Application of Wireless Local Area Network Technology in Mobile Robot for Finned Tube Inspection

This paper introduces a novel robot for outer surface inspection of boiler tubes. The paper describes the hardware system, wireless communication strategy, communication procedure and system software of the robot. The WLAN technology is used in the robot. It solves the problem of shielding generated by iron boiler and 11Mbps bandwidth made it possible for video and control stream real-time transmit within the same channel. Though TCP/IP protocol is robust, serial server is a transparent channel but cannot detect error and retransmit the data. In order to improve the reliability of serial communication, a new communication protocol is proposed. Key words boiler tubes - mobile robotics - wireless local area network Project Supported by the National High-Tech Program (Grant No. 2002AA420080)

Security Analysis of Application Layer Protocols on Wireless Local Area Networks

This paper aims at analyzing the security issues that lie in the application layer (AL) protocols when users connect to the Internet via a wireless local area network (WLAN) through an access point. When adversaries launch deauthentication flood attacks cutting users' connection, the connection managers will automatically research the last access point's extended service set identifier (ESSID) and then re-establish connection. However, such re-connection can lead the users to a fake access point with the same ESSID set by attackers. As the attackers hide behind users' access points, they can pass AL's authentication and security schemes, e.g. secure socket layer (SSL). We have proved that they can even spy on users' account details, passwords, data and privacy.

Optical local area network emulations over Ethernet passive optical networks:A survey

As a promising solution to efficiently achieving fiber to the home （FTTH）, Ethernet passive optical network （EPON） is currently improved to provide intercommunication among customers, together with normal traffic delivery, via optical local area network emulation. It is a new research direction and expected to enhance the normal EPON performances. The purpose of this article is to review the state-of -the-art solutions to emulating optical local area networks （OLANs） over EPON. We discuss the major problems involved, e.g., network architecture, control mechanisms, and other potential enhancements. We also outline areas for future researches.

Resource Exhaustion Attack Detection Scheme for WLAN Using Artificial Neural Network

IEEE 802.11 Wi-Fi networks are prone to many denial of service(DoS)attacks due to vulnerabilities at the media access control(MAC)layer of the 802.11 protocol.Due to the data transmission nature of the wireless local area network(WLAN)through radio waves,its communication is exposed to the possibility of being attacked by illegitimate users.Moreover,the security design of the wireless structure is vulnerable to versatile attacks.For example,the attacker can imitate genuine features,rendering classificationbased methods inaccurate in differentiating between real and false messages.Althoughmany security standards have been proposed over the last decades to overcome many wireless network attacks,effectively detecting such attacks is crucial in today’s real-world applications.This paper presents a novel resource exhaustion attack detection scheme(READS)to detect resource exhaustion attacks effectively.The proposed scheme can differentiate between the genuine and fake management frames in the early stages of the attack such that access points can effectively mitigate the consequences of the attack.The scheme is built through learning from clustered samples using artificial neural networks to identify the genuine and rogue resource exhaustion management frames effectively and efficiently in theWLAN.The proposed scheme consists of four modules whichmake it capable to alleviates the attack impact more effectively than the related work.The experimental results show the effectiveness of the proposed technique by gaining an 89.11%improvement compared to the existing works in terms of detection.

IAP General Circulation Models: A First Step Towards Developing a Local Area Model for Weather Prediction in Nigeria

In an earlier study, the Atmospheric Models Intercomparison Program (AMIP) simulations of African climate using the nine-layer gridpoint atmospheric general circulation model were found to be closely related to the observed European Centre for Medium Range Weather Forecast (ECMWF) temperature data at 500 and 850 hPa. This paper presents the analysis of the simulation of African climate using the Global Ocean-Atmosphere-Land System Model (IAP/LASG GOALS) and the nine-layer spectral general circulation model rhomboidally truncated at zonal wave number 15 (L9R15) developed at the Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences, Beijing. Both model simulations were not significantly different from the National Center for Environmental Prediction (NCEP) Reanalysis monthly mean data for 1980-1995 in the case of surface air temperature, sea level pressure and precipitation, with the GOALS reproducing the seasonal mean climate over Africa better. The implications of the encouraging results in developing a local area model for Nigeria have been discussed. The great role of topography in the developing of general circulation models for numerical modelling of weather and climate has been stressed.

