国家电网IMS承载网网络架构设计方案及带宽测算方法

深入研究和对比分析了国家电网IMS承载网的网络架构设计方案,包括骨干侧网络架构设计方案和过渡期网络架构设计方案,并依据网络架构、媒体流和信令流走向提出了IMS交换网对数据通信网骨干侧、接入侧的带宽需求和测算方法,对国家电网建设IMS承载网具有指导意义.     

IMS对SIP协议的要求及应用

IP多媒体核心子系统(IMS)近年来日益成为比较受认同的固定网络和移动网络融合的理想方案,而会话发起协议(SIP)是IMS的基本控制协议,它自身的特点使得它在固网和移动网络向下一代网络(NGN)迈进的过程中发挥日益突出的重要作用。文章就SIP在IMS中的基本应用、扩展应用做了具体的分析,并通过IMS中SIP信令典型流程阐述了SIP在IMS中的应用。     

Thermal Effect of Ceramic Substrate on Heat Distribution in Thermoelectric Generators

In thermoelectric generators (TEG), poor system design and load matching, which make the system less efficient, have been limiting factors in achieving high conversion efficiency. In this work, to consider the effect of the inlet plenum arrangement and the laminar coolant flow temperature variation in the heat sink, a parallel microchannel heat sink is applied to a real TEG. The focus of this study is a discussion of the temperature difference variation between the cold/hot sides of the TEG legs versus the variation of the thermal conductivity of the ceramic substrate and the thickness of the substrate on the hot side. While the imposed heat flux on the TEG is homogeneously constant, different pressure drops are applied along the microchannel heat sink. The three-dimensional governing equations for the fluid flow and heat transfer are solved using the finite-volume method. The results show that the temperature difference is affected remarkably by the pressure drops in the heat sink, the thermal conductivity of the ceramic substrate, and the thickness of the substrate on the hot side.     

IMS与传统PSTN网络的互通问题研究

目前,下一代网络（NGN）的核心技术正从传统软交换向IP多媒体子系统（IMS）衍化。在IMS这个全新的网络构架下,如何实现与传统公用交换电话网（PSTN）的互通成为目前网络转化过程中急需解决的问题之一。从阐述IMS网络的系统架构入手,通过典型的呼叫实例分析,探讨从IMS终端到PSTN终端的呼叫流程。着重分析互通过程中各IMS网络功能实体的详细作用,以及会话发起协议（SIP）与综合业务数字网用户部分（ISUP）之间的转换映射关系。     

IMS域策略与计费控制接口的平滑演进

为了提供更好的基于流的计费和策略控制,3GPP在IMSR7版本中提出策略与计费控制体系架构,其基本思路是将IMSR6版本中的策略决策功能实体和计费策略功能实体合并为R7中的策略与计费规则功能实体。本文首先简要介绍了IMSR6和IMSR7控制模型;然后重点分析了与策略控制、计费控制相关Gx接口、Rx接口的接口消息及其参数。分析表明,通过定义特定AVP,实现了IMSR6向IMSR7策略控制和计费控制接口的平滑演进。     

浅谈IP多媒体子系统业务平台

文章研究了3GPP在UMTSRel5、Rel6演进版本中提出的IP多媒体子系统(IMS),描述了IMS在基于分组域上提供电话和非电话业务的系统架构。IMS的提出对固网和移动网络的融合起到了很大的推动作用,研究基于IMS的统一业务平台对下一代业务平台体系架构具有一定参考意义。     

基于VxWorks的航空发动机控制系统软件设计

在深入研究发动机控制系统软件设计要求的基础上,应用VxWorks操作系统给出了航空发动机数字电子控制器的多任务环境的设计方法、设计了数字电子控制系统的应用软件。该应用软件采用C++语言设计,根据数字电子控制系统的要求及控制目标,依照高内聚、低耦合的软件设计原则,对各种任务进行了分类并模块化开发,完成了软件设计工作。该软件满足某型航空发动机的控制功能、性能及可靠性要求。     

A new analytical model for the thermal resistance of deep-trench bipolar transistors

A new analytical model for the thermal resistance, temperature profile, and heat flow of deep-trench isolated (DTI) transistors is presented by taking the finite heat flow through the trenches into account. The new model is able to distinguish between the different contributions to the thermal resistance of the DTI structure and allows identification of the most dominant component. A detailed analysis of the substrate contribution shows that the substrate thermal resistance is overestimated in existing models. Results are compared with experimental data as well as numerical simulations and show a good agreement. The model can be used for process optimization and in a circuit simulator.     

