浅议珠心算教学中的情景设计

抓住幼儿个性特征,紧密结合教学内容,有意创设教学情景,不仅可以激励学生学习,而且还可以提高学习效率。我在近几年珠心算教学实践中,针对4-7岁幼儿活泼好动、好胜心强和可塑性大的特点,在教学中开展各种情景教学活动,以直观、生动、形象的情景设     

A novel dual-wavelength fiber Bragg grating and its application in fiber ring laser

A novel method for fabricating dual-wavelength fiber Bragg gratings (FBGs) by using one phase mask is developed. The method is based on a double-exposure technique. Our technique lends itself to writing gratings with controllable reflectivity and separation of two Bragg wavelengths. A grating with two equal transmission peaks of 20.25 dB is obtained by this method and the separation of the two Bragg wavelengths is about 0.8 nm. With the grating, we demonstrate a dual-wavelength erbium-doped fiber ring laser whose interval of the two peaks is 0.8 nm. The laser's peak powers can get 3.1 mW above and have a good stability.     

Synthesis, MSssbauer Spectra and Magnetic Properties of Quasi-One-Dimensional Fe3O4 Nanowires

Quasi-one-dimensional Fe3O4 nanowires in diameter of about 200nm were assembled into anodic aluminium oxide templates via electrodepositing and heat-treating processes. The nanowires have a polycrystalline spinel structure with α=8.317А, and each nanowire is composed of fine Fe3O4 crystallites with size of about 30nm.     

Photon—Storage in Optical Memory Cells Based on a Semiconductor Quantum Dot—Quantum Well Hybrid Structure

We report a new type of photonic memory cell based on a semiconductor quantum dot (QD)--quantum well (QW) hybrid structure, in which photo-generated excitons can be decomposed into separated electrons and holes, and stored in QW and QDs respectively. Storage and retrieval of photonic signals are verified by time-resolved photoluminescence experiments. A storage time in excess of l00ms has been obtained at a temperature of 10K while the switching speed reaches the order of ten megahertz.     

InAIAs／InGaAs／IIAlAs量子阱高迁移率二维电子气系统中的反弱局域效应研究

研究了si重δ掺杂In0．52Al0.48/In0.53Ga0.47As／In0.52Al0.48As单量子阱内高迁移率二维电子气系统中的反弱局域效应．研究表明，强的Rashba自旋轨道相互作用来源于量子阱高的结构反演不对称．高迁移率系统中，粒子的运动基于弹道输运而非扩散输运．因此，旧的理论模型不能用于拟合实验结果．由于最新的模型在实际拟合中过于复杂，一种简单可行的近似用于处理实验结果，并获得了自旋分裂能△。和自旋轨道耦合常数a两个重要的物理参数．该结果与对纵向电阻的Shubnikov-de Haas--SdH振荡分析获得的结果一致．高迁移率系统中的反弱局域效应研究表明，发展有效的反弱局域理论模型，对于利用Rashba自旋轨道相互作用来设计自旋器件尤为重要.     

Quintessence Contribution to a Schwarzschild Black Hole Entropy

The quintessence contribution to a Schwarzschild black hole entropy is thoroughly investigated by using the improved brick-wall model. It is found that due to the present of the quintessence, there are two horizons, one is the cosmological horizon, and the other is the black hole horizon. By regulating the cut-off factor ε and the thickness of the thin layer 5, we obtain that the entropy of the system is 1/4 of the sum of the areas of the two event horizons.     

Fibre Bragg Gratings Inscribed in Homemade Microstructured Fibres

Fibre Bragg gratings （FBGs） are inscribed in homemade microstructured fibres by the standard phase mask method. Enhanced couplings between the forward fundamental mode and backward cladding modes are obtained. The mode coupling and spectral characteristics are investigated experimentally. The cladding mode resonances can be affected by filling active materials into the air holes, which will be useful for the implementation of tunable photonic devices in optical fibre communication and sensing systems.     

Improved Performance of Organic Thin Film Transistor with an Inorganic Oxide/Polymer Double-Layer Insulator

We employ the Ta2Os/PVP （poly-4-vinylphenol） double-layer gate insulator to improve the performance of pentacene thin-film transistors. It is found that the double-layer insulator has low leakage current, smooth surface and considerably high capacitance. Compared to Ta205 insulator layers, the device with the Ta2Os/PVP doublelayer insulator exhibits an enhancement of the field-effect mobility from 0.21 to 0.54 cm2/Vs, and the decreasing threshold voltage from 4.38 V to -2.5 V. The results suggest that the Ta2Os/PVP double-layer insulator is a potential gate insulator for fabricating OTFTs with good electrical performance.     

多台电軸系統的稳定性及非线性振盪問题

<正> §1.引言 交流电軸早巳得到应用,但以两台电軸为常見,如閘門、吊桥及机床等設备.因电軸系統有它的特殊优点,簡单可靠,維护方便,可以代替机械軸,所以随着工业的发展,很多重要的多电动机拖动系統也逐漸采用电軸,电軸在这些多电机拖动系統的采用要求我們深入研究多台电軸系統的稳定性及振盪問題.这里遇到多自由度非綫性二次联立方程,