选择适当技术保证网络安全过渡

由于IPv6技术具有诸多优点，人们希望在不久的将来使用它来进行网络主要部分的设计。然而，由于IPv4网络如此庞大，以至于人们不得不需要一段时间逐步从IPv4向IPv6过渡。为此，人们正在通过各种各样的方法寻找从IPv4向IPv6过渡的合理方案，而且到目前为止已经出现了许多的解决方案。这些解决方案大致可以分成三类：一是双栈机制，二是翻译机制，三是联道机制。有些技术只使用了其中一种机制，有些则同时使用了其中两种机制。     

IPv4/IPv6过渡的安全评估

近年来,由于Internet技术的迅猛发展,使得现在广泛使用的32位IP地址面临被用完的威胁,为此IETF 提出了下一代因特网协议(IPng)即IPv6,用来取代IPv4。本文介绍了IPv4/IPv6过渡技术的机制及过程,对各种IPV4/IPV6过渡技术的安全问题进行讨论,探讨了这些过渡机制安全方面的优劣、使用中的限制、应用方式及效果。     

40ver6：基于非显式隧道的IPv4跨越IPv6互联机制

IPv6骨干网正在逐步建成并走向实用，纯IPv6的骨干网（如中国下一代互联网：CNGI）已经出现，而已有的大量互联网应用和服务仍存在于IPv4网络中，因此出现了大规模复杂IPv4网络通过IPv6骨干网互联的需求，然而目前没有满足这种需求的过渡机制．本文提出了一种基于IPv6的IPv4网络互联过渡机制框架，对40ver6过渡机制框架进行了阐述和分析，并通过原型系统实现，对40ver6机制框架进行了原理和功能验证测试．为减小路由开销，提出了ISP独立部署方案，增强了40ver6机制框架的可实施性．40ver6过渡机制框架具备对网络和端系统透明性、轻型和可自适应动态选路特性，网络管理维护负担小，可适应于大规模、复杂的网络互联等优点．     

基于MPLS VPN的IPv6过渡机制

在相当长的一段时期内，IPv4还会继续存在，这有如下几方面的原因：首先，需要保护已有的巨大投资。其次，当今世界不同的国家和地区信息基础设施的发展极端不均衡，这些差别使得在建设基于IPv6的新一代信息基础设施时，各个国家和地区的起跑线不一样，其推进策略和紧迫程度也不一样。这就决定了IPv6和IPv4这两种技术标准体制将在相当长的一段时间内同时存在，因而研究IPv6与IPv4之间的共存和平滑过渡机制具有重要的意义。IPv6的过渡机制传统的IPv6过渡机制主要有三种类型：双栈类双栈机制的定义很简单，就是在设备中同时装备IPv4与…     

下一代网络协议介绍

介绍了新一代的网络协议IPv6的技术背景和特点，以及IPv4到IPv6方案过渡要求。对IPv6引入的IP层安全体系结构(IPSec)，认证机制，加密机制等进行了研究。     

IPv4/IPv6协议过渡机制的实验研究

从IPv4向IPv6的过渡是网络发展的一大趋势，但存在很多技术问题亟待解决。为了使这一过渡尽可能地平滑，人们提出了很多解决方法。本文研究了几种主流的过渡机制，并就一个基于隧道代理的过渡方案给出其具体实现方法，并进行了实验。实验证明，该方案有效地实现了对现有IPv4网络向IPv6的升级，并保证了IPv6网络与IPv4网络的互联互通。     

从IPv4向IPv6的过渡

IETF提出的从IPv4向IPv6平稳过渡的多种机制分属双栈、翻译器和隧道等三个类型。在分别介绍了三类过渡机制之后，还讨论了影响过渡的其他因素，包括用户对IPv6的需求、网络升级的成本、新型设备的提供能力以及面临的技术问题。     

新一代的网络安全协议--IPv6

介绍了新一代的因特网网际协议——IPv6的技术背景和特点，以及IPv4到IPv6的过渡，对IPv6引入IP层的安全体系结构(IPSec)、认证机制、加密机制等进行了讨论。     

结合DNS-ALG的NAT-PT技术研究与实现

在IPv4网络向IPv6网络过渡过程中,已经出现了多种过渡技术和方案,网络地址转换-协议转换NAT-PT是IPv4/IPv6过渡过程中的一种关键技术。为了达到两种网络的无缝连接的目的,通过对NAT-PT过渡原理的分析以及对域名服务-应用层网关DNS-ALG工作机制的研究,采用了结合DNS-ALG的动态NAT-PT过渡方案,借助Cisco模拟器GNS3模拟实现了IPv6网络通过域名与IPv4网络的互通,并对该技术的工作机制进行了分析和对实验结果进行了抓包分析和验证。     

IPv4网与IPv6网互连的地址转换技术

NAT—PT过渡机制解决IPv4主机和IPv6主机互访的问题，是IPv6过渡技术中的一种。介绍NAT—PT的主要功能和工作机制。     

多路径环境下电信流量模型研究

在下一代通信网络中,一个终端可同时拥有多个网络接口,在一对源、目的终端间存在多条可用路径。这为网络通信提供了一种全新的思路,即利用多条路径并发进行数据传输。针对多路径传输出现的问题,文章为多路径传输建立了流量模型,分析了多路径传输流媒体的优势,提出了＂流体带宽＂和＂流体调度＂的概念,并引入网络流理论计算了多路径环境下的目标流量。     

Integrated Sliding‐Mode Sensorless Driver with Pre‐driver and Current Sensing Circuit for Accurate Speed Control of PMSM

This paper proposes a fully sensorless driver for a permanent magnet synchronous motor (PMSM) integrated with a digital motor controller and an analog pre‐driver, including sensing circuits and estimators. In the motor controller, a position estimator estimates the back electromotive force and rotor position using a sliding‐mode observer. In the pre‐driver, drivers for the power devices are designed with a level shifter and isolation technique. In addition, a current sensing circuit measures a three‐phase current. All of these circuits are integrated in a single chip such that the driver achieves control of the speed with high accuracy. Using an IC fabricated using a 0.18 μm BCDMOS process, the performance was verified experimentally. The driver showed stable operation in spite of the variation in speed and load, a similar efficiency near 1% compared to a commercial driver, a low speed error of about 0.1%, and therefore good performance for the PMSM drive.     

