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Computer comparisons in the presence of performance variation

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Frontiers of Computer Science 2020年第1期14卷 21-41页

作者： Samuel IRVING Bin LI Shaoming CHEN Lu peng Weihua ZHANG Lide DUAN Louisiana State University Baton RougeLA 70803USA Shanghai Institute of Intelligent Electronics&Systems Shanghai 201203China Software School Fudan UniversityShanghai 201203China Shanghai Key Laboratory of Data Science Fudan UniversityShanghai 200433China University of Texas at San Antonio San AntonioTX 78249USA

Performance variability,stemming from nondeterministic hardware and software behaviors or deterministic behaviors such as measurement bias,is a well-known phenomenon of computer systems which increases the difficulty of comparing computer performance metrics and is slated to become even more of a concern as interest in Big Data analytic *** methods use various measures(such as geometric mean)to quantify the performance of different benchmarks to compare computers without considering this variability which may lead to wrong *** this paper,we propose three resampling methods for performance evaluation and comparison:a randomization test for a general performance comparison between two computers,bootstrapping confidence estimation,and an empirical distribution and five-number-summary for performance *** results show that for both PARSEC and highvariance BigDataBench benchmarks 1)the randomization test substantially improves our chance to identify the difference between performance comparisons when the difference is not large;2)bootstrapping confidence estimation provides an accurate confidence interval for the performance comparison measure(e.g.,ratio of geometric means);and 3)when the difference is very small,a single test is often not enough to reveal the nature of the computer performance due to the variability of computer *** further propose using empirical distribution to evaluate computer performance and a five-number-summary to summarize computer *** use published SPEC 2006 results to investigate the sources of performance variation by predicting performance and relative variation for 8,236 *** achieve a correlation of predicted performances of 0.992 and a correlation of predicted and measured relative variation of ***,we propose the utilization of a novel biplotting technique to visualize the effectiveness of benchmarks and cluster machines by *** illustrate the results and concl

关键词： performance of systems variation performance attributes measurement evaluation modeling simulation of multiple-processor systems experimental design Big Data

Climate variability and predictability associated with the Indo-Pacific Oceanic Channel Dynamics in the CCSM4 Coupled System Model

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Chinese Journal of Oceanology and Limnology 2017年第1期35卷 23-38页

作者： YUAN Dongliang XU peng XU Tengfei Key Laboratory of Ocean Circulation and Waves （KLOCAW） Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China Qingdao Collaborative Innovation Center of Marine Science and Technology Qingdao 266003 China University of Chinese Academy of Sciences Beoing 100049 China First Institute of Oceanography State Oceanic Administration Qingdao 266061 China

An experiment using the Community Climate System Model(CCSM4), a participant of the Coupled Model Intercomparison Project phase-5(CMIP5), is analyzed to assess the skills of this model in simulating and predicting the climate variabilities associated with the oceanic channel dynamics across the Indo-Pacific Oceans. The results of these analyses suggest that the model is able to reproduce the observed lag correlation between the oceanic anomalies in the southeastern tropical Indian Ocean and those in the cold tongue in the eastern equatorial Pacific Ocean at a time lag of 1 year. This success may be largely attributed to the successful simulation of the interannual variations of the Indonesian Throughflow, which carries the anomalies of the Indian Ocean Dipole(IOD) into the western equatorial Pacific Ocean to produce subsurface temperature anomalies, which in turn propagate to the eastern equatorial Pacific to generate ENSO. This connection is termed the "oceanic channel dynamics" and is shown to be consistent with the observational analyses. However, the model simulates a weaker connection between the IOD and the interannual variability of the Indonesian Throughflow transport than found in the observations. In addition, the model overestimates the westerly wind anomalies in the western-central equatorial Pacific in the year following the IOD, which forces unrealistic upwelling Rossby waves in the western equatorial Pacific and downwelling Kelvin waves in the east. This assessment suggests that the CCSM4 coupled climate system has underestimated the oceanic channel dynamics and overestimated the atmospheric bridge processes.

关键词： Indian Ocean Dipole El Nino-Southern Oscillations(ENSO) oceanic channel Community Climate System Model(CCSM4) Indonesian Throughflow ENSO predictability

Decohesion of graphene from a uniaxially-stretched substrate:Failure analysis of a frictional adhesive interface

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Friction 2024年第3期12卷 510-521页

作者： Bo peng Chaochen XU Qingao WANG Pei ZHAO Xiqiao FENG Qunyang LI AML Department of Engineering MechanicsTsinghua UniversityBeijing 100084China State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China Center for X-Mechanics and Institute of Applied Mechanics Zhejiang UniversityHangzhou 310027China State Key Laboratory of Fluid Power and M

