IBM集群式高性能计算机体系结构及气象应用

本文详细描述了南京信息工程大学引进的IBM集群式高性能计算机的体系结构,并结合了WRF气象模式具体应用,分析了高性能计算机体系结构与气象领域之间的关系。     

Highly Ordered Mesoporous Silicon Carbide Ceramics with Large Surface Areas and High Stability

Highly ordered mesoporous silicon carbide ceramics have been successfully synthesized with yields higher than 75 % via a one‐step nanocasting process using commercial polycarbosilane (PCS) as a precursor and mesoporous silica as hard templates. Mesoporous SiC nanowires in two‐dimensional (2D) hexagonal arrays (p6m) can be easily replicated from a mesoporous silica SBA‐15 template. Small‐angle X‐ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images show that the SiC nanowires have long‐range regularity over large areas because of the interwire pillar connections. A three‐dimensional (3D) bicontinuous cubic mesoporous SiC structure (Ia3d) can be fabricated using mesoporous silica KIT‐6 as the mother template. The structure shows higher thermal stability than the 2D hexagonal mesoporous SiC, mostly because of the 3D network connections. The major constituent of the products is SiC, with 12 % excess carbon and 14 % oxygen measured by elemental analysis. The obtained mesoporous SiC ceramics are amorphous below 1200 °C and are mainly composed of randomly oriented β‐SiC crystallites after treatment at 1400 °C. N₂‐sorption isotherms reveal that these ordered mesoporous SiC ceramics have high Brunauer–Emmett–Teller (BET) specific surface areas (up to 720 m² g^–1), large pore volumes (～ 0.8 cm³ g^–1), and narrow pore‐size distributions (mean values of 2.0–3.7 nm), even upon calcination at temperatures as high as 1400 °C. The rough surface and high order of the nanowire arrays result from the strong interconnections of the SiC products and are the main reasons for such high surface areas. XRD, N₂‐sorption, and TEM measurements show that the mesoporous SiC ceramics have ultrahigh stability even after re‐treatment at 1400 °C under a N₂ atmosphere. Compared with 2D hexagonal SiC nanowire arrays, 3D cubic mesoporous SiC shows superior thermal stability, as well as higher surface areas (590 m² g^–1) and larger pore volumes (～ 0.71 cm³ g^–1).     

Design techniques of low-power embedded EEPROM for passive RFID tag

This paper presents an optimized embedded EEPROM design approach which has reduced the power significantly in a short-range passive RFID tag. The proposed array control circuit employs an improved structure to minimize the leakage of memory bit cells. With the proposed array circuit design, the passive RFID tag can operate drawing a low quiescent current. The RFID tag with the proposed EEPROM was fabricated in a standard 0.35-μm four-metal two-poly CMOS process. Measurement results show that the erasing/writing current is 45 μA, and reading current consumption is 3 μA with a supply voltage of 3.3 V. The data read time is 300 ns/bit.     

First-principles investigation of the optical properties of CuIn(SxSe1–x)2

We optimized the lattice structure of sulfur-doped CuInSe₂ using first principles. The lattice constants for CuIn(S_xSe_1–x)₂ vary linearly with x according to a(x)=–0.02828x+0.58786 nm and c(x)=–0.05692x+1.1834 nm, which agree well with experimental data. The optical properties of CuIn(S_xSe_1–x)₂ were then systematically investigated using first-principles calculations with the HSE06 functional. We present data for the complex dielectric function, refractive index, extinction coefficient, reflectivity index, absorption coefficient, and optical bandgap for CuIn(S_xSe_1–x)₂. The optical bandgap E_g obtained from the absorption coefficient is 1.07 eV for CuInSe₂ and 1.384 eV for CuInS₂. These values are very close to experimental results, indicating that first-principles calculations can yield accurate bandgap values. The optical bandgap of CuIn(S_xSe_1–x)₂ increases linearly with the sulfur concentration according to E_g=0.3139x+1.0825 eV.     

一种基于改进FFT的MPSK载波估计方法

针对多进制相移链控(MPSK)信号相干解调中载波同步问题,提出一种基于Zoom FFT及频域内插的方法进行载波提取。该方法通过信号的非线性变换,在时频域内实现载波频率的粗估计,在此基础上通过频域内的插值校正实现载波的准确提取。仿真试验结果表明,本算法提取的载波具有较高的准确性,估计的最大相对误差只有10-6量级。该方法不需要特定图案的前导字,结构简单,可估计的载波频率适应范围大,在高信噪比的情况下硬件实现系统实时性好。     

