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Journal of Shanghai University(English Edition) 2011年第3期15卷 194-200页

作者：金超冯丹刘景宁 Wuhan National Laboratory for Optoelectronics School of Computer Science and Technology Huazhong University of Science and Technology

x-code is one of the most important redundant array of independent disk （RAID）-6 codes which are capable of tolerating double disk failures. However, the code length of x-code is restricted to be a prime number, and such code length restriction of x-code limits its usage in the real storage systems. Moreover, as a vertical RAID-6 code, x-code can not be extended easily to an arbitrary code length like horizontal RAID-6 codes. In this paper, a novel and efficient code shortening algorithm for x-code is proposed to extend x-code to an arbitrary length. It can be further proved that the code shortening algorithm maintains the maximum-distance-separable （MDS） property of x-code, and namely, the shortened x-code is still MDS code with the optimal space efficiency. In the context of the shortening algorithm for x-code, an in-depth performance analysis on x-code at consecutive code lengths is conducted, and the impacts of the code shortening algorithm on the performance of x-code in various performance metrics are revealed.

关键词： redundant array of independent disk (RAID)-6 x-code vertical code code shortening performance analysis

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x-code+: A Compromised Coding Scheme with Smaller Rebuild Window and Load-balance

X-Code+: A Compromised Coding Scheme with Smaller Rebuild Wi...

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International Conference on Computer Science and Network Technology

作者： Mingzhu Deng Lingyu Zhu Nong xiao Zhiguang Chen Fang Liu State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha China

ISBN: (纸本)9781467381741

Modern storage systems call for higher reliability care beyond RAID-6 against ever-increasing data failures. And no code extension exist based on x-code, which is noted for vertical alignment and optimal update complexity. In order to construct flexible and practically reliable codes, we argue that failures happen successively and higher-level failures can be degraded into separate lower-level failures with shorter rebuilding time. Therefore, we present x-code+, a fast recoverable coding scheme by explicitly modifying and extending x-code. We modify the original x-code by redistributing elements to keep a base reliability for double-failure and further extend it with two-element tuples in one extra parity drive to shorten rebuild windows and degrade complex failure scenarios. Analysis shows that x-code+ has better recovery performance and load-balance and less update penalty than its peer codes.

关键词： x-code code extension failure degradation recovery speedup load-balance Load balancing Degradation failures Cache Memory System mechanical heart valve RAID labeling scheme penalty failures windows windows

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The Design and Implementation of tourism APP Based on x-code

The Design and Implementation of tourism APP Based on X-Code

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2017 International Seminar on Social Science and Humanities Research

作者： Shi-jun Yang Ning Wei College of Computer and Information Technology China Three Gorges University

This topic mainly explains the application about travel through x-code development *** APP provide some advice to *** main content of this article explain how to implement the *** works studied different user require such as framework, function and the final *** application also shared social media including third-party login and sharing.

关键词： Object-C language The mobile Internet Tourism x-code

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基于x-code的银联移动支付系统的研究与设计

基于X-code的银联移动支付系统的研究与设计

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作者：李威昆明理工大学

学位级别：硕士

随着移动电子设备及移动高速网络的的快速发展,大众开始接触移动电子商务。伴随着移动电子商务的快速发展,大众开始使用移动支付系统。移动支付系统即移动电子设备利用无线网络完成所购商品或服务的一种支付方式。这种支付方式作为下一... 详细信息

随着移动电子设备及移动高速网络的的快速发展,大众开始接触移动电子商务。伴随着移动电子商务的快速发展,大众开始使用移动支付系统。移动支付系统即移动电子设备利用无线网络完成所购商品或服务的一种支付方式。这种支付方式作为下一代支付的主要手段,为人们网上购物提供了便利。客户通过手机浏览网页,选择所需商品,对所需商品进行付费。这种支付方式与传统的支付方式进行比较,其特点在于支付方式灵活、支付场所不受限制,为用户减少处理时间及其他不必要的麻烦。与此同时,为银行业务增长、商家的利润增长提供了新的空间。此项目具有非常大的经济价值。本篇论文进行了如下工作： 1.绪论部分,简单介绍了近些年国内外移动支付系统发展的现状,课题研究的目的、本文的工作内容等。 2.介绍移动支付的受理模式。本章首先对移动支付的基础概念进行讲解,然后分析移动支付的处理流程,介绍了移动支付的特征。 3.简介x-code软件及其开发环境,分析IOS技术构架,简单说明了Web服务的概念及其功能,对比Web和Wap的区别,简述Wap优点及局限性。展望Web服务的发展趋势。 4.介绍新型移动支付系统的提出及Web平台的实现。首先进行系统概述,简述银联商圈结构及支付系统构架,系统采用MVC构架,有利于更新与升级。提出了利用“黑箱”理论强化IPhone端与服务器端数据传输的安全性,进而提高系统的安全性。 5.根据上述理论,以银联移动支付接口作为基础,利用现有设备搭载银联移动支付系统环境,实现基于x-code的IPhone在线移动交费系统,验证系统的可用性。 6.总结与展望。对论文结束之后还需改进的地方进行总结,对以后所需做的工作进行展望。

