Directional Coupler Formed by Photonic Crystal InAlGaAs Nanorods

In this paper, we demonstrate the use of photonic crystal (PC) directional couplers to separate light of wavelengths at 1.31 and 1.55 m. The PC structure consists of InAlGaAs nanorods arranged in hexagonal lattice. The simulation of our device is implemented by the finite-difference time-domain method. The devices are fabricated by e-beam lithography and conventional photolithography. We use the strong inverse method (SIM) of e-beam lithography to make the pattern smoother. The measurement results confirm that 1.31/1.55-m wavelength splitter can be realized in PC structures formed by nanorods.     

Synthesis of Neodymium-Doped Yttrium Aluminum Garnet (Nd∶YAG) Nano-Sized Powders by Low Temperature Combustion

The homogeneously dispersed, less agglomerated (Nd0.01Y0.99)3Al5O12 nano-sized powders were synthesized by the low temperature combustion (LCS), using Nd2O3, Y2O3, Al(NO3)3·9H2O, ammonia water and citric acid as starting materials. This method effectively solves the problems caused by solid-state reaction at high temperature and hard agglomerates brought by the chemical precipitation method. The powders were characterized by TG-DTA, XRD, FT-IR, TEM respectively and the photoluminescence (PL) spectra of (Nd0.01Y0.99)3Al5O12 green and sintered ceramic disks were measured. The results show that the forming temperature of YAG crystal phase is 850 ℃ and YAP crystal phase appearing during the calcinations transforms to pure YAG at 1050 ℃. The particle size of the powders synthesized by the LCS is in a range of 20～50 nm depending on the thermal treatment temperatures. The effectively induced cross section (σin) with the value 4.03×10-19 cm2 of (Nd0.01Y0.99)3Al5O12 ceramics is about 44% higher than that of single crystal.     

Upconversion Luminescence of YLiF4 :Er3+ Synthesized by Hydrothermal Method

YLiF4: Er3 was synthesized by hydrothermal method. Concentration of Er3 is changed from 0 to 5 %. The absorption of Er3 in all samples from 200 to 1200 nm was measured at room temperature. The J-O parameters calculated from absorption spectrum areΩ 2 = 1.05 × 10- 20 cm2, Ω4 = 1.25 × 10- 20 cm2 andΩ6 = 1.35 × 10- 20 cm2. Infrared-to-visible upconversion emission of YLiF4: Er3 was observed when excited by 980 nm. The results show that the Er3 content is less than 1.5 %, excite-state absorption is the main mechanism of upconversion emission. When Er3 content is larger than 1.5 %, both of the excite-state absorption and energy transfer lead to the upconversion luminescence. The upconversion intensity was enhanced with the increasing of Er3 concentration. At room temperature, the lifetime of 2H11/2 and 4S3/2is 205μs while that of 4F9/2 is 188μs for sample Er-2. The transition rates and quantum efficiency were also calculated.The quantum efficiencies of 4S3/2 and 4F9/2 are 27.9% and 10.7%, respectively.     

流域年均含沙量的PP回归预测

应用投影寻踪回归技术，建立了流域年均含沙量的预测模型。用降雨量和年平均径流等４个因子瓣某流域平均含沙量的ＰＰＲ预测结果的拟合合格率达１００％，预留检验样本报准率为７５％，表明ＰＰＲ用于泥沙输移规律的预测研究是可行的。     

An Electroabsorption Modulator Monolithically Integrated with a Semiconductor Optical Amplifier and a Dual-Waveguide Spot-Size Converter

A semiconductor optical amplifier and electroabsorption modulator monolithically integrated with a spot-size converter input and output is fabricated by means of selective area growth,quantum well intermixing,and asymmetric twin waveguide technology.A 1550～1600nm lossless operation with a high DC extinction ratio of 25dB and more than 10GHz 3dB bandwidth are successfully achieved.The output beam divergence angles of the device in the horizontal and vertical directions are as small as 7.3°×18.0°,respectively,resulting in a 3.0dB coupling loss with a cleaved single-mode optical fiber.     

A plane-strain UBET analysis of material flow in a filled deep die cavity in closed-die forging

When a deep die cavity is filled in closed-die forging, further movement of the dies will reduce the extension of the plastic region, a part of the workpiece in the cavity becoming rigid and forming dead zones. Consequently the plastic deformation is localized within a particular region, where the plastic deformation imparted could be much greater than the average. In this work, the upper-bound elemental technique (UBET) is applied to analyze the material flow in a filled deep cavity for plane-strain conditions. The boundaries between the dead zones and the deforming material are determined together with the velocity field by minimizing the total power dissipation. The boundaries are analyzed and presented numerically. Strain-rate hardening and inhomogeneous deformation in the UBET element are taken into account. A detailed formulation of the analysis is presented in the paper. The influences of flash-height and the strain-rate hardening exponent of the deforming material are studied theoretically. The results are compared with those of model-material experiments and those of commercial FEM software, satisfactory agreement being obtained.     

农业灌溉节水对策

本文以石津灌区为例：结合灌区历年输水及灌溉经验的总结与分析，针对我省干旱缺水状况，阐述了农业灌溉节水的重要性，并对节水措施与对策提出了个人浅见。     

单一水库的优化调度

本文针对以灌溉为主的中、小型水库，采用动态规划方法进行水库的优化调度，通过数学模型的建立得出最优效益值，从而为工程单位提供最优供水策略。     

The surface fractal investigation on carbon nanotubes modified by the adsorption of poly(acrylic acid)

In this paper, surface fractal analysis is carried out to study the surface of carbon nanotubes after the adsorption of poly(acrylic acid) (PAA) using the thermodynamic method. The fractal dimension (d_SF ) of a fractal surface, BET surface area (S_BET) and pore size distribution (PSD) are calculated from low-temperature nitrogen adsorption isotherms. The value of d_SF declines as the adsorption amount of PAA increases, which means the adsorption may lower the surface roughness of the carbon nanotubes. The PSD pattern was modified obviously after the adsorption of PAA because of the pore-blocking effect. Additionally, an excellent linear decrease in the BET surface area of carbon nanotubes is found as the adsorption amount of PAA increases, which can be attributed to both the pore-blocking effect and the surface-screening effect. The results of the present work may facilitate our understanding of the interaction between polymer and the carbon nanotubes at the microscale occurring on irregular interfaces.     

电缆输送过油管射孔工艺技术在玉门油田的应用

针对青西油田老井侧钻、加深及部分深井小井眼完井不能采用常规射孔器射孔现状,选用无枪身射孔工艺,解决了完井难题,探索出一套无枪身射孔器射孔的施工方法,提高了施工井的成功率,为今后实施该项工艺积累了经验。