in series of polar separable complex functions, which are shown to possess the space-scale representability of the wavelets. The resulting tool is highly redundant, and for this reason is called hypercomplete circular harmonic pyramid (HCHP), but presents some interesting aspects in terms of flexibility, being suited for many image processing applications. In the present contribution the main theoretical aspects of the HCHPs are discussed along with some introductory applications.

Jacovitti, Giovanni; Manca, A.; Neri, Alessandro

1996-10-01

349

Spherical Harmonics YLM Explorer  

NSDL National Science Digital Library

This is a Java applet that creates surface plots of the spherical harmonics. The user can set the L and m indices and the resolution of the plot. There is a restriction that L must be less than or equal to 5. Results are shown as either the amplitude of the function colored by the complex phase or the real part of the function illuminated by an external light source. Plots may be rotated in three dimensions.

Kraus, Martin

2005-04-16

350

Generalized Multilevel Physical Optics (MLPO) for Comprehensive Analysis of Reflector Antennas  

Microsoft Academic Search

Recent developments of the multilevel physical optics (MLPO) algorithm aiming at the comprehensive analysis of complex reflector antenna systems are presented. The physical theory of diffraction (PTD) line integral along the rim of a reflector is combined with the physical optics (PO) surface integral within the multilevel algorithm. The multilevel scheme is also generalized to combine fields radiated by various

Christine Letrou; Amir Boag

2012-01-01

351

Effectiveness of Physical Activity Interventions for Preschoolers: A Meta-Analysis  

ERIC Educational Resources Information Center

Purpose: The purpose of the meta-analysis was to examine the effectiveness of physical activity interventions on physical activity participation among preschoolers. A secondary purpose was to investigate the influence of several possible moderator variables (e.g., intervention length, location, leadership, type) on moderate-to-vigorous physical

Gordon, Elliott S.; Tucker, Patricia; Burke, Shauna M.; Carron, Albert V.

2013-01-01

352

Comparison of the sector and usual spherical harmonic analyses of the solar magnetic field in July 2004  

NASA Astrophysics Data System (ADS)

It has been shown that sector spherical harmonic analysis, in contrast to the usual harmonic analysis, allows for an exact coordination of the solar magnetic field from the photosphere to the Earth's orbit.

Ivanov, K. G.; Kharshiladze, A. F.

2014-05-01

353

Applying Cluster Analysis to Physics Education Research Data  

ERIC Educational Resources Information Center

One major thrust of Physics Education Research (PER) is the identification of student ideas about specific physics concepts, both correct ideas and those that differ from the expert consensus. Typically the research process of eliciting the spectrum of student ideas involves the administration of specially designed questions to students. One major…

Springuel, R. Padraic

2010-01-01

354

A Meta-Analysis of College Students' Physical Activity Behaviors  

ERIC Educational Resources Information Center

The authors reviewed studies on college students' physical activity (PA) behaviors and found that previous research on this topic focused on describing college students' PA patterns and their determinants. Researchers reported that about 40% to 50% of college students are physically inactive. More important, health and PA professionals in higher…

Keating, Xiaofen Deng; Guan, Jianmin; Pinero, Jose Castro; Bridges, Dwan Marie

2005-01-01

355

Analysis of information flow security in cyber–physical systems  

Microsoft Academic Search

Information flow is a fundamental concept underlying the security of a system. Confidentiality of information in a system can be breached through unrestricted information flow. Physical components added to a cyber system considerably increase the difficulty of determining information flow and the difficulty of mitigating the corresponding confidentiality problem. Fundamentally, physical actions inherently divulge information through simple observation. This work

Ravi Akella; Han Tang; Bruce M. McMillin

2010-01-01

356

Developing Skill-Analysis Competency in Physical Education Teachers  

ERIC Educational Resources Information Center

Given the known relationship between physical inactivity and chronic disease (US Dept. of Health and Human Services [USDHHS], 2000, 2001), learning more about antecedents for physical activity engagement is an important research priority. In this vein, a number of studies have found a relationship between perceived and actual motor skill…

Lounsbery, Monica; Coker, Cheryl

2008-01-01

357

Analysis of the harmonic composition of a phase current curve for estimating the power distribution in the crucible of an electric ore smelting furnace  

NASA Astrophysics Data System (ADS)

A model is proposed for the phase of an electric ore smelting furnace with a hidden arc, and its implementation with Simulink is presented. The possibility of estimating the powers releasing in the arc and the charge from the harmonic composition of the phase current of the furnace is shown.

Rubtsov, V. P.; Elizarov, V. A.

2012-06-01

358

Numerical generation of hyperspherical harmonics for tetra-atomic systems  

NASA Astrophysics Data System (ADS)

A numerical generation method of hyperspherical harmonics for tetra-atomic systems, in terms of row-orthonormal hyperspherical coordinates-a hyper-radius and eight angles-is presented. The nine-dimensional coordinate space is split into three three-dimensional spaces, the physical rotation, kinematic rotation, and kinematic invariant spaces. The eight-angle principal-axes-of-inertia hyperspherical harmonics are expanded in Wigner rotation matrices for the physical and kinematic rotation angles. The remaining two-angle harmonics defined in kinematic invariant space are expanded in a basis of trigonometric functions, and the diagonalization of the kinetic energy operator in this basis provides highly accurate harmonics. This trigonometric basis is chosen to provide a mathematically exact and finite expansion for the harmonics. Individually, each basis function does not satisfy appropriate boundary conditions at the poles of the kinetic energy operator; however, the numerically generated linear combination of these functions which constitutes the harmonic does. The size of this basis is minimized using the symmetries of the system, in particular, internal symmetries, involving different sets of coordinates in nine-dimensional space corresponding to the same physical configuration.

Lepetit, Bruno; Wang, Desheng; Kuppermann, Aron

2006-10-01

359

DSP and GPS-based synchronized measurement system of harmonics in wide-area distribution system  

Microsoft Academic Search

With the recent progress in power electronics devices, harmonic pollution in the power system becomes a significant problem. Therefore, a great deal of attention has been paid to harmonic regulations and suppression technologies. As the utility power distribution system becomes broader and more complex, advanced harmonic measurement and analysis technologies are required. This paper presents the advanced measurement system of

Hiroyuki Ukai; Koichi Nakamura; Nobuyuki Matsui

2003-01-01

360

Improved motors for utility applications. Volume 4. Impact of harmonics. Final report  

SciTech Connect

Adjustable-speed drives in generating-station auxiliary systems cause harmonic distortion in the power supply. This detailed analysis demonstrates the heating effects of harmonics on induction motors connected to auxiliary systems. For screening purposes, the report includes a simplified analytic method for estimating harmonic effects.

Appiarius, J.C.; Houghtaling, D.W.; Lackey, D.F.; McCoy, R.M.; Miller, N.W.

1986-09-01

361

On a new harmonic selection technique for harmonic balance method  

NASA Astrophysics Data System (ADS)

This paper is intended to present a new harmonic selection technique when solving nonlinear dynamic systems with the harmonic balance method. This technique belongs to the class of method called the adaptive harmonic balance method (AHBM). The harmonic selection is based on the use of a tangent predictor and relies on a stepwise regression procedure that allows for a dynamic management of the number of selected harmonics via an addition or removal procedure. The efficiency of this method relative to the classical harmonic balance method (HBM) is then evaluated through examples; this later step will indicate that AHBM can significantly reduce the number of variables, thus leading to computational time savings without deteriorating solution quality.

Grolet, Aurélien; Thouverez, Fabrice

2012-07-01

362

Physics and Analysis at a Hadron Collider - An Introduction (1/3)  

ScienceCinema

This is the first lecture of three which together discuss the physics of hadron colliders with an emphasis on experimental techniques used for data analysis. This first lecture provides a brief introduction to hadron collider physics and collider detector experiments as well as offers some analysis guidelines. The lectures are aimed at graduate students.

None

2011-10-06

363

Cumberlandian Mollusk Conservation Program. Activity 5: Analysis of Physical Habitat.  

National Technical Information Service (NTIS)

Activity 5 of the Cumberlandian Mollusk Conservation Program (CMCP) evaluated physical conditions at 15 study reaches in the Tennessee River Valley. This was part of a multiphase project to study several environmental factors as they relate to freshwater ...

P. Ostrowski E. Speaks

1986-01-01

364

Physics Tutorials, University of Guelph  

NSDL National Science Digital Library

A series of online tutorial units with quizzes designed for students in the introductory college or university physics course. The page includes topics from math, physics, and biophysics. Remedial material includes simple math concepts. Some of these include: dimensional analysis, trigonometry, graphing on log paper, logarithms, algebra, vectors, unit conversions and significant digits. Along with these, the tutorials introduce torque and rotational motion, DC circuits, exponent growth and decay and simple harmonic motion. The author does make note that all of these tutorials are best viewed in Internet Explorer.

Teesdale, Bill

2009-03-19

365

Interruption in physical activity bout analysis: an accelerometry research issue  

PubMed Central

Background The purpose of the present investigation was to clarify the impact of the treatment of interruptions on the durations and the frequency of the physical activity (PA) bouts under free-living conditions. Methods One hundred and forty adults (50?±?7 years) wore an accelerometer (Lifecorder) for seven consecutive days under free-living conditions. According to the minutes by minutes metabolic equivalents (METs) value, the PA was divided into one of three intensity categories: light intensity PA (LPA, < 3 METs), moderate intensity PA (MPA, 3 to 6 METs), vigorous intensity PA (VPA, > 6 METs), and the sum of the MPA and VPA was defined as moderate to vigorous intensity PA (MVPA, > 3 METs). Thereafter, based on the time series data, we defined MVPA bouts as PA that was maintained at no less than 3 METs completely for 10 minutes or longer with or without allowing for a one-minute or a two-minute break (<3METs). Results The frequency and duration of the continuous MVPA bouts lasting longer than 10-min were significantly lower and shorter compared with that in the non-continuous MVPA bouts allowing a one- or two-minute interruption (4.11?±?1.65, 6.58?±?2.72 and 8.97?±?3.55 bouts/day, 71.62?±?33.66, 119.03?±?49.35 and 169.75?±?65.87 min/day, P?analysis process with regard to the accelerometer quantifying the break to reflect the real behavioral pattern and the physiological stress in such subjects remains unclear.

