Integrated power electronics module based on chip scale packaged power devices

High performance can be obtained for the integrated power electronics module（IPEM） by using a three-dimensional packaging structure instead of a planar structure. A three- dimensional packaged half bridge-IPEM （HB-IPEM）, consisting of two chip scale packaged MOSFETs and the corresponding gate driver and protection circuits, is fabricated at the laboratory. The reliability of the IPEM is controlled from the shape design of solder joints and the control of assembly process parameters. The parasitic parameters are extracted using Agilent 4395A impedance analyzer for building the parasitic parameter model of the HB- IPEM. A 12 V/3 A output synchronous rectifier Buck converter using the HB-IPEM is built to test the electrical performance of the HB-IPEM. Low voltage spikes on two MOSFETs illustrate that the three-dimensional package of the HB-IPEM can decrease parasitic inductance. Temperature distribution simulation results of the HB-IPEM using FLOTHERM are given. Heat dissipation of the solder joints makes the peak junction temperature of the chip drop obviously. The package realizes three-dimensional heat dissipation and has better thermal management.

Constructing Large Scale Cohort for Clinical Study on Heart Failure with Electronic Health Record in Regional Healthcare Platform:Challenges and Strategies in Data Reuse

Regional healthcare platforms collect clinical data from hospitals in specific areas for the purpose of healthcare management.It is a common requirement to reuse the data for clinical research.However,we have to face challenges like the inconsistence of terminology in electronic health records (EHR) and the complexities in data quality and data formats in regional healthcare platform.In this paper,we propose methodology and process on constructing large scale cohorts which forms the basis of causality and comparative effectiveness relationship in epidemiology.We firstly constructed a Chinese terminology knowledge graph to deal with the diversity of vocabularies on regional platform.Secondly,we built special disease case repositories (i.e.,heart failure repository) that utilize the graph to search the related patients and to normalize the data.Based on the requirements of the clinical research which aimed to explore the effectiveness of taking statin on 180-days readmission in patients with heart failure,we built a large-scale retrospective cohort with 29647 cases of heart failure patients from the heart failure repository.After the propensity score matching,the study group (n=6346) and the control group (n=6346) with parallel clinical characteristics were acquired.Logistic regression analysis showed that taking statins had a negative correlation with 180-days readmission in heart failure patients.This paper presents the workflow and application example of big data mining based on regional EHR data.

Electronic Cigarette Use Scale: Development and evaluation of a measure among Chinese students

Objective:To develop the Electronic Cigarette Use Scale(ECUS)based on social cognitive theory and test its reliability and validity,so as to provide a scientific tool for evaluating the use of e-cigarette smokers in China.Methods:Based on the review of social cognitive theory and literature analysis,the item pool of ECUS was constructed to form the initial version.From January to March in 2022,using the convenient sampling method,electronic questionnaires were distributed to college students in Guangdong Province through the questionnaire star platform,and a total of 1047 valid questionnaires were collected for item screening.The total sample was randomly divided into sample 1(n=517)and sample 2(n=530)for Exploratory Factor Analysis(EFA)and Confirmatory Factor Analysis(CFA)respectively to further test the reliability and validity of the scale and finally form a 24-item scale.Results:The formal ECUS included 24 items,6 factors were extracted by EFA,and the cumulative explanatory variance was 72.774%.CFA showed that the goodness-of-fit indices were acceptable:χ^(2)/df=2.61,CFI=0.938,TLI=0.928,RMSEA=0.055,90%CI(0.050,0.061),SRMR=0.046,AIC=34694.405,BIC=35036.235.The Cronbach’saof the 24-item scale was 0.898,and the Cronbach’saof each dimension was between 0.839 and 0.954.Both convergent validity and discriminant validity reached the standard.Conclusion:The 24-item ECUS developed in this study has been tested with good reliability and validity and is suitable for evaluating the use of e-cigarette smokers in China.

