On q-ary codes correcting all unidirectional errors of a limited magnitude

We consider codes over the alphabet Q={0,1,..,q-1}intended for the control of unidirectional errors of level l. That is, the transmission channel is such that the received word cannot contain both a component larger than the transmitted one and a component smaller than the transmitted one. Moreover, the absolute value of the difference between a transmitted component and its received version is at most l. We introduce and study q-ary codes capable of correcting all unidirectional errors of level l. Lower and upper bounds for the maximal size of those codes are presented. We also study codes for this aim that are defined by a single equation on the codeword coordinates(similar to the Varshamov-Tenengolts codes for correcting binary asymmetric errors). We finally consider the problem of detecting all unidirectional errors of level l.Comment: 22 pages,no figures. Accepted for publication of Journal of Armenian Academy of Sciences, special issue dedicated to Rom Varshamo

Diversity combining ARQ over the m(> 2)-ary unidirectional channel

In diversity combining automatic repeat request (ARQ), erroneous packets are combined together forming a single, more reliable, packet. In this thesis, we give a diversity combining scheme for the m-ary unidirectional channel. A system using the given scheme with a t-unidirectional error detecting code is able to correct up to Emax = floor(t/2) unidirectional errors. To use the given scheme, the decoder should be able to decide the error type (increasing or decreasing). Hence, we give simple techniques to make this decision for various unidirectional error detecting codes

Limited magnitude error control codes

A relatively new model of error control is the limited magnitude error over high radix channels. In this error model, the error magnitude does not exceed a certain limit known beforehand. In this dissertation, we study systematic error control codes for common channels under the assumption that the maximum error magnitude is known a priori. Optimal codes correcting all asymmetric and symmetric errors are given. Further, as it is often the case that we only need to correct a small number of errors, codes that can correct a single error over asymmetric and symmetric channels are also proposed. The designed codes achieve higher code rates than single error correcting codes previously given in the literature. From the error detection point of view, we study both all and t error detecting codes for asymmetric/unidirectional channels and design close-to-optimal codes. Finally, we show how the all asymmetric error correcting codes proposed in this dissertation can be used to detect all symmetric errors

Quantitative Assessment of Tropical Cylcone Simulation Sensitivity in the Community Atmosphere Model.

This work conducted nearly two thousand idealized AGCM simulations to systematically assess the sensitivities of simulated Tropical cyclone (TC) characteristics to changes in model input and evaluate the performance of three surrogate models for approximating the behavior of numerical models. The TC characteristics are intensity, precipitation rate, longwave cloud radiative forcing (LWCF), shortwave cloud radiative forcing (SWCF), cloud liquid water path (LWP) and ice water path (IWP). The National Center for Atmospheric Research (NCAR)/Department of Energy (DOE) Community Atmosphere Model (CAM) version 5.1.1 is adopted. First, the Reed-Jablonowski TC test case was upgraded to a version with background vertical wind shear, in which the well-known shear-induced intensity change and structural asymmetry in tropical cyclones are well captured. Then, a statistical framework, consisting of a combination of Latin Hypercube Sampling (LHS) and surrogate models, is used to investigate the sensitivities of the six simulated TC characteristics to five model initial conditions: initial size and intensity of vortex seed, sea surface temperature, vertical lapse rate and mid-level relative humidity. The surrogate models are shown to successfully reproduce the response of CAM to changes in input conditions, and serve as powerful tools for quantifying numerous model input-output relationships with reduced computational burden. Finally, we examined the impact of parameterized physical processes on TC simulation and quantified the relative importance of 24 physical parameters on the six TC characteristics, respectively. The response function between TC characteristics and the associated most sensitive parameters are characterized. A group of ensemble simulations showed that the interactive effect among physical parameters greatly enlarges the uncertainty of simulated TC precipitation, LWCF, SWCF and IWP. Parameter uncertainty in simulated TC intensity is comparable to uncertainty resulting from changes in model initial conditions and model resolution. The Gaussian Spatial Process Model (GaSP) produced robust fits to CAM model responses in TC intensity, LWCF and SWCF, but experienced some difficulty reproducing TC precipitation rate, LWP and IWP.PhDAtmospheric, Oceanic and Space SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/133448/1/hefei_1.pd

Synthesis for circuit reliability

textElectrical and Computer Engineerin

Erasure Techniques in MRD codes

This book is organized into six chapters. The first chapter introduces the basic algebraic structures essential to make this book a self contained one. Algebraic linear codes and their basic properties are discussed in chapter two. In chapter three the authors study the basic properties of erasure decoding in maximum rank distance codes. Some decoding techniques about MRD codes are described and discussed in chapter four of this book. Rank distance codes with complementary duals and MRD codes with complementary duals are introduced and their applications are discussed. Chapter five introduces the notion of integer rank distance codes. The final chapter introduces some concatenation techniques.Comment: 162 pages; Published by Zip publishing in 201

Coding approaches to fault tolerance in dynamic systems

Also issued as Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (p. 189-196).Sponsored through a contract with Sanders, A Lockheed Martin Company.Christoforos N. Hadjicostis