2014-01-01

366

Detection of weak third harmonic backscatter from nonlinear metal targets  

NASA Astrophysics Data System (ADS)

This paper will discuss how one can obtain the third-order characteristics of a metallic target even when the strength of the third-harmonic frequency component is far below that of the external noise or intentional jamming signal. The key idea lies in the fact that the digital third-order cross-trispectrum used to detect the third harmonic is primarily sensitive to the phase coherence between the transmitted fundamental and relatively weak backscattered third harmonic, rather than on the amplitude of the third harmonic. The feasibility of using digital crosstrispectral analysis to detect weak (S/N ratios of about -20 db) third harmonics will be demonstrated with the aid of simulation experiments.

Hong, J. Y.; Powers, E. J.

367

Integral function method for determination of nonlinear harmonic distortion  

NASA Astrophysics Data System (ADS)

The analysis of harmonic distortion is of prime importance for the analog and mixed integrated circuits. Recently we presented a new integral function method (IFM), based on a completely new principle, which allows the calculation of harmonic distortion using the DC output characteristic of devices or circuits. In this work we complement the integral function method to provide direct calculation of the following distortion figures: total harmonic distortion (THD), second harmonic distortion (HD2) and third harmonic distortion (HD3), voltage intercept points (VIP) and the intermodulation distortion (IMD). The comparison with the same distortion figures calculated by the Fourier coefficients (FC), by direct AC measurements and from FFT in simulators, indicates that results obtained by IFM give an excellent agreement in the full range of the analyzed active regions. The IFM combines simplicity and computer efficiency with accuracy and with the possibility to easily analyze the distortion when varying any of the circuit or device parameters.

Cerdeira, Antonio; Alemán, Miguel A.; Estrada, Magali; Flandre, Denis

2004-12-01

368

On 1-Harmonic Functions  

NASA Astrophysics Data System (ADS)

Characterizations of entire subsolutions for the 1-harmonic equation of a constant 1-tension field are given with applications in geometry via transformation group theory. In particular, we prove that every level hypersurface of such a subsolution is calibrated and hence is area-minimizing over R; and every 7-dimensional SO(2) × SO(6)-invariant absolutely area-minimizing integral current in R8 is real analytic. The assumption on the SO(2) × SO(6)-invariance cannot be removed, due to the first counter-example in R8, proved by Bombieri, De Girogi and Giusti.

Wei, Shihshu Walter

2007-12-01

369

High-order harmonic generation in laser surface ablation: current trends  

NASA Astrophysics Data System (ADS)

We review emerging concepts that have increased the efficiency of coherent XUV (extreme ultraviolet) generation through the use of laser frequency conversion in specially prepared plasmas and which have enabled high-order harmonic generation (HHG) spectroscopy to be used in spectral and structural analysis. We also present the current status of plasma HHG and examine what new trends have evolved in the field since it was reviewed last [Phys. Usp. 52 55 (2009)]. In particular, we consider new techniques for generating higher harmonics from various plasmas for the purpose of studying the physical properties of materials. It has been shown recently that HHG has application potential for many, sometimes unexpected, areas of laser radiation-matter interaction. It is argued that plasma HHG is—along with alternative coherent XUV generation—a powerful tool for a variety of spectroscopic and analytical applications.

Ganeev, R. A.

2013-08-01

370

Bi-harmonic cantilever design for improved measurement sensitivity in tapping-mode atomic force microscopy.  

PubMed

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. PMID:24784614

Loganathan, Muthukumaran; Bristow, Douglas A

2014-04-01

371

Monte Carlo harmonic-balance and drift-diffusion harmonic-balance analyses of 100-600 GHz Schottky barrier varactor frequency multipliers  

Microsoft Academic Search

To date, high frequency multipliers have been designed and analyzed using harmonic-balance codes incorporating equivalent circuit models for the diodes. These codes, however, are unable to accurately predict circuit performance at frequencies above 100 GHz and do not allow a means for studying the physics of electron transport. In order to analyze these high frequency Schottky doublers, a novel harmonic-balance

R. E. Lipsey; S. H. Jones; J. R. Jones; T. W. Crowe; L. F. Horvath; U. V. Bhapkar; R. J. Mattauch

1997-01-01

372

Cumberlandian Mollusk Conservation Program. Activity 5: analysis of physical habitat  

SciTech Connect

Activity 5 of the Cumberlandian Mollusk Conservation Program (CMCP) evaluated physical conditions at 15 study reaches in the Tennessee River Valley. This was part of a multiphase project to study several environmental factors as they relate to freshwater mussels. Areas of the Buffalo and Clinch Rivers, Copper Creek, and the Duck, Elk, Nolichucky, North Fork Holston, Paint Rock, and Powell Rivers were surveyed and measured to determine physical, hydrologic, hydraulic, substrate, and suspended sediment conditions. Data collected over a two-year period are summarized and presented in graphic and tabular form to facilitate the classification of river reaches according to habitat suitability for the endangered mussels. The effect of instream structures (low-head dams) on the nature and stability of the downstream substrates was studied. This task was conducted to determine if these dams alter the downstream physical environment to provide favorable conditions for mussel survival.

Ostrowski, P. Jr.; Speaks, E.

1986-01-01

373

[Physical activity between the ages of 55 and 75, analysis].  

PubMed

The 2008 Nutrition and Health Barometer, a national cross-sectional survey carried out by the French National Institute for Prevention and Health Education, has enabled to study the physical activity of elderly people aged 55 to 75 years. The amount of physical activity they do is not so different from that of younger adults. They have a better knowledge of the recommendations than the latter, but this does not necessarily fit their practice. This highlights the need to improve also the environment. PMID:22741323

Escalon, Hélène; Beck, François; Vuillemin, Anne

2012-01-01

374

OPTICAL FIBRES: Optical harmonic generation in hollow-core photonic-crystal fibres: analysis of optical losses and phase-matching conditions  

NASA Astrophysics Data System (ADS)

We consider hollow-core fibres with a microstructure photonic-crystal cladding, which open a unique opportunity of implementing nonlinear-optical interactions of waveguide modes with transverse sizes on the order of several microns in the gas phase. Phase-matching conditions for optical harmonic generation can be improved in higher waveguide modes of hollow-core photonic-crystal fibres by optimising parameters of the gas medium filling the fibre and characteristics of the fibre.

Naumov, A. N.; Zheltikov, Aleksei M.

2002-02-01

375

Analysis of Self-Directed Mastery Learning of Honors Physics  

ERIC Educational Resources Information Center

Self-directed learning (SDL) is an important life skill in a knowledge-based society and prepares students to persist, manage their time and resources, use logic to construct their knowledge, argue their views, and collaborate. The purpose of this study was to facilitate mastery of physics concepts through self-directedness in formative testing…

Athens, Wendy

2011-01-01

376

Physical properties analysis of nano-filled microcomposite epoxy materials  

Microsoft Academic Search

The physical properties of the insulating materials are sensitive to the constraints that they undergo. Indeed, the process of manufacturing is the first to act on these properties. Then, follow the constraints undergone by the material, which appear with the nominal conditions of use or in accelerated ones. Therefore, these properties are features of the performances of these materials. Thus,

J. Castellon; S. Agnel; A. Toureille; M. Frechette; G. Platbrood; K. C. Cole; D. Desgagnes

2007-01-01

377

Analysis of repeated measurements in physical therapy research  

Microsoft Academic Search

In this paper, I attempt to introduce physical therapists to the most common statistical tests for analysing differences between repeated measurements over time. Using the example of ‘whole-body flexibility’ recorded at six different times of day and the Statistical Package for the Social Sciences (SPSS), I discuss the advantages and disadvantages of the various approaches for analysing a simple one-factor

Greg Atkinson

2001-01-01

378

24 CFR 401.451 - PAE Physical Condition Analysis (PCA).  

Code of Federal Regulations, 2010 CFR

(1) The PAE must independently evaluate the physical condition of the project by means of a PCA. If the PAE finds any immediate threats to health and safety, the owner must complete those work items immediately, or the PAE must evaluate the project's eligibility in accordance with §...

2010-04-01

379

24 CFR 401.451 - PAE Physical Condition Analysis (PCA).  

Code of Federal Regulations, 2010 CFR

(1) The PAE must independently evaluate the physical condition of the project by means of a PCA. If the PAE finds any immediate threats to health and safety, the owner must complete those work items immediately, or the PAE must evaluate the project's eligibility in accordance with §...

