Search results for "Pattern Recognition"
showing 10 items of 2301 documents
Panel Discussion on Data Analysis Trends in X-Ray and γ-Ray Astronomy 30/5/84, 11°°–12°°
1985
[The text of the panel has been edited by Dr. ozel (with indispensable help from Gabi Breuer, secretary of MPIfR) from a tape recording. The words not completely understandable are noted by (?), while various inclusions for the continuity of the text are indicated by [ ]. The slides and viewgraphs presented in the panel are added as Figures and Tables.]
Dielectric versus topographic contrast in near-field microscopy
1996
Using a fully vectorial three-dimensional numerical approach (generalized field propagator, based on Green's tensor technique), we investigate the near-field images produced by subwavelength objects buried in a dielectric surface. We study the influence of the object index, size, and depth on the near field. We emphasize the similarity between the near field spawned by an object buried in the surface (dielectric contrast) and that spawned by a protrusion on the surface (topographic contrast). We show that a buried object with a negative dielectric contrast (i.e., with a smaller index than its surrounding medium) produces a near-field image that is reversed from that of an object with a posi…
Studying endocytosis in space and time by means of temporal Boolean models
2006
Endocytosis is a process by which cells carry traffic from the extracellular space into various intracellular compartments. Visualization of fluorescently tagged clathrin proteins (mediators of endocytosis) allows us to image endocytosis in real time. When imaging the plasma membrane, areas of fluorescence generated by different endocytic processes overlap spatially and temporally, forming random clumps. Here, a sequence of segmented clathrin spots is considered a realization of a non-isotropic 3D Boolean model. Estimates of the intensity, the mean perimeter and the density function of the durations of endocytic events are obtained.
Reservoir Computing with Random Skyrmion Textures
2020
The Reservoir Computing (RC) paradigm posits that sufficiently complex physical systems can be used to massively simplify pattern recognition tasks and nonlinear signal prediction. This work demonstrates how random topological magnetic textures present sufficiently complex resistance responses for the implementation of RC as applied to A/C current pulses. In doing so, we stress how the applicability of this paradigm hinges on very general dynamical properties which are satisfied by a large class of physical systems where complexity can be put to computational use. By harnessing the complex resistance response exhibited by random magnetic skyrmion textures and using it to demonstrate pattern…
Imaging of test quartz gratings with a photon scanning tunneling microscope Experiment and theory
1995
We use the differential formalism of the electromagnetic theory of gratings to interpret the images of test sinusoidal or lamellar quartz gratings obtained with a photon scanning tunneling microscope. The period of the grating is 0.5 μm, and the height of the rule is 0.2 μm. It is shown that the images depend strongly on several parameters, such as polarization or angle of incidence, with respect to the ruling direction. A systematic study of the isointensity lines above the gratings as a function of polarization is presented, and it is shown that the image contrast can be increased or decreased depending on the sample–probe distance. To model the interaction of the fiber probe with the ele…
Three-dimensional field distribution in the focal region of low-Fresnel-number axicons.
2006
Three-dimensional intensity and phase distributions generated by microaxicons are evaluated in the low-Fresnel-number regime. Apertured and nonapertured conical wavefronts may generate transverse patterns with notable deviations from the expected nondiffracting Bessel beam. First-order analytical expressions are proposed for the evaluation of the wave field produced by axicons of different Fresnel number in the focal region.
Development of the wide field imager for Athena
2015
The WFI (Wide Field Imager) instrument is planned to be one of two complementary focal plane cameras on ESA's next X-ray observatory Athena. It combines unprecedented survey power through its large field of view of 40 arcmin x 40 arcmin together with excellent count-rate capability (>= 1 Crab). The energy resolution of the silicon sensor is state-of-the-art in the energy band of interest from 0.2 keV to 15 keV, e.g. the full width at half maximum of a line at 6 keV will be <= 150 eV until the end of the nominal mission phase. This performance is accomplished by using DEPFET active pixel sensors with a pixel size of 130 μm x 130 μm well suited to the on-axis angular resolution of 5 arcsec of…
Single-output color pattern recognition using a fractional correlator
1997
A novel method for performing color image pattern recogni- tion using a fractional correlator (FC) is proposed. The input plane is illuminated with three different coherent sources of wavelengths corre- sponding to RGB (red, green, and blue) colors. The output plane pro- vides a single output peak, which is a result of an incoherent addition between the three correlations obtained per each color. By using the fractional correlator, which is a partially space variant correlator, we achieve space-variance-controlled color pattern recognition. The use of the three-color illumination can drastically increase the discrimination ability of the suggested correlator. © 1997 Society of Photo-Optical…
Rule-guided identification of cosmic-ray patterns in PLASTEX
1992
Some techniques devised in the computer science fields of pattern recognition and expert systems are being applied to the interpretation of EAS responses in the PLASTEX experiment. An attempt is made to codity in a set of rules the expertise of trained researchers who are able to recognize and classify different hit patterns even in the presence of noisy background, and in spite of imperfections in the detector response. The patterns expected to be useful include, but are not limited to, track patterns. The software described here, as a progress report, automatically finds patterns corresponding to isolated tracks, and patterns composed of tracks that connect with each other in a layer of d…
Free-space delay lines and resonances with ultraslow pulsed Bessel beams
2008
We investigate the ultraslow motion of polychromatic Bessel beams in unbounded, nondispersive media. Control over the group velocity is exercised by means of the angular dispersion of pulsed Bessel beams of invariant transverse spatial frequency, which spontaneously emerge from near-field generators. Temporal dynamics in transients and resonances over homogeneous delay lines (dielectric slabs) are also examined.