基于XP Embedded的嵌入式数字测厚仪设计与实现

如何提高开发效率,降低成本已经成为当前嵌入式系统开发方法研究中的热点。针对嵌入式数字测厚仪的研制要求,设计了基于普通PC机硬件平台,采用Windows XP Embedded进行嵌入式软件开发的技术路线。根据阳极溶解库仑法的原理,用PC机和自研的测厚采集卡实现了金属镀层厚度的测量、分析与数据存贮、打印等功能。实际开发和应用表明,这是一种高效、低成本的研发方法,此方法适用于类似的数字化仪器的开发研制。     

A new list compaction method

List compaction, or so-called ‘cdr-coding’, can greatly reduce the storage needs of list processing languages. However, existing methods do not perform well when several lists are being constructed simultaneously from the same heap, since the non-contiguous nature of the cells being allocated eliminates the opportunity for compaction. This situation arises not only in true parallel systems sharing a common memory, and sequential systems supporting multiple processes, but also quite often in purely sequential systems, where it is not uncommon to build several different lists simultaneously within a single loop. In this paper, a new list compaction method is presented that performs well during both sequential and ‘parallel’ list generation. The method is essentially a generalization of cdr-coding, in which lists are represented explicitly as linked vectors rather than implicitly as compacted memory. In addition, an encoding scheme is used that is as simple or simpler than all known encodings, and destructive operations are supported with no greater overhead than existing schemes. Performance figures in a simulated environment suggest that the strategy consistently performs better than conventional cdr-coding, with essentially the same complexity.     

Context-based embedded image compression using binary wavelet transform

Binary wavelet transform (BWT) has several distinct advantages over the real wavelet transform (RWT), such as the conservation of alphabet size of wavelet coefficients, no quantization introduced during the transform and the simple Boolean operations involved. Thus, less coding passes are engaged and no sign bits are required in the compression of transformed coefficients. However, the use of BWT for the embedded grayscale image compression is not well established. This paper proposes a novel Context-based Binary Wavelet Transform Coding approach (CBWTC) that combines the BWT with a high-order context-based arithmetic coding scheme to embedded compression of grayscale images. In our CBWTC algorithm, BWT is applied to decorrelate the linear correlations among image coefficients without expansion of the alphabet size of symbols. In order to match up with the CBWTC algorithm, we employ the gray code representation (GCR) to remove the statistical dependencies among bi-level bitplane images and develop a combined arithmetic coding scheme. In the proposed combined arithmetic coding scheme, three highpass BWT coefficients at the same location are combined to form an octave symbol and then encoded with a ternary arithmetic coder. In this way, the compression performance of our CBWTC algorithm is improved in that it not only alleviate the degradation of predictability caused by the BWT, but also eliminate the correlation of BWT coefficients in the same level subbands. The conditional context of the CBWTC is properly modeled by exploiting the characteristics of the BWT as well as taking advantages of non-causal adaptive context modeling. Experimental results show that the average coding performance of the CBWTC is superior to that of the state-of-the-art grayscale image coders, and always outperforms the JBIG2 algorithm and other BWT-based binary coding technique for a set of test images with different characteristics and resolutions.     

Thinning algorithms based on quadtree and octree representations

Thinning is a critical pre-processing step to obtain skeletons for pattern analysis. Quadtree and octree are hierarchical data representations in image processing and computer graphics. In this paper, we present new 2-D area-based and 3-D surface-based thinning algorithms for directly converting quadtree and octree representations to skeletons. The computational complexity of our thinning algorithm for a 2-D or a 3-D image with each length N is respectively O(N²) or O(N³), which is more efficient than the existing algorithms of O(N³) or O(N⁴). Furthermore, our thinning algorithms can lessen boundary noise spurs and are suited for parallel implementation.     

