距离向DBF鄄SAR 自适应SCORE 处理研究

针对AD 数据的扫描接收法(SCORE)处理中权系数不易计算准确和加权处理过程复杂的问题,提出了基于AD 数据的自适应SCORE 处理算法,该算法既可直接利用同一波门的数据估计通道间的数字波束形成(DBF)权系数,也可先将多通道数据分组并时变加权,再自适应估计分组数据的DBF 权系数,多通道数据通过与权系数相乘和累加完成SCOR处理。相比其他算法,该算法具有权系数精度高、加权处理简单和运算量小的特点,适合长短脉冲DBF-SAR 的SCORE 处理,实测数据的成像结果验证了算法的有效性。     

高功率光纤激光器用20/400双包层掺镱光纤

采用改进化学气相沉积结合溶液掺杂法制造出了掺镱石英光纤预制棒,预制棒轴向上芯径波动小于5%,折射率差波动小于8%。研磨加工后拉制出20/400双包层掺镱光纤,光纤纤芯不圆度为2%,芯包同心度偏差为0.87 μm。双包层掺镱光纤在1095 nm的包层损耗为2.1 dB/km。采用拉制的掺镱双包层光纤作为直接振荡结构全光纤化激光器的增益光纤实现了1195 W的1080 nm激光输出,斜率效率达82%。     

红外探测器用陶瓷/可伐合金钎焊技术研究

当前制冷型红外探测器所使用的金属材料、陶瓷材料的工作温度为80 K左右,其钎焊焊缝要求与常规钎焊焊缝存在很大的差异。本文对当前陶瓷/金属材料的钎焊方法进行了整理,使用AgCuTi钎料进行了钎焊工艺实验,实现了可伐合金/陶瓷(蓝宝石)材料直接钎焊(无金属化)。实验后进行了焊缝气孔率检测、抗温度冲击实验(333～77 K)。实验结果显示该种焊接方法满足制冷型焦平面探测器对可伐合金/陶瓷(蓝宝石)材料钎焊的要求,该工艺方法制备的焊接件可在超低温环境中长期服役。     

基于正交设计的Si基复合衬底优化工艺试验

在正交设计的基础上,通过一系列工艺测试实验,研究了MEE外延温度、MEE退火温度、CdTe外延温度、CdTe退火温度对Si基复合衬底的两个关键质量因素FWHM和表面粗糙度的影响。通过统计技术对测得的实验数据进行了方差分析,结果表明,CdTe退火温度是影响FWHM的关键因子,MEE退火温度和CdTe外延温度对Ra值来说影响是显著的。通过该系列实验得到最优的外延工艺条件。     

基于FSA的卫星任务规划流程定制平台设计

随着卫星任务规划资源种类和数量的逐渐增加,基于固定规划流程的卫星任务规划系统凸显出多项弊端,为解决这些问题,通过分析卫星任务规划流程的特点,提出了基于可定制有限状态自动机(FSA)模型的任务规划流程定制平台系统。利用有限状态自动机模型,将卫星任务规划流程中的各业务环节看成该模型中的不同状态,通过状态设置完成流程的定制和调整,以实现对卫星任务规划流程的灵活定制。经过对实验系统的运行结果分析表明,该平台设计可以有效地降低任务规划流程调整的复杂程度,提升卫星任务规划系统的可扩展性。     

数字图像自相关函数的优化逼近模型

将复杂的非平稳随机信号划为分段平稳随机信号进行处理,以信号自相关函数反映信号特征。而自相关函数是数字图像频谱分析的基础,可作为图像清晰度评价函数,并有助于寻找有效的信号正交基。为精确有效地表示分段平稳随机信号,在分析ARMA模型、分段平稳随机过程和Markov过程的基础上,建立多参数的自相关函数估计模型,其提高了逼近效果,可适应变化复杂的非平稳信号。计算机仿真表明,该模型逼近误差显著下降。     

“In-VM”模型的隐藏代码检测模型

Security tools are rapidly developed as network security threat is becoming more and more serious. To overcome the fundamental limitation of traditional host based anti malware system which is likely to be deceived and attacked by malicious codes, VMM based anti malware systems have recently become a hot research field. In this article, the existing malware hiding technique is analyzed, and a detecting model for hidden process based on “In VM” idea is also proposed. Based on this detecting model, a hidden process detection technology which is based on HOOK SwapContext on the VMM platform is also implemented successfully. This technology can guarantee the detecting method not to be attacked by malwares and also resist all the current process hiding technologies. In order to detect the malwares which use remote injection method to hide themselves, a method by hijacking sysenter instruction is also proposed. Experiments show that the proposed methods guarantee the isolation of virtual machines, can detect all malware samples, and just bring little performance loss.     

Effects of post-lift-off annealing conditions on contact oxidation of Ti–Au top-contacts in In-Sn–Zn–O TFT

Thin film transistors (TFT) with an indium based mixed oxide semiconductor are investigated for titanium–gold top-contacts. It is noticed that upon post annealing, in order to remove chemical residuals from top-contact lift-off steps, oxidation of titanium occurs depending on the annealing conditions. Mobility of the TFT is strongly affected by contact oxidation arising from this post lift-off annealing process. Oxidation of the top-contact is facilitated by adsorbed surface oxygen or out-diffusing oxygen from the semiconductor depending on the post lift-off annealing conditions. A passivation layer that binds effectively to surface vacancies and removes adsorbed oxygen species from the semiconductor surface is demonstrated. The combinations of this passivation layer with relatively low temperature and short post lift-off annealing in an oxygen deficient environment result in significantly reduced contact oxidation and subsequently better transistor performance. Contact resistance as low as 90 Ω cm and mobility as high as 5.3 cm²/V s are obtained for solution processed mixed metal oxide semiconductor in top-contact geometry.     

Computational studies on the radiative and nonradiative processes of luminescent N-heteroleptic platinum(II) complexes

Three N-heteroleptic Pt(II) complexes, [Pt(C^C)(O^O)] [O^O = acetylacetonate, C^C = 1-phenyl-1,2,4-triazol-5-ylidene (1), C^C = 4-phenyl-1,2,4-triazol-5-ylidene (2), C^C = 2-phenylpyrazine (3)] have been investigated with density functional theory (DFT) and time-dependent density functional theory (TDDFT). The radiative decay rate constants of complexes 1–3 have been discussed with the oscillator strength (f_n), the strength of spin–orbit coupling (SOC) interaction between the lowest energy triplet excited state (T₁) and singlet excited states (S_n), and the energy gaps between E(T₁) and E(S_n). To illustrate the nonradiative decay processes, the transition states between triplet metal-centered (³MC) and T₁ states have been optimized and were verified with the calculations of vibrational frequencies and intrinsic reaction coordinate (IRC). In addition, the minimum energy crossing points (MECPs) between ³MC and ground states (S₀) were optimized. At last, the potential energy curves relevant to the nonradiative decay pathways are simulated. The results show that complex 3 has the biggest photoluminescence quantum yield because the complex 3 has the biggest radiative decay rate constant and the smallest nonradiative decay rate constant in complexes 1–3.     

利用简单电阻偏置网络实现的高线性度电流驱动型无源混频器

A high linearity current communicating passive mixer including the mixing cell and transimpedance amplifier(TIA) is introduced.It employs the resistor in the TIA to reduce the source voltage and the gate voltage of the mixing cell.The optimum linearity and the maximum symmetric switching operation are obtained at the same time.The mixer is implemented in a 0.25μm CMOS process.The test shows that it achieves an input third-order intercept point of 13.32 dBm,conversion gain of 5.52 dB,and a single sideband noise figure of 20 dB.