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An accurate and highly-efficient performance evaluation approach based on queuing model for on-chip network

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Science China(Information Sciences) 2013年第7期56卷 239-258页

作者： lai mingche GAO Lei XIAO Nong WANG ZhiYing Department of Computer National University of Defense Technology

An accurate and highly-efficient analysis approach is crucial for a designer to evaluate the performance of on-chip networks. To this end, the novel M/G/1/N queuing models that capture various blocking phenomenon of the wormhole switching router are presented to compute the average waiting time accurately. With the M/G/1/N queuing models, this paper then presents the performance analysis algorithm to estimate some key metrics in terms of packet latency, buffer utilization, etc. The comparisons with SystemC simulated results show that the proposed approach with mean errors of 6.9% and 7.8% achieves the speedups of 117 and 101 for single-channel and multi-channel routers respectively. In our design methodology, this approach can direct NoC synthesis process effectively and then can be applied to multi-objective optimizations conveniently to find the best mappings.

关键词： on-chip network model performance analysis

A TLP approach for BGP based on local speculation

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Science in China(Series F) 2008年第11期51卷 1772-1784页

作者： GAO Lei GONG ZhengHu LIU YaPing lai mingche PENG Wei Department of Computer National University of Defense Technology Changsha 410073 China

With the explosive growth of Internet, the low efficiency of BGP has seriously influenced its usability. In this work, a TLP （thread level parallelism） approach with local speculation is proposed to improve the BGP performance. The thread partition is locally performed on each separated sub-module at route processing, and the speculation strategy is implemented to guarantee the memory consistency and sequential commit. Experiments on Intel Quad-core server show that this approach reaches an average speedup of 1.46 under single peer, multi-peers and route flapping. It is also shown that the packet throughput can be improved greatly under multiple sessions by taking advantage of TLP.

关键词： BGP multi-core local speculation parallelism

P3Stor: A parallel, durable flash-based SSD for enterprise-scale storage systems

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Science China(Information Sciences) 2011年第6期54卷 1129-1141页

作者： XIAO Nong , CHEN ZhiGuang, LIU Fang, lai mingche & AN LongFei Department of Computer Science, National University of Defense Technology, Changsha 410073, China Department of Computer Science National University of Defense Technology Changsha China

Driven by data-intensive applications, flash-based solid state drives (SSDs) have become increasingly popular in enterprise-scale storage systems. Flash memory exhibits inherent parallelism. However, existing solid state drives have not fully exploited this superiority. We propose P3Stor, a parallel solid state storage architecture that makes full use of flash memory by utilizing module- and bus-level parallelisms to increase average bandwidth and employing chip-level interleaving to hide I/O latency. To improve the bandwidth utilization of traditional interface protocols (e.g., SATA), P3Stor adopts PCI-E interface to support concurrent transactions. Based on the proposed parallel architecture, we design a lazy flash translation layer (LazyFTL) to manage the address space. The proposed LazyFTL adopts flexible super page-level mapping scheme to support multi-level parallelisms. It is able to distinguish hot data from cold data, and hot data identification enables LazyFTL to direct hot and cold data to separate physical blocks, which reduces page migrations when reclaiming blocks. As garbage collector migrates fewer valid pages, write amplification is significantly reduced, which in turn helps to extend the life span. Moreover, LazyFTL rarely triggers wear-leveling process. The lazy wear-leveling mechanism protects users’ requests from being disrupted by background operations. With the guidance of hot data identification, an intelligent write buffer is used to reduce program operations to flash chips. This is meaningful in extending P3Stor’s life span. The performance evaluation using trace-driven simulations and theoretical analysis shows that P3Stor achieves high performance and its life span is more than doubled.

