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关键词： SiC   MOSFET   Charge pumping   Vth shift   Interface  

摘要： This work focuses on the extraction of Threshold Voltage Shift due to interface trapping from Charge Pumping (CP) measured curves. The proposed mathematical approach analyzes the peak of the charge pumping curve, proportional to the average interface defects density, for estimating the threshold voltage shift due to interface trapping separately from the shift induced by oxide trapping. The high-frequency nature of CP measurements is therefore exploited for the detection of fast states. The analyzed devices are 4H-SiC n-channel MOSFETs and a custom, on-wafer, in-situ measurement setup is used. Under constant current gate stress, positive and negative charge trapping processes are identified; the role of a) charge trapping in the oxide and b) interface states generation is analyzed and described.

摘要： This paper presents a novel deep trench-type SiC MOSFET integrated with Schottky diodes (DT-JMOS) designed to improve oxide reliability and switching performances. In contrast to conventional SiC trench MOSFET with Schottky diodes (CT-JMOS), the DT-JMOS utilizes a narrower JFET region and a P-bot structure, resulting in superior electric field reductions in gate oxide layer to improve reliability. The unique structure also enables double-channel operation and deeper embedded Schottky contacts, significantly enhancing the current conduction capabilities in both the first and third quadrants. Furthermore, simulation results indicate that the DT-JMOS achieves a 97.6 % decrease in gate-to-drain capacitance ( C gd ), leading to a 67.5 % improvement in gate-to-drain charge ( Q gd ), and eventually resulting in reductions by factors of 3.2 and 3.5 for figure of merit Q gd  ×  R on,sp and total switching losses ( E total ), respectively. These attributes suggest that the DT-JMOS is more suitable for high-voltage and high-frequency applications.

摘要： The parallelling of power semiconductor devices is essential for desired current ratings and the system is prone to the current unbalancing due to parameter variations. SiC devices with significant variable threshold voltage due to manufacturing yield and temperature distribution have a consequential possibility of dynamic current unbalancing. This paper presents the peak detection-based current balancing of parallel-connected SiC devices to minimize the turn-on and turn-off current unbalancing. PCB current sensors are used for the measurement and feedback of the signal for this peak detection-based current balancing mechanism.

关键词： MOSFET-type gas sensor   Zinc indium tin oxide (ZITO)   Co-sputtering   X-ray photoelectron spectroscopy (XPS)  

摘要： The growing demand for high-sensitivity and low-power gas sensors has driven the exploration of advanced sensing materials. In this study, we fabricated MOSFET-type gas sensors using co-sputtered zinc indium tin oxide (ZITO) films as sensing layers, with five different films containing varying ratios of indium tin oxide (ITO) and ZnO mixtures. As the Zn content increased, the agglomeration sizes within the films decreased, exhibiting amorphous-like morphology. X-ray photoelectron spectroscopy (XPS) revealed that scarce Zn content induced oxygen vacancies, while the number of hydroxy groups increased with higher Zn content. These material properties of the sensing layers significantly influenced the gas sensing characteristics. At high temperatures (similar to 210 degrees C), the oxygen vacancy-rich sensor showed the highest gas response, whereas the hydroxy-rich sensor exhibited enhanced performance at low temperatures (similar to 150 degrees C). The adjustment of the co-sputtering ratio influences gas response, power consumption, and response time, allowing for the fabrication of sensors optimized for specific applications by comprehensively considering various performance factors. We believe that this method can be applied to the formation of a wide range of sensing materials.

关键词： 微种植体   导板   成功率  

摘要： 目的观察本课题组研发的微种植体植入导板的临床应用效果,并比较其与对照组使用传统方式进行微种植体植入的植入效果差异。方法按照纳入排除标准共计纳入34名患者,试验侧采用微种植体植入导板辅助微种植体的植入,共计植入34枚微种植体。对照侧参考植入术区影像片,依据操作者的经验进行微种植体的植入,共计植入34枚微种植体,分析导板引导下的微种植体植入精确度,并对2组微种植体的植入成功率进行比较。结果试验组植入成功率为97.06%,对照组植入成功率为82.35%,统计分析学结果显示其差异具有统计学意义。结论本课题组研发的微种植体植入导板可提高微种植体植入成功率,值得进一步推广临床使用。