Modeling of thermal behavior in SOI structures

Several physics-based analytical steady-state heat flow models for silicon-on-insulator (SOI) devices are presented, offering approaches at different levels of accuracy and efficiency for prediction of temperature profiles induced by power dissipated in SOI MOSFETs. The approaches are verified with the rigorous device simulation based on the energy transport model coupled with the heat flow equation. The models describe the one-dimensional temperature profile in the silicon film of SOI structure and two-dimensional heat flow in FOX, accounting for heat loss to the substrate via BOX and FOX, heat loss to (or gain from) interconnects, and heat exchanges between devices. These models are applied to investigate thermal behavior in single SOI devices and two-device SOI structures.     

一种基于SIP扩展实现IMS多域间QoS方案

以IMS为核心的NGN网络己被认为是适应未来固定网与移动网融合的网络架构。要实现IMS跨网络的QOS保证，需要域间、上下层的相互协作。丈中分析了IMS QoS机制，指出了在资源协商、资源预留以及资源保证方面SIP协议的不足，提出了一种基于SIP扩展实现多域间QoS的方案，分析了该方案所带来的在信令流程中减少信令负荷等方面的改进，并给出了具体实现方案。     

SIP Multicast-Based Mobile Quality-of-Service Support over Heterogeneous IP Multimedia Subsystems

The Universal Mobile Telecommunications System (UMTS) all-IP network supports IP multimedia services through the IP Multimedia Subsystem (IMS). This paper proposes a mobile Quality-of-Service (QoS) framework for heterogeneous IMS interworking. To reduce the handoff disruption time, this framework supports the IMS mobility based on the concept of Session Initiation Protocol (SIP) multicast. In our approach, the mobility of a User Equipment (UE) is modeled as a transition in the multicast group membership. With the concept of dynamic shifting of the multicast group's members, the flow of actual data packets can be switched to the new route as quickly as possible. To overcome mobility impact on service guarantees, UEs need to make QoS resource reservations in advance at neighboring IMS networks, where they may visit during the lifetime of the ongoing sessions. These locations become the leaves of the multicast tree in our approach. To obtain more efficient use of the scarce wireless bandwidth, our approach allows UEs to temporarily exploit the inactive bandwidths reserved by other UEs in the current IMS/access network. Analytic and simulation models are developed to investigate our resource reservation scheme. The results indicate that our scheme yields comparable performance to that of the previously proposed channel assignment schemes.     

基于IMS系统架构的移动视频解决方案

本文通过对视频监控技术和IMS技术的分析,给出了基于IMS系统架构的移动视频解决方案,并对系统中的关键流程和技术进行了论述。     

Experiments on low velocity cooling of high conductivity substrates

Experiments are reported on low velocity cooling of a heater-on-substrate geometry for high conductivity substrate materials. Four different substrate materials were studied: 1) aluminum 6061-T6; 2) aluminum nitride; 3) alumina; 4) FR-4. The effects of combined buoyancy and forced air flow, geometric orientation, substrate size, thermal conductivity, and emittance on heat transfer are evaluated. Results define the performance of the substrates and the limits of conjugate mixed convection for horizontal substrates, and of orientation effects for substrates tilted from buoyancy-opposing to buoyancy-assisting orientations. An analytical approximation is described that predicts the experimental data with good accuracy over broad parameter ranges     

基于IMS的组合类多媒体会议业务的研究和设计

本文根据目前3GPP和IETF以及OMA对IMS中会议、群组、Presence以及消息类业务的研究,提出了在IMS环境下组合类多媒体会议(融合消息、群组、电子白板和应用共享)的设计实现方案,并描述了几个具体的业务场景流程.该方案相对于现有的复杂的基于H.323的会议系统更加简单实用.     

