Power-efficient grating-based scanning optical delay line: time-domain configuration

A power-efficient, grating-based, time-domain rapid scanning optical delay line (TD-RSOD) suitable for optical coherence tomography (OCT) is presented. The 6 dB power efficiency of this TD-RSOD over conventional double-pass Fourier-domain RSOD (FD-RSOD) provides approximately 4 dB SNR advantage in a typical balanced-detection OCT. The scanning performance of TD-RSOD is comparable to that of FD-RSOD.     

工程防水有关问题的思索

探讨了"防水"、"防水材料"、"工程防水"、"防水工程"的定义及相互关系;分析指出应当加强刚性防水的研究,加强工程防水标准规范及相关管理工作;最后从工程发展的整体角度展望了工程防水技术的发展.     

一种可起到值班火焰作用的介质阻挡放电装置

为了增强燃烧的稳定性,提出了利用介质阻挡放电等离子体装置来实现值班火焰的思路。通过布置在燃烧器出口扩张段上的等离子体激励器产生等离子体,并在燃烧过程中一直保持等离子体激励器处于工作状态,这样产生的等离子体可以起到类似值班火焰的作用——稳定燃烧、防止熄火。该装置具有结构简单紧凑、功耗低、激励参数可以在线调节且不影响燃烧器结构设计等优点。基于实验研究考察了该装置对旋流扩散燃烧中不稳定抬升火焰的作用效果。火焰结构的观测通过平面激光诱导荧光测试系统来实现。实验中观测到随等离子体激励功率增大,火焰高度逐步降低向喷嘴出口位置靠近,且反应更趋紧凑,这初步验证了该装置可以稳定燃烧、防止熄火,表明通过介质阻挡放电等离子体装置来实现值班火焰的设计思路可行。     

一种应用于电力系统的锁相环

随着电力系统的快速发展,电力系统信号分析越来越重要。本文结合电能质量检测、电力变换以及电力系统保护等方面的实际需求,设计分析了一种改进型锁相环(IPLL)。文中利用控制理论详细分析了IPLL的数学模型,基于Matlab/Simulink对IPLL的功能进行了仿真。上述分析表明,该结构可以满足提取电网信号的相位、频率、幅值和基波等信息的需求。与电力系统中普遍应用的锁相环相比,减少了??变换和dq变换等环节,增加了跟踪信号幅值的功能。为电力系统的信号分析提供了一种新思路。     

电力通信网运行方式管理通用图元库

图元是组成图形的基本元素,图形化信息的显示、用户的操作大多通过图元完成.为实现电力通信网运行方式图的信息化、标准化绘制,图形化、智能化管理,文章基于面向对象的思想,采用ActionScript语言建立通用图元库.阐述了图元基类和各级子类的层次结构,给出了图元类中属性的设计方法及操作的具体实现,并将图元信息存入关系数据库,实现了标准化、开放式的运行方式图元库,为图形管理平台提供了易用、便于扩展的数据接口.     

Design and Performance of an Ultra-Narrowband Superconducting Filter at UHF Band

A stepped impedance spiral resonator suitable for high-temperature superconducting (HTS) filter with bandwidth narrower than 0.5% is presented. An eight-pole demonstration HTS filter is developed with a central frequency of 650 MHz and a bandwidth of 0.3%. The measurements show that the insertion loss is less than 0.3 dB, and the return loss is better than 16 dB. The filter has out-of-band rejections of 65 dB at 2 MHz below the passband and 80 dB at 2 MHz above the passband, respectively.     

