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Microstructural evolution and mechanical properties of Ni-45Ti-5Al-2Nb-1Mo alloy subjected to different heat treatments

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Rare Metals 2023年第8期42卷 2774-2780页

作者： xiao-Yun Song Yan Li fei Zhang State Key Laboratory of Nonferrous Metals and Processes GRIMAT Engineering Institute Co.LtdBeijing 101407China School of Materials Science and Engineering Beihang UniversityBeijing 100191China

The effects of solution and aging heat treatment on microstructural evolution and room temperature tensile properties for as-forged Ni-45Ti-5Al-2Nb-1Mo alloy were investigated through scanning electron microscopy(SEM),transmission electron microscopy(TEM)and tensile *** results show that the microstructure of solution-treated alloy comprises NiTi matrix,Ti_(2)Ni and(Nb,Ti)ss *** aging treatment at 700℃for 6 and100 h,the distribution of Ti_(2)Ni and(Nb,Ti)ss precipitates increases in *** new type of precipitate is observed in the specimen aged at 700℃.After aging at800℃for 100 h,numerous nanosized Ni_(2)TiAl phases are precipitated within the *** and aging treatments improve the tensile properties at room *** strength and ductility are improved after solution treatment at 1100℃plus aging treatment at 800℃for 6 h or 700℃for 100 *** aging time prolonging to 100 h at 800℃,the precipitation of fine Ni2TiAl particles leads to the improvement in tensile strength and deterioration of elongation.

关键词： NiTi-Al-based alloy Intermetallics Microstructure Mechanical properties Heat treatment

Revisiting Persistent Indexing Structures on Intel Optane DCPersistent Memory

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Journal of Computer Science & Technology 2021年第1期36卷 140-157页

作者： Heng Bu Ming-Kai Dong Ji-fei Yi Bin-Yu zang Hai-Bo Chen Institute of Parallel and Distributed Systems Shanghai Jiao Tong UniversityShanghai 200240China

Persistent indexing structures are proposed in response to emerging non-volatile memory(NVM)to provide high performance yet durable ***,due to the lack of real NVM hardware,many prior persistent indexing structures were evaluated via emulation,which varies a lot across different setups and differs from the real ***,Intel has released its Optane DC Persistent Memory Module(PMM),which is the first production-ready *** this paper,we revisit popular persistent indexing structures on PMM and conduct comprehensive evaluations to study the performance differences among persistent indexing structures,including persistent hash tables and persistent *** to the evaluation results,we find that Cacheline-Conscious Extendible Hashing(CCEH)achieves the best performance among all evaluated persistent hash tables,and Failure-Atomic ShifT B+-Tree(FAST)and Write Optimal Radix Tree(WORT)perform better than other ***,we find that the insertion performance of hash tables is heavily influenced by data locality,while the insertion latency of trees is dominated by the flush *** also uncover that no existing emulation methods accurately simulate PMM for all the studied data ***,we provide three suggestions on how to fully utilize PMM for better performance,including using clflushopt/clwb with sfence instead of clflush,flushing continuous data in a batch,and avoiding data access immediately after it is flushed to PMM.

关键词： persistent memory data structure performance Intel Optane DC persistent memory module(PMM)

Cytological and molecular characteristics of delayed spike development in wheat under low temperature in early spring

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The Crop Journal 2022年第3期10卷 840-852页

作者： Xurun Yu Yufei Jiang Huihui Yao Liping Ran Yong zang fei Xiong Jiangsu Key Laboratory of Crop Genetics and Physiology/Jiangsu Key Laboratory of Crop Cultivation and Physiology Agricultural College of Yangzhou UniversityCo-Innovation Center for Modern Production Technology of Grain CropsYangzhou UniversityYangzhou 225009JiangsuChina Yangzhou University Guangling College Yangzhou 225000JiangsuChina

