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Thermodynamic Analysis of a Mixed Refrigerant Ejector Refrigeration Cycle Operating with Two Vapor-liquid Separators

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Journal of Thermal Science 2018年第3期27卷 230-240页

作者： TAN Yingying CHEN youming WANG Lin School of Civil Engineering Hunan University Institute of Refrigeration and Air-Conditioning Henan University of Science and Technology

A mixed refrigerant ejector refrigeration cycle operating with two-stage vapor-liquid separators （MRERC2） is proposed to obtain refrigeration temperature at -40℃. The thermodynamic investigations on per- formance of MRERC2 using zeotropic mixture refrigerant R23/R134a are performed, and the comparisons of cycle performance between MRERC2 and MRERC1 CMRERC with one-stage vapor-liquid separator） are conducted. The results show that MRERC2 can achieve refrigeration temperature varying between -23.9℃ and -42.0℃ when ejector pressure ratio ranges from 1.6 to 2.3 at the generation temperature of 57.3-84.9℃. The parametric analysis indicates that increasing condensing temperature decreases coefficient of performance （COP） of MRERC2, and increasing ejector pressure ratio and mass fraction of the low boiling point component in the mixed refrigerant can improve COP of MRERC2. The MRERC2 shows its potential in utilizing low grade thermal energy as driving power to obtain low refrigeration temperature for the ejector refrigeration cycle.

关键词： Ejector Refrigeration Zeotropic Refrigerant Vapor-liquid Separator Refrigeration Temperature

Synchronization in a fractional-order dynamic network with uncertain parameters using an adaptive control strategy

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Applied Mathematics and Mechanics(English Edition) 2018年第3期39卷 353-364页

作者： Lin DU Yong YANG youming LEI Department of Applied Mathematics Northwestern Polytechnical University

This paper studies synchronization of all nodes in a fractional-order complex dynamic network. An adaptive control strategy for synchronizing a dynamic network is proposed. Based on the Lyapunov stability theory, this paper shows that tracking errors of all nodes in a fractional-order complex network converge to zero. This simple yet prac- tical scheme can be used in many networks such as small-world networks and scale-free networks. Unlike the existing methods which assume the coupling configuration among the nodes of the network with diffusivity, symmetry, balance, or irreducibility, in this case, these assumptions are unnecessary, and the proposed adaptive strategy is more feasible. Two examples are presented to illustrate effectiveness of the proposed method.

关键词： fractional-order chaotic system synchronization complex dynamic net-work adaptive control

Formaldehyde intermediate participating in the conversion of methanol to aromatics over zinc modified H-ZSM-5

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Journal of Energy Chemistry 2021年第3期30卷 174-178页

作者： youming Ni Wenliang Zhu Zhongmin Liu National Engineering Laboratory for Methanol to Olefins Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina Dalian National Laboratory for Clean Energy Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina

Metal-modified H-ZSM-5 has a high selectivity of aromatics in methanol to aromatics(MTA)reaction,which is often attributed to the metal promoting the aromatization of intermediate ***,the effect of methanol dehydrogenation on aromatics formation over these catalysts is rarely ***,we report that HCHO,which is formed by methanol dehydrogenation over Zn/H-ZSM-5 prepared by Zn impregnation,can participate in the synthesis of *** conversion can produce more aromatics than olefins(propylene or ethylene)conversion over Zn/H-ZSM-5,indicating the conventional MTA pathway including methanol-to-olefins and olefins-to-aromatics is not ***,an MTA mechanism including the conventional pathway and the methanol and HCHO coupling pathway is systematically proposed.

关键词： Methanol Formaldehyde Aromatics Zn H-ZSM-5

地方高校化学师范专业基础化学实验教学改革初探

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科教导刊 2018年第25期 120-122页

作者：申有名蒋倩婷周诗彪肖安国黄小兵张向阳湖南文理学院化学与材料工程学院湖南常德415000

以提高基础化学实验教学质量为目的,针对地方高校化学师范专业基础化学实验教学存在的问题,本文从实验教学内容改革、实验教学方法改革、实验考核方式改革、实验考核方式改革等方面阐述了师范专业基础化学实验教学改革,为提高地方高校... 详细信息

以提高基础化学实验教学质量为目的,针对地方高校化学师范专业基础化学实验教学存在的问题,本文从实验教学内容改革、实验教学方法改革、实验考核方式改革、实验考核方式改革等方面阐述了师范专业基础化学实验教学改革,为提高地方高校化学师范专业基础化学实验教学提供了参考。

关键词：地方高校化学师范基础化学实验教学改革

Adaptive Wavelet Solution to the Stokes Problem

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Acta Mathematicae Applicatae Sinica 2008年第4期24卷 613-626页

作者： Ying-chun Jiang youming Liu College of Mathematics and Computer Sciences Guilin University of Electronic Technology Cuilin 541004 China Department of Applied Mathematics Beijing University of Technology Beijing 100022 China

This paper deals with the design and analysis of adaptive wavelet method for the Stokes problem. First, the limitation of Richardson iteration is explained and the multiplied matrix M0 in the paper of Bramble and Pasciak is proved to be the simplest possible in an appropiate sense. Similar to the divergence operator, an exact application of its dual is shown; Second, based on these above observations, an adaptive wavelet algorithm for the Stokes problem is designed. Error analysis and computational complexity are given; Finally, since our algorithm is mainly to deal with an elliptic and positive definite operator equation, the last section is devoted to the Galerkin solution of an elliptic and positive definite equation. It turns out that the upper bound for error estimation may be improved.

