Miniature InGaAsP/InP phase modulator for integrated opto-electronics

Miniature, etching ridge InGaAsP/InP Phase Modulator with highly efficient phase shifting efficiency of 60°/V.mm and 43°/V.mm for TE and TM modes, respectively, and 3 dB bandwidth of 650 MHz at 1.52 μm are reported. It is well suited for integrated opto-electronics. Some functions depending on bandwidth of the devices are discussed.     

激光诱导光栅技术测量磁性液体的热扩散系数

在室温和常压下采用激光诱导光栅技术实验测量不同体积分数的磁性液体的热扩散系数,体积分数分别为5%,6%,7%,8%,9%和10%。由于在磁性液体薄片上的升温非常小以及毫秒级的测量时间,自由对流所产生的影响可以忽略不计。用激光诱导光栅技术测的数据与已有文献中的实验数据比较吻合,从而说明该技术在磁性液体的热扩散测量上是可行的。     

钯与希夫碱类配合物的合成与表征

合成了把(I)与五个希夫碱的七个新配合物:(L1-H)护d, 相似文献   

金(l)与铂(IV)和N-氧化毗咤-2一甲醛半卡巴腺配盐的合成及其晶体结构

本文首次报道N-氧化毗咤-2一甲醛希夫碱配体与贵金属Au ( I)和Pt(N)的配盐[( C,HsN,Ox ) zH] [AuCI, ] ( In)和〔C,HgN,Oz)xH]z[PtCle] " 6Ha0)(2)的合成，并使用元素分析、红外、紫外、荧光光谱、摩尔电导的手段进行结构表征;并报道配盐1的晶体结构，配盐1的晶体学数据:C2/c,a=19. 223(2)人,b=7.510(1)人,c=16.414(5)人，夕=115.73(1)0,R=0. 037.晶休结构研究表明:配盐是由阳、阴离子缔合而成的中心对称的配盐分子。     

江西省社会发展评价指标体系的建构及对各地市的评价

本文介绍了由本省省情构建的一套江西省社会发展评价指标体系,并用系统工程和计算机技术对全省11地市1988至1990年三年间的社会发展进行综合评述。     

用于单载波频域均衡水声通信的可分近似稀疏信道估计

针对单载波频域均衡水声通信中信道估计易受噪声干扰的问题,提出了一种低复杂度的信道估计方法。考虑水声信道的时域稀疏特性,导出频域输入、输出信号与信道冲激响应的关系式,并引入稀疏正则项,构造稀疏信道估计的目标函数。然后利用可分近似对目标函数进行迭代优化,再经过稀疏化与去偏处理,得到信道传递函数的最终估计。最后,利用数值仿真和海试数据对所提出方法的性能和运算效率进行评估。较之传统信道估计方法,所提出的方法在估计精度和计算复杂度方面具有一定的优势。     

Structure of zirconium dioxide based porous glasses

This study is devoted to investigation of the micro- and mesostructure (including fractal properties) of porous zirconia glasses synthesized by precipitation from zirconium n-propoxide solutions in the presence of different hydrolyzing-agent (H₂O) quantities at different temperatures. Analysis of small-angle neutron, ultra-small-angle neutron and X-ray scattering, scanning electron microscopy allows concluding that the synthesized glasses are complex systems with a three-level hierarchical fractal structure. It is revealed that both the temperature of synthesis and the H₂O concentration in the initial solution significantly affect the structural characteristics of the glasses.     

A new multichannel time reversal focusing method for circumferential Lamb waves and its applications for defect detection in thick-walled pipe with large-diameter

This paper proposes a new multichannel time reversal focusing (MTRF) method for circumferential Lamb waves which is based on modified time reversal algorithm and applies this method for detecting different kinds of defects in thick-walled pipe with large-diameter. The principle of time reversal of circumferential Lamb waves in pipe is presented along with the influence from multiple guided wave modes and propagation paths. Experimental study is carried out in a thick-walled and large-diameter pipe with three artificial defects, namely two axial notches on its inner and outer surface respectively, and a corrosion-like defect on its outer surface. By using the proposed MTRF method, the multichannel signals focus at the defects, leading to the amplitude improvement of the defect scattered signal. Besides, another energy focus arises in the direct signal due to the partial compensation of dispersion and multimode of circumferential Lamb waves, alongside the multichannel focusing, during MTRF process. By taking the direct focus as a time base, accurate defect localization is implemented. Secondly, a new phenomenon is exhibited in this paper that defect scattered wave packet appears just before the right boundary of truncation window after time reversal, and to which two feasible explanations are given. Moreover, this phenomenon can be used as the theoretical basis in the determination of defect scattered waves in time reversal response signal. At last, in order to detect defects without prior knowing their exact position, a large-range truncation window is used in the proposed method. As a result, the experimental operation of MTRF method is simplified and defect detection and localization are well accomplished.     

Parameter determination from current–voltage characteristics of HgCdTe photodiodes in forward bias region

Current–voltage characteristics of HgCdTe photodiodes in the forward bias region have been modeled considering mechanisms including drift-diffusion current, recombination current, metal-semiconductor contact and constant series resistance. Moreover, a fitting method based on the genetic algorithm has been developed to obtain values of related physical parameters from the measured dynamic resistance–voltage curves. Fitting results of $n^+$ -on- $p$ planar devices with different cutoff wavelengths are presented to illustrate the model and method, which are available and promising in acquiring device parameter values and evaluating the electrode contact quality.