基于环形栅和半环形栅N沟道金属氧化物半导体晶体管的总剂量辐射效应研究

在商用0.35 μm互补金属氧化物半导体工艺上制备了两种栅氧化层厚度(t_ox)的条形栅、环形栅和半环形栅N沟道金属氧化物半导体 (n-channel metal oxide semiconductor, 简记为NMOS) 晶体管, 并进行了2000 Gy(Si)的总剂量辐射效应实验. 实验结果显示, 栅氧厚度对阈值电压漂移的影响大于栅氧厚度的3次方. 对于t_ox为11 nm的低压NMOS晶体管, 通过环形栅或半环形栅的加固方式能将其抗总剂量辐射能力从300 Gy(Si)提高到2000 Gy(Si)以上; 而对于t_ox为26 nm的高压NMOS晶体管, 通过环栅或半环栅的加固方式, 则只能在低于1000 Gy(Si)的总剂量下, 一定程度地抑制截止漏电流的增加. 作为两种不同的版图加固方式, 环形栅和半环形栅对同一t_ox的NMOS器件加固效果类似, 环形栅的加固效果略优于半环形栅. 对于上述实验结果, 进行了理论分析并阐释了产生这些现象的原因. 关键词： 环形栅 半环形栅 总剂量 辐射效应     

室温下光纤耦合二极管泵浦Tm:YAP激光器

 为实现室温下小型化、高效率的1.9 mm激光输出,采用793.5 nm激光二极管泵浦Tm:YAP晶体，晶体采用热电制冷及风冷的方式控制在18 ℃，采用1∶1的聚焦耦系统，获得功率为2.2 W、中心波长为1 928 nm的激光输出，光光转换效率为31%，斜率效率达41%。对影响激光输出的耦合输出率、腔型、腔长、晶体工作温度等因素进行了实验分析，实验结果表明：输出功率的变化与温度基本成线性关系,当增加激光谐振腔长时，由于高阶模式损耗加大以及晶体热透镜效应的加重导致腔内损耗加大，输出功率和斜率效率都有所下降。     

Velocity-dependent symmetries and conserved quantities of the constrained dynamical systems

In this paper, we have extefided the theorem of the velocity-dependent symmetries to nonholonomic dynamical systems. Based on the infinitesimal transformations with respect to the coordinates, we establish the determining equations and restrictive equation of the velocity-dependent system before the structure equation is obtained. The direct and the inverse issues of the velocity-dependent symmetries for the nonholonomic dynamical system is studied and the non-Noether type conserved quantity is found as the result. Finally, we give an example to illustrate the conclusion.     

26W near diffraction limited Q-switched green laser based on a diode-end-pumped master oscillator power amplifier

An efficient acousto-optically Q-switched extracavity frequency-doubled 532nm laser based on a diode-end-pumped master oscillator power amplifier (MOPA) is demonstrated. With a type I non-critically phase-matched LBO, 26W of average power at 532nm in a near diffraction limited mode at a repetition rate of 30kHz was generated under 43W pump power of 1064nm Nd:YVO_{4} laser, which correspond to a frequency-doubling conversion efficiency of 60%.     

高效液相梯度洗脱法测定银黄含片中黄芩苷、绿原酸和芦丁

建立了反相高效液相色谱法同时测定银黄含片中的黄芩苷、绿原酸和芦丁。采用HypersilODSC18柱(200mm×4.6mm,粒径5μm),流动相A:甲醇-水-乙酸(10∶88∶2)和流动相B:甲醇-水-乙酸(88∶10∶2),梯度洗脱程序0min(A∶B/97∶3)-10min(A∶B/73∶27)-25min(A∶B/20∶80)-36min(A∶B/20∶80);流速1.0mL/min;检测波长为327nm和280nm;柱温25℃。黄芩苷线性范围为0.051—0.512μg/mL,r=0.9990,样品的平均加标回收率为98.23%,(RSD为2.13%);绿原酸线性范围为0.059—0.592μg/mL,r=0.9996,样品的平均加标回收率为97.61%,(RSD为2.13%);芦丁线性范围为0.087—0.868μg/mL,r=0.999,样品的平均加标回收率为98.56%,(RSD为1.13%),该方法专属性强,结果稳定,重现性好,能有效地控制药品的主成分含量,具有较强的实用价值。     