一种改进的光载波抑制产生光毫米波的方法

为了延长光毫米波的传输距离,提出了一种改进的光载波抑制产生光毫米波的方法。在中心站采用马赫-曾德尔调制器将射频信号调制到光载波上产生光载波抑制调制光信号,再将产生光信号的2个边带分离,将2.5Gbit/s数据信号调制到其中1个边带上,再与未调信号耦合后产生光毫米波并通过光纤传送至基站。在基站中通过光电转换器产生电毫米波。从理论上分析了这种光毫米波的传输特性并通过实验验证了光毫米波在光纤中可以传输40km。仿真和实验结果表明,这种方式产生的光毫米波具有很好的抗色散能力,延长了传输距离。     

基于声表面波技术的飞机结冰预警系统研究

飞机结冰严重影响飞行安全,现有结冰传感器都只在飞机结冰后才进行告警。利用声表面波结冰传感器及声表面波温度传感器设计了飞机结冰预先告警系统。研究了声表面波结冰传感器的原理,并设计了传感器信号的告警逻辑关系,通过等效电路对无线声表面波冰传感器进行仿真。仿真结果表明,声表面波飞机结冰预警系统可用以降低结冰信号的虚警率。     

一种实用化的数字体温测量算法及其ASIC实现

传统电子体温计芯片采用大量复杂模拟模块,功耗和成本都较高.文章提出了一种适合电子体温计芯片采用的温度测量算法,基于上华(CSMC)1.0μm MGLVCMOS标准工艺,设计出实用化的数字体温测量电路,并绘制了整个电路的版图.利用Spectre、Verilog_XL及Matlab对系统电路进行仿真测试,结果显示所设计的数字体温测量电路在+32.0℃～+42.0℃(+90.0°F ～+108.0°F)的温度范围内可以实现摄氏和华氏两种模式的测量,具有0.1℃(0.2°F)的精度,1.5V电源电压下系统平均电流仅为100μA,整个电路呈现低功耗和高集成度的特点.     

Multifunctional Fluorene‐Based Oligomers with Novel Spiro‐Annulated Triarylamine: Efficient,Stable Deep‐Blue Electroluminescence,Good Hole Injection,and Transporting Materials with Very High Tg

A series of fluorene‐based oligomers with novel spiro‐annulated triarylamine structures, namely DFSTPA, TFSTPA, and TFSDTC, are synthesized by a Suzuki cross‐coupling reaction. The spiro‐configuration molecular structures lead to very high glass transition temperatures (197–253 °C) and weak intermolecular interactions, and consequently the structures retain good morphological stability and high fluorescence quantum efficiencies(0.69–0.98). This molecular design simultaneously solves the spectral stability problems and hole‐injection and transport issues for fluorene‐based blue‐light‐emitting materials. Simple double‐layer electroluminescence (EL) devices with a configuration of ITO/TFSTPA (device A) or TFSDTC (device B)/ TPBI/LiF/Al, where TFSTPA and TFSDTC serve as hole‐transporting blue‐light‐emitting materials, show a deep‐blue emission with a peak around 432 nm, and CIE coordinates of (0.17, 0.12) for TFSTPA and (0.16, 0.07) for TFSDTC, respectively, which are very close to the National Television System Committee (NTSC) standard for blue (0.15, 0.07). The maximum current efficiency/external quantum efficiencies are 1.63 cd A^?1/1.6% for device A and 1.91 cd A^?1/2.7% for device B, respectively. In addition, a device with the structure ITO/DFSTPA/Alq₃/LiF/Al, where DFSTPA acts as both the hole‐injection and ‐transporting material, is shown to achieve a good performance, with a maximum luminance of 14 047 cd m^?2, and a maximum current efficiency of 5.56 cd A^?1. These values are significantly higher than those of devices based on commonly usedN,N′‐di(1‐naphthyl)‐N,N′‐diphenyl‐[1,1′‐biphenyl]‐4,4′‐diamine (NPB) as the hole‐transporting layer (11 738 cd m^?2 and 3.97 cd A^?1) under identical device conditions.     

背入射Al_(0.42)Ga_(0.58)N/Al_(0.40)Ga_(0.60)N异质结p-i-n太阳光盲紫外探测器

在蓝宝石上用MOCVD生长的材料制备了背入射Al0.42Ga0.58N/Al0.40Ga0.60N异质结p-I-n太阳光盲紫外探测器.从器件的正向Ⅰ-Ⅴ特性曲线计算了理想因子n与串联电阻Rs分别为3和93?器件在零偏压下275nm峰值波长处的外量子效率与探测率分别为9%和4.98×1011cm·Hz1/2/W,分析表明Al0.42Ga0.58N窗口层在275nm波长处的透过率仅为15.7%,是器件外量子效率和探测率偏低的原因之一.