Relativistic Multichannel Theory:Scaling Behavior of Multichannel Quantum Defect Theory Parameters(μ_(α),U_(iα)) Along the Ne-Like Iso-electronic Sequence

The compact physical parameters(μ_(α),U_(iα))in multichannel quantum defect theory(MQDT)can be directly calculated with relativistic multichannel theory(RMCT).Here we report a systematic study of the MQDT parameters(fiay Uia)with RMCT along the Ne-like iso-electronic sequence(including Ca^(10+),Fe^(16+),Ge^(22+),Ag^(37+) ions).We find that the physical parameters(μ_(α),U_(iα))show a very interesting scaling behavior along the iso-electronic sequence.

Ultrastructural Findings, at Micrometric and Nanometric Scales, in Rectal and Muscular Mucosa of Patients with HIV/AIDS and Anorectal Pathology

Objective: To determine the ultrastructural findings on Rectal Mucosa (RM) of patients with HIV/AIDS and anorectal pathologies (ARP), at micrometric and nanometric scales. Materials and methods: 5 patients were evaluated, 18 - 55 years old, with ARP (HIV co-infection with HPV, n = 4, and HIV-negative patient with HPV infection) (control n = 1), who were referred to the Coloproctology Unit of the HUC, and subjected to rectoscopy and biopsy. RM samples were identified, placed in a sterile plastic bottle with 1 mL of 2% glutaraldehyde and immediately transported for routine processing of fine cut (60 - 90 nm) to be evaluated via Transmission Electron Microscopy (TEM). They were fixed with Karnovsky solution with Millonig phosphate buffer (pH 7.4 and 320 mOsm) and post-fixed with OsO4 under the same conditions of pH and osmolarity. Results: Ultrastructural findings, at 10−6 scale: 1) Intestinal mucosa: vacuoles of mucus of different sizes that seem to be fused. 2) Smooth muscle cells: loss of definition of contractile myofilaments mass. 3) Unmyelinated axons and terminals of Schwann cells (SC): Edema and loss of their plasma membranes in some areas of association with axon terminals as well as abundant collagen fibers associated with SC. Ultrastructural findings, at 10−9 scale: 1) Smooth muscle cells: folded wrapper cores and edema of mitochondria and rough endoplasmic reticulum cisterns (RER). 2) Myelinated axon terminals: Loss of synaptic vesicles. 3) Fibroblasts: One observes mitochondria and cisterns of RER with alterations. All these alterations can generate intestinal and anorectal dysfunction in these patients. Conclusions: The HIV causes changes in rectal and muscular mucosa despite HAART treatment with undetectable viral load.

Recent advances on thermal analysis of stretchable electronics

Stretchable electronics, which offers the performance of conventional wafer-based devices and mechan- ical properties of a rubber band, enables many novel applications that are not possible through conven- tional electronics due to its brittle nature. One effective strategy to realize stretchable electronics is to design the inorganic semiconductor material in a stretchable format on a compliant elastomeric substrate. Engineering thermal management is essential for the development of stretchable electronics to avoid adverse thermal effects on its performance as well as in applications involving human body and biological tissues where even 1-2℃ temperature increase is not allowed. This article reviews the recent advances in thermal management of stretchable inorganic electronics with focuses on the thermal models and their comparisons to experiments and finite element simulations.

Visualization of atomic scale reaction dynamics of supported nanocatalysts during oxidation and ammonia synthesis using in-situ environmental(scanning) transmission electron microscopy