NaClO/Ca(OH)_2旋转喷雾脱硫脱硝的实验研究

在直径380 mm,高830 mm的工业旋转喷雾吸收塔模型上开展了NaClO/Ca(OH)_2混合液脱除烧结烟气中的SO_2和NO的实验研究,考察了溶液pH,模拟烟气温度,NaClO浓度,SO_2浓度,NO浓度这些操作参数对脱除效率的影响,得出最佳的实验工况为pH=10,T_g=60℃,m_s=6,并在此条件下进行了平行实验,实验结果表明脱硫、脱硝效率可分别达到98%和60%以上。     

改进阈值提升小波和自适应滤波器的开放光路红外光谱去噪

大气污染物的主要组成成分为挥发性有机物(VOCs),傅里叶变换红外光谱技术(FTIR)是现阶段应用广泛的挥发性有机物在线测量方法。开放光路获取到的大气红外光谱(OP-FTIR)易受各种噪声污染,如何有效、快速的去除红外光谱中的噪声是大气在线实时监测系统研究的热点。综合利用提升小波变换结构简单、运算量低的优点以及最小均方误差自适应滤波器的自动调节参数以达最优化滤波的性能,提出了一种改进阈值提升小波结合自适应滤波的红外光谱去噪算法。该算法先通过改进阈值小波系数的提升小波去噪,在去噪的同时保留更多光谱特征信息,然后使用提升小波变换分解出的高频系数重构出噪声相关信号,将其作为最小均方误差自适应滤波器的参考输入进行二次滤波处理,最终获得的去噪信号很好的去除了与特征光谱频谱重叠的噪声信号。分别对人工添加噪声的标准红外光谱和合肥市市区上空实测开放光路红外光谱进行去噪处理,结果显示使用该算法处理后的光谱信噪比(SNR)较离散小波传统阈值去噪方法高出3db,均方根误差(RSME)平均减少30%左右,运行时间减少46%。表明该算法计算简单、运行速度快,对于大气环境监测实时消噪系统具有重要的实际应用意义。     

Pressure-induced phase transitions in single-crystalline Cu4Bi4S9 nanoribbons

In situ angle dispersive synchrotron X-ray diffraction and Raman scattering measurements under pressure are em- ployed to study the structural evolution of Cu4Bi4S9 nanoribbons, which are fabricated by using a facile solvothermal method. Both experiments show that a structural phase transition occurs near 14.5 GPa, and there is a pressure-induced re- versible amorphization at about 25.6 GPa. The electrical transport property of a single Cu4Bi4S9 nanoribbon under different pressures is also investigated.     

带除湿槽涡轮叶栅非平衡凝结流动数值研究

基于存在自发凝结的湿蒸汽两相流动,开发了基于汽液两相双流体模型和k-ε-k_p湍流模型的计算方法,并对喷管和二维叶栅进行数值验证,结果表明本文所开发的方法具有较高的可靠性。对某汽轮机末级除湿静叶考虑除湿槽结构的二维流场进行了数值研究,指出在叶片表面开设除湿槽结构,能够显著影响涡轮叶栅内的非平衡凝结流动。由于除湿槽对水滴的抽吸作用使得叶栅内成核率峰值降低,且变化幅度减小,因此成核过程更为稳定。除湿槽结构使得叶栅内部大水滴数目减少,尾迹区水滴平均半径减小,叶栅出口湿度下降。     

Collective Modes of a Quasi-Two-Dimensional Superfluid Fermi Gas in BCS-BEC Crossover

We investigate the collective modes of a quasi-two-dimensional （Q2D） superfluid Fermi gas in Bardeen-Cooper-Schrieffer Bose-Einstein condensation （BCS-BEC） crossover. For solving a generalized Gross-Pitaevskii equation by using a time-dependent variational method, we take a trial wavefunction with the form of hybrid Gaussianparabolic type, which not only reflects the Q2D character of the system and also allows an essentially analytical approach of the problem. We present a Q2D criterion that is valid for various superfluid regimes and displays clearly the relation between the maximum condensed particle number and the parameters of trapping potential as well as atom-atom interaction. We show that due to the small particle number in the Q2D condensate, the contribution to oscillating frequencies by the quantum pressure in the strong confinement direction is significant and hence a Thomas-Fermi approximation can not be used.