Composite structures consisting of two-dimensional(2D)materials deposited on elastic substrates have a wide range of potential applications in flexible *** such devices,robust 2D film/substrate interfacial adhesion is essential for their reliable performance when subjected to external thermal and mechanical *** better understand the strength and failure behavior of the 2D film/substrate interfaces,two types of graphene/polymer samples with distinct interfacial adhesion properties are fabricated and tested by uniaxially stretching the *** on the interfacial adhesion,two drastically different debonding rates are observed,i.e.,rapid snap-through debonding and more progressive crack *** by the experimental observation,we propose an improved shear-lag model with a trapezoidal-shaped cohesive zone to derive an analytical solution for the decohesion *** theoretical model reveals that the decohesion behavior of the frictional adhesive interface is governed by three dimensionless ***,the dimensionless length of the film essentially determines the decohesion rate;while the other two parameters affect the critical substrate strain to initiate *** fitting the experimental data with the theoretical model,the intrinsic adhesion properties of the two samples are obtained with physically meaningful *** work offers an analytical solution to describing the decohesion behavior of general thin film/substrate systems with a frictional adhesive interface,which is beneficial for characterizing and optimizing the mechanical properties of various thin film/polymer devices.

关键词： film/substrate systems adhesion frictional sliding interface decohesion cohesive-zone model

Study on the Size Distribution and Similarity Law of Bubble Nuclei in Water

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China Ocean Engineering 2021年第3期35卷 432-442页

作者： YAO Xiong-liang LI Zhi-peng SUN Long-quan CHEN Wei-chu College of Shipbuilding Engineering Harbin Engineering UniversityHarbin 150001China

To study the distribution characteristics and similarity laws of nuclei under different pressures,based on the selfdesigned decompression chamber and the acoustic measuring system,the size distributions of nuclei in the degassed tap water under negative ambient pressures were measured.A number density distribution function of nuclei based on the modified Weibull distribution function was proposed and verified by the experimental measurement results and some published data of nuclei size *** on this nuclei number density distribution function,the similarity law of the nuclei size distribution was analyzed:in the scale experiment,the value of exponential in the similarity law of the nuclei number density should be determined by the nuclei size distribution of the water in the prototype experiment and the actual nuclei size distribution of the water in the model *** a precondition is that the nuclei size distributions are similar.

关键词： nuclei number density distribution function microbubble ambient pressure similarity law

Preparation of nitrogen and sulfur co-doped ultrathin graphitic carbon via annealing bagasse lignin as potential electrocatalyst towards oxygen reduction reaction in alkaline and acid media

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Journal of Energy Chemistry 2019年第7期28卷 33-42页

作者： Yixing Shen Feng peng Yonghai Cao Jianliang Zuo Hongjuan Wang Hao Yu School of Chemistry and Chemical Engineering South China University of TechnologyGuangzhou 510640GuangdongChina Guangzhou Key Laboratory for New Energy and Green Catalysis School of Chemistry and Chemical EngineeringGuangzhou UniversityGuangzhou 510006GuangdongChina

Renewable lignin used for synthesizing materials has been proven to be highly potential in specific ***,we report a simple method to synthesize nitrogen and sulfur co-doped carbon nanosheets by using bagasse lignin,denoted as lignin-derived carbon(LC).By adjusting the ratio of nitrogen source and annealing temperature,we obtained the ultrathin graphitic lignin carbon(LC-4-1000)with abundant wrinkles with high surface area of 1208 m2g_1 and large pore volume of 1.40 cm3g_*** alkaline medium,LC-4-1000 has more positive half-wave potential and nearly current density compared to commercial Pt/C for oxygen reduction reaction(ORR).More importantly,LC-4-1000 also exhibits comparable activity and superior stability for ORR in acid medium due to its high graphitic N ratio and a direct four electron pathway for *** study develops a cost-effective and highly efficient method to prepare biocarbon catalyst for ORR in fuel cells.

关键词： Electrocatalyst Biocarbon Lignin Nitrogen and sulfur co-doped carbon Oxygen reduction reaction

A review on carrier aircraft dispatch path planning and control on deck

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Chinese Journal of Aeronautics 2020年第12期33卷 3039-3057页

作者： Xinwei WANG Jie LIU Xichao SU Haijun peng Xudong ZHAO Chen LU Department of Engineering Mechanics State Key Laboratory of Structural Analysis for Industrial EquipmentDalian University of TechnologyDalian 116024China Faculty of Electronic Information and Electrical Engineering Dalian University of TechnologyDalian 116024China War Research Institute Academy of Military SciencesBeijing 100850China Department of Airborne Vehicle Engineering Naval Aeronautical and Astronautical UniversityYantai 264001China School of Reliability and Systems Engineering Beihang UniversityBeijing 100083China

As an important part in sortie/recovery process,the dispatch of carrier aircraft not only affects the sortie/recovery efficiency and safety,but also has severe influence on the carrier's combat efficiency and the comprehensive support *** planning is the key to improve the efficiency and safety during the dispatch *** main purpose of this paper is to propose a comprehensive investigation of techniques and research progress for the carrier aircraft's dispatch path planning on the *** different dispatch modes of carrier aircraft and the corresponding modeling technologies are investigated,and the aircraft's dispatch path planning techniques and algorithms have been classified into different ***,their assumptions and drawbacks have been discussed for single aircraft and multiple *** make the research work more comprehensive,the corresponding tracking control methodologies are also ***,due to the similarity of path planning problem between the carrier aircraft's dispatch and those in other fields,this paper provides an exploratory prospect of the knowledge or method learned from other fields.

