PMD Measurement of Hollow-Core Photonic Bandgap Fiber by Investigating Power Penalty of Optically Generated Microwave Signals

A simple method based on carrier suppression modulation for measuring first-order polarization-mode dispersion of hollow-core photonic bandgap fiber (HC-PBGF) is proposed and investigated. By adjusting the incident optical wavelength and measuring the power penalty of optically generated microwave signals, the wavelength-dependent differential group delay (DGD) in HC-PBGF can be obtained. Moreover, this proposed method is chromatic-dispersion-insensitive. The experimental results indicate that a segment of 20-m HC-PBGF exhibits highly birefringent DGD of 25, 59, and 84 ps with measurement error less than 2 ps for the incident optical wavelength of 1560, 1575, and 1580 nm, respectively     

聚苯乙烯溴代并接技聚二甲基硅氧烷

聚苯乙烯（PS）在苯溶液中与溴代丁二酰亚胺（NBS）反应，经分离提纯得到了固体溴代聚苯乙烯（PSB）。将所得PSB溶于苯并与低分子量的聚二甲基硅氧烷硅醇锂（PDMSOLi）反应，经分离提纯得到固体的溴代聚苯乙烯接枝聚二甲基硅氧烷（PSB－g-PDMSO),所得PSB-g-PDMSO的结构经^1H-NMR、IR及TEM表征。     

Data mining of resilience indicators

In recent years, the Asia-Pacific region has experienced several financial setbacks, including speculative attacks in 1998 and the SARS outbreak in 2003. Financial stresses of this nature are unanticipated, and not all of the dangers can be predicted by the examination of market information and macroeconomic indicators. The Early Warning System (EWS) that has been adopted by the International Monetary Fund may not be able to predict future financial crises for all possible scenarios, because shocks come in many different forms. To supplement the EWS, this paper proposes a data mining framework to measure the resilience of an economy. The resilience framework does not predict a crisis, but rather assesses the current state of health of an economy and its ability to withstand a financial shock should one occur. The framework is based on a feedback system consisting of two stages. The first stage assigns a resilience score to each economy based on a fuzzy logic scoring scheme that is built on the ambiguous reasoning of experts. The second stage uses the classification tree approach to estimate thresholds for each economic indicator, and examines the quality of the fuzzy score. The result from the second stage is then passed back to the first stage as feedback. The final result is obtained when the feedback system reaches its equilibrium state. The proposed resilience framework is applied to the external-sector and the public-sector economies of several countries to illustrate its applicability.     

Hydriding and Dehydriding Characteristics of Mechanically Alloyed LaMg_(17) Ni Composite Material

Magnesiumandmagnesiumalloyshavebeenin vestigatedashydrogenstoragematerialsforseveralde cadesbecausefarmorehydrogenbyweightcanbestoredinthemthaninmostoftheothercurrentlyknownhydrogenstoragealloys .Moreover ,thehighnaturalabundanceofMg ,itslightmassandenviron mentalcompatibilitypotentiallymakemagnesiumoneofthemostprospectivecandidatesforfuturehydrogenstoragematerials .Unfortunately ,thepracticalappli cationofMganditsalloyshasbeenlimitedonlytocertainstoragedevicebecauseoftheirpoorhydriding dehydr…     

有色金属行业信息化述评

通过大量调查资料 ,分析有色金属行业信息化建设的现状、存在的差距和问题 ,探讨了有色信息化建设面临的形势和要求、方向和任务。     

酚醛树脂复合板在热连轧机中的应用

重点分析了现有F7机架出口导卫装置的情况。原导卫材料是由铸钢制造 ,由于摩擦和高温常常引起热连轧带钢表面划伤 ,根据现场实际情况用酚醛树脂复合板替代铸钢导卫装置。实践表明 ,这种改造即可行又可靠 ,并取得了好的效果     

Convergence of simultaneous perturbation stochastic approximation for nondifferentiable optimization

We consider simultaneous perturbation stochastic approximation for function minimization. The standard assumption for convergence is that the function be three times differentiable, although weaker assumptions have been used for special cases. However, all work that we are aware of at least requires differentiability. We relax the differentiability requirement and prove convergence using convex analysis.     

纳米技术在中药开发中的应用

本文综述了纳米科技与中药制剂相结合的发展，阐述了纳米中药的概念、特性，介绍了纳米中药的制备技术，另外探讨了收集纳米粒子的方法，最后，着重展望了纳米技术在中药制剂中广泛的应用前景。