Polyetherimide substrates for future high density optical data storage

Polyetherimide (PEI) substrate for next‐generation high density optical data storage is fabricated and characterized. Cover‐layer incident or first‐surface recording configurations do not require optical properties of the substrate, which are the prerequisite conditions for the conventional material of polycarbonate (PC). Instead of the optical properties, good mechanical properties with a sufficient transcribability are required. Even though PEI has higher glass transition temperature than that of PC, a microscopic transcribability of PEI is comparable with PC by laminating a thermal insulation layer on the backside of a stamper to retard the heat flow. A macroscopic warpage of PEI substrate is smaller than that of PC substrates, which reduces tilt and servo burden. The lowest critical speed coupled with the flutter of PEI substrate is larger than that of PC substrate because of the mechanical properties of PEI. POLYM. ENG. SCI., 48:97–101, 2008. © 2007 Society of Plastics Engineers     

装配式基坑支护结构在广州地区的应用

装配式基坑支护结构是将基坑支护的围护结构部分在工厂预制成型,再在现场与撑或锚装配组成的支护结构。工程实践表明,此项技术可有效节省工程投资、缩短工期。     

百年夫妻树 专业安全移新居——120年广玉兰搬迁实录

“深情厚意含笑花，尽在嫣然一笑中。”“一点瓜香破醉眠，误他诗客枉流涎。”这是诗人对含笑的赞美。她生长在南方，有淡黄、白、紫等色，花以紫色为大，香以白色为最，形似小白莲，春秋两度开花，花香四溢。宋朝诗人杨万里特别喜爱含笑，于杭州宅内庭院中栽种多株，闲来赏花赋诗多首，其中如《含笑花》七律云：“菖蒲节序芰荷时，翠羽衣裳白玉肌；暗折花房须日暮，遥将香气报人知。半开微吐长怀宝，欲说还休竟俯眉；树脆枝柔惟叶健，不消更画只消诗。”     

一种基于新型寄存器结构的逐次逼近A/D转换器

介绍了一种10位CMOS逐次逼近型A/D转换器。在25 kSPS采样频率以下,根据模拟输入端输入的0~10 V模拟信号,通过逐次逼近逻辑,将其转化为10位无极性数字码。转换器的SAR寄存器结构采用了一种新的结构来实现D触发器。该转换器采用3μm CMOS工艺制作,信噪比为49 dB,积分非线性为±0.5 LSB。     

SOC设计中的浮动压焊块电源/地线网络设计和优化

随着VLSI工艺技术的发展和芯片规模的不断增加，尤其是在SOC设计中，原有的那种供电压焊块只能位于芯片边缘的确定益的模式已经不能够满足整个电路性能的需要。在很多情况下，依靠在电源线的拓扑结构确定后的线宽优化，还是无法保证在有限的布线资源下为电路提供可靠的高性能的供电需求。由此，出现了在芯片边缘上浮动放置压焊块及在芯片的顶部放置供电压焊块阵列的方法。文中提出了一种用于SOC设计中新的基于树型结构的浮动压焊块的电源／地线网络优化算法，经过MCNC电路实例测试后得到明显的优化结果。     

A global output-feedback controller for stabilization and tracking of underactuated ODIN: A spherical underwater vehicle

This paper presents a method to design an output-feedback controller that simultaneously solves global asymptotic stabilization and tracking of an underactuated omni-directional intelligent navigator—a spherical underwater vehicle moving in a horizontal plane (i.e. at a constant depth). The vehicle does not have a sway actuator and has only position and orientation measurements available. The control development is based on Lyapunov's direct method, backstepping technique and use of interconnected structure of the vehicle dynamics. Numerical simulations demonstrate the results.     

基于非均匀星座的改进ARQ方案及其性能分析

本文针对调制阶数大于4的MPSK和MQAM调制，在重传中采用非均匀星座图和符号比特重新排序，提出了一种改进的ARQ方案。通过对AWGN信道下ARQ方案进行理论分析和数值仿真，表明基于非均匀星座的新方案在信道条件较差时能有效地提高重要比特的可靠性，若重传中结合符号比特重排和分组合并，则可使接收端解调合并后的比特可靠性趋于均匀且总体得到提高，从而有效地减少重传次数，提高系统的吞吐率。由于本文所提方案并不改变调制解调规则和数据分组长度，故容易实现和控制。     

Verification of submodeling technique in thermomechanical reliability assessment of flip-chip package assembly

In this paper we verified the submodeling technique applied in the thermomechanical reliability assessment of a flip-chip BGA under accelerated thermal cycling test conditions. Since the steady-state creep model was implemented for the solder bump to better represent its realistic mechanical behavior, submodeling procedures developed specifically for path-dependent thermomechanical problems were considered. A detailed global model for the flip-chip BGA was built up to verify submodeling solutions. This model also served as a benchmark to examine solution discrepancies caused by different simplifications of the global model.