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1.
在一个开源的SIP协议栈oSIP的基础上,讨论了SIP可视电话的总体结构及各个组成模块、客户端的协议栈结构和基本的呼叫流程。结果表明,该可视电话实现了设计所要求的功能。 相似文献
2.
多媒体通信协议分析 总被引：1，自引：0，他引：1
朱萍 《福建信息技术教育》2006,(3)
随着VOIP和视频通信的发展,H.323和SIP作为IP多媒体通信领域中被广泛采纳的两种信令控制协议,受到业界的普遍重视。H.323和SIP这两种关键协议各具特色,它们通过互通协调,在各自的领域内必将会有更大的发展前景。 相似文献
3.
朱萍 《宁德师专学报(自然科学版)》2007,19(1):36-38
随着VoIP和视频通信的发展,H.323和SIP作为IP多媒体通信领域中被广泛采纳的两种信令控制协议,受到业界的普遍重视.对这两种关键协议分析比较,认为将二者互通协调,H.323和SIP在各自的领域内必将会有更大的发展前景. 相似文献
4.
会话初始化协议SIP是一种应用层控制协议，可方便地创建、修改和释放多媒体会话，目前已被应用于移动互联智能家居，其特点是易用、低成本。基于此，利用SIP作为网络传输协议、SPI作为串口通讯接口，采用Eclipse和Android作为开发工具，实现一套支持多媒体播放，能够与智能手机交互的梯口机系统。运行结果表明，该系统不仅能够远程获取和管理访客信息，而且可以随时随地接收社区广播及各种推送信息，有效提高社区生活的安全性、便捷性和智能化水平。 相似文献
5.
针对Android蓝牙协议栈BlueZ架构的不合理性,提出设计一种轻量化Android蓝牙协议栈.在不改变蓝牙基本协议的前提下,根据Android系统架构的特点,通过对协议栈分散代码的整合和对协议栈代码的裁剪,来达到系统更轻便、架构更合理、性能更优化的效果.最后,通过实验验证了新协议栈的可行性和有效性. 相似文献
6.
SIP协议正成为VOIP通信的主流协议之一。全面分析了SIP协议面临的安全威胁,然后提出了其加密机制和认证机制的改进方法,并部署安全SIP解决方案。 相似文献
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8.
介绍了SIP协议并列举了其面对的典型威胁,着重分析了SIP的认证机制并指出其缺陷,然后引入数字签名,提出了一种混合双向认证机制。 相似文献
9.
针对原始Android蓝牙协议栈在功能移植上的不合理性，提出其体系架构改进思路。通过实例探讨原始Android蓝牙协议栈和改进的Android蓝牙协议栈的功能移植方法，并进行对比分析。结果表明，改进的Android蓝牙协议栈在功能移植上更具有效性和合理性。 相似文献
10.
赖松青 《中国现代教育装备》2009,(10):54-56
本文根据《国家教育考试网上巡查系统技术规范标准》介绍了SIP协议在国家教育考试巡查系统中的应用。提出了SIP编码器的概念,并重点论述了SIP协议在国家教育考试巡查系统编码设备中的设计与实现。 相似文献
11.
一种基于SIP的VoIP语音通信系统的应用研究 总被引：1，自引：0，他引：1
由于SIP协议具有可扩展性、较为灵活、比较简单和易于实现等优点,将逐渐代替H.323协议,成为VoIP技术的核心协议,因而基于SIP的VoIP语音通信系统及其增值业务功能扩展的应用研究具有一定的现实意义。首先介绍了SIP和VoIP的基本概念和原理,然后设计了一个VoIP校园网络方案,最后通过实验对系统进行测试,系统测试结果表明该系统具有良好的应用前景。 相似文献
12.
王长青 《南昌教育学院学报》2010,25(6):191-191
SIP是一种与HTTP类似的基于文本的协议。通过SIP可以减少各种应用特别是高级应用的开发时间。而且固定网运营商也已经逐渐地认识到SIP对于他们的深远意义。 相似文献
13.
Lashley and Rosellini (1980) have recently suggested that schedule-induced polydipsia (SIP) is determined by the occurrence of absolute periods within schedules of periodic food delivery which are associated with a low probability of food delivery, that is, CS? periods. To assess this hypothesis, SIP was examined in the present experiments under three schedules—fixed time, variable time, and random time (RT)—which differed in probability of occurrence and/or duration (Experiment 1), and under a range of RT schedules in which the CS? period was systematically varied by changing the interpellet interval (Experiment 2). In both experiments, the level and temporal distribution of SIP did not seem to be related to the absolute period associated with the absence of food. Instead, SIP was more systematically related to the average length of the interpellet interval and, therefore, to the average period associated with no food. It was suggested that drinking under intermittent schedules of pellet delivery, that is, SIP, is determined by an average CS? period and not by an absolute period associated with the unavailability of food. 相似文献
14.