关键词： x-code 移动支付 Web服务安全支付银联移动支付接口

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中间语言x-code的设计思想

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计算机学报 1983年第2期 99-108页

作者：胡燕武白光野中国科学院计算中心中国科学院计算技术研究所

“软件移植”是目前国际上软件研究的一个重要课题。我们提出了移植系统程序设计语言xCY的中间语言x-code方案。希望通过xCY语言的移植,最终实现系统软件的移植。我们在两种不同类型的计算机上实现了x-code编译程序。本文对x-code的设... 详细信息

“软件移植”是目前国际上软件研究的一个重要课题。我们提出了移植系统程序设计语言xCY的中间语言x-code方案。希望通过xCY语言的移植,最终实现系统软件的移植。我们在两种不同类型的计算机上实现了x-code编译程序。本文对x-code的设计进行了较详细的阐述。

关键词：中间语言系统程序设计语言程序语言复合对象 x-code 设计思想

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Bounds on Separating Redundancy of Linear codes and Rates of x-codes

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IEEE TRANSACTIONS ON INFORMATION THEORY 2018年第12期64卷 7577-7593页

作者： Tsunoda, Yu Fujiwara, Yuichiro Ando, Hana Vandendriessche, Peter Chiba Univ Grad Sch Sci & Engn Chiba 2638522 Japan Chiba Univ Div Math & Informat Chiba 2638522 Japan Nomura Res Inst Digital Platform Div Tokyo 1350042 Japan Univ Ghent Dept Math B-9000 Ghent Belgium

An error-erasure channel is a simple noise model that introduces both errors and erasures. While the two types of errors can be corrected simultaneously with error-correcting codes, it is also known that any linear code allows for first correcting errors and then erasures in two-step decoding. In particular, a carefully designed parity-check matrix not only allows for separating erasures from errors but also makes it possible to efficiently correct erasures. The separating redundancy of a linear code is the number of parity-check equations in a smallest parity-check matrix that has the required property for this error-erasure separation. In a sense, it is a parameter of a linear code that represents the minimum overhead for efficiently separating erasures from errors. While several bounds on separating redundancy are known, there still remains a wide gap between upper and lower bounds except for a few limited cases. In this paper, using probabilistic combinatorics and design theory, we improve both upper and lower bounds on separating redundancy. We also show a relation between parity-check matrices for error-erasure separation and special matrices, called x-codes, for data compaction circuits in VLSI testing. This leads to an exponentially improved bound on the size of an optimal x-code.

关键词： Linear code error-erasure channel separating redundancy probabilistic method covering combinatorial design x-code x-compact

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A Combinatorial Approach to x-Tolerant Compaction Circuits

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IEEE TRANSACTIONS ON INFORMATION THEORY 2010年第7期56卷 3196-3206页

作者： Fujiwara, Yuichiro Colbourn, Charles J. Michigan Technol Univ Dept Math Sci Houghton MI 49931 USA Arizona State Univ Sch Comp Informat & Decis Syst Engn Tempe AZ 85287 USA

Test response compaction for integrated circuits (ICs) with scan-based design-for-testability (DFT) support in the presence of unknown logic values (xs) is investigated from a combinatorial viewpoint. The theoretical foundations of x-codes, employed in an x-tolerant compaction technique called x-compact, are examined. Through the formulation of a combinatorial model of x-compact, novel design techniques are developed for x-codes to detect a specified maximum number of errors in the presence of a specified maximum number of unknown logic values, while requiring only small fan-out. The special class of x-codes that results leads to an avoidance problem for configurations in combinatorial designs. General design methods and nonconstructive existence theorems to estimate the compaction ratio of an optimal x-compactor are also derived.

