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Digital hologram compression technique by eliminating spatial correlations based on MCTF

OPTICS COMMUNICATIONS 2010年第21期283卷 4261-4270页

作者： Seo, Young-Ho Choi, Hyun-Jun Yoo, Ji-Sang Lee, Gang-Seong Kim, Chung-Hyeok Lee, Seung-Hyun Lee, Sang-Hun Kim, Dong-Wook Kwangwoon Univ Coll Liberal Arts Seoul South Korea Kwangwoon Univ Dept Elect Engn Seoul South Korea Kwangwoon Univ Dept Elect Mat Engn Seoul South Korea Anyang Univ Dept Informat & Commun Engn Seoul South Korea

This paper proposed a new algorithm which compresses holographic signals captured or generated as digital data. A captured digital hologram is partitioned into multiple subregions with the same size. Next, if the Discrete Cosine Transform (DCT) is applied to these subregions, information that is visually similar to the original object is derived. Then the correlated subregions are organized into a single video stream and applied with Motion-Compensated Temporal Filtering (MCTF). Lastly, the streams are compressed using a lossy coding algorithm. This paper executed compression from 10:1 to 200:1 of digital holograms and observed the result after the reconstruction process. The numerical results represented about 11% increased compression efficiency compared to the previous researches. (C) 2010 Elsevier B.V. All rights reserved.

关键词： HOLOGRAPHY DIGITAL image processing COMPUTER algorithms coding theory DISCRETE cosine transforms NUMERICAL analysis

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Rewriting Codes for Joint Information Storage in Flash Memories

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IEEE TRANSACTIONS ON INFORMATION theory 2010年第10期56卷 5300-5313页

作者： Jiang, Anxiao (Andrew) Bohossian, Vasken Bruck, Jehoshua Texas A&M Univ Dept Comp Sci & Engn College Stn TX 77843 USA CALTECH Dept Elect Engn Pasadena CA 91125 USA

Memories whose storage cells transit irreversibly between states have been common since the start of the data storage technology. In recent years, flash memories have become a very important family of such memories. A flash memory cell has q states-state 0, 1, ... , q - 1-and can only transit from a lower state to a higher state before the expensive erasure operation takes place. We study rewriting codes that enable the data stored in a group of cells to be rewritten by only shifting the cells to higher states. Since the considered state transitions are irreversible, the number of rewrites is bounded. Our objective is to maximize the number of times the data can be rewritten. We focus on the joint storage of data in flash memories, and study two rewriting codes for two different scenarios. The first code, called floating code, is for the joint storage of multiple variables, where every rewrite changes one variable. The second code, called buffer code, is for remembering the most recent data in a data stream. Many of the codes presented here are either optimal or asymptotically optimal. We also present bounds to the performance of general codes. The results show that rewriting codes can integrate a flash memory's rewriting capabilities for different variables to a high degree.

关键词： coding theory data storage flash memory

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Monte Carlo simulation and measurements of clinical photon beams using LiF:Mg,Cu,P plus PTFE

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APPLIED RADIATION AND ISOTOPES 2010年第4-5期68卷 954-956页

作者： Azorin-Vega, C. Rivera-Montalvo, T. Azorin-Nieto, J. Villasenor-Navarro, L. Lujan-Castilla, P. Vega-Carrillo, H. IPN Ctr Invest Ciencia Aplicada & Tecnol Avanzada Mexico City 11500 DF Mexico Univ Autonoma Metropolitana Iztapalapa Mexico City 09340 DF Mexico Hosp Gen Mexico City Mexico City 06726 DF Mexico UAZ Unidad Acad Estudios Nucl Zacatecas 98000 Mexico

Thermoluminescent response of LiF:Mg,Cu,P+PTFE under clinical photon irradiation was obtained. Thermoluminescent dosimeters (TLDs) were irradiated for determining entrance surface dose (ESD) in a solid water phantom when using standard clinical adult treatment protocols. A Monte Carlo simulation of photon interaction with matter was performed and absorbed dose determined. ESD calculated by MCNPX code was greater than those determined by direct measurements in phantom. The results obtained open the possibility for using this material as a TLDs in medical accelerators. (C) 2009 Elsevier Ltd. All rights reserved.

关键词： MONTE Carlo method RADIATION measurements PROTON beams COMPUTER simulation THERMOLUMINESCENCE dosimetry coding theory LITHIUM compounds

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Mechanistic multidimensional analysis of horizontal two-phase flows

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NUCLEAR ENGINEERING AND DESIGN 2010年第2期240卷 405-415页

作者： Tselishcheva, Elena A. Antal, Steven P. Podowski, Michael Z. Rensselaer Polytech Inst Troy NY 12181 USA

The purpose of this paper is to discuss the results of analysis of two-phase flow in horizontal tubes. Two flow situations have been considered: gas/liquid flow in a long straight pipe, and similar flow conditions in a pipe with 90 degrees elbow. The theoretical approach utilizes a multifield modeling concept. A complete three-dimensional two-phase flow model has been implemented in a state-of-the-art computational multiphase fluid dynamics (CMFD) computer code, NPHASE. The overall model has been tested parametrically. Also, the results of NPHASE simulations have been compared against experimental data for a pipe with 90 degrees elbow. (C) 2009 Elsevier B.V. All rights reserved.

