空位缺陷对单晶硅薄膜热导率影响的分子动力学模拟研究

采用非平衡分子动力学(NEMD)方法及Tersoff势能函数模拟了微尺度下空位结构缺陷对单晶硅薄膜热导率的影响。结果表明,硅薄膜的热导率随空位浓度的增加而明显减小。当温度为300~700K时,随着温度的升高,空位浓度对热导率的影响以及同一空位浓度下温度对热导率的影响都逐渐减弱。     

对骨架公路网指标评价方法的探讨

根据总量控制法的基本原理,结合贵州省的具体情况,通过公路网评价指标体系、定量分析模型及专家意见,对贵州省现有骨架公路网进行了模糊评判,揭示了现状骨架公路网的主要矛盾和问题.     

应变影响下单晶Ge薄膜热导率分析

利用非平衡态分子动力学模拟方法研究了应变对Ge薄膜热导率的影响。结果表明系统应变对单晶Ge薄膜热导率产生明显影响,热导率随着拉伸应变的增大而减小,随着压缩应变的增大而增大,得出声子速率降低以及薄膜表面重构是产生该模拟结果的内在原因。同时,采用修正的Callaway模型对NEMD结果进行理论验证,两种方法得到的结果吻合得较好。理论结果表明应变弛豫时间对Ge单晶薄膜的热导率产生了重要影响。     

Effects of vacancy structural defects on the thermal conductivity of silicon thin films

Vacancy structural defect effects on the lattice thermal conductivity of silicon thin films have been investigated with non-equilibrium molecular dynamics simulation.The lattice thermal conductivities decrease with increasing vacancy concentration at all temperatures from 300 to 700 K.Vacancy defects decrease the sample thermal conductivity,and the temperature dependence of thermal conductivity becomes less significant as the temperature increases.The molecular dynamics result is in good agreement with the theoretical analysis values obtained based on the Boltzmann equation.In addition,theoretical analysis indicates that the reduction in the lattice thermal conductivity with vacancy defects can be explained by the enhanced point-defect scattering due to lattice strain.     

空位缺陷对Si薄膜热导率的影响

利用非平衡分子动力学方法研究了空位结构缺陷对Si薄膜热导率的影响。当温度在300K-700K之间变化时,热导率随着空位浓度的增加而降低,并且随着温度的升高空位浓度对热导率的影响以及同一空位浓度下温度对热导率的影响都在逐渐减弱。本文还利用Boltzmann输运理论对MD模拟进行验证,结果基本与其一致。同时理论方法还表明,空位缺陷对薄膜热导率的巨大影响归因于晶格应力的存在使点缺陷也发生散射作用的结果。     

Effects of Strains on Thermal Conductivity of Si/Ge Superlattices

The effect of strains on the thermal conductivity of Si/Ge superlattices was investigated by nonequilibrium molecular dynamics (NEMD) simulation. The thermal conductivities experienced a near linear drop with increasing tensile and compressive strains. It was explained by the fact that the decrease of the phonons velocities and a mass of structural defects generated under strains. Meanwhile, a theoretical calculation based on Modified-Callaway model was performed and it was found that the theoretical results were in good agreement with the molecular dynamics results.     

单晶Ge纳米薄膜面向热导率的分子动力学模拟

利用非平衡分子动力学模拟方法研究了单晶Ge薄膜的厚度以及温度对其面向热导率的影响规律。针对单晶Ge薄膜的结构特点和导热机制,采用Stillinger-Weber势能模型描述Ge粒子间的相互作用,并且建立面向稳态热传导模型。模拟结果显示,单晶Ge薄膜面向热导率具有明显尺寸效应,随薄膜厚度的增加而增大,随温度的升高而减小。与法向热导率的模拟结果进行比较,证明单晶Ge薄膜热导率具有各向异性的特点。     

为企业持续发展招“凤”引“蝶”

需要招引什么样的凤凰、就要构筑什么样的巢穴,要营造吸引人才、留住人才的环境和条件。     

3D打印技术在食品中的应用

3D食品打印作为一种新兴的"增材制造"技术,具有方便、快捷、精度高等优点,满足了人们对个性化、功能性食品的要求,现已广泛应用于食品行业。本文综述了3D食品打印技术的原理、发展历史与现状,重点对食品原料的特性、打印食品的种类及影响打印的因素进行分析,并对3D食品打印技术的发展做出了展望。