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Chinese Journal of Chemical Physics 2015年第5期28卷 -页

作者： li-li Xing Xiao-yuan zhang Zhan-dong Wang Shuang li li-dong zhang National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei 230029 China

Hydroperoxymethyl formate is a crucial intermediate formed during the low-temperature oxi- dation of dimethyl ether. The decomposition pathways of HOOCH2OCHO were calculated at QCISD(T)/CBS//B3LYP/6-311++G(d, p) level. The temperature- and pressure-dependent rate constants are computed using microcanonical variational transition state theory coupled with the RRKM/master equation calculations. The calculations show that a pathway leads to the formation of formic acid and a Criegee intermediate does exist, besides the direct dissociation channel to OH and OCH2OCHO radicals. However, formation of the Criegee intermediate has never been considered as an intermediate in dimethyl ether combustion be- fore. The computed rate constants indicate that the newly confirmed pathway is competitive to the direct dissociation route and it is promising to reduce the low-temperature oxidation reactivity. Also electronic effect of groups, e. g. -CHO and O atom, is taken into account. Moreover, Hirshfeld atomic charge and natural bond order analysis are performed to explain this phenomenon from a perspective of chemical nature.

关键词： Hydroperoxymethyl formate RRKM/master equation calculations Low temperature oxidation Dimethyl ether Chain branching

High throughput bandwidth optimized VLSI design for motion compensation in AVS HDTV decoder

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第6期9卷 822-832页

作者： Kai LUO dong-xiao li Ming zhang Department of lnformation Science and Electronic Engineering Zhejiang University Hangzhou 310027 China

In this paper we present a motion compensation (MC) design for the newest Audio Video coding Standard (AVS) of China. Because of compression-efficient techniques of variable block size (VBS) and sub-pixel interpolation, intensive pixel calculation and huge memory access are required. We propose a parallel serial filtering mixed luma interpolation data flow and a three-stage multiplication free chroma interpolation scheme. Compared to the conventional designs, the integrated architecture supports about 2.7 times filtering throughput. The proposed MC design utilizes Vertical Z processing order for reference data re-use and saves up to 30% memory bandwidth. The whole design requires 44.3k gates when synthesized at 108 MHz clock frequency using 0.18-μm CMOS technology and can support up to 1920×1088@30 fps AVS HDTV video decoding.

关键词： Audio Video coding Standard (AVS) Motion compensation (MC) Interpolation VLSI Architecture

Identification of Intermediates in Pyridine Pyrolysis with Molecular-beam Mass Spectrometry and Tunable Synchrotron VUV Photoionization

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Chinese Journal of Chemical Physics 2009年第2期22卷 204-209页

作者： Xin Hong Tai-chang zhang li-dong zhang Fei Qi National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei 230029 China

The pyrolysis of pyridine （5.26% pyridine in argon） was performed with tunable synchrotron vacuum ultraviolet photoionization and molecular-beam mass spectrometry technique at the temperature range of 1255-1765 K at 267 Pa. About 20 products and intermediates, containing major species H2, HCN, C2H2, C5H3N, C4H2, and C3H3N, were identified by near-threshold measurements of photoionization mass spectra and their mole fractions vs. temperatures were estimated. The major reaction pathways are analyzed based on the experimental observations.

关键词： Pyridine pyrolysis Intermediate Tunable synchrotron VUV photoionization Molecular-beam mass spectrometry

Theoretical Study of the AIEt3-Promoted Tandem Reductive Rearrangement of Epoxides

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Chinese Journal of Chemical Physics 2008年第6期21卷 547-554页

作者： li-dong zhang Hui-jun Guo Yang Pan Fei Qi National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei 230029 China

The AIEt3-promoted tandem reductive rearrangement reactions of epoxides was studied at B3LYP/6- 31C（d,p） level. For the model compound α-hydroxy epoxides, two possible reaction pathways Ⅰ and Ⅱ were calculated. The main difference is the order of ethylene release and six- to five-member ring rearrangement. The ring contraction rearrangement in pathway Ⅰ is the first step and this step is the rate controlling step with a free energy barrier of 116.62 kJ/mol. For pathway Ⅱ, the ethylene release occurs first, and is followed by a six-member ring opening reaction which is the rate controlling step, and the barrier is 251.38 kJ/mol. The reason for such high barrier is that the ethylene release results in the following reaction being more difficult. The results show that pathway Ⅰ （C-C rearrangement and then ethylene release） is more favorable, which is consistent with experimental results.