关键词： 工程船   电力系统   电力推进   动力定位   变压器  

摘要： 为了保证船舶航行及推进定位作业的稳定性和安全性,结合大连中远海运重工有限公司建造的12 000 t抬浮力打捞/半潜工程船,对该船各个使用工况下电力系统的设计配置情况、变压器配置、主推进系统及功率管理系统等的设计进行分析。分析结果表明,该项目电力、推进等系统对船舶操作有较高的安全冗余性,满足相关国内及国际标准规范的要求,能够满足船舶各个工况下的操作要求。研究成果可为进一步深入优化打捞/半潜工程船电力系统的设计提供参考。

关键词： 互感器误差预测   注意力机制   长短期记忆网络   Seq2Seq网络  

摘要： 互感器作为电能计量装置组成部分,其运行中的准确可靠直接关系电量交易的公平公正.为准确评估在运互感器计量性能状态,提出了一种注意力机制优化Seq2Seq网络来预测互感器的故障状态,将注意力机制、Seq2Seq网络和双向长短期记忆网络相结合,从在线采集的互感器动态数据中挖掘出顺序语义,建立精准的互感器在线计量状态分析模型.在实验室条件下对运行的电容式电压互感器施加干扰,采用本模型对干扰后互感器运行数据开展误差分析,结果表明:注意机制优化Seq2Seq网络模型可精准剥离外电场干扰对互感器误差的影响,同时证明该方法在计量异常预测方面有较好的识别率.

关键词： 进化粒子滤波器   开源鸿蒙系统   故障诊断   信息熵  

摘要： 鸿蒙系统支持多设备互联和分布式协同操作,使得在故障诊断时,需要考虑到不同设备之间的通信协议、数据同步机制,从而影响故障的表现形式和诊断难度。为此,本文提出基于进化粒子滤波器的轻量型开源鸿蒙系统故障诊断方法,通过分层处理实时运行信息,结合正相关与负相关计算量化异常指标,以提高系统故障诊断的准确性和可靠性。通过量化检测与信息熵方法分析开源鸿蒙系统运行状态,结合进化粒子滤波器优化故障特征融合,利用节点重要性和数据特征融合结果,优化轻量型开源鸿蒙系统的故障诊断过程,提高故障诊断的准确性。实验结果表明,本方法能更准确地识别未知访问源信息,且诊断耗时更短,显著提升系统故障诊断的准确性和效率。

关键词： 改进鲸鱼算法   支持向量机   电力变压器   故障检测  

摘要： 目前潞安化工集团下属各大煤矿井下电力变压器故障特征向量均无法全面反映变压器故障问题,因此无法在最短时间内快速定位故障原因,为了提高电力变压器故障检测的准确度,现设计了一种基于改进鲸鱼算法优化支持向量机的电力变压器故障检测方法。该方法通过收集电力变压器正常运行及出现故障时的关键数据,按照检测的顺序将样本进行分类处理,选取电力变压器故障检测特征量,建立基于鲸鱼算法的预测模型,并采用支持向量机算法对故障进行检测,以此在最短时间内查找出电力变压器真正的故障原因,减少停电对井下安全生产造成的不利影响。实验结果表明,在几个变压器故障类型的识别上,该方法都具有较高的识别率和准确率,完全可以在井下实际故障处理中进行应用。

关键词： 汽轮机   鼓风损失   CFD   叶栅   末级组   长叶片  

摘要： 为研究大功率汽轮机在小负荷状态下末级长叶片区域的鼓风热现象,首先汇总分析了各类相关文献关于旋转叶片类结构搅拌鼓风热现象相关的定量计算公式,然后以国内某大功率600MW超临界发电汽轮机为研究对象,建立了末三级动、静叶片的流场数值模型,依据热力设计数据对其末三级多工况流场进行了数值模拟,获得了其流场分布数据。在数值分析数据的基础上探讨了负荷水平、工质密度和动力黏度等因素与鼓风热损失之间的相关性,分析表明负荷水平与鼓风热损失之间相关性更为明显,其原因主要在于长叶片级组内小负荷状态下流场存在复杂的三维特性;对文献经验公式,在汽轮机末级长叶片鼓风热损失的试算表明,其并不适用于长叶片级组内小负荷状态;最后用线性回归方法建立了鼓风热损失与负荷水平及级最高温度与负荷水平之间的经验性估算公式。本文研究方法及数据可为评估类似结构和功率等级汽轮机鼓风热损失提供参考,为机组安全运行指导提供支持。