2009-04-01

380

Analysis of physical and chemical parameters of bottled drinking water  

Microsoft Academic Search

Seventeen different brands of bottled drinking water, collected from different retail shops in Amritsar, were analyzed for different physical and chemical parameters to ascertain their compliability with the prescribed\\/recommended limits of the World Heath Organization (WHO) and the United States Environmental Protection Agency (USEPA). It was found that the majority of the brands tested were over-treated. Lower values of hardness,

Rakesh Kumar Mahajan; T. P. S. Walia; B. S. Lark; Sumanjit

2006-01-01

381

A Global Sensitivity Analysis Methodology for Multi-physics Applications  

Microsoft Academic Search

Experiments are conducted to draw inferences about an entire ensemble based on a selected number of observations. This applies to both physical experiments as well as computer experiments, the latter of which are performed by running the simulation models at different input configurations and analyzing the output responses. Computer experiments are instrumental in enabling model analyses such as uncertainty quantification

C H Tong; F R Graziani

2007-01-01

382

Chain models of physical behavior for engineering analysis and design  

Microsoft Academic Search

The relationship between geometry (form) and physical behavior (function) dominates many engineering activities. The lack of uniform and rigorous computational models for this relationship has resulted in a plethora of inconsistent (and thus usually incompatible) computer-aided design (CAD) tools and systems, causing unreasonable overhead in time, effort, and cost, and limiting the extent to which CAD tools are used in

Richard S. Palmer; Vadim Shapiro

1993-01-01

383

Morse Theory and Infinite Familiesof Harmonic Maps Between Spheres  

NASA Astrophysics Data System (ADS)

Existence of an infinite sequence of harmonic maps between spheres of certain dimensions was proven by Bizo? and Chmaj. This sequence shares many features of the Bartnik-McKinnon sequence of solutions to the Einstein-Yang-Mills equations as well as sequences of solutions that have arisen in other physical models. We apply Morse theoretic methods to prove existence of the harmonic map sequence and to prove certain index and convergence properties of this sequence. In addition, we generalize the result of Bizo? and Chmaj to produce infinite sequences of harmonic maps not previously known. The key features ``responsible'' for the existence and properties of the sequence are thereby seen to be the presence of a reflection (2) symmetry and the existence of a singular harmonic map of infinite index which is invariant under this symmetry.

Corlette, Kevin; Wald, Robert M.

384

HVDC-AC system interaction from AC harmonics. Volume 1. Harmonic impedance calculations. Final report  

SciTech Connect

Improved methods are needed to characterize ac system harmonic behavior for ac filter design for HVDC systems. The purpose of this General Electric Company RP1138 research is to evaluate the present filter design practice and to investigate methods for calculating system harmonic impedances. An overview of ac filter design for HVDC systems and a survey of literature related to filter design have been performed. Two methods for calculating system harmonic impedances have been investigated. In the measurement method, an instrumentation system for measuring system voltage and current has been assembled. Different schemes of using the measurements to calculate system harmonic impedances have been studied. In the analytical method, a procedure to include various operating conditions has been proposed. Computer programs for both methods have been prepared, and the results of the measurement and analytical methods analyzed. A conclusion of the project is that the measurement and analytical methods both provided reasonable results. There are correlations between the measured and analytical results for most harmonics, although there are discrepancies between the assumptions used in the two methods. A sensitivity approach has been proposed to further correlate the results. From the results of the analysis, it is recommended that both methods should be tested further. For the measurement method, more testing should be done to cover different system operating conditions. In the analytical method, more detailed models for representing system components should be studied. In addition, alternative statistical and sensitivity approaches should be attempted.

Breuer, G D; Chow, J H; Lindh, C B; Miller, N W; Numrich, F H; Price, W W; Turner, A E; Whitney, R R

1982-09-01

385

The technical analysis of the stock exchange and physics: Japanese candlesticks for solar activity  

NASA Astrophysics Data System (ADS)

In this article, we use the Japanese candlesticks, a method popular in the technical analysis of the Stock/Forex markets and apply it to a variable in physics-the solar activity. This method is invented and used exclusively for economic analysis and its application to a physical problem produced unexpected results. We found that the Japanese candlesticks are convenient tool in the analysis of the variables in the physics of the Sun. Based on our observations, we differentiated a new cycle in the solar activity.

Dineva, C.; Atanasov, V.

2013-09-01

386

Inharmonicity Analysis: A Novel Physical Method for Acoustic Screening of Dysphonia  

NASA Astrophysics Data System (ADS)

In the United States 6.8% of men, women, and children report current voice problems and approximately 29% will report some problems during their lifetime. Often this dysphonia is due to pathologies of the vocal folds. The authors (a physicist and a speech pathologist) describe an interdisciplinary approach that shows promise of detecting physiological abnormalities of the vocal folds from an analysis of the Fourier spectrum of spoken ``tokens.'' The underlying principle maintains that the normal human vocal fold is a linear oscillator that emits overtones that are very nearly precise integral values of the fundamental. Physiological problems of the vocal folds, however, introduce mechanical non-linearities that manifest themselves as frequency deviations from the ideal harmonic (that is, integral) values. The authors quantify this inharmonicity, describing and illustrating how one can obtain and analyze such data. They outline, as well, a proposed program to assess the clinical sensitivity and significance of the analysis discussed in this work.

Matteson, Sam; Lu, Fang-Ling

2008-10-01

387

A quantitative analysis of physics textbooks for scientific literacy themes  

Microsoft Academic Search

The purpose of this study was to examine the content of textbooks used in the Victorian Physics course between 1967 and 1997\\u000a for curriculum balance and emphasis on the following aspects of scientific literacy: (a) science as a body of knowledge, (b)\\u000a science as a way of investigating, (c) science as a way of thinking, and (d) the interaction between

John Wilkinson

1999-01-01

388

Harmonic Series Meets Fibonacci Sequence  

ERIC Educational Resources Information Center

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?

Chen, Hongwei; Kennedy, Chris

2012-01-01

389

Exploration method using harmonic functions  

Microsoft Academic Search

Harmonic functions provide optimal potential maps for robot navigation in a previously explored static environment. Here we investigate the performance of an algorithm for exploration based on partial updates of a harmonic potential in an occupancy grid. We consider that while the robot moves it carries along an activation window whose size is of the order of the sensor's range.

Edson Prestes e Silva Jr.; Paulo Martins Engel; Marcelo Trevisan; Marco Aurélio Pires Idiart

2002-01-01

390

Analysis of a Complex Network of Physics Concepts  

NASA Astrophysics Data System (ADS)

We construct the physics concepts network in which the physics concepts is considered as nodes. We find that this network is clearly not a random network but a scale-free network in which the distribution P(k) of the degree k follows a power law, P(k) k-? with exponent ? ? 2.41. The relevance between the physics concepts and the important concepts are studied by measuring the degree, the betweenness centrality, and the relevance strength and we find that the energy concept is most important. Also we find that the relevance strength s(k) as a function of the degree k exhibits a power-law behavior, s(k) k? with the exponent ? ? 0.15 and s(knn) as a function of the average neighbor's degree knn follows a power-law behavior, s(knn) ˜ k? nn with the exponent ? ? 0.17 for small knn. We also measured the other quantities which describe the topological properties of the network and find that it has the hierarchical property and tree-like patterns.

Kim, Hyun-Joo

2012-11-01

391

Getting to Know the Competition: A Content Analysis of Publicly and Corporate Funded Physical Activity Advertisements  

Microsoft Academic Search

The purpose of this research was to conduct a content analysis of physical activity advertisements in an effort to determine which advertisements were more likely to include features that may attract and maintain attention levels. Fifty-seven advertisements were collected from top circulation Canadian magazines. The advertisements ranged from publicly funded health promotion pieces to corporate sponsored advertisements using physical activity

Tanya R. Berry; Ron E. McCarville; Ryan E. Rhodes

2008-01-01

392

Accuracy of a hybrid Fast Physical Optics scheme for the analysis of dual reflector antennas  

Microsoft Academic Search

A novel hybrid Fast Physical Optics (FPO) algorithm for the analysis of dual reflector antennas is presented. A two-level FPO algorithm for the subreflector to main reflector propagation is proposed and combined with the multilevel FPO that is used for the main reflector to far-field computation. The accuracy of the proposed method is studied by comparison with the direct physical

Christine Letrou; Amir Boag

2006-01-01

393

A theoretical analysis of FGM thin plates based on physical neutral surface  

Microsoft Academic Search

This paper presents a theoretical analysis to the FGM (functionally graded materials) thin plates based on the physical neutral surface. Under the assumption of changeable parameters such as the Young’s modulus E and the mass density ? along the thickness of the plate, the physical neutral surface of a FGM plate is determined by the theory of thin plate when

Da-Guang Zhang; You-He Zhou

2008-01-01

394

Is Caregiving Hazardous to One's Physical Health? A Meta-Analysis  

Microsoft Academic Search

Caring for a family member with dementia is generally regarded as a chronically stressful process, with potentially negative physical health consequences. However, no quantitative analysis has been conducted on this literature. The authors combined the results of 23 studies to compare the physical health of caregivers with demographically similar noncaregivers. When examined across 11 health categories, caregivers exhibited a slightly

Peter P. Vitaliano; Jianping Zhang; James M. Scanlan

2003-01-01

395

A Multi-Dimensional Cognitive Analysis of Undergraduate Physics Students' Understanding of Heat Conduction  

ERIC Educational Resources Information Center

This study proposes a multi-dimensional approach to investigate, represent, and categorize students' in-depth understanding of complex physics concepts. Clinical interviews were conducted with 30 undergraduate physics students to probe their understanding of heat conduction. Based on the data analysis, six aspects of the participants' responses…

Chiou, Guo-Li; Anderson, O. Roger

2010-01-01

396

Harmonic oscillators and resonance series generated by a periodic unstable classical orbit  

NASA Technical Reports Server (NTRS)

The presence of an unstable periodic classical orbit allows one to introduce the decay time as a purely classical magnitude: inverse of the Lyapunov index which characterizes the orbit instability. The Uncertainty Relation gives the corresponding resonance width which is proportional to the Planck constant. The more elaborate analysis is based on the parabolic equation method where the problem is effectively reduced to the multidimensional harmonic oscillator with the time-dependent frequency. The resonances form series in the complex energy plane which is equidistant in the direction perpendicular to the real axis. The applications of the general approach to various problems in atomic physics are briefly exposed.

Kazansky, A. K.; Ostrovsky, Valentin N.

