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数学杂志 2005年第3期25卷 299-302页

作者：夏爱桃湖南公安高等专科学校基础课部湖南长沙410006

根据幂级数系数重排级不变的充要条件,对比研究了幂级数系数的重排与此级数的和函数的型之间的关系,得到了幂级数系数重排型不变的一些必要条件.

关键词：重排幂级数型必要条件

等通道转角挤压工艺参数对镁合金组织与性能的影响

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轻金属 2009年第2期 42-45,48页

作者：艾桃桃冯小明陕西理工学院材料科学与工程学院陕西汉中723003

镁合金具有密排六方结构,塑性变形能力差大大限制了其应用。等通道转角挤压技术(Equal-channel AngularPressing,ECAP)是一种通过强烈塑性变形而获得大尺寸亚微米或纳米级块体金属的有效方法。经ECAP技术加工后,原始组织得以细化,铸造... 详细信息

镁合金具有密排六方结构,塑性变形能力差大大限制了其应用。等通道转角挤压技术(Equal-channel AngularPressing,ECAP)是一种通过强烈塑性变形而获得大尺寸亚微米或纳米级块体金属的有效方法。经ECAP技术加工后,原始组织得以细化,铸造组织缺陷被消除,综合性能大大提高。但ECAP技术对镁合金组织与性能的影响工艺参数较多,主要参数包括模具结构、挤压路径、挤压道次、挤压温度以及挤压速度。本文旨在阐述ECAP各工艺参数对镁合金组织与性能的影响。

关键词：等通道转角挤压镁合金组织性能变形

Track-before-detect for bistatic radar based on pseudo-spectrum

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Chinese Journal of Aeronautics 2024年第1期37卷 236-246页

作者： tao HAN Gongjian ZHOU School of Electronics and Information Engineering Harbin Institute of TechnologyHarbin 150001China Key Laboratory of Marine Environmental Monitoring and Information Processing Ministry of Industry and Information TechnologyHarbin 150001China

Track-Before-Detect(TBD) is an efficient method to detect dim targets for radars. Conventional TBD usually follows an approximate motion model of the target, which may cause an inaccurate integration of the target energy. A TBD technique on basis of pseudo-spectrum in mixed coordinates adopting an accurate motion model for bistatic radar system is developed in this *** predicted position in bistatic polar plane is derived according to a nonlinear function that exactly describes the constant Cartesian velocity motion. Then around the predicted position, a pseudo-spectrum is formulated and its samples are accumulated to the integration frame for energy integration. The evolution of the state and the procedure of accumulation of the target energy are derived elaborately. The superior performance of the proposed method is demonstrated by some simulations.

关键词： Weak target detection Bistatic radar Track-before-detect Pseudo-spectrum Multiframe integration

Heat Transfer and Friction Characteristics of Printed Circuit Heat Exchangers with Different Channel Structures for S-CO_(2) Power System

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Journal of Thermal Science 2024年第3期33卷 1132-1147页

作者： JIANG tao LI Mingjia Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an710049China School of Mechanical Engineering Beijing Institute of TechnologyBeijing100081China

Printed circuit heat exchanger(PCHE)has been widely used in supercritical carbon dioxide(S-CO_(2))power systems because of its high heat transfer efficiency and good ***,due to the large variety of PCHE configurations,channel selection in practical applications lacks a ***,this paper discussed the heat transfer and friction characteristics and the synergy of three fields in the channel under the guidance of the field synergy principle for four typical PCHE ***,the comprehensive performance of four channels was ***,the heat transfer and friction factor correlations for S-CO_(2)in four channels were *** findings demonstrate that the synergy of velocity and pressure fields of the straight channel PCHE is better(β≈180°),so its resistance loss is relatively *** zigzag and sinusoidal wavy channels and the airfoil fins can reduce the angle a between the temperature gradient and velocity,thus enhancing the heat *** sinusoidal wavy channel can reduce flow resistance compared to the zigzag channel due to the rounded *** streamlined airfoil structure can guide the flow and reduce backflow,thus reducing resistance *** the range of Re studied in this paper,the maximum error of the proposed heat transfer and friction factor correlations of PCHE is 7.0%,which shows good fitting *** research in this paper can provide a reference for the selection and design of PCHE with different channel configurations.

关键词： printed circuit heat exchanger supercritical carbon dioxide typical channel structure field synergy analysis

Gas-surface interaction features under effects of gas-gas molecules interaction in high-speed flows

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Chinese Journal of Aeronautics 2024年第5期37卷 228-242页

作者： Ruiling tao Zhihui WANG School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

Understanding interactions between gas molecules and solid surface is key to the aerodynamic design of high-speed,high-altitude aerospace vehicles,but there is a large dispersion of gas-surface interaction parameters or namely accommodation *** uncertainty results partly from different considerations of the interaction between gas molecules in various experimental and numerical *** this study,effects of gas-gas molecules interaction are systematically discussed by comparing two different approaches of molecular dynamics simulation of high-speed argon molecules scattering on a graphite *** popularly-used“single scattering”approach repeats the scattering process of a single gas molecule without considering the gas-gas molecules *** newly-developed“continual scattering”approach continually shoots gas molecules at the surface,considering collisions between gas molecules in addition to gas molecules’collisions with ***-surface interaction features in the two approaches are compared and discussed under various affecting factors including rarefaction degree,gas-surface interaction strength,surface temperature and incident *** is shown that these two approaches usually produce different accommodation coefficients,and the corresponding mechanisms are *** study could help clarify some doubts about the selection of accommodation coefficients in engineering practice,and also provide an instruction on design of an appropriate molecular dynamics simulation approach.

