人工神经网络X射线荧光光谱法测定钢中酸溶铝

建立了一种人工神经网络-X射线荧光光谱法测定钢中酸溶铝的方法，用X射线荧光光谱法测定低合金钢中总铝值，应用所建立的ANN-BP网络模型，输入总铝含量直接预测出酸溶铝含量。同时使用改进的BP算法，避免了神经网络学习中可能产生的麻痹现象。该方法用于钢中酸溶铝的测定，结果满意。     

基于规范图像的光电成像系统采样响应研究北大核心CSCD

为了研究采样响应对光电成像系统生成图像的质量的影响,本文提出了将规范图像作为输入建立封闭的模型来分析采样响应的方法。首先给出了规范图像的定义并得到了USAF 1951规范图像的数学模型,然后分析了光电成像系统的采样响应过程和采样响应函数,最后讨论了USAF 1951规范图像在不同条件下的采样响应结果。研究结果表明:当采样前MTF截止频率、采样频率与采样后MTF截止频率之间的关系不同时,采样响应对像质的影响不同;当采样频率与采样前MTF截止频率满足一定的条件时,可在图像模糊与混叠之间取得平衡。     

基于自适应对比度增强的红外小目标检测网络

红外探测系统需要尽早发现目标以便及时拦截,但是红外图像上的小目标检测是一个挑战十足的任务。为了提高检测准确率,提出一种基于自适应对比度增强的红外小目标检测方法。为了利用自注意力机制和卷积各自的优势,设计了一个高效的特征提取网络和一个面向小目标的检测头。同时为了解决实际应用中出现的弱目标,在检测子网络前添加了一个图像预处理子网络,该模块可以自适应地调节图像对比度。在红外空中小目标数据集上的实验表明,提出的方法能达到93.76%的检测精度,与经典的检测方法相比,能够更好地平衡检测精度和召回率,证明了方法的巨大应用潜力。     

基于双解码路径DD-UNet的脑肿瘤图像分割算法

针对医学图像中病灶区域尺度不一、边界模糊和周围组织强度不均匀所导致的分割精度降低问题,提出了一种基于双解码器的脑肿瘤图像分割模型。为了增强特征的表征力,提出了高阶微分残差模块并使用不同空洞率的扩张卷积用于提取特征编码,提高了网络模型的分割性能;引入上下文语义信息感知模块(multi scale dilation, MSD),从不同的目标尺度中提取更多的精细信息,提高了对结构细节信息的捕获能力,同时减少了编解码器之间的特征差异;在空间解码路径中使用选择性聚合空间注意力模块(spatial aggregation attention module, SAAM),增加了对有效空间特征的权重比例,减少了无效的特征干扰。在脑肿瘤数据集上进行了实验验证,实验结果表明,所提算法的Dice系数、平均交并比、敏感性、特异性、准确率等指标分别为：93.35%、90.71%、91.15%、99.94%、96.75%。     

Blood cell counting based on U-Net++ and YOLOv5

Clinical information about a variety of disorders is available through blood cell counting, which is usually done by manual methods. However, manual methods are complex, time-consuming and susceptible to the subjective experience of inspectors. Although many efforts have been made to develop automated blood cell counting algorithms, the complexity of blood cell distribution and the highly overlapping nature of some red blood cells (RBCs) remain significant challenges that limit the improvement of analytical accuracy. Here, we proposed an end-to-end method for blood cell counting based on deep learning. Firstly, U-Net++ was used to segment the whole blood cell image into several regions of interest (ROI), and each ROI contains only one single cell or multiple overlapping cells. Subsequently, YOLOv5 was used to detect blood cells in each ROI. Specifically, we proposed several strategies, including fine classification of RBCs, adaptive adjustment for non-maximal suppression (NMS) threshold and blood cell morphology constraints to improve the accuracy of detection. Finally, the detection outcomes for each ROI were combined and superimposed. The results show that our method can effectively address the issue of high overlap and precisely segment and detect blood cells, with a 98.18% accuracy rate for blood cell counting.     