小波子带最优方向性选择和压缩感知的图像编解码

传统贝叶斯压缩感知方法所存在的局部优化问题导致了重构图像存在着较大的误差。本文提出一种基于小波自适应最优方向选择和压缩感知的图像编码方法,该方法依据图像小波变换的低频子带与高频子带所存在的相关性差异,对低频系数进行基于小波最优方向选择的编解码,以保证图像主要信息的重构质量;而针对高频子带的稀疏特性进行基于压缩感知的随机测量,以保证图像的编码效率。实验结果表明,与传统的压缩感知算法相比,本文所提出算法的解码图像具有更好的主观质量,同时在相同码率下解码图像的PSNR平均提高1~2dB。     

基于QT/Embedded的嵌入式煤矿电能监测

在煤矿中,电能质量是关乎生产、保障生产人员安全的重要因素,本文提出一种基于嵌入式处理器和linux系统的电能质量检测装置,快速准确的分析,显示,统计电能质量。     

A quadtree normalization scheme based on cyclic translations

An image can be represented by a compact and hierarchical structure, i.e. a quadtree. The storage requirements of an image constructed by a quadtree is highly sensitive to its position. Ang and Samet [Pattern Recognition Lett. 15(1), 57–63 (1994)] proposed an algorithm capable of normalizing a quadtree in O(s²log₂s) time and O(s²) space, where s is the length of the image grid, such that the number of nodes of the quadtree after normalization can be minimal. However, s is twice as long as the length of one side of the image to be normalized. In this study, we propose a normalization scheme based on cyclic translations. The time complexity and the space requirements of this scheme have four times less than those in Ang and Samet's case. In addition, no translation is necessary to fit the image into the northwest quadrant of the grid before the process of normalization. Also, this scheme can normalize a quadtree to obtain less node numbers than that of Ang and Samet. Furthermore, if the image's four corners have the same color, the amount of reduction for node number becomes larger after cyclic translations; it can occasionally reach to 75%. The analytical and empirical results demonstrate the advantages of this scheme.     

基于Qt/Embedded的嵌入式控制界面开发

作者通过结合Qt/Embedded的特性和优点,提出用Qt/Embedded实现风力发电控制系统的图形界面的思路和设计原则,重点介绍了在嵌入式Linux内核基础上Qt/Embedded的安装和编程过程.     

可移植的嵌入式WEB服务器软件设计

本文结合嵌入式系统的具体特点．着重探讨了软件在不同系统之间的可移植性问题，并在此基础上提供了一种可移植嵌入式WEB服务器软件的设计方法。     

基于入侵容忍的证书撤销列表机制研究

公钥基础设施(PKI)系统中,认证机构(CA)签名不易伪造,对基于证书撤销列表(CRL)的证书撤销系统的入侵通常是破坏系统的可用性和数据的完整性,针对这一特点,设计了入侵容忍CRL服务系统。系统利用冗余的多台服务器存储CRL,在进行多机之间的数据复制和使用时,采取随机选择主服务器的被动复制算法及选择最近更新的CRL简单表决算法。在实验给定的入侵攻击条件下,入侵容忍的CRL系统比无容忍系统的证书撤销查询正确率提高了近20%,但也增加了系统的开销。实验结果表明,适当地增加CRL服务器的数量能够提高证书撤销查询的正确率且控制系统的开销。     

嵌入式停车场管理系统

为改进基于PC的传统停车场管理系统工作于恶劣的环境中稳定性较差的问题,提出了一种基于嵌入式的停车场管理系统的设计方案。该方案结合MVC模式及QT/E技术实现了友好的嵌入式终端的界面交互;考虑到大型停车场多进多出的工作模式,使用心跳信号解决网络通信中常见的网络链接不稳定的状况;利用基于线程技术的数据采集有效保障数据采集的实时性和可靠性。经大量测试及实际使用证明,这种新型的嵌入式停车场管理系统,在工作稳定性上有大幅提高的同时使得停车场的成本也有所下降。     

