河南宝丰和新郑出土硅酸盐制品的无损分析研究

无损分析是文物样品研究的重要内容,研究中采用便携式能量色散型X射线荧光光谱仪(pXRF)和激光拉曼光谱仪(LRS),对河南宝丰和新郑出土的21件战国晚期到汉代的硅酸盐制品进行了化学成分分析和微区物相分析。依据化学成分分析结果,将样品划分为铅钡硅酸盐玻璃、钾硅酸盐玻璃、釉砂和铅钡釉砂四类分别进行讨论,并对样品的着色机理进行了初步探讨;利用激光拉曼光谱在部分蜻蜓眼和圆环珠蓝色颜料中检测到了中国蓝(BaCuSi₄O₁₀)、中国紫(BaCuSi₂O₆)和中国深蓝(BaCu₂Si₂O₇),同时成功确定了部分样品中存在石英、方解石、碳酸铅、煅棕土、绿土等多种物相;结合考古研究资料,对这些样品的来源进行了简要讨论,其中本实验铅钡硅酸盐玻璃、钾硅酸盐玻璃耳珰和铅钡釉砂为我国自制,而另外1件釉砂可能属于舶来品,反映了我国古代中原各地区间,以及中原与西域间有着广泛的文化技术交流。便携式能量色散型X射线荧光光谱仪和激光拉曼光谱仪的相互结合,能够提供硅酸盐制品的有效化学成分和结构信息,在文物科学分析中显示出特有的优势,为其考古研究提供有益的信息。     

Effect of lateral structure parameters of SiGe HBTs on synthesized active inductors

The effect of lateral structure parameters of transistors including emitter width, emitter length, and emitter stripe number on the performance parameters of the active inductor(AI), such as the effective inductance Ls, quality factor Q,and self-resonant frequency ω_0 is analyzed based on 0.35-μm Si Ge Bi CMOS process. The simulation results show that for AI operated under fixed current density JC, the HBT lateral structure parameters have significant effect on Ls but little influence on Q and ω_0, and the larger Ls can be realized by the narrow, short emitter stripe and few emitter stripes of Si Ge HBTs. On the other hand, for AI with fixed HBT size, smaller JCis beneficial for AI to obtain larger Ls, but with a cost of smaller Q and ω_0. In addition, under the fixed collector current IC, the larger the size of HBT is, the larger Ls becomes, but the smaller Q and ω_0 become. The obtained results provide a reference for selecting geometry of transistors and operational condition in the design of active inductors.     

A technique for simultaneously improving the product of cutoff frequency–breakdown voltage and thermal stability of SOI SiGe HBT

The product of the cutoff frequency and breakdown voltage( fT×BVCEO) is an important figure of merit(FOM) to characterize overall performance of heterojunction bipolar transistor(HBT). In this paper, an approach to introducing a thin N+-buried layer into N collector region in silicon-on-insulator(SOI) Si Ge HBT to simultaneously improve the FOM of fT×BVCEOand thermal stability is presented by using two-dimensional(2D) numerical simulation through SILVACO device simulator. Firstly, in order to show some disadvantages of the introduction of SOI structure, the effects of SOI insulation layer thickness(TBOX) on fT, BVCEO, and the FOM of fT×BVCEOare presented. The introduction of SOI structure remarkably reduces the electron concentration in collector region near SOI substrate insulation layer, obviously reduces fT, slightly increases BVCEOto some extent, but ultimately degrades the FOM of fT×BVCEO. Although the fT,BVCEO, and the FOM of fT×BVCEOcan be improved by increasing SOI insulator Si O_2 layer thickness TBOXin SOI structure, the device temperature and collector current are increased due to lower thermal conductivity of Si O_2 layer, as a result, the self-heating effect of the device is enhanced, and the thermal stability of the device is degraded. Secondly, in order to alleviate the foregoing problem of low electron concentration in collector region near SOI insulation layer and the thermal stability resulting from thick TBOX, a thin N+-buried layer is introduced into collector region to not only improve the FOM of fT×BVCEO, but also weaken the self-heating effect of the device, thus improving the thermal stability of the device. Furthermore, the effect of the location of the thin N+-buried layer in collector region is investigated in detail. The result show that the FOM of fT×BVCEOis improved and the device temperature decreases as the N+-buried layer shifts toward SOI substrate insulation layer. The approach to introducing a thin N+-buried layer into collector region provides an effective method to improve SOI Si Ge HBT overall performance.     