1995-01-01

397

Methods for Examining Small Literatures: Explication, Physical Analysis, and Citation Patterns.  

ERIC Educational Resources Information Center

Analyzes literature on information overload research in library studies using explication, physical analysis, and citation patterns. Makes cross-discipline comparisons with consumer science and psychology/psychiatry. Contains 93 references. (PEN)

Akin, Lynn

1998-01-01

398

The use of harmonic analysis of the strain response in Pb(Mg(1/3)Nb(2/3)) O3-based ceramics to calculate electrostrictive coefficients.  

PubMed

The electromechanical response of ceramics has long been described with Landau Devonshire phenomenology, wherein the strain response is linked to a polynomial expansion in electric field or dielectric displacement. Consequently, the electromechanical response has been modeled with a variety of basis functions. However, these models have failed to accommodate hysteresis and the harmonic response that arises with saturation phenomena. In addition, no quantitative criterion has been used to truncate the expansion. By implementing a discrete Fourier transform in conjunction with Devonshire phenomenology, these three problems can be overcome as demonstrated with a dielectrically aged, lead magnesium niobate relaxor ferroelectric well above its Tmax, i.e., operating in the electrostrictive regime. PMID:11800115

DiAntonio, C B; Williams, F A; Pilgrim, S M

2001-11-01

399

Applications of mathematical analysis of nonlinear physical systems  

SciTech Connect

This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). In this project we have sought to acquire the basic theoretical and computational capabilities needed to advance our understanding of the physical sciences. We concentrated on physical systems governed by transport equations. Transport equations were chosen because they govern many critical technologies. They govern the flow of carriers in semiconductors, the dynamics of nuclear reactors, the transport of radiation in fusion experiments, and even the probability densities of stochastic equations. Besides being important in its own right, this research serves as an important paradigm for using computers to solve other key scientific problems. Transport problems are often characterized by mean free paths that are short compared to the other critical length scales of the system. We exploit this feature to both simplify the solution of transport equations and to gain insights into the results. To explore industrial applications of the science developed in this project, a workshop was sponsored highlighting eight to ten problems from industry. Promising research avenues were uncovered that might lead to potential collaborations with industry.

Frauenfelder, H.; Hagan, P.; Sobehart, J.; Ueda, Tetsuji

1996-07-01

400

Analysis of the physical atomic forces between noble gas atoms, alkali ions and halogen ions  

NASA Technical Reports Server (NTRS)

The physical forces between atoms and molecules are important in a number of processes of practical importance, including line broadening in radiative processes, gas and crystal properties, adhesion, and thin films. The components of the physical forces between noble gas atoms, alkali ions, and halogen ions are analyzed and a data base for the dispersion forces is developed from the literature based on evaluations with the harmonic oscillator dispersion model for higher order coefficients. The Zener model of the repulsive core is used in the context of the recent asymptotic wave functions of Handler and Smith; and an effective ionization potential within the Handler and Smith wave functions is defined to analyze the two body potential data of Waldman and Gordon, the alkali-halide molecular data, and the noble gas crystal and salt crystal data. A satisfactory global fit to this molecular and crystal data is then reproduced by the model to within several percent. Surface potentials are evaluated for noble gas atoms on noble gas and salt crystal surfaces with surface tension neglected. Within this context, the noble gas surface potentials on noble gas and salt crystals are considered to be accurate to within several percent.

Wilson, J. W.; Heinbockel, J. H.; Outlaw, R. A.

1986-01-01

401

Symmetric functions and BN-invariant spherical harmonics  

Microsoft Academic Search

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

Charles F. Dunkl

2002-01-01

402

Enhancement of harmonic generation by Fresnel-lensing effects.  

PubMed

We present experimental results of enhanced second- and third-harmonic generation efficiency from Fresnel-lensing effects. We obtained enhancement by a factor of 6 in the third-harmonic yield by simply limiting the laser beam with an iris. Higher enhancement factors (up to 16) were obtained with a Fresnel zone plate. The experimental findings are in good agreement with the results of a simple theoretical analysis. PMID:16642091

Cavalieri, Stefano; Fini, Lorenzo; Sali, Emiliano; Buffa, Roberto

2006-05-01

403

SunPy: Python for Solar Physics Data Analysis  

NASA Astrophysics Data System (ADS)

In recent years, Python, a free cross platform general purpose high-level programming language, has seen widespread adoption among the scientific community resulting in the availability of wide range of software, from numerical computation and machine learning to spectral analysis and visualization. SunPy is a software suite specializing in providing the tools necessary to analyze solar and heliospheric datasets in Python. It provides a free and open-source alternative to the IDL-based SolarSoft (SSW) solar data analysis environment. We present the current capabilities of SunPy which include WCS-aware map objects that allow simple overplotting of data from multiple image FITS files; time-series objects that allow overplotting of multiple lightcurves, and integration with online services such as The Virtual Solar Observatory (VSO) and The Heliophysics Event Knowledgebase (HEK). SunPy also provides functionality that is not currently available in SSW such as advanced time series manipulation routines and support for working with solar data stored using JPEG 2000. We present examples of solar data analysis in SunPy, and show how Python-based solar data-analysis can leverage the many existing data analysis tools currently available in Python. We discuss the future goals of the project and encourage interested users to become involved in the planning and development of SunPy.

Hughitt, V. Keith; Christe, S.; Ireland, J.; Shih, A.; Mayer, F.; Earnshaw, M. D.; Young, C.; Perez-Suarez, D.; Schwartz, R.

2012-05-01

404

Quantum-Mechanics of a Spinless Particle in Combined Coulomb and Harmonic Oscillator Potentials  

Microsoft Academic Search

In this dissertation the quantum mechanics of a spinless particle in a combined Coulomb and harmonic oscillator potential is discussed. The particular potential considered is a 2:1 anisotropic harmonic oscillator combined with a concentric Coulomb potential. These two potentials are the two most studied potentials in mathematical physics. It is shown that this combined potential gives a Schrodinger equation which

Samuel Ernest Stansfield

1986-01-01

405

Physical characterization of asteroid surfaces from photometric analysis  

NASA Technical Reports Server (NTRS)

The feasibility of using photometric models like Hapke's (1981, 1984, 1986) equation for deriving physical properties of asteroids from photometric observations is discussed. Using data for Ceres and Vesta, it is shown that the incomplete phase-angle coverage limits the reliable determination of Hapke's photometric parameters from asteroid disk-integrated phase curves (the second limitation is the nonsphericity of many asteroids). However, within this limitations, certain trends among asteroids can be compared. It is shown that there is a general similarity among the Hapke's parameters other than the h parameter, which characterizes the width of the opposition surge in terms of soil structure (porosity, particle-size distribution, and the rate of compaction with depth), derived for similar objects, e.g., average C asteroids and Ceres, and average S asteroids, 1982 Apollo, and Vesta.

Helfenstein, P.; Veverka, J.

1989-01-01

406

Analysis of physical unclonable identification based on reference list decoding  

NASA Astrophysics Data System (ADS)

In this paper we advocate a new approach to item identification based on physical unclonable features. Being unique characteristics of an item, these features represent a kind of unstructured random codebook that links the identification problem to digital communications via composite hypothesis testing. Despite the obvious similarity, this problem is significantly different in that a security constraint prohibits the disclosure of the entire codebook at the identification stage. Besides this, complexity, memory storage and universality constraints should be taken into account for databases with several hundred millions entries. Therefore, we attempt to find a trade-off between performance, security, memory storage and universality constraints. A practical suboptimal method is considered based on our reference list decoding (RLD) framework. Simulation results are presented to demonstrate and support the theoretical findings.

Koval, Oleksiy; Voloshynovskiy, Sviatoslav; Beekhof, Fokko; Pun, Thierry

2008-03-01

407

An analysis of science content and representations in introductory college physics textbooks and multimodal learning resources  

NASA Astrophysics Data System (ADS)

This study features a comparative descriptive analysis of the physics content and representations surrounding the first law of thermodynamics as presented in four widely used introductory college physics textbooks representing each of four physics textbook categories (calculus-based, algebra/trigonometry-based, conceptual, and technical/applied). Introducing and employing a newly developed theoretical framework, multimodal generative learning theory (MGLT), an analysis of the multimodal characteristics of textbook and multimedia representations of physics principles was conducted. The modal affordances of textbook representations were identified, characterized, and compared across the four physics textbook categories in the context of their support of problem-solving. Keywords: college science, science textbooks, multimodal learning theory, thermodynamics, representations

Donnelly, Suzanne M.

408

Harmonic Measure of Critical Curves  

SciTech Connect

Fractal geometry of critical curves appearing in 2D critical systems is characterized by their harmonic measure. For systems described by conformal field theories with central charge c{<=}1, scaling exponents of the harmonic measure have been computed by Duplantier [Phys. Rev. Lett. 84, 1363 (2000)] by relating the problem to boundary two-dimensional gravity. We present a simple argument connecting the harmonic measure of critical curves to operators obtained by fusion of primary fields and compute characteristics of the fractal geometry by means of regular methods of conformal field theory. The method is not limited to theories with c{<=}1.