Low temperature in early spring impairs wheat growth and grain ***,little is known about the cytological and molecular mechanisms underlying low temperature regulation of wheat spike *** observation and transcriptome sequencing of wheat spikes under low temperature were *** temperature slowed spike development,reduced the yield-component parameters of wheat spikes at the harvest stage,delayed the formation of lateral spikelets and tissue development,and induced the early differentiation of terminal *** temperature increased the content of abscisic acid and caused the upregulation of genes in the abscisic acid signaling pathway,including those encoding PP2 Cs,Sn RK2 s,and b ZIP transcription *** temperature also induced the upregulation of 33 cold-responsive genes involved in wheat response to low-temperature stress and regulation of abscisic acid biosynthesis and metabolism of other *** wheat spike adapted to cold conditions by changing the expression levels of genes involved in spike morphogenesis,including the transcription-factor genes MADS6,ERF4,ERF78,WOX6,and *** findings suggest that low temperature in early spring delays wheat spike development by increasing abscisic acid content or affecting the expression of genes involved in morphogenesis.

关键词： Development Low temperature Spike Transcriptome Wheat

Conductivity of carbon-based molecular junctions from ab-initio methods

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Frontiers of physics 2014年第6期9卷 748-759页

作者： xiao-fei Li Yi Luo School of Optoelectronic Information University of Electronic Science and Technology of China Chengdu 610054 China Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of China Hefei 230026 China KTH Royal Institute of Technology School of Biotechnology Division of Theoretical Chemistry and Biology S-106 91 Stockholm Sweden

Carbon nanomaterials （CNMs） are prompting candidates tor next generational electronics. In this review we provide a mini overview of recent results on the conductivity of carbon-based molecular junctions obtained from ab-mitio methods. CNMs used as nanoelectrodes and molecular materials in molecular junctions are discussed. The flmctionalities that include the nanomechanically controlled molecular conductance switches, negative differential resistance devices, and electronic rectifiers realized by using CNMs have been demonstrated.

关键词： carbon nanotubes graphene all-carbon nanodevice quantum transport ab-initio molecular dynamics simulations

Studies on Electrochemical Property of LiFePO_4/C as Cathode Material for Lithium Ion Batteries

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Chemical Research in Chinese Universities 2006年第1期22卷 73-75页

作者： HUANG xiao-wen SHI Peng-fei Faculty of Applied Chemistry Harbin Institute of Technology Harbin 150001 P.R. China College of Material Science and Engineering Shandong University of Science and Technology Qingdao 266510 P. R. China

LiFePO4/C samples were prepared at different temperatures by adding sngar to the synthetic precursor. The samples were characterized by X-ray diffraction（XRD）. Their crystal phases show an olivine structure. Only the sample obtained at 700℃ has a larger discharge capacity, which has good electrochemical properties： its discharge specific capacity is 120. 3 mAh/g at a current of 0. 05 mA, and its capacity fade is very low after 20 cycles. It is demonstrated that the best synthetic temperature should be 700℃.

关键词： Olivine Lithium ion battery Carbon-coated LiFePO4

Brake Orbits of First Order Convex Hamiltonian Systems with Particular Anisotropic Growth

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Acta Mathematica Sinica,English Series 2020年第2期36卷 171-178页

作者： xiao fei ZHANG Chun Gen LIU School of Mathematics and Statistics Shanxi Datong UniversityDatong 037009P.R.China School of Mathematics and Information Science Guangzhou UniversityGuangzhou 510006P.R.China

Combining the dual least action principle with Mountain-pass lemma,we obtain the existence of brake orbits for first-order convex Hamiltonian systems with particular anisotropic growth.