Socio-Economic Implication of Nigeria Liquefied Natural Gas (NLNG) Project in Bonny Local Government Area, Rivers State, Nigeria

Notably, the Nigeria Liquefied Natural Gas (NLNG) project is the pioneer Liquefied Natural Gas (LNG) plant in Nigeria, aimed at both the diversification of the petroleum industry and utilization of the vastly flared natural gas resources of the nation. However, large scale energy projects have been known to generate both positive and/or negative impacts. Environmental Management Plans (EMP) have often been the compendium of information on approved mitigations, which normally include activities that could maximize the benefits of the host communities, and it’s not unusual for the Community Development and Corporate Social Responsibility (CDCSR) department of such an organization to be saddled with these contributions. But the activities of Nigeria LNG Ltd.’s CSR department have often been the source of criticism, as well as aspiration for improvement by host communities and other stake holders. This article thus aims to present a comprehensive compendium of NLNG’s CDCSR activities, up to the year 2010, and also highlight the level of satisfaction of the immediate and distant host communities against the level of performance of other donors in the area. Also the arrays of negative socio-economic consequences of the Nigeria LNG Ltd.’s activities were identified based on community perception. The results generally showed that comparatively, NLNG project has made more innovative positive socio-economic and health contributions to its areas of operation than the three tiers of government and other donors (including SPDC and Mobil Producing Nigeria). Surprisingly, agitations against Nigeria LNG Ltd.’s activities have not overshadowed its community development provisions, which have been of major assistance in several communities. There is however a dire need to review several aspects of Nigeria LNG Ltd.’s CDCSR activities, especially in the fulfilment of documented promises, as well as in project conception and community participation, for better completed projects acceptance by indigenous host communities. Conflict management strategies also need to be improved, while the dissatisfaction over benefits in New Finima needs to be urgently addressed.

在局域网上用NetMeeting进行协同设计

进行了在局域网上用NetMeeting进行协同设计的研究，说明了用NetMeeting进行协同设计的系统配置，详细论述了这种工作模式的实时特性，建立了NetMeeting协同工作体系。

Radio map updated method based on subscriber locations in indoor WLAN localization

With the rapid development of wireless local area network （WLAN） technology, an important target of indoor positioning systems is to improve the positioning accuracy while reducing the online calibration effort to overcome signal time-varying. A novel fingerprint positioning algorithm, known as the adaptive radio map with updated method based on hidden Markov model （HMM）, is proposed. It is shown that by using a collection of user traces that can be cheaply obtained, the proposed algorithm can take advantage of these data to update the labeled calibration data to further improve the position estimation accuracy. This algorithm is a combination of machine learning, information gain theory and fingerprinting. By collecting data and testing the algorithm in a realistic indoor WLAN environment, the experiment results indicate that, compared with the widely used K nearest neighbor algorithm, the proposed algorithm can improve the positioning accuracy while greatly reduce the calibration effort.

A Semi-Supervised WLAN Indoor Localization Method Based on l1-Graph Algorithm

For indoor location estimation based on received signal strength( RSS) in wireless local area networks( WLAN),in order to reduce the influence of noise on the positioning accuracy,a large number of RSS should be collected in offline phase. Therefore,collecting training data with positioning information is time consuming which becomes the bottleneck of WLAN indoor localization. In this paper,the traditional semisupervised learning method based on k-NN and ε-NN graph for reducing collection workload of offline phase are analyzed,and the result shows that the k-NN or ε-NN graph are sensitive to data noise,which limit the performance of semi-supervised learning WLAN indoor localization system. Aiming at the above problem,it proposes a l1-graph-algorithm-based semi-supervised learning( LG-SSL) indoor localization method in which the graph is built by l1-norm algorithm. In our system,it firstly labels the unlabeled data using LG-SSL and labeled data to build the Radio Map in offline training phase,and then uses LG-SSL to estimate user's location in online phase. Extensive experimental results show that,benefit from the robustness to noise and sparsity ofl1-graph,LG-SSL exhibits superior performance by effectively reducing the collection workload in offline phase and improving localization accuracy in online phase.

