Al单晶的结合能和晶格常数的第一性原理计算研究

基于密度泛函理论框架下平面波赝势法的VASP软件包可以根据任意给定的一个晶胞棱边长度在原胞内求解Kohn-Sham方程,并算出相应的结合能,当结合能为最小值时,整个原胞的结构最为稳定,此时原胞的长度即为晶格常数。我们采用此方法计算了Al单晶的结合能和晶格常数,计算的结果与实验吻合得很好

国产XBT海上比测方法研究及结果分析

随着国产投弃式温深仪(XBT)性能的提高,其使用范围和规模也逐步扩大,受某专项办的委托,厦门大学在南海东北部开展了"海洋监测设备适用性检验规范及海上试验研究(国家863计划)"项目,针对海洋技术领域研发的技术较为成熟、具备产品化条件的XBT开展检验与验证,对国产XBT的性能和实际使用情况进行分析和总结。试验中,在不同站点进行温盐深仪(CTD)现场测量,以此数据为真值对国产和进口XBT精度做评估。在较高速度走航测量时,则以进口XBT数据为参照,对国产XBT进行评估。试验结果表明,国产XBT整体上表现良好,成功率大概为80%,有些型号的国产XBT精度与进口XBT精度接近,但国产XBT无效剖面较多。同时也发现,进口XBT的精度无法满足预期比测的要求,不能准确计算出国产XBT精度,但结果仍然具有参考价值。本次试验可以为国产XBT的规模化应用和推广提供数据支持,也可为其他型号XBT/XCTD/CTD等仪器的比测提供借鉴。国家重点研发计划资助项目(2016YFF0200900);;国家高技术研究发展计划(“863”计划)资助项目(2012AA091906);;促进海峡两岸科技合作联合基金资助项目(U1405233

First-Principles Study of Effect of Strain on the Band Structure of ZnO Monolayer

采用基于密度泛函理论的第一性原理计算对单层znO薄膜能带结构的应变调控进行了研究.计算结果表明:沿着之字形方向的压缩应变和扶椅形方向的拉伸应变对薄膜带隙的调控都是线性的,而且带隙调控的范围最大;相反地,在沿着之字形方向的拉伸应变和扶椅形方向的压缩应变的调控下,带隙则呈现出非线性的变化.对于双轴应变的拉伸与压缩,带隙的变化都是非线性的.这种通过不同的应变加载方式来实现对带隙不同程度的调控,对znO薄膜在光学和催化等领域的应用具有重要的指导意义.The effect of strain on the band structure of the ZnO monolayer has been investigated by firstprinciples calculations based on density functional theory.The results reveal that the band structure of the ZnO monolayer presents different dependences on three types of strain.The band gap linearly and steeply varies under uniaxial zigzag compressive strain and armchair tensile strain, while it shows nonlinear dependence on the other types of strain.Therefore, uniaxial zigzag compressive strain and armchair tensile strain should be the most effective to tune the band gap.This work has significant implications for application of strain to tune the optical and catalytic properties of ZnO nanofilms.国家自然科学基金(10702056;11204252); 四川省教育厅(12ZA072)资助项目~

Rare Earth Eu Doped PtRu/C Catalysts and Their Properties for Methanol Electrooxidation

Corresponding authors. Email: [email protected], [email protected]; Tel: +86-773-5846279, +86-592-2180181.[中文文摘]采用化学还原和热处理方法对商业PtRu/C催化剂进行稀土Eu掺杂,制备了不同Eu含量的PtRuEux/C催化剂.透射电子显微镜(TEM)、X射线能量色散光谱(EDX)、X射线衍射(XRD)和X射线光电子能谱(XPS)等方法表征催化剂的结果表明,Eu的掺杂未改变PtRu/C催化剂的平均粒径(约为3nm),并且Eu以金属和氧化物两种形态修饰PtRu表面.循环伏安和计时电流法测试显示,PtRuEux/C催化剂较商业PtRu/C对甲醇氧化具有更高的活性,其中PtRuEu0.3/C的活性最高.运用原位傅里叶变换红外(FTIR)光谱从分子水平研究了该催化剂对甲醇电催化氧化的反应过程,检测到甲醇在催化剂上解离吸附的吸附态产物是线型吸附态CO(COL),Eu的掺杂使COL的氧化电位降低,明显提高了催化剂的活性和抗CO毒化的能力.[英文文摘]Commercially available PtRu/C catalyst was doped with Eu by chemical reduction and sintering, resulting in PtRuEux/C catalysts with different Eu contents. The catalysts were characterized by transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Results showed that Eu doping did not change the average size of the PtRu/C catalysts (ca 3 nm), and their surfaces were modified by both Eu metal and oxide. Cyclic voltammetry and chronoamperometry demonstrated that the activity of the PtRuEux/C catalysts was higher than that of commercial PtRu/C for methanol electrooxidation. Among the PtRuEux/C catalysts, PtRuEu0.3/C exhibited the best performance. The electrocatalytic oxidation of methanol on the catalyst was further investigated by in situ Fourier transform infrared (FTIR) spectroscopy at molecular level. Results indicated that the adsorbed species derived from the dissociative adsorption of methanol on the catalysts were linear-bonded CO (COL). Eu doping decreased the oxidation potential of COL and thus significantly enhanced the activity of the catalysts and their tolerance to CO.国家自然科学基金(20833005,20828005);教育部留学回国人员科研启动基金; 厦门大学固体表面物理化学国家重点实验室开放课题;广西研究生教育创新计划项