关键词： AIEt3 Rearrangement Density functional theory Diol Epoxide

A New Stilbene from Cercis chinensis Bunge

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Journal of Integrative Plant Biology 2005年第8期47卷 1021-1024页

作者： Yuan li dong-Ming zhang Shi-Shan YU Institute of Materia Medica Chinese Academy of Medical Sciences and Peking Union Medical College Beijing 100050 China

To study new natural products, we used ODS （YMC, Kyoto, Japan） and silica gel column chromatography to separate compounds in Cercis chinensis Bunge （Leguminosae）. A new stilbene, trans- 3, 5, 3＇, 4＇-tetrahydroxy-4-methylstilbene （1）, along with 10 known compounds, namely piceatannol （2）, dihydromyricetin （3）, catechin （4）, dihydrorobinetin （5）, menisdaurin （6）, lithospermoside （7）, teatannin （8）, dasycarponin （9）, β-sitosterol （10）, and daucosterin （11）, was isolated from C. chinensis. Their structures were elucidated on the basis of spectroscopic evidence. Compounds 2-6 and 9 were isolated from the genus Cercis linn. for the first time.

关键词： Cercis chinensis Leguminosae trans-3, 5, 3', 4'-tetrahydroxy-4-methylstilbene.

Motion planning of a quadrotor robot game using a simulation-based projected policy iteration method

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Frontiers of Information Technology & Electronic Engineering 2019年第4期20卷 525-537页

作者： li-dong zhang Ban WANG Zhi-xiang liU You-min zhang Jian-liang AI Department of Aeronautics and Astronautics Fudan University Department of Mechanical Industrial and Aerospace Engineering Concordia University

Making rational decisions for sequential decision problems in complex environments has been challenging researchers in various fields for decades. Such problems consist of state transition dynamics, stochastic uncertainties,long-term utilities, and other factors that assemble high barriers including the curse of dimensionality. Recently, the state-of-the-art algorithms in reinforcement learning studies have been developed, providing a strong potential to efficiently break the barriers and make it possible to deal with complex and practical decision problems with decent performance. We propose a formulation of a velocity varying one-on-one quadrotor robot game problem in the threedimensional space and an approximate dynamic programming approach using a projected policy iteration method for learning the utilities of game states and improving motion policies. In addition, a simulation-based iterative scheme is employed to overcome the curse of dimensionality. Simulation results demonstrate that the proposed decision strategy can generate effective and efficient motion policies that can contend with the opponent quadrotor and gather advantaged status during the game. Flight experiments, which are conducted in the Networked Autonomous Vehicles(NAV) Lab at the Concordia University, have further validated the performance of the proposed decision strategy in the real-time environment.

关键词： Reinforcement learning Approximate dynamic programming Decision making Motion planning Unmanned aerial vehicle

Theoretical Studies on the Reaction Kinetics of Methyl 2-Furoate with Hydroxyl Radical

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Chinese Journal of Chemical Physics 2022年第4期35卷 664-672,I0150页

作者： Wei He Jing Lu li-dong zhang Jing liu li-xia Wei College of Chemistry and Chemical Engineering Guangxi UniversityNanning 530004China College of Mechanical Engineering Guangxi UniversityNanning 530004China State Key Laboratory of Fire Science University of Science and Technology of ChinaHefei 230026China State Key Laboratory of Coal Combustion School of Energy and Power EngineeringHuazhong University of Science and TechnologyWuhan 430074China

Methyl 2-furoate(FAME2)is a model for the potential renewable biofuel of dimethyl furan-2,5-dicarboxylate,with the development of its new synthesis *** potential energy surfaces of H-abstractions and OHadditions between FAME2 and hydroxyl radical(OH)were studied using CCSD(T)/CBS//M062X/*** subsequent isomerization and decomposition reactions were also determined for the primary radicals *** results showed that H-abstraction on the branched methyl group was the dominant channel and that the OH-addition reactions on the furan ring had a significant pressure *** rate coefficients presented here provide important kinetic data to support future improvement of the combustion mechanism of FAME2,and present a sound basis for further research into practical fuels.

