Showing papers on "Concatenation published in 2004"

On sparse representations in arbitrary redundant bases

Abstract: The purpose of this contribution is to generalize some recent results on sparse representations of signals in redundant bases. The question that is considered is the following: given a matrix A of dimension (n,m) with m>n and a vector b=Ax, find a sufficient condition for b to have a unique sparsest representation x as a linear combination of columns of A. Answers to this question are known when A is the concatenation of two unitary matrices and either an extensive combinatorial search is performed or a linear program is solved. We consider arbitrary A matrices and give a sufficient condition for the unique sparsest solution to be the unique solution to both a linear program or a parametrized quadratic program. The proof is elementary and the possibility of using a quadratic program opens perspectives to the case where b=Ax+e with e a vector of noise or modeling errors.

Comparison of three methods for generating group statistical inferences from independent component analysis of functional magnetic resonance imaging data

Abstract: Purpose To evaluate the relative effectiveness of three previously proposed methods of performing group independent component analysis (ICA) of functional magnetic resonance imaging (fMRI) data. Materials and Methods Data were generated via computer simulation. Components were added to a varying number of subjects between 1 and 20, and intersubject variability was simulated for both the added sources and their associated time courses. Three methods of group ICA analyses were performed: across-subject averaging, subject-wise concatenation, and row-wise concatenation (e.g., across time courses). Results Concatenating across subjects provided the best overall performance in terms of accurate estimation of the sources and associated time courses. Averaging across subjects provided accurate estimation (R > 0.9) of the time courses when the sources were present in a sufficient fraction (about 15%) of 100 subjects. Concatenating across time courses was shown not to be a feasible method when unique sources were added to the data from each subject, simulating the effects of motion and susceptibility artifacts. Conclusion Subject-wise concatenation should be used when computationally feasible. For studies involving a large number of subjects, across-subject averaging provides an acceptable alternative and reduces the computational load. J. Magn. Reson. Imaging 2004;19:365–368. © 2004 Wiley-Liss, Inc.

Real-time error protection of embedded codes for packet erasure and fading channels

Abstract: Reliable real-time transmission of packetized embedded multimedia data over noisy channels requires the design of fast error control algorithms. For packet erasure channels, efficient forward error correction is obtained by using systematic Reed-Solomon (RS) codes across packets. For fading channels, state-of-the-art performance is given by a product channel code where each column code is an RS code and each row code is a concatenation of an outer cyclic redundancy check code and an inner rate-compatible punctured convolutional code. For each of these two systems, we propose a low-memory linear-time iterative improvement algorithm to compute an error protection solution. Experimental results for the two-dimensional and three-dimensional set partitioning in hierarchical trees coders showed that our algorithms provide close to optimal average peak signal-to-noise ratio performance, and that their running time is significantly lower than that of all previously proposed solutions.

Range concatenation grammars

Abstract: We present Range Concatenation Grammars, a syntactic formalism which possesses many attractive features, among which we emphasize here generative capacity and closure properties. For example, Range Concatenation Grammars have stronger generative capacity than Linear Context-Free Rewriting Systems, although this power is not to the detriment of efficiency, since the generated languages can always be parsed in polynomial time. Range Concatenation Languages are closed under both intersection and complementation, and these closure properties suggest novel ways to describe some linguistic phenomena. We also present a parsing algorithm which is the basis for our current prototype implementation.

Join cost for unit selection speech synthesis

Abstract: In unit-selection speech synthesis systems, synthetic speech is produced by concatenating speech units selected from a large database, or inventory, which contains many instances of each speech unit with varied prosodic and spectral characteristics. Hence, by selecting an appropriate sequence of units, it is possible to synthesize highly natural-sounding speech. The selection of the best unit sequence from the database is typically treated as a search problem in which the best sequence of candidates from the inventory is the one that has the lowest overall cost [1]. This cost is often decomposed into two costs: a target cost (how closely candidate units in the inventory match the specification of the target phone sequence) and join cost (how well neighboring units can be joined) [1]. If, as is usually the case, the cost functions used to compute these costs take into account only properties of the fixed target sequence and local properties of the candidates, the optimal unit sequence can be found efficiently by a Viterbi search for the lowest cost path through the lattice of the target and join costs. In this chapter we focus on the calculation of the join cost (also known as concatenation cost). The ideal join cost is one that, although based solely on measurable properties of the candidate units—such as spectral parameters, amplitude, and F0—correlates highly with human listeners’ perceptions of discontinuity at concatenation points. In other words, the join cost should predict the degree of perceived discontinuity. We use this terminology: a join cost is computed using a join cost function, which generally uses a distance measure on some parameterization of the speech signal.