中国物理海洋学研究70年：发展历程、学术成就概览

本文概略评述新中国成立70年来物理海洋学各分支研究领域的发展历程和若干学术成就。中国物理海洋学研究起步于海浪、潮汐、近海环流与水团,以及以风暴潮为主的海洋气象灾害的研究。随着国力的增强,研究领域不断拓展,涌现了大量具有广泛影响力的研究成果,其中包括:提出了被国际广泛采用的"普遍风浪谱"和"涌浪谱",发展了第三代海浪数值模式;提出了"准调和分析方法"和"潮汐潮流永久预报"等潮汐潮流的分析和预报方法;发现并命名了"棉兰老潜流",揭示了东海黑潮的多核结构及其多尺度变异机理等,系统描述了太平洋西边界流系;提出了印度尼西亚贯穿流的南海分支(或称南海贯穿流);不断完善了中国近海陆架环流系统,在南海环流、黑潮及其分支、台湾暖流、闽浙沿岸流、黄海冷水团环流、黄海暖流、渤海环流,以及陆架波方面均取得了深刻的认识;从大气桥和海洋桥两个方面对太平洋–印度洋–大西洋洋际相互作用进行了系统的总结;发展了浅海水团的研究方法,基本摸清了中国近海水团的分布和消长特征与机制,在大洋和极地水团分布及运动研究方面也做出了重要贡献;阐明了南海中尺度涡的宏观特征和生成机制,揭示了中尺度涡的三维结构,定量评估了其全球物质与能量输运能力;基本摸清了中国近海海洋锋的空间分布和季节变化特征,提出了地形、正压不稳定和斜压不稳定等锋面动力学机制;构建了"南海内波潜标观测网",实现了对内波生成–演变–消亡全过程机理的系统认识;发展了湍流的剪切不稳定理论,提出了海流"边缘不稳定"的概念,开发了海洋湍流模式,提出了湍流混合参数化的新方法等;在海洋内部混合机制和能量来源方面取得了新的认识,并阐述了混合对海洋深层环流、营养物质输运等过程的影响;研发了全球浪–潮–流耦合模式,推出一系列海洋与气候模式;发展了可同化主要海洋观测数据的海洋数据同化系统和用于ENSO预报的耦合同化系统;建立了达到国际水准的非地转(水槽/水池)和地转(旋转平台)物理模型实验平台;发展了ENSO预报的误差分析方法,建立了海洋和气候系统年代际变化的理论体系,揭示了中深层海洋对全球气候变化的响应;初步建成了中国近海海洋观测网;持续开展南北极调查研究;建立了台风、风暴潮、巨浪和海啸的业务化预报系统,为中国气象减灾提供保障;突破了国外的海洋技术封锁,研发了万米水深的深水水听器和海洋光学特性系列测量仪器;建立了溢油、危险化学品漂移扩散等预测模型,为伴随海洋资源开发所带来的风险事故的应急处理和预警预报提供科学支撑。文中引用的大量学术成果文献(每位第一作者优选不超过3篇)显示,经过70年的发展,中国物理海洋学研究培养了一支实力雄厚的科研队伍,这是最宝贵的成果。这支队伍必将成为中国物理海洋学研究攀登新高峰的主力军

Molecular dynamics investigation of thermal stability of Pt-Au core-shell nanoparticle

采用分子动力学方法结合嵌入原子势,对PT-Au核-壳纳米粒子的热稳定性进行了研究.计算结果表明:PT-Au纳米粒子的熔点明显高于Au纳米粒子而低于PT纳米粒子.通过计算lIndEMAnn指数发现:壳层中的Au首先熔化,然后逐渐向内部扩展,最终导致核中的PT完全熔化;熔化所经历的温度区间明显宽于单质纳米粒子,而且该熔化过程呈现典型的两阶段熔化特征;在两次熔化之间,存在着固(核)液(壳)共存的结构.In this paper,we have examined the thermal stability of Pt-Au core-shell nanoparticle by using molecular dynamics simulations with embedded-atom potential.The results show that the melting point of Pt-Au core-shell nanoparticle is significantly higher than that of pure Au one but lower than that of Pt one.By the analyses of Lindemann index,it is discovered that the melting first occurs in Au shell,then spreads into interior,finally the overall melting of Pt core appears.The temperature range of melting is much broader for Pt-Au core-shell nanoparticle than for Au and Pt nanoparticles.Moreover,Pt-Au core-shell nanoparticle exhibits a distinct two-stage melting during continuous heating,and the structure of solid(core)-liquid(shell) coexistence has been observed between two meltings.国家自然科学基金(批准号:51271156;11204252); 四川省教育厅(批准号:12ZA072)~

