内容自适应编码的研究与应用实践

本文探讨了内容自适应编码的背景和研究现状,并探索实践了基于内容自适应的预测模型,证实内容自适应编码能获得比传统ABR方案更优的效果,在降低码率的同时达到较好的主观质量一致性。     

钝化层退火工艺引入的氢对P-Flash存储器耐久性的影响

研究了钝化层退火工艺引入的氢对P-Flash存储器耐久性的影响,建立了这一影响的物理模型,阐明了耐久性退化的机理。在四种不同测试条件下,对P-Flash存储器进行了编程/擦除的耐久性测试。测试结果表明,在高温且延时的条件下,器件的耐久性最差。耐久性与编程/擦除之间的延时相关,延时越长,耐久性衰减越严重。在器件编程后的延时过程中,SiO₂/Si界面处被氢原子钝化的硅悬挂键发生断裂。氢原子的不稳定性导致更多的界面陷阱电荷和氧化层电荷的产生,使得阈值电压负向偏移,造成负偏压温度的不稳定。通过优化BEOL工艺,可有效改善P-Flash存储器的耐久性。     

基于应用的光伏电站电缆优化设计

通过跟踪湖南地区不同类型电站的实际发电数据,统计分析电站逆变器全年各个阶段的发电输出数据,得到不同类型电站如组件平铺和最佳倾角、组串逆变和集中逆变的发电效率,并通过发电效率计算光伏电站的效率修正系数Kη。在电站电缆设计选型时,以电站容量计算光伏电站设备的理论输出功率和理论输出电流,再乘以效率修正系数Kη,结合当地光伏电站电缆的具体敷设环境系数,计算出光伏电缆的校正电流,作为电缆选型的依据。通过引入效率修正系数Kη进行电站电流的计算,可以充分地利用现有电站的运行维护经验数据,在设计阶段优化电缆截面选择,从而降低电站建设成本,节约项目投资,提高企业经济效益。     

东营市中小河流水文设施建设管理探讨

中小河流水文设施布置过于分散,站点多、分布面广,单站工程投资规模小、整体工程投资规模大,工程建设专业性强,建成后主要用于中小河流水文监测。针对工程项目的特点,工程建设管理需要采取有效措施。本文就东营市中小河流水文监测设施新建水文站工程建设管理作简要探讨。     

白鹤滩水电站右岸坝基柱状节理玄武岩开挖施工技术

白鹤滩水电站右岸坝基高程590.00m以下为P_2β_3~3层柱状节理玄武岩,岩体内微裂隙发育,整体性差。为控制坝基柱状节理玄武岩开挖后卸荷松弛,采用双保护层方式开挖,预留保护层厚度5m,保护层顶面参照建基面要求实施预裂爆破技术开挖,然后利用保护层作为岩石盖重进行坝基固结灌浆及锚筋桩预锚等基础处理,以增加坝基柱状节理玄武岩的力学性能及岩体完整性。根据坝基开挖体型特点,预留保护层上部陡坡段采用常规预裂爆破技术开挖,下部缓坡段和水平段采用复合消能爆破技术开挖,既保证了建基面开挖质量,也加快了施工进度,实现了大坝混凝土如期顺利开浇。     

全过程电压稳定故障筛选和排序方法及辅助决策

提出了全过程(机电暂态和中长期)电压稳定故障筛选和排序方法。中长期电压失稳的可能性不可忽视,但是中长期分析难以应对大量故障。为了克服这一困难,通过静态、暂态和中长期三个分析阶段进行严重故障的筛选和排序。首先利用静态和暂态分析手段从预想故障集中筛选出可能导致中长期电压失稳的故障,再利用中长期分析手段针对这一部分故障进行校核。基于实际电网对所提方法进行了测试,静态分析阶段有效筛选出了功率裕度较低的故障;暂态分析阶段筛选出了少量导致过励和电压稳定裕度较低的故障;中长期分析阶段从中筛选出了中长期电压失稳故障;针对电压失稳故障,在关键节点制定了辅助决策,实施后能够使系统保持电压稳定。     

Carrier transport across grain boundaries in polycrystalline silicon thin film transistors

We established a model for investigating polycrystalline silicon (poly-Si) thin film transistors (TFTs). The effect of grain boundaries (GBs) on the transfer characteristics of TFT was analyzed by considering the number and the width of grain boundaries in the channel region, and the dominant transport mechanism of carrier across grain boundaries was subsequently determined. It is shown that the thermionic emission (TE) is dominant in the subthreshold operating region of TFT regardless of the number and the width of grain boundary. To a poly-Si TFT model with a 1 nm-width grain boundary, in the linear region, thermionic emission is similar to that of tunneling (TU), however, with increasing grain boundary width and number, tunneling becomes dominant.     

Dielectric properties of Bi<Subscript>4</Subscript>Ti<Subscript>3</Subscript>O<Subscript>12</Subscript> ceramics by impedance spectroscopic method

Various lead-free ceramics have been investigated in search for new high-temperature dielectrics. In particular, Bi₄Ti₃O₁₂ is a type of ferroelectric ceramics, which is supposed to replace leadcontaining ceramics for its outstanding dielectric properties in the near future. Ferroelectric ceramics of Bi₄Ti₃O₁₂ made by conventional mixed oxide route have been studied by impedance spectroscopy in a wide range of temperature. X-ray diffraction patterns show that Bi₄Ti₃O₁₂ ceramics are a single-phase of ferroelectric Bi-layered perovskite structure whether it is calcined at 800 °C or after sintering production. This study focused on the effect of the grain size on the electric properties of BIT ceramics. The BIT ceramics with different grain sizes were prepared at different sintering temperatures. Grain becomes coarser with the sintering temperature increasing by 50 °C, relative permittivity and dielectric loss also change a lot. When sintered at 1 100 °C, r values peak can reach 205.40 at a frequency of 100 kHz, the minimum dielectric losses of four different frequencies make no difference, all close to 0.027. The values of E _a range from 0.52 to 0.68 eV. The dielectric properties of the sample sintered at 1 100 °C are relatively better than those of the other samples by analyzing the relationship of the grain, the internal stresses, the homogeneity and the dielectric properties. SEM can better explain the results of the dielectric spectrum at different sintering temperatures. The results show that Bi₄Ti₃O₁₂ ceramics are a kind of dielectrics. Thus, Bi₄Ti₃O₁₂ can be used in high-temperature capacitors and microwave ceramics.     

基于Logistic模型分析理工科大学生的就业影响因素

通过问卷调查,用多元统计分析中的二项式Logistic回归模型,对重庆市4所理工科院校毕业生的就业影响因素进行实证分析,结果表明:性别特征、学习成绩、英语水平、获奖等级、担任学生干部、社会实践经历、理想薪酬、意向就业区域、期望单位性质对就业的影响较大.从合理调整学科和专业设置、加强就业创业指导、转变就业观念、构建多学科交叉培养模式、提高毕业生素质等方面提出了相应对策.     

催化裂化油浆系统结垢原因及解决措施

本文讨论了催化裂化(FCC)油浆系统的结垢原因及减少其结垢的措施。介绍了近年来国内外催化裂化油浆的发展状况和应用效果。最后针对我国的实际情况提出了一些设想和建议。