Concatenation and piggyback mechanisms for the IEEE 802.11 MAC

Abstract: The IEEE 802.11 medium access control (MAC) is a very robust protocol for the best-effort service in the wireless medium. However, many studies have been reported that it is not very efficient. One of the fundamental problems of MAC inefficiency is overhead. In this paper, we propose two novel mechanisms to reduce overhead of the IEEE 802.11 protocols: a concatenation mechanism and a piggyback mechanism. Performance analysis is conducted with simulations. Studies show that both proposed schemes have greatly improved the system performance.

State complexity of concatenation and complementation of regular languages

Abstract: We investigate the state complexity of concatenation and the nondeterministic state complexity of complementation of regular languages. We show that the upper bounds on the state complexity of concatenation are also tight in the case that the first automaton has more than one accepting state. In the case of nondeterministic state complexity of complementation, we show that the entire range of complexities, up to the known upper bound can be produced.

Statistical Modeling for Unit Selection in Speech Synthesis

Abstract: Traditional concatenative speech synthesis systems use a number of heuristics to define the target and concatenation costs, essential for the design of the unit selection component. In contrast to these approaches, we introduce a general statistical modeling framework for unit selection inspired by automatic speech recognition. Given appropriate data, techniques based on that framework can result in a more accurate unit selection, thereby improving the general quality of a speech synthesizer. They can also lead to a more modular and a substantially more efficient system.We present a new unit selection system based on statistical modeling. To overcome the original absence of data, we use an existing high-quality unit selection system to generate a corpus of unit sequences. We show that the concatenation cost can be accurately estimated from this corpus using a statistical n-gram language model over units. We used weighted automata and transducers for the representation of the components of the system and designed a new and more efficient composition algorithm making use of string potentials for their combination. The resulting statistical unit selection is shown to be about 2.6 times faster than the last release of the AT&T Natural Voices Product while preserving the same quality, and offers much flexibility for the use and integration of new and more complex components.

Method for statistical language modeling in speech recognition

Abstract: A system for generating language modeling data for a speech recognition system includes an expression extractor to extract expression from domain-specific data of an existing domain using a base of linguistic knowledge, a concept structure mapper to map extractedexpression to expression in a new domain using vocabulary for the new domain, a concatenation module to concatenate extracted expression with domain-general data, and a filter arrangement to identify and filter out unrealistic expression in the mapped or concatenated expression.

Self-adaptive prefix encoding for stable node identifiers

Abstract: A variable-length binary string is utilized to encode node identifiers in a tree for an XML document object model. A general prefix encoding scheme is followed; a node identifier is generated by the concatenation of encodings at each level of a tree along a path from a root node to another particular node. Arbitrary insertions are supported without change to existing node identifier encodings. In addition, the method provides for document order when unsigned binary string comparison is used to compare encoded node identifiers. In support of sub-document concurrency control, prefix encoding provides a way to derive ancestor-descendant relationships among nodes in a tree. Lastly, the encoding method provides a natural pre-order clustering sequence, also known as depth-first clustering. If a prefix is applied to an encoding with a level number, starting with zero at the root, width-first clustering will result. A mixed clustering can also be supported.

Visibly Pushdown Expression Effects for XML Stream Processing

Abstract: We define an effect system, based upon visibly pushdown languages (VPLs), for a programming language that processes streams of tokens with parenthesis-like matching, as found in XML documents or s-expressions. The effect analysis ensures that programs read and write words in which tokens match, despite the fact that tokens are read and written individually. In particular, the novel treatment of input provides a compositional description of the behaviour of programs with lookahead. We introduce visibly pushdown expressions (VPEs), corresponding to the class of VPLs, as the effects. VPEs generalize regular expression types by incorporating intersection, unmatched tokens, and overlapped concatenation (used in the analysis of operations with lookahead). Hosoya, Vouillon, and Pierce’s decision procedure for language inclusion between regular expression types, via a translation to non-deterministic tree automata, does not apply to VPEs. Instead we obtain a decision procedure via a translation of VPEs to Alur and Madhusudan’s monadic second order logic with matching relation MSOμ.