石墨微粒柱电化学预富集-火焰原子吸收联用测定镉

以石墨微粒柱电极为工作电极,对溶液中痕量镉进行电化学预富集、溶出,并用火焰原子吸收分光光度法在线测定。极大的提高了测试灵敏度,降低检出限达1—2个数量级,富集倍数可达754倍。并就支持电解质种类和浓度,富集流速、电压,溶出液流速、电压,pH值对测定的影响作了深入的研究。     

传声器阵列波束比判决语音增强方法

针对单一波束形成器难以深度抑制空间相干干扰的问题,提出了一种综合了最小方差无畸变响应波束形成器与对称子阵延时求和波束形成器的语音增强方法。定义了一种波束输出比因子,根据该因子在目标声区域和干扰声区域的幅值变化,给出了采样协方差矩阵对角加载量的调整方法,并进一步利用该因子在后滤波环节对空间干扰进行判决滤波。文中对判决滤波时的上限阈值和下限阈值的实时更新方法给出了说明。所提出的算法能进一步抑制空间干扰和噪声,且可满足实时需要。在传声器圆阵上的实验表明,该方法在输出信干噪比及语音质量上,均优于经典对角加载算法及采样协方差矩阵扫描重构算法。      

串列仿生鱼自主游动的数值模拟研究

采用自适应网格下的ghost-cell浸没边界方法,数值模拟了两条串列仿生鱼在相同摆频条件下的自主游动,并通过引入节能效率的概念分析了串列游动中的节能效果。通过与相同参数下单条仿生鱼自主游动的比较,发现串列仿生鱼的自主游动速度要大于单条鱼的速度。下游鱼的阻力会增加,但功耗会减少,表明下游鱼从上游鱼的尾涡中吸收了能量,达到了节能的效果。当水平间距较小时,下游鱼会对上游鱼产生一定的反推作用,从而使其阻力减小。结果还表明,高推进效率并不意味着高节能效率,从整体平均节能效果来看,反相位游动时节能效果比同相位时显著,平均节能效率达到22.4%。     

基于INS/ILS/RA组合导航的自动着陆系统

针对民航机精密进近着陆过程容易受地场环境、电磁干扰等空间噪声和接收机噪声的影响,对波束误差信号进行滤波相位滞后的问题,提出基于INS/ILS/RA组合导航的自动着陆系统(ALS)。该系统将仪表着陆系统(ILS)及无线电高度表(RA)和惯性导航系统(INS)输出的位置之差作为量测,运用卡尔曼滤波器进行估计,将组合导航系统的输出航迹角及纵向轨迹角替代波束偏差,分别送入横纵向控制回路。仿真结果表明,INS/ILS/RA组合位置解算方位角偏差精度优于0.3°,下滑角偏差精度优于0.2°。该系统可显著改善波束误差控制信号的动态品质,降低噪声影响,提高ILS自动进场着陆控制回路的稳定性和闭环性能。     

区域水土资源可持续利用评价的脉冲耦合神经网络(PCNN)模型模糊算法的构建与应用——以中国三江平原为例

针对三江平原水土资源区域特点,选择了20个指标,建立了水土资源评价指标体系和标准;对脉冲耦合神经网络模型(PCNN模型)进行了改进,提出基于模糊算法的F-PCNN模型,动态阈值等于区域水土资源评价标准的等级范围,省略了不必要的参数,减少了模型的复杂度,并应用于三江平原水土资源评价中.分析结果表明三江平原创业农场水土资源可持续利用评价等级为Ⅱ级,说明水土资源开发和利用较合理,可持续发展能力较强.应用结果说明F-PCNN模型在三江平原水土资源可持续利用评价中是可行的,既拓展了PCNN的应用领域,又为解决水土资源的分类、评价问题提供了新的思路和方法.     

无催化法制备ZnO纳米针的结构及光学特性

采用无催化脉冲激光沉积(PLD)方法,在InP(100)衬底上生长纳米ZnO针状结构。采用扫描电子显微镜(SEM)、X射线衍射(XRD)以及光致发光(PL)谱等对ZnO纳米针的形貌、晶体结构和光学特性表征。SEM图像观察到ZnO纳米针状结构具有一定的取向性。XRD测试在2θ=34.50°处观测到强烈的ZnO(002)衍射峰,证实ZnO纳米针具有较好的c轴择优取向。室温PL谱在379nm处观察到了较强的自由激子发射峰(半峰全宽为13.5nm),而微弱的深能级跃迁峰位于484nm,二者峰强比值为11∶1,表明生长的纳米ZnO结构具有较高的光学质量。     

基于角谱法的振幅型光子筛的设计和分析

对光子筛的聚焦成像原理作了分析,并用平面波角谱方法对光子筛聚焦成像进行了数值模拟.模拟结果表明,光子筛聚焦具有提高分辨率和抑制高级衍射的优点.在理论分析和计算机模拟的基础上,设计并制作了Fresnel波带片、未平滑处理和平滑处理后的光子筛.用波长为532 nm激光光源对波带片和光子筛聚焦光斑进行检测.结果表明,光波通过光子筛聚焦后的光斑比波带片的光斑更细,成像对比度更高.