DSP系统抗干扰技术的研究

可靠性设计是一项系统工程,DSP系统的可靠性必须从软件、硬件以及结构设计等方面全面考虑.本文以TI公司的DSP芯片TMS320LF2407A为例详细介绍了DSP系统在工业现场中的干扰和这些干扰产生的影响,以及硬件和软件抗干扰技术的应用.     

SoC中低峰值功耗的BIST调度算法

本文提出了一种系统芯片(SoC)中用于降低内建自测试(Built-in Self-test，BIST)峰值功耗的调度算法。首先本文提出了基于扫描BIST的精简功耗模型，在此模型的基础上，提出了通过调整扫描周期和扫描起动时间的办法来避免过高的SoC测试峰值功耗。实验结果表明，该算法可以有效地避免BIST并行执行可能带来的过高峰值功耗。     

半导体器件欧姆接触中的扩散阻挡层

为提高半导体器件欧姆接触的可靠性，一般要在金属化系统中加扩散阻挡层。本文介绍了扩散阻挡层的种类及其特性，并进行了比较和讨论。最后给出了在实际成功应用的例子。     

Si/SiGe/Si HBT频率特性的解析模型与模拟

用解析的方法模拟了T＝300K和77K时，fT和fmax与集电极电流密度Jc的关系，在大电流下考虑了异质结势垒效应的影响。模拟结果和用数值方法以及实验所得到的结果一致。同时，还建立了与之相应的Si／SiGeeb异质结和SiGe／Sibc异质结电容模型。     

Order statistic filter banks

Filter banks play a major role in multirate signal processing where these have been successfully used in a variety of applications. In the past, filter banks have been developed within the framework of linear filters. It is well known, however, that linear filters may have less than satisfactory performance whenever the underlying processes are non-Gaussian. We introduce the nonlinear class of order statistic (OS) filter banks that exploit the spectral characteristics of the input signal as well as its rank-ordering structure. The attained subband signals provide frequency and rank information in a localized time interval. OS filter banks can lead to significant gains over linear filter banks, particularly when the input signals contain abrupt changes and details, as is common with image and video signals. OS filter banks are formed using traditional linear filter banks as fundamental building blocks. It is shown that OS filter banks subsume linear filter banks and that the latter are obtained by simple linear transformations of the former. To illustrate the properties of OS filter banks, we develop simulations showing that the learning characteristics of the LMS algorithm, which are used to optimize the weight taps of OS filters, can be significantly improved by performing the adaptation in the OS subband domain.     

Thermal Conductivity Prediction of Thermally Conductive,Electrically Insulating Materials under van der Waals Interactions

The thermal transport phenomenon in small-scale heterogeneous composites is essentially controlled by van der Waals interactions. In this article, thermal conductivity of nanocomposites with 33 wt% crystallized silicon dioxide is four times higher than that of epoxy (EP) resin composites. Nanocomposites with 33 wt% boron carbide exhibit seven times higher thermal conductivity than pure EP. Pal and Lewis-Nielsen multiscale models were used to infer that distance-associated van der Waals interactions vary between composites with different weight fractions. Such variation consequently affects the thermal conductivity of the composites. Scanning electron microscope images of crystallized silicon dioxide/EP composites provide evidence of our reasonable and accurate inferences with regard to the thermal conduction mechanism. Experimental values confirm that the Pal model is superior to the Lewis-Nielsen model. The observed enhancement in thermal conductivity indicates important implications for the development of highly and thermally conductive electrically insulating materials. Results of this study can also be considered to improve modeling for thermal conductivity under van der Waals interactions.     

Diffused Phase Transition Boosts Thermal Stability of High‐Performance Lead‐Free Piezoelectrics

High piezoelectricity of (K,Na)NbO₃ (KNN) lead‐free materials benefits from a polymorphic phase transition (PPT) around room temperature, but its temperature sensitivity has been a bottleneck impeding their applications. It is found that good thermal stability can be achieved in CaZrO₃‐modified KNN lead‐free piezoceramics, in which the normalized strain d ₃₃* almost keeps constant from room temperature up to 140 °C. In situ synchrotron X‐ray diffraction experiments combined with permitivity measurements disclose the occurrence of a new phase transformation under an electrical field, which extends the transition range between tetragonal and orthorhombic phases. It is revealed that such an electrically enhanced diffused PPT contributed to the boosted thermal stability of KNN‐based lead‐free piezoceramics with high piezoelectricity. The present approach based on phase engineering should also be effective in endowing other lead‐free piezoelectrics with high piezoelectricity and good temperature stability.     

开环双波段人眼视网膜成像液晶自适应光学系统设计

设计了一套基于开环双波段模式的人眼视网膜成像液晶自适应光学系统。该光学系统分别采用夏克-哈特曼波前传感器和液晶空间光调制器来探测和校正波前畸变。探测波段采用830nm近红外光,成像波段采用790nm近红外光。采用开环模式以提高光能利用率和系统的稳定性,采用双波段模式以增大视场。新加入了瞳孔监控子系统和响应矩阵测量子系统,使系统更加灵活方便。介绍了系统的关键参数,并通过ZEMAX软件对光学系统进行模拟分析,认为系统可以达到接近衍射极限的效果。传递函数MTF@50lp/mm达到0.25(对应视网膜上3μm),满足设计要求。     

一种基于TLM超混沌细胞神经网络图像加密新算法

混沌对初值敏感的特性使得它适合于数据加密。以4 阶CNN 模型为基础,提出了一种新的超混沌细胞神经网络图像加密算法。算法分为置乱和扩散二个阶段,复合混沌映射用于生成置乱阶段控制参数,用以置乱图像行列之间的高度互相关像素。在扩散阶段,使用不同初始状态和参数的复合混沌映射生成高阶混沌细胞神经网络的初始条件,以生成扩散阶段的密钥流。算法的已知明文和选择明文攻击、密钥空间和直方图的仿真实验均取得了良好的结果。与其他相关算法相比,该算法具有密钥敏感性和抗攻击性强的优点,适用于图像加密。     

大功率激光器阵列光场分布测试方法的研究

针对大功率半导体激光器阵列难以进行光场分布测试评价的问题,设计了大功率激光器光场分布测试系统。从测试系统探测器的抗损伤阈值方面,分析了对激光衰减的比例要求,提出了几种衰减的方法,设计了低透射系数高抗激光损伤的衰减方案,并进行逐一的测试比较,得到了理想的衰减效果。结合测试系统要求,完成了大功率半导体激光器光场分布的测试与评价。