Deciding determinism of caterpillar expressions

Caterpillar expressions have been introduced by Brüggemann-Klein and Wood for applications in markup languages. Caterpillar expressions provide a convenient formalism for specifying the operation of tree-walking automata on unranked trees. Here we give a formal definition of determinism of caterpillar expressions that is based on the language of instruction sequences defined by the expression. We show that determinism of caterpillar expressions can be decided in polynomial time.     

FPSFI:一种基于LLVM架构的驱动错误隔离机制

内核安全维系着应用程序的正常运行,而内核错误却仍被周期性地发现,且多数错误是由模块加载机制将存在问题的设备驱动引入内核所致.基于UVM编译器基础架构,提出FPSFI驱动错误运行时隔离机制,使驱动错误隔离机制分解为涉敏函数注册、驱动错误定位与检测函数的插装等三个模块,有效地阻止了由内核API完整性缺失所导致的权限非法提升以及内存空间被多次释放等常见驱动错误.相比于之前的方法,FPSFI将错误分析与定位实现在编译器后端,减少了人工添加检测代码的工作量,而检测函数的单独实现与编译,使得隔离机制对内核接口的依赖程度有所降低.基于Linux平台的测试结果表明,FPSFI能够有效阻止两类典型的驱动错误;FPSFI对后端编译器改动所造成的时间开销比为18.7％;对网络模块的压力测试结果显示,FPSFI不会显著影响CPU利用率以及TCP吞吐量,UDP吞吐量下降17％.     

单机非接触式IC卡门禁系统的改进设计研究

门禁系统是在传统门锁基础上发展起来的智能管理系统.文章介绍了非接触IC卡和基于校园"一卡通"中的单机式门禁系统.从学校的应用中发现了新的单机门禁系统解决方案,用UML简单阐述了新的系统的管理软件的模型.     

基于SOPC的GPS信息加密传输系统

设计了一个GPS信息加密传输系统,用于车辆、人员等重要移动目标的远程监控。该系统主要由一台中心计算机和一组终端模块组成,前者负责定位信息的接收、处理、显示以及密钥分发等系统管理任务,后者安装在被监控的移动目标上,负责定位及其它监控信息的加密传输,中心计算机与终端模块之间采用CDMA进行无线通信。终端模块利用商用GPS接收模块实现定位信息采集,采用基于Alera FPGA的SOPC技术,实现了整个终端模块的控制和数据加解密。     

数据网格信息服务体系的研究与设计

网格信息服务是网格中间件的核心部分之一,提供各种分布式网格资源的静态与动态信息。现有的网格中间件几乎都是针对计算网格设计的,它们所提供的信息服务不能胜任数据网格的要求。论文主要对数据网格中的信息服务体系进行研究和设计。     

Adaptive Bas‐relief Generation from 3D Object under Illumination

Bas‐relief is designed to provide 3D perception for the viewers under illumination. For the problem of bas‐relief generation from 3D object, most existing methods ignore the influence of illumination on bas‐relief appearance. In this paper, we propose a novel method that adaptively generate bas‐reliefs with respect to illumination conditions. Given a 3D object and its target appearance, our method finds an adaptive surface that preserves the appearance of the input. We validate our approach through a variety of applications. Experimental results indicate that the proposed approach is effective in producing bas‐reliefs with desired appearance under illumination.     

Event‐triggered control design for nonlinear systems with actuator failures and uncertain disturbances

Traditional adaptive event‐triggered design methods compensated for the event‐triggered error are not direct, and the stability analysis of resulting close‐loop systems is rather complicated. To alleviate the above restrictions, we propose a direct and simple event‐triggered co‐design method to solve the tracking control problem for parameter strict‐feedback systems with actuator faults and uncertain disturbances. By introducing a compensating terms in a smooth function form of a conventional control law and certain positive integrable functions, the effects of actuator faults and event‐triggered error can be compensated completely. Such a direct design method has the following features: (i) a direct compensation of the event‐triggered error is achieved without introducing any extra design parameters; (ii) it is not necessary to know any bound information on the parameters of event‐triggered threshold, and global asymptotic tracking control of the overall closed‐loop system is achieved; and (iii) the resulting stability criteria of the proposed event‐triggered control design are much simpler and easier to fulfill by virtue of the introduced co‐design method. Simulations are then carried out to validate the proposed schemes.     

3D‐printed cylindrical Luneburg lens antenna for millimeter‐wave applications

A 3D‐printed cylindrical Luneburg lens antenna working at 26 GHz is proposed in this article. The antenna consists of a feeding waveguide, a 3D‐printed cylinder, and a pair of printed metal grids which are stuck on the side faces of the cylinder. 3D‐printed structure ensures the convenience for processing and structural integrity of the Luneburg lens. Hole drilling technology is utilized for the design of the cylindrical lens. In the E‐plane, conversion of spherical waves into planar waves is achieved based on the gradient refractive index which is realized by the gradient equivalent relative dielectric constant. The main part of the lens contains a hole drilling region to realize the desired equivalent permittivity from 1.23 to 2, while another gradual‐thickness region realize the permittivity ranges from 1.23 to 1. H‐probe method is utilized for the optimization of the gradual‐thickness region in this article. And for the H‐plane, with the grids, H‐field distribution is optimized compared with the Luneburg lens antenna without the loading grids. Thus, the side lobe level (SLL) in H‐plane could be reduced. Meanwhile, a narrower half power beamwidth (HPBW) in H‐plane will be obtained due to the metal grids. Experiment results illustrate the feasibility and validity of the proposed 3D‐printed cylindrical Luneburg lens antenna.     

基于面阵CCD的相机自动调焦技术

为满足摄影分辨力的要求 ,在航空相机拍摄过程中 ,镜头位置要随着摄影距离的改变相应调整。线阵CCD交汇测量能准确测定点目标的距离 ,但对于面目标测量难度较大 ,若用面阵CCD替代线阵CCD ,并利用小波变换获取的图像边缘特征 ,自动识别相同点目标在不同CCD面上的成像位置 ,可实现面目标距离精确测量和相机焦距的自动调整。