Application-Level QoS Negotiation and Signaling for Advanced Multimedia Services in the IMS

The IP multimedia subsystem (IMS) has been recognized as a reference next-generation network architecture for offering multimedia services over an Internet Protocol (IP)-based infrastructure. One of the key benefits of the IMS is efficient and flexible introduction of new services and access to third-party application providers, thanks to standard interfaces and standardized service capabilities. To support novel media-rich applications across a wide range of user devices and access networks, IMS must support negotiable quality of service (QoS) for IP multimedia sessions. In this article, we describe the application-level QoS signaling as specified by the 3GPP and propose some enhancements based on advanced QoS parameter matching and optimization functionality to be included along the signaling path. We outline various signaling flow scenarios and discuss them in the context of a case study involving an IMS-supported 3D virtual environment, featuring a treasure-hunt-like game.     

水基料浆注凝法生产氧化铝陶瓷基片的关键技术

介绍了水基料浆注凝法工业化生产氧化铝陶瓷基片的工艺流程,分析了该工艺与传统采用的有机料浆流延法的不同和优势,着重讲述了作者在具体操作中所解决的关键技术:基片材质组分设计优化、料浆配制技术、组合模具设计制造、氧化-还原引发凝胶化、坯片无(少)变形干燥、基片尺寸精密控制、叠层烧结工艺制度、整平热处理工艺、边角料回收处理再利用.     

基于IMS的呼叫中心系统设计初探

IMS是3GPP在UMTSR5及其以后版本中定义的一个新的核心网络域,它是一个基于IP技术的、与接入无关的架构。本文结合IMS网络体系结构和呼叫中心的特点,设计了一种基于IMS的呼叫中心系统,包括总体架构、功能设计和基于SIP消息的信令流程分析,并给出该系统的特点与总结,最后对该系统的市场应用前景进行了展望。     

IP多媒体子系统(IMS)的基本框架结构

本文对IP多媒体子系统(IMS)的发展背景,系统组件和基本框架结构进行了介绍,分析了基于IMS系统的呼叫流程和业务体系。最后对IMS技术的发展前景以及其在下一代网络中的地位进行了分析。     

基于IMS网络的IPTV分析与研究

本文介绍了IMS网络的体系结构以及IPTV的发展。分析非IMS架构的传统IPTV的架构方式,传统的IPTV有其固有的局限性,引出基于IMS系统的IPTV架构并进行阐述。对IPTV的业务管理和控制管理等关键技术做了较为详细的说明。通过实验网,实现了基于IMS的IPTV。并通过实验数据详细描述了IPTV的通信流程以及流媒体控制中的SDP所携带流媒体信息,用具体数据分析IPTV在IMS网络中的通信流程和流媒体传播。     

Reducing Signaling Traffic for the Authentication and Key Agreement Procedure in an IP Multimedia Subsystem

In the IP multimedia subsystem (IMS) of UMTS, two authentication procedures are necessary for IMS subscribers before accessing IMS services: (i) packet-switch domain authentication using the authentication and key agreement of the 3rd Generation Partnership Projects (3GPP AKA), and (ii) IMS authentication using IMS AKA. However, since IMS AKA is based on 3GPP AKA, almost all of the operations are the same. Besides, IMS AKA needs two round-trips to carry out. Therefore, it is inefficient that almost all involved steps in IMS AKA are duplicated. Therefore, we propose a one-pass IMS AKA instead of IMS AKA. The one-pass IMS AKA can keep the security properties of IMS AKA, such as mutual authentication and key agreement. Furthermore, the one-pass IMS AKA not only has at least 45% improvement over IMS AKA in terms of authentication signaling, but also has 76.5% improvement over IMS AKA in terms of storage space.