预烧工艺对MgTiO3系MLCC瓷料性能的影响

以Mg(OH)2,TiO2,CaCO3和ZnO为主要原材料,采用不同预烧工艺合成了MgTiO3主晶相材料。研究发现,快速升温到高温区(1150℃),然后降低温度至1000℃并保温4h所得的MgTiO3主晶相材料,为结构均匀、近似球形的颗粒,用其制备的MLCC瓷料,比表面积为5.5～6.5m2/g,分散性好。这种瓷料适合制造薄介质膜,制得的MLCC具有优良的介电性能,其绝缘强度E大于1.243V/m,tanδ小于1.3×10–4,εr为15.0～15.5。     

S频段锁相频率合成器的设计

介绍了小数式锁相频率合成器的设计方法及相关理论,分析了影响锁相环相位噪声的主要因素并设计了环路滤波器和Wilkinson功率分配器。由实验结果可知,小数式锁相频率合成器具有很好的相位噪声和较高的频率分辨率。     

一种通用的并联反馈式微波介质振荡器设计方法

介绍了并联反馈式介质振荡器的设计方法和相关理论,分析了影响介质振荡器性能的一些参数。采用高频路仿真和场仿真软件对13.20 GHz的介质振荡器进行设计,仿真结果表明,在偏离载频10 kHz处输出信号相噪为-113.6 dBc/Hz,功率为 10.026 dBm。     

Insight into the Inclusion Complexation of Fluconazole with Sulfonatocalix[4]naphthalene in Aqueous Solution,Solid-State,and Its Antimycotic Activity

The study aims to assess the interaction between fluconazole and sulfonatocalix[4]naphthalene towards enhancing its dissolution performance and antimycotic activity. A solubility study was carried out at different pH conditions, and the results revealed the formation of a 1:1 molar ratio fluconazole-sulfonatocalix[4]naphthalene inclusion complex with an A_L type phase solubility diagrams. The solid powder systems of fluconazole-sulfonatocalix[4]naphthalene were prepared using kneaded and co-evaporation techniques and physical mixtures. DCS, PXRD, TGA-DTG, FT-IR, and in vitro dissolution performance characterize the prepared systems. According to physicochemical characterization, the co-evaporation approach produces an amorphous inclusion complex of the drug inside the cavity of sulfonatocalix[4]naphthalene. The co-evaporate product significantly increased the drug dissolution rate up to 93 ± 1.77% within 10 min, unlike other prepared solid powders. The antimycotic activity showed an increase substantially (p ≤ 0.05, t-test) antimycotic activity of fluconazole co-evaporate mixture with sulfonatocalix[4]naphthalene compared with fluconazole alone against clinical strains of Candida albicans and Candida glabrata. In conclusion, sulfonatocalix[4]naphthalene could be considered an efficient complexing agent for fluconazole to enhance its aqueous solubility, dissolution performance, and antimycotic activity.     

结构光测量中的高精度相位误差补偿算法

在模拟分析投影仪伽马非线性对相位误差影响的基础上,提出一种直接分析投影光栅特征并建立相位误差查找表的算法.对相位误差进行补偿.该算法通过分析一组投射到标准白色平板上的光栅图像,确定光栅相位值与相位误差的对应关系,并量化存储在一个查找表中,测量过程中使用查找表对相位误差进行补偿.实验结果表明.该方法可大大降低由投影仪伽马非线性引起的相位误差,系统测量精度达到0.043 mm,比误差补偿前提高了5.6倍.     

多通道星载合成孔径雷达姿态误差影响分析与补偿

针对高分辨率条件下,多通道星载合成孔径雷达(Synthetic Aperture Radar,SAR)姿态控制误差对成像质量影响问题开展研究.首先建立多通道姿态控制误差数学模型,在此基础上推导了姿态控制误差与接收天线相位中心位置、控制误差角度以及天线下视角等参数的数学表达式,定量化地分析了该误差对成像质量的影响方式与影响大小,并提出一种高效精确的误差补偿方法.最后,计算机仿真实验验证了本补偿方法的正确性及有效性.     