Mo-Modified ZnIn2S4@NiTiO3 S-Scheme Heterojunction with Enhanced Interfacial Electric Field for Efficient Visible-Light-Driven Hydrogen Evolution

Designing and developing visible-light-responsive materials for solar to chemical energy is an efficient and promising approach to green and sustainable carbon-neutral energy systems. Herein, a facile in situ growth hydrothermal strategy using Mo-modified ZnIn₂S₄ (Mo-ZIS) nanosheets coupled with NiTiO₃ (NTO) microrods to synthesize multifunctional Mo-modified ZIS wrapped NTO microrods (Mo-ZIS@NTO) photocatalyst with enhanced interfacial electric field (IEF) effect and typical S-scheme heterojunction is reported. Mo-ZIS@NTO catalyst possesses wide-spectrum light absorption properties, excellent visible light-to-thermal energy effect, electron mobility, charges transfer, and strong IEF and exhibits excellent solar-to-chemical energy conversion for efficient visible-light-driven photocatalytic hydrogen evolution. Notably, the engineered Mo_1.4-ZIS@NTO catalyst exhibits superior performance with H₂ evolution rate of up to 14.06 mmol g⁻¹ h^{− 1} and the apparent quantum efficiency of 44.1% at 420 nm. The scientific explorations provide an in-depth understanding of microstructure, S-scheme heterojunction, enhanced IEF, Mo-dopant facilitation effect. Moreover, the theoretical simulations verify the critical role of Mo element in promoting the adsorption and activation of H₂O molecules, modulating the H adsorption behavior on active S sites, and thus accelerating the overall catalytic efficiency. The photocatalytic hydrogen evolution mechanism via S-scheme heterojunction with adjustable IEF regulation over Mo_1.4-ZIS@NTO is also demonstrated.     

小型化低功耗机载显示器图形系统设计与实现

为了满足机载显示器图形生成系统的小尺寸、低功耗需求,提出了一种基于龙芯2K1000的全国产图形生成与处理方案。该方案以2K1000为核心构建硬件平台,使用2K1000内部集成的中央处理器、图形处理器、显示控制器,以及外部的内存实现图形的计算生成和双缓存显示,配合国产可编程逻辑器件实现图形与外视频的叠加显示及机载通信总线扩展。软件上采用航空专用的国产天脉操作系统,基于天脉操作系统设计了关键的图形显示驱动、帧存驱动、显示控制器驱动。实验结果表明,在输出1 024 pixel×768 pixel分辨率显示时,典型机载图形画面帧率达到35 frame/s,整体功耗约10 W。该方案扩展性强、功耗低,满足实时显示需求,在机载显示器领域有着广泛的应用空间。     

电磁散射特征提取与成像识别算法综述

合成孔径雷达(SAR)图像的自动化解译是合成孔径雷达技术应用的重要发展方向之一。电磁散射特征与目标结构具有稳健的关联性,是SAR图像解译的关键支撑。近年来,如何准确地实现电磁特征提取以及利用电磁特征反演目标特性受到了广泛的重视。该文讨论了电磁特征提取和基于电磁散射特征识别方法的研究成果,总结归纳了其中的关键要素和主要思路,详述了电磁散射机理在成像和识别领域的扩展应用,展望了未来电磁散射特征提取与应用的研究发展趋势。      

Upconversion fluorescence modulation of CaTiO3:Yb3+/ Er3+ nanocubes via Zn2+ introduction

rials, CaTiO3:Yb3+/Er3+/Zn2+ nanocubes with uniform size were prepared by solvothermal method in this paper. They were respectively characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), photoluminescence (PL) spectroscopy and their fluorescence lifetimes. The results show that the average size of the nanocubes is about 550 nm×650 nm×850 nm with good upconversion luminescence (UCL) properties. Under 980 nm laser excitation, the effects of the ratio between activator Er3+ and sensitizer Yb3+ and Zn2+ doping on the upconversion fluorescence properties were investigated, and the optimal ion ratio was obtained. The results of steady-state spectra show that the strongest fluorescence intensity of CaTiO3:Yb3+/Er3+ was obtained with the addition of 10 mol% Zn2+ at a Yb3+/Er3+ molar doping ratio of 3:0.3, which was attributed to the crystal field asymmetry generated by the introduction of Zn2+ ions. The energy transfer and upconversion mechanism between Yb3+ and Er3+ ions in CaTiO3 nanocubes were investigated by analyzing the upconversion fluorescence kinetics.