Bettelheim, E.; Rushkin, I.; Gruzberg, I.A.; Wiegmann, P. [James Frank Institute, University of Chicago, 5640 South Ellis Avenue, Chicago, Illinois 60637 (United States)

2005-10-21

409

Physical and Chemical Analytical Analysis: A key component of Bioforensics  

Microsoft Academic Search

The anthrax letters event of 2001 has raised our awareness of the potential importance of non-biological measurements on samples of biological agents used in a terrorism incident. Such measurements include a variety of mass spectral, spectroscopic, and other instrumental techniques that are part of the current armamentarium of the modern materials analysis or analytical chemistry laboratory. They can provide morphological,

S. P. Velsko

2005-01-01

410

Global and Local Sensitivity Analysis Methods for a Physical System  

ERIC Educational Resources Information Center

Sensitivity analysis is the study of how the different input variations of a mathematical model influence the variability of its output. In this paper, we review the principle of global and local sensitivity analyses of a complex black-box system. A simulated case of application is given at the end of this paper to compare both approaches.…

Morio, Jerome

2011-01-01

411

Angular behavior of synchrotron radiation harmonics  

NASA Astrophysics Data System (ADS)

The detailed analysis of angular dependence of the synchrotron radiation (SR) is presented. Angular distributions of linear and circular polarization integrated over all harmonics, well known for relativistic electron energies, are extended to include radiation from electrons that are not fully relativistic. In particular, we analyze the angular dependence of the integral SR intensity and peculiarities of the angular dependence of the first harmonics SR. Studying spectral SR intensities, we have discovered their unexpected angular behavior, completely different from that of the integral SR intensity; namely, for any given synchrotron frequency, maxima of the spectral SR intensities recede from the orbit plane with increasing particle energy. Thus, in contrast with the integral SR intensity, the spectral ones have the tendency to deconcentrate themselves on the orbit plane.

Bagrov, V. G.; Bulenok, V. G.; Gitman, D. M.; Jara, Jose Acosta; Tlyachev, V. B.; Jarovoi, A. T.

2004-04-01

412

Polarization attractors in harmonic mode-locked fiber laser.  

PubMed

We report on a polarimetry of harmonic mode-locked erbium-doped fiber laser with carbon nanotubes saturable absorber. We find new types of vector solitons with locked, switching and precessing states of polarization. The underlying physics presents interplay between birefringence of a laser cavity created by polarization controller along with light induced anisotropy caused by polarization hole burning. PMID:24977612

Habruseva, Tatiana; Mou, Chengbo; Rozhin, Alex; Sergeyev, Sergey V

2014-06-16

413

A Simple Mechanical Model for the Isotropic Harmonic Oscillator  

ERIC Educational Resources Information Center

A constrained elastic pendulum is proposed as a simple mechanical model for the isotropic harmonic oscillator. The conceptual and mathematical simplicity of this model recommends it as an effective pedagogical tool in teaching basic physics concepts at advanced high school and introductory undergraduate course levels. (Contains 2 figures.)

Nita, Gelu M.

2010-01-01

414

Simulating Harmonic Oscillator and Electrical Circuits: A Didactical Proposal  

ERIC Educational Resources Information Center

A Mathematica[TM] package is described that uses simulations and animations to illustrate key concepts in harmonic oscillation and electric circuits for students not majoring in physics or mathematics. Students are not required to know the Mathematica[TM] environment: a user-friendly interface with buttons functionalities and on-line help allows…

Albano, Giovannina; D'Apice, Ciro; Tomasiello, Stefania

2002-01-01

415

Experimental Development and Physical Analysis of Jet and Vortex Actuators  

NASA Technical Reports Server (NTRS)

The Vortex generator consists of a cavity with a lightweight actuator plate. The actuator plate acts like a piston pumping air out of the cavity on the down-stroke and sucking air into the cavity on the upstroke. The actuator is placed asymmetrically over the cavity opening, forming narrow and wide slots when viewed from the top. The actuator depending on amplitude, frequency, and slot spacing produces several flow fields (free jet, wall jet, vortex flow). Computational simulation of the actuator-generated flows have been developed and applied to several actuator flow modes. The objectives of this paper are to study the physics of the actuator-induced flow and to develop computational simulations of the actuatorgenerated flows. This work should provide an impetus for designing similar active flow control systems suitable for aircraft applications. The computational simulation uses a time-accurate full Navier-Stokes (NS) solver known as FTNS3D (a full NS version of CFL3D solver). A Multi-block moving grid has been developed and used for the computational study of the flow fields produced by the vortex generator. For three-dimensional computations, ten multi-block grids are used and for two-dimensional computations, six multiblock grids are used. The grid blocks adjacent to the actuator plate move with the plate motion, and second-order interpolation is used along the block interfaces. Periodic response of the flow has been observed to develop after three cycles of the plate sinusoidal motion.

Kandil, Osama A.; Yang, Zhi; Lachowicz, Jason T.

2000-01-01

416

Radio-physical methods of analysis for thunderstorm field perturbations  

Microsoft Academic Search

Complex field experiments have been undertaken on the basis of the observational set-up arranged in the Upper-Volga Region during the convective seasons of 2005-2010. Spectral and statistical characteristics of electric field perturbations in the vicinity of thunderstorm clouds have been investigated. Statistical analysis allowed us to relate found peculiarities with different stages of thunderstorm generator dynamics. We develop our fractal

E. A. Mareev; V. V. Klimenko; Yu. V. Shlyugaev; M. V. Shatalina; D. I. Iudin

2011-01-01

417

Integrated Analysis of Physical and Biological Pan-Arctic Change  

Microsoft Academic Search

We investigate the recent large changes that have occurred in the Arctic over the period of 1965–1995 through examination of 86 regionally-dispersed time series representing seven data types: climate indices, atmosphere, ocean, terrestrial, sea ice, fisheries, and other biological data. To our knowledge, this is the first semi-quantitative analysis of Arctic data that spans multiple disciplines and geographic regions. Although

James E. Overland; Michael C. Spillane; Nancy N. Soreide

2004-01-01

418

Spin-Weighted Cylindrical Harmonics  

Microsoft Academic Search

\\u000a As shown in Chapter 3, the spin-weighted spherical harmonics are very useful in the solution of linear nonscalar equations\\u000a and in the derivation of general expressions for the solutions of such equations. The usefulness of the spin-weighted spherical\\u000a harmonics is related to the appearance of the operators ð and \\u000a , when the equations are written in terms of spin-weighted components.

G. F. Torres Castillo

419

Echo-Enabled Harmonic Generation  

SciTech Connect

A recently proposed concept of the Echo-Enabled Harmonic Generation (EEHG) FEL uses two laser modulators in combination with two dispersion sections to generate a high-harmonic density modulation in a relativistic beam. This seeding technique holds promise of a one-stage soft x-ray FEL that radiates not only transversely but also longitudinally coherent pulses. Currently, an experimental verification of the concept is being conducted at the SLAC National Accelerator Laboratory aimed at the demonstration of the EEHG.

Stupakov, Gennady

2010-08-25

420

Analysis of broadband second harmonic generation in a trapezoidal isotropic semiconductor slab with an elliptical upper surface using total internal reflection quasi phase matching.  

NASA Astrophysics Data System (ADS)

This paper analytically describes the concept of an extremely wide broadband frequency converter with appreciable conversion efficiency in a trapezoidal isotropic semiconductor slab with an elliptical upper surface. The frequency conversion scheme corresponds to Second Harmonic Generation (SHG) using Total Internal Reflection Quasi Phase Matching (TIR-QPM). The simulation has been performed using Gallium Arsenide (GaAs) as the non-linear material, in the fundamental wavelength range of 6.8-10.8 ?m, considering ppp polarization configuration. Optimized simulation results, after considering reflection and absorption losses, show an extremely wide 3 dB bandwidth of 770 nm in a 40 mm slab with a conversion efficiency of 1.088%.

Banik, Smita; Deb, Sumita; Saha, Ardhendu

2013-01-01

421

Physical Sciences Division Interactive Plotting and Analysis Pages  

NSDL National Science Digital Library

This website provides access to atmospheric and climatological data from a variety of National Oceanic & Atmospheric Administration sources. It also contains numerous tools for retrieving and displaying the data. You can either download raw data or use the tools to construct finished data products. The user is asked to enter such information as type of analysis, time-scale, dataset, variability, and time range of data. Web pages that meet the entered criteria are then generated, and include monthly/seasonal composites, linear monthly/seasonal correlations, daily composites, United States climate division maps, time-section plots, wavelets, chi corrected heating atlas, daily data plots, and others.

422

Bayesian Logical Data Analysis for the Physical Sciences  

NASA Astrophysics Data System (ADS)

Preface; Acknowledgements; 1. Role of probability theory in science; 2. Probability theory as extended logic; 3. The how-to of Bayesian inference; 4. Assigning probabilities; 5. Frequentist statistical inference; 6. What is a statistic?; 7. Frequentist hypothesis testing; 8. Maximum entropy probabilities; 9. Bayesian inference (Gaussian errors); 10. Linear model fitting (Gaussian errors); 11. Nonlinear model fitting; 12. Markov Chain Monte Carlo; 13. Bayesian spectral analysis; 14. Bayesian inference (Poisson sampling); Appendix A. Singular value decomposition; Appendix B. Discrete Fourier transforms; Appendix C. Difference in two samples; Appendix D. Poisson ON/OFF details; Appendix E. Multivariate Gaussian from maximum entropy; References; Index.

Gregory, Phil

2010-05-01

423

Active harmonic elimination for multilevel converters  

Microsoft Academic Search

This paper presents an active harmonic elimination method to eliminate any number of specific higher order harmonics of multilevel converters with equal or unequal dc voltages. First, resultant theory is applied to transcendental equations characterizing the harmonic content to eliminate low order harmonics and to determine switching angles for the fundamental frequency switching scheme and a unipolar switching scheme. Next,

Zhong Du; L. M. Tolbert; J. N. Chiasson

2006-01-01

424

Harmonic State Space model of power electronics  

Microsoft Academic Search

This paper presents a technique for deriving the linearized Harmonic State Space model of a power electronic converter. The Harmonic State Space model, in which harmonics of state variables, inputs and outputs are posed separately in a State Space form, can be used for dynamic small signal studies, and for harmonic steady state studies. The technique can handle autonomous switches

G. N. Love; A. R. Wood

2008-01-01

425

Analysis of WiMAX Physical Layer using Spatial Diversity  

NASA Astrophysics Data System (ADS)

Broadband Wireless Access (BWA) has emerged as a promising solution for providing last mile internet access technology to provide high speed internet access to the users in the residential as well as in the small and medium sized enterprise sectors. IEEE 802.16e is one of the most promising and attractive candidate among the emerging technologies for broadband wireless access. The emergence of WiMAX protocol has attracted various interests from almost all the fields of wireless communications. MIMO systems which are created according to the IEEE 802.16-2005 standard (WiMAX) under different fading channels can be implemented to get the benefits of both the MIMO and WiMAX technologies. In this paper analysis of higher level of modulations (i.e. M-PSK and M-QAM for different values of M) with different code rates and on WiMAX-MIMO system is presented for Rayleigh channel by focusing on spatial multiplexing MIMO technique. Signal-to Noise Ratio (SNR) vs Bit Error Rate (BER) analysis has been done.

