一种高速浮点加法器的设计实现

浮点加法器是协处理器的核心运算部件，是实现浮点指令各种运算的基础，其设计优化是提高浮点运算速度和精度的关键途径。文章从浮点加法器算法和电路实现的角度给出设计方法，并且提出动态与静态结合设计进位链的方案以及前导O预测面积与速度的折衷方法。动态与静态结合设计进位链的方法有效地降低了功耗，提高了速度，改善了性能。目前已经嵌入协处理器的设计中，并且流片测试成功。     

谐振式力传感器对其晶振频率稳定度的要求

为了寻找石英晶振频率稳定度对传感器影响的判据,根据石英谐振式力传感器的灵敏度阈值和量程与晶体的相关常数及结构参数间的关系,导出了反映谐振式力传感器研究水平的指标参数与晶体结构参数及晶振频率稳定度之间的关系式,为传感器的研究提供了依据。例如,欲制作量程阈值比达到105量级的传感器,所用晶振的频率稳定度必须优于108。     

基于HDLC协议的高速SDH传输系统板间通信的设计与实现

针对SDH传输系统板间通信传统设计方法的不足,介绍一种采用HDLC协议进行设计的新方法,并在MPC852T型嵌入式微处理器上得以实现.严格的验证证明其在可靠性和传输速率方面获得了很好的性能.     

用SY87721实现城域网波分复用系统的多业务接入

为了使城域网的DWDM（密集波分复用）系统可以接入多种信号速率和格式，以满足用户的要求，首先介绍了一种波长转换板的设计方法，使用SY87721自适应提取28Mbit／s～2.7Gbit/s之间任意速率信号的时钟，其次介绍了SY87721提取时钟的工作原理、与单片机和CPLD（复杂可编程逻辑器件）的接口方式、对寄存器的配置和读出方式。最后介绍了使用参考时钟测量接入信号频率的方法，这会在系统维护时带来较大的方便。     

线性规划的符号跟踪算法

分析了只含一个约束条件的线性规划最优基变量的特征，将其运用到搜寻含m个约束条件的线性规划的最优基变量，从而提出了线性规划的符号跟踪算法，为线性规划求解提供了新途径。     

Time-Resolved Femtosecond Degenerate Four-Wave Mixing in LiNbO3：Fe,Mg Crystal

Forward degenerate four-wave mixing （DFWM） processes are investigated with a femtosecond pulsed laser in lithium niobate crystal doubly-doped with magnesium and iron （LiNbO3：Fe, Mg）. The pulse energy dependence reveals a pure third-order nonlinear response, and the third-order nonlinear susceptibility x^（3） in the material is evaluated to be 4.96 × 10^-13 esu. The time-resolved DFWM process shows a response time of x^（3） shorter than 100fs, which is due to the nonresonant electronic nonlinearities. Our results indicate that LiNbO3 crystals have potentials for ultrafast real-time optical processing systems, which require a large and fast x^（3） optical nonlinearity.     

用地面阵列寻找TeV能区γ点源的方法探讨

文中探讨搜寻TeV能区γ点源的方法.讨论利用student变量t判断来自源区及背景区宇宙线事例的统计差别,并由Bayes定理与MonteCarlo模拟相结合计算源区各能段的信号数,推算蟹状星云在TeV能区的γ射线微分能谱     

岩盐型ZnO纳米微粒的光电子发射结构

报道了岩盐型氧化锌纳米微粒的X射线光电子发射结构,发现其中3d电子的强烈成键作用,还存在着3d-4sp杂化和离域电子弛豫态的贡献,表现出与纤锌矿型明显的差异. 关键词：     

A Two-Dimensional Photonic Crystal Slab Mirror with Silicon on Insulator for Wavelength 1.3μm

A concrete two-dimensional photonic crystal slab with triangular lattice used as a mirror for the light at wavelength 1.3μm with a silicon-on-insulator （SOI） substrate is designed by the three-dimensional plane wave expansion method. For TE-like modes, the bandgap in the Г-K direction is from 1087nm to 1559nm. The central wavelength in the bandgap is about 1.3μm, hence the incident light at wavelength 1.3μm will be strongly reflected. Experimentally, such a photonic crystal slab is fabricated on an SOI substrate by the combination of EBL and ICP etching. The measurement of its transmission characteristics shows the bandgap edge in a longer wavelength is about 1540 nm. The little discrepancy between the experimental data and the theoretical values is mainly due to the size discrepancy of the fabricated air holes.     

Multiple-State Storage Capability of Stacked Chalcogenide Films （Si16Sb33Te51/Si4Sb45Te51/Si11Sb39Te50） for Phase Change Memory

The multiple-state storage capability of phase change memory （PCM） is confirmed by using stacked chalcogenide films as the storage medium. The current-voltage characteristics and the resistance-current characteristics of the PCM clearly indicate that four states can be stored in this stacked film structure. Qualitative analysis indicates that the multiple-state storage capability of this stacked film structure is due to successive crystallizations in different Si-Sb-Te layers triggered by different amplitude currents.