Chitosan-catalyzed n-butyraldehyde self-condensation reaction mechanism and kinetics

The chitosan was found to possess an excellent catalytic performance in n-butyraldehyde selfcondensation to 2E2H. Under suitable conditions, the conversion of n-butyraldehyde, the yield and selectivity of 2E2H separately attained 96.0%, 86.0% and 89.6%. The chitosan catalyst could be recovered and used for 5 times without a significant deactivation after being treated with ammonium hydroxide. In order to elucidate the reaction mechanism, the adsorption and desorption of n-butyraldehyde on the surface of chitosan were studied using in situ FT-IR spectroscopy analysis. The result showed that n-butyraldehyde interacts with-NH₂ group of chitosan to form an intermediate species with an enamine structure. Then the reaction process of n-butyraldehyde self-condensation was monitored by React-IR technique and it was found that n-butyraldehyde self-condensation to 2-ethyl-3-hydroxyhexanal followed by a dehydration reaction to 2-ethyl-2-hexenal. On this basis, chitosan-catalyzed n-butyraldehyde self-condensation reaction mechanism was speculated and its reaction kinetics was investigated. The self-condensation reaction follows auto-catalytic reaction characteristics and then the corresponding kinetic model was established.     

ZSM-5/MgO质量比对复合催化剂物化性质及合成甲硫醇反应的影响

采用介孔碱性MgO对微孔酸性ZSM-5分子筛进行复合改性,利用液相沉淀包覆技术制备了ZSM-5/MgO复合催化剂,研究了ZSM-5与MgO质量比对复合催化剂物化性质和合成甲硫醇催化性能的影响。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、比表面积及孔隙分析仪(BET)和化学吸附分析仪(CO₂/NH₃-TPD)等手段对不同复合催化剂的晶相组成、微观形貌、孔结构及表面酸碱性进行分析表征。结果表明：ZSM-5/MgO质量比对ZSM-5/MgO复合催化剂的物化性质和催化性能影响较大。过高或过低ZSM-5/MgO质量比制得复合催化剂中MgO结晶度都有所降低,且未形成包覆相结构;ZSM-5/MgO质量比为1/3时制得复合催化剂形成了均匀包覆相结构和微 介孔结构(总比表面积为162 m²/g,总孔体积0.46 cm³/g),同时具有酸碱特性;在反应压力1.0 MPa、反应温度370  ℃、H2S/CH₃OH摩尔比2/1、N₂流速80 mL/min、H₂S流速4.9 mL/min反应条件下合成甲硫醇,复合催化剂表现出优越的催化性能、稳定性及寿命,CH₃OH转化率、CH₃SH选择性和CH₃SH收率分别达到90.48%、90.04%和81.47%,催化剂寿命达到18 h。与单一ZSM-5分子筛相比,复合催化剂寿命延长了7 h,CH₃SH收率提高了13.97百分点。     

Dilated and soft attention-guided convolutional neural network for breast cancer histology images classification

Breast cancer is one of the most common types of cancer in women, and histopathological imaging is considered the gold standard for its diagnosis. However, the great complexity of histopathological images and the considerable workload make this work extremely time-consuming, and the results may be affected by the subjectivity of the pathologist. Therefore, the development of an accurate, automated method for analysis of histopathological images is critical to this field. In this article, we propose a deep learning method guided by the attention mechanism for fast and effective classification of haematoxylin and eosin-stained breast biopsy images. First, this method takes advantage of DenseNet and uses the feature map's information. Second, we introduce dilated convolution to produce a larger receptive field. Finally, spatial attention and channel attention are used to guide the extraction of the most useful visual features. With the use of fivefold cross-validation, the best model obtained an accuracy of 96.47% on the BACH2018 dataset. We also evaluated our method on other datasets, and the experimental results demonstrated that our model has reliable performance. This study indicates that our histopathological image classifier with a soft attention-guided deep learning model for breast cancer shows significantly better results than the latest methods. It has great potential as an effective tool for automatic evaluation of digital histopathological microscopic images for computer-aided diagnosis.     

稀土与热处理对高碳铬铸钢碳化物的形态及冲击韧性的影响

研究了稀土与热处理对高碳铬铸钢碳化物的形态及冲击韧性的影响。结果表明，稀土和热处理均能改善高碳铬碳钢碳化物的形态与分布，提高其冲击韧性，尤其稀土与热处理共同作用时，效果更显。