442,567 research outputs found
Test of mode-division multiplexing and demultiplexing in free-space with diffractive transformation optics
open5openGIANLUCA RUFFATO, 1; FILIPPO ROMANATO, ; 1Department of Physics and Astronomy ‘G. Galilei’, University of Padova; 2Laboratory for Nanofabrication of Nanodevices, c.so Stati Uniti 4GIANLUCA RUFFATO, 1; Romanato, Filippo; Ruffato, Gianluca; Astronomy ‘. G. Galilei’, University of Padova; 2Laboratory for Nanofabrication of Nanodevices, c. so Stati Uniti
A Pattern Based Approach for Re-engineering Non-Ontological Resources into Ontologies
With the goal of speeding up the ontology development process, ontology engineers are starting to reuse as much as possible available ontologies and non-ontological resources such as classification schemes, thesauri, lexicons and folksonomies, that already have some degree of consensus. The reuse of such non-ontological resources necessarily involves their re-engineering into ontologies. Non-ontological resources are highly heterogeneous in their data model and contents: they encode different types of knowledge, and they can be modeled and implemented in different ways. In this paper we present (1) a typology for non-ontological resources, (2) a pattern based approach for re-engineering non-ontological resources into ontologies, and (3) a use case of the proposed approach
Non-paraxial design and fabrication of a compact OAM sorter in the telecom infrared
A novel optical device is designed and fabricated in order to overcome the
limits of the traditional sorter based on log-pol optical transformation for
the demultiplexing of optical beams carrying orbital angular momentum (OAM).
The proposed configuration simplifies the alignment procedure and significantly
improves the compactness and miniaturization level of the optical architecture.
Since the device requires to operate beyond the paraxial approximation, a
rigorous formulation of transformation optics in the non-paraxial regime has
been developed and applied. The sample has been fabricated as 256-level
phase-only diffractive optics with high-resolution electron-beam lithography,
and tested for the demultiplexing of OAM beams at the telecom wavelength of
1310 nm. The designed sorter can find promising applications in next-generation
optical platforms for mode-division multiplexing based on OAM modes both for
free-space and multi-mode fiber transmission.Comment: 12 pages, 8 figure
Supersymmetric mode converters
Originally developed in the context of quantum field theory, the concept of
supersymmetry (SUSY) can be used to systematically design a new class of
optical structures. In this work, we demonstrate how key features arising from
optical supersymmetry can be exploited to control the flow of light for mode
division multiplexing applications. Superpartner configurations are
experimentally realized in coupled optical networks, and the corresponding
light dynamics in such systems are directly observed. We show that SUSY can be
judiciously utilized to remove the fundamental mode of a multimode optical
structure, while establishing global phase matching conditions for the
remaining set of modes. Along these lines, supersymmetry may serve as a
promising platform for a new generation of versatile optical components with
novel properties and functionalities.Comment: 14 pages, 4 figure
Investigations of vegetation and soils information contained in LANDSAT Thematic Mapper and Multispectral Scanner data
An extension of the TM tasseled cap transformation to reflectance factor data is presented, and the basic concepts underlying the tasseled cap transformations are described. The ratio of TM bands 5 and 7, and TM tasseled cap wetness, are both shown to offer promise of direct detection of available soil moisture. Some effects of organic matter and other soil characteristics or constituents on TM tasseled cap spectral response are also considered
Development, implementation and evaluation of satellite-aided agricultural monitoring systems
Research supporting the use of remote sensing for inventory and assessment of agricultural commodities is summarized. Three task areas are described: (1) corn and soybean crop spectral/temporal signature characterization; (2) efficient area estimation technology development; and (3) advanced satellite and sensor system definition. Studies include an assessment of alternative green measures from MSS variables; the evaluation of alternative methods for identifying, labeling or classification targets in an automobile procedural context; a comparison of MSS, the advanced very high resolution radiometer and the coastal zone color scanner, as well as a critical assessment of thematic mapper dimensionally and spectral structure
Design principles of hardware-based phong shading and bump-mapping
The VISA+ hardware architecture is the first of a new generation of graphics accelerators designed primarily to render bump-, texture-, environment- and environment-bump-mapped polygons. This paper presents examples of the main graphical capabilities and discusses methods and simplifications used to create high quality images. One of the key concepts in the VISA+ design, the use of reflectance cubes, is predestined for environment mapping. In combination with bump- and texture-mapping it shows the strength of our new architecture. Furthermore it justifies some of the decisions made during simulation and development of the complex VISA+ architecture
Understanding and utilization of Thematic Mapper and other remotely sensed data for vegetation monitoring
The TM Tasseled Cap transformation, which provides both a 50% reduction in data volume with little or no loss of important information and spectral features with direct physical association, is presented and discussed. Using both simulated and actual TM data, some important characteristics of vegetation and soils in this feature space are described, as are the effects of solar elevation angle and atmospheric haze. A preliminary spectral haze diagnostic feature, based on only simulated data, is also examined. The characteristics of the TM thermal band are discussed, as is a demonstration of the use of TM data in energy balance studies. Some characteristics of AVHRR data are described, as are the sensitivities to scene content of several LANDSAT-MSS preprocessing techniques
- …