Reaction dynamics in gases at operating temperatures at the atomic level are the basis of heterogeneous gas-solid catalyst reactions and are crucial to the catalyst function.Supported noble metal nanocatalysts such as platinum are of interest in fuel cells and as diesel oxidation catalysts for pollution control,and practical ruthenium nanocatalysts are explored for ammonia synthesis.Graphite and graphitic carbons are of interest as supports for the nanocatalysts.Despite considerable literature on the catalytic processes on graphite and graphitic supports,reaction dynamics of the nanocatalysts on the supports in different reactive gas environments and operating temperatures at the single atom level are not well understood.Here we present real time in-situ observations and analyses of reaction dynamics of Pt in oxidation,and practical Ru nanocatalysts in ammonia synthesis,on graphite and related supports under controlled reaction environments using a novel in-situ environmental(scanning) transmission electron microscope with single atom resolution.By recording snapshots of the reaction dynamics,the behaviour of the catalysts is imaged.The images reveal single metal atoms,clusters of a few atoms on the graphitic supports and the support function.These all play key roles in the mobility,sintering and growth of the catalysts.The experimental findings provide new structural insights into atomic scale reaction dynamics,morphology and stability of the nanocatalysts.

基于物联网技术的鸡智能育种平台研究与应用

为解决鸡规模化生产过程中个体精细化数据采集难度大、成本高、选育配种效率低等问题,研究设计基于物联网的包括适用于鸡全生命周期佩戴的电子标签、自动称重台、移动终端采集系统及鸡智能育种管理系统的鸡智能育种平台。结果显示:该平台实现鸡育雏、育成、产蛋到淘汰各阶段个体外貌、生产性能、调群等数据的精准采集,以及系谱跟踪、报表生成、智能选配等功能;较传统铝质翅标佩戴效率提升40%,个体身份识别正确率超过98%,产蛋、体重、外貌等数据采集准确率超过99%,通过种鸡智能选种选配模型实现了种鸡的快速优选,避免近亲繁殖。研究表明,建立的鸡智能育种平台能满足不同规模养殖企业的生产需求,有效减少人力成本、提升育种效率。

体电子显微学前沿

电子显微成像技术的快速发展使得对完整细胞、组织乃至整个机体进行高分辨三维结构解析研究成为可能,这些可进行大尺度生物样品三维结构研究的电子显微成像技术统称为体电子显微学技术(volume electron microscopy,vEM)。近年来,v EM在研究尺度、分辨率、吞吐量和易用性等方面发展迅速,在整个生命科学领域的应用呈爆炸式增长,该技术因此被《自然》(Nature)评为2023年最值得关注的七项前沿技术之一。然而,vEM相关技术的发展和应用在国内起步较晚,亟待进一步推广。本综述涵盖了vEM的发展历程、技术分类、样品制备、数据收集、图像处理等全方位的内容,便于生命科学、医学等领域研究人员去了解、学习、应用和进一步发展该技术。

计及多重差异的交直流混合多能微网多时间尺度优化调度

近年来,可再生能源发电、热电联产、储能和电力电子变压器(PET)等技术发展迅速,有利于构建多能互补、清洁高效的交直流混合多能微网(MEMG),但不成熟的PET模型和复杂的不确定性为系统的优化调度带来了挑战。为此,首先构建了一种基于三级式PET的交直流混合MEMG结构,建立了包括PET在内的设备模型和不确定性模型;其次,提出了计及多重差异的MEMG多时间尺度优化调度策略,明确了日前-日内-实时三时间尺度调度的协调机制,其中,多重差异包含需求响应资源、系统调度目标和源荷预测精度在时间尺度上的差异,以及不同能量的响应特性差异;再次,建立了对应的多时间尺度优化调度模型,包括日前鲁棒机会约束优化模型、日内随机优化模型和实时分层滚动修正模型,并在日前调度中,改进了传统储能和电热耦合设备的备用模型,设计了基于PET的交直流系统备用共享机制,将调度模型转换为混合整数线性规划模型,给出了利用CPLEX求解器求解多时间尺度调度模型的步骤;最后,通过算例分析表明,所提调度策略可以通过逐级修正调度计划应对不确定性,且所设计备用方案兼具可靠性和灵活性。