Error correction encoding/decoding apparatus and error correction encoding/decoding method

Abstract: An error correction coding apparatus which improves the throughput of the whole system, while minimizing the increase of the circuit size and the amount of processing operation of the whole apparatus. In this apparatus, a data divider 132 divides transmission data into a plurality of blocks to generate n divided blocks. The n error correction coders out of N error correction coders 134 carry out an error correction coding on each of the n divided blocks in units of block, and outputs the divided blocks. A data concatenator 136 concatenates the n code blocks that have been error-correction-coded in units of block. A division/concatenation controller 138 controls at least one of data divider 132 and data concatenator 136 so that the division of the transmission data and the concatenation of the code blocks are carried out in units of bit.

Speech synthesis apparatus and method, and storage medium

Abstract: Input text data undergoes language analysis to generate prosody, and a speech database is searched for a synthesis unit on the basis of the prosody. A modification distortion of the found synthesis unit, and concatenation distortions upon connecting that synthesis unit to those in the preceding phoneme are computed, and a distortion determination unit weights the modification and concatenation distortions to determine the total distortion. An Nbest determination unit obtains N best paths that can minimize the distortion using the A* search algorithm, and a registration unit determination unit selects a synthesis unit to be registered in a synthesis unit inventory on the basis of the N best paths in the order of frequencies of occurrence, and registers it in the synthesis unit inventory.

Regular Language Matching and Other Decidable Cases of the Satisfiability Problem for Constraints between Regular Open Terms

Abstract: In this work, we investigate computational complexity of the solution existence problem for language equations and language constraints. More accurately, we study constraints between regular terms over alphabet consisting of constants and variables and based on regular operators such as concatenation (·), sum (+), Kleene-star (*). We obtain complexity results concerning three restricted cases of the constraints: for system of language equations in which one side does not contain any occurrences of variables in case arbitrary solutions and with restriction to finite languages; for constraint in form L ⊆ R, where R has no occurrences of variables.

Trajectory-based operations

Abstract: Shuffle on trajectories was introduced by Mateescu et al. [147] as a method of generalizing several studied operations on words, such as the shuffle, concatenation and insertion operations. This natural construction has received significant and varied attention in the literature. In this thesis, we consider several unexamined areas related to shuffle on trajectories. We first examine the state complexity of the shuffle on trajectories. We find that the density of the set of trajectories is an appropriate measure of the complexity of the associated operation, since low density sets of trajectories yield less complex operations. We introduce the operation of deletion along trajectories, which serves as an inverse to shuffle on trajectories. The operation is also of independent interest, and we examine its closure properties. The study of deletion along trajectories also leads to the study of language equations and systems of language equations with shuffle on trajectories. The notion of shuffle on trajectories also has applications to the theory of codes. Each shuffle on trajectories operation defines a class of languages. Several of these language classes are important in the theory of codes, including the prefix-, suffix-, biprefix-codes and the hypercodes. We investigate these classes of languages, decidability questions, and related binary relations. We conclude with results relating to iteration of shuffle and deletion on trajectories. We characterize the smallest language closed under shuffle on trajectories or deletion along trajectories, as well as generalize the notion of primitive words and primitive roots. Further examination of language equations are also possible with the iterated counterparts of shuffle and deletion along trajectories.

Type inference for record concatenation and subtyping

Abstract: Record concatenation, multiple inheritance, and multiple-object cloning are closely related and part of various language designs. For example, in Cardelli's untyped Obliq language, a new object can be constructed from several existing objects by cloning followed by concatenation; an error is given in case of field name conflicts. Type systems for record concatenation have been studied by Wand, Harper and Pierce, Remy, and others; and type inference for the combination of record concatenation and subtyping has been studied by Sulzmann and by Pottier. In this paper we present a type inference algorithm for record concatenation, subtyping, and recursive types. Our example language is the Abadi-Cardelli object calculus extended with a concatenation operator. Our algorithm enables type checking of Obliq programs without changing the programs at all. We prove that the type inference problem is NP-complete.

