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Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
Identifying High-Dimension Subspace Subcodes Of Reed-Solomon Codes, Sarah Adams
Identifying High-Dimension Subspace Subcodes Of Reed-Solomon Codes, Sarah Adams
Sarah Spence Adams
Subspace subcodes of Reed-Solomon (SSRS) codes were introduced by Hattori, McEliece, Solomo, and Lin in the mid-1990s. These authors found a complicated dimension formula and a simple, tight lower bound on thedimension of SSRS codes over F2m. We prove a conjecture of Hattori concerning how to identify subspaces that can be used to build SSRS codes whose dimension exceeds this lower bound.
The Minimum Decoding Delay Of Maximum Rate Complex Orthogonal Space–Time Block Codes, Sarah Adams, Nathaniel Karst, Jonathan Pollack
The Minimum Decoding Delay Of Maximum Rate Complex Orthogonal Space–Time Block Codes, Sarah Adams, Nathaniel Karst, Jonathan Pollack
Sarah Spence Adams
The growing demand for efficient wireless transmissions over fading channels motivated the development ofspace-time block codes. Space-time block codes built from generalized complex orthogonal designs are particularly attractive because the orthogonality permits a simple decoupled maximum-likelihood decodingalgorithm while achieving full transmit diversity. The two main research problems for these complex orthogonalspace-time block codes (COSTBCs) have been to determine for any number of antennas the maximum rate andthe minimum decoding delay for a maximum rate code. The maximum rate for COSTBCs was determined by Liang in 2003. This paper addresses the second fundamental problem by providing a tight lower bound on …
A Parameterized Stereo Vision Core For Fpgas, Mark Chang, Stephen Longfield
A Parameterized Stereo Vision Core For Fpgas, Mark Chang, Stephen Longfield
Mark L. Chang
We present a parameterized stereo vision core suitable for a wide range of FPGA targets and stereo vision applications. By enabling easy tuning of algorithm parameters, our system allows for rapid exploration of the design space and simpler implementation of high-performance stereo vision systems. This implementation utilizes the census transform algorithm to calculate depth information from a pair of images delivered from a simulated stereo camera pair. This work advances our previous work through implementation improvements, a stereo camera pair simulation framework, and a scalable stereo vision core.
Precis: A Usercentric Word-Length Optimization Tool, Mark Chang, Scott Hauck
Precis: A Usercentric Word-Length Optimization Tool, Mark Chang, Scott Hauck
Mark L. Chang
Translating an algorithm designed for a general-purpose processor into an algorithm optimized for custom logic requires extensive knowledge of the algorithm and the target hardware. Precis lets designers analyze the precision requirements of algorithms specified in Matlab. The design time tool combines simulation, user input, and program analysis to help designers focus their manual precision optimization efforts.
Movement Detection For Power-Efficient Smartphone Wlan Localization, Mark Chang, Ilari Shafer
Movement Detection For Power-Efficient Smartphone Wlan Localization, Mark Chang, Ilari Shafer
Mark L. Chang
Mobile phone services based on the location of a user have increased in popularity and importance, particularly with the proliferation of feature-rich smartphones. One major obstacle to the widespread use of location-based services is the limited battery life of these mobile devices and the high power costs of many existing approaches. We demonstrate the effectiveness of a localization strategy that performs full localization only when it detects a user has finished moving. We characterize the power use of a smartphone, then verify our strategy using models of long-term walk behavior, recorded data, and device implementation. For the same sample period, …
Dynamic Monopolies And Feedback Vertex Sets In Hexagonal Grids, Sarah Spence Adams, Denise Troxell, S. Luke Zinnen
Dynamic Monopolies And Feedback Vertex Sets In Hexagonal Grids, Sarah Spence Adams, Denise Troxell, S. Luke Zinnen
Sarah Spence Adams
In a majority conversion process, the vertices of a graph can be in one of the two states, colored or uncolored, and these states are dynamically updated so that a vertex becomes colored at a certain time period if at least half of its neighbors were in the colored state in the previous time period. A dynamic monopoly is a set of vertices in a graph that when initially colored will eventually cause all vertices in the graph to become colored. This paper establishes a connection between dynamic monopolies and the well-known feedback vertex sets which are sets of vertices …
Noise-Induced Oscillations In An Actively Mode-Locked Laser, Kelly Black, John Geddes
Noise-Induced Oscillations In An Actively Mode-Locked Laser, Kelly Black, John Geddes
John B. Geddes
Oscillations induced by noise are examined for an actively mode-locked laser. Additive noise, proportional noise, and combined noise are considered. Spatial noise is approximated by Hermite expansions and temporal noise is approximated via an approximation of the variance of the random variable using a fourth-order Adams–Bashforth scheme. The approach is verified on a sample problem and used to explore the governing equations for a mode-locked laser. The inclusion of multiplicative noise leads to much wider pulses and much longer intervals between pulses.