Reverse blocking enhancement of drain field plate in Schottky-drain AlGaN/GaN high-electron mobility transistors

In this paper, we present the combination of drain field plate(FP) and Schottky drain to improve the reverse blocking capability, and investigate the reverse blocking enhancement of drain FP in Schottky-drain AlGaN/GaN high-electron mobility transistors(HEMTs). Drain FP and gate FP were employed in a two-dimensional simulation to improve the reverse blocking voltage(VRB) and the forward blocking voltage(VFB). The drain-FP length, the gate-FP length and the passivation layer thickness were optimized. VRBand VFBwere improved from-67 V and 134 V to-653 V and 868 V respectively after optimization. Simulation results suggest that the combination of drain FP and Schottky drain can enhance the reverse blocking capability significantly.     

Influences of Slope Gradient on Soil Erosion

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EFFECTIVENESS OF THE PROPELLENT CROSS-FEED TECHNOLOGY FOR LAUNCH VEHICLE

本文结合弹道优化,提出了估算和优化二级半构型运载火箭在不同发射模式和发射弹道下的近地轨道(low Earth orbit, LEO)最大运载能力的简单方法,并以长征七号为例进行了数值计算, 分析了使用推进剂交叉输送技术发射时的具体收效和最优弹道特点。数值计算表明：长征七号使用交叉输送技术发射时LEO最大运载能力能够比传统发射模式提高3 t(约20%), 同时降低发射过程中的最大轴向加速度近50%。该类型运载火箭采用推进剂交叉输送技术可以大幅提高运载能力。     

Tutorial on estimating the limit of detection using LC-MS analysis,part II: Practical aspects

In part II of this tutorial, the investigated approaches of estimating the limit of detection (LOD) are applied to experimental data from LC-MS measurements. Important practical aspects specific to LC-MS and related to LOD are reviewed. The results of different tests of estimating linearity and scedasticity are compared. LOD estimates obtained with different approaches (for both simple characterization of the analysis method and accurate interpretation of the results) are applied to the data and the obtained values are compared. As a conclusion, a decision tree is proposed for estimating LOD for analytical methods using the LC-MS technique.     

数学模拟方法研究导电剂形貌对锂离子电池高倍率放电性能的影响

制备了正极中只含有一种导电剂(KS-6或Super-P)的锂离子电池,比较了它们的倍率放电性能并对放电过程进行了模拟。以Super-P为正极导电剂的电池15C放电容量为1C容量的84.3%,以KS-6为正极导电剂的电池15C放电容量为1C容量的21.8%,前者的倍率放电性能明显优于后者。数学模拟结果显示,以KS-6为导电剂的正极的Bruggeman系数为3.1,以Super-P为导电剂的正极的Bruggeman系数为2.76,前者明显大于后者,认为这是由于KS-6的片状形貌使其容易相互平行排列造成的。大电流放电时,以KS-6为导电剂的正极中出现了电解质耗竭而导致该区域内电化学反应停止的现象,从而导致电池放电容量急剧降低。     

PVC/EVA/SBS共混体系研究

利用溶液成膜法制备了PVC/SBS薄膜 ,对其表观形态、力学性能进行了研究 ,并讨论了EVA对体系的增容作用。发现EVA在一定浓度范围内能增加PVC与SBS的相容性 ,提高断裂伸长率 .测量了溶液的相对粘度 ,得出了相反转浓度点。     

锂原子修饰B6团簇的储氢性能研究

利用密度泛函理论研究B₆和Li_mB₆ (m= 1–2)团簇的结构及其储氢性能. 结果表明, 氢分子在B₆团簇的三种可能结构中均发生解离吸附, Li原子在B₆团簇表面不发生团聚,每一个Li原子均吸附几个氢分子. 其中以两个Li原子修饰笼形B₆团簇吸附完整氢分子数最多,储氢质量分数为20.38%, 氢分子的平均吸附能为1.683 kcal/mol,表明了它在常温常压条件下作为储氢材料的可行性. 关键词： mB₆ (m=1-2)团簇')" href="#">Li_mB₆ (m=1-2)团簇 密度泛函理论(DFT) 吸附能 储氢性能     

Li4SiO4对CO2捕集性能的实验研究

以Li₂CO₃和SiO₂为原料,通过高温固相合成法合成了CO₂捕集剂Li₄SiO₄,并用X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)对所合成的材料在CO₂捕集前后的晶相变化以及微观结构进行了表征。通过热重分析仪(TGA)研究了Li₄SiO₄材料吸附CO₂的性能,并在小型热态实验台架上进行了CO₂热态捕集实验。实验结果表明,Li₄SiO₄对CO₂的捕集性能受Li₄SiO₄合成温度、CO₂的吸附温度以及气体中CO₂含量的影响,在700 ℃下制得的Li₄SiO₄具有最佳的CO₂吸附特性,最大吸附增量可达34%。Li₄SiO₄的吸附能力随着CO₂含量和吸附时间的增加而增加,当CO₂浓度分别为75%、67%、60%时,700 ℃ Li₄SiO₄对CO₂最大吸附量分别可达6.68 mmol/g、3.37 mmol/g、2.02 mmol/g (理论量8.33 mmol/g)。     

Synthesis and electrochemical performance of hole-rich Li4Ti5O12 anode material for lithium-ion secondary batteries

Hole-rich Li₄Ti₅O₁₂ composites are synthesized by spray drying using carbon nanotubes as additives in precursor solution, subsequently followed calcinated at high temperature in air. The structure, morphology, and texture of the as-prepared composites are characterized with XRD, Raman, BET and SEM techniques. The electrochemical properties of the as-prepared composites are investigated systematically by charge/discharge testing, cyclic voltammograms and AC impedance spectroscopy, respectively. In comparison with the pristine Li₄Ti₅O₁₂, the hole-rich Li₄Ti₅O₁₂ induced by carbon nanotubes exhibits superior electrochemical performance, especially at high rates. The obtained excellent electrochemical performances of should be attributed to the hole-rich structure of the materials, which offers more connection-area with the electrolyte, shorter diffusion-path length as well faster migration rate for both Li ions and electrons during the charge/discharge process.