A Deep Learning-Based Continuous Blood Pressure Measurement by Dual Photoplethysmography Signals

This study proposed a measurement platform for continuous blood pressure estimation based on dual photoplethysmography (PPG) sensors and a deep learning (DL) that can be used for continuous and rapid measurement of blood pressure and analysis of cardiovascular-related indicators. The proposed platform measured the signal changes in PPG and converted them into physiological indicators, such as pulse transit time (PTT), pulse wave velocity (PWV), perfusion index (PI) and heart rate (HR); these indicators were then fed into the DL to calculate blood pressure. The hardware of the experiment comprised 2 PPG components (i.e., Raspberry Pi 3 Model B and analog-to-digital converter [MCP3008]), which were connected using a serial peripheral interface. The DL algorithm converted the stable dual PPG signals acquired from the strictly standardized experimental process into various physiological indicators as input parameters and finally obtained the systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP). To increase the robustness of the DL model, this study input data of 100 Asian participants into the training database, including those with and without cardiovascular disease, each with a proportion of approximately 50%. The experimental results revealed that the mean absolute error and standard deviation of SBP was 0.17 ± 0.46 mmHg. The mean absolute error and standard deviation of DBP was 0.27 ± 0.52 mmHg. The mean absolute error and standard deviation of MAP was 0.16 ± 0.40 mmHg.     

基于小波变换的轮轨垂向力信号降噪

轮轨力应变信号在采集过程中,由于噪声干扰的存在,将严重影响所采集数据的准确性。针对轮轨力应变信号中存在的基线漂移和随机白噪声,提出基于小波变换的去噪方法:采用db 6小波基,根据小波多分辨率分析理论,以大尺度分解的逼近分量估计基线漂移成分,从而消除基线漂移;对于随机白噪声则是运用小波阈值去噪法,先根据离散有限序列的自相关函数确定小波分解的最优分解层数,然后采用最小最大阈值以及硬阈值函数,从而实现对白噪声的滤除。仿真与实测数据分析都表明该去噪法能达到比较理想的效果。     

Dynamics of a Dual Power-split Transmission Based on Loaded Tooth Contact Analysis

In order to implement the dynamic characteristic of a dual power-split transmission,a dynamic mechanics model is built. Firstly,according to the method of theoretical analysis of the tooth contact analysis ( TCA) and loaded tooth contact analysis ( LTCA) ,the actual meshing process of each gear pairs is simulated, and the time-varying mesh stiffness excitations are obtained,which can improve the numerical precision. Secondly,by using the lumped mass method,the bending-torsional coupling three dimensional dynamic model of the dual power-split transmission is established,and the identical dimensionless equations are deduced by eliminating the effect of rigid displacement and the method of dimensional normalization. Finally,by the method of the fourth order Runge-Kutta algorithm with variable step lengths,the responses of this system in a frequency domain and time domain are obtained,and the dynamic load change characteristics of each gear pairs are analyzed. The results show that the establishment,solution and analysis of the system dynamics model could provide a basis for the dynamic design,and have an important significance for the dynamic efficiency analysis and dynamic performance optimization design of the dual power-split transmission.     

Modeling Ultrasonic Pulse-Echo Signals from a Flat-Bottom Hole in Immersion Testing Using a Multi-Gaussian Beam

This paper proposes an ultrasonic measurement model that can predict the pulse-echo signals from a flat-bottom hole in an isotropic, homogeneous solid specimen immersed in water in a computationally efficient manner. To develop such a model, a measurement model approach is adopted based on two important assumptions: the paraxial approximation for the transducer beam and the small flaw assumption for the flat-bottom hole. The modular model that results from these two assumptions contains three terms: a diffraction correction term, a far-field scattering amplitude term and a system efficiency factor term. The diffraction correction is defined based on a multi-Gaussian beam model which allows the rapid evaluation of the wave field incident on the hole. The far-field scattering amplitude of the flat-bottom hole is obtained using the Kirchhoff approximation together with the small flaw assumption. The system efficiency factor is determined by deconvolution of an experimental front surface reflection signal by a reference reflector model. Here, the contribution of each of these three terms to the overall measurement model are described in detail and the accuracy of the proposed model is verified by the comparison of the model-based predictions to experiments.     