关键词： flash memory SSD P3Stor FTL storage

Power Flow Analytical Solutions and Multi-dimensional Voltage Stability Boundaries Based on Multivariate Quotient-difference Method

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 1168-1178页

作者： Chengxi Liu Qiupin lai School of Electrical Engineering and Automation Wuhan UniversityWuhan 430072China Hubei Engineering and Technology Research Center for AC/DC Intelligent Distribution Network Wuhan 430072China IEEE

This paper proposes a novel Multivariate Quotient-Difference(MQD)method to obtain the approximate analytical solution for AC power flow ***,in the online environment,the power flow solutions covering different operating conditions can be directly obtained by plugging values into multiple symbolic variables,such that the power injections and consumptions of selected buses or areas can be independently *** method first derives a power flow solution through a Multivariate Power Series(MPS).Next,the MQD method is applied to transform the obtained MPS to a Multivariate Pad´e Approximants(MPA)to expand the Radius of Convergence(ROC),so that the accuracy of the derived analytical solution can be significantly *** addition,the hypersurface of the voltage stability boundary can be identified by an analytical formula obtained from the coefficients of *** direct method for power flow solutions and voltage stability boundaries is fast for many online applications,since such analytical solutions can be derived offline and evaluated online by only plugging values into the symbolic variables according to the actual operating *** proposed method is validated in detail on New England 39-bus and IEEE 118-bus systems with independent load variations in multi-regions.

关键词： Analytical power flow solution multivariate power series multivariate Padéapproximants multivariate quotient-difference multi-dimensional voltage stability boundary

Preface to the Special Issue:Additive Manufacturing—Expanding Production Horizon

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Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 1-2页

作者： lai-Chang Zhang Centre for Advanced Materials and Manufacturing School of EngineeringEdith Cowan University270 Joondalup DriveJoondalupPerthWA6027Australia

Additive manufacturing(AM),commonly known as 3D printing,has become a transformative technology that has a profound impact on various industrial *** encompasses a set of techniques for building objects layer by layer from digital *** conventional subtractive manufacturing methods that involve removing material from large blocks,AM adds material incrementally,providing unprecedented design flexibility and efficiency.

关键词： removing printing Expanding

Remote sensing image encryption algorithm utilizing 2D Logistic memristive hyperchaotic map and SHA-512

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Science China(Technological Sciences) 2024年第5期67卷 1553-1566页

作者： lai Qiang LIU Yuan YANG Liang School of Electrical and Automation Engineering East China Jiaotong UniversityNanchang330013China

The two-dimensional Logistic memristive hyperchaotic map(2D-LMHM)and the secure hash SHA-512 are the foundations of the unique remote sensing image encryption algorithm(RS-IEA)suggested in this *** proposed map is formed from the improved Logistic map and the memristor,which has wide phase space and hyperchaotic range and is exceptionally excellent to be utilized in specific *** proposed image algorithm uses the permutation-assignment-diffusion *** generates two position matrices in a progressive manner to achieve an efficient random exchange of pixel positions,assignment is carried through on the image pixels of the permutated image to entirely remove the original image information,strengthening the relationship between permutation and diffusion,and loop diffusion in two different directions can use subtle changes of pixels to affect the whole *** random key and plain-image SHA-512 hash values are used to produce an additional key,which is then utilized to figure out the permutation parameters and the initial value of a chaotic *** experimental results with the average NPCR=99.6094%(NPCR:number of pixels change rate),average UACI=33.4638%(UACI:unified average changing intensity),100%pass rate of the targets in the test set,the average correlation coefficient is 0.00075,and the local information entropy is 7.9025,which shows that the algorithm is able to defend against a variety of illegal attacks and provide more trustworthy protection than some of the existing state-of-the-art algorithms.

