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971.
972.
色散缓变光纤中的脉冲宽度研究 总被引:1,自引:1,他引:0
计算了高斯型脉冲宽度在色散缓变光纤中的传播特性和初始啁啾对脉宽演变的影响。讨论发现与单模光纤相比,色散缓变光纤中脉冲展宽较慢,并能有效抑制脉冲展宽;初始啁啾对脉宽有较大影响,初始啁啾参量C过大会造成脉冲严重展宽。 相似文献
973.
974.
Dissolved Cu(II) speciation in unpolluted soil solutions from different horizons was studied using differential pulse anodic stripping voltammetry (DPASV). Three sites were selected according to topography and monitored for three years. Experiments evidence Cu(II) can be bound by DOM (Dissolved Organic Matter) through complexation and/or adsorption reactions. The complexation capacity and the corresponding conditional stability constant were determined for complexation reactions. The adsorbing sites were titrated. A potential binding coefficient was calculated to compare both types of reactions. Results show adsorption is less frequent than complexation but exhibits higher binding coefficient. 相似文献
975.
The results obtained in investigating the creep of expanded polystyrene (EPS) boards under compressive stress are presented. Power and exponential equations were used for describing creep compliance. It was found that the curves of creep compliance approximated by both equations adequately represent the research results, taking into account the scatter of the experimental data. Based on the calculation and empirical estimate of long-term creep of EPS under compressive stress σc=(0.25–0.45)σ10%, its creep compliance was determined for a period of 10 years in the future. The dependence of on the density of polystyrene boards and the value of long-term compressive stress σc was established. The expected values of creep strain development in expanded polystyrene boards EPS 80–EPS 250 under constant compressive stress σc=(0.25–0.45)σ10% are presented for the prediction period of 10 years. To obtain the expected creep values for any other period of time in the interval of 5T50 years, the values of should be multiplied by the empirical coefficient . 相似文献
976.
The concept of coefficient shift matrix is introduced to represent delay variables in block pulse series. The optimal control of a linear delay system with quadratic performance index is then studied via block pulse functions, which convert the problems into the minimization of a quadratic form with linear algebraic equation constraints. The solution of the two-point boundary-value problem with both delay and advanced arguments is circumvented. The control variable obtained is piecewise constant. 相似文献
977.
978.
报道了一种主要用作超高速光纤通信系统的新型半导体光源,即超高速10 GHz、多量子阱、主被动混合锁模的半导体激光器,其输出光波长可精确稳定在1550 nm,这对实现光时分复用技术高质量超短相干脉冲光源具有重要意义。 相似文献
979.
杨震华 《核聚变与等离子体物理》1988,(2)
本文用宏观处理的方法,研究了强流相对论电子束在等离子体内引起的回流电流效应。通过Fourier变换的方法,求得Maxwell方程组的电场表达式和回流电流的径向表达式。在4στ>>1的极限下,电子束通道内的回流电流和入射的电子束电流基本抵消。最后,比较了回流电流的焦耳热和束电子与等离子体粒子库仑碰撞的能耗值。 相似文献
980.
Pulse radiolysis technique has been used to characterise the transients formed by the reaction of sulphacetamide with eaq
- and subsequently study the electron transfer reactions from the transient to various electron acceptors such as thionine,
safranine-T and methyl viologen. The results indicate that the semi-reduced sulphacetamide species are highly reducing in nature as they
transfer electrons to various dyes with near diffusion controlled rates (k > 109dm3mol−1s−1) in alkaline and acidic solutions. The influence of oxygen on the decay behaviour of semi-reduced species has been investigated
and the results show that O2 reaction with SA− is very fast (k = 1.5 × l09dm3mol−1s−1) and leads to the formation of a permanent-coloured product. Reactions of H.atoms resulted in the formation of two transient
species whose spectral, kinetic and acid-base characteristics have also been investigated. 相似文献