基于BIST的动态可重构FPGA的时延故障测试方法

FPGA市场已经进入极速发展时代,不同的销售商已向市场投入更多更快的FPGA器件。随着FPGA器件的迅速发展,FP-GA的密度和复杂程度也越来越高,使大量的故障难以使用传统方法进行测试,因此,对FPGA器件的故障测试和故障诊断方法进行更全面的研究具有重要意义。为此重点研究了动态重构FPGA及其基本结构、特点;在此基础上探讨了基于BIST技术的FPGA时延故障测试方法,并成功应用于Lattice ORCA 2C系列FPGA中。实验证明,该BIST方法是可行且有效的,并且不需要昂贵的ATE设备。     

基于RTX的复杂虚拟试验分层实时网络环境研究

复杂实时仿真系统中不同层次对实时性、可靠性要求各不相同;网络和操作系统是该类系统环境的重要组成部分;针对硬件在回路试验的实时需求,提出了基于RTX下的反射内存网的半实物接入网络,构建了基于RT-TCP/IP的虚拟试验局域网;其操作系统层面,设计为弱实时任务在Windows内核上运行,而强实时任务分布在RTX内核之上;文中对各层面的实时性进行了测试,分析了层面间的实时性约束;结合某飞行试验系统的虚拟试验,给出了具体的设计方案,满足了应用中不同实时性的要求。     

直升机操纵台的BIT功能设计

为了提高系统的易测试性,保证飞行安全,在该直升机操纵台硬件设计中,针对各个功能模块的特点,相应地采用了多种BIT(Build-in Test,机内测试)技术,如余度BIT、环绕BIT等技术,并在微控芯片软件中嵌入了自检测模块,全面完整地实现了系统的自检测;同时利用扩展flash存储芯片实时保存系统运行数据和测试信息,可通过串口上传至上位机,为故障分析提供了便利;采用Visual C++编程语言,结合专家系统开发了一套上位机检测软件,用于操纵台故障的智能诊断。     

FTPA: Supporting Fault-Tolerant Parallel Computing through Parallel Recomputing

As the size of large-scale computer systems increases, their mean-time-between-failures are becoming significantly shorter than the execution time of many current scientific applications. To complete the execution of scientific applications, they must tolerate hardware failures. Conventional rollback-recovery protocols redo the computation of the crashed process since the last checkpoint on a single processor. As a result, the recovery time of all protocols is no less than the time between the last checkpoint and the crash. In this paper, we propose a new application-level fault-tolerant approach for parallel applications called the Fault-Tolerant Parallel Algorithm (FTPA), which provides fast self-recovery. When fail-stop failures occur and are detected, all surviving processes recompute the workload of failed processes in parallel. FTPA, however, requires the user to be involved in fault tolerance. In order to ease the FTPA implementation, we developed Get it Fault-Tolerant (GiFT), a source-to-source precompiler tool to automate the FTPA implementation. We evaluate the performance of FTPA with parallel matrix multiplication and five kernels of NAS Parallel Benchmarks on a cluster system with 1,024 CPUs. The experimental results show that the performance of FTPA is better than the performance of the traditional checkpointing approach.     

An EM approach to mineral analysis using natural gamma rays

We describe here a method for the analysis of materials on a conveyor belt using the natural gamma spectra collected with a BGO (Bismuth Germanate) gamma ray detector. This detector collects gamma ray emissions from the Potassium (K), Uranium (U), and Thorium (Th) atoms in the materials. Based on these data, and using a Poisson model for the data generation, a statistical model is proposed and an approximate maximum likelihood (ML) technique based on the expectation-maximization (EM) algorithm is then used to estimate the amount of each of the three elements in the material. The statistical model is further refined to incorporate parameters of drift in the detector and an estimation technique for this is developed and tested against real data. The Cramér–Rao lower bounds for the estimators are calculated.     