基于DBN的局域网非授权用户入侵检测系统

为解决非授权用户接入局域网主机的问题,降低攻击性信息对局域网安全性造成的影响,设计了基于深度置信网络(Deep Belief Nets,DBN)的局域网非授权用户入侵检测系统。在局域网架构体系中,规划用户授权模块、行为检测模块之间的分配与负载关系,完成系统的功能模块设计。借助DBN信息处理模型,匹配脚本信息与用户对象,实现对局域网入侵信息的处理。联合相关模块元件,完成局域网非授权用户入侵检测系统设计。实验结果表明,设计系统应用后,局域网主机对非授权用户入侵信息样本检测误差为0.1×10^(13)bit,保证了局域网的安全性。

基于Intranet的新城金矿管理信息系统研究与开发

根据新城金矿的技术状况,采用多种开发方式相结合的策略开发了基于Intranet的管理信息系统。介绍了局域网的建设方案,并以部分子系统为例,介绍了系统的功能和特点及开发的经验。本系统运行取得良好效果,对于数字矿区的建设具有积极的意义。

Multiusers Parallel Competitive Channel Protocol Based on Unsaturated Service

In order to enhance the area throughput of next generation wireless local area network(WLAN)in high density scenarios,orthogonal frequency division multiple access(OFDMA)has been adopted as one of the key technologies in the next generation WLAN communication standards.However,the performance of the existing media access control(MAC)degrades significantly under unsaturated services.Therefore,this paper proposes a multi-user parallel contention channel MAC(MU-MAC)based on unsaturated services,which can effectively reduce the channel access conflict and improve the OFDMA access efficiency of cluster member nodes.On this basis,MU-MAC is enhanced for the spatial clustering group(SCG)formation protocol and support for the unsaturated service characteristics.Further,the optimal access radius when the service is in a non-saturated state is analyzed to make the relevant theoretical analysis more generally,and the expressions for the throughput and area throughput of the proposed protocol are modeled and derived.The simulation results verify the correctness of the theoretical analysis and the efficiency of the protocol performance.The results show that MU-MAC outperforms IEEE 802.11ax and OMAX protocol in area throughput by 40.72%and 104.15%,respectively.

Simulation model based on Monte Carlo method for traffic assignment in local area road network

For a local area road network,the available traffic data of traveling are the flow volumes in the key intersections,not the complete OD matrix.Considering the circumstance characteristic and the data availability of a local area road network,a new model for traffic assignment based on Monte Carlo simulation of intersection turning movement is provided in this paper.For good stability in temporal sequence,turning ratio is adopted as the important parameter of this model.The formulation for local area road network assignment problems is proposed on the assumption of random turning behavior.The traffic assignment model based on the Monte Carlo method has been used in traffic analysis for an actual urban road network.The results comparing surveying traffic flow data and determining flow data by the previous model verify the applicability and validity of the proposed methodology.

基于LAN的转台机动控制虚拟动态测试分析系统设计

针对卫星姿态机动控制地面物理仿真监测实验,设计了卫星姿态机动控制性能动态测试分析系统;测试系统采用码盘作为测角传感器、数字I/O接口卡、测试目标为飞行器仿真气浮单轴实验转台,Labview和Access为开发软件;运用了动态测试技术、Lab-view与SQL连接的ADO技术,设计了库结构,利用Datasocket技术实现了实验数据的网络通讯,并介绍了系统硬件设计方法和软件系统设计方法,该系统实现了角度动态数据采集、数据自动存储、数据自动分析、数据管理及数据自动打印等实验功能,分析结果包括机动范围、姿控精度、控制误差及机动响应时间等数据项,还实现了局域网内PC机在线实验观测和实验数据备份功能;经实验验证,达到预期的实验测试任务要求。

