Fe掺杂对BiTaO_4陶瓷样品介电和铁电特性的影响

为探究Fe掺杂对BiTaO4陶瓷样品介电特性和铁电特性的影响,采用传统固相烧结法制备了Bi Ta1-xFexO4-x(x=0,0.01,0.03)陶瓷样品,利用X线衍射仪和扫描电子显微镜对样品的晶体结构和表面形貌进行分析,利用精密阻抗分析仪和铁电分析仪对样品的介电性能和铁电性能进行检测.结果表明:Fe掺杂没有明显改变样品的晶体结构;随着Fe掺杂量的增加,样品的介电常数表现出较好的稳定性,介电损耗略有减小,且基本保持在tanδ=0.05以下,其漏电流先增大后减小,且掺杂样品均可得到比较完整的电滞回线.     

高等教育成本分担问题研究--以研究生教育为例

高等教育成本承担机制造成了教育经费紧张,研究生培养质量下降,导师责任心降低等问题。实行教育成本分担有着现实的必要性和可行性。而高等教育成本分担机制同样有着深厚的理论基础:公共产品理论、人力资本理论、教育成本分担理论和比较收益理论。研究生教育实行成本分担,可以有效解决以上问题,促进我国高等教育特别是研究生教育的发展。     

基于Bert股吧舆情分析的特征融合股价走势预测研究

传统股价预测模型往往只考虑时序性数据且局限于模型自身机制,而忽略舆情对股价的影响,导致预测精度不高,针对该问题,提出基于 Bert 股吧舆情分析的特征融合预测模型对股价收盘价进行涨跌幅预测。 首先,采用Bert 自然语言处理对股吧舆情以及公司公告政策进行情感分类,并转化为虚拟变量,构建金融舆情情感特征库;然后将金融舆情特征库和时序性数据合并构建特征融合矩阵;最后输入长短期记忆网络模型(LSTM)进行股价收盘价预测,并得出股价的涨跌结果。 以华银电力(600744. SH)为例进行实证分析,实验结果表明:引入股票情感特征后的模型,得到的股价走势准确率上升了 8. 63%,预测收盘价的回归指标 FMAPE FRMSE 分别下降了 23. 59%、22. 9%,R2 提高了 8. 11%,证明引入新的舆情情感特征在实际预测中能提高股价预测的准确率,可以作为精准预测股价走势的手段。     

Development of Postgraduate Education in Chemical Engineering

1 Development of Postgraduate Education There were only 200 postgraduates were honored master degree from the year 1935 to 1949 in old China. While, after the establishment of new China, the postgraduate education has developed in a certain degree, there were 23,000 postgraduates were enrolled from 1950 to 1965, and there were no postgraduates during the period of 1966 to 1977 due to the "culture revolution".     

CHARACTERIZATION OF SOL-GEL-DERIVED ZrO2 FILM BY PHOTOTHERMAL RADIOMETRY

In modern industry,thin film on the substratc has much important role to decide the properties of product, especially for electrical, optical and wear-resistant etc, production. There are some technical methods to prepare thin film,including plasma spray,physical vapor deposition (PVD),chemical vapor deposition (CVD) and sol-gel,etc. Among of them,sol-gel method has been developed a popular tech nique for preparing thin films.     

西洋参总皂苷抗小鼠心肌缺氧作用的研究

目的:观察了解西洋参总皂苷在不同缺氧条件下对小鼠缺氧性损伤的保护作用.方法:分别建立乏氧性缺氧、特异性心肌缺氧及亚硝酸钠中毒性缺氧实验动物模型,观察西洋参总皂苷在不同缺氧条件下对小鼠存活时间的影响.结果:与生理盐水对照组相比,西洋参总皂苷(40 mg/kg、80 mg/kg)能明显延长乏氧性缺氧小鼠存活时间,差异有显著性(P0.01);特异性心肌缺氧模型组小鼠存活时间较生理盐水对照组明显缩短,差异有显著性(P0.01);与特异性心肌缺氧模型组相比,西洋参总皂苷(20 mg/kg、40 mg/kg、80 mg/kg)能明显延长特异性心肌缺氧小鼠存活的时间,差异有显著性(P0.01);与亚硝酸钠中毒性缺氧模型组相比,西洋参总皂苷(20 mg/kg、40 mg/kg、80 mg/kg)能明显延长亚硝酸钠中毒小鼠存活的时间,差异有显著性(P0.01或P0.05).结论:西洋参总皂苷能提高小鼠在不同缺氧条件下的耐缺氧能力,表明西洋参总皂苷具有一定的提高机体耐缺氧能力的作用.     

Effect of retained austenite and nonmetallic inclusions on the thermal/electrical properties and resistance spot welding nuggets of Si-containing TRIP steels

Five advanced high-strength transformation-induced plasticity(TRIP) steels with different chemical compositions were studied to correlate the retained austenite and nonmetallic inclusion content with their physical properties and the characteristics of the resistance spot welding nuggets. Electrical and thermal properties and equilibrium phases of TRIP steels were predicted using the JMatPro? software. Retained austenite and nonmetallic inclusions were quantified by X-ray diffraction and saturation magnetization techniques. The nonmetallic inclusions were characterized by scanning electron microscopy. The results show that the contents of Si, C, Al, and Mn in TRIP steels increase both the retained austenite and the nonmetallic inclusion contents. We found that nonmetallic inclusions affect the thermal and electrical properties of the TRIP steels and that the differences between these properties tend to result in different cooling rates during the welding process. The results are discussed in terms of the electrical and thermal properties determined from the chemical composition and their impact on the resistance spot welding nuggets.     

基于改进Sobel算法的焊缝X射线图像气孔识别方法

提出一种具有自适应能力的焊缝X射线图像气孔检测方法.通过局部动态阈值分割法设计了多方向的焊缝X射线图像模板,采用Sobel算法对复杂背景下的焊缝进行边缘检测和区域标记,并在标记区域对原始图像x和y方向的灰度梯度进行分析,以增强小气孔和粘连气孔的识别能力.检测应用效果表明,所提出的方法具有良好的自适应能力且准确快速,能够有效地克服人工评片中产生的漏判与误判等缺点,并且能够存储和查询检测数据.     

论独立学院实验室的管理与开放——以三亚学院为例

随着科学技术与经济的快速发展,人们对新世纪的人才要求来越高,越来越重视人才的综合素质。高等院校作为培养人才的重要基地,除了培养学生的学习能力,还要培养学生的动手能力、创新能力。高校实验室就是一个培养学生动手能力、创新能力和学术交流的基地,其在人才培养中担当了相当重要的地位。因此,高校实验室的管理与开放就显得特别重要。然而,随着各高校办学规模的迅速扩大,学科专业的不断拓宽,传统的实验室管理方法存在着许多问题。该文以三亚学院理工学院电子实验教学中心为例,分析了独立学院实验室的管理与开放问题。