关键词： TWO-phase flow TUBES DIMENSIONAL analysis COMPUTATIONAL fluid dynamics coding theory PIPE SIMULATION methods & models

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Storage coding for Wear Leveling in Flash Memories

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IEEE TRANSACTIONS ON INFORMATION theory 2010年第10期56卷 5290-5299页

作者： Jiang, Anxiao (Andrew) Mateescu, Robert Yaakobi, Eitan Bruck, Jehoshua Siegel, Paul H. Vardy, Alexander Wolf, Jack K. Texas A&M Univ Dept Comp Sci & Engn College Stn TX 77843 USA Microsoft Res Cambridge Cambridge CB3 0FB England Univ Calif San Diego Ctr Magnet Recording Res La Jolla CA 92093 USA CALTECH Dept Elect Engn Pasadena CA 91125 USA Univ Calif San Diego Dept Elect & Comp Engn Dept Comp Sci & Engn La Jolla CA 92093 USA Univ Calif San Diego Dept Math La Jolla CA 92093 USA

Flash memory is a nonvolatile computer memory comprised of blocks of cells, wherein each cell is implemented as either NAND or NOR floating gate. NAND flash is currently the most widely used type of flash memory. In a NAND flash memory, every block of cells consists of numerous pages;rewriting even a single page requires the whole block to be erased and reprogrammed. Block erasures determine both the longevity and the efficiency of a flash memory. Therefore, when data in a NAND flash memory are reorganized, minimizing the total number of block erasures required to achieve the desired data movement is an important goal. This leads to the flash data movement problem studied in this paper. We show that coding can significantly reduce the number of block erasures required for data movement, and present several optimal or nearly optimal data-movement algorithms based upon ideas from coding theory and combinatorics. In particular, we show that the sorting-based (noncoding) schemes require O(n log n) erasures to move data among n blocks, whereas coding-based schemes require only O(n) erasures. Furthermore, coding-based schemes use only one auxiliary block, which is the best possible and achieve a good balance between the number of erasures in each of the n + 1 blocks.

关键词： coding theory combinatorics data storage flash memory graph theory wear leveling

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IET COMMUNICATIONS 2010年第10期4卷 1217-1225页

作者： Inamori, M. Nishimura, H. Sanada, Y. Ghavami, M. Keio Univ Dept Elect & Elect Engn Kohoku Ku Kanagawa 2238522 Japan Kings Coll London Div Engn UWB Commun Grp London WC2R 2LS England

Orthogonal frequency and code division multiplexing (OFCDM) has received large attention as a modulation scheme to realise high data rate transmission. The OFCDM system with fractional sampling (FS) is investigated. FS is a diversity scheme with a single antenna, which achieves path diversity through oversampling and parallel signal reception. However, the correlation among noise components may deteriorate the bit error rate performance at the receiver as the number of subcarriers and oversampling ratio increases. To overcome this problem, the alternative spreading code is used for the FS OFCDM system. Numerical results through computer simulation show that the proposed scheme can improve the performance of the receiver with the large oversampling ratio and the number of subcarriers.

关键词： ORTHOGONAL frequency division multiplexing CODE division multiple access BROADBAND communication systems coding theory COMPUTER simulation

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BREAKING THE ε-SOUNDNESS BOUND OF THE LINEARITY TEST OVER GF(2)

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SIAM JOURNAL ON COMPUTING 2010年第5期39卷 1988-2003页

作者： Kaufman, Tali Litsyn, Simon Xie, Ning MIT CSAIL Cambridge MA 02139 USA SUNY Buffalo Buffalo NY 14260 USA Tel Aviv Univ Dept Elect Engn Syst IL-69978 Tel Aviv Israel

For Boolean functions that are epsilon-far from the set of linear functions, we study the lower bound on the rejection probability (denoted by REJ(epsilon)) of the linearity test suggested by Blum, Luby, and Rubinfeld [J. Comput. System Sci., 47 (1993), pp. 549-595]. This problem is arguably the most fundamental and extensively studied problem in property testing of Boolean functions. The previously best bounds for REJ(epsilon) were obtained by Bellare et al. [IEEE Trans. Inform. theory, 42 (1996), pp. 1781-1795]. They used Fourier analysis to show that REJ(epsilon) >= epsilon for every 0 <= epsilon <= 1/2. They also conjectured that this bound might not be tight for epsilon's which are close to 1/2. In this paper we show that this indeed is the case. Specifically, we improve the lower bound of REJ(epsilon) >= epsilon by an additive constant that depends only on epsilon: REJ(epsilon) >= epsilon + min{1376 epsilon(3)(1-2 epsilon)(12), 1/4 epsilon(1-2 epsilon)(4)}, for every 0 <= epsilon <= 1/2. Our analysis is based on a relationship between REJ(epsilon) and the weight distribution of a coset code of the Hadamard code. We use both Fourier analysis and coding theory tools to estimate this weight distribution.