关键词： Hamiltonian system brake orbit anisotropic grow th Mountain-pass lemma

Ince-Strutt Stability Charts for Ship Parametric Roll Resonance in Irregular Waves

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China Ocean Engineering 2017年第4期31卷 447-457页

作者： ZHANG xiao YANG He-zhen xiao fei XU Pei-ji National Key Laboratory on Ship Vibration &Noise China Ship Development and Design Center State Key Laboratory of Ocean Engineering School of Naval Architecture.Ocean and Civil EngineeringShanghai Jiao Tong University School of Civil and Environmental Engineering Nanyang Technological University

Ince-Strutt stability chart of ship parametric roll resonance in irregular waves is conducted and utilized for the exploration of the parametric roll resonance in irregular waves. Ship parametric roll resonance will lead to large amplitude roll motion and even wreck. Firstly, the equation describing the parametric roll resonance in irregular waves is derived according to Grim’s effective theory and the corresponding Ince-Strutt stability charts are obtained. Secondly, the differences of stability charts for the parametric roll resonance in irregular and regular waves are compared. Thirdly, wave phases and peak periods are taken into consideration to obtain a more realistic sea condition. The influence of random wave phases should be taken into consideration when the analyzed points are located near the instability boundary. Stability charts for different wave peak periods are various. Stability charts are helpful for the parameter determination in design stage to better adapt to sailing condition. Last, ship variables are analyzed according to stability charts by a statistical approach. The increase of the metacentric height will help improve ship stability.

关键词： parametric instability parametric rolling multi-frequency irregular waves Ince-Strutt stability chart

Asymptotic inference for AR(1) panel data

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Applied Mathematics(A Journal of Chinese Universities) 2020年第3期35卷 265-280页

作者： SHEN Jian-fei PANG Tian-xiao School of Mathematical Sciences Zhejiang UniversityHangzhou 310027China

A general asymptotic theory is given for the panel data AR(1) model with time series independent in different cross sections. The theory covers the cases of stationary process, local to unity process, unit root process, mildly integrated, mildly explosive and explosive processes. It is assumed that the cross-sectional dimension and time-series dimension are respectively N and T. The results in this paper illustrate that whichever the process is, with an appropriate regularization, the least squares estimator of the autoregressive coefficient converges in distribution to a normal distribution with rate at least O(N-1/3). Since the variance is the key to characterize the normal distribution, it is important to discuss the variance of the least squares estimator. We will show that when the autoregressive coefficient ρ satisfies |ρ| 1. ρ = 1 is the critical point where the convergence rate changes radically. The transition process is studied by assuming ρ depending on T and going to 1. An interesting phenomenon discovered in this paper is that, in the explosive case, the least squares estimator of the autoregressive coefficient has a standard normal limiting distribution in the panel data case while it may not has a limiting distribution in the univariate time series case.

关键词： AR(1)model Least squares estimator Limiting distribution Non-stationray Panel data

Information and knowledge behind data from underground rock grouting

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第6期13卷 1326-1339页

作者： fei xiao Qian Liu Zhiye Zhao Department of Civil Engineering Nanjing University of Aeronautics and AstronauticsNanjing210016China School of Civil and Environmental Engineering Nanyang Technological University50 Nanyang Avenue639798Singapore

Data related to the pre-grouting work of a large underground project are systematically analyzed to reveal the mechanism behind,to shed some light on the execution of practical grouting,and to enrich the theory of engineering *** is generally taken as an effective way for controlling nonignorable water seepage during underground rock *** various models have been developed to guide grouting design or to specify criteria for grouting stop,it does not change the fact that grouting is still highly ***,explanation of the current situation due to grouting complexity is given through step-by-step data analysis,where the impact on grouting parameters from the geological and hydrogeological conditions is investigated,and the grouting features of two tunnels located at the same depth below the sea surface are compared and ***,the data from individual grout hole are used to construct the regional geological conditions via inverse *** is found that grouting of fractured rock masses is accompanied with great uncertainty,and field grouting data can contribute significantly to a better understanding of the regional geological conditions around an underground tunnel or rock cavern.

关键词： Field grouting data Water seepage Rock grouting Inverse modelling Data analytics Geological conditions