Efficient Inverted Perovskite Solar Cells with a Fill Factor Over 86% via Surface Modification of the Nickel Oxide Hole Contact

The poor interface quality between nickel oxide (NiO_x) and halide perovskites limits the performance and stability of NiO_x-based perovskite solar cells (PSCs). Here a reactive surface modification approach based on the in situ decomposition of urea on the NiO_x surface is reported. The pyrolysis of urea can reduce the high-valence state of nickel and replace the adsorbed hydroxyl group with isocyanate. Combining theoretical and experimental analyses, the treated NiO_x films present suppressed surface states and improved transport energy level alignment with the halide perovskite absorber. With this strategy, NiO_x-based PSCs achieve a champion power conversion efficiency (PCE) of 23.61% and a fill factor of over 86%. The device's efficiency remains above 90% after 2000 h of thermal aging at 85 °C. Furthermore, perovskite solar modules achieve PCE values of 18.97% and 17.18% for areas of 16 and 196 cm², respectively.     

考虑双目竞争视觉现象的非对称失真立体图像质量评价方法

目的 现有方法存在特征提取时间过长、非对称失真图像预测准确性不高的问题,同时少有工作对非对称失真与对称失真立体图像的分类进行研究,为此提出了基于双目竞争的非对称失真立体图像质量评价方法。方法 依据双目竞争的视觉现象,利用非对称失真立体图像两个视点的图像质量衰减程度的不同,生成单目图像特征的融合系数,融合从左右视点图像中提取的灰度空间特征与HSV （hue-saturation-value）彩色空间特征。同时,量化两个视点图像在结构、信息量和质量衰减程度等多方面的差异,获得双目差异特征。并且将双目融合特征与双目差异特征级联为一个描述能力更强的立体图像质量感知特征向量,训练基于支持向量回归的特征—质量映射模型。此外,还利用双目差异特征训练基于支持向量分类模型的对称失真与非对称失真立体图像分类模型。结果 本文提出的质量预测模型在4个数据库上的SROCC （Spearman rank order correlation coefficient）和PLCC （Pearson linear correlation coefficient）均达到0.95以上,在3个非对称失真数据库上的均方根误差（root of mean square error,RMSE）取值均优于对比算法。在LIVE-II（LIVE 3D image quality database phase II）、IVC-I（Waterloo-IVC 3D image qualityassessment database phase I）和IVC-II （Waterloo-IVC 3D image quality assessment database phase II）这3个非对称失真立体图像测试数据库上的失真类型分类测试中,对称失真立体图像的分类准确率分别为89.91%、94.76%和98.97%,非对称失真立体图像的分类准确率分别为95.46%,92.64%和96.22%。结论 本文方法依据双目竞争的视觉现象融合左右视点图像的质量感知特征用于立体图像质量预测,能够提升非对称失真立体图像的评价准确性和鲁棒性。所提取双目差异性特征还能够用于将对称失真与非对称失真立体图像进行有效分类,分类准确性高。     

BS-PT基高温压电超声换能器研究

针对高温超声检测技术的应用需求,该文研究了基于钪酸铋-钛酸铅(BS-PT)基高温压电陶瓷材料的高温超声换能器。利用PiezoCAD器件仿真软件设计并制作了一款1 MHz的高温压电超声换能器,且在200 ℃下对该器件的电学和声学性能进行了测试和分析。结果表明,随着测试温度的升高,换能器的脉冲回波幅值虽略有降低,但其中心频率、带宽变化不明显,带宽仍保持在20%左右。该文设计并制备的BS-PT基高温压电超声换能器可以在200 ℃环境中正常稳定工作。     

不确定性环境下基于深度强化学习的综合能源系统动态调度

随着综合能源系统中间歇性能源和负荷不确定性的逐步增强,传统的调度方法局限于固定物理模型及参数设定,难以较好地动态响应源荷的随机波动。针对这一问题,提出了一种基于深度强化学习的综合能源系统动态调度方法。首先,以数据驱动方式构建面向综合能源系统的深度强化学习模型,通过智能体与综合能源系统的持续交互,自适应学习调度策略,降低对物理模型的依赖程度。其次,通过添加随机扰动的方式表征源荷不确定性变化特征,针对不确定性变化特征改进深度强化学习模型的状态空间、动作空间、奖励机制以及训练流程等关键环节,并经由近端策略优化算法优化求解,实现了综合能源系统的动态调度决策。最后,通过算例仿真验证了所提方法在不同时间尺度以及不确定性环境下的可行性和有效性。     