Melting behavior of Au-Pd eutectic nanoparticle:A molecular dynamics study

采用分子动力学方法结合嵌入原子势,对Au-Pd共晶纳米粒子的热稳定性进行了模拟研究.计算结果表明:Au-Pd纳米粒子的熔点明显高于Au单质纳米粒子而低于Pd纳米粒子.通过计算lIndEMAnn指数发现Au-Pd共晶纳米粒子中的Au原子首先熔化,然后带动Pd原子的熔化;熔化所经历的温度区间明显要宽于单质纳米粒子.In this paper,we present an investigation on thermal stability of Au-Pd eutectic nanoparticle by using molecular dynamics simulation with embedded-atom potential.The results show that the melting point of Au-Pd eutectic nanoparticle is remarkably higher than that of pure Au one but lower than that of Pd one.By the analyses of Lindemann index,it is found that Au atoms first melt,then induce the melting of Pd atoms.The temperature range of melting is broader for Au-Pd eutectic nanoparticle than that for Au and Pd nanoparticles.国家自然科学基金(批准号:10702056);福建省自然科学基金(批准号:2011J05011);四川省教育厅科研基金(批准号:12ZA072)资助的课题---

Molecular dynamics simulations of the melting of nickel nanclusters

本文采用分子动力学结合嵌入原子多体势,模拟了不同半径的Ni纳米团簇的升温熔化过程,研究团簇尺寸对熔点和表面能的影响.模拟结果表明:团簇的熔点显著低于体材料的熔点.团簇熔化的过程首先是在团簇的表面出现预熔,然后向团簇内部扩展,直到整个团簇完全熔为液态.在模拟的纳米尺度范围内,团簇的熔点与团簇尺寸基本成线性关系.团簇的表面能随着团簇尺寸的增大而减小,而且表面能均高于体材料的表面能.The melting process of nickel nanoclusters have been studied by using molecular dynamics simulations with the quantum Sutten-Chen many-body potentials to explore the size effects on the melting point and surface energy of nanoclusters.The present calculations show that the melting temperature of nickel cluster is much lower than that of bulk counterpart.The melting process of nanoclusters starts from the surface layer to the interior,and finally the nanowire becomes entirely a disordered liquid when the temperature reaches the melting point.For the nanometer region we studied,it is evidently linear relation between melting point and reciprocal of diameter.Surface energy of nanocluster decreases with the increasing diameter,and is higher than that of bulk counterpart.国家自然科学基金(10702056);; 福建省高等学校新世纪优秀人才支持计划资

基于动态规划的纯电动汽车换挡规律研究

以降低纯电动汽车在实际行驶时的能量消耗为目标，针对两挡机械自动变速器的换挡规律进行优化设计。依据太原市市区、郊区及综合行驶工况的实际需求，对汽车的驱动电机进行匹配，并基于电机效率制定出传统经济性换挡规律;通过动态规划算法求解出太原市各循环工况下的最佳挡位工作点，并提取出最优的双参数换挡规律。通过Matlab/Simulink建模和仿真，比较了不同工况下两种换挡规律的能耗差异。与传统经济性换挡规律相比，规划后的双参数换挡规律可以更好的降低汽车能耗，提升续航里程

Phase transition and coalescence behavior of fcc Fe nanoparticles: a molecular dynamics study

本文采用分子动力学模拟结合fInnIS-SInClAIr多体势研究了面心立方铁纳米粒子在加温过程中的相变与并合行为.模拟结果表明:纳米粒子在熔化之前均发生了由面心立方至体心立方的马氏体相变;大小相等的两纳米粒子在并合之前发生了相对转动;而大小不等的两纳米粒子在并合过程中并未出现转动,小纳米粒子倾向于吸附在大纳米粒子上,并随着温度的升高而熔化,最终形成更大的纳米粒子.In this paper, we present a systematic investigation on phase transition and coalescence behavior of fcc Fe nanoparticles under heating by molecular dynamics approach with Finnis-Sinclair many-body potential.The simulation results show that for fcc Fe nanoparticles, the martensitic transformation from fcc to bcc phase occurs prior to the melting.Relative rotation occurs between two like nanoparticles, but it does not happen in two nanoparticles with different sizes.A small nanoparticle prfers to adhere to a large one and is melted with temperature increasing, resulting in the final formation of a larger particle.国家自然科学基金(批准号:20833005;10702056)资助的课题---