Virtual impedance control for a regional dynamic voltage restorer

A dynamic voltage restorer (DVR) can be installed in a middle-voltage (MV) power grid, to concurrently protect a cluster of sensitive loads from voltage sags. To further improve its efficiency and reduce the difficulty in its implementation, a novel control strategy for operating such a DVR as a virtual impedance in series with sensitive loads is proposed in this paper. In addition to its usual function of compensating for voltage sags, such a DVR can also operate as a virtual inductance, to function as a fault current limiter (FCL) during a downstream fault, or a virtual capacitance, to function as a series compensator (SC) to compensate the voltage loss along the feeder line during heavy load. Based on a dual-loop control design, strategies for operating a DVR as a series virtual inductance and a virtual capacitance are proposed, and methods for tuning the parameter values and a stability analysis of the whole system are presented. The feasibility and effectiveness of the proposed method are verified by simulations using the PSCAD software, and experimental results obtained using a prototype DVR are presented.     

X波段GaN HEMT内匹配器件

自主研制的GaN HEMT,栅源泄漏电流从1E-4A量级减小到了1E-6A量级,有效提高了栅漏击穿电压,改善了器件工作特性. 采用MIS结构制作了2.5mm栅宽GaN HEMT,测试频率为8GHz,漏源电压为33V时,器件连续波输出功率为18.2W,功率增益为7.6dB,峰值功率附加效率为43.0%. 2.5mm×4 GaN HEMT内匹配器件,测试频率8GHz,连续波输出功率64.5W,功率增益7.2dB,功率附加效率39%.     

Identification of the source of an interferer by comparison with known carriers using a single satellite

We describe a method for identifying the source of a satellite interferer using a single satellite. The technique relies on the fact that the strength of a carrier signal measured at the downlink station varies with time due to a number of factors, and we use a quantum‐inspired algorithm to compute a “signature” for a signal, which captures part of the pattern of variation that is a characteristic of the uplink antenna. We define a distance measure to numerically quantify the degree of similarity between two signatures, and by computing the distances between the signature for an interfering carrier and the signatures of the known carriers being relayed by the same satellite at the same time, we can identify the antenna that the interferer originated from, if a known carrier is being relayed from it. As a proof of concept, we evaluate the performance of the technique using a simple statistical model applied to measured carrier data.     

It measures like me: An IoTs algorithm in WSNs based on heuristics behavior and clustering methods

Our work stems from the consideration that nodes of a wireless sensor network, deployed on a general topology, should follow a bio-inspired approach to respect the trustability, information load, risk and energy-saving requirements, under bounded conditions of time, knowledge and computational power. It allows to introduce a multi-agent model related to Internet of Things and heuristics models, in order to obtain a smart organized network with nodes that have both social and human cognition. Our model is based on a hierarchical clustering method and an aggregation/rejection mechanism, that follows sociological and heuristics theories. The model follows the principle of sense of community and the logic of tie for similarity. The main target is to integrate the inherent cooperation of a multi-agent system with node intelligence of Internet of Things and also with the “Satisficing” of heuristic decisions in order to get a social smart behavior of the whole network.     

One-to-All Broadcasting in Petersen-Torus Networks for SLA and MLA Models

In a network, broadcasting is the dissemination of a message from a source node holding a message to all the remaining nodes through a call. This letter proposes a one-to-all broadcasting algorithm in the Petersentorus network PT(n, n) for the single-link-available and multiple-link-available models. A PT(n, n) is a regular network whose degree is 4 and number of nodes is 10n², where the Petersen graph is set as a basic module, and the basic module is connected in the form of a torus. A broadcasting algorithm is developed using a divide-and-conquer technique, and the time complexity of the proposed algorithm approximates n+4, the diameter of PT(n, n), which is the lower bound of the time complexity of broadcasting.     

A PTD‐based transaction protocol for public transportation

Advances in wireless network technology and the increasing number of users of the personal trusted device (PTD) make the PTD an ideal channel for offering personalized services to mobile users. In this paper, we propose using a PTD as a payment tool in a mobile transaction system for public transportation. To overcome the inherent weakness of computing resources in a PTD, we use a trusted observer to coordinate the mobile transaction and to integrate cryptology (such as a digital signature and a one‐way hash function). The proposed scheme satisfies the requirements for mobile transactions. These requirements include fairness, non‐repudiation, anonymity, off‐line capability, no forgery, efficient verification, simplicity, and practicability. Because a PTD is more portable and personal than a personal computer and because the public transportation can be a necessity in our daily lives, our scheme proposes a novel use of PTDs in mobile commerce. Copyright © 2008 John Wiley & Sons, Ltd.     

“信息论”课程教学方法改革的研究

"信息论"课程具有理论性强、内容抽象和知识点多等特点,本科学生学习容易产生畏惧心理。本文针对性地研究了一套教学改进方案:强化一条主线,营造一个场景;以阶段性目标为牵引,激发学生主动学习兴趣;同时,将全方位教育模式融入到"信息论"教学中,以适应不同学生的需求,平衡深度与广度之间的矛盾。经教学实践,学生学习兴趣普遍提高,教学效果良好。