TiO_2纳米晶的研究进展

纳米TiO2具有诸多优良特性,有着极好的应用前景。特别是在光催化领域,纳米TiO2的光催化作用可以把光能转变为电能和化学能,实现许多通常情况下难以实现或不可能进行的反应;用于环境治理,它的分散性以及对紫外线较好的屏蔽作用,使其广泛用于制备化妆品、防护漆等;此外,纳米TiO2还可作为吸收、反射红外光、隐身、静电屏蔽和增强增韧等材料。文章综述了纳米TiO2的特性、主要制备方法和主要应用领域,并结合实际应用中存在的问题,对纳米TiO2的发展趋势作出展望。     

A low specific on-resistance SOI MOSFET with dual gates and a recessed drain

A low specific on-resistance(Ron,sp) integrable silicon-on-insulator(SOI) metal-oxide semiconductor field-effect transistor(MOSFET) is proposed and investigated by simulation.The MOSFET features a recessed drain as well as dual gates,which consist of a planar gate and a trench gate extended to the buried oxide layer(BOX)(DGRD MOSFET).First,the dual gates form dual conduction channels,and the extended trench gate also acts as a field plate to improve the electric field distribution.Second,the combination of the trench gate and the recessed drain widens the vertical conduction area and shortens the current path.Third,the P-type top layer not only enhances the drift doping concentration but also modulates the surface electric field distributions.All of these sharply reduce Ron,sp and maintain a high breakdown voltage(BV).The BV of 233 V and Ron,sp of 4.151 mΩ·cm2(VGS = 15 V) are obtained for the DGRD MOSFET with 15-μm half-cell pitch.Compared with the trench gate SOI MOSFET and the conventional MOSFET,Ron,sp of the DGRD MOSFET decreases by 36% and 33% with the same BV,respectively.The trench gate extended to the BOX synchronously acts as a dielectric isolation trench,simplifying the fabrication processes.     

A low on-resistance triple RESURF SOI LDMOS with planar and trench gate integration

A low on-resistance(Ron,sp) integrable silicon-on-insulator(SOI) n-channel lateral double-diffused metal-oxide-semiconductor(LDMOS) is proposed and its mechanism is investigated by simulation.The LDMOS has two features:the integration of a planar gate and an extended trench gate(double gates(DGs));and a buried P-layer in the N-drift region,which forms a triple reduced surface field(RESURF)(TR) structure.The triple RESURF not only modulates the electric field distribution,but also increases N-drift doping,resulting in a reduced specific on-resistance(Ron,sp) and an improved breakdown voltage(BV) in the off-state.The DGs form dual conduction channels and,moreover,the extended trench gate widens the vertical conduction area,both of which further reduce the Ron,sp.The BV and Ron,sp are 328 V and 8.8 m.cm2,respectively,for a DG TR metal-oxide-semiconductor field-effect transistor(MOSFET) by simulation.Compared with a conventional SOI LDMOS,a DG TR MOSFET with the same dimensional device parameters as those of the DG TR MOSFET reduces Ron,sp by 59% and increases BV by 6%.The extended trench gate synchronously acts as an isolation trench between the high-voltage device and low-voltage circuitry in a high-voltage integrated circuit,thereby saving the chip area and simplifying the fabrication processes.     

韧性材料在多向动应力状态下的动强度理论

韧性材料的多向静应力状态,有最大正应力、最大剪应力等强度理论,作为强度设计计算的判断准则,而在多向动应力状态下的强度理论是什么呢?至今尚未有确切的定论。本文根据韧性材料的疲劳破坏机理,提出了在多向动应力状态下,材料的某一截面上沿某个方向首先开始破坏,主要是由于其剪应力时间历程的作用最不利所引起的,并同时考虑了该截面上的正应力时间历程的影响,建立了韧性材料在多向动应力状态下疲劳破坏截面的位置及其寿命的计算公式,作为动强度设计计算的判断准则,简称之为动强度理论。     

具有行星传动的机械传动系统的弹性动态建模

讨论了具有行星传动的机械传动系统的弹性动态方程的建立方法，将行星传动和定轴传动化成基本子系统，建立子系统的刚度和阻尼矩阵，综合各子系统，最后获得整体传动系统的弹性动态方程。     

双鼠笼型电动机驱动行星传动调速的起升机构

文中讨论了双鼠笼型电动机驱动行星传动调速的起升机构。其调速是由行星传动和两个鼠笼型电动机的不同驱动的相互匹配而实现的。一般可以达到６－７挡速率，起动时各挡可以逐渐增快，或制动时逐渐减慢，也可以各挡独立长期工作，以满足不同工况的需要。     

塔机水平臂主载荷下线性和非线性变形与内力

对塔机双吊点水平动臂在主载荷下的线性和非线形变形，拟建立其通用的变形方程组，以便对其变形和内力进行普遍的计算，吊重和自重为主要载荷，对设计计算有重要意义．     

Rijke管热声振荡的稳定性切换行为研究

采用数值方法模拟了强弱两种阻尼条件下传热迟滞时间对一维Rijke管热声系统稳定性的影响,发现Rijke管系统存在稳定性切换现象.在推导了无量纲形式的管内声波动量方程和能量方程之后,利用Galerkin方法对控制方程进行展开并在时间域内数值求解.分析了强阻尼和弱阻尼条件下,给定热源的Rijke管热声振荡的稳定性与传热迟滞时间的关系.结果显示:在两类阻尼条件下,持续增大传热与速度的迟滞时间,系统均呈现出稳定性切换现象,即系统在稳定和不稳定两个状态间持续转变;但弱阻尼系统的不稳定区域宽于强阻尼系统的不稳定区域,系统最大振幅相对增大,且系统热声振荡的主模态在不同模态之间发生转换.最后,通过求解系统各阶模态极限环幅值随传热迟滞时间的变化,发现Rijke管热声振荡稳定性切换现象与迟滞时间存在近似周期性关系.     

A low specific on-resistance SOI MOSFET with dual gates and recessed drain

A low specific on-resistance (R_on,sp) integrable silicon-on-insulator (SOI) metal-oxide semiconductor field-effect transistor (MOSFET) is proposed and investigated by simulation. The MOSFET features a recessed drain as well as dual gates which consist of a planar gate and a trench gate extended to the buried oxide layer (BOX) (DGRD MOSFET). First, the dual gates form dual conduction channels, and the extended trench gate also acts as a field plate to improve the electric field distribution. Second, the combination of the trench gate and the recessed drain widens the vertical conduction area and shortens the current path. Third, the P-type top layer not only enhances the drift doping concentration but also modulates the surface electric field distributions. All of these sharply reduce R_on,sp and maintain a high breakdown voltage (BV). The BV of 233 V and R_on,sp of 4.151 mΩ·cm² (V_GS=15 V) are obtained for the DGRD MOSFET with 15-μm half-cell pitch. Compared with the trench gate SOI MOSFET and the conventional MOSFET, R_on,sp of the DGRD MOSFET decreases by 36% and 33% with the same BV, respectively. The trench gate extended to the BOX synchronously acts as a dielectric isolation trench, simplifying the fabrication processes.     

疾恶真推祢正平——我校创始人刘文典

“养生未羡嵇中散疾恶真推祢正平”这是五十九年前,我国近代民主革命家、思想家章炳麟(字太炎,1868—1939)先生赠给他的学生、我校最早创始人刘文典教授的一幅对联。这幅对联不仅写出了我校前身——省立安徽大学初创时期一段惊心动魄的斗争,而且赞美了刘文典教授一生热爱祖国、热心教育、在邪恶势力面前威武不屈的崇高品格,很是珍贵。