胶晶/嵌段共聚物双重模板制备多级孔材料

采用分段乳液聚合法和无皂乳液聚合法制备了聚苯乙烯(PS)微球,以此单分散胶态晶体和嵌段共聚物P123为模板剂,通过Y型分子筛前驱体的填充和模板剂的去除制备了具有大-介-微多级孔的材料.采用XRD、SEM和TEM等手段表征了PS微球及多级孔材料.结果表明,分段乳液聚合可以制备平均粒径为50nm的PS微球,无皂乳液聚合可以制备450nm左右的PS微球;以其作为大孔模板剂分别考察了PS微球粒径、模板剂用量、水用量等因素对多级孔材料合成的影响,结果表明,PS微球的粒径越大,材料中大孔的分散性越好.合成多级孔材料的条件为:PS微球乳液与前驱体的比值(质量比)为1.0~0.5,水与前驱体的比值为7.5,P123与前驱体的比值为0.1.     

非连续接触下滚圈的接触压力及疲劳寿命预测

建立了非连续接触下筒体-滚圈接触压力的计算模型，得出了滚圈弯矩及弯曲应力计算公式。应用名义应力法和局部应力应变法，建立了滚圈疲劳寿命预测模型。通过实例分析，得出了如下结论：通过调窑，将滚圈的最大支承载荷控制在2500kN以内，能显著提高滚圈的疲劳寿命；在传统设计中，将滚圈支承角定为30°不合理；存在一个最佳滚圈支承角，此时滚圈疲劳寿命最大。     

双向晶闸管调光电路

宾馆及民居内的灯光 ,根据不同的需求 ,可以选择不同的调光电路。文章力图将花样繁多的调光电路分类 ,并介绍各类调光电路的用途及优缺点。     

微孔光纤测头的研制及应用

基于微孔测量中测头不能做得足够小的技术难题,文中提出采用标准多模通信光纤,按特定的工艺技术方法烧熔光纤测球,再进行封装制成测头,应用在微孔测量中。通过对研制成的6φ．1mm光纤测头几何形貌进行实际测量,并应用于φ0．6mm左右小孔孔径的测量分析,标准偏差不超过0．5μm,取得了很好的应用效果。     

First-Principles Prediction of Superconductivity in Hole Doping of MgCN2

Journal of Superconductivity and Novel Magnetism - Hydrogen-based, boron-based, and carbon-based compounds have been the focus of previous investigations in the process of searching for...     

用于微球球度测量的双SPM测头对准系统

压电微音叉与钨探针结合,构成SPM(扫描探针显微镜)的扫描测头。将双测头对称置于微球的赤道圆截面处,构成微球球度差动测量系统。通过视觉引导系统对双测头进行粗对准,用视频显微镜对微球和测头分别聚焦,拍摄多组照片,然后对对准图像进行小波分析边缘检测及多图像融合处理,再将图像处理结果反馈到系统进行精确对准。在实际实验中,获得了该对准方法下微球赤道圆截面的测量结果,并分析了对准误差对系统测量结果带来的影响。     

Time Domain Analysis of Optical Fiber Probe Signals Measured in a Short Circulating Fluidized Bed Riser

A time domain analysis of electrical signals provided by an optical fiber probe was conducted in order to characterize the local flow dynamics of a short circulating fluidized bed riser with a height of 2.42 m and ID of 82 mm. Experiments were carried out with air, and the bed materials were FCC particles (Geldart A). Probability and standard deviation distribution of signals measured locally at five radial positions and four axial positions are presented. The probability distribution can indicate the uniformity of the flow in terms of solids holdup distribution and can reveal the formation of clusters. Probability distributions indicate that the flux is more uniform in the core region of the reactor and that clusters appear near the wall. The highest value obtained in the standard deviation of the radial distribution suggests greater interaction between particles at that radial position. It was found that for the two lower axial positions, this phenomenon occurs near the wall, and for the two higher positions, the interactions between particles occur both near the wall and in the center due to the exit configuration of the reactor.     