关键词： Built-in self-test (BIST) circuit testing compaction configuration Steiner system superimposed code test compression x-code x-compact

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Design of an Intelligent Reflecting Surface Aided mmWave Massive MIMO Using x-Precoding

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IEEE ACCESS 2022年 10卷 69428-69440页

作者： Li, Jiarui Hong, Yi Monash Univ Dept Elect & Comp Syst Engn Melbourne Vic 3800 Australia

In this paper, we consider an intelligent reflecting surface (IRS) aided millimeter wave (mmWave) massive multiple-input multiple-output (MIMO) system using hybrid beamforming/combining. To enhance error performance, we adopt x-code (or x-precoder), a low-complexity precoding technique for traditional MIMO channels, to encode information symbols. We first derive an upper bound on word error rate (WER), based on which we design jointly IRS phase shifts and x-code (or x-precoder) to minimize WER. Specifically, we propose two algorithms for IRS design exploiting alternating optimization and gradient ascent optimization methods. Then we devise x-code and x-precoder, respectively, by minimizing average WER over all channel realizations and WER for each channel realization. We also provide their diversity analysis. Further, we present the procedure of decoupling fully digital beamformer/combiner at transceiver into the optimal hybrid one. Finally, simulation results show that both IRS optimization algorithms have similar WERs whereas gradient ascent approach has a lower computational complexity. Simulations demonstrate that the designed x-code (or x-precoder) provides a significant performance gain.

关键词： Radio frequency Precoding Massive MIMO Symbols Array signal processing Computational complexity Surface waves Diversity intelligent reflecting surface (IRS) massive multiple-input multiple output (MIMO) millimeter wave (mmWave) precoding word error rate x-code x-precoder

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The Performance Of Erasure codes Used In FT-MPI

The Performance Of Erasure Codes Used In FT-MPI

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International Forum on Information Technology and Applications (IFITA 2009)

作者： Liu xiaoguang Wang Gang Zhang Yu Li Ang xie Fang Nankai Univ Coll Informat Nankai Baidu Joint Lab Tianjin 300071 Peoples R China Hubei Univ Technol Coll Comp Sci Wuhan 430068 Peoples R China

ISBN: (纸本)9780769536002

Today, the scale of High performance computing (HPC) systems is much larger than ever. Some HPC systems consist of thousands or even tens of thousands of processors. The larger scale leads to a challenge that how to deal with process failures. The most important programming tool for HPC is MPI (Message Passing Interface). There are some existing methods to deal with fault-tolerance, such as MPICH-V, StarFish, MPI/FT and so on, using the MPI context. Most of them do the checkpoint on disk. In this paper, some erasure codes, which used in RAID systems usually, are applied to deal with the fault-tolerance in-memory. Based on fault-tolerance-MPI (FT-MPI) platform, RAID4, RAID5, RDP and x-code are implanted to do the checkpoint in-memory. The experimental results show that RDP is feasible for double-fault-tolerance in-memory.

关键词： MPI fault-tolerance RDP x-code

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SCAN: An Efficient Decoding Algorithm for RAID-6 codes

SCAN: An Efficient Decoding Algorithm for RAID-6 Codes

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10th IEEE International Symposium on Network Computing and Applications (NCA)

作者： Luo, Jianqiang xu, Lihao Wayne State Univ Dept Comp Sci Detroit MI 48202 USA

ISBN: (纸本)9780769544892

Recent studies show hard disk drives fail much more often in real systems than specified in their data-sheets, and RAID-5 may not be able to provide necessary reliability for practical systems. It is desirable to have disk arrays and clustered storage systems with higher data redundancy, such as RAID-6. Meanwhile, latest research also indicates that sector failures become a threat to data reliability in storage systems. As a result, disk failures in RAID-6 systems become complex, and call for efficient decoding approaches to recover data when disk failures take place. This paper proposes a simple and efficient decoding algorithm to reconstruct data from disk failures for RAID-6 systems. First, for many well known RAID-6 codes, we provide the conditions to determine the recoverability of disk failures by using Tanner graph. The covered RAID-6 codes include x-code, EVENODD, and RDP. Then, a generic failure decoding algorithm called SCAN algorithm is derived. The SCAN algorithm is able to efficiently reconstruct data for any recoverable disk failures. Extensive performance evaluation shows the SCAN algorithm achieves higher performance than Matrix Method, another general decoding algorithm. Hence, the SCAN algorithm is an attractive decoding algorithm to be integrated into RAID-6 systems.

关键词： Algorithm design and analysis Decoding EVENODD Encoding Equations Iterative decoding RAID RAID-6 codes RDP Reliability SCAN algorithm Tanner graph x-code clustered storage system data reconstruction data recovery data reliability decoding decoding algorithm disk arrays disk failure recoverability generic failure decoding algorithm graph theory hard discs hard disk drives redundancy system recovery

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