关键词： Gas-surface interaction Molecular dynamics Accommodation coefficient Aerospace vehicles High-speed flow

On m-ovoids of finite classical polar spaces with an irreducible transitive automorphism group

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Science China Mathematics 2024年第3期67卷 683-712页

作者： tao Feng Weicong Li Ran tao School of Mathematical Sciences Zhejiang UniversityHangzhou 310027China Department of Mathematics and National Center for Applied Mathematics Shenzhen Southern University of Science and TechnologyShenzhen 518055China Key Laboratory of Cryptologic Technology and Information Security Ministry of EducationShandong UniversityQingdao 266237China School of Cyber Science and Technology Shandong UniversityQingdao 266237China

In this paper, we classify the m-ovoids of finite classical polar spaces that admit a transitive automorphism group acting irreducibly on the ambient vector space. In particular, we obtain several new infinite familie... 详细信息

关键词： transitive m-ovoids irreducible action finite classical polar spaces primitive divisor

Atomically dispersed materials:Ideal catalysts in atomic era

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Nano Research 2024年第1期17卷 18-38页

作者： tao Gan Dingsheng Wang Department of Chemistry Tsinghua UniversityBeijing 100084China

Catalysts can accelerate the chemical reaction rate and effectively promote the molecules transformation,which is of great significance in the research of chemical industry and material *** extreme utilization of reactive sites has led to the emergence and development of atomically dispersed materials(ADMs).The highly active coordination unsaturated metal sites and fully utilized metal atoms make ADMs show great potential in catalytic *** adjustment of coordination environment and electronic structure provides more possibilities for constructing reactive centers with different *** review summarized the application and research progress of ADMs in different *** design strategy and structure–activity relationship of ADMs for specific reactions were summarized and ***,we also provided advices for the challenges and opportunities faced by ADMs in catalytic reactions.

关键词： atomically dispersed materials catalysis organic synthesis battery sensor enzyme

Holder continuous weak solutions of the 2D Boussinesq equation with thermal diffusion

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Science China Mathematics 2024年第8期67卷 1777-1806页

作者： Tianwen Luo tao tao Liqun Zhang Yau Mathematical Sciences Center Tsinghua UniversityBeijing 100084China School of Mathematics Shandong UniversityJinan 250100China Institute of Mathematics Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China

We show the existence of Holder continuous periodic weak solutions of the 2D Boussinesq equation with thermal diffusion which satisfy the prescribed kinetic *** precisely,for any smooth e(t):[0,1]→R+andε∈(0,110),there exist v∈C 110−ε([0,1]×T2)andθ∈C 1,120−εt 2 C 2,1 x 10−ε([0,1]×T2),which satisfy(1.1)in the sense of distribution and e(t)=ˆT2|v(t,x)|2 dx,∀t∈[0,1].

关键词： 2D Boussinesq equation with thermal diffusion Holder continuous periodic weak solutions prescribed kinetic energy

热处理对原位烧结合成Mo_2FeB_2陶瓷组织与性能的影响

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材料热处理学报 2010年第4期31卷 6-9页

作者：李文虎徐峰艾桃桃冯小明陕西理工学院材料科学与工程学院陕西汉中723003

用X射线衍射仪、扫描电镜、万能材料试验机研究了真空液相烧结制备的Mo2FeB2金属陶瓷热处理后的组织与性能。结果表明,真空液相烧结Mo2FeB2金属陶瓷主要由Mo2FeB2、MoB2、Fe2B相和铁基粘结相组成,经700～1000℃热处理后,MoB2、Fe2B相逐... 详细信息

用X射线衍射仪、扫描电镜、万能材料试验机研究了真空液相烧结制备的Mo2FeB2金属陶瓷热处理后的组织与性能。结果表明,真空液相烧结Mo2FeB2金属陶瓷主要由Mo2FeB2、MoB2、Fe2B相和铁基粘结相组成,经700～1000℃热处理后,MoB2、Fe2B相逐渐转化为Mo2FeB2相,并且Mo2FeB2晶粒细化,呈规则块状均匀分布在铁基粘结相中。Mo2FeB2金属陶瓷在700～1000℃范围内随热处理温度的升高,弯曲强度、断裂韧性与维氏硬度均增加,当热处理温度为1000℃时,其值分别达到1182.42MPa、13.59MPa·m1/2、9.114GPa,与未处理试样相比,分别增加了5.4%、6.0%、7.0%。

关键词： Mo2FeB2 微观组织力学性能热处理

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基于希尔伯特-黄变换的AEP去噪方法

计算机工程 2011年第19期37卷 163-165页

作者：张爱桃李彬王涛南方医科大学生物医学工程学院广州510515

在高刺激率模式下,采用去卷积方法提取暂态的听觉诱发电位存在噪声敏感的问题。为此,提出一种结合希尔伯特-黄变换(HHT)与总体相关的去噪方法。利用HHT方法提取有用信号,通过总体相关方法区分混叠在同一频率段的信号和噪声,获得相关性... 详细信息

在高刺激率模式下,采用去卷积方法提取暂态的听觉诱发电位存在噪声敏感的问题。为此,提出一种结合希尔伯特-黄变换(HHT)与总体相关的去噪方法。利用HHT方法提取有用信号,通过总体相关方法区分混叠在同一频率段的信号和噪声,获得相关性强的成分。实验结果表明,该方法能在不增加刺激个数的情况下,使得平均信号的信噪比提高约4倍,且不需要信号的先验知识和人为干预,便于应用。

关键词：听觉诱发电位希尔伯特-黄变换经验模态分解总体相关技术非线性阈值