炸药近地爆炸的数值模拟及影响参数的分析

应用ANSYS/LS-DYNA有限元程序建模,在验证模型及参数选取正确可靠的基础上,研究了地面材料、炸药高度、空气域形状以及炸药当量等参数对马赫波超压的影响.结果表明:对于非近距离的爆炸,不同地面上的马赫波超压峰值相差不大,可简化为刚性地面;建模宜选择刚性壳体地面以及长方体空气域;与经验公式相比,数值模拟的马赫波超压峰值误差随着炸药当量的增大而减小,随着炸药高度的减小而增大.     

低效纳米孔晶体硅太阳电池性能研究

晶体硅太阳电池生产中,降低表面反射率能够提高太阳电池短路电流和转换效率.纳米孔硅的表面反射率极低,但报道中所实现的太阳电池输出参数(开路电压、短路电流、填充因子)都低于金字塔结构表面.采用对比法从光学性能、表面微结构和电极接触上对纳米孔硅和金字塔太阳电池进行比较分析,来研究纳米多孔硅太阳电池转换效率的抑制因素.研究表明短时间腐蚀的纳米孔硅太阳电池表面沉积氮化硅钝化膜后的平均反射率提高.长时间腐蚀的纳米孔硅表面沉积氮化硅后在短波段的反射率极低,因此平均反射率小于金字塔结构表面.但是由于纳米孔硅太阳电池的表面复合率高,而孔壁上附着的毛刺不仅会进一步增大表面复合,还会削弱表面钝化效果,因此短波段激发的光生载流子难以被太阳电池利用.所以,光利用和表面复合是抑制纳米孔硅太阳电池开路电压和短路电流的原因,而过大的串联电阻是纳米孔硅太阳电池短路电流和填充因子低的另一个原因.     

Role of Ferrel cell in daily variability of Northern Hemisphere Annular Mode

The Northern Hemisphere Annular Mode(NAM) represents the zonally symmetric planetary-scale atmospheric mass fluctuations between middle and high latitudes, whose variations have shown a large impact on other components of the climate system. Previous studies have indicated that the NAM is correlated with the Ferrel cell in their monthly or longer timescale variability.However, there have been few studies investigating their connections at daily timescale, though daily variability of NAM has been suggested to be an important component and has significant implication for weather forecast. The results from this study demonstrate that variability of the Ferrel cell leads that of the NAM by about 1–2 days. This statistically identified temporal phase difference between NAM and Ferrel cell variability can be elucidated by meridional mass redistribution. Intensified(weakened)Ferrel cell causes anomalously smaller(larger) poleward mass transport from the middle to the high latitudes,resulting in an increase(a decrease) in mass in the middle latitudes and a decrease(an increase) in the high latitudes.As a consequence, anomalously higher(lower) poleward pressure gradient forms and the NAM subsequently shifts to a positive(negative) phase at a time lag of 1–2 days. The findings here would augment the existing knowledge for better understanding the connection between the Ferrel Cell and the NAM, and may provide skillful information for improving NAM as well as daily scale weather prediction.     

Antilocalization sensing of interactions between two-dimensional electrons and surface species

We apply antilocalization measurements to experimentally study the interactions and exchange between InAs surface accumulation electrons and local magnetic moments of the rare earth ions Sm3?,Gd3?,Ho3?,and Dy3?,of the transition metal ions Ni2?,Co2?,and Fe3?,and of Fe3O4nanoparticles and Fe3?-phthalocyanine deposited on the surface.The influence of the deposited species on the surface electrons is observed through the changes in the spin–orbit scattering and magnetic spin-flip scattering rates,which carry information about magnetic interactions.Experiments indicate a temperature-dependent magnetic spin-flip scattering for Ho3?,Dy3?,Ni2?,and Co2?.Concerning the spin–orbit scattering rate,we observe an increase,except for the cases of Ni2?,Fe3?,Fe3O4nanoparticles and Fe3?-phthalocyanine.We also observe an increase in SO scattering in another system where we study the interactions of Au nanoparticles and ferromagnetic Co0.6Fe0.4nanopillars and an In0.53Ga0.47As quantum well.Experimental results are analyzed and compared to theoretical models.Our method provides a controlled way to probe the quantum properties of two-dimensional electron systems,either on the surface of InAs or in a quantum well.     