关键词： Furoate Theoretical calculation Hydroxyl Addition Abstraction

Photoionization and Dissociative Photoionization Study of Cholesterol by I R Laser Desorption/Tunable Synchrotron VUV Photoionization Mass Spectrometry

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Chinese Journal of Chemical Physics 2009年第2期22卷 129-133页

作者： Yang Pan li-dong zhang Hui-jun Guo Hao Yin Fei Qi National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei 230029 China Hefei National Laboratory for Physical Sciences at Microscale University of Science and Technology of China Hefei 230026 China

Elementary cholesterol was analyzed with IR laser desorption/tunable synchrotron vacuum ultraviolet photoionization mass spectrometry. An exclusive molecular ion of cholesterol is observed by near threshold single-photon ionization with high efficiency. Fragments are yielded with the increase of photon energy. The structures of various fragments are determined with commercial electron ionization time-of-flight mass spectrometry. Dominant fragmentation pathways are discussed in detail with the aid of ab initio calculations.

关键词： Cholesterol Mass spectrometry Laser desorption Photoionization Ab initio

Influence of heat treatment on microstructure and mechanical properties of Al/Al-Cu graded materials

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Acta Metallurgica Sinica(English Letters) 2011年第2期24卷 118-124页

作者： Qian CONG Fumin XU Yi TAN Xiaolei SHI Wei dong Jiayan li Junshan zhang School of Materials Science and Engineering Dalian University of Technology Dalian 116024 China

Five-layered Al/Al-Cu functionally graded material （FGM） was prepared by powder metallurgy technology, and the subsequent heat treatment was carried out for the graded material. The microstructures and distribution of Cu element under pressure sintering （F）, solution treatment （T4） and artificial aging treatment （T6） were investigated, and the Vickers hardness and flexural properties of different states were tested. The results showed that sintered compact with dense structure and compositional continuous change was obtained. The second-phase CuAl 2 was dispersively distributed along grain boundary of Al matrix. After solution treatment at 503 C for 3 h, CuAl 2 phase obviously decreased and dissolved into the Al matrix, and the flexural strength was thereupon enhanced to 228.5 MPa. With the subsequent aging treatment at 150 C for 15 h, the majority of flake shaped precipitates θ phases were uniformly distributed in the matrix. And the distribution of Cu element became gradual continuous compared to sintered compact. Meanwhile, the flexural strength increased further, which accompanied with the decline of plasticity.

关键词： Al/Al-Cu graded material Solution treatment Artificial aging Mechanical properties

Joint fuzzy background and adaptive foreground model for moving target detection

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Frontiers of Computer Science 2024年第2期18卷 93-106页

作者： Dawei zhang Peng WANG Yongfeng dong linhao li Xin li School of Artificial Intelligence Hebei University of TechnologyTianjin 300401China Lane Department of Computer Science and Electrical Engineering West Virginia UniversityMorgantownWV 26506-6109USA

Moving target detection is one of the most basic tasks in computer *** conventional wisdom,the problem is solved by iterative optimization under either Matrix Decomposition(MD)or Matrix Factorization(MF)*** utilizes foreground information to facilitate background *** uses noise-based weights to fine-tune the *** both noise and foreground information contribute to the recovery of the *** jointly exploit their advantages,inspired by two framework complementary characteristics,we propose to simultaneously exploit the advantages of these two optimizing approaches in a unified framework called Joint Matrix Decomposition and Factorization(JMDF).To improve background extraction,a fuzzy factorization is *** fuzzy membership of the background/foreground association is calculated during the factorization process to distinguish their contributions of both to background *** describe the spatio-temporal continuity of foreground more accurately,we propose to incorporate the first order temporal difference into the group sparsity constraint *** temporal constraint is adjusted *** foreground and the background are jointly estimated through an effective alternate optimization process,and the noise can be modeled with the specific probability *** experimental results of vast real videos illustrate the effectiveness of our *** with the current state-of-the-art technology,our method can usually form the clearer background and extract the more accurate ***-noise experiments show the noise robustness of our method.

关键词： matrixdecomposition matrix factorization generalized sparsity noise modeling