大型工业轧机的三维板带轧制解析

针对传统理论的不足,并考虑到板带的横向流动,建立了板带轧制的三维解析模型.数值解析给出了单位轧制压力、出口断面形状、边部减薄及宽展等计算结果,且不同轧制条件下的计算实例与实际相吻合,表明所开发的三维程序适用于单机架或连轧机组等不同型式的宽、窄带钢轧制解析.     

Differences in lithospheric structures between two sides of Taihang Mountain obtained from the Zhucheng-Yichuan deep seismic sounding profile

A 2-D model of lithospheric velocity structures in the southern part of the North China Craton was obtained using data from the Zhucheng-Yichuan deep seismic sounding profile.Results show that there are great differences in lithospheric structures between two sides of Taihang Mountain.In the eastern region,the lithosphere is thinner,with a thickness of about 70-80 km,while in the western region,the thickness is 85-120 km.There is a jump of the lithospheric thickness across Taihang Mountain gravity anomaly b...     

A Composite Formation Route to Well‐Crystalline Manganese Oxide Nanocrystals: High Catalytic Activity of Manganate–Alumina Nanocomposites

Manganese oxide nanocrystals are combined with aluminum oxide nanocrystals to improve their crystallinity via calcination without a significant increase of crystal size. A nanocomposite, consisting of two metal oxides, can be synthesized by the reaction between permanganate anions and aluminum oxyhydroxide keggin cations. The as‐prepared manganese oxide–aluminum oxide nanocomposite is X‐ray amorphous whereas heat‐treatment gives rise to the crystallization of an α‐MnO₂ phase at 600 °C and Mn₃O₄/Mn₂O₃ and γ‐Al₂O₃ phases at 800 °C. Electron microscopy and N₂ adsorption‐desorption‐isotherm analysis clearly demonstrate that the as‐prepared nanocomposite is composed of a porous assembly of monodisperse primary particles with a size of ～20 nm and a surface area of >410 m² g^?1. Of particular interest is that the small particle size of the as‐prepared nanocomposite is well‐maintained up to 600 °C, a result of the prevention of the growth of manganate grains through nanoscale mixing with alumina grains. The calcined nanocomposite shows very‐high catalytic activity for the oxidation of cyclohexene with an extremely high conversion efficiency of >95% within 15 min. The present results show that the improvement of the crystallinity without significant crystal growth is very crucial for optimizing the catalytic activity of manganese oxide nanocrystals.     

Calibration Method of Current Meters

This paper presents a rapid method for propeller current meter calibration, enabling calibration of current meters in their actual working conditions using simpler equipment than what is currently used in traditional calibrations, and exploiting the uniform velocity profile present through submerged outflows (e.g., flow nozzles and orifices). Experiments were performed to confirm the fundamental hypothesis of uniform horizontal and vertical velocity distribution downstream of a submerged jet. Two experimental velocities were adopted to determine the calibration curve: one based on the discharge and the outflow area; the other derived from Torricelli’s formula, which relies on the head difference between two reservoir levels. Because a current meter measures local velocity, the influence on the measurements’ reliability as a function of current meter position in the submerged outflow jet was investigated. An uncertainty analysis was also performed, and a comparison of the results with the preexisting calibration lines obtained by towing tank is presented.     

以蔗糖为模板剂合成介孔氧化铝

以蔗糖为模板剂,异丙醇铝为铝源,水相体系下,考察了体系pH和模板剂用量对介孔氧化铝合成的影响。并采用X射线衍射、透射电镜(TEM)、氮吸脱附以及固体核磁等手段对合成样品进行表征。结果表明,合成的介孔氧化铝为γ-Al2O3,具有较高的比表面积以及较集中的孔径分布。体系的pH和模板剂用量对介孔氧化铝产物的性能有一定影响,并对蔗糖的模板作用机理进行了讨论。     

液相法合成氢化铝钠的研究

以NaH和AlCl3为主要原料,通过改变实验条件,探索研究液相法合成NaAlH4的合成条件。实验表明,在不加入任何催化剂的情况下无法实现NaAlH4的合成,在以NaAlH4、三乙基铝等物质为催化剂的条件下,虽有少量的产物生成,但是反应不明显,且产物中存在大量的非晶态物质。即便在高温高压下反应亦难以进行,大量的化合物均以非晶态形式存在。     

3-丙酰氨基-N,N-二丙酸甲酯基苯胺的合成研究

用无水三氯化铝作催化剂在较低温度下将3-氨基丙酰苯胺和丙烯酸甲酯转化为3-丙酰氨基-N,N-二丙酸甲酯基苯胺,其产品收率达到89%,纯度高于92%。     

Optimal power flow using differential evolution algorithm

This paper presents an efficient and reliable evolutionary-based approach to solve the optimal power flow (OPF) problem. The proposed approach employs differential evolution algorithm for optimal settings of OPF problem control variables. The proposed approach is examined and tested on the standard IEEE 30-bus test system with different objectives that reflect fuel cost minimization, voltage profile improvement, and voltage stability enhancement. The proposed approach results are compared with the results reported in the literature. The results show the effectiveness and robustness of the proposed approach.     

1.5kW激光二极管抽运Nd∶YAG薄片激光器

报道了一台输出功率超过1.5kW的激光二极管抽运Nd∶YAG双薄片激光器。设计了四通光学耦合系统,通过优化经微柱透镜准直后光束的发散角,实现了抽运光的近平顶分布。薄片激光介质镀完介质膜后镀Ti,Pt,Au实现金属化,再采用铟焊工艺焊接在铜微通道冷却器上,以提高散热效率和冷却的均匀性。采用两片直径40mm,厚度1.3mm的Nd∶YAG薄片激光介质,在两个二极管激光器阵列抽运下,当每个薄片上的抽运峰值功率为17.7kW,占空比10%时,获得了平均功率1.52kW的准连续激光输出,光-光转换效率达到43%,电-光转换效率超过20%。     

自适应距离单元积累检测法及其应用

本文提出了一种宽带毫米波雷达体制下,基于高分辨一维距离像的强地物杂波背景中目标检测新方法－自适应距离单元积累检测法。该方法表明：宽带信号提供的高径向分辨力使雷达对目标进行一维距离成像成为可能,一维距离像反映了目标强散射中心的空间分布特性,在目标检测时利用不同径向单元内的强散射中心能量进行横向积累,可以提高信杂比,从而改善检测性能。