组件式三层嵌入式数据库模型研究

近年来，随着移动设备设计制造技术和无线通信技术的发展，使得移动计算得到了大规模的应用。在进行移动计算应用开发过程中，嵌入式数据库的设计是一个关键环节，同时它也会遇到很多条件的限制。嵌入式数据库的设计需要在高效性，可移植性，可配置性，可扩展性等方面进行考虑。文章分析了目前数据库产品的设计特点，并针对嵌入式数据库的特点提出了一个组件式的三层设计模型。     

基于ARM的嵌入式智能前端的设计与实现

介绍了利用一种基于嵌入式操作系统的智能前端组建控制系统的基本原理和方法。详细分析了智能前端的硬件和软件实现。智能前端以AT91RM9200为核心,利用AT91RM9200强大的实时处理能力和众多外设接口实现对下位设备的控制,同时利用LXT971ALC实现与以太网的连接,通过标准的智能前端,现场各种分散的仪表,传感器就能方便地直接接入高速以太网,方便地组成智能分布式控制系统。     

嵌入式系统中SMTP协议的通讯实现

本文介绍了在网络时代的嵌入式系统发展状况．结合网络协议中SMTP协议自身的特点及其应用．提出了在嵌入式系统中提供SMTP支持的具体流程和方法．然后给出了SMTP代理在嵌入式系统下的一个具体实现．     

基于嵌入式WEB的AllLightSYS的设计实现

HTTP协议是目前流行的Web技术的主要协议，是Web浏览器和Web服务器之间进行通信的基础。本文首先对嵌入式系统从整体上进行了简析，说明了嵌入式系统不同于通用型计算机系统的特点和嵌入式系统应用的广泛性。然后从协议的角度出发论述了HTTP协议。最后介绍了一个基于嵌入式Web技术的AllLightSYS系统的设计与实现,重点阐述嵌入式服务器软硬件部分的设计思想和体系架构，并对关键技术进行了详细的介绍。     

基于嵌入式WEB的AllLightSYS的设计实现

HTTP协议是目前流行的Web技术的主要协议,是Web浏览器和Web服务器之间进行通信的基础。本文首先对嵌入式系统从整体上进行了简析,说明了嵌入式系统不同于通用型计算机系统的特点和嵌入式系统应用的广泛性。然后从协议的角度出发论述了HTTP协议。最后介绍了一个基于嵌入式Web技术的AllLightSYS系统的设计与实现,重点阐述嵌入式服务器软硬件部分的设计思想和体系架构,并对关键技术进行了详细的介绍。     

基于蓝牙技术的嵌入式工业诊断系统

本文介绍了一种采用蓝牙技术的嵌入式工业诊断系统，能实时采集终端监控信息回传到总控中心，实现了远程报警，和数据采集分析功能。文中对于蓝牙技术在工业环境里的实时性，稳定性作了基本的分析，同时试图探索一种平台独立的控制系统，增加系统的独立性和跨平台操作。文章最后探讨了蓝牙技术和TCP/IP协议栈的结合，嵌入式分布数据库的实现和管理。     

ARMv4指令集嵌入式微处理器设计

针对当前采用ARMv4指令集的嵌入式微处理器使用冯·诺依曼结构,数据和指令共用一条总线导致数据吞吐量降低的问题,设计了一款新架构微处理器。首先,采用哈佛结构独立的数据总线和指令总线,数据带宽提升一倍;其次,采用单周期32位乘法器,其计算速度是目前嵌入式乘法器计算速度的2倍;此外,利用资源共享,一个乘加器完成6种不同乘法和乘加指令,一个逻辑左移寄存器完成逻辑左移、逻辑右移、算术右移、循环右移4种功能。整个工程在Altera EP4CE30 FPGA芯片上进行物理验证。实验结果表明,通过改进,设计的嵌入式微处理器性能有所提升。     

基于uCLinux的嵌入式通讯的设计

介绍了如何在嵌入式操作系统uCLinux上进行嵌入设备通信程序的编写。同时介绍基于JUPITER高效双以太网处理器,并辅以LXT971A为以太网物理层接口的低功耗、高速硬件电路的设计;并实现了嵌入式设备的网络化信息通讯与控制。