目前,企业内部大量部署的是支持SIP的IP-PBX,将计算机网和电话网集成在一起;NAT技术的出现,缓解了IP地址紧张的局面.通过NAT设备实现企业内部私网连接到公网.但NAT设备不能支持运用SIP协议的音频和视频的穿越,因此,实现SIP穿越NAT是一个迫在眉睫的难题.本方案中提出SIP Trunk网关技术,在不增加辅助设备的情况下,实现SIP协议成功的穿越NAT,节省了造价和维修成本. 相似文献
15.
Wang Guan Hao Mingyue Liu Qiong Jiang Yanlong Huang Haibin Yang Guilian Wang Chunfeng 《Journal of Zhejiang University. Science. B》2021,22(5):348-365
This study probed the protective effect of recombinant Lactobacillus plantarum against hydrogen peroxide(H_2O_2)-induced oxidative stress in human umbilical vein endothelial cells(HUVECs). We constructed a new functional L. plantarum(NC8-p SIP409-alr-angiotensin-converting enzyme inhibitory peptide(ACEIP)) with a double-gene-labeled non-resistant screen as an expression vector. A 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2 H-tetrazolium bromide(MTT) colorimetric assay was carried out to determine the cell viability of HUVEC cells following pretreatment with NC8-p SIP409-alr-ACEIP. Flow cytometry(FCM) was used to determine the apoptosis rate of HUVEC cells. Cysteinyl aspartate specific proteinase(caspase)-3/8/9 activity was also assayed and western blotting was used to determine protein expression of B-cell lymphoma 2(Bcl-2), Bcl-2-associated X protein(Bax), inducible nitric oxide synthase(i NOS), nicotinamide adenine dinucleotide phosphate oxidase 2(gp91 phox), angiotensin II(Ang II), and angiotensin-converting enzyme 2(ACE2), as well as corresponding indicators of oxidative stress, such as reactive oxygen species(ROS), mitochondrial membrane potential(MMP), malondialdehyde(MDA),and superoxide dismutase(SOD). NC8-p SIP409-alr-ACEIP attenuated H_2O_2-induced cell death, as determined by the MTT assay. NC8-p SIP409-alr-ACEIP reduced apoptosis of HUVEC cells by FCM. In addition, compared to the positive control, the oxidative stress index of the H_2O_2-induced HUVEC(Hy-HUVEC), which was pretreated by NC8-p SIP409-alr-ACEIP, i NOS,gp91 phox, MDA, and ROS, was decreased obviously; SOD expression level was increased; caspase-3 or-9 was decreased, but caspase-8 did not change; Bcl-2/Bax ratio was increased; permeability changes of mitochondria were inhibited; and loss of transmembrane potential was prevented. Expression of the hypertension-related protein(Ang II protein) in HUVEC cells protected by NC8-p SIP409-alr-ACEIP decreased and expression of ACE2 protein increased. These plantarum results suggested that NC8-p SIP409-alr-ACEIP protects against H_2O_2-induced injury in HUVEC cells. The mechanism for this effect is related to enhancement of antioxidant capacity and apoptosis. 相似文献
16.
Schedule-induced polydipsia (SIP) is a function of interpellet-interval (IPI) durations: intermediate (40-180-sec) IPIs are most effective in producing SIP, while longer and shorter IPIs are increasingly less effective. In order to determine whether each IPI exerts its influence on SIP by regulating drinking during that IPI itself or during the immediately succeeding IPI, rats were presented with systematic sequences of IPI durations during individual sessions of SIP testing. It was found that a very brief (20-sec) IPI tended to reduce the duration of drinking during the ongoing IPI, but that a very long (4-min) IPI reduced the probability that any drinking would occur during subsequent IPIs. It was suggested that the motivation to drink is reduced following long IPIs, while feeding, or behaviors anticipatory to feeding, compete with drinking when IPI lengths are very short. 相似文献
17.
本文介绍了会话初始协议（SIP协议）,分析了SIP的系统构成和工作原理,阐述了SIP在软交换和3G移动通信中的应用,对SIP的未来做出了展望。 相似文献
18.
洪亮 《邢台职业技术学院学报》2013,(5):95-98
当前,基于SIP的VoIP运用越来越广泛.本文介绍了基于SIP协议的VoIP工作原理,重点分析了基于SIP协议的VoIP所面临的安全威胁,并对可用于SIP协议的各种安全机制进行了研究. 相似文献
19.
学业不良儿童的社会信息加工是当前学业不良研究的一个重要领域。本文从学业不良儿童社会信息加工的阶段及其特点,社会信息加工与各影响因素之间关系这两个角度出发,对现有研究进行梳理,并进行了简要评价与展望。 相似文献
20.
计算机支持的协作学习（Computer Supported Collaborative Lemming,CSCL）,作为远程教育领域的一种新型的分布式学习模式,一直受到国内外研究者的关注．随着协作学习的深入开展,人们对CSCL系统的灵活性提出了更高的要求．本文将SIP协议引入到计算机支持的协作学习领壤利用其在会话方面具有的灵活、方便、易扩展的橙睦,设计并构建了一个基于SIP协议的QCL系统． 相似文献