VHT WLANs多用户MIMO传输时OBSS干扰问题的解决方案研究

交叠的基本业务集(OBSS,Overlap Basic Service Set)是无线局域网的主要场景,如何有效地满足OBSS站点的QoS要求成为无线局域网的研究重点之一。而被称为新一代Wi-Fi的VHT(Very High Throughput)WLANs多用户MIMO的引入,使得OBSS场景的干扰问题成为亟待解决的对象。本文在VHT WLANs的草案基础上,针对无线局域网OBSS(Overlap Basic Service Set)站点在新型的多用户MIMO(MU-MIMO)传输机制下的干扰问题提出了三种解决方案。第一种是基于站点信道相关性的分组方法,通过分组使各站点信道之间相互正交或近似正交来达到缓解OBSS站点的强干扰问题,从仿真结果可以看到所提方案BER性能上的优越性;第二种方案是针对需满足QoS要求的OBSS站点,在现有协议基础上提出了一种基于波束方向约束的干扰避免方案,使系统"和速率"有较大的提升,所提方案不仅能够基本解决OBSS站点的强干扰问题,而且只需较小的帧结构修改,容易实现;第三种方案则是利用干扰对齐技术,在假定站点可以同时关联多个AP的场景下,对比了采用干扰对齐方案和传统方案时对OBSS站点性能的影响。论文最后通过仿真验证了三种干扰解决方案的正确性和有效性,为新一代Wi-Fi的应用奠定了坚实的基础。

一种应用于无线局域网802.11a/n的高功率线性功率放大器设计

提出一种应用于无线局域网802.11a/n的高功率高线性度InGaP/GaAs异质结晶体管功率放大器。通过采用新颖的线性偏置电路和带宽拓展电路,该功放实现了在64正交振幅调制正交频分复用信号输入激励下,误差向量幅度(EVM)在3%时实现超过21dBm的线性输出功率,在超过1GHz频段内实现超过31dB的小信号增益。

Research and Development of Indoor Positioning

Indoor positioning systems have been sufficiently researched to provide location information of persons and devices.This paper is focused on the current research and further development of indoor positioning.The standard evolution and industry development are summarized.There are various positioning systems according to the scenarios,cost and accuracy.However,there is a basic positioning system framework including information extraction,measurement and calculation.In particular,the detailed positioning technologies mainly including cellular positioning and Local Area Network(LAN) positioning are listed and compared to provide a reference for practical applications.Finally,we summarize the challenges of indoor positioning and give a3-phase evolution route.

OFDM无线LAN系统限幅峰平比降低技术

为了减小OFDM(OrthogonalFrequencyDivisionMultiplexing)无线LAN(LocalAreaNet)系统信号的峰平比,利用信号限幅滤波技术,提出了一种适用于无线LAN系统的峰平比降低调制器实现方案,给出了其实现算法及限幅因子的调节策略;并利用计算机仿真对该系统的峰平比、功率谱和误码率性能进行了分析,仿真结果表明,限幅滤波技术可以有效地改善无线LAN系统OFDM信号的高峰平比特性。

基于局域网的某型防空导弹实时飞行动态监控系统

该文介绍了一个结合仿真和计算机网络技术 ,构造的“基于局域网 (LAN)的某型防空导弹实时飞行动态监控系统” ,详细说明了它的功能结构、硬件组成和主要的技术特点 。

学校Windows NT教学局域网的安全措施

学校教学网络大多是采用服务器 +有盘工作站架构 ,局域网络的安全对保障基于计算机的教学十分重要。本文介绍了保护WindowsNT局域网网络安全的一些管理措施 ,通过我系局域网运行情况来看 ,较好的保证了网络的安全 。