关键词： Carrier aircraft Dispatch Kinematic model Path planning Path tracking

A large-scale experimental study on CO_(2) capture utilizing slurry-based ab-adsorption approach

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Chinese Journal of Chemical Engineering 2021年第3期34卷 56-66页

作者： Shuren Yan peng Xiao Ding Zhu Hai Li Guangjin Chen Bei Liu State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing 102249China

The increasing concentration of CO_(2) in atmosphere is deemed the main reason of global ***,efficiently capturing CO_(2) from various sources with energy conservation is of great ***,a series of experiments were carried out to successfully test the slurry-based ab-adsorption method for continuously capturing CO_(2) in the large-scale cycled separation unit with cost-effect taking into account the scale-up criteria.A bubble column(with height 4900 mm and inner diameter 376 mm)and a desorption tank(with volume 310 L)are the essential components of the separation *** novel slurry used in this study was formed with zeolitic imidazolate framework-8 and 2-methylimidazole-water *** influence of operation conditions was investigated *** results show that increasing sorption pressure and slurry height level,decreasing gas volume flow and sorption temperature are beneficial for separation *** volume fraction of CO_(2) in the feed gas was also *** the scale-up effect had been observed and it was found that it exerted a negative effect on CO_(2) capture,depending on experimental conditions,CO_(2) removal efficiency could still reach 85%-95%and the maximum CO_(2) loading in the recycled slurry could be up to0.007 mol·L-1·***,the slurry-based method could be operated well even under very moderate regeneration conditions(333 K and 0.05 MPa),which means that the novel approach shows greater energy conservation than traditional amine absorption methods.

关键词： CO_(2)capture Zeolitic imidazolate framework-8 Slurry Bubble column Scale-up

Feasibility study of thermo-compensated resistance brazing welding of C/C composites and T2 copper with AgCuTi filler metal

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Chinese Journal of Aeronautics 2023年第5期36卷 534-548页

作者： Jiang YU Xinglin MIAO Hongtao ZHANG Bo WANG Changming QU peng HE State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China Institute for Shipwelding Technology Shandong Institute of Shipbuilding TechnologyWeihai 264209China

The dissimilar materials joining of C/C composites to T2 copper were performed successfully by thermo-compensated Resistance Brazing Welding(RBW)with AgCuTi filler *** interfacial microstructure,phase composition,and shear strength of the resistance brazed joints were investigated by the relevant analysis *** results indicated that the order affecting the shear strength of the C/C-Cu joint was welding current,welding pressure,and welding time in *** shear strength of backward thermo-compensated RBW was higher than that of forward thermo-compensated RBW due to the Peltier *** maximum shear strength of the C/C-Cu joint was 11.56 MPa in the optimized welding parameter with welding current of 8.0 kA,welding time of 60 ms,and welding pressure of 0.10 MPa by backward thermo-compensated *** interface structure at the resistance brazed joint with this welding parameter was C/C composites/TiC/Cu(s.s)/T2 *** TiC phase was verified at the interface of the brazed joint by Scanning Electron Microscope(SEM),Energy-Dispersive X-ray Spectrometer(EDS),and X-ray Diffraction(XRD).Considerable fractures occurred in the C/C composites and partial fracture occurred at the interfacial reaction layer.

关键词： AgCuTi C/C composites Copper Resistance Brazing welding Shear strength

Promoting the La solution in 2:14:1-type compound:Resultant chemical deviation and microstructural nanoheterogeneity

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Journal of Materials Science & Technology 2021年第3期62卷 195-202页

作者： Yongsheng Liu Jiaying Jin Tianyu Ma Baixing peng Xinhua Wang Mi Yan School of Materials Science and Engineering State Key Laboratory of Silicon materialsKey Laboratory of Novel Materials for Information Technology of Zhejiang ProvinceZhejiang UniversityHangzhou310027China

RE_(2)Fe_(14)B-based(RE,rare earth)permanent magnets containing abundant and cheap La/Ce have attracted intense attention *** comparison with Ce that can fully replace Nd in the 2:14:1 lattice,La substitution for Nd has long been limited at a low *** we present that through doping La35 Ce65 alloy with the La/Ce ratio in natural mineral,stable 2:14:1 phase can be maintained at 1273 K within the entire substitution range of[(La_(35)Ce_(65))、(Pr_(20)Nd_(80))_(1-x)]_(2.14)Fe_(14)B(0.6≤x≤1.0,at.%),as verified by composition analysis,microstructural characterization and magnetic ***,the promoted La solution in 2:14:1 phase induces two unique findings upon coexisting La-Ce-Pr-Nd:i)Compared to Ce that fits well with the nominal concentration,La deviates noticeably from the nominal one;ii)Nanoscale spinodal-decomposition-like phase separation is observed due to different solubilities of La-Ce-Pr-Nd elements in 2:14:1 *** joint effects induce higher Curie temperature than estimation based on the rule of mixture,which delights the prospect of La_(35)Ce_(65)alloy in developing low-cost permanent materials.

关键词： La-Ce Permanent magnets Nd-Fe-B Microstructure