Syntax-Based Aspect Sentiment Quad Prediction by Dual Modules Neural Network for Chinese Comments

Aspect-Based Sentiment Analysis (ABSA) is one of the essential research in the field of Natural Language Processing (NLP), of which Aspect Sentiment Quad Prediction (ASQP) is a novel and complete subtask. ASQP aims to accurately recognize the sentiment quad in the target sentence, which includes the aspect term, the aspect category, the corresponding opinion term, and the sentiment polarity of opinion. Nevertheless, existing approaches lack knowledge of the sentence’s syntax, so despite recent innovations in ASQP, it is poor for complex cyber comment processing. Also, most research has focused on processing English text, and ASQP for Chinese text is almost non-existent. Chinese usage is more casual than English, and individual characters contain more information. We propose a novel syntactically enhanced neural network framework inspired by syntax knowledge enhancement strategies in other NLP studies. In this framework, part of speech (POS) and dependency trees are input to the model as auxiliary information to strengthen its cognition of Chinese text structure. Besides, we design a relation extraction module, which provides a bridge for the overall extraction of the framework. A comparison of the designed experiments reveals that our proposed strategy outperforms the previous studies on the key metric F1. Further experiments demonstrate that the auxiliary information added to the framework improves the final performance in different ways.     

微孔光纤测头的研制及应用

基于微孔测量中测头不能做得足够小的技术难题,文中提出采用标准多模通信光纤,按特定的工艺技术方法烧熔光纤测球,再进行封装制成测头,应用在微孔测量中.重点介绍了这种测头的技术参数和成形方法、原理,并对研制的φ0.1 mm光纤测头几何形貌进行实际测量,应用于φ0.6 mm小孔孔径的测量分析,标准偏差不超过0.5μm,取得了很好应用效果.     

国外舰船声特征信号预测软件简介

舰船声特征信号的预测和评价是当前国内外的前沿课题,也是迫切需要发展的研究领域。迄今推广运用了国外的三种软件：辐射噪声估算软件--NDES、声目标强度估算软件--ARTES、综合辐射噪声与自噪声建模软件--FNVNOISE。以上方法将声特征信号预测建立在理论计算基础上,对于复杂问题均建立了各种专门用来帮助设计人员进行重要计算的数据库。研究人员可通过不断增加和核对新的数据,使数据库和计算方法得到不断改进和完善,从而为将来在解决设计中遇到的问题提供更有效的支持。     

高精度双测头量块比较仪的研究

研制了一种新型高精度量块比较仪,该比较仪采用上、下双电感测头进行测量.给出了比较仪的总体结构,系统采用数字滤波算法对电感测微仪的随机误差进行处理,在±20μm测量量程内,对比较仪进行了精确标定,编制了测量控制软件.并对该量块比较仪进行了重复性和示值误差测试.实验结果表明其示值误差δ≤±(0.02+0.002L)μm.     

浅谈逐孔起爆技术时间间隔的选取

叙述了逐孔起爆技术机理和优越性,对选取微差间隔时间影响因素进行了分析,推荐了间隔时间的理论计算和经验选取的方法以及国内部分应用单位的实际数据,并对雷管延期精度和窜段问题的原因给予了解析,提出了解决办法的建议.     

利用微机进行振动信号的采集和处理

本文介绍了一个轴系试验台的振动信号测试系统,该系统的特点是将通用微机与常规振动测试仪器联用,以达到测量系统数字化和一定范围的智能化。文中着重讨论了如何从试验目的出发选配硬件,并运用现代信号分析技术编制软件,以有效地对轴系振动信号进行采集和处理。     

混凝土中瞬时爆炸波测试技术及分离的实验研究

为稳定测量混凝土中炮孔周围的爆炸波,对应变片和超动态应变测试系统的频响及最优匹配开展了系统研究,得到了应变片相对误差δ与其允许最高频率fmax之间的关系,测试系统的阶跃信号响应上升时间为0.3μs。基于一维应力波原理,提出了用SHPB技术中透射杆上的应力动态标定试件上输出电压的新方法,得到了爆炸冲击波作用下测试系统的频响和时频分布。针对爆炸波微信号传输中的易受干扰问题,采用了电磁屏蔽等抗干扰技术。用该系统对混凝土模型开展了不耦合装药爆炸波测试,成功测得了23μs内在爆炸近中区激起的爆炸波。通过Rihaczek分布,将爆炸波分离为[(2.3～4.5μs),(0～829 kHz)]的爆炸冲击波区、[(4.5～7.2μs),(0～743 kHz)]的应力波区及[(7.2～24.7μs),(0～514 kHz)]的爆生气体膨胀作用区,并就分离各区作用过程做了分析。