Sanghoi, Pavani; Kansal, Lavish

2012-04-01

426

Ejs Adiabatically Changing Harmonic Oscillator Model  

NSDL National Science Digital Library

The Ejs Adiabatically Changing Harmonic Oscillator model displays the frictionless dynamics of a mass on a spring where the angular frequency of the oscillator adiabatically changes with time according to: ω = ωâ + α tβ. The simulation displays the cumulative and current phase space motion as well as the area in phase space. All parameters can be changed via textboxes. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Adiabatically Changing Harmonic Oscillator model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_ehu_analytical_mechanics_adiabatic.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for Newtonian mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Aguirregabiria, Juan

2008-07-10

427

Expressing Crystallographic Textures through the Orientation Distribution Function: Conversion between Generalized Spherical Harmonic and Hyperspherical Harmonic Expansions  

NASA Astrophysics Data System (ADS)

In the analysis of crystallographic texture, the orientation distribution function (ODF) of the grains is generally expressed as a linear combination of the generalized spherical harmonics. Recently, an alternative expansion of the ODF, as a linear combination of the hyperspherical harmonics, has been proposed, with the advantage that this is a function of the angles that directly describe the axis and angle of each grain rotation, rather than of the Euler angles. This article provides the formulas required to convert between the generalized spherical harmonics and the hyperspherical harmonics, and between the coefficients appearing in their respective expansions of the ODF. A short discussion of the phase conventions surrounding these expansions is also presented.

Mason, J. K.; Schuh, C. A.

2009-11-01

428

A parametric study of harmonic rotor hub loads  

NASA Technical Reports Server (NTRS)

A parametric study of vibratory rotor hub loads in a nonrotating system is presented. The study is based on a CAMRAD/JA model constructed for the GBH (Growth Version of Blackhawk Helicopter) Mach-scaled wind tunnel rotor model with high blade twist (-16 deg). The theoretical hub load predictions are validated by correlation with available measured data. Effects of various blade aeroelastic design changes on the harmonic nonrotating frame hub loads at both low and high forward flight speeds are investigated. The study aims to illustrate some of the physical mechanisms for change in the harmonic rotor hub loads due to blade design variations.

He, Chengjian

1993-01-01

429

Multi-harmonic RF test stand for RF breakdown studies  

SciTech Connect

A multi-harmonic RF test stand is under construction at Yale Beam Physics Laboratory. It includes a frequency multiplier which can generate high power harmonics efficiently that are phase locked to the fundamental drive frequency. In a bi-modal asymmetric cavity powered by this RF source, the cavity may experience reduced exposure time to peak fields and sweeping of peak fields across their surfaces, and strong asymmetry between surfaces that may experience cathode-and anode-like fields; these phenomena are to be assessed for their influence on RF breakdown probabilities.

Jiang, Y.; Shchelkunov, S.; Yakovlev, V. P.; Solyak, N.; Kuzikov, S. V.; Hirshfield, J. L. [Beam Physics Laboratory, Yale University, New Haven, CT 06511 (United States); Omega-P, Inc., New Haven, CT 06510 (United States) and Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Omega-P, Inc., New Haven, CT 06510 (United States) and Institute of Applied Physics, Nizhny Novgorod (Russian Federation); Beam Physics Laboratory, Yale University, New Haven, CT 06511, USA and Omega-P, Inc., New Haven, CT 06510 (United States)

2012-12-21

430

Intermediate Mechanics Tutorials: Harmonic motion in two dimensions  

NSDL National Science Digital Library

This set of tutorial materials covers the topic of simple harmonic motion in two dimensions. Students examine qualitatively and quantitatively the motion of a 2D harmonic oscillator, as exemplified by a mass attached to an ideal spring. There are two interactive spreadsheets to allow students to manipulate values and graphically see the results. Students alter phase angles and material constants to develop an understanding of the physical parameters in the problem. This material also includes a pretest, example homework, and test questions. This is part of a large collection of similar tutorial materials in intermediate classical mechanics.

Wittmann, Michael C.; Ambrose, Bradley S.

2010-02-03

431

Comparison of different computed radiography systems: Physical characterization and contrast detail analysis  

Microsoft Academic Search

Purpose: In this study, five different units based on three different technologies—traditional com- puted radiography CR units with granular phosphor and single-side reading, granular phosphor and dual-side reading, and columnar phosphor and line-scanning reading—are compared in terms of physical characterization and contrast detail analysis. Methods: The physical characterization of the five systems was obtained with the standard beam condition RQA5.

Stefano Rivetti; Nico Lanconelli; Marco Bertolini; Andrea Nitrosi; Aldo Burani; Domenico Acchiappati

2010-01-01

432

PREFACE: 15th International Workshop on Advanced Computing and Analysis Techniques in Physics Research (ACAT2013)  

NASA Astrophysics Data System (ADS)

This volume of Journal of Physics: Conference Series is dedicated to scientific contributions presented at the 15th International Workshop on Advanced Computing and Analysis Techniques in Physics Research (ACAT 2013) which took place on 16–21 May 2013 at the Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China. The workshop series brings together computer science researchers and practitioners, and researchers from particle physics and related fields to explore and confront the boundaries of computing and of automatic data analysis and theoretical calculation techniques. This year's edition of the workshop brought together over 120 participants from all over the world. 18 invited speakers presented key topics on the universe in computer, Computing in Earth Sciences, multivariate data analysis, automated computation in Quantum Field Theory as well as computing and data analysis challenges in many fields. Over 70 other talks and posters presented state-of-the-art developments in the areas of the workshop's three tracks: Computing Technologies, Data Analysis Algorithms and Tools, and Computational Techniques in Theoretical Physics. The round table discussions on open-source, knowledge sharing and scientific collaboration stimulate us to think over the issue in the respective areas. ACAT 2013 was generously sponsored by the Chinese Academy of Sciences (CAS), National Natural Science Foundation of China (NFSC), Brookhaven National Laboratory in the USA (BNL), Peking University (PKU), Theoretical Physics Cernter for Science facilities of CAS (TPCSF-CAS) and Sugon. We would like to thank all the participants for their scientific contributions and for the en- thusiastic participation in all its activities of the workshop. Further information on ACAT 2013 can be found at http://acat2013.ihep.ac.cn. Professor Jianxiong Wang Institute of High Energy Physics Chinese Academy of Science Details of committees and sponsors are available in the PDF

Wang, Jianxiong

2014-06-01

433

Investigating Student Communities with Network Analysis of Interactions in a Physics Learning Center  

NASA Astrophysics Data System (ADS)

We describe our initial efforts at implementing social network analysis to visualize and quantify student interactions in Florida International University's Physics Learning Center. Developing a sense of community among students is one of the three pillars of an overall reform effort to increase participation in physics, and the sciences more broadly, at FIU. Our implementation of a research and learning community, embedded within a course reform effort, has led to increased recruitment and retention of physics majors. Finn and Rock [1997] link the academic and social integration of students to increased rates of retention. To identify these interactions, we have initiated an investigation that utilizes social network analysis to identify primary community participants. Community interactions are then characterized through the network's density and connectivity, shedding light on learning communities and participation. Preliminary results, further research questions, and future directions utilizing social network analysis are presented.

Brewe, Eric; Kramer, Laird; O'Brien, George

2009-11-01

434

The Importance of Physical Fitness versus Physical Activity for Coronary Artery Disease Risk Factors: A Cross-Sectional Analysis.  

ERIC Educational Resources Information Center

This cross-sectional study examined relationships among physical fitness, physical activity, and risk factors for coronary artery disease (CAD) in male police officers. Data from screenings and physical fitness assessments indicated physical activity must be sufficient to influence fitness before obtaining statistically significant risk-reducing…

Young, Deborah Rohm; Steinhardt, Mary A.

1993-01-01

435

The analysis of frequency-dependent characteristics for fluid detection: a physical model experiment  

NASA Astrophysics Data System (ADS)

According to the Chapman multi-scale rock physical model, the seismic response characteristics vary for different fluid-saturated reservoirs. For class I AVO reservoirs and gas-saturation, the seismic response is a high-frequency bright spot as the amplitude energy shifts. However, it is a low-frequency shadow for the Class III AVO reservoirs saturated with hydrocarbons. In this paper, we verified the high-frequency bright spot results of Chapman for the Class I AVO response using the frequency-dependent analysis of a physical model dataset. The physical model is designed as inter-bedded thin sand and shale based on real field geology parameters. We observed two datasets using fixed offset and 2D geometry with different fluidsaturated conditions. Spectral and time-frequency analyses methods are applied to the seismic datasets to describe the response characteristics for gas-, water-, and oil-saturation. The results of physical model dataset processing and analysis indicate that reflection wave tuning and fluid-related dispersion are the main seismic response characteristic mechanisms. Additionally, the gas saturation model can be distinguished from water and oil saturation for Class I AVO utilizing the frequency-dependent abnormal characteristic. The frequency-dependent characteristic analysis of the physical model dataset verified the different spectral response characteristics corresponding to the different fluid-saturated models. Therefore, by careful analysis of real field seismic data, we can obtain the abnormal spectral characteristics induced by the fluid variation and implement fluid detection using seismic data directly.