基于自然图像模型微调的小鼠脑部电镜图像实例分割

分割模型的准确性和鲁棒性是小鼠脑电镜图像处理中的主要考虑因素。针对电镜图像的技术特点,提出了高度稳健的二维分割算法,准确识别每张切片中各物体的形态结构。本文提出了基于大型自然图像模型的主干网络微调的大尺度二维电镜图像分割模型EM-SAM,用于脑部电镜图像中的实例分割。模型主干网络采用大型自然图像模型SAM中的已训练完成的图像编码器,在电镜图像处理任务中最大化模型提取图像特征的能力。此外,模型采用了U型的解码器设计,并通过小鼠脑电镜图像分割任务进行微调。实验结果表明:在公开数据集SNEMI3D中A-Rand可达到0.054;在公开数据集MitoEM中AP-50和AP-75分别可达到0.883,0.604。EM-SAM在电镜图像神经分割任务中准确性高、鲁棒性强,并且可针对不同任务进行微调。

基于COSMIC掩星观测的顶部电离层标高特征分析

顶部电离层是指F2层电子密度最大值所在高度以上的电离层区域。掩星观测能够提供地面到低轨卫星轨道高度处的整个电离层电子密度剖面,对于顶部电离层的研究具有重要作用。标高是构建顶部以上电离层电子密度剖面模型的重要参数。本文使用2007—2020年的气象、电离层和气候星座观测系统(Constellation Observing System for Meteorology,Ionosphere and Climate,COSMIC)掩星观测数据,提取有效电子密度剖面数据的顶部标高,分析了其随地方时、季节、经纬度和太阳活动水平的变化特性。结果表明:顶部标高具有明显的日变化和季节变化规律,并且表现出强烈的太阳活动依赖性;顶部标高在纬度上的变化强烈依赖于地方时,同时在东西经向上表现出明显的波状结构,且这种经度波状结构在南北半球具有不同的形态;顶部标高在夏季半球具有显著的东西经向差异,南半球夏季更为明显。

多种水等效材料的医用电子束修正因子研究

针对水等效材料在医用电子束剂量测量中修正因子的测量和使用问题,通过扫描医用电子束在水中和水等效材料中的百分深度剂量(percentage depth dose,PDD)曲线,计算获得深度缩放因子c_(pl)、注量缩放因子h_(pl)及总修正因子k_(pl)的实验值。结果表明,通过c_(pl)和h_(pl)组合或仅使用k_(pl)均可将水等效材料测量结果转换为水吸收剂量。比较PDD曲线表明,在10~20 MeV电子能量下3种水等效材料通过c_(pl)-h_(pl)修正后的R_(50),较水中测量最大偏差分别为0.19%、0.28%、0.22%;经k_(pl)修正得到的R_(50),较水中测量最大偏差分别为0.23%、0.29%、0.18%。结论:研究提供了多种材料c_(pl)-h_(pl)、k_(pl)的实验值,可方便用户快速完成电子束水吸收剂量的测量,相比于c_(pl)-h_(pl),使用k_(pl)更加简单高效。

小尺寸金属纳米线力学行为的原位电镜研究进展

金属纳米线在信息采集、存储以及超灵敏传感器等方面被广泛应用。在实际应用中,金属纳米线常处于应力状态下,对关键器件的性能稳定性有直接影响。原位研究金属纳米线在应力作用下的塑性变形原子机制是确保重要元器件在复杂环境下依旧保持稳定的物理性能输出的实验依据。本文介绍了纳米力学原位实验技术的研究进展和纳米材料力学性能曲线的测量策略;在此基础上,从材料的尺寸效应出发,总结了不同直径尺寸金属纳米线的位错、孪晶、表面原子扩散等变形机制与纳米线力学性能之间的相关性;展望了小尺寸金属纳米线原位纳米力学技术和原位实验研究的发展方向。

