The Experts below are selected from a list of 76335 Experts worldwide ranked by ideXlab platform
Gregory A Parker - One of the best experts on this subject based on the ideXlab platform.
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state to state three atom time dependent reactive scattering in hyperspherical coordinates
Journal of Chemical Physics, 2013Co-Authors: Jeff Crawford, Gregory A ParkerAbstract:We present a time-dependent, hyperspherical wave packet method for calculating three-atom state-to-state S-matrix elements. The wave packet is propagated in time using adiabatically adjusting, principal axes hyperspherical coordinates that treat all arrangement channels equivalently, allowing the simultaneous analysis of the products in all three arrangement channels. We take advantage of the symmetry of the potential energy surface and decompose the initial wave packet into its Component irreducible Representations, propagating each Component separately. Each irreducible Representation Component of the wave packet is analyzed by projecting it onto the hyperspherical basis at a fixed, asymptotic hyperradius, and irreducible Representation dependent S-matrix elements are obtained by matching the hyperspherical projections to symmetry-adapted Jacobi coordinate boundary conditions. We obtain arrangement channel-dependent S-matrix elements as linear combinations of the irreducible Representation dependent elements. State-to-state H + H2 and F + H2 results for zero total angular momentum are presented.
Jeff Crawford - One of the best experts on this subject based on the ideXlab platform.
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state to state three atom time dependent reactive scattering in hyperspherical coordinates
Journal of Chemical Physics, 2013Co-Authors: Jeff Crawford, Gregory A ParkerAbstract:We present a time-dependent, hyperspherical wave packet method for calculating three-atom state-to-state S-matrix elements. The wave packet is propagated in time using adiabatically adjusting, principal axes hyperspherical coordinates that treat all arrangement channels equivalently, allowing the simultaneous analysis of the products in all three arrangement channels. We take advantage of the symmetry of the potential energy surface and decompose the initial wave packet into its Component irreducible Representations, propagating each Component separately. Each irreducible Representation Component of the wave packet is analyzed by projecting it onto the hyperspherical basis at a fixed, asymptotic hyperradius, and irreducible Representation dependent S-matrix elements are obtained by matching the hyperspherical projections to symmetry-adapted Jacobi coordinate boundary conditions. We obtain arrangement channel-dependent S-matrix elements as linear combinations of the irreducible Representation dependent elements. State-to-state H + H2 and F + H2 results for zero total angular momentum are presented.
Paul R Prucnal - One of the best experts on this subject based on the ideXlab platform.
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ultrafast all optical code division multiple access cdma fiber optic networks
Computer Networks and Isdn Systems, 1994Co-Authors: W C Kwong, Paul R PrucnalAbstract:Abstract With the advanced development of fiber-optics, the large bandwidth-expansion required by spread spectrum code-division multiple-access (CDMA) can now be accomodated by using a fiber-optic channel for transmission and incoherent optical signal processing for code generation and correlation. Optical synchronous CDMA (S/CDMA), a synchronous transmission format, is introduced and compared with optical (asynchronous) CDMA. Using modified prime sequence codes, S/CDMA is shown to accomodate a larger number of subscribers and more simultaneous users than CDMA. A two-user experiment demonstrating the feasibility of optical S/CDMA is performed at 10 Mbit/s (500 Mchip/s), using optical signal processing. (A chip is a bit-Representation Component; please see Section 2.) An environment in which S/CDMA would be particularly suited is also discussed. In addition, recent research shows that the feasibility of optical CDMA is also determined by the architecture of the optical encoders/decoders. The coding architecture affects, for example, the amount of power loss and length of optical delays associated with code sequence generation and correlation, which, in turn, affect the power budget, size, and cost of an optical CDMA system. Therefore, a new, modified 2 n coding architecture is proposed and compared with prime and 2 n coding architectures. Study shows that the modified 2 n architecture performs the best and is particularly suitable for ultrafast all-optical processing and waveguides implementation for the future all-optical CDMA networks. A 100 Mbit/s optical CDMA experiment in free space demonstrating the feasibility of the modified 2 n coding architecture, using a serial combination of 50/50 beam splitters and retroreflectors, at 10 Tchip/s (i.e., 100,000 chip/bit) with 100 fs laser pulses is also reported.
Mohamed Abdelmottaleb - One of the best experts on this subject based on the ideXlab platform.
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an efficient 3 d ear recognition system employing local and holistic features
IEEE Transactions on Information Forensics and Security, 2012Co-Authors: Jindan Zhou, Steven Cadavid, Mohamed AbdelmottalebAbstract:We present a complete three-dimensional (3-D) ear recognition system combining local and holistic features in a computationally efficient manner. The system is comprised of four primary Components, namely: 1) ear image segmentation; 2) local feature extraction and matching; 3) holistic feature extraction and matching; and 4) a fusion framework combining local and holistic features at the match score level. For the segmentation Component, we introduce a novel shape-based feature set, termed the Histograms of Indexed Shapes (HIS), to localize a rectangular region containing the ear. For the local feature extraction and Representation Component, we extend the HIS feature descriptor to an object-centered 3-D shape descriptor, the Surface Patch Histogram of Indexed Shapes (SPHIS), for local ear surface Representation and matching. For the holistic matching Component, we introduce a voxelization scheme for holistic ear Representation from which an efficient, voxel-wise comparison of gallery-probe model pairs can be made. The match scores obtained from both the local and holistic matching Components are fused to generate the final match scores. Experimental results conducted on the University of Notre Dame (UND) collection G dataset, containing range images of 415 subjects yielded a rank-one recognition rate of 98.3% and an equal error rate of 1.7%. These results demonstrate that the proposed approach outperforms state-of-the-art 3-D ear biometric systems. Additionally, the method is considerably more efficient compared to the state-of-the-art because it employs a sparse set of features rather than using the dense model.
A. B. Stolbov - One of the best experts on this subject based on the ideXlab platform.
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The software platform architecture for the Component-oriented development of knowledge-based systems
2018 41st International Convention on Information and Communication Technology Electronics and Microelectronics (MIPRO), 2018Co-Authors: O. A. Nikolaychuk, A. I. Pavlov, A. B. StolbovAbstract:The problem of creating a software platform for the automated iterative development of applied knowledge-based systems is considered in the article. Well-known Component-based software engineering methodology is utilized as a general approach. The proposed architecture of the software platform includes the management subsystem and a set of problem-oriented Components that, in addition to implementing the main functionality, should support the unified platform Component interface. The management sub-system provides the ability to interactively define functions of the application based on the combination of the platform Components methods via visual programming technique. The list of frequently used functions and features of knowledge-based systems and corresponding platform Components is suggested in the article. The data control Component implements methods for interacting with a data source. The next Component provides the ability to create subject domain model in the ontology form. The rule-based reasoning Component provides the ability to create a knowledge base on the top of The obtained domain ontology. The data Representation Component supplies an automatic creation of elements and forms of the user interface. As an illustrative example, the development process of the knowledge-based system for decision support in the infrastructure logistics domain is presented.