一种软件代码精细分析技术

精细分析对提高关键软件的安全非常重要,并因计算量大而需要自动化.本文基于J M Voas的Fault/Failure概念模型及其PIE分析,提出一个实用的软件代码精细分析技术和工具.文中描述了软件代码精细分析的全过程,重点讲述“自动分析记录”的工作流程及执行、感染和传播这三个关键分析的概念性算法,并给出了工具的框架图解.此外还提出粒度可调思想,能调节分析的精度和范围,较好地解决了Fault/Failure模型的限制,拓展了用途.最后本文给出了一些具体的应用思路,如放置警报器、评估可靠性、配置资源、设计测试实例等,以及对面向对象软件测试的启发.     

Stability Testing of Two-Dimensional Discrete-Time Systems by a Scattering-Type Stability Table and Its Telepolation

Stability testing of two-dimensional (2-D) discrete-time systems requires decision on whether a 2-D (bivariate) polynomial does not vanish in the closed exterior of the unit bi-circle. The paper reformulates a tabular test advanced by Jury to solve this problem. The 2-D tabular test builds for a real 2-D polynomial of degree (n ₁, n ₂) a sequence of n ₂ matrices or 2-D polynomials (the 2-D table). It then examines its last polynomial - a 1-D polynomial of degree 2n ₁ n ₂ - for no zeros on the unit circle. A count of arithmetic operations for the tabular test is performed. It shows that the test has O(n ⁶) complexity (assuming n ₁ = n ₂ = n)- a significant improvement compared to previous tabular tests that used to be of exponential complexity. The analysis also reveals that, even though the testing of the condition on the last polynomial requires O(n ⁴) operations, the count of operations required for the table's construction makes the overall complexity O(n ⁶). Next it is shown that it is possible to telescope the last polynomial of the table by interpolation and circumvent the construction of the 2-D table. The telepolation of the tabular test replaces the table by n ₁ n ₂ + 1 stability tests of 1-D polynomials of degree n ₁ or n ₂ of certain form. The resulting new 2-D stability testing procedure requires a very low O(n ⁴) count of operations. The paper also brings extension for the tabular test and its simplification by telepolation to testing 2-D polynomials with complex valued coefficients.     

Effect of plasma process-induced damage on bias temperature instability of MOSFETs

For a surface-channel n-MOSFET and a buried-channel p-MOSFET, the effect of plasma process-induced damage on bias temperature instability (BTI) was investigated. The gate oxide thickness, t_ox, of the test MOSFETs was 2.0, 3.0, or 4.5 nm. The shifts of threshold voltage V_th and of linear drain current I_dlin were measured after applying a BTI stress at a temperature of 125 °C. The measured shifts of V_th and I_dlin indicate that BTI on ultra-thin gate CMOS devices appears only in the form of SiO₂/Si interface degradation, and that the positive BTI for the n-MOSFET as well as the negative BTI for the p-MOSFET is important for the reliability evaluation of CMOS devices. Because of positive plasma charging to the gate, a protection diode was very efficient at reducing BTI for the p-MOSFET, but it was much less effective for the n-MOSFET.     

敏感元件在有线电视器件中的应用

阐述敏感元件的基本概念及其在有线电视网络器件中的几种典型应用,首先介绍敏感材料的基本类型和今后的发展趋势,然后详细介绍目前比较典型的几种敏感元件在开关稳压电源、Cable Modem、双向放大器、彩电消磁、程控交换机、光工作站中的应用。     

3G流媒体测试方法研究

介绍移动流媒体技术的基本特征,阐述3GPP PSS规范的相关协议。为了解决移动流媒体播放时发生的问题,首先应该得到它的量化描述。提出一种移动流媒体测试方法,包括测试系统的系统架构、逻辑结构和测试内容。     

异构网络环境下的并行程序可达性测试算法

针对不确定性并行程序难于测试的问题,分析了并行程序消息传递行为与网格环境中网络性能约束之间的关系,在经典可达性测试算法的基础上,提出了新的限定性可达性测试算法,称为基于网络性能约束的可达性测试算法。本算法在考虑网络性能约束的基础上,只对发生频率高的执行路径进行测试,缩减了待测试路径的数量,提高测试效率,在此基础上尽可能保证测试的完全性。     

测控系统中的软件抗干扰技术

测控系统在使用中存在着大量的干扰源,严重影响了系统运行的可靠性。通常使用硬件抗干扰措施与软件抗干扰措施来抑制系统中出现的各种干扰。软件抗干扰措施是硬件抗干扰措施的一个补充和延伸,具有简单、灵活、方便、耗费硬件资源少及容易实现等特点。软件抗干扰技术的使用会显著提高系统的可靠性。本文着重讨论了测控系统中的软件抗干扰技术。     

基于DS18B20可编程温度传感器的最小温控系统的设计与实现

以AT89C52单片机为开发平台,通过对单总线可编程温度传感器DS18B20的特性、内部结构、工作流程进行深入的研究,结合相应的软、硬件设计,在此基础上开发了一种多用途的最小温度控制系统。与传统装置相比,具有结构简单,测温精度高、应用面广等特点。     

混频相控阵聚焦特征的研究

混频相控阵作为超声相控阵中的一种新方法，在声场聚焦和偏转都有突出表现。文中对其在聚焦过程中的聚焦特征及相关因素与常规同频相控进行对比分析，得出混频相控阵有利于提高焦区的声能密度，信噪比和轴向分辨率；同时给出了如何优化选择阵列各阵元相应的激发频率。这对改善超声诊断的成像质量和提高聚焦治疗的能量密度等有重要意义。     

MEMS开关封装结构热形变对芯片性能的影响

模拟了处在一定功率密度或不同温度下封装结构贴片的形变引起的X波段MEMS开关芯片的形变,从而导致的开关芯片性能的变化。用Coventor软件模拟出在开关衬底为200μm,贴片处功率密度为300pW/μm2时,开关芯片的形变量为0.142μm;开关衬底为300μm,温度为373K时,开关芯片的形变量为0.791μm。进一步用HFSS模拟出开关的插入损耗在中心频率10GHz处由封装前的0.042dB和0.022dB变化为封装后的0.078dB和0.024dB。