汽车被动无钥门禁系统（PKE）研究

免持式被动无钥门禁（PKE）正迅速成为汽车远程无钥门禁应用的主流,并成为新车型的普遍选项。该方法无需用手按发送器按钮来锁上或打开车门,只要拥有一个有效的应答器就可方便地进出车辆。结合微芯公司PIC16F639微控制器的特性．设计出相应的无线收发通信系统。     

Microchip推出用于无线识别的独立模拟前端器件

Microchip(美国微芯科技公司)发布其首款适用于智能化125 kHz低频无线识别应用的独立模拟前端(AFE)器件。 MCP2030这一新款模拟前端器件配备三通道的应答器,具有可编程天线调节功能,调制深度低至8％。该器件是被动无钥门禁、胎压监测系(TPMS)、数据采集及其他无线识别应用的理想解决方案。     

Microchip推出用于无线识别的独立模拟前靖器件

Microchip（美国微芯科技公司）发布其首款适用于智能化125kHz低频无线识剐应用的独立模拟前端（AFE）器件。MCP2030这一新款模拟前端器件配备三通道的应答器，具有可编程天线调节功能，调制深度低至8％。该器件是被动无钥门禁、胎压监测系统（TPMS）、数据采集及其他无线识别应用的理想解决方案。     

基于Microchip公司的被动门禁系统分析与设计

被动无钥门禁(PKE)作为新一代的遥控加密技术,是在传统的遥控车门开关(RKE)的基础上发展而来,正在逐步发展壮大且将会成为主流.文中剖析Microchip公司基于PIC16F639的PKE解决方案,结合作者设计体会,分析整个设计参考,展现整个设计理念,充分利用硬件与软件优势以及独特的用户身份的识别和自动开锁车门.Microchip公司的PKE方案的显著特点是采用KEELOQ加密技术,以及应答器中采用集成模拟前置终端,很大程度上降低了成本.基于该PKE设计参考研发的产品将有很好的应用前景.     

机场交通出入口 门禁控制的金字塔

自9．11之后，随着恐怖威胁的加大，人们对于安全的需求从没有像今天这样强烈。机场作为一个重要的公共活动场所，门禁控制系统成为安全防范的第一道防护。本文试用一个金字塔来表示门禁控制级别，探讨通过综合金字塔的级别来实现整个门禁控制系统的无缝对接。     

2009年门禁产品发展趋势——技术革新进行时 周边产品放光彩

2008年,基于TCP／IP方式门禁系统展现出强劲态势,系统集成化也继续推进;而同时,手机SIM卡集成门禁功能等新产品也令人耳目一新,可看出各门禁厂家除在原有基础上开发新产品外,也不断进行技术革新。相信随着硬件产品的逐渐成熟,以及越来越多大项目的出现,门禁软件以及针对专门领域应用的产品和集成方案成为门禁市场新的需求点,如何在这种新的需求面前转变思路,开发新产品,对厂家是一大考验。     

基于人体感应的门禁控制系统研究

安全可靠、方便的门禁控制系统与人民生活水平的提高息息相关,近几年门禁控制技术发展迅速。通过对指纹门禁控制系统、人脸门禁控制系统和语音门禁控制系统的深入研究,提出了人体多器官感应的门禁控制系统,提高了门禁控制系统的安全可靠性能。     

可证明安全的异构无线传感器秘钥管理协议

认证和秘钥协商协议是解决无线传感器网络中设备安全通信的主流方法,而目前主流的无线传感器网络秘钥协商协议考虑的场景为对等节点之间的认证和协商,存在计算量高、通信效率低的问题。针对以上问题,提出了适用于异构无线传感器网络中的认证与秘钥管理协议,通信终端节点(L节点)双方首先与各自所在簇的管理节点(H节点)协商会话秘钥,若未通过身份认证,则拒绝L节点接入网络,解决了大多数协议缺少应对拒绝服务攻击的问题;然后借助通信路径所经过的H节点转发会话秘钥协商信息,完成通信双方端到端的会话秘钥协商,使得协议具有安全网关和访问控制的能力。该协议还支持对被捕获节点的节点注销,并减少对其他通信链路安全性的影响。基于求解椭圆曲线上的离散对数问题和Diffie-Hellman问题的困难性假设,在随机预言机模型中证明了该方案可以满足前向安全、抗秘钥泄露伪装攻击、未知秘钥共享安全、无秘钥托管、已知秘钥安全等更完整的安全属性,与已有文献相比,所提协议在应对拒绝服务攻击上具有最低的计算开销,整体计算量和通信量适中。     

