Cisco网真系统优化设计

国外开会模式与国内开会模式不同,国外是以讨论形式为主,不需要会场具备画面轮巡功能。国内网真会场实现轮巡功能是依托思科产品的动态多分屏功能,其实质是以画中画模式实现图像轮巡功能,此方法不被参会人员所采纳,因此根据需要对网真系统进行优化设计。限制于思科采取技术保护措施,不能以最简单的方案实现多会场整屏轮巡功能,需借助第三方硬件平台以及软件开发实现此功能。同时,网真软件自身没有把多路会场画面、声音、操作控制混合集成到一起,因此根据山西电力网真的需求研发出网真会议智能控制系统。优化升级后的网真系统已恢复投运,效果反映良好。

山西电力网真会议系统的应用分析

网真系统是一种通过结合超高清晰度视频、音频和交互式组件,在IP网络上创建一种独特的"面对面"体验的新型技术。它的主要目标是缩短人与人之间、人与地点之间的距离,从时间和空间感上都超越了传统会议。对该系统在山西电力的应用情况进行了分析。

网真系统对会议室照明和声学的要求

会议室环境的优化设计有助于为用户营造最佳网真体验。本文通过在会议室设计方面所给出的指导和建议，帮助用户提高网真会议体验的整体质量。在设计网真会议环境时，需要使用最先进的材料，并综合考虑会议室面积、技术环境、合适的照明和声学条件及会议桌椅的设计等众多因素。

多院区网真视频网络的QoS设计

介绍网真技术的特点,医院网真系统的设计架构和QoS的相关技术,讨论了在多院区环境下如何设计园区网络QoS,给出了配置参考方案,保障网真视频系统端到端的IP网络服务质量,充分发挥网真系统的先进性。

Question classification in question answering based on real-world web data sets

To improve question answering （QA） performance based on real-world web data sets,a new set of question classes and a general answer re-ranking model are defined.With pre-defined dictionary and grammatical analysis,the question classifier draws both semantic and grammatical information into information retrieval and machine learning methods in the form of various training features,including the question word,the main verb of the question,the dependency structure,the position of the main auxiliary verb,the main noun of the question,the top hypernym of the main noun,etc.Then the QA query results are re-ranked by question class information.Experiments show that the questions in real-world web data sets can be accurately classified by the classifier,and the QA results after re-ranking can be obviously improved.It is proved that with both semantic and grammatical information,applications such as QA, built upon real-world web data sets, can be improved,thus showing better performance.

ICN Based Vehicle-to-Cloud Delivery for Multimedia Streaming in Urban Vehicular Networks

Mobile multimedia streaming is an open topic in vehicular environment. Due to the high intermittent links, it has become a critical challenge to deliver high quality video streaming in vehicular networks. In this paper, we reform the Information Centric Networking （ICN） concept for multimedia delivery in urban vehicular networks. By leveraging the 1CN perspective, we highlight that vehicular peers can obtain multimedia chunks via the vehicle-to-cloud （V2C） approach to improve the delivery quality. Based on this, we propose a lightweight multipath selection strategy to guide the network system to adaptively adjust the forwarding means. Extensive simulations show that the proposed solution can optimize the utilization of network paths, lighten network loads as well as avoid wasting resources.

3D Simulation of Flow with Free Surface Based on Adaptive Octree Mesh System

The technique of adaptive tree mesh is an effective way to reduce computational cost through automatic adjustment of cell size according to necessity. In the present study, the 2D numerical N-S solver based on the adaptive quadtree mesh system was extended to a 3D one, in which a spatially adaptive oetree mesh system and multiple particle level set method were adopted for the convenience to deal with the air-water-structure multiple-medium coexisting domain. The stretching process of a dumbbell was simulated and the results indicate that the meshes are well adaptable to the free surface. The collapsing process of water column impinging a circle cylinder was simulated and from the results, it can be seen that the processes of fluid splitting and merging are properly simulated. The interaction of second-order Stokes waves with a square cylinder was simulated and the obtained drag force is consistent with the result by the Morison＇s wave force formula with the coefficient values of the stable drag component and the inertial force component bein~ set as 2.54.

Simulation-based Manufacturing System Modeling

In recent years, computer simulation appears to be very advantageous technique for researching the resource-constrained manufacturing system. This paper presents an object-oriented simulation modeling method, which combines the merits of traditional methods such as IDEF0 and Petri Net. In this paper, a four-layer-one-angel hierarchical modeling framework based on OOP is defined. And the modeling description of these layers is expounded, such as: hybrid production control modeling and human resource dispatch modeling. To validate the modeling method, a case study of an auto-product line in a motor manufacturing company has been carried out.