关键词： property testing linearity test coding theory Fourier analysis

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Weakly-Constrained Codes for Suppression of Patterning Effects in Digital Communications

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IEEE TRANSACTIONS ON COMMUNICATIONS 2010年第10期58卷 2845-2854页

作者： Shafarenko, Alexander Skidin, Anton Turitsyn, Sergei K. Univ Hertfordshire Sch Comp Sci Hatfield AL10 9AB Herts England SB RAS Inst Computat Technol Novosibirsk 630090 Russia Aston Univ Photon Res Grp Birmingham B4 7ET W Midlands England

We propose weakly-constrained stream and block codes with tunable pattern-dependent statistics and demonstrate that the block code capacity at large block sizes is close to the the prediction obtained from a simple Markov model published earlier. We demonstrate the feasibility of the code by presenting original encoding and decoding algorithms with a complexity log-linear in the block size and with modest table memory requirements. We also show that when such codes are used for mitigation of patterning effects in optical fibre communications, a gain of about 0.5dB is possible under realistic conditions, at the expense of small redundancy (approximate to 10%).

关键词： Patterning effects weakly-constrained codes coding theory pre-encoding

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Fast method for precoding and decoding of distributive multi-input multi-output channels in relay-based decode-and-forward cooperative wireless networks

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IET COMMUNICATIONS 2010年第2期4卷 144-153页

作者： Lee, M. H. Matalgah, M. M. Song, W. Chonbuk Natl Univ Inst Informat & Commun Jeonju 561756 South Korea Univ Mississippi Dept Elect Engn Ctr Wireless Commun University MS 38677 USA

It is well-known that the performance of the relay-based decode-and-forward (DF) cooperative networks outperforms the performance of the amplify-and-forward cooperative networks. However, this performance improvement is accomplished at the expense of adding more signal processing complexity (precoding/decoding) at each relay node. In this study, the authors tackle this signal processing complexity issue by proposing a Jacket-based fast method for reducing the precoding/decoding complexity in terms of time computation. Jacket transforms have shown to find applications in signal processing and coding theory. Jacket transforms are defined to be n x n matrices A = (a(jk)) over a field F with the property AA(dagger) nI(n), where A(dagger) is the transpose matrix of the element-wise inverse of A, that is, A(dagger) (a(kj)(-1)), which generalise Hadamard transforms and centre weighted Hadamard transforms. In particular, exploiting the Jacket transform properties, the authors propose a new eigenvalue decomposition (EVD) method with application in precoding and decoding of distributive multi-input multi-output channels in relay-based DF cooperative wireless networks in which the transmission is based on using single-symbol decodable space-time block codes. The authors show that the proposed Jacket-based method of EVD has significant reduction in its computational time as compared to the conventional-based EVD method. Performance in terms of computational time reduction is evaluated quantitatively through mathematical analysis and numerical results.

关键词： coding theory Communication system theory eigenvalue decomposition method Signal processing and detection Codes precoding weighted Hadamard transforms block codes Jacket transforms decoding channel coding Integral transforms in numerical analysis distributive multi-input multi-output channels precoding Hadamard transforms Signal processing theory signal processing complexity relay-based decode-and-forward cooperative networks eigenvalues and eigenfunctions signal processing conventional-based EVD method communication complexity computational time reduction distributive multi-input multi-output channels decoding

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Fault-tolerance techniques for hybrid CMOS/nanoarchitecture

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IET COMPUTERS AND DIGITAL TECHNIQUES 2010年第3期4卷 240-250页

作者： Melouki, A. Srivastava, S. Al-Hashimi, B. M. Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England

The authors propose two fault-tolerance techniques for hybrid CMOS/nanoarchitecture implementing logic functions as look-up tables. The authors compare the efficiency of the proposed techniques with recently reported methods that use single coding schemes in tolerating high fault rates in nanoscale fabrics. Both proposed techniques are based on error correcting codes to tackle different fault rates. In the. first technique, the authors implement a combined two-dimensional coding scheme using Hamming and Bose-Chaudhuri-Hocquenghem (BCH) codes to address fault rates greater than 5%. In the second technique, Hamming coding is complemented with bad line exclusion technique to tolerate fault rates higher than the. first proposed technique (up to 20%). The authors have also estimated the improvement that can be achieved in the circuit reliability in the presence of Don't Care Conditions. The area, latency and energy costs of the proposed techniques were also estimated in the CMOS domain.

关键词： NANOTECHNOLOGY COMPLEMENTARY metal oxide semiconductors ERROR-correcting codes (Information theory) coding theory DIGITAL electronics

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