基于大科学装置的纳米生物效应研究进展

纳米生物效应是指纳米尺度物质与生命体系的相互作用情况。大科学装置也称大科学设施,是指需通过较大规模投入和工程建设来完成、建成后通过长期的稳定运行和持续的科学技术活动而实现重要科学技术目标的大型设施。大科学装置可为纳米生物效应研究提供重要工具。基于大科学装置的相关技术在时间分辨率、空间分辨率、测定通量和原位分析方面具有独特优势,可为纳米生物效应研究提供前沿分析方法。该文介绍了基于大科学装置的相关技术在纳米生物效应研究中的最新进展,着重总结了基于同步辐射装置、自由电子激光装置和中子源等相关技术在纳米生物效应研究中的应用进展,特别是纳米材料表征、纳米材料在生物体内的分布与转化以及纳米材料与生物分子的相互作用研究等。此外,也对利用新一代大科学装置开展纳米生物效应研究进行了展望。

卤化物钙钛矿半导体透射电镜表征的挑战与机遇

卤化物钙钛矿价格低廉,易于合成,具有优异的光电性能,广泛应用于太阳能电池、光电探测器和发光二极管等光电子器件,是当前国际上研究的热点领域,同时入选工信部和国资委评出的首批前沿材料之一。透射电子显微镜表征是揭示卤化物钙钛矿形貌、结构、成分等物理和化学信息的关键。然而,卤化物钙钛矿在电子束辐照下易分解,这种极端敏感性通常会阻碍我们获取钙钛矿本征信息,甚至引起假象。基于此,本文综述了近年来有关卤化物钙钛矿的透射电子显微学研究,重点讨论了卤化物钙钛矿电子束损伤机理、影响钙钛矿电子束敏感性因素、如何降低电子束损伤并获得钙钛矿原子尺度信息。本文旨在引起人们对卤化物钙钛矿电子束敏感性的关注,指导卤化物钙钛矿电子显微学表征,揭示卤化物钙钛矿分解机理,为构建高效稳定的钙钛矿光电器件提供实验指导。

基于电测法的电子秤设计与标定实验

基于电测法的基本原理,结合材料力学中梁弯曲变形的理论知识,通过对静态应变仪参数的标定与校准,将静态应变仪改造成电子秤,从而实现对标定物重量的准确测量。该实验选择梁作为受力的载体,将应变片黏贴在梁上下表面,通过对灵敏系数的调整建立静态应变仪所测得的应变与标定物重量之间的关系。实验结果表明,改造后的静态应变仪作为电子秤使用时,能够准确测量出标定物的重量,实验数据的稳定性和重复性均得到了验证。实验将材料力学的理论知识与电测法相结合,拓宽了电测法在材料力学实验教学中的应用范围,也激发了学生的创新思维,具有研究性、综合性和创新性。

基于人工智能技术的铁路电子公文数据智能化分析及关联方法研究

利用大数据、人工智能、超大规模预训练模型等技术,研究铁路行业复杂场景下电子公文数据智能化分析及关联方法。介绍电子公文智能化提升总体架构、关键技术,为铁路电子公文数据智能化分析的远期场景提供方法性探索,从而充分挖掘铁路电子公文资源价值,提升公文办理质量和效率。

电子汽车衡检定分析

电子汽车衡作为测量大型货物计量的主要设备,是贸易往来的主要计量设备。在使用一段时间后,相关人员需要根据国家相关标准和规定对其进行检定,以减少使用过程中数据误差的产生,这也是保障行业进步与发展的关键。本文主要针对现阶段电子汽车衡检定工作开展的重要性以及检定工作要点进行分析,希望能够为电子汽车衡的使用提供参考。

CK6E系列电子皮带秤秤台故障自动切换方法的研究

对电子皮带秤压力传感器故障、两个应急秤秤台故障产生的原因进行研究,通过在电控PLC程序编写中增加秤台切换功能,解决秤台在压力传感器故障、秤体水平和垂直故障时的无缝切换,确保电子秤计量的准确性和物料运行的流畅性。试验结果表明,在使用秤台故障自动切换方法后,车间生产过程中再没有出现因电子秤故障引起的物料中断、停机现象。