嵌入式电子助力转向系统研究

电子转向助力技术能够有效驱动汽车转向,为提高其转向控制的稳定性和准确性,本文设计了一种基于嵌入式的电子助力转向系统。首先针对传统的电子助力转向系统,利用牛顿第二定律建立其动力学模型,为控制器设计及构建硬件环境奠定基础。其次,针对典型电子转向助力系统的动力学模型,为降低其运动副间的摩擦对控制性能的影响,设计了自适应摩擦前馈补偿控制器,并根据Lyapunov稳定性原则确定了自适应控制率解析表达式。再次,本文以STM32F407嵌入式控制器为核心,搭建系统硬件平台并设计软件流程。最后,基于此平台展开试验验证,系统通过跟踪阶跃指令和正弦指令对比分析了传统PID算法和自适应摩擦前馈补偿算法,试验结果表明自适应前馈补偿算法可提高系统稳态精度和动态响应能力,并验证所设计的基于嵌入式的电子助力转向系统的正确性和完整性。     

“轨道角动量:从经典光学到量子信息”专辑前言北大核心CSCD

光子既是经典信息也是量子信息的理想载体。单个光子不仅可以携带自旋角动量,还可以携带轨道角动量。自旋角动量的研究历史比较悠久,早在1909年, Poynting就将宏观上光波的圆偏振态和微观上单个光子的自旋角动量联系起来。但直到1992年,荷兰Leidon大学的Allen等才在理论上确认光子也可以携带另外一种形式的角动量――轨道角动量,它来源于光波的螺旋相位。     

Consolidation of Cr3C2 doping WC–1TiN–5MgO micro–nano composites by two-step sintering

The effect of Cr₃C₂ additions on WC–1TiN–5MgO composites by two-step hot-pressing sintering (heated to 1750°C and then immediately cooled to 1575°C with a soaking time of 60?min under a sintering pressure of 50?MPa) was comprehensively investigated. The microstructure was characterized by means of scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray diffractometry (XRD). Mechanical properties, such as hardness, transverse rupture strength, and fracture toughness, were measured. The experimental results show that no η-phase or brittle phases such as W₂C were formed, and excellent mechanical properties were achieved for 0.6?wt.% Cr₃C₂ additions with a hardness of 24.76?GPa, a flexural strength of 1257.1?MPa, and a fracture toughness of 10.08?MPa?·?mm^1/2. Cr₃C₂ addition brought about an improvement in the sinterability and contributed to the homogeneous distribution of second phase nanosized MgO. Crack deflection and crack bridging are the major mechanisms contributing to the drastically enhanced flexural strength and fracture toughness.     

Tuning the temperature coefficient of resonant frequency for 8-layer twinned hexagonal perovskite Ba<Subscript>8</Subscript>ZnTa<Subscript>6</Subscript>O<Subscript>24</Subscript> ceramics

High-Q dielectric materials ilmenite MgTiO₃, columbite MgNb₂O₆ and cubic perovskite Ba₃NiTa₂O₉ with negative temperature coefficient of resonant frequency (τ _f ) were selected as candidates for compensating the τ _f of hexagonal perovskite Ba₈ZnTa₆O₂₄. X-ray diffraction data shows that Ba₈ZnTa₆O₂₄ coexists with Ba₃NiTa₂O₉ but is not compatible with MgTiO₃ and MgNb₂O₆ at high temperature. The τ _f for the mixed hexagonal/cubic perovskite Ba₈ZnTa₆O₂₄–Ba₃NiTa₂O₉ system is tunable via the temperature compensation effect and its quality factor may be improved via annealing the ceramics at high temperature to enhance the cation ordering in the cubic component. Permittivity ε _r  ~ 22–25, Q×f > 30,000 GHz and tunable τ _f within ±10 ppm/°C were achieved in the range of about 50–80 wt% Ba₃NiTa₂O₉ for the hexagonal/cubic perovskite composite Ba₈ZnTa₆O₂₄–Ba₃NiTa₂O₉ ceramics, which is suitable for the application as dielectric resonators and filters.     

海藻酸钠纳米粒制备的研究进展

纳米粒药物载体能帮助药物靶向传输及可控释放,是生物医药领域的重要研究方向。海藻酸钠生物相容性好、易于修饰及加工形成微纳米颗粒,作为药物载体的应用研究日渐增多。综述了制备海藻酸钠纳米粒的4种方法,即离子交联法、乳化法、静电络合法和自组装法,并指出了4种方法的优缺点。