石墨烷纳米条带阵列中的近自由电子态

Nearly free electron (NFE) state has been widely studied in low dimensional systems. Based on first-principles calculations, we identify two types of NFE states in graphane nanoribbon superlattice, similar to those of graphene nanoribbons and boron nitride nanoribbons. Effect of electron doping on the NFE states in graphane nanoribbon superlattice has been studied, and it is possible to open a vacuum transport channel via electron doping.     

Top contact organic field effect transistors fabricated using a photolithographic process

This paper proposes an effective method of fabricating top contact organic field effect transistors by using a pho-tolithographic process.The semiconductor layer is protected by a passivation layer.Through photolithographic and etching processes,parts of the passivation layer are etched off to form source/drain electrode patterns.Combined with conventional evaporation and lift-off techniques,organic field effect transistors with a top contact are fabricated suc-cessfully,whose properties are comparable to those prepared with the shadow mask method and one order of magnitude higher than the bottom contact devices fabricated by using a photolithographic process.     

大晶粒UO2燃料裂变气体释放行为相场模拟研究

为预测大晶粒UO₂燃料中裂变气体的释放行为,从而为事故容错燃料的发展提供支持,本文采用相场模型,对裂变气体在UO₂多晶微观结构中的释放行为进行了模拟.该模型采用一组耦合的Cahn-Hilliard方程与Allen-Cahn方程,用守恒场变量表示裂变气体与空位的分布,以及用序参量区分气泡相与基质相.该模型重点考察了不同晶粒尺寸、不同温度条件与扩散系数对裂变气体释放行为产生的影响,展现了气泡的形核、生长、融合等行为,得到了一定程度燃耗深度下燃料的孔隙度、晶界处气泡覆盖率、气泡平均半径等模拟结果.结果表明,温度与扩散系数对孔隙度、晶界处气泡覆盖率的影响较为显著,在扩散系数较大时,晶粒尺寸也会对裂变气体释放行为产生较大影响,扩散系数较小时,晶粒尺寸的影响则不明显.此外,通过该模型得出的高燃耗深度下裂变气体气泡分布状况与实验结果也较为符合,该模型能较好地预测大晶粒UO₂裂变气体释放行为.     

异质结及其技术在新型硅基太阳能电池中的应用

文章综述了异质结及其技术在新型硅基太阳能电池中的应用.从太阳能电池特性角度,点评了其在晶体硅、非晶硅薄膜太阳能电池及新结构太阳能电池应用中的研究热点和研究现状.在此基础上,讨论了其在不断与晶体硅、薄膜硅太阳能电池融合中的发展动态.     

微波消解-火焰原子吸收光谱法测定冬虫夏草中的微量元素

采用微波消解处理冬虫夏草,使用火焰原子吸收光谱法测定其6种微量元素的含量。冬虫夏草中铁、铜、锌、锰、镁、钙的含量分别为874.68,7.82,96.22,53.47,1743.91,196.80μg·g^-1。该方法加标回收率为在99.05%—102.32%之间,方法简单、快速、灵敏、准确,可为冬虫夏草的食品开发,中药的基础研究提供依据。     

LFP/C掺杂型PVDF-HFP隔膜及其电化学性能研究

本论文向聚偏氟乙烯-六氟丙烯中添加磷酸铁锂纳米颗粒制备得到PVDF-HFP/LFP复合隔膜材料。通过这种掺杂改性,提升了隔膜的吸液率,湿润性,热稳定性,以此提升电池的放电比容量和循环性能。电池正极使用经过碳包覆的磷酸铁锂材料,负极使用金属锂片,通过制备的不同隔膜组装电池探究磷酸铁锂纳米颗粒的添加对PVDF-HFP隔膜性能的影响,并研究了不同比例的磷酸铁锂纳米颗粒对聚合物隔膜的影响。     

Two-Photon Interference Constructed by Two Hong–Ou–Mandel Effects in One Mach-Zehnder Interferometer

We present a two-photon interference experiment in a modified Mach-Zehnder(MZ) interferometer in which two Hong–Ou–Mandel effects occur in tandem and construct superposed two-photon states. The signal photons pass both the arms of the MZ interferometer while the idler photons pass one arm only. Interestingly, the probability of the idler photons emerging from any output port still shows a sine oscillation with the two-photon phase difference and it can be characterized only by the indistinguishability of the two-photon amplitudes. We also observe a two-photon interference pattern with a period being equal to the wavelength of the parametric photons instead of the two-photon photonic de Broglie wavelength due to the presence of two-photon phase difference, in particular, with complementary probabilities of finding the two-photon pairs in two output ports. The abundant observations can facilitate a more comprehensive understanding of the two-photon interference.     

陆用高精度激光惯导装备使用维护问题研究

目前国内装备应用单位对陆用高精度激光惯导装备的使用维护保养不当或不规范对惯性装备性能的影响尚无准确的理论分析,为此,以某型陆用高精度激光陀螺定位定向系统为研究对象,结合国内惯性传感器技术水平现状,详细分析了陆用高精度激光惯导装备对维护保养的需求以及规范维护保养作业的重要性。该型产品通过定期通电和系统定标维护,故障产品性能恢复,维护保养前后的水平定位精度典型实测数据分别为8.35 m(CEP)和2.9 m(CEP),以期为国内同类装备的设计、生产以及部队使用提供参考和理论支撑。     

预应力CFRP板平板锚具承载力评估理论与试验研究

为揭示CFRP板平板锚具的锚固机理, 建立了该锚具的承载力理论模型, 并利用该模型预测CFRP板平板锚具的临界锚固长度. 通过试验获得了模型所需的锚固界面剪应力与压应力的关系式. 该模型研究了锚固区界面剪应力的纵向折减及横向压应力分布的不均匀性, 并通过试验测得了界面剪应力的纵向折减系数. 利用上述模型就平板锚具设计参数对锚固性能的影响进行了分析. 结果表明, 界面剪应力折减率随着锚固长度的增大而增大, 横向压应力分布的不均匀性随着锚固宽度的增大而增大, 增大界面压应力和夹板厚度能有效提高横向压应力分布的均匀度; 临界锚固长度随夹板厚度的增大而减小, 且当夹板达到合适厚度后继续增大, 对临界锚固长度的影响逐渐变小; 随着界面压应力的增大, 界面剪应力增大, 临界锚固长度减小; 对于工程常用CFRP板尺寸100mm×2.0mm, 当界面压应力取100MPa, 平板锚具夹板厚度取32mm时, 所需的临界锚固长度为296mm, 对应的锚具设计承载力为480kN, 理论上能使CFRP板抗拉强度获充分发挥.     

Annealing temperature influence on the degree of inhomogeneity of the Schottky barrier in Ti/4H–SiC contacts

Tung＇s model was used to analyze anomalies observed in Ti/Si C Schottky contacts. The degree of the inhomogeneous Schottky barrier after annealing at different temperatures is characterized by the ‘T0anomaly＇ and the difference（△Φ）between the uniformly high barrier height（Φ0B） and the effective barrier height（Φeff B）. Those two parameters of Ti Schottky contacts on 4H–Si C were deduced from I–V measurements in the temperature range of 298 K–503 K. The increase in Schottky barrier（SB） height（ΦB） and decrease in the ideality factor（n） with an increase measurement temperature indicate the presence of an inhomogeneous SB. The degree of inhomogeneity of the Schottky barrier depends on the annealing temperature, and it is at its lowest for 500-°C thermal treatment. The degree of inhomogeneity of the SB could reveal effects of thermal treatments on Schottky contacts in other aspects.