基于ARM的CAN总线电缆沟道监测系统的设计

提出了一种基于ARM的CAN总线电力电缆沟道监测系统,给出系统整体结构,详细介绍了系统硬件设计方案,提出了一种基于高性能处理器ARM的CAN节点设计方法。最后详细介绍了基于μC／OS—II的CAN通信的软件实现过程。     

"两成两力"建设评估标准的结构分析与运行算法

从我军现有装备成建制、成系统以形成作战能力和保障能力("两成两力")建设评估标准出发,总结并规范其标准结构中存在的问题,建立评估指标树,包括节点位置和节点关系及节点属性描述.再根据属性值从底层指标开始,依次逐层计算出叶及各枝节点的得分值,从而计算出评估的最后得分值,由此完成计算机伪码算法.     

Performance evaluation of CSMA/ID MAC protocol for IP over WDM ring networks

In this paper, a packet pre‐classification media access control protocol based on a carrier sense multiple access with idle detection (CSMA/ID) scheme is investigated for supporting IP packets over all‐optical WDM ring networks. The purpose of the protocol is to increase throughput and to decrease the packet transmission delay of IP packets over optical networks in a metropolitan area network. This protocol avoids both packet collision and packet fragmentation. In order to improve the utilization of the network, the packets transmitted from a local area network are first pre‐classified into various class queues of an access point (AP) according to their length. After checking the available space based on the wavelength received by the receivers of the AP, the packets in the queues are transmitted. An analytical model is developed to evaluate the performance of the protocol, with simulation results showing good network efficiency. The proposed network has short‐term variations that introduce unfairness conditions. This problem could be overcome by assigning a quota on individual queues to allow all queues fair access. Copyright © 2008 John Wiley & Sons, Ltd.     

SQLSERVER数据同步机制的研究与应用

该文研究了一种基于SQLSERVER复制方法的数据同步机制,并将其应用于某大型征稽管理系统,实现了省到市、到县所、到站点这四级之间数据变化的实时同步。通过设置动态筛选,使用存储过程,配置触发器和调度作业,实现了全省近300站点同步更新各自站点数据,减少了数据传输量,提高了数据同步的传输效率、灵活性、安全性和准确性。     

Parameter learning of personalized trust models in broker-based distributed trust management

Distributed trust management addresses the challenges of eliciting, evaluating and propagating trust for service providers on the distributed network. By delegating trust management to brokers, individual users can share their feedbacks for services without the overhead of maintaining their own ratings. This research proposes a two-tier trust hierarchy, in which a user relies on her broker to provide reputation rating about any service provider, while brokers leverage their connected partners in aggregating the reputation of unfamiliar service providers. Each broker collects feedbacks from its users on past transactions. To accommodate individual differences, personalized trust is modeled with a Bayesian network. Training strategies such as the expectation maximization (EM) algorithm can be deployed to estimate both server reputation and user bias. This paper presents the design and implementation of a distributed trust simulator, which supports experiments under different configurations. In addition, we have conducted experiments to show the following. 1) Personal rating error converges to below 5% consistently within 10,000 transactions regardless of the training strategy or bias distribution. 2) The choice of trust model has a significant impact on the performance of reputation prediction. 3) The two-tier trust framework scales well to distributed environments. In summary, parameter learning of trust models in the broker-based framework enables both aggregation of feedbacks and personalized reputation prediction.

彩色显微骨髓细胞图像噪声的自适应矢量中值滤波

提出了一种基于彩色图像噪声的自适应矢量中值滤波方法,可根据噪声干扰的情况自动选择滤波窗口的大小.首先,检测3×3窗口中矢量中值与其他矢量之间的平均距离,然后根据这个平均距离的大小来判断选择3×3窗口,或5×5窗口,或1×1窗口.当选择1×1窗口时,意味着滤波输出就是原图像的像素值.模拟实验显示,应用自适应矢量中值滤波器能有效地滤除彩色显微骨髓细胞图像的噪声,并能较好地保护边缘和细节,其性能较一般的矢量中值滤波方法要好.     

基于AMESim的滑移装载机自动调平系统

通过分析滑移装载机工作系统的动作循环,详细阐述了调平阀的工作机理,并从理论角度论述了其实现流量分配比功能的基本原理。在对比试验与仿真数据的基础上,建立了可靠的调平系统仿真模型。研究表明:按比例增大固定节流孔和可调节流孔的直径,有利于提高系统的动态特性;此外,适当减小卸荷阀内阻尼孔的直径,或增加稳定阻尼孔的直径可以降低系统增益,提高系统动态响应性能。     

浅谈PSPICE在高频教学中的应用

实际教学中,学生普遍反映高频电子线路课程较难理解和掌握,文章对此进行了简单的分析。为了改进教学方法,提高效率,教学中引入电子设计自动化工具PSPICE,并以丙类谐振功率放大器和乘法器应用为例,以验证性实验、启发性实验、综合性实验三种方式。介绍了PSPICE在“高频”教学中的应用,总结了应用CAD工具的优点和局限性,提出将CAD工具与理论教学、实际实验有机组合提高教学质量的观点。实践证明,教学效果较好。     

A low glitch 10-bit 75-MHz CMOS video D/A converter

A low glitch 10-bit 75-MHz CMOS current-output video digital-to-analog Converter (DAC) for high-definition television (HDTV) applications is described. In order to achieve monotonicity and low glitch, a special segmented antisymmetric switching sequence and an innovative asymmetrical switching buffer have been used. The video DAC has been fabricated by using 0.8 μm single-poly double-metal CMOS technology. Experimental results indicated that the conversion rate is above 75 MHz, and nearly 50% of samples have differential and integral linearity errors less than 0.24 LSB and 0.6 LSB, respectively. The glitch has been reduced to be less than 3.9 pV·s and the settling time within ±0.1% of the final value is less than 13 ns. The video DAC is operated by a single 5 V power supply and dissipates 1.70 mW at 75 MHz conversion rate (140 mW in the DAC portion). The chip size of video DAC is 1.75 mm×1.2 mm (1.75 mm×0.7 mm for the DAC portion)