Atmel推出拥有卓越RF性能的智能RF接收器IC系列

Atmel公司推出专为汽车和智能射频（RF）市场设计的全新系列低功耗、高性能RF接收器。凭借极低的功耗、极高的灵敏度和卓越的带外阻塞性能,三款新的设备（ATA5781、ATA5782和ATA5783）将成为众多汽车应用的理想选择,其中包括：遥控无钥匙门禁系统（RKE）、被动门禁启动系统（PEG）／被动门禁、被动启动系统（PEPS）、遥控启动系统（RS）和胎压监测系统（TPMS）。     

任凭风浪起“稳”坐钓鱼船 7款门禁／停车场引导系统实地测试专辑

“任凭风浪起‘稳’坐钓鱼船”，正如标题所言，门禁求的就是一个“稳”，能够稳稳当当的“守住”大门，时刻维护好各系统之间的平稳，即为好门禁。正是如此，门禁已不是单纯的门与钥匙的管理，它早已超越了过去，逐渐发展成一整套完善的出入管理系统。并且随着全球安防网络化已经成为不可逆推的事情，摄像机从模拟到网络、存储设备从DVR到NVR都是一个非常大的革新，门禁也是如此。     

Residual-based specification of a hidden random field included in a hierarchical spatial model

A method for specifying a hidden random field (HRF) included in a hierarchical spatial model is proposed. In hierarchical models of interest the first stage describes, conditional on a realization of the HRF, a response variable which is observable on a continuous spatial domain; the second stage models the HRF which reflects unobserved spatial heterogeneity. The question which is investigated is how can the HRF be modeled, i.e. specified. The method developed to address this question is based on residuals obtained when the base model, i.e. the hierarchical model in which the HRF is assumed constant, is fitted to data. It is shown that the residuals are linked with the HRF, and the link is used to specify the HRF. The method is applied to simulated data in order to assess its performance, and then to real data on radionuclide concentrations on Rongelap Island.     

Residual-based specification of a hidden random field included in a hierarchical spatial model

A method for specifying a hidden random field (HRF) included in a hierarchical spatial model is proposed. In hierarchical models of interest the first stage describes, conditional on a realization of the HRF, a response variable which is observable on a continuous spatial domain; the second stage models the HRF which reflects unobserved spatial heterogeneity. The question which is investigated is how can the HRF be modeled, i.e. specified. The method developed to address this question is based on residuals obtained when the base model, i.e. the hierarchical model in which the HRF is assumed constant, is fitted to data. It is shown that the residuals are linked with the HRF, and the link is used to specify the HRF. The method is applied to simulated data in order to assess its performance, and then to real data on radionuclide concentrations on Rongelap Island.     

基于WebService的高校应用集成

目前高校中都存在业务系统异构难于集成的问题.根据这个问题,提出了基于WebService的高校应用集成的解决方案.该方案主要是把高校中现存的业务系统通过重新改造成WebService,从而利用WebService良好的低耦合性和标准性,实现应用集成.在WebService的基础上,给出了高校应用集成的SOA架构;给出了该架构下每个模块的技术实现,其中遗留业务系统的改造是最困难的部分;最后在WSAD上实现了一个业务模块的改造.在技术上实现了基于WebService的高校应用集成,并成功实现了一个业务模块,从而证明了基于WebService的高校应用集成的可行性,并给出了下一步的改进方向.     

