Search results for "harmonic"
showing 10 items of 984 documents
NEAR INFRARED PICOSECOND PULSED BACKWARD SECOND-HARMONIC-GENERATION IN PERIODICALLY-POLED LITHIUM NIOBATE
2011
We report on backward second-harmonic-generation in bulk periodically-poled congruent lithium niobate with a 3.2μm period. A picosecond pulsed laser allowed us exciting a resonance at 1722nm. The resonances were also resolved by temperature tuning.
Photoionization of adsorbates on sites with non-axial local symmetry. An example of the symmetry group
1996
We present an analysis of the influence of the local adsorption site symmetry on the angular distribution of photoelectrons ejected from adsorbed atoms or molecules. This analysis applies to photoelectron spectra obtained with photons of any energy in the VUV (photoelectron spectroscopy) or x-ray (XPS) regions, provided that the associated wave of the electron `sees' the neighbouring surface atoms. The adsorbate - substrate system is modelled by a cluster of symmetry group consisting of an adsorbate and several atoms of the substrate. The analysis applies also to clean surfaces of symmetry and to molecules of the symmetry group fixed in space. This local symmetry analysis is an alternative …
On continua comparable with all continua
1999
Abstract A collection of continua is described such that each continuum either is incomparable with some element of the collection, or it is a continuous image of the harmonic fan. As a consequence, a characterization of continua comparable with all continua is obtained.
Fractional-order nonlinear hereditariness of tendons and ligaments of the human knee
2020
In this paper the authors introduce a nonlinear model of fractional-order hereditariness used to capture experimental data obtained on human tendons of the knee. Creep and relaxation data on fibrous tissues have been obtained and fitted with logarithmic relations that correspond to power-laws with nonlinear dependence of the coefficients. The use of a proper nonlinear transform allows one to use Boltzmann superposition in the transformed variables yielding a fractional-order model for the nonlinear material hereditariness. The fundamental relations among the nonlinear creep and relaxation functions have been established, and the results from the equivalence relations have been contrasted wi…
Shift- and scale-invariant recognition of contour objects with logarithmic radial harmonic filters.
2008
The phase-only logarithmic radial harmonic (LRH) filter has been shown to be suitable for scale-invariant block object recognition. However, an important set of objects is the collection of contour functions that results from a digital edge extraction of the original block objects. These contour functions have a constant width that is independent of the scale of the original object. Therefore, since the energy of the contour objects decreases more slowly with the scale factor than does the energy of the block objects, the phase-only LRH filter has difficulties in the recognition tasks when these contour objects are used. We propose a modified LRH filter that permits the realization of a shi…
Ferrocene-quinoxaline Y-shaped chromophores as fascinating second-order NLO building blocks for long lasting highly active SHG polymeric films
2016
The first example of a Y-shaped ferrocene quinoxaline derivative with a surprisingly high and stable second harmonic generation (SHG) response in composite polymeric films is reported. The interesting quadratic hyperpolarizability values of different substituted Y-shaped chromophores are also investigated in solution by the EFISH technique.
Dynamic Fast Imaging Employing Steady State Acquisition Magnetic Resonance Imaging of the Vocal Tract in One Overtone Male Singer: Our Preliminary Ex…
2022
Summary Aims To demonstrate physiological changing of vocal tract's structures during overtone singing with commercial magnetic resonance imaging (MRI) Fast Imaging Employing Steady State Acquisition (FIESTA) dynamic sequence. Methods and Materials A 1.5 T MRI with a 16 channel head-and-neck coil and a FIESTA sequence were used. A temporal resolution of 0.155 sec (7 image/s). A single professional singer was studied. The MR acquisition is made while the singer performed a predetermined singing sequence. Three different overtone singing techniques were examined (L-technique, J-technique, and NG technique) and one effect (Ezengileer) applied to L-technique. For each overtone technique we eval…
Assessment of systolic left ventricular function: a multi-centre comparison of cineventriculography, cardiac magnetic resonance imaging, unenhanced a…
2005
Aims To assess the agreement of left ventricular ejection fraction (LVEF) determinations from unenhanced echocardiography, contrast-enhanced echocardiography, magnetic resonance imaging (MRI), and cineventriculography as well as the inter-observer agreement for each method. Methods and results In 120 patients, with evenly distributed EF-groups (G 55, 35-55, L 35%), cineventriculography, unenhanced echocardiography with second harmonic imaging, and contrast echocardiography at tow mechanical index with iv administration of SonoVueR were performed. In addition, cardiac MRI at 1.5T using a steady-state free precession sequence was performed in a subset of 55 patients. On-site, and two blinded …
Perception of musical tension in short chord sequences: The influence of harmonic function, sensory dissonance, horizontal motion, and musical traini…
1996
This study investigates the effect of four variables (tonal hierarchies, sensory chordal consonance, horizontal motion, and musical training) on perceived musical tension. Participants were asked to evaluate the tension created by a chord X in sequences of three chords {C major → X → C major} in a C major context key. The X chords could be major or minor triads major-minor seventh, or minor seventh chords built on the 12 notes of the chromatic scale. The data were compared with Krumhansl’s (1990) harmonic hierarchy and with predictions of Lerdahl’s (1988) cognitive theory, Hutchinson and Knopoff’s (1978) and Parncutt’s (1989) sensory-psychoacoustical theories, and the model of horizontal mo…
Reexamining Different Factors of the Resonance-Enhanced High-Order Harmonic Generation in Atomic and Nanoparticle Laser-Induced Tin Plasmas
2021
We reexamine the resonance enhancement of a single harmonic emission during the propagation of ultrafast pulses through atomic and nanoparticle tin-containing laser-induced plasma (LIP). We compare the single atomic Sn and Sn nanoparticle plasmas to demonstrate a distinction in the enhancement factor of the single harmonic in the case of fixed and tunable near-infrared pulses. The analysis of the dynamics of Sn LIP shows the range of optimal delays between heating and driving pulses (130–180 ns), at which the maximal harmonic yield can be achieved. The enhancements of the 17th and 18th harmonics of 806 nm pulses were analyzed in the case of single-color and two-color pumps of LIP, showing u…