一种无片外电容LDO的稳定性分析

电路如果存在不稳定性因素,就有可能出现振荡。本文对比分析了传统LDO和无片电容LDO的零极点,运用电流缓冲器频率补偿设计了一款无片外电容LDO,电流缓冲器频率补偿不仅可减小片上补偿电容而且可以增加带宽。对理论分析结果在Cadence平台基上于CSMC0.5um工艺对电路进行了仿真验证。本文无片外电容LDO的片上补偿电容仅为3pF,减小了制造成本。它的电源电压为3.5～6 V,输出电压为3.5 V。当在输入电源电压6 V时输出电流从100μA到100mA变化时,最小相位裕度为830,最小带宽为4.58 MHz     

高性能数字频率合成器的设计与实现

通过对直接数字频率合成技术的研究,采用单片机AT89S51控制DDS芯片AD9854设计出一种高性能直接数字频率合成器。该数字频率合成器采用并行通信的方式传输控制字,通过改变控制字来改变输出频率,得到所需频率的正弦波。软件上采用菜单式、全部键盘控制方式。用4×4矩阵键盘控制,进行功能选择以及设置频率、幅度和相位控制字。界面显示用带中文字库的液晶TS-12864显示,实现了良好的人机交互,系统操作使用方便。用单片机控制DDS数字芯片实现的数字频率合成器,有着比模拟频率合成器更好的抗干扰性、频率分辨率和频谱纯度,同时有着更小的体积。系统经测试得到所需频率的正弦波,数字频率合成器设计成功。     

单脉冲飞秒激光作用下晶态GeSb2Te4相变薄膜的非晶化过程

利用飞秒激光的抽运探测技术，研究了单脉冲飞秒激光作用下GeSb2Te4相变薄膜的非晶化过程，测量了相变薄膜的时间分辨光学显微图。所研究的系统为多层薄膜结构100 nm ZnS-SiO2/ 35 nm GeSb2Te4 /120 nm ZnS-SiO2/0.6 mm ，飞秒激光的脉冲宽度为108 fs，波长为800 nm。实验发现相变薄膜从晶态至非晶态的相转变过程可以在 2.6 ns内完成。讨论了相变薄膜的厚度对系统的热传递、快速凝固过程的影响，分析了相关热过程和热效应，解释了抽运探测实验数据，并探讨了单脉冲飞秒激光诱导相变薄膜非晶化的机制。     

Progress in CdZnTe substrate producibility and critical drivers of IRFPA yield originating with CdZnTe substrates

With the goal of maximizing the yield of infrared focal plane arrays (IRFPAs), Santa Barbara Research Center’s (SBRC) Infrared Materials Producibility Program (IRMP) has focused on assessing and improving the quality, yield, and throughput of CdZnTe substrates. A baseline detector lot was fabricated to identify the critical drivers of IRFPA yield coming from the substrates and to evaluate the quality and yield of the current vendor base for CdZnTe substrates. Substrate induced defects and impurities that can potentially affect device performance and operability were carefully mapped out in detail on 44 × 67 mm² size substrates, received from IRMP substrate vendors as well as SBRC. This paper will report on the correlations found between this substrate characterization data base and the IRFPA level defect distributions. Key results from these correlation studies are: (1) extended defects found on the substrates with the Nakagawa etch correlated well with responsivity reduction in the final IRFPA; (2) cross-hatch patterns that were evident in the responsivity map correlated well with similar features seen by x-ray topography on LPE double layers; and (3) a possible correlation of device performance (leakage current at 78K) with copper and lithium impurities in the substrate. Recent initiatives toward improving the quality and yield of the substrate growth process have focused on improving purity in the pre-growth charge preparation, modification of growth parameters to reduce defects and scaling up of the vertical Bridgman growth process from its current 67 mm diameter boule size to 92 mm diameter boules. Promising initial results from the large diameter boule growth process will be shown. The 92 mm diameter CdZnTe boule (6 kg charge) shows two predominant single crystal grains encompassing 75% of boule volume. Defect characterization of boules grown under baseline and modified conditions is discussed.