Impact of Wind Integration on Transient Voltage Stability in Regional Grid

With the increasing development of wind power,the scale of wind farms and unit capacity of wind turbines are getting larger and larger,and the impact of wind integration on power systems cannot be ignored.However,in most cases,the areas with a plenty of wind resources do not have strong grid structures.Furthermore,the characteristics of wind power dictate that wind turbines need to absorb reactive power during operation.Because of the strong correlation between voltage stability and systems' reactive power,the impacts of wind integration on voltage stability has become an important issue.Based on the power system simulation software DIgSILENT and combined analysis of actual practice,this paper investigates the impacts of two types of wind farms on voltage stability:namely a type of wind farms which are constituted by constant speed wind turbines based on common induction generators(IG) and another type of wind farms which are constituted by VSCF wind turbines based on doubly-fed induction generators(DFIG).Through investigation the critical fault clearing time is presented for different outputs of wind farms.Moreover,the impacts of static var compensator(SVC) and static synchronous compensator(STATCOM) on transient voltage stability in IG-based wind farms are studied to improve the security and stability of the Jiangsu power grid after the integration of large scale wind power.

Simulation of natural gas transmission pipeline network system performance

Simulation has proven to be an effective tool for analyzing pipeline network systems （PNS） in order to determine the design and operational variables which are essential for evaluating the performance of the system. This paper discusses the use of simulation for performance analysis of transmission PNS. A simulation model was developed for determining flow and pressure variables for different configuration of PNS. The mathematical formulation for the simulation model was derived based on the principles of energy conservation, mass balance, and compressor characteristics. For the determination of the pressure and flow variables, solution procedure was developed based on iterative Newton Raphson scheme and implemented using visual C＋＋6. Evaluations of the simulation model with the existing pipeline network system showed that the model enabled to determine the operational variables with less than ten iterations. The performances of the compressor working in the pipeline network system xvhich includes energy consumption, compression ratio and discharge pressure were evaluated to meet pressure requirements ranging from 4000-5000 kPa at various speed. Results of the analyses from the simulation indicated that the model could be used for performance analysis to assist decisions regarding the design and optimal operations of transmission PNS.

Channel Transmission Behavioral Modeling Dedicated to WSNs

The design, manufacture and deployment of embedded systems become increasingly complex and multidisciplinary process. Before the steps of manufacturing and deployment, a simulation and validation phase is necessary. Given the increasing complexity of systems such as telecommunications systems, control systems and others, a specific simulation and validation process must take place. This simulation ideally made in a single development environment should cover different areas and all components of the system. In this paper, the authors briefly describe the behavioral models of the elements of a large scale WSN （wireless sensors network） used to create simulator, focusing specifically on the model of the transmission channel, and how it can retrieve results from the behavioral simulator. In side to legacy network simulator, for the testing and modeling of communication protocols, this simulator should not omit WSN specific aspect, in accuracy it covers the modeling of node platforms, protocols, and real world phenomena.

A Simulation Environment for Intrusion Detection System in IEC 61850 Based Substation Automation System

Greater complexity and interconnectivity across systems embracing electrical power technologies has meant that cyber-security issues have attracted significant attention. In this paper a simulation environment for intrusion detection system in IEC 61850 standard-based substation automation system is provided to test simulated attacks on IEDs （intelligent electronic devices）. Intrusion detection is the process of detecting malicious attacker, so it is an effective and mature security mechanism to protect electrical facility. However, it is not harnessed when securing IEC 61850 automated substation. To prove the detection capability of the system testing environment was developed to analyze and test attacks simulated with different test cases. It shows that the simulation environment works accordingly to various network traffic scenarios and eventually proves the functionality of intrusion detection system to be later deployed in the real IEC 61850 based substation automation system site.

Embedded FPGA Simulator for Wireless Sensor Network Design

The design, manufacture and deployment of embedded systems become increasingly complex and multidisciplinary process. Before the steps of manufacturing and deployment, a simulation and validation phase is necessary. In this paper, a WSN （wireless sensors network） emulator, implemented on a FPGA, is described by： describing some models as examples, how multiple simulations can be done when the device was configured and programmed once, and how results from the behavioral emulator can be extracted. The diversity of applications and the typically scarce node resources set very tight constraints to WSN. It is not possible to fulfill all requirements with a general purpose WSN, for which reason the rapid development of application specific WSNs is preferred. A new emulator for the design, simulation, and evaluation of WSNs, implemented on a very dense FPGA （field programmable gate arrays）, is presented, exploring the parallelism and his resources to do a very rapid simulation ofa WSN for long periods, and without overloading memory by the intermediate data.

2008年多媒体会议室技术盘点

本文首先概括性的介绍了多媒体会议室系统，然后从多媒体会议室的各项最新最热的技术出发，详细介绍了各种技术的应用情况以及现状，并深入阐述了各自的技术特点，并依据实际案例分析了其市场前景。最后，展望了多媒体会议室的发展趋势。

C60-based clustering scheme for sensor management in STSS

Clustering-based sensor-management schemes have been widely used for various wireless sensor networks(WSNs), as they are well suited to the distributive and collaborative nature of WSN. In this paper, a C60-based clustering algorithm is proposed for the specific planned network of space tracking and surveillance system(STSS), where all the sensors are partitioned into 12 clusters according to the C60(or football surface) architecture, and then a hierarchical sensor-management scheme is well designed.Finally, the algorithm is applied to a typical STSS constellation,and the simulation results show that the proposed method has better target-tracking performance than the nonclustering scheduling method.