Improve on/off ratio of organic heterojunction transistors by adopting single-sandwich configuration

Organic heterojunction transistors (OHJTs) based on 5,5′″-bis(naphtha-2-yl)-2,2′:5″,2′″-quaterthiophene (NaT₄)/copper-hexadecafluoro-phthalocyanine (F₁₆CuPc) heterojunction were fabricated in single-sandwich and sandwich configurations, respectively. All the devices operated in depletion-accumulation (normally-on) mode. High field-effect mobility of 0.35 cm²/Vs was obtained for all devices, which was higher than that, 0.20 cm²/Vs of the devices with NaT₄ as active layer. The on/off ratio of 1 × 10⁵ was obtained for OHJTs with single-sandwich configuration, which is three orders of magnitude higher than that of OHJTs with sandwich configuration. Compared with OHJTs with sandwich configuration, the higher on/off ratio was mainly determined by the lower off state current in OHJTs with single-sandwich configuration. In OHJTs with single-sandwich configuration, the well-type shield effect of the source and drain electrodes caused a very narrow empty region in F₁₆CuPc film, which is responsible for the lower off state current.     

Development of High Deformability Pipeline Steel

Based on strain-based design, high deformability X70 high strength pipeline steel with dual-phase microstructure has been developed, which can be laid in the seismic, the cold or the deepwater region. The results illustrated that the developed X70 steel has the stress-strain curve like round house and it shows good anti-transformation characteristic, high uniform deformation(≥10%), enhanced n-value(≥0.10), and the low yield-tensile ratio Y/T(≤0.85). The dual-phase microstructure of ferrite and bainite conta...     

Two‐dimensional guidelines for measurement system indices

In this paper, we review two common measurement system indices and a common process capability index. With some simple plots, it will be shown that the traditional guidelines for these measurement system indices can often misdirect improvement efforts. By taking advantage of the relationship between the measurement system indices and the process capability index, two‐dimensional guidelines that can be used as an alternative to the traditional guidelines are developed. These two‐dimensional guidelines are intended to help address adequacy of the measurement system and better direct improvement efforts to where there will be the most benefit. Copyright © 2010 John Wiley & Sons, Ltd.     

一起110kV电容式电压互感器故障诊断与处理

介绍了1例电容式电压互感器例行试验中数据的异常情况,通过对电容分压器的介质损耗因素、电容量试验数据进行纵横比分析,确定了故障的存在,并用自激法试验找出了故障部位,经解体验证并处理了故障,最后分析了故障原因并提出了预防此类故障的建议。     

兼顾稳定性与经济性的交直流系统直流落点选择方法

直流电系统落入受端交流电网的落点选择需要考虑交直流系统的相互作用,主要包括有效短路比、静态电压稳定指标和受端系统的有功功率损耗。文中提出一种兼顾稳定性与经济性的直流落点选择方法。基于数学上解决多目标决策问题的线性加权和法,首先设置各指标的门槛值,然后对其进行归一化处理,采用组合赋权法合理确定权系数,建立目标函数,选出最...     

单支撑旋转超声电机及其速度特性研究

分析了双轴承支撑超声电机的加工和装配误差所造成的定、转子接触界面沿圆周方向压力不均衡的现象,它是造成电机转速波动的主要原因之一。在此基础上,提出了一种单轴承支撑附加调心结构的新方案,通过实现接触界面的压力自平衡,来达到提高电机转速稳定性,同时减小体积、减轻质量的目的。实验结果表明,在电机输出力矩、速度等主要性能指标与原结构电机相比没有下降的前提下,新方案电机的空载转速波动率降低了约40%,质量降低约14%,厚度减小了27.3%。     

基于SRAM型FPGA测试技术的研究

随着FPGA集成度和复杂性的增加,测试显得尤为重要.为了保证数字系统工作的稳定性,首先就要保证FPGA芯片的可靠性.从SRAM型FPGA的内部构造入手,对测试生成和测试故障模型关键技术进行了探讨和研究,解决了测试的故障覆盖率和测试速度之间的矛盾;并搭建了软硬件协同测试平台对测试理论进行了验证,该系统为FPGA芯片的稳定...     

循环水阻垢缓蚀剂在新昌电厂的应用

针对新昌电厂循环水的低硬度、低碱度水质特点,通过大量试验,筛选复配出适合低硬度低碱度水的阻垢缓蚀复合药剂.该阻垢缓蚀复合药剂在新昌电厂1年的应用效果证明,使用缓蚀阻垢剂能够较好地控制循环水系统的腐蚀与结垢问题,通过药剂的协同增效作用,能使循环冷却水的浓缩倍数达到6左右.     

A novel continuous arterial spin labeling approach for CBF measurement in rats with reduced labeling time and optimized signal-to-noise ratio efficiency

Objective  To develop a continuous arterial spin labeling (CASL) perfusion imaging method for cerebral blood flow (CBF) measurement in rats with reduced spin-labeling length and optimized signal-to-noise ratio (SNR _f ) per unit time. Materials and methods  In the proposed method, the longitudinal magnetization of brain tissue water in the imaging slice is prepared into a proper state before spin-labeling, and a post-tagging delay is employed after spin-labeling. The method was implemented on a 4.7 T small animal scanner. Numerical simulations and in vivo experiments were used to evaluate the performance of the method proposed. Results  With the proposed method, absolute CBF could be measured accurately from normal rat with a spin-labeling pulse as short as 400 ms, and yet employing the same formula as that used in the conventional CASL perfusion imaging method for calculation. The method also showed improved SNR _f per unit time over the conventional CASL perfusion imaging method and the pulsed arterial spin labeling perfusion imaging method FAIR. Conclusion  Compared to the conventional CASL perfusion imaging method, the proposed method would be advantageous for CBF measurement in small animals having short vascular transit time in terms of SNR _f per unit time and other benefits brought by shortened spin-labeling pulse.     

超分辨近场结构中二元共晶合金掩膜的工作机制

超分辨近场结构(super-RENS)技术通过在传统光盘结构中插入掩膜结构而实现近场超分辨,是目前最具实用化前景的超高密度光存储技术之一,其中掩膜层的近场光学特性是决定其光存储性能的关键。利用三维时域有限差分法(3D-FDTD)对合金掩膜的近场光强分布进行了数值仿真和分析,提出二元共晶合金薄膜在激光作用下形成的规则微结构可能是以其作为掩膜层的超分辨近场结构光盘产生较高信噪比(SNR)的原因。