An error-correcting code is said to be locally decodable if a randomized algorithm can recover any single bit of a message by reading only a small number of symbols of a possibly corrupted encoding of the message. Katz and Trevisan (On the efficiency of local decoding procedures for error correcting codes, STOC 2000, 80–86) showed that any such code C : {0, 1}n → Σ with a decoding algorithm tha...

CELP coders using pulse codebooks for excitations such as ACELP[1] have the advantages of low complexity and high speech quality. At low bit rates, however, the decrease of pulse position candidates and the number of pulses degrades reconstructed speech quality. This paper describes a method for adaptive allocating of pulse position candidates. In the proposed method, N e cient candidates of pu...

In this paper, analysis of an adaptive rate convolutionally coded multicarrier direct sequence code division multiple-access (DS/CDMA) system is considered. In order to accommodate a number of coding rates easily and make the encoder and decoder structure simple, we use the rate-compatible punctured convolutional (RCPC) code. We obtain data throughputs at several coding rates, and choose the co...

Characterizing performance is essential to optimize programs and architectures. The open source Adaptive Sampling Kit (ASK) measures the performance trade-off in large design spaces. Exhaustively sampling all sets of parameters is computationally intractable. Therefore, ASK concentrates exploration in the most irregular regions of the design space through multiple adaptive sampling strategies. ...

A linear kinetic stability code for tokamak plasmas: AEGIS-K (Adaptive EiGenfunction Independent Solutions-Kinetic), is described. The AEGIS-K code is based on the newly developed gyrokinetic theory [L.J. Zheng, M.T. Kotschenreuther, J.W. Van Dam, Phys. Plasmas 14 (2007) 072505]. The success in recovering the ideal magnetohydrodynamics (MHD) from this newly developed gyrokinetic theory in the p...

A multilevel method on adaptive meshes with hanging nodes is derived. Smoothing is restricted to the interior of the subdomains refined to the current level, thus has optimal computational complexity. Its convergence rates are the same as for the the non-adaptive version. We discuss the implementation in a general finite element code at the example of the deal.II library.

Chain codes are the most size-efficient representations of rasterised binary shapes and contours. This paper considers a new lossless chain code compression method based on move-to-front transform and an adaptive run-length encoding. The former reduces the information entropy of the chain code, whilst the latter compresses the entropy-reduced chain code by coding the repetitions of chain code s...

Partial diierential equations can be solved eeciently by adaptive multigrid methods on a parallel computer. We report on the concept of hash-table storage techniques to set up such a code. The code requires substantial less amount of memory and is easier to code in the sequential case. The parallelization takes place by a space lling curve domain decomposition intimately connected to the hash t...

In this paper, we describe a structured variable length coding (VLC) based on Golomb code that generalize the current context-based adaptive variable length coding (CAVLC) in the emerging video coding standard H.264/AVC. The current CAVLC is characterized as unstructured VLC and uses extensive dedicated code tables. Lack of generality due to these code tables causes a problem of over-fitting or...

An image processing algorithm to detect visual code markers and extract the embedded data is presented. The algorithm uses an adaptive thresholding technique to produce a binary image with an accurate representation of each visual code marker from an input RGB image. Visual code marker detection is performed on the binary image using a series of tests that leverage prior knowledge of the distin...