3G移动通信系统移动IP关键技术探究

随着3G技术的发展,现代社会对移动通信技术的要求越来越高,用户对如何灵活有效的运用网络资源有着极大兴趣,于是移动IP技术应运而生,该技术可以帮助用户随时随地的连接无线网络,获得更加迅捷、快速的用户体验。尤其是在4G时代,移动IP技术的应用将更加普及和广泛。鉴于此,本文对G移动通信系统移动IP技术进行了探讨。     

5G移动通信关键技术及发展趋势分析

近些年来,随着我国经济的快速发展,我国的电信业进入了高速发展期。尤其是智能手机的应用使得数据通信的增长趋势迅猛,在不远的将来数据通信业务将取代语音通信成为电信运营商的新的增长点。现今移动通信网络已经建成并应用到了第四代通信网络即4G通信,为了适应增长越来越快的移动数据通信的需求,新一代的5G通信网络正在紧锣密鼓的研发中。本文将在分析5G移动通信网络特点及技术要点的基础上对5G移动通信网络未来的发展趋势进行分析阐述。     

5G新基建对未来的影响和机遇

正自1973年美国工程师马丁·库帕率先研发出移动电话以来,移动通信已有近半个世纪的历史,如今移动通信技术已经发展到第5代。5G通信,即第5代网络通信技术(5th Generation Mobile Networks),相比4G网络,5G网络具有更高的速度,更低的功耗和在生活生产领域更广泛的应用。5G无线基础设施极大改善了前几代无线通信网络基础设施性能。5G可以灵活适应不同的业务和场景,为行业信息化系统赋能。随着5G技术的不断突破和应用的不断扩展,5G通信对未来各行各业将产生深刻的影响,也为时代发展带来了无穷的机遇和挑战。     

第四代移动通信(4G)关键技术

当前,移动通信技术正以前所未有的速度飞速发展,转眼之间已经发展到了第三代。与前两代技术相比,第三代移动通信技术可以提供多种宽带信息业务。但是由于3G系统使用上代网络作为中心,因此具有智能化不足的局限性。所以,在3G商业化尚未完成之际,世界范围内的通信行业纷纷将目光聚集在下一代的移动通信技术之上。文章阐述了4G通信系统的特点,并对其关键技术进行了介绍。     

4G网络切换技术研究及其它关键技术探讨

在移动通信系统中,切换技术对于保持移动用户业务的连续性有着至关重要的作用。在4G移动通信系统业务不断的多样化的背景下,网络切换技术的优劣将对整个系统的性能有着深刻的影响。本文首先介绍了网络切换的类型,在此基础上研究两类基于4G网络切换控制方式：资源感知切换控制,多业务动态优先级切换控制。最后对4G网络的其它关键技术进行了探讨。     

浅谈第四代移动通信系统中的关键技术

随着人们对移动通信系统的各种需求与日俱增,3G系统已经开始不能满足现代移动通信系统日益增长的高速多媒体数据业务。在目前第三代移动通信系统给我们带来优质服务的同时,第四代移动通信系统的技术也在快速发展中。本文介绍T4G系统中的关键技术,如OFDM,MIMO等,这些技术的融合将使4G系统成为一个无缝连接的统一系统,从而实现跨系统的全球漫游及业务的可携带性。     

第三代移动通信--现代无线技术面向IP的应用

文章首先回顾了第一代（模拟）移动通信和第二代（数字）移动通信技术的演进,预测今后10年是移动通信大发展时期,它的用户将超过固定电话用户数。随着因特网的发展,移动通信业务将从话音扩展到数据,移动通信技术也将从电路模式发展到分组模式。文章在简介即将投入应用的第二代半移动通信技术之后,引出面向宽带多媒体应用的第三代移动通信（3GM）,重点介绍了被选作3GM国际无线传输技术标准的几种主流方案及其关键技术,特别对其中由我国提交的TD-SCDMA方案的技术特点作了说明,最后展望了网络如何从第二代移动通信过渡到第三代移动通信及3GM核心网发展趋势。     

3G移动通信系统的无线网络优化

随着电信行业的发展,第三代移动通信系统的运营牌照已经发放。出于满足业务发展和城市高话务区容量的需要,引入第三代移动通信系统势在必行,无线网络的建设、优化技术对网络质量显得尤为重要。根据3G移动通信系统的技术标准,目前用的最多的是3G系统:WCDMA系统、CDMA2000系统和TD-SCDMA系统三种,分别阐述这三种系统,并对它们之间的异同进行综合分析,进而得出网络优化的流程并展望网络优化的发展趋势。     

世博TD-LTE演示网

人们刚刚对第三代移动通信（3G）有所了解,上海世博会应用的TD-LTE规模演示网络又将一项崭新的通信技术推入公众视野。TD-HTE是我国自主研制的第三代移动通信技术TD-SCDMA的“升级版”,已经被国际电联纳入4G候选国际标准。     

4G网络的特性和安全性探讨

从美国AT＆T公司在上世纪七十年代中后期研制出的第一套蜂窝移动通信系统开始,移动通信技术在科学技术突飞猛进的背景下也实现了很大的发展。第三代移动通信系统已经进入全球范围内的实际应用阶段,第四代移动通信系统的特性与安全性随之成当前人们关注的热点问题。本文主要从4G网络的网络结构和特性出发,对4G网络的安全性进行探讨。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.