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Curvature of Pseudocritical Transition Line for Two-Flavor QCD with Improved Kogut-Susskind Quarks

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Chinese Physics Letters 2017年第4期34卷 18-21页

作者： Liang-Kai Wu Xiang-Fei Meng Fa-Ling Zhang Faculty of Science Jiangsu University Zhenjiang 212013 National supercomputer center Tianjin 300457

The results on the curvature of a pseudocritical transition line for two-flavor QCD through lattice simulations are presented. The simulations are carried out with Symanzik-improved gauge action and Asqtad fermion action on a lattice 12^3×4 at quark mass am = 0.010. At the imaginary chemical potentials aμ1 = 0.050, 0.150, 0.200, 0.225 and 0.250, we investigate the chiral condensate ψψ, plaquette variable P and imaginary part of Polyakov loop Im（L） and their susceptibilities. Analytic continuation from an imaginary chemical potential to a real one is used to obtain the expression for transition temperature as a function of the chemical potential. The curvature is 0.0326（46）.

关键词： QCD Curvature of Pseudocritical Transition Line for Two-Flavor QCD with Improved Kogut-Susskind Quarks

Initiative Optimization Operation Strategy and Multi-objective Energy Management Method for Combined Cooling Heating and Power

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IEEE/CAA Journal of Automatica Sinica 2016年第4期3卷 385-393页

作者： Feng Zhao Chenghui Zhang Bo Sun School of Control Science and Engineering Shandong University Shandong Computer Science center (National supercomputer center in Jinan)

This paper proposed an initiative optimization operation strategy and multi-objective energy management method for combined cooling heating and power U+0028 CCHP U+0029 with storage systems. Initially, the initiative optimization operation strategy of CCHP system in the cooling season, the heating season and the transition season was formulated. The energy management of CCHP system was optimized by the multi-objective optimization model with maximum daily energy efficiency, minimum daily carbon emissions and minimum daily operation cost based on the proposed initiative optimization operation strategy. Furthermore, the pareto optimal solution set was solved by using the niche particle swarm multi-objective optimization algorithm. Ultimately, the most satisfactory energy management scheme was obtained by using the technique for order preference by similarity to ideal solution U+0028 TOPSIS U+0029 method. A case study of CCHP system used in a hospital in the north of China validated the effectiveness of this method. The results showed that the satisfactory energy management scheme of CCHP system was obtained based on this initiative optimization operation strategy and multi-objective energy management method. The CCHP system has achieved better energy efficiency, environmental protection and economic benefits. © 2014 Chinese Association of Automation.

关键词： Carbon Cooling Cooling systems Energy efficiency Energy management Heating Multiobjective optimization Optimization Pareto principle

A HYBRID GRANULARITY PARALLEL ALGORITHM FOR PRECISE INTEGRATION OF STRUCTURAL DYNAMIC RESPONSES

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Acta Mechanica Solida Sinica 2008年第1期21卷 28-33页

作者： Yuanyin Li Xianlong Jin Genguo Li High Performance Computing center Shanghai Jiaotong University Shanghai 200240 China Shanghai supercomputer center Shanghai 201203 China

Precise integration methods to solve structural dynamic responses and the corresponding time integration formula are composed of two parts： the multiplication of an exponential matrix with a vector and the integration term. The second term can be solved by the series solution. Two hybrid granularity parallel algorithms are designed, that is, the exponential matrix and the first term are computed by the fine-grained parallel algorithra and the second term is computed by the coarse-grained parallel algorithm. Numerical examples show that these two hybrid granularity parallel algorithms obtain higher speedup and parallel efficiency than two existing parallel algorithms.

关键词： dynamic response precise integration hybrid granularity parallel algorithm

Strain-tunable electronic and transport properties of MoS2 nanotubes

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Nano Research 2014年第4期7卷 518-527页

作者： Weifeng Li Gang Zhang Meng Guo Yong-Wei Zhang Institute of High Performance Computing A＊STAR Singapore 138632 Singapore National supercomputer center in Jinan Shandong Computer Science Center China

Using density functional theory calculations, we have investigated the mechanical properties and strain effects on the electronic structure and transport properties of molybdenum disulfide （MoS2） nanotubes. At a similar diameter, an armchair nanotube has a higher Young＇s modulus and Poisson ratio than its zigzag counterpart due to the different orientations of Mo-S bond topologies. An increase in axial tensile strain leads to a progressive decrease in the band gap for both armchair and zigzag nanotubes. For armchair nanotube, however, there is a semiconductor-to-metal transition at the tensile strain of about 8%. For both armchair and zigzag nanotubes, the effective mass of a hole is uniformly larger than its electron counterpart, and is more sensitive to strain. Based on deformation potential theory, we have calculated the carrier mobilities of MoS2 nanotubes. It is found that the hole mobility is higher than its electron counterpart for armchair （6, 6） nanotube while the electron mobility is higher than its hole counterpart for zigzag （10, 0） nanotube. Our results highlight the tunable electronic properties of MoS2 nanotubes, promising for interesting applications in nanodevices, such as opto-electronics, photoluminescence, electronic switch and nanoscale strain sensor.

