427 research outputs found
Finding of the optimal parameters of animated and stereographic rainbow diffractive images
We have considered the basic aspects of the technology of animated and
stereographic rainbow images. These images can be included in Optical Security Devices
(OSDs) in order to increase their structure complexity and to improve their protective
properties. The cited technology provides, on the one hand, a simple identification on the
visual level of verification and, on the other hand, the sufficient reliability against
counterfeits. The last property is achieved at first by the division of the elemental unit on
elemental regions of any adjusted shape with outline of the precision that is inaccessible
for the recreation without Electron Beam Lithography Equipment (EBLE) which is used
for the recording of OSDs. Second, the used encoding methods also assure the certain
reliability.
In the context of the paper, the theoretical discussion based a quantitative formulation of
the Huygens--Fresnel law of the diffraction on an elemental diffractive grating is carried
out. For other definite Conditions of Lighting and Observation of Diffracting Light
(CLODL), the correlation between the slope angle of diffraction grating strokes and the
corresponding horizontal parallax angle is got; and the parameter which defines the
channel selection (the quality of splitting into separate channels) is introduced. The rule
for the definition of the wavelength and the intensity of light that diffracts on a given
grating under certain CLODL is derived as well. This fact allows one to create the
software utility that models the behavior of anigrams or stereograms.
An algorithm of the synthesis of anigrams and stereograms as parts of OSDs using the
technology of a composite “figure” elemental unit (that is composed from parts of any
shape) and applying the halftone encoding by the period, filling, and achromaticity or all
these parameters at once is elaborated, and its software implementation is constructed.
The criteria for the choice of such anigram’s parameters as the resolution, number of
channels, and angle distances between them are elaborated. In order to check them, the
results of tests are summarized. The investigation of the optimal parameters of halftone
images’ encoding finding is implemented, and the results obtained for the tough and
flexible linkings of a channel to the subregion of an elemental unit for hatching images
are compared
The Dynamics of a Rigid Body in Potential Flow with Circulation
We consider the motion of a two-dimensional body of arbitrary shape in a
planar irrotational, incompressible fluid with a given amount of circulation
around the body. We derive the equations of motion for this system by
performing symplectic reduction with respect to the group of volume-preserving
diffeomorphisms and obtain the relevant Poisson structures after a further
Poisson reduction with respect to the group of translations and rotations. In
this way, we recover the equations of motion given for this system by Chaplygin
and Lamb, and we give a geometric interpretation for the Kutta-Zhukowski force
as a curvature-related effect. In addition, we show that the motion of a rigid
body with circulation can be understood as a geodesic flow on a central
extension of the special Euclidian group SE(2), and we relate the cocycle in
the description of this central extension to a certain curvature tensor.Comment: 28 pages, 2 figures; v2: typos correcte
The restricted two-body problem in constant curvature spaces
We perform the bifurcation analysis of the Kepler problem on and .
An analogue of the Delaunay variables is introduced. We investigate the motion
of a point mass in the field of the Newtonian center moving along a geodesic on
and (the restricted two-body problem). When the curvature is small,
the pericenter shift is computed using the perturbation theory. We also present
the results of the numerical analysis based on the analogy with the motion of
rigid body.Comment: 29 pages, 7 figure
Multilevel computer-generated holograms for reconstructing 3-D images in combined optical-digital security devices
Computer-generated holograms (CGHs) integrated within combined optical-digital security devices (CO/DSDs) are described in this work. They can restore the monochrome and color 3D images in white light. To record them, the Electron Beam Lithography (EBL) is used. Our investigations on optimization of synthesis and recording the CO/DSDs with the integrated in it multilevel CGHs of 3D images possessed horizontal parallax only (HPO) are presented here. The CGH fabrication process is mainly composed of two parts: calculation of the interferogram data (ID) and their recording. Calculation of the ID is done as follows: firstly, the geometrical and optical constants of recording scheme and the object surface represented by the elemental self-radiating areas, are determined, secondly, the basic parameters accounting for discretization of ID in hologram plane is defined. The ID values can be derived by calculation of the necessary elemental object areas bipolar intensities sum. Next, over suitable quantization of ID, recording the rectangle data appropriate for EBL onto glass coated with non-organic photoresist based on As₄₀S₄₀Se₂₀ is performed. We have also investigated reciprocal influence of an optical part of the CO/DSD and a digital one
The Spinning Particles as a Nonlinear Realizations of the Superworldline Reparametrization Invariance
The superdiffeomorphisms invariant description of - extended spinning
particle is constructed in the framework of nonlinear realizations approach.
The action is universal for all values of and describes the time evolution
of different group elements of the superdiffeomorphisms group of the
superspace. The form of this action coincides with the one-dimensional
version of the gravity action, analogous to Trautman's one.Comment: 4 pages, RevTe
The last integrable case of kozlov-Treshchev Birkhoff integrable potentials
We establish the integrability of the last open case in the Kozlov-Treshchev
classification of Birkhoff integrable Hamiltonian systems. The technique used
is a modification of the so called quadratic Lax pair for Toda lattice
combined with a method used by M. Ranada in proving the integrability of the
Sklyanin case.Comment: 13 page
Measurement of and Structure Functions in Low Region with the IHEP-JINR Neutrino Detector
The isoscalar structure functions and are measured as functions
of averaged over all permissible for the range of 6 to 28 GeV of
incident neutrino (anti-neutrino) energy at the IHEP-JINR Neutrino Detector.
The QCD analysis of structure function provides
MeV under the assumption of QCD
validity in the region of low . The corresponding value of the strong
interaction constant agrees with the
recent result of the CCFR collaboration and with the combined LEP/SLC result.Comment: 11 pages, 1 Postscript figure, LaTeX. Talk given at the 7th
International Workshop on Deep Inelastic Scattering and QCD (DIS 99),
Zeuthen, Germany, 19-23 Apr 199
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