电子信息产品环境适应性标准的现状及需求

环境适应性是电子信息产品重要的质量属性之一。通过对环境适应性技术及其标准发展的概况阐述,介绍了国内外电子信息产品环境适应性领域标准的现状和现有标准的需求情况。     

超级电容器容量特性的试验研究

通过两阶段充电时间序列设计与试验研究,分析充电电流分别与碳基超级电容器的实际电容量、有效储能量和充电效率之间的定量拟合关系。在室温条件下,实际电容量与充电电流的定量关系比较符合指数函数描述,拟合曲线的相关系数均大于0.99;标称电容量为0.5MF的碳基超级电容器在充电电流小于220A的条件下保持着较高的储能水平,但当充电电流超过220A,该超级电容器的总有效储能量急剧衰减,这表明超级电容器的最佳储能水平受充电参数优化范围的制约。     

生产工艺对NTC热敏电阻粉料可重复性的影响

NTC粉料的可重复性,取决于粉料加工结果的可重现性和稳定性。故从控制粉料球磨粒度和球磨均匀性的角度,对粉料加工过程中的关键工序进行改良和精确控制,实施主料–掺杂–主料的配料次序,采用圆球状锆质磨介,并根据材料体系区分不同的预烧温度,采用(或者接近)临界球磨速度磨料等一系列改良措施,从而获得(1.0±0.2)μm的可控粒度范围粉料,达到粉料具有良好可重复性的目的。     

低温共烧陶瓷用硼硅酸盐玻璃的研究进展

概述了低温共烧玻璃陶瓷复合材料体系中所采用的硼硅酸盐玻璃的组成、工艺、应用技术参数。比较了锌、铅、钡硼硅酸盐玻璃组成、掺杂量对玻璃陶瓷的烧结特性的影响。指出了不同硼硅酸盐玻璃材料的优缺点和在低温共烧陶瓷技术中的适用范围。     

Metal ion capacitor composed of the thin-walled surfaces enabling high-rate performance and long cycling stability

Electrochemical capacitors (referred to as supercapacitors) have high power density, long cycling stability, and are eco-friendly for use in electronic applications. The proper and stable utilization of supercapacitor systems can expand the practical scope of energy-powering applications in various device platforms. Nevertheless, the low energy density of conventional oxide and sulfide electrode materials still limits the practical realization of supercapacitor devices in real electronic applications. This limitation results from the poor surface stability, structural collapse, and low electrical conductivity of the oxide and sulfide materials. Single metal electrodes with multivalent metal ions exhibit promising energy-storing kinetics and may be viable alternatives to these oxide and sulfide electrode materials. Here, we report a metal zinc (Zn) electrode supercapacitor (ZIC) consisting of a thin-walled architecture as an electrode by means of a voltage-controlled electroplating method. The optimized ZIC exhibited excellent pseudo-capacitive performance, excellent high-rate performance, and an outstanding cycling stability.     

Machine Learning Algorithm to Predict Acidemia Using Electronic Fetal Monitoring Recording Parameters

Background: Electronic fetal monitoring (EFM) is the universal method for the surveillance of fetal well-being in intrapartum. Our objective was to predict acidemia from fetal heart signal features using machine learning algorithms. Methods: A case–control 1:2 study was carried out compromising 378 infants, born in the Miguel Servet University Hospital, Spain. Neonatal acidemia was defined as pH < 7.10. Using EFM recording logistic regression, random forest and neural networks models were built to predict acidemia. Validation of models was performed by means of discrimination, calibration, and clinical utility. Results: Best performance was attained using a random forest model built with 100 trees. The discrimination ability was good, with an area under the Receiver Operating Characteristic curve (AUC) of 0.865. The calibration showed a slight overestimation of acidemia occurrence for probabilities above 0.4. The clinical utility showed that for 33% cutoff point, missing 5% of acidotic cases, 46% of unnecessary cesarean sections could be prevented. Logistic regression and neural networks showed similar discrimination ability but with worse calibration and clinical utility. Conclusions: The combination of the variables extracted from EFM recording provided a predictive model of acidemia that showed good accuracy and provides a practical tool to prevent unnecessary cesarean sections.     

虚拟电子实验台与电路设计的实验教学研究

介绍了EWB的基本概念和特点,结合EWB在电子技术实验中的应用实例,体现了EWB在实验教学中具有明显的优势.     

NaxCoO2·yH2O体系的高分辨电子能量损失谱和电子结构研究

本文通过高分辨电子能量损失谱(EELS)的实验分析与密度泛函计算相结合的方法,研究了NaxCoO2·yH2O系统的电子结构特性和电子关联效应.实验结果表明,金属性Na0.3CoO2材料和电荷有序绝缘体Na0.5CoO2的O-K吸收边存在明显的结构差别,在Na0.5CoO2的EELS中第一个峰发生明显分裂,密度泛函计算证实这种分裂现象和电子关联效应直接相关.通过理论模拟谱线与实验谱线的比较确定了其电子关联强度为U=3.0 eV.在Na0.3CoO2·yH2O(y=0,0.6,1.3)超导体系中,实验发现其能损谱的低能部分随着水含量的增加发生系统的变化,损失峰向低能量方向逐步移动.电子结构计算表明水分子的插入可以引起费米面附近能态原子轨道杂化情况的改变,从而导致EELS的变化.     

共形天线的发展及其电子战应用

介绍了共形天线的基本概念和特征,总结了当前共形天线阵列的最新发展,分析了共形天线在电子战中的应用前景.     

NO在稀有金属钇表面的吸附行为

以往的理论在预测六方结构(HCP)金属的表面能时,计算值与实验值存在较大误差.鉴于此,本文首先用一种较为合理的方法精准地预测了稀有金属钇(Y)(0001)面的表面能,计算值(1.141 J/M²)与实验值(1.125 J/M²)吻合的很好.随后,系统研究了NO小分子在Y(0001)面不同位置(空位、桥位和端位)的吸附行为.结果表明:空位(H1)表现出了良好的吸附能力,吸附能超过了5eV,同时N-O键长伸长量超过了24%,此时,NO分子几乎平行地吸附于Y(0001)表面.所有的吸附位置的N-O分子伸长量范围为0.2?-0.42?.这种伸长量明显超过了NO在其它金属表面时的计算结果.