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HMvisor: dynamic hybrid memory management for virtual machines

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Science China(Information Sciences) 2021年第9期64卷 74-89页

作者： dang YANG Haikun LIU Hai JIN Yu ZHANG National Engineering Research Center for Big Data Technology and System Services Computing Technology and System Lab Cluster and Grid Computing LabSchool of Computer Science and Technology Huazhong University of Science and Technology

Emerging non-volatile memory(NVM) technologies promise high density, low cost and dynamic random access memory(DRAM)-like performance, at the expense of limited write endurance and high write energy consumption. It is more practical to use NVM combining with the traditional DRAM. However, the hybrid memory management such as page migration becomes more challenging in a virtualization environment because virtual machines(VMs) are unaware of the memory heterogeneity. In this paper, we propose HMvisor, a hypervisor and VM coordinated hybrid memory management mechanism to better utilize DRAM and NVM resources. HMvisor exposes the memory heterogeneity to VMs by mapping virtual NUMA nodes to different physical NUMA nodes. We propose a lightweight and efficient page migration mechanism by decoupling page hotness tracking from page migration. HMvisor performs those operations in the hypervisor and VMs separately, without disrupting the execution of VMs. We also propose a memory resource trading policy to adjust the capacity of DRAM and NVM for each VM, with the monetary cost unchanged. We implement our prototype system based on QEMU/KVM and evaluate it with several benchmarks. Experimental results show that HMvisor can reduce 50% of write traffic to NVM with less than 5% performance overhead. Moreover, the hybrid memory adjustment scheme in HMvisor can significantly improve application performance by up to 30×.

关键词： hypervisor virtual machine non-volatile memory hybrid memory management

Effects of afforestation on soil carbon and its fractions:a case study from the Loess Plateau,China

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Journal of Forestry Research 2018年第5期29卷 1291-1297页

作者： Yang Gao Peng dang Zhong Zhao Key Laboratory of Environment and Ecology in Western China of Ministry of Education College of ForestryNorthwest A&F University

Afforestation has been implemented to reduce soil erosion and improve the environment of the Loess Plateau,*** it increased soil organic carbon（SOC）,the stability of the increase is ***,the variations of soil inorganic carbon（SIC） following afforestation needs to be *** planting Robinia pseudoacacia,Pinus tabuliformis,and Hippophae rhamnoides on bare land on the Loess Plateau,total soil carbon（TSC） was measured and its two components,SIC and SOC,as well as the light and heavy fractions within SOC under bare lands and woodlands at the soil surface（0–20 cm）.The results show that TSC on bare land was 24.5 Mg ha^（-1） and significantly increased to 51.6 Mg ha^（-1） for ***,47.0 Mg ha^（-1） for *** and 39.9 Mg ha^（-1） for *** accumulated total soil carbon under ***,***,and ***,the heavy fraction（HFSOC） accounted for 65.2,31.7 and 76.2%,respectively; the light fraction（LF-SOC） accounted for 18.0,52.0 and 4.0%,respectively; SIC occupied 15.6,15.3 and 19.7%,*** accumulation rates of TSC under ***,***,and *** reached159.5,112.4 and 102.5 g m^（-2） a^（-1）,*** results demonstrate that afforestation on bare land has high potential for soil carbon accumulation on the Loess *** the newly sequestrated total soil carbon,the heavy fraction（HF-SOC） with a slow turnover rate accounted for a considerably high percentage,suggesting that significant sequestrated carbon can be stored in soils following ***,afforestation induces SIC *** its contribution to TSC accumulation was less than SOC,overlooking it may substantially underestimate the capacity of carbon sequestration after afforestation on the Loess Plateau.

关键词： Soil carbon sequestration Soil organic carbon Organic carbon fractions Soil inorganic carbon Afforestation

An Improved Kalman Filter Positioning Method in NLOS Environment

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China Communications 2019年第12期16卷 84-99页

作者： Zhanjun Hao Beibei Li Xiaochao dang College of Computer Science and Engineering Northwest Normal UniversityLanzhou 730070China Gansu Province Internet of Things Engineering Research Center Lanzhou 730070China

In the precision positioning system, NLOS(Non Line of Sight) propagation and clock synchronization error caused by multiple base stations are the main reasons for reducing the reliability of communication and positioning accuracy. So, in the NLOS environment, it has an important role to eliminate the clock synchronization problem in the positioning system. In order to solve this problem, this paper proposes an improved Kalman filter localization method NLOS-K(Non Line of Sight-Kalman filter). First, the maximum likelihood estimation algorithm is used to iterate. Then, the Kalman filter algorithm is implemented and the Kalman gain matrix is redefined. The clock drift is compensated so that the clock between the master and slave base stations remains synchronized. The experimental results show that in the non-lineof-sight environment, compared with other algorithms, the positioning accuracy error of the improved algorithm is about 5 cm, and the accuracy compared with other algorithms is 97%. In addition, the influence of bandwidth and spectral density on the method is analyzed, and the accuracy and stability of positioning are improved as a whole.

关键词： NLOS clock synchronization Kalman filtering maximum likelihood estimation spectral density

Further Results on Overlarge Sets of Kirkman Triple Systems

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Acta Mathematica Sinica,English Series 2009年第3期25卷 419-434页

作者： Lan dang YUAN Qing De KANG College of Career Technology Hebei Normal University Shijiazhuang 050031 P. R. China Institute of Mathematics Hebei Normal University Shijiazhuang 050016 P. R. China

In this paper, we introduce a new concept -- overlarge sets of generalized Kirkman systems （OLGKS）, research the relation between it and OLKTS, and obtain some new results for OLKTS. The main conclusion is： If there exist both an OLKF（6^k） and a 3-OLGKS（6^k-1,4） for all k ∈{6,7,...,40}／{8,17,21,22,25,26}, then there exists an OLKTS（v） for any v ≡ 3 （mod 6）, v ≠ 21. As well, we obtain the following result： There exists an OLKTS（6u ＋ 3） for u = 2^2n-1 - 1, 7^n, 31^n, 127^n, 4^r25^s, where n ≥ 1,r＋s≥ 1.