Chen, Shuang-Quan; Li, Xiang-Yang; Wang, Shang-Xu

2012-06-01

436

Electromagnetic ion beam instabilities - Growth at cyclotron harmonic wave numbers  

NASA Technical Reports Server (NTRS)

The linear theory of electromagnetic ion beam instabilities for arbitrary angles of propagation is studied, with an emphasis on the conditions necessary to generate unstable modes at low harmonics of the ion cyclotron resonance condition. The present results extend the analysis of Smith et al. (1985). That paper considered only the plasma parameters at a time during which harmonic wave modes were observed in the earth's foreshock. The parameters of that paper are used as the basis of parametric variations here to establish the range of beam properties which may give rise to observable harmonic spectra. It is shown that the growth rates of both left-hand and right-hand cyclotron harmonic instabilities are enhanced by an increase in the beam temperature anisotropy and/or the beam speed. Decreases in the beam density and/or the core-ion beta reduce the overall growth of the cyclotron harmonic instabilities but favor the growth of these modes over the growth of the nonresonant instability and thereby enhance the observability of the harmonics.

Smith, Charles W.; Gary, S. Peter

1987-01-01

437

Asymmetric Gaussian harmonic steering in second-harmonic generation  

NASA Astrophysics Data System (ADS)

Intracavity second-harmonic generation is one of the simplest of the quantum optical processes and is well within the expertise of most optical laboratories. It is well understood and characterized, both theoretically and experimentally. We show that it can be a source of continuous-variable asymmetric Gaussian harmonic steering with fields which have a coherent excitation, hence combining the important effects of harmonic entanglement and asymmetric steering in one easily controllable device, adjustable by the simple means of tuning the cavity loss rates at the fundamental and harmonic frequencies. We find that whether quantum steering is available via the standard measurements of the Einstein-Podolsky-Rosen correlations can depend on which quadrature measurements are inferred from output spectral measurements of the fundamental and the harmonic. Altering the ratios of the cavity loss rates can be used to tune the regions where symmetric steering is available, with the results becoming asymmetric over all frequencies as the cavity damping at the fundamental frequency becomes significantly greater than at the harmonic. This asymmetry and its functional dependence on frequency is a potential new tool for experimental quantum information science, with possible utility for quantum key distribution. Although we show the effect here for Gaussian measurements of the quadratures, and cannot rule out a return of the steering symmetry for some class of non-Gaussian measurements, we note here that the system obeys Gaussian statistics in the operating regime investigated and Gaussian inference is at least as accurate as any other method for calculating the necessary correlations. Perhaps most importantly, this system is simpler than any other methods we are aware of which have been used or proposed to create asymmetric steering.

Olsen, M. K.

2013-11-01

438

Multi-photon excitation fluorescence and third-harmonic generation microscopy measurements combined with confocal Raman microscopy for the analysis of layered samples of varnished oil films  

NASA Astrophysics Data System (ADS)

The non-destructive determination of layer structures in works of art remains a significant challenge. Non-linear microscopy and confocal Raman microscopy (CRM) were employed for characterisation of varnish-media layers in model samples, providing important information regarding the thickness of materials and the identification of different media in depth. Commonly found triterpenoid varnishes mastic and dammar were applied over a single layer of films of linseed oil. Non-linear microscopy of samples was carried out using a 1028-nm femtosecond laser source; both third-harmonic generation signals (THG) and three-photon fluorescence signals (3PEF) of samples were collected in an effort to measure the thickness of mono- and bi-layers; in parallel scans of larger areas were undertaken to assess heterogeneities in samples with spatial resolution of ˜2 ?m. Complementary spectroscopic information from CRM collected with both a 514.5-nm argon-ion and a 785-nm diode lasers coupled with a 100X objective and a motorised stage was carried out. Comparison of C-H stretching regions of Raman spectra allowed the differentiation between different molecular materials and the fingerprint region was employed for the depth profiling of the samples.

Nevin, A.; Comelli, D.; Osticioli, I.; Filippidis, G.; Melessanaki, K.; Valentini, G.; Cubeddu, R.; Fotakis, C.

2010-09-01

439

Analysis of carrier behavior in C60/P(VDF-TrFE) double-layer capacitor by using electric-field-induced optical second-harmonic generation measurement  

NASA Astrophysics Data System (ADS)

By using displacement current measurement (DCM) and electric-field-induced optical second-harmonic generation (EFISHG) measurement, we studied the carrier behavior in the indium-tin oxide (ITO)/Poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE))/C60/Au(or Al) capacitors. Two DCM peaks appeared asymmetrically at around -35.5 V and +30.0 V in the dark. Correspondingly, the EFISHG response from the C60 layer was observed, but the peak positions were different with respect to DCM ones. The results show that the spontaneous polarization of the ferroelectric P(VDF-TrFE) polymeric layer directly affects the electric field in the C60 layer, and thus governs the carrier motion in this layer. As a result, the C60 layer serves like an insulator in the dark, while electrons and holes are captured and released at the interface in response to the turn-over of spontaneous polarization of ferroelectric layer. On the other hand, under white light illumination, C60 layer serves like a conductor due to the increase of photogenerated mobile carriers, and these carriers dominate the carrier motions therein. Our findings here will be helpful for analyzing carrier behaviors in organic electronic devices using ferroelectric polymers.

Cui, Xiaojin; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

2013-12-01

440

Fourier Analysis of Musical Intervals  

ERIC Educational Resources Information Center

Use of a microphone attached to a computer to capture musical sounds and software to display their waveforms and harmonic spectra has become somewhat commonplace. A recent article in "The Physics Teacher" aptly demonstrated the use of MacScope in just such a manner as a way to teach Fourier analysis. A logical continuation of this project is to…

LoPresto, Michael C.

2008-01-01

441

Generation of circularly polarized high-order harmonics by two-color coplanar field mixing  

NASA Astrophysics Data System (ADS)

An efficient method is investigated for the generation of circularly polarized high-order harmonics by a bichromatic laser field whose two components with frequencies ? and 2? are circularly polarized in the same plane, but rotate in opposite directions. The generation of intense harmonics by such a driving-field configuration was already confirmed by a previous experiment. With the help of both a semiclassical three-step model as well as a saddle-point analysis, the mechanism of harmonic generation in this case is elucidated and the plateau structure of the harmonic response and their cutoffs are established. The sensitivity of the harmonic yield and the polarization of the harmonics to imperfect circular polarization of the driving fields are investigated. Optimization of both the cutoff frequency and the harmonic efficiency with respect to the intensity ratio of the two components of the driving field is discussed. The electron trajectories responsible for the emission of particular harmonics are identified. Unlike the case of a linearly polarized driving field, they have a nonzero start velocity. By comparison with the driving-field configuration where the two components rotate in the same direction, the mechanism of the intense harmonic emission is further clarified. Depending on the (unknown) saturation intensity for the bichromatic field with counter-rotating polarizations, this scheme might be of practical interest not only because of the circular polarization of the produced harmonics, but also because of their production efficiency.

Miloševi?, Dejan B.; Becker, Wilhelm; Kopold, Richard

2000-06-01

442

Standard cell electrical and physical variability analysis based on automatic physical measurement for design-for-manufacturing purposes  

NASA Astrophysics Data System (ADS)

A fully automated system for process variability analysis of high density standard cell was developed. The system consists of layout analysis with device mapping: device type, location, configuration and more. The mapping step was created by a simple DRC run-set. This database was then used as an input for choosing locations for SEM images and for specific layout parameter extraction, used by SPICE simulation. This method was used to analyze large arrays of standard cell blocks, manufactured using Tower TS013LV (Low Voltage for high-speed applications) Platforms. Variability of different physical parameters like and like Lgate, Line-width-roughness and more as well as of electrical parameters like drive current (Ion), off current (Ioff) were calculated and statistically analyzed, in order to understand the variability root cause. Comparison between transistors having the same W/L but with different layout configurations and different layout environments (around the transistor) was made in terms of performances as well as process variability. We successfully defined "robust" and "less-robust" transistors configurations, and updated guidelines for Design-for-Manufacturing (DfM).

Shauly, Eitan; Parag, Allon; Khmaisy, Hafez; Krispil, Uri; Adan, Ofer; Levi, Shimon; Latinski, Sergey; Schwarzband, Ishai; Rotstein, Israel

2011-03-01

443

Physical activity for cancer survivors: meta-analysis of randomised controlled trials  

PubMed Central

Objective To systematically evaluate the effects of physical activity in adult patients after completion of main treatment related to cancer. Design Meta-analysis of randomised controlled trials with data extraction and quality assessment performed independently by two researchers. Data sources Pubmed, CINAHL, and Google Scholar from the earliest possible year to September 2011. References from meta-analyses and reviews. Study selection Randomised controlled trials that assessed the effects of physical activity in adults who had completed their main cancer treatment, except hormonal treatment. Results There were 34 randomised controlled trials, of which 22 (65%) focused on patients with breast cancer, and 48 outcomes in our meta-analysis. Twenty two studies assessed aerobic exercise, and four also included resistance or strength training. The median duration of physical activity was 13 weeks (range 3-60 weeks). Most control groups were considered sedentary or were assigned no exercise. Based on studies on patients with breast cancer, physical activity was associated with improvements in insulin-like growth factor-I, bench press, leg press, fatigue, depression, and quality of life. When we combined studies on different types of cancer, we found significant improvements in body mass index (BMI), body weight, peak oxygen consumption, peak power output, distance walked in six minutes, right handgrip strength, and quality of life. Sources of study heterogeneity included age, study quality, study size, and type and duration of physical activity. Publication bias did not alter our conclusions. Conclusions Physical activity has positive effects on physiology, body composition, physical functions, psychological outcomes, and quality of life in patients after treatment for breast cancer. When patients with cancer other than breast cancer were also included, physical activity was associated with reduced BMI and body weight, increased peak oxygen consumption and peak power output, and improved quality of life.

