Analysis and Simulation of S-shaped Waveguide in Silicon-on-insulator

The simulation and analysis of S-shaped waveguide bend are presented.Bend radius larger than 30 mm assures less than 0.5 dB radiation loss for a 4-μm-wide silicon-on-insulator waveguide bend with 2-μm etch depth.Intersection angle greater than 20° provides negligible crosstalk (<-30 dB) and very low insertion loss.Any reduction in bend radius and intersection angle is at the cost of the degradation of characteristics of bent waveguide and intersecting waveguide, respectively.     

Multi-antenna scheme for high capacity transmission in the digital audio broadcasting

In this paper, we apply multi-antenna scheme to DAB system for high-rate transmission. In the MIMO-DAB system with a number of transmitting and receiving antennas increases the transmission rate efficiently with low multiplication operations. For channel estimation in the MIMO-DAB system, we propose a new PRS structure and evaluate the channel estimation performance. The proposed PRS structure can estimate multi-channel information based on the semi-blind processing. The performance of proposed PRS is compared with that of conventional training sequence employing Tarokh's transmission matrix. And also we investigate the performance limitation due to the imperfect channel estimation in a MIMO-DAB receiver. It has been shown that the MIMO-DAB system with multi-antennas can achieve the high-rate transmission for multimedia broadcasting and the performance of MIMO-DAB system is impaired by imperfect channel information.     

Wavelength and repetition rate tunable optical pulse source using a chirped fiber Bragg grating and a nonlinear optical loop mirror

We experimentally demonstrate a simple and novel scheme for tunable real-repetition-rate multiplication, based on the combined use of fractional Talbot effect in a linearly tunable chirped fiber Bragg grating (FBG) and cross-phase modulation (XPM) effect in a nonlinear optical loop mirror (NOLM). By tuning the group-velocity dispersion of the chirped FBG fabricated with the S-bending method using a uniform FBG, we obtain high quality pulses at pseudorepetition rates of 20/spl sim/50 GHz from an original 8.5-ps 10-GHz soliton pulse train. We subsequently convert this pseudorate multiplication into a real-rate multiplication using XPM effect in an NOLM. A wavelength tuning is also achieved over a /spl sim/15-nm range.     

概率空间中的一个不等式

设｛Ｚ，（Ｗ）｝是定义在概率空间上的独立的随机变量序列，Ｚ（Ｗ）具有方差为期望Ｅ（Ｚｎ）＝０．本文证明了对任意算数序列｛ｂｎ｝及任意的存在充分大的整数Ｎ＞０使当Ｎ＇＞Ｎ″＞Ｎ时．有此不等式在随机级数研究中有重要作用．     

一种辐射源距离的估算方法

提出利用测量设备与辐射源相对运动速度及测量设备所接收到的辐射功率的估算测量设备到辐射源距离的一种方法。对计算精度进行了分析，通过算例对理论分析进行了检验。     

特征提取在硅内部微/纳米级体缺陷检测中的应用

提出了一种利用特征提取来对硅中微/纳米级体缺陷的激光散射图样进行分析,以获得缺陷大小信息的分析方法.给出了该方法中第一特征值和第二特征值的定义,指出通过所提出的第一特征值及第二特征值即可迅速地判断出缺陷的大小量级所在.这种分析方法具有分析速度快,在体缺陷小于1μm时分辨率高,且可使系统实现自动化等优点.     

石油企业办社会的“悖理行为”辨疑

企业办社会虽与市场经济的客观要求相悖，但石油企业大量办社会的事实仍揭示了所具备的理性面。认为国家作为不受所有者监督的代理者对石油企业的要求，石油企业的行业特性以及在传统体制下长期运作所成的定热是石油企业办社会的主要原因。     

UNIX系统发展综述

本文首先分析ＵＮＩＸ的４个发展阶段以及各阶段取得成功的原因，然后在安全性，多处理机，实时处理，微内核，国际化和流机制等几个方面说明ＵＮＩＸ在技术上的发展近况，指出要解决的问题，最后说明了它面临的新挑战。     

弹托前端结构对脱壳性能的影响

该文用四种弹托前端结构的25 mm APFSDS弹,在中间弹道靶道中进行了射击试验,利用正交多站火花阴影照相系统,得到了不同弹托脱壳过程的时序阴影照片.对照片的定量分析表明,弹托前端结构对弹托脱壳性能及弹体扰动有重要影响.