Valence band density of states of small cobalt particles on Si(111) substrate

Small Co particles were prepared by sputter etching of a 4–5 nm thick island-like Co film deposited on Si(111) substrate. The density of states (DOS) of the valence band was measured by means of ultraviolet photoemission (UPS) during the sputter etching to monitor the formation of small Co particles. It was found that at a given thickness of the Co island the Fermi level was shifted by 1.8-1.9 eV toward higher binding energy and theDOS decreased or no states were detectable at the Fermi level. This effect was explained by the formation of small Co particles with electronic structure which is significantly different from that of the bulk Co.     

单用户操作系统MS—DOS6.21

该文介绍了ＭＳ－ＤＯＳ６．２１版从用户角度出发在ＭＳ－ＤＯＳ６．２基础上所作的改进，包括一些新增加或增强了命令、实用程序及为特殊用户提供的服务软件包ＡｃｃｅｓｓＤｏｓ，另外还对网络用户的ＤＯＳ升级作了简要说明。     

蜜罐技术在防御分布式拒绝服务攻击中的应用

Internet的迅速发展使网络信息安全问题变得日益突出,在防御DDOS攻击方面一直没有较理想的方法。这里分析了蜜罐技术,并首次给出了它在防御分布式拒绝攻击中的应用。     

Reconfigurable Optical Add‐Drop Multiplexer Using a Polymer Integrated Photonic Lightwave Circuit

We have developed a fully functional reconfigurable optical add‐drop multiplexer (ROADM) switch module using a polymer integrated photonic lightwave circuit technology. The polymer variable optical attenuator (VOA) array and digital optical switch array are integrated into one polymer PLC chip and packaged to form a 10‐channel VOA integrated optical switch module. Four of these optical switch modules are used in the ROADM switch module to execute 40‐channel switching and power equalization. As a wavelength division multiplexer (WDM) filter device, two C‐band 40‐channel athermal arrayed waveguide grating WDMs are used in the ROADM module. Optical power monitoring of each channel is carried out using a 5% tap PD. A controller and firmware having the functions of a 40‐channel switch and VOA control, optical power monitoring, as well as TEC temperature control, and data communication interfaces are also developed in this study.     

Prediction of semiconducting behavior in minority spin of Co2CrZ（Z=Ga,Ge,As）:LSDA

正Volume optimization was performed to obtain the theoretical lattice constants by using the generalized gradient approximation(GGA).The electronic and magnetic properties of Heusler alloys Co_2CrZ(Z = Ga,Ge, As) were investigated by using local spin density approximation(LSDA).Amongst the systems under investigation, Co_2CrGe and Co_2CrGa give 100%spin polarization at the Fermi level(E_f)- Co_2CrGe and Co_2CrGa are the most stable half-metallic ferromagnets(HMFs);their E_F lie exactly at the gap of 0.24 eV and 0.38 eV,respectively,in the spin-down channel.Even though Co_2CrAs gives a distinct and bigger gap as compared to Co_2CrGa and Co_2CrGe, its E_F is not located at the middle of the gap in the spin-down channel.We have also found that the total magnetic moments increase as the Z goes from Ga to As.The calculated density of states and band structures show the HMF character for Co_2CrGe and Co_2CrGa.     

互联网防御DOS/DDOS攻击策略研究

主要介绍DOS/DDOS攻击的原理与种类,并着重介绍防御DOS/DDOS攻击的应对策略,并结合专业防御系统对构建专业防御体系进行了探讨。     

CdTe和HgTe能带结构的第一性原理计算

利用基于第一性原理的FLAPW方法计算了CdTe和HgTe的能带结构和态密度．引进并利用快速搜索法计算了体系平衡时的晶格常数,相对于传统方法,更快速地得到了准确的平衡态的晶格常数．本文在计算得到与实验结果符合很好的能带结构和态密度的同时,对比分析了基于LSDA和GGA计算所得的结果．     

Electronic structures of high-k transition metal silicates: first-principles calculations

The energy band gaps and total density of states of different transitional metal (Sc, Zr) silicates have been studied using density functional theory and local density approximation. The problem of a decreasing band gap in Zr silicate predicts the band offset reduction from the introduction of 4d state below the conduction band edge. While, in case of Sc silicate, there is no such decrease in the band gap and it becomes more suitable for the device performances.     

LiNbO3 1×2非对称电极Y分叉数字光开关的研究

文章提出一种关于非对称电极低串扰数字光开关的新型设计方案,在Y分叉后端引入S弯曲波导,通过在Y分叉处的非对称电极和弯曲波导的弯曲电极处施加一定的同步电压,实现了比没有S弯曲的开关更低的串扰.此种设计采用有限差分光束传播方法(FDBPM)来分析,模拟结果显示,在光波长为1.55 μm时,开关电压8 V,串扰＜-25 dB.     

Internet垃圾邮件过滤技术研究

通过分析垃圾邮件的来源，提出了过滤垃圾邮件的方法，建立了相应的过滤规则，并通过实验证明了该规则的有效性。