数值模拟单个金纳米棒的吸收和散射特性

利用时域有限差分的方法,数值模拟了单个金纳米棒的吸收、散射和消光特性,比较了在相同长径比,不同长轴金纳米棒的吸收和散射效率。数值计算结果表明:金纳米棒的散射效率会随着金纳米棒的几何尺寸的增大而逐渐增强,并且其散射谱的半高宽也随之变宽;与之相反的是,金纳米棒对入射光的吸收效率随金纳米棒体积的增大却呈现出先增加后减小的变化规律。数值模拟结果将为金纳米棒在太阳能电池光俘获方面的应用提供有益的理论参考。     

Investigation on the electrochemical activation process of Li1.20Ni 0.32Co0.004Mn0.476O2

The lithium-rich layered oxides are one of the most attractive cathode materials for lithium-ion batteries.Here,two types of Li1.20Ni0.32Co0.004Mn0.476O2 were synthesized using Li2CO3 and LiOH as lithium sources.An electrochemical activation process occurs in Li1.2Ni0.32Co0.004Mn0.476O2 prepared from Li2CO3(LLO-1),while no obvious activation in Li1.2Ni0.32Co0.004Mn0.476O2 prepared from LiOH(LLO-2) is observed.Via advanced scanning transmission electron microscopy(STEM),we found that Li2MnO3-like structure is rich in the surface region of LLO-2.The study provides a direct explanation for the electrochemical activation of lithium-rich materials.The sample with more LiMO2-like phase at the surface region shows a better cycling performance.It is likely that more LiMO2-like phase at the surface region could stabilize the interface and improve the cycling performance of the Li-rich cathode materials.     

广义KdV方程的数值解法

采用一种线性隐格式来解广义非线性KdV方程,这种方法是无条件稳定的.数值实验描述了单个线性孤立子波运动的情形以及两个孤立子波交互的情形,结果表明,这种方法有很好的稳定性和精度.     

Background current affects the internal wave structure of the northern South China Sea

The internal wave modal equations are solved with the consideration of background currents. Analytical and numerical solutions of some specific examples, including observations in the northern South China Sea （SCS）, are obtained to investigate the effect of back- ground current on internal wave vertical structure. The effects of current shear and curvature on internal wave vertical structure are eval- uated separately. It is found that the phase speed and wave structure are modified by background currents, the current shear has little effect on wave structure, whilst the current curvature could have a strong impact on the wave structure. The extent of the effect by the current curvature on the wave structure depends on the magnitudes of current curvature, relative wave speed, and buoyancy frequency, sometimes the effect by the current curvature may even cause the wave to attenuate severely with depth. A new method to obtain the real eigenfunction with depth in the case that the waves become evanescent is also put forward. It is shown that the residual tidal current in the northern SCS is strong enough to cause the wave to attenuate severely at the uooer laver.     

穿墙生命探测回波信号分析

穿墙生命探测（TWS）是研究障碍物后有无生命现象的一种探测技术。该文主要研究基于连续渡体制的TWS探测器回波信号。推导了这种探测器的回波信号表达式,根据生命体征特点,采用简谐振动模型,利用贝塞尔函数对回波信号展开分析并进行了实验验证。实测信号和仿真信号的比较结果表明二者吻合良好。详细分析了穿墙前后TWS探测器回波变化特征,指出穿墙后信号处理的重点是对呼吸信号的检测。     

试论Tesla标量波

Nikola Tesla是现代科技文明的创始人之一;他的标量波不但可用于能量和信息传输,而且非常有趣。如所周知无线电波和光波都是横波,但Tesla标量波更像电磁势在传播方向上的扩张和收缩。在电磁理论研究中,实验均证明了矢势和标势的物理实在性,这是对Tesla标量波理念的支持。我们已知像Aharonov-Bohm效应和量子纠缠态这类非力效应的情况,Tesla标量波也是这种效应。本文提出了Tesla波可能有超光速性的原因:首先是Aharonov-Bohm效应具有量子力学非局域性;其次是类消失态的近场效应;因此Tesla纵波以超光速传播是可能的。但还应做更多的实验。