关键词： chaos memristive hyperchaotic map remote sensing SHA-512 image encryption RS-IEA

Supercoiled DNA Minicircles under Double-strand Breaks

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Chinese Journal of Polymer Science 2024年第9期42卷 1353-1359,I0007页

作者： Ye-Peng Qiao Chun-lai Ren National Laboratory of Solid State Microstructures and Department of Physics Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing210093China

Understanding how supercoiled DNA releases intramolecular stress is essential for its functional ***,the molecular mechanism underlying the relaxation process remains insufficiently *** we employed MD simulations based on the oxDNA2 model to investigate the relaxation process of a 336-base pair supercoiled minicircular DNA under double-strand breaks with two fixed *** simulations show that the conformational changes in the DNA occur continuously,with intramolecular stress release happening abruptly only when the DNA chain traverses the breakage *** relaxation process is influenced not only by the separation distance between the fixed ends but also their ***,we observe an inhibitory effect on the relaxation characterized by small angles,where short terminal loops impede DNA conformational adjustments,preserving the supercoiled *** findings elucidate the intricate interplay between DNA conformational change,DNA motion and intramolecular stress release,shedding light on the mechanisms governing the relaxation of supercoiled DNA at the molecular level.

关键词： Supercoiled DNA DNA minicircle DNA relaxation oxDNA model MD simulation

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高性能计算技术及标准现状分析

计算机科学 2023年第11期50卷 1-7页

作者：陆平静熊泽宇赖明澈国防科技大学计算机学院长沙410073

高性能计算是科技创新体系的重要组成,是知识创新和技术创新的重要能力支撑,是新时期下与理论、实验并重的三大科技创新手段之一。在过去的三十年间,高性能计算取得了以突飞猛进的进展,高性能计算已经进入E级计算时代,我国在高性能计算... 详细信息

高性能计算是科技创新体系的重要组成,是知识创新和技术创新的重要能力支撑,是新时期下与理论、实验并重的三大科技创新手段之一。在过去的三十年间,高性能计算取得了以突飞猛进的进展,高性能计算已经进入E级计算时代,我国在高性能计算领域也取得了跨越式的发展,取得了天河、神威、曙光为代表的一系列成果,高性能系统研制水平跻身国际一流行列。随着摩尔定律接近极限,高性能计算技术的性能提升之路面临巨大挑战,在后摩尔时代,将依赖算法、软件和硬件架构去提升高性能计算机系统的终极性能。另一方面,与高性能计算机技术飞速发展相比,高性能计算标准的发展还存在很多不足。文中首先分析了当前国内外高性能计算机技术的发展现状及趋势,然后剖析了当前国内外高性能计算标准的现状及趋势,最后给出了当前发展中国高性能计算机标准的必要性和重要性。

关键词：高性能计算 E级计算计算机体系结构标准集群大规模并行处理机后摩尔时代

First Digit Distributions of Gamma-Ray Bursts

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Research in Astronomy and Astrophysics 2024年第5期24卷 70-75页

作者： Hou-Yu lai Jun-Jie Wei Purple Mountain Observatory Chinese Academy of SciencesNanjing 210023China School of Astronomy and Space Sciences University of Science and Technology of ChinaHefei 230026China

The occurrence of the first significant digits from real world sources is usually not equally distributed,but is consistent with a logarithmic distribution instead,known as Benford’s *** this work,we perform a comprehensive investigation on the first digit distributions of the duration,fluence,and energy flux of gamma-ray bursts (GRBs) for the first *** a complete GRB sample detected by the Fermi satellite,we find that the first digits of the duration and fluence adhere to Benford’s ***,the energy flux shows a significant departure from this law,which may be due to the fact that a considerable part of the energy flux measurements is restricted by lack of spectral *** on the conventional duration classification scheme,we also check if the durations and fluences of long and short GRBs (with duration T_(90)>2 s and T_(90)≤2 s,respectively) obey Benford’s *** find that the fluences of both long and short GRBs still agree with the Benford distribution,but their durations do not follow Benford’s *** results hint that the long–short GRB classification scheme does not directly represent the intrinsic physical classification scheme.

关键词： (stars:)gamma-ray burst general-methods statistical-astronomical databases miscellaneous