Inverse scattering for conductors by the equivalent source method

The inverse scattering for two-dimensional conductors is investigated. Assume that an incident wave is incident upon conducting cylinders of unknown shape and the scattered field is measured outside. By properly processing the scattering data, the position and shape of the conducting scatterers can then be reconstructed. The proposed theory of inverse scattering is a combination of the diffraction tomography and the equivalent source method. To overcome the ill-posedness, the condition of the measured scattered field and the boundary condition on the conductor surfaces are combined and recast into an optimization problem using the least-squares concept. By comparing the reconstructed and the prescribed results, the inversion algorithms are numerically examined. Note that if a priori information of the shape is sufficient and the equivalent sources are properly placed, the algorithms can be flexibly applied to the cases of multiple conductors. Also the effects of noise contamination and multiple scattering on the reconstruction result are numerically investigated     

Simple method for mitigation of polarization crosstalk in silica planar lightwave circuit directional couplers

Polarization crosstalk in planar lightwave circuit directional couplers can cause significant polarization-dependence in interferometers that use them. We show a simple way to mitigate the polarization crosstalk without incurring a performance penalty or requiring extra fabrication steps. We demonstrate it on a 23-ps Mach-Zehnder delay interferometer.     

Efficient Two‑Dimensional Perovskite Solar Cells Realized by Incorporation of Ti3C2Tx MXene as Nano‑Dopants

Two-dimensional(2D)perovskites solar cells(PSCs)have attracted considerable attention owing to their excellent stability against humidity;however,some imperfectness of 2D perovskites,such as poor crystallinity,disordered orientation,and inferior charge transport still limit the power conversion efficiency(PCE)of 2D PSCs.In this work,2D Ti3C2Tx MXene nanosheets with high electrical conductivity and mobility were employed as a nanosized additive to prepare 2D Ruddlesden–Popper perovskite films.The PCE of solar cells was increased from 13.69(without additive)to 15.71%after incorporating the Ti₃C₂T_x nanosheets with an optimized concentration.This improved performance is attributed to the enhanced crystallinity,orientation,and passivated trap states in the 3D phase that result in accelerated charge transfer process in vertical direction.More importantly,the unencapsulated cells exhibited excellent stability under ambient conditions with 55±5%relative humidity.     

Experimental Investigation of Heat Transfer in Microchannel with Inlet Cavitation Structure

Heat transfer of R134 a through the microchannel with an inlet reentrant cavitation structure was investigated for high flux thermal management of electronic devices.The cavitating flow patterns,pressure,and heat transfer characteristics were studied in the range of effective heat fluxes from 0 to 138.4 W/cm2 with mass flow velocities from 2.12 to 5.23 m/s.A stable and ideal starting point of two phase flow and heat transfer was commendably provided by the inlet cavitation orifice.There existed an axis deviation liquid jet after the micro-orifice.The refrigeration vapor was generated from the cavitation structure but liquidized at the downstream of the channel.The wall temperature along flow orientation presented an opposite trend under the test states with or without heat input.The cavitation structure can significantly suppress the flow oscillation in microchannels and the outlet pressure fluctuation reduced about 72%compared with the fluctuation at the entrance.The heat transfer coefficient had been distinctly impacted by heat flux at lower heat input and then maintained the value nearly constant of 11.0 W/(cm²·K)with the critical heat flux of 88.4 W/cm2.     

全日制学科教学（英语）专业课程群建设研究

课程群建设是当前高等教育课程体系改革的重要内容,构建学科教学（英语）专业的课程群具备一定可行性,其具有课程内容交叉融合度高、实践教学环节丰富、适应专业发展需求等特征。为进一步提高学科教学（英语）专业研究生的培养质量,探索新形势和新要求下学科教学（英语）专业的发展路程,需要从教学大纲、教学内容、教学理念、教学资源等方面进行专业课程群构建。     

叶绿素荧光量子产量的MODIS遥感算法

从荧光量子产量的原理出发,利用 MODIS 卫星数据建立了一种估算量子产量的算法--φ算法.通过 2006 年 3 月 23 日渤海和北黄海的 MODIS 数据计算了荧光量子产量,并与叶绿素荧光效率(cFE)产品进行了比较.结果表明,φ算法是一种更精确的荧光量子产量的估算算法,它有效地避免了 CFE 存在的几个误差来源:包括未考虑浮游植物的"包裹效应"、使用 412nm 的离水辐亮度反演的浮游植物吸收系数以及积分深度过浅.CFE在大部分海域出现负值,还出现了某些高估点;在有效数据范围内,两者存在明显的线性相关关系.φ算法估算的量子产量最高值在0.05左右,这与其它海区测量的值域范围基本一致.除辽东湾东北部和部分近岸水域外,大部分离岸水域在0.001～0.02的范围内.通过对φ算法的误差来源分析,认为发展一种新的反演 678nm 比吸收系数和平均吸收系数的波段比值算法是可行的,也是改进φ算法精度的有效方法.     

高马氏体量双相钢的组织与性能研究

通过光镜、扫描电镜分析以及拉伸试验研究了高马氏体量双相钢(马氏体体积分数大于30%)在不同热处理条件下的显微组织和拉伸性能,并进一步探讨了其断裂机理.结果表明,随着两相区保温温度的升高,马氏体体积分数不断升高,导致强度不断提高.马氏体体积分数较低时,钢的断裂特征为韧性断裂;马氏体体积分数较高时,则会转变为脆性断裂.微孔在断裂表面附近形成.微孔的形态随着马氏体的比率而变化,随着马氏体体积分数的升高,微孔形态从界面结合力的丧失转为微裂纹.     

基于低温直接键合的血细胞计数芯片结构制备

研究了一种新颖的微流管道血细胞计数器的结构及其工作原理,采用流体动力学对其液体分层流动特性进行了仿真分析,结合图形制备和低温直接键合工艺制作了硅基微流体管道血细胞计数器结构,并采用红外透射方法对微流体管道结构进行了检测.对封闭管道的流通性及结构的键合强度也进行了测量.研究分析表明,采用上述工艺制备的微流体芯片结构与电子器件兼容性好,具有良好的化学惰性和热稳定性,而且管道结构规则,精度高,键合界面层薄,具有较好的应用前景.     

Dynamic Decoupling for Combined Shape and Gauge Control System in Wide Strip Rolling Process

The precision of profile and thickness is the most important target for wide strip rolling,but the coupling of profile control and thickness control is ignored in rolling schedule,which holds down the simultaneous quality improvement of profile and thickness.A cross-coupled process control model for combined shape and gauge control was developed on the basis of the fact that both controls for profile and thickness are realized by controlling the rolling gap.A dynamic decoupling controller was then proposed to decouple the model.Both the simulation results and the online production data are valid and ensure the quality of the decoupling controller.