关键词： Richardson iteration adaptive algorithm wavelets Stokes problem Galerkin solution

股权激励对货币薪酬的影响——“替代效应”抑或“福利效应”

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管理工程学报 2025年第2期39卷 57-78页

作者：沈真真李明辉南京大学商学院安徽大学商学院

关于股权激励与货币薪酬之间的关系,即股权激励实施后高管货币薪酬是下降还是上升,形成了替代效应和福利效应两种竞争性假说,现有研究对此缺乏相关经验证据。基于此,本文以A股非金融类上市公司2006年—2019年的数据为样本,采用PSM+DID... 详细信息

关于股权激励与货币薪酬之间的关系,即股权激励实施后高管货币薪酬是下降还是上升,形成了替代效应和福利效应两种竞争性假说,现有研究对此缺乏相关经验证据。基于此,本文以A股非金融类上市公司2006年—2019年的数据为样本,采用PSM+DID模型克服内生性问题,考察了股权激励计划的实施对高管货币薪酬的影响。结果表明,股权激励计划实施后,高管货币薪酬不降反升。股权激励不会替代货币薪酬,反而会促进货币薪酬增加,表现为福利效应。因此,上市公司很难利用股权激励来抑制高管薪酬的过快增长,管理层可以利用股权激励获取私人利益。进一步研究发现,福利效应存在于股权激励有效期较长、激励强度较大的公司,而股权激励标的不会影响股权激励与货币薪酬之间的关系。本文通过异质性分析发现,股权激励的福利效应仅存在于管理层权力较小、有管理层异常离职和外部审计质量较差的公司。本文从薪酬结构的角度提供了股权激励实施效应的经验证据,丰富了股权激励与货币薪酬间互动关系的研究。

关键词：股权激励货币薪酬替代效应福利效应

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Wavelets with Differential Relation

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Acta Mathematica Sinica,English Series 2011年第5期27卷 1011-1022页

作者： Zhi-Tao CHUANG youming LIU Department of Applied Mathematics Beijing University of Technology Beijing 100124 P. R. China

Divergence-free wavelets are successfully applied to numerical solutions of Navier-Stokes equation and to analysis of incompressible flows. They closely depend on a pair of one-dimensional wavelets with some differential relations. In this paper, we point out some restrictions of those wavelets and study scaling functions with the differential relation; Wavelets and their duals are discussed; In addition to the differential relation, we are particularly interested in a class of examples with the interpolatory property; It turns out there is a connection between our examples and Micchelli＇s work.

关键词： Differential relation interpolation wavelets scaling functions symmetry

Microwave-assisted synthesis,crystal structure and toxicity of L-aspartic acid zinc spiral linear supramolecular polymer

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Science China Chemistry 2004年第4期47卷 295-300页

作者： ZHANG youming LIN Qi WEI Taibao College of Chemistry and Chemical Engineering Gansu Key Laboratory of Polymer Materials Northwest Normal University Lanzhou730070China College of Chemistry and Chemical Engineering Gansu Key Laboratory of Polymer Materials Northwest Normal University Lanzhou730070China College of Chemistry and Chemical Engineering Gansu Key Laboratory of Polymer Materials Northwest Normal University Lanzhou730070China

L-aspartic acid zinc was synthesized by a rapid and convenient method in high yield under microwave conditions, and its single crystal structure was analyzed by X-ray diffraction. The structure unit of the title compound is [Zn(L-Asp)(H2O)2]·H2O, which is a bicyclo-complex forming a spiral linear polymer via coordination bonds. The spiral linear polymers are assembled as a three-dimensional supramolecule by intermolecular hydrogen bonds. The crystal belongs to the orthorhombic crystal system, P2(1)2(1)2(1) space group, a=0.7830(3) nm, b=0.9369(4) nm, c=11.599(5) nm, α=β=γ=90.00°, V=0.8509(6) nm3, Z=4, Dc=1.955 g/cm3, F(000)=512, μ=2.289. The toxicity of the title compound is lower than that of glutamic acid zinc and zinc sulfate. Keywords L-aspartic acid - zinc - microwave - supramolecule - toxicity

关键词： L-aspartic acid zinc microwave supramolecule toxicity

Wavelet estimations for density derivatives

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Science China Mathematics 2013年第3期56卷 483-495页

作者： LIU youming WANG HuiYing Department of Applied Mathematics Beijing University of Technology School of Applied Mathematics Central University of Finance and Economics

Donoho et al. in 1996 have made almost perfect achievements in wavelet estimation for a density function f in Besov spaces Bsr,q(R). Motivated by their work, we define new linear and nonlinear wavelet estimators flin,nm, fnonn,m for density derivatives f(m). It turns out that the linear estimation E(‖flinn,m-f(m)‖p) for f(m) ∈ Bsr,q(R) attains the optimal when r≥ p, and the nonlinear one E(‖fnonn,m-f(m)‖p) does the same if r≤p/2(s+m)+1 . In addition, our method is applied to Sobolev spaces with non-negative integer exponents as well.

关键词： wavelet estimators optimality Besov spaces Sobolev spaces density derivative