Multichannel fusion models for the parametric classification of multicategory differential brain activity

Abstract: This work introduces multichannel classification fusion and multichannel data fusion models to fully exploit the different but complementary brain activity information recorded from multiple channels. The goal is to accurately classify differential brain activity into their respective categories. A parametric weighted classification fusion model and three weighted data fusion models (mixture, sum, and concatenation) are introduced. Parametric classifiers are developed for each fusion strategy and the performances of the different strategies are compared by classifying 14-channel evoked potentials (EPs) collected from subjects involved in making explicit match/mismatch comparisons between sequentially presented stimuli. The best performance is obtained using multichannel EP concatenation and the performance improves by incorporating weights in the fusion rules. The fusion strategies introduced are also applicable to other problems involving the classification of multicategory multivariate signals generated from multiple sources.

Routing in Turn-Prohibition Based Feed-Forward Networks

Abstract: The application of queuing theory to communications systems often requires that the respective networks are of a feed-forward nature, that is they have to be free of cyclic dependencies. An effective way to ensure this property is to identify a certain set of critical turns and to prohibit their use. A turn is a concatenation of two adjacent, consecutive links.

Grammatical Constant Creation

Abstract: This study examines the utility of grammatical ephemeral random constants, and conducts an analysis of the preferences of evolutionary search when a number of different grammar based constant generation methods are provided with Grammatical Evolution. Three constant generation techniques are supplied, namely, grammatical ephemeral random constants, digit concatenation, and an expression based approach. A number of constant generation problems are tackled to analyse this approach, with results indicating a preference for both the digit concatenation and grammatical ephemeral random constants. The provision of different constant generation strategies allowing the evolutionary process to automatically determine which technique to adopt would, therefore, appear to be advantageous.

Turbo encoding and decoding of Reed-Solomon codes through binary decomposition and self-concatenation

Abstract: This paper presents a two-stage turbo-coding scheme for Reed-Solomon (RS) codes through binary decomposition and self-concatenation. In this scheme, the binary image of an RS code over GF(2/sup m/) is first decomposed into a set of binary component codes with relatively small trellis complexities. Then the RS code is formatted as a self-concatenated code with itself as the outer code and the binary component codes as the inner codes in a turbo-coding arrangement. In decoding, the inner codes are decoded with turbo decoding and the outer code is decoded with either an algebraic decoding algorithm or a reliability-based decoding algorithm. The outer and inner decoders interact during each decoding iteration. For RS codes of lengths up to 255, the proposed two-stage coding scheme is practically implementable and provides a significant coding gain over conventional algebraic and reliability-based decoding algorithms.

Serial/parallel (S/P) turbo codes for low error rates

Abstract: This article describes a new concatenation scheme for turbo codes, a hybrid model between serial and parallel turbo codes, which offers improved asymptotic performance. We review the classical regular interleaving problems and we show how this new hybrid model allows us to keep a simple regular interleaving while outperforming more complex permutations at low error rates. Simulation results are presented and compared with well established turbo codes.

Reliable transmission with low complexity Reed-Solomon block turbo codes

Abstract: We show here that low complexity Reed-Solomon (RS) block turbo codes (BTC) based on Q-ary symbol and bit concatenation can both achieve reliable transmission at less than 1 dB from Shannon limit using quadrature phase shift keying (QPSK) over additive white Gaussian noise (AWGN) channel. These near Shannon performances are due to a proper choice of RS component codes in the construction of RS product codes. RS-BTC based on Q-ary symbol concatenation has a great advantage in terms of block size over those based on bit concatenation. Compared to Bose-Chaudhuri-Hocquenghem (BCH) BTC of similar code rate, its smaller memory size is worth noting from the practical point of view.

Asynchronous, quasi-Adiabatic (Asynchrobatic) logic for low-power very wide data width applications

Abstract: A new "Asynchrobatic" low-power logic design style is presented. Its name is a shortening of the concatenation of the two fields of low-power research that it attempts to join. It uses the low-power benefits of an Asynchronous controller to drive a wide data-path of quasi-Adiabatic elements. Results show that in applications with a high switch rate, for example DSP, it is more efficient than a 32-bit asynchronous data-path. It also becomes more efficient as data-path widths are increased.