关键词： MoS2 nanotube strain engineering semiconductor-to-metaltransition carrier mobility density functional theory

Storage wall for exascale supercomputing

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Frontiers of Information Technology & Electronic Engineering 2016年第11期17卷 1154-1175页

作者： Wei HU Guang-ming LIU Qiong LI Yan-huang JIANG Gui-lin CAI College of Computer National University of Defense TechnologyChangsha 410073China National supercomputer center in Tianjin Tianjin 300457China

The mismatch between compute performance and I/O performance has long been a stumbling block as supercomputers evolve from petaflops to exaflops. Currently, many parallel applications are I/O intensive,and their overall running times are typically limited by I/O performance. To quantify the I/O performance bottleneck and highlight the significance of achieving scalable performance in peta/exascale supercomputing, in this paper, we introduce for the first time a formal definition of the ‘storage wall' from the perspective of parallel application scalability. We quantify the effects of the storage bottleneck by providing a storage-bounded speedup,defining the storage wall quantitatively, presenting existence theorems for the storage wall, and classifying the system architectures depending on I/O performance variation. We analyze and extrapolate the existence of the storage wall by experiments on Tianhe-1A and case studies on Jaguar. These results provide insights on how to alleviate the storage wall bottleneck in system design and achieve hardware/software optimizations in peta/exascale supercomputing.

关键词： Storage-bounded speedup Storage wall High performance computing Exascale computing

AquaSee: Predict Load and Cooling System Faults of supercomputers Using Chilled Water Data

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Journal of Computer Science & Technology 2020年第1期35卷 221-230页

作者： Yu-Qi Li Li-Quan Xiao Jing-Hua Feng Bin Xu Jian Zhang National supercomputer center in Tianjin Tianjin 300450China College of Computer National University of Defense TechnologyChangsha 410073China

An analysis of real-world operational data of Tianhe-1A(TH-1A)supercomputer system shows that chilled water data not only can reflect the status of a chiller system but also are related to supercomputer *** study proposes AquaSee,a method that can predict the load and cooling system faults of supercomputers by using chilled water pressure and temperature *** method is validated on the basis of real-world operational data of the TH-1A supercomputer system at the National supercomputer center in *** with various compositions are used to construct the prediction model,which is also established using different prediction sequence *** results show that the method that uses a combination of pressure and temperature data performs more effectively than that only consisting of either pressure or temperature *** best inference sequence length is two ***,an anomaly monitoring system is set up by using chilled water data to help engineers detect chiller system anomalies.

关键词： supercomputer chilled water data sensor network load prediction

Determination of the vapor–liquid transition of square-well particles using a novel generalized-canonical-ensemble-based method

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Chinese Physics B 2017年第6期26卷 8-13页

作者：赵亮徐顺涂育松周昕 College of Physical Science and Technology Yangzhou University supercomputer center Computer Network Information CenterChinese Academy of Sciences School of Physical Sciences University of Chinese Academy of Sciences

The square-well（SW） potential is one of the simplest pair potential models and its phase behavior has been clearly revealed, therefore it has become a benchmark for checking new theories or numerical methods. We introduce the generalized canonical ensemble（GCE） into the isobaric replica exchange Monte Carlo（REMC） algorithm to form a novel isobaric GCE-REMC method, and apply it to the study of vapor–liquid transition of SW particles. It is validated that this method can reproduce the vapor–liquid diagram of SW particles by comparing the estimated vapor–liquid binodals and the critical point with those from the literature. The notable advantage of this method is that the unstable vapor–liquid coexisting states,which cannot be detected using conventional sampling techniques, are accessed with a high sampling efficiency. Besides,the isobaric GCE-REMC method can visit all the possible states, including stable, metastable or unstable states during the phase transition over a wide pressure range, providing an effective pathway to understand complex phase transitions during the nucleation or crystallization process in physical or biological systems.

关键词： square-well particles phase-coexisting states generalized canonical ensemble replica exchange Monte Carlo

An Approach to Analyze Physical Memory Image File of Mac OS X

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Journal of Harbin Institute of Technology(New Series) 2014年第4期21卷 116-120页

作者： Li-Juan Xu Lian-Hai Wang Shandong Provincial Key Laboratory of Computer Network Shandong Computer Science Center( National Supercomputer Center in Jinan)

Memory analysis is one of the key techniques in computer live forensics. Especially,the analysis of a Mac OS X operating system's memory image file plays an important role in identifying the running status of an apple computer. However,how to analyze the image file without using extra"mach-kernel"file is one of the unsolved difficulties. In this paper,we firstly compare several approaches for physical memory acquisition and analyze the effects of each approach on physical memory. Then,we discuss the traditional methods for the physical memory file analysis of Mac OS X. A novel physical memory image file analysis approach without using extra"mach-kernel"file is proposed base on the discussion. We verify the performance of the new approach on Mac OS X 10. 8. 2. The experimental results show that the proposed approach is simpler and more practical than previous ones.

关键词： computer forensics live forensics Mac OS X operating system physical memory analysis

Design and Implementation of the Tianhe-2 Data Storage and Management System

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Journal of Computer Science & Technology 2020年第1期35卷 27-46页

作者： Yu-Tong Lu Peng Cheng Zhi-Guang Chen National supercomputer center in Guangzhou Sun Yat-sen UniversityGuangzhou 510000China College of Computer National University of Defense TechnologyChangsha 410073China

With the convergence of high-performance computing(HPC),big data and artificial intelligence(AI),the HPC community is pushing for"triple use"systems to expedite scientific ***,supporting these converged applications on HPC systems presents formidable challenges in terms of storage and data management due to the explosive growth of scientific data and the fundamental differences in I/O characteristics among HPC,big data and AI *** this paper,we discuss the driving force behind the converging trend,highlight three data management challenges,and summarize our efforts in addressing these data management challenges on a typical HPC system at the parallel file system,data management middleware,and user application *** HPC systems are approaching the border of exascale computing,this paper sheds light on how to enable application-driven data management as a preliminary step toward the deep convergence of exascale computing ecosystems,big data,and AI.

关键词： high-performance computing(HPC) data management converged application parallel file system