Design and analysis of a self-tuning feedback controller for the Internet

Active queue management (AQM) is an effective method used in Internet routers for congestion avoidance, and to achieve a tradeoff between link utilization and delay. The de facto standard, the random early detection (RED) AQM scheme, and most of its variants use average queue length as a congestion indicator to trigger packet dropping. This paper proposes a novel packet dropping scheme, called self-tuning proportional and integral RED (SPI-RED), as an extension of RED. SPI-RED is based on a self-tuning proportional and Integral feedback controller, which considers not only the average queue length at the current time point, but also the past queue lengths during a round-trip time to smooth the impact caused by short-lived traffic dynamics. Furthermore, we give theoretical analysis of the system stability and give guidelines for selection of feedback gains for the TCP/RED system to stabilize the average queue length at a desirable level. The proposed method can also be applied to the other variants of RED. Extensive simulations have been conducted with ns2. The simulation results have demonstrated that the proposed SPI-RED algorithm outperforms the existing AQM schemes in terms of drop probability and stability.     

Reliability-based design optimization of problems with correlated input variables using a Gaussian Copula

The reliability-based design optimization (RBDO) using performance measure approach for problems with correlated input variables requires a transformation from the correlated input random variables into independent standard normal variables. For the transformation with correlated input variables, the two most representative transformations, the Rosenblatt and Nataf transformations, are investigated. The Rosenblatt transformation requires a joint cumulative distribution function (CDF). Thus, the Rosenblatt transformation can be used only if the joint CDF is given or input variables are independent. In the Nataf transformation, the joint CDF is approximated using the Gaussian copula, marginal CDFs, and covariance of the input correlated variables. Using the generated CDF, the correlated input variables are transformed into correlated normal variables and then the correlated normal variables are transformed into independent standard normal variables through a linear transformation. Thus, the Nataf transformation can accurately estimates joint normal and some lognormal CDFs of the input variable that cover broad engineering applications. This paper develops a PMA-based RBDO method for problems with correlated random input variables using the Gaussian copula. Several numerical examples show that the correlated random input variables significantly affect RBDO results.     

视觉游戏与设计创意

"视觉游戏"并非是艾尔·塞克尔所研究的视觉科学中的幻觉现象,而是一种设计理念。这种理念不仅体现在设计师追求设计乐趣、享受设计过程的态度上,而且体现在设计师对于挑战"规则"、突破"传统"、寻求自由轻松的设计氛围的追求中。现代平面设计具有较强的视觉游戏特征,主要体现在趣味性、游戏性、无序性、偶然性这四个方面。当平面设计以"视觉游戏"的形式展现时,它在图形、文字和编排的创意与表现上都呈现出新的面貌。     

基于MATLAB的地震正演模型实现

人工合成地震正演模型是进行三维模型计算的基础,在地震勘探领域具有重要意义.针对地震勘探原理,作者运用MATLAB强大数学计算和图像可视化功能,对一个三层介质模型制作二维人工合成地震记录.文章说明地震记录形成的物理机制,介绍了地质模型的构造及参数选择,针对具体地质模型制作合成地震记录,成功验证了褶积模型原理.     

Detection of urinary biomarkers for early diagnosis of acute renal allograft rejection by proteomic analysis

Acute allograft rejection has been recognized as a major impediment to improved success in renal transplantation. Timely detection and control of rejection are very important for the improvement in long-term renal allograft survival. Thus, biomarkers for early diagnosis of acute rejection are required urgently to clinical medication. This study seeks to search for such biomarker candidates by comparing patients' pre-treatment urinary protein profiling with their post-treatment urinary protein profiling. A total of 15 significantly and consistently down-regulated protein candidates were identified. Among them, alpha-1-antichymotrypsin precursor (AACT), tumor rejection antigen gp96 (GP96) and Zn-Alpha-2-Glycoprotein (ZAG) were selected for further analysis. The results indicated that Western Blot assay of AACT, GP96 and ZAG had advanced the diagnosis time of acute renal rejection by 3 days, compared with current standard clinical observation and laboratory examination. Furthermore, the double-blind detection revealed that the accuracy, sensitivity and specificity of the diagnosis of acute renal rejection of AACT, GP96 and ZAG were 66.67%/100%/60%, 83.33%/100%/80% and 66.67%/100%/60%, respectively, and 100%/100%/100% in combination. In conclusion, urinary protein AACT, GP96 and ZAG could be a set of potential biomarkers for early non-invasive diagnosis of the acute rejection after renal transplantation.