嵌入式汽车轮胎规格号快速识别系统

针对汽车轮胎生产线检测的智能化管理问题,提出一种嵌入式系统以对轮胎规格号进行快速识别。对图像进行预处理,包括极坐标变换、双线性插值拉伸,利用大津法进行二值化,以连通域方法来提取规格号字符。采用基于统计的方法抽取轮廓特征进行规格号模式识别。系统硬件部分采用高速TMS320C6000系列DSP为核心的嵌入式硬件系统,使用参数预存储、软件流水线技术及双缓冲内存分配等优化方法。实验结果表明,该系统能快速有效地识别汽车轮胎规格号。     

基于Web日志的数据挖掘初探

Web日志挖掘是Web数据挖掘研究领域中一个最重要的应用方面。该文首先介绍了Web日志挖掘产生的背景,然后介绍了Web日志挖掘的基本概念,着重阐述了Web日志挖掘的预处理和日志挖掘算法两个关键技术,最后介绍了Web日志挖掘的应用,提出了其发展方向。     

软件框架技术在BOM组件开发中的应用

基于BOM的仿真系统开发具备诸多优点,但仿真模型组件开发及测试也存在辅助过程复杂、工作量大、协调困难等问题,为辅助仿真模型组件开发及测试,文章借助于软件框架技术,建立了一套配置简单、资源需求小的仿真组件开发辅助框架,通过该框架可减小组件开发中的迭代活动涉及范围,降低组件修改带来的附加工作量,加快仿真组件开发进度。     

等间距采样的高速数据采集系统设计

简单介绍通过对窄脉冲等间距采样来测试电缆故障的基本原理,分析其脉冲的特点和处理要求;采用FPGA和MSP430F149作为主控芯片,设计了单路多次低速数据采集系统;利用QuartusⅡ软件编写主控程序,并在Modelsim下进行仿真验证。实验结果表明,该系统方案切实可行,可有效解决电缆故障测距过程中的高精度数据采集问题。     

An adaptive signal-to-noise ratio estimator in mobile communication channels

Representing the reception condition directly, signal-to-noise ratio (SNR) is an important parameter in mobile propagation channels, and therefore is widely used in system performance evaluations and adaptive applications. Hence, this paper puts forward a frequency domain SNR estimator in mobile communications, where we exploit the signal model with the band-limited fading channel and the additive white Gaussian noise. With the above model, the noise power spectrum density can be estimated from the periodogram of channel-plus-noise signals, subsequently leading to our SNR estimation. Moreover, in order to degrade the intrinsic spectrum leakage of fast Fourier transform in periodogram calculation, the leakage expression is derived analytically and then an adaptive process is proposed to make a tradeoff between leakage reduction and noise smoothing. We verify our algorithm by simulations and observe high accuracy in a wide range of velocities and SNRs. Additionally, unlike the conventional work, the proposed estimator is not strictly based on the assumption of specific Doppler spectral shapes except for the requirement of the band-limited channel, hence it is robust to general mobile channels.     

A novel digital filter structure with minimum roundoff noise

In this paper, a novel structure is derived for efficient implementation of digital filters as well as minimizing the finite word length (FWL) errors. Such a structure is actually an improved version of that reported previously. The performance of this new structure and the famous normalized lattice structure are analyzed by deriving the corresponding expression for the roundoff noise gain. Design examples are presented to illustrate the behavior of the proposed structure and to compare it with some existing ones. It is shown that the proposed structure outperforms the others in terms of minimizing roundoff noise as well as implementation efficiency.     

A comparative study of two techniques for improving power‐handling capability of CMOS T/R switches

This article proposes an asymmetric topology for transmit/receive (T/R) switches and more importantly presents a comparative study of both LC‐tuned and resistive body‐floating techniques for improving the power‐handling capability of the T/R switches in the same 0.18‐μm triple‐well CMOS. It is shown from simulations and measurements that the switches adopting either technique achieve comparable performances. For instance, the switch employing the LC‐tuned body‐floating technique exhibits insertion loss of 1.5 dB, isolation of 23.5 dB, and power‐handling capability of 22.5 dBm at 5.2 GHz, whereas the switch using the resistive body‐floating technique exhibits insertion loss of 1.3 dB, isolation of 24 dB, and power‐handling capability of 22.2 dBm, respectively. Therefore, one can conclude that the asymmetric topology with the resistive body‐floating technique is more suitable for designing T/R switches for wireless local area network applications as it consumes smaller silicon area. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

A tree-based particle swarm optimization for multicast routing

QoS multicast routing is a non-linear combinatorial optimization problem. It tries to find a multicast routing tree with minimal cost that can satisfy constraints such as bandwidth, delay, and delay jitter. This problem is NP-complete. The solution to such problems is often to search first for paths from the source node to each destination node and then integrate these paths into a multicast tree. Such a method, however, is slow and complex. To overcome these shortcomings, we propose a new method for tree-based optimization. Our algorithm optimizes the multicast tree directly, unlike the conventional solutions to finding paths and integrating them to generate a multicast tree. Our algorithm also applies particle swarm optimization to the solution to control the optimization orientation of the tree shape. Simulation results show that our algorithm performs well in searching, converging speed and adaptability scale.     

基于PIC单片机的智能循迹小车设计

介绍了一种基于PIC单片机的智能循迹小车的硬件和软件设计。该智能循迹小车以PIC16F877A单片机为主控芯片,采用单光束红外光电传感器RPR221作为检测元件、恒压恒流桥式驱动芯片L298N作为小车驱动芯片,使小车能按预定的轨道稳定地行驶,能正确地识别路径、避障,速度和路程的显示较准确,具有一定的抗干扰能力。     

支持新型控制协议SIP的电力系统视频监控设计

针对电力系统视频监控工程的实际技术问题,采用嵌入式设备和基于网络分层的SIP管理架构,提出了一种支持新型控制协议SIP的电力系统视频监控设计,包括SIP的控制机制、基于SIP的监控系统结构、视频监控系统总体组成、硬件设计、软件设计和实验结论等;该系统的各成员之间可以通过组播或单播的方式进行交互,并在域内处理大量的信令信息和媒体流信息,具有扩展性、智能性、灵活性、自主性和互操作性等多种优良特性;经测试指标符合技术规范,实现了电力系统视频监控管理及控制的基本和扩展功能。