一种基于调制模式识别的载波同步方案

介绍了一种多模式锁相环的工作原理,结合多模式锁相环提出了一种基于调制模式识别的载波恢复的方案,它同时也可以作为在存在频率和相位偏移的情况下,调制模式识别的一种措施。并分析了该载波同步方案的各项性能,最后通过计算机仿真验证了该方案的正确性。     

自适应判决门限延时相关分组检测算法

提出了结合双滑动窗口方法和延时相关分组检测的优化算法。该算法利用双滑动窗口算法在峰值点可以用于估计接收信号信噪比的特点,通过对接收信号信噪比的简单估计来确定最佳判决门限,动态跟踪信道变化,使分组同步更加准确。新算法在IEEE802.11a系统中进行了仿真,结果表明新算法的性能比原延时相关分组检测算法有了很大提高。     

Creep behavior of eutectic Sn-Cu lead-free solder alloy

Tensile creep behavior of precipitation-strengthened, tin-based eutectic Sn-0.7Cu alloy was investigated at three temperatures ranging from 303–393 K. The steady-state creep rates cover six orders of magnitude (10⁻³−10⁻⁸ s⁻¹) under the stress range of σ/E=10⁻⁴−10⁻³. The initial microstructure reveals that the intermetallic compound Cu₆Sn₅ is finely dispersed in the matrix of β-Sn. By incorporating a threshold stress, σ _th, into the analysis, the creep data of eutectic Sn-Cu at all temperatures can be fitted by a single straight line with a slope of 7 after normalizing the steady-state creep rate and the effective stress, indicating that the creep rates are controlled by the dislocation-pipe diffusion in the tin matrix. So the steady-state creep rate, , can be expressed as exp , where Q_c is the activation energy for creep, G is the temperature-dependent shear modulus, b is the Burgers vector, R is the universal gas constant, T is the temperature, σ is the applied stress, A is a material-dependent constant, and , in which σ _OB is the Orowan bowing stress, and k_R is the relaxation factor. An erratum to this article is available at .     

I-WAP: an intelligent WAP site management system

The popularity regarding wireless communications is such that more and more WAP sites have been developed with wireless markup language (WML). Meanwhile, to translate hypertext markup language (HTML) pages into proper WML ones becomes imperative since it is difficult for WAP users to read most contents designed for PC users via their mobile phone screens. However, for those sites that have been maintained with hypertext markup language (HTML), considerable time and manpower costs will be incurred to rebuild them with WML. In this paper, we propose an intelligent WAP site management system to cope with these problems. With the help of the intelligent management system, the original contents of HTML Web sites can be automatically translated to proper WAP content in an efficient way. As a consequence, the costs associated with maintaining WAP sites could be significantly reduced. The management system also allows the system manager to define the relevance of numerals and keywords for removing unimportant or meaningless contents. The original contents will be reduced and reorganized to fit the size of mobile phone screens, thus reducing the communication cost and enhancing readability. Numerical results gained through various experiments have evinced the effective performance of the WAP management system.     

RF CMOS technology for MMIC

This paper presents a high performance RF CMOS technology with a complete portfolio of RF and base band components for single-chip systems. Using an optimized 0.13 μm CMOS topology, f_T of 86 GHz and f_max of 73 GHz are obtained, in addition to a NF_min of 1.5 dB without ground-shielded signal pad. The high-Q accumulation-mode and diode varactors are optimized to perform a high tuning range of 47% and 25%, respectively. Inductors with a quality factor of 18 at 1.7 nH are obtained using copper interconnect, while capacitors with high unit capacitance and quality factor are fabricated with metal-insulator-metal structures. Finally, a deep n-well isolation is adopted to suppress the interblock coupling noise penetrating through substrate by 40 and 25 dB at 0.1 and 2.4 GHz, respectively. These results clearly demonstrate that CMOS technology can provide a complete solution for single-chip wireless systems.     

STUDY ON GIS BASED PREDICTION SYSTEM FOR RADIO WAVE PROPAGATION IN UBAN REGION

In this letter, an integrated application of the prediction for radio wave propagation with the Geographic Information System (GIS) is presented and a real prediction system based on GIS is implemented.     

新的正向栅控二极管技术分离热载流子应力诱生SOI NMOSFET界面陷阱和界面电荷的研究

报道了用新的正向栅控二极管技术分离热载流子应力诱生的SOI-MOSFET界面陷阱和界面电荷的理论和实验研究.理论分析表明:由于正向栅控二极管界面态R-G电流峰的特征,该峰的幅度正比于热载流子应力诱生的界面陷阱的大小,而该峰的位置的移动正比于热载流子应力诱生的界面电荷密度. 实验结果表明:前沟道的热载流子应力在前栅界面不仅诱生相当数量的界面陷阱,同样产生出很大的界面电荷.对于逐渐上升的累积应力时间,抽取出来的诱生界面陷阱和界面电荷密度呈相近似的幂指数方式增加,指数分别为为0.7 和0.85.     

广义克尔介质对双模压缩真空场与原子相互作用系统原子量子特性的影响

运用全量子理论,研究了存在广义克尔介质时,双模压缩真空场与二能级原子相互作用系统中原子布居数的时间演化和原子的偶极压缩效应,着重讨论了广义克尔介质与双模压缩真空场作用的耦合强度x,失谐量Ω以及广义克尔介质的非线性阶数m对原子行为的影响。     

一种与矩阵理论相结合的密码体制

给出了一种基于实对称矩阵理论的密码体制,包括密钥的设定、加密方法、解密方法和实例,并对其进行了分析。     

使用自举积分电路的精密电流源设计

如图1所示的普通电流源的精确度不低于1%,而且对温度不太敏感(温度系数低于5×10-5/℃).该电路有较高的输出阻抗和较宽的电压允许范围(4.3～34V).它采用电压参考集成电路IC1及电阻R1来产生一个稳定的电流源,并符合表达式ISOURCE=VREF/R1+IC1的对地电流.