Phoxsy: multi-phone segments for unit selection speech synthesis.

Abstract: A multi-phone unit specification for unit selection speech synthesis is introduced and tested with regard to its qualitative aspects by means of a listening experiment This different concept of unit definition aims to prevent spectral discontinuities at highly critical points of concatenation and to allow for a faster creation of speech corpora, as well as a speed-up of cost calculation and unit selection at run time The new units called phoxsy have been designed for German, but the concept can be easily extended to other languages and may also serve as a basis for new half-phone-like segments

Chapter 12 – Turbo Codes

Abstract: Publisher Summary This chapter deals with turbo codes, one of the most powerful types of forward-error-correcting channel codes. It discusses the underlying concepts and presents a description and comparison of the turbo codes used by the Universal Mobile Telecommunications System (UMTS) and cdma2000 third-generation cellular systems. Forward-error-correcting (FEC) channel codes are commonly used to improve the energy efficiency of wireless communication systems. By the end of the 1990s, the virtues of turbo codes were well known, and they began to be adopted in various systems. One of the most interesting characteristics of a turbo code is that it is not just a single code. This chapter illustrates the performance of the turbo codes used by the two third-generation cellular standards. Although turbo codes have the potential to offer unprecedented energy efficiencies, they have some peculiarities, which result in error flooring. A way to reduce the error floor is to arrange the two constituent encoders in a serial concatenation, rather than in a parallel concatenation. One solution to the synchronization problems is to incorporate the synchronization process into the iterative feedback loop of the turbo decoder itself.

Robust wireless transmission of regions of interest in JPEG2000

Abstract: In this paper, we present a technique to robustly transmit regions of interest in the JPEG2000 framework. The technique assumes a prioritized region-of-interest coding and optimally assigns channel protection to the coded data according to the importance of every packet in the final bit-stream. The mean energy of the transform coefficients contained in a packet and the distance of a packet from the region of interest determine the importance of every packet. The channel protection is achieved by means of a concatenation of a cyclic redundancy check outer coder and an inner rate-compatible convolutional coder. Simulation results performed over a Rayleigh fading channel show an improvement in the visual quality of the reconstructed images.

Camera-typing interface for ubiquitous information services

Abstract: We propose a new technology called the camera-typing interface, which can read printed characters such as URLs with a low-resolution camera. It realizes a type of ubiquitous information service using smart phones with cameras. This method includes two main advantages: automatic concatenation of sequential shots and automatic error correction by re-shooting. The automatic concatenation enables a user to take segmented images of a character string, thus a low-resolution camera can be used as the interface device. The automatic error correction enables the user to correct misrecognized characters just by retaking images around them, providing an easy and natural way of error correction. We present two experimental results to prove effectiveness of our method. Both results indicate that our proposed method is helpful.

Method and device for virtual concatenation transmission

Abstract: In a method and a device for virtual concatenation transmission which multiplex traffics of low-speed frames into a high-speed frame based on a virtual concatenation, a virtual concatenation with an excellent transmission efficiency is provided. Specifically, in order to provide the transmission method and the device which do not waste channels, require little labor of operators, do not cause an instantaneous interruption, and require no memory capacity, a plurality of low-speed frames are multiplexed into arbitrary positions within a high-speed frame to compose a virtual concatenation, and are transmitted together with virtual concatenation information indicating a concatenation state of positions of the low-speed frames, with a phase relationship being maintained.

Subjective Evaluation of Join Cost Functions Used in Unit Selection Speech Synthesis

Abstract: In our previous papers, we have proposed join cost functions derived from spectral distances, which have good correlations with perceptual scores obtained for a range of concatenation discontinuities. To further validate their ability to predict concatenation discontinuities, we have chosen the best three spectral distances and evaluated them subjectively in a listening test. The unit sequences for synthesis stimuli are obtained from a state-of-the-art unit selection text-to-speech system: rVoice from Rhetorical Systems Ltd. In this paper, we report listeners' preferences for each of the three join cost functions.