关键词： Kirkman frame Kirkman triple system overlarge set (2 1)-resolvable Steiner quadruplesystem

Spectra of rational orthonormal systems

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Science China Mathematics 2019年第10期62卷 1961-1976页

作者： Qiuhui Chen Pei dang Tao Qian Department of Mathematics College of Mathematics and InformaticsSouth China Agricultural UniversityGuangzhou510642China Faculty of Information Technology Macao University of Science and TechnologyMacaoChina Macao Institute of Systems Engineering Macao University of Science and TechnologyMacaoChina

We use the Weyl correspondence approach to investigate the spectral operators of the Laguerre and the Kautz systems. We show that the basic functions in the Laguerre and the Kautz systems are the eigenvectors of modified Sturm-Liouville operators. The results are further generalized to multiple parameters of one complex variable in both the unit disc and the upper half-plane contexts.

关键词： spectral operator Laguerre and Kautz systems TM system Caley transform Heisenberg group Weyl correspondence

Exploring the pivotal role of silver(Ⅰ) additives in palladium-catalyzed NH_(2)-directed C(sp^(3))–H arylation reactions

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Chinese Chemical Letters 2021年第12期32卷 3980-3983页

作者： Ning Zhao Xiaojiao Jin Yanfeng dang Tianjin Key Laboratory of Molecular Optoelectronic Sciences Department of ChemistryTianjin UniversityTianjin 300072China

Combined theoretical and experimental studies have explained the mechanism of Pd-catalyzed δ-C(sp^(3))-H arylation of primary amines. Instead of the monomeric Pd mechanism, our research unveils that all steps including C–H activation, oxidative addition, and reductive elimination take place via the heterodimeric Pd–Ag intermediates and transition states. Experimentally, the active heterodimeric Pd–Ag species were detected by mass spectrometry, which further confirms the proposed heterodimeric mechanism. Insight gained through this study reveals the synergistic manner of palladium catalysis and silver(Ⅰ)additives in native NH;-directed C–H activation and C–C coupling reactions.

关键词： Palladium catalysis Silver(Ⅰ)additive C(sp^(3))–H arylation Heterodimeric mechanism DFT study

NEW WEIGHTED MULTILINEAR OPERATORS AND COMMUTATORS OF HARDY-CESàRO TYPE

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Acta Mathematica Scientia 2015年第6期35卷 1411-1425页

作者： Ha Duy HUNG Luong dang KY High School for Gifted Students Hanoi National University of Education Applied Analysis Research Group Faculty of Mathematics and StatisticsTon Duc Thang University

This paper deals with a general class of weighted multilinear Hardy-Cesaro op- erators that acts on the product of Lebesgue spaces and central Morrey spaces. Their sharp bounds are also obtained. In addition, we obtain sufficient and necessary conditions on weight functions so that the commutators of these weighted multilinear Hardy-Cesaro oper- ators （with symbols in central BMO spaces） are bounded on the product of central Morrey spaces. These results extends known results on multilinear Hardy operators.

关键词： Hardy-Ces^ro operators Hardy's inequality multilinear Hardy operator weig-hted Hardy-Littlewood averages

Cell trapping and patterning using dielectric-structure-assisted negative dieletrophoresis

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Science China(Technological Sciences) 2013年第4期56卷 1001-1007页

作者： dang Hua DING YingTao WANG ZheYao School of Information and Electronics Beijing Institute of Technology Institute of Microelectronics Tsinghua University

This paper reports a cell trapping and patterning method using dielectric-pattern-assisted negative dielectrophoresis (dnDEP) that can achieve high-density cell arrays and complicated cell *** dnDEP device consists of two planar metal electrodes and a patterned dielectric layer sandwiched *** dielectric patterns generate non-uniform electric fields when an ac voltage is applied on the two electrodes,and the interaction of polarizable cells and the non-uniform electric fields imposes negative DEP forces on the cells,pushing them to the patterns in the dielectric *** this dnDEP device,human lymphoma cells were successfully patterned in high-density microwell arrays and stellate *** to the three-dimensional configuration and the small distance between the electrodes,cell trapping and patterning can be implemented with a voltage of 10 *** dnDEP device has the advantages of simple configuration,low actuating voltage,and the compatibility with high conductivity physiological media for cell culturing.

关键词： cell patterning dielectric negative dielectrophoresis (DEP) trapping

COMPUTATION OF TURBULENT FLOW IN TWO-DIMENSIONAL IRREGULAR DOMAIN INCLUDING ROTATION EFFECTS

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Journal of Hydrodynamics 1991年第3期3卷 10-18页

作者： Yin-yi, dang Xiang-lin, Fei Xi'an Jiaotong Univ Xi'an Shanxi China

A finite volume method is employed to predict the turbulent flow in irregular domains. In handling the irregular solution domain an algebraic nonorthogonal transformation along with the orthogonal body-surface coordinate is presented, which avoids the task of numerically generating the grid and also extends the scope of solution domain as compared with that of [1]. The modified K-Ε turbulence model is adopted to account for the Coriolis force caused by the system rotation. Three examples with or without rotation effects are presented.

关键词： Computers Applications Fluid Mechanics Hydrodynamics Mathematical Models Mechanical Variables Measurement Flow