Is the unfolding of the group discussion off-pattern? Improving coordination support in educational forums using mobile devices

A forum is a valuable tool to foster reflection in an in-depth discussion; however, it forces the course mediator to continually pay close attention in order to coordinate learners’ activities. Moreover, monitoring a forum is time consuming given that it is impossible to know in advance when new messages are going to be posted. Additionally, a forum may be inactive for a long period and suddenly receive a burst of messages forcing forum mediators to frequently log on in order to know how the discussion is unfolding to intervene whenever it is necessary. Mediators also need to deal with a large amount of messages to identify off-pattern situations. This work presents a piece of action research that investigates how to improve coordination support in a forum using mobile devices for mitigating mediator’s difficulties in following the status of a forum. Based on summarized information extracted from message meta-data, mediators consult visual information summaries on PDAs and receive textual notifications in their mobile phone. This investigation revealed that mediators used the mobile-based coordination support to keep informed on what is taking place within the forum without the need to log on their desktop computer.     

Improving network security through port switching

The latest range of network performance improvement is the use of switching technologies to isolate traffic from various systems. This is achieved by placing a system on a device called a switching bridge which, in turn, isolates traffic by only allowing packets to be sent to the port on which the system is located when a packet is actually addressed to the system in question or when the message is a group or broadcast message that would be sent to all nodes. In a typical LAN environment, systems on a network segment ‘see’.     

领域本体中概念间语义相关度的概率估计

根据贝叶斯定理提出一种衡量领域本体中概念间语义相关度的概率模型。该模型定义在不同语义关系之上,基于极大似然估计法利用语义距离来对语义关系进行参数估计。并在此基础给出一种计算任意两个概念之间语义相关度的方法。公开数据集上的实验结果表明该方法估计出的概念语义相关度具有相当的有效性,应用在语义查询扩展中可明显提高检索效果。     

Signal detection for bilinear systems

The injection operator used by McKean to construct Brownian paths on a Lie group is employed to formulate a class of signal detection problems on matrix Lie groups. The hypotheses that the signal is absent and present in the observation on a Lie group are described by a pair of bilinear matrix Ito equations. The injection operator is shown to be almost surely bijective and its inverse is constructed. This bijection enables us to do detection and estimation of processes taking values on a Lie group in a finite dimensional linear space-the Lie algebra. In fact, bilinear detection on Lie groups (“locally linear spaces”) is in essence equivalent to linear detection on linear spaces. A likelihood ratio formula for bilinear matrix Ito equations is thus derived as a function of up-dated observation.     

一种基于双层窗口的概念漂移数据流分类算法

数据流中概念漂移问题的研究已成为近年来流数据挖掘领域的研究热点之一. 已有的研究工作多依据单窗口中错误率的变化来检测概念漂移,难以适应不同类型的漂移. 为此, 本文提出一种新的基于双层窗口机制的数据流分类算法(Double-windows-based classification algorithm for concept drifting data streams, DWCDS),该算法采用随机决策树模型构建集成分类器, 利用双层窗口机制周期性地检测滑动窗口中流数据分布的变化,并动态地更新模型以适应概念漂移. 分析与实验结果表明: 该算法可以快速有效地跟踪检测含噪数据流中的概念漂移,且抗噪性能与分类精度显著提高.     

PCA for large data sets with parallel data summarization

Parallel processing is essential for large-scale analytics. Principal Component Analysis (PCA) is a well known model for dimensionality reduction in statistical analysis, which requires a demanding number of I/O and CPU operations. In this paper, we study how to compute PCA in parallel. We extend a previous sequential method to a highly parallel algorithm that can compute PCA in one pass on a large data set based on summarization matrices. We also study how to integrate our algorithm with a DBMS; our solution is based on a combination of parallel data set summarization via user-defined aggregations and calling the MKL parallel variant of the LAPACK library to solve Singular Value Decomposition (SVD) in RAM. Our algorithm is theoretically shown to achieve linear speedup, linear scalability on data size, quadratic time on dimensionality (but in RAM), spending most of the time on data set summarization, despite the fact that SVD has cubic time complexity on dimensionality. Experiments with large data sets on multicore CPUs show that our solution is much faster than the R statistical package as well as solving PCA with SQL queries. Benchmarking on multicore CPUs and a parallel DBMS running on multiple nodes confirms linear speedup and linear scalability.