2012-01-01

444

Meta-analysis of internet-delivered interventions to increase physical activity levels  

PubMed Central

Many internet-delivered physical activity behaviour change programs have been developed and evaluated. However, further evidence is required to ascertain the overall effectiveness of such interventions. The objective of the present review was to evaluate the effectiveness of internet-delivered interventions to increase physical activity, whilst also examining the effect of intervention moderators. A systematic search strategy identified relevant studies published in the English-language from Pubmed, Proquest, Scopus, PsychINFO, CINHAL, and Sport Discuss (January 1990 – June 2011). Eligible studies were required to include an internet-delivered intervention, target an adult population, measure and target physical activity as an outcome variable, and include a comparison group that did not receive internet-delivered materials. Studies were coded independently by two investigators. Overall effect sizes were combined based on the fixed effect model. Homogeneity and subsequent exploratory moderator analysis was undertaken. A total of 34 articles were identified for inclusion. The overall mean effect of internet-delivered interventions on physical activity was d?=?0.14 (p?=?0.00). Fixed-effect analysis revealed significant heterogeneity across studies (Q?=?73.75; p?=?0.00). Moderating variables such as larger sample size, screening for baseline physical activity levels and the inclusion of educational components significantly increased intervention effectiveness. Results of the meta-analysis support the delivery of internet-delivered interventions in producing positive changes in physical activity, however effect sizes were small. The ability of internet-delivered interventions to produce meaningful change in long-term physical activity remains unclear.

2012-01-01

445

Run II physics at the Fermilab Tevatron and advanced analysis methods  

SciTech Connect

The Fermilab Tevatron has the unique opportunity to explore physics at the electroweak scale with the highest ever proton-antiproton collision energy of {radical}s = 1.96 TeV and unprecedented luminosity. About 20 times more data is expected to be collected during the first phase of the collider Run II which is in its second year of data-taking. The second phase of Run II, expected to begin in 2005, will increase the integrated luminosity to about 10-15 fb{sup -1}. Discovering a low mass Higgs boson and evidence for Supersymmetry or for other new physics beyond the Standard Model are the main physics goals for Run II. It is widely recognized that the use of advanced analysis methods will be crucial to achieve these goals. I discuss the current status of Run II at the Tevatron, prospects and foreseen applications of advanced analysis methods.

Pushpalatha C Bhat

2003-06-23

446

A Practical Global Sensitivity Analysis Methodology for Multi-Physics Applications  

Microsoft Academic Search

This paper describes a global sensitivity analysis methodology for general multi-physics applications that are characterized\\u000a by strong nonlinearities and interactions in their input-output relationships, expensive simulation runs, and large number\\u000a of input parameters. We present a four-step approach consisting of (1) prescription of credible input ranges, (2) parameter\\u000a screening, (3) construction of response surfaces, and (4) quantitative sensitivity analysis on

C. Tong; F. Graziani

447

A Statistical Activity Cost Analysis of the Relationship Between Physical and Financial Aspects of Fixed Assets  

Microsoft Academic Search

In this paper, Statistical Activity Cost Analysis (SACA) is used to identify the interaction of mutually dependent physical\\u000a and financial aspects of a fixed asset-like system configuration. The novelty of the approach is, having established a rational\\u000a description of the uncertainty inherent in both domains, the analysis of their interaction. Little research to date has investigated\\u000a the duality of engineering

A. Colin; M. Falta; S. Su; L. Turner; R. Willett; R Wolff

448

A prototype imaging second harmonic interferometer  

SciTech Connect

We have built a prototype imaging second harmonic interferometer, which is intended to test critical elements of a design for a tangential array interferometer on C-Mod{sup 6}. The prototype uses a pulsed, 35 mJ, 10 Hz multimode, Nd:YAG laser, LiB{sub 3}O{sub 5} doublers, a fan beam created by a cylindrical lens, four retroreflector elements, and a CCD camera as a detector. The prototype also uses a polarization scheme in which the interference information is eventually carried by two second harmonic beams with crossed polarization. These are vector summed and differenced, and separated, by a Wollaston prism, to give two spots on the CCD. There is a pair of these spots for each retroreflector used. The phase information is directly available as the ratio of the difference to sum the intensities of the two spots. We have tested a single channel configuration of this prototype, varying the phase by changing the pressure in an air cell, and we have obtained a 5:1 light to dark ratio, and a clear sinusoidal variation of the ratio as a function of pressure change. {copyright} {ital 1997 American Institute of Physics.}

Jobes, F.C.; Bretz, N.L. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

1997-01-01

449

The Analysis of Physical Factor for X-Ray Phase Contrast Imaging  

Microsoft Academic Search

In this article, the basic principle of X-ray phase contrast imaging was firstly introduced. According to the microcosmic mechanism of interaction of the X-ray and the material, the relationship between atomic scattering factor and complex refractive index had been obtained. And then, the emphasis was given to the calculation and analysis of two important physical factors was related to the

Feng Sheng; Liu Song; Zhang Xuelong

2007-01-01

450

Data Analysis and Graphing in an Introductory Physics Laboratory: Spreadsheet versus Statistics Suite  

ERIC Educational Resources Information Center

Two methods of data analysis are compared: spreadsheet software and a statistics software suite. Their use is compared analysing data collected in three selected experiments taken from an introductory physics laboratory, which include a linear dependence, a nonlinear dependence and a histogram. The merits of each method are compared. (Contains 7…

Peterlin, Primoz

2010-01-01

451

Student Trajectories in Physics: The Need for Analysis through a Socio-Cultural Lens  

ERIC Educational Resources Information Center

An analysis of student connections through time and space relative to the core discipline of physics is attempted, as viewed through the lens of actor-network-theory, by Antonia Candela. Using lenses of cultural realities, networks, and perceived power in the discourse of one specific university in the capital city of Mexico and one undergraduate…

Zapata, Mara

2010-01-01

452

Analysis and Synthesis of Facial Image Sequences Using Physical and Anatomical Models  

Microsoft Academic Search

We present a new approach to the analysis ofdynamic facial images for the purposes of estimating and resynthesizingdynamic facial expressions. The approach exploits asophisticated generatire model of the human face originallydeveloped for realistic facial animation. The face model, whichmay be simulated and rendered at interactive rates on a graphicsworkstation, incorporates a physics-based synthetic facial tissueand a set of anatomically motivated

Demetri Terzopoulos; Keith Waters

1993-01-01

453

Analysis of the RATAN600 radiotelescope antenna with a multilevel Physical Optics algorithm  

Microsoft Academic Search

The RATAN-600 antenna is a flexible multireflector system composed of reflectors of very large dimensions. An extended system, with improved performance in the millimetric range, includes a focal receiver array. Accurate electromagnetic analysis of such a system, and simulation of three-dimensional (3D) patterns, represents a substantial computational challenge. A fast Physical Optics method based on a multilevel subdivision of the

Christine Letrou; Vladimir Khaikin; Amir Boag

454

Equivalence of physical optics and aperture field integration method in the full pattern analysis  

Microsoft Academic Search

Physical optics (PO) and the aperture field integration method (AFIM) are high frequency approximation methods which are widely used for the analysis of reflector antennas. For an offset reflector, PO predicts asymmetric far field patterns in the offset plane, while AFIM in choosing the integration plane normal to the boresight direction always predicts symmetric patterns which are generally inaccurate. AFIM,

I. Oodo; Makoto Ando

1994-01-01

455

Analysis of the low power physics test result for cycle-5 of Ulchin-2.  

National Technical Information Service (NTIS)

This report presents nuclear calculations for analysis of gamma background effect on low power physics test results for cycle-5 of Ulchin unit-2. Emphasis is put on the effect of gamma background to average boron worth and reference bank (bank D) worth me...

S. K. Zee J. H. Park B. H. Cho J. W. Song

1994-01-01

456

A Demonstration of the Analysis of Variance Using Physical Movement and Space  

ERIC Educational Resources Information Center

Classroom demonstrations help students better understand challenging concepts. This article introduces an activity that demonstrates the basic concepts involved in analysis of variance (ANOVA). Students who physically participated in the activity had a better understanding of ANOVA concepts (i.e., higher scores on an exam question answered 2…

Owen, William J.; Siakaluk, Paul D.

2011-01-01

457

Newspaper Content Analysis in Evaluation of a Community-Based Participatory Project to Increase Physical Activity  

ERIC Educational Resources Information Center

This study conducted a newspaper content analysis as part of an evaluation of a community-based participatory research project focused on increasing physical activity through policy and environmental changes, which included activities related to media advocacy and media-based community education. Daily papers (May 2003 to December 2005) from both…

Granner, Michelle L.; Sharpe, Patricia A.; Burroughs, Ericka L.; Fields, Regina; Hallenbeck, Joyce

2010-01-01

458

Postglacial evolution of Saanich Inlet, British Columbia: results of physical property and seismic reflection stratigraphic analysis  

Microsoft Academic Search

Seismic stratigraphic analysis combined with results from ODP Leg 169S deep ocean drilling within Saanich Inlet to depths greater than 100m below the seafloor provided an opportunity to study the post-glacial development of the inlet in a quantitative manner. The seismic stratigraphy of Saanich Inlet is consistent with the general stratigraphy established for southwestern British Columbia. Sediment