A polarization-independent and broadband microwave metamaterial absorber based on three-dimensional structure

In this paper, we design a polarization-independent and broadband microwave metamaterial absorber (MMA) based on three-dimensional structure. The simulated results show that the proposed absorber has a broad absorptance band from 60.4 to 100.0 GHz with the absorptance efficiency over 90%. The effective medium theory (EMT), electric field, surface current and power loss density distributions are adopted to explain the physical mechanism of the perfect absorptance. In addition, the absorptance differences can be observed between transverse electric (TE) wave and transverse magnetic (TM) wave at oblique incidence. The proposed absorber can be utilized in many applications such as perfect absorbers and radomes.     

EAK基熔铸分子间炸药的熔化安全性

实验测定了不同装药尺寸的含RDX的EAK (乙二胺二硝酸盐 ,硝酸铵 ,硝酸钾三元低共熔物 )基分子间炸药的热爆炸临界温度 ,比较了Semenov、Thomas和Frank Kamenetskii临界方程对实验临界温度的处理结果 ,并由此得到了该炸药的分解动力学参数 :Arrhenius活化能为 1 5 8 2kJ·mol- 1,指前因子为 1 .4 6× 1 0 13s- 1.以分解动力学参数为主要依据 ,通过热爆炸理论推算了该炸药在熔化工艺过程中的热爆炸危险性 ,结果表明该炸药在 1 30℃以下 ,尺寸小于 2m的设备中进行工艺操作是安全的     

In silico discovery of significant pathways in colorectal cancer metastasis using a two‐stage optimisation approach

Accurate and reliable modelling of protein–protein interaction networks for complex diseases such as colorectal cancer can help better understand mechanism of diseases and potentially discover new drugs. Different machine learning methods such as empirical mode decomposition combined with least square support vector machine, and discrete Fourier transform have been widely utilised as a classifier and for automatic discovery of biomarkers for the diagnosis of the disease. The existing methods are, however, less efficient as they tend to ignore interaction with the classifier. In this study, the authors propose a two‐stage optimisation approach to effectively select biomarkers and discover interactions among them. At the first stage, particle swarm optimisation (PSO) and differential evolution (DE) are used to optimise parameters of support vector machine recursive feature elimination algorithm, and dynamic Bayesian network is then used to predict temporal relationship between biomarkers across two time points. Results show that 18 and 25 biomarkers selected by PSO and DE‐based approach, respectively, yields the same accuracy of 97.3% and F1‐score of 97.7 and 97.6%, respectively. The stratified analysis reveals that Alpha‐2‐HS‐glycoprotein was a dominant hub gene with multiple interactions to other genes including Fibrinogen alpha chain, which is also a potential biomarker for colorectal cancer.Inspec keywords: cancer, proteins, particle swarm optimisation, evolutionary computation, support vector machines, recursive functions, Bayes methods, genetics, molecular biophysics, medical computingOther keywords: colorectal cancer metastasis, two‐stage optimisation approach, protein–protein interaction networks, biomarkers, particle swarm optimisation, differential evolution, support vector machine recursive feature elimination, dynamic Bayesian network, stratified analysis, Alpha‐2‐HS‐glycoprotein, hub gene, Fibrinogen alpha chain     

Cr：Mg2SiO4晶体红外光致发光谱的研究

报道了在室温和液氮温度下分别用1064nm和532nm激光诱导的Cr:Mg_2SiO_4晶体的红外光致发光谱,并详细分析光谱的结构和特点.在假设Cr:Mg_2SiO_4晶体中同时存在(CrO_6)~(9-)和(CrO_4)~(4-)两种络离子的基础上讨论了红外光致发光的产生机理,理论计算证明假设是合理的.     

精密数显转台研制

光电传感和精密刻划技术 ,是开发精密数显转台的主要技术基础。本文详细介绍基本原理、结构要求、功能特点、工艺试验和精度测试等。样机系列表明 ,其精度和性能基本达到和部分指标超过 (国家 )部颁一级精度的标准。     

基于离散元方法的RDX-Al颗粒混合数值模拟分析

基于离散元方法,以旋转筒内RDX-Al二元颗粒体系的搅拌过程为研究对象进行模拟。采用离散元软件(EDEM),首先研究RDX-Al二元颗粒各自随转速的变化趋势,并进一步得出二元颗粒变化率的特点,做出分布上的拟合,得出最吻合模拟试验的函数为指数函数。然后,将旋转筒细分为多个单元空间,考察旋转轴与单元空间之间的距离对二元颗粒混合效果的影响。结果表明:单元空间离旋转轴越远,即旋转半径越大,颗粒之间的变化率也就越快,越容易达到均匀状态。最后,考察加入抄板的影响,结果表明:RDX-Al二元颗粒趋于的稳定值分别发生了改变。     

基于机器阅读理解的中文命名实体识别方法

针对现有命名实体识别方法主要考虑单个句子内的上下文信息,很少考虑文档级上下文影响的问题,文中提出基于机器阅读理解的中文命名实体识别方法,利用阅读理解思想,充分挖掘文档级的上下文特征,支撑实体识别.首先,针对每类实体,将实体识别任务转化为问答任务,构建问题、文本及实体答案三元组.然后,将三元组信息通过双向Transformer编码器进行预训练,再通过卷积神经网络捕捉文档级文本上下文信息.最后通过二进制分类器实现实体答案预测.在MSRA、人民日报公开数据集和自建数据集上的命名实体识别对比实验表明,文中方法性能较优,阅读理解思想对实体识别具有较好的作用.     

波导小室标准场装置研究

本文对作者正在研制的波导小室标准场装置作了详细的理论分析，包括其工作原理、设计方法及误差分析。当波导小室设计合理、匹配良好时，波导小室中传输行波，产生“准静态场”，可用作高频标准场，进行近场测试仪的校准，校准精度为±１ｄＢ。     

高频电场标准装置的研制

本文介绍新近研制成功的高频电场标准装置。该装置采用标准电场法原理，由１３副工作频率各异的半波谐振偶极子天线作标准发射天线，覆盖频率范围３０￣１０００ＭＨｚ，在长４０ｍ、宽１２．５ｍ的钢质开阔试验场上，发射场强１００￣１２０ｄＢμＶ／ｍ，不确定度优于１ｄＢ，目前已用于场强量值传递和天线校准等电磁兼容试验。     

Nd：MgO：LiNbO_3光波导的特性

用质子交换法制备了Ｎｄ：ＭｇＯ：ＬｉＮｂＯ３波导。通过测量平面波导的二次离子质谱，得到了波导的原子组分分布，并测量了Ｎｄ：ＭｇＯ：ＬｉＮｂＯ３晶体的吸收谱线，最后利用端面耦合，分别得到了条波导内和衬底内激光诱导的荧光谱线。