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A solution to the unit commitment problem—a review

B. SARAVANAN, Siddharth DAS, Surbhi SIKRI, D. P. KOTHARI

《能源前沿(英文)》 2013年 第7卷 第2期   页码 223-236 doi: 10.1007/s11708-013-0240-3

摘要: Unit commitment (UC) is an optimization problem used to determine the operation schedule of the generating units at every hour interval with varying loads under different constraints and environments. Many algorithms have been invented in the past five decades for optimization of the UC problem, but still researchers are working in this field to find new hybrid algorithms to make the problem more realistic. The importance of UC is increasing with the constantly varying demands. Therefore, there is an urgent need in the power sector to keep track of the latest methodologies to further optimize the working criterions of the generating units. This paper focuses on providing a clear review of the latest techniques employed in optimizing UC problems for both stochastic and deterministic loads, which has been acquired from many peer reviewed published papers. It has been divided into many sections which include various constraints based on profit, security, emission and time. It emphasizes not only on deregulated and regulated environments but also on renewable energy and distributed generating systems. In terms of contributions, the detailed analysis of all the UC algorithms has been discussed for the benefit of new researchers interested in working in this field.

关键词: unit commitment (UC)     optimization     deterministic load     stochastic load     evolutionary programming (EP)     hybrid    

Estimation of composite load model with aggregate induction motor dynamic load for an isolated hybrid

Nitin Kumar SAXENA,Ashwani Kumar SHARMA

《能源前沿(英文)》 2015年 第9卷 第4期   页码 472-485 doi: 10.1007/s11708-015-0373-7

摘要: It is well recognized that the voltage stability of a power system is affected by the load model and hence, to effectively analyze the reactive power compensation of an isolated hybrid wind-diesel based power system, the loads need to be considered along with the generators in a transient analysis. This paper gives a detailed mathematical modeling to compute the reactive power response with small voltage perturbation for composite load. The composite load is a combination of the static and dynamic load model. To develop this composite load model, the exponential load is used as a static load model and induction motors (IMs) are used as a dynamic load model. To analyze the dynamics of IM load, the fifth, third and first order model of IM are formulated and compared using differential equations solver in Matlab coding. Since the decentralized areas have many small consumers which may consist large numbers of IMs of small rating, it is not realistic to model either a single large rating unit or all small rating IMs together that are placed in the system. In place of using a single large rating IM, a group of motors are considered and then the aggregate model of IM is developed using the law of energy conservation. This aggregate model is used as a dynamic load model. For different simulation studies, especially in the area of voltage stability with reactive power compensation of an isolated hybrid power system, the transfer function of the composite load is required. The transfer function of the composite load is derived in this paper by successive derivation for the exponential model of static load and for the fifth and third order IM dynamic load model using state space model.

关键词: isolated hybrid power system (IHPS)     composite load model     static load     dynamic load     induction motor load model     aggregate load    

面向工业制造的确定性网络技术发展研究

汪硕,王佳森,蔡磊,黄韬,卢华,刘韵洁

《中国工程科学》 2021年 第23卷 第2期   页码 22-29 doi: 10.15302/J-SSCAE-2021.02.004

摘要:

面向工业制造的确定性网络技术作为兼具理论创新性与技术实用性的前沿领域,对推动新一代工业互联网技术创新、促进工业制造和高质量网络融合发展具有价值,也为抢占确定性网络技术制高点、抓住新的经济增长点提供机遇。本文从制造企业、通信厂商两方面研判了面向工业制造的确定性网络技术发展需求,详细梳理了国内外面向工业制造的确定性网络技术发展现状和趋势;进一步凝练我国面向工业制造的确定性网络技术发展面临的挑战,完成了面向工业制造的确定性网络技术发展阶段划分:试点示范阶段、规模化复制阶段、自发创新驱动阶段。研究表明,我国“确定性网络 + 工业制造”发展需要重点关注:成立产业联盟促进生态发展,加快形成公网专用的先发优势,重视行业发展路径选取,加大应用创新发展的资源保障,加强基础理论和关键技术研究,注重“产学研”一体化人才培育。

关键词: 工业制造     工业互联网     确定性网络     时间敏感网络     第五代移动通信     服务质量    

Calculation method of load distribution on pipe threaded connections under tension load

Shoujun CHEN, Lianxin GAO, Qi AN

《机械工程前沿(英文)》 2011年 第6卷 第2期   页码 241-248 doi: 10.1007/s11465-011-0219-x

摘要:

This paper presents a new calculation method that can calculate the load distribution on pipe threaded connections under tension load. On the basis of elastic mechanics, the new method was developed by analyzing each thread tooth, and a new deformation and covariant equation by making a mechanics analysis on each thread tooth was obtained. Compared with the traditional method proposed by the previous references, the new deformation and covariant equation could be used to describe the relation between the previous and the next thread tooth. By applying the new method on the sample of P-110S pipe threaded connection, the obtained results show that the load on thread tooth mainly concentrates on the four or five threads engaged and the middle teeth were not utilized well to bear the loads. The model offers a new way to calculate the loads carried on the thread teeth under tension load.

关键词: load distribution     calculation method     pipe threaded connections     tension load    

Comparison of optimal capacitor placement methods in radial distribution system with load growth andZIP load model

Veera Venkata Satya Naryana MURTY, Ashwani KUMAR

《能源前沿(英文)》 2013年 第7卷 第2期   页码 197-213 doi: 10.1007/s11708-013-0249-7

摘要: In this paper, a combined power loss sensitivity (PLS) index-based approach is proposed to determine the optimal location of the capacitors in the radial distribution system (RDS) based on the real and reactive combined loss sensitivity index, as capacitor placement not only reduces real power loss with voltage profile improvement but also reduces reactive power loss due to the reactive power compensation in the network. The results have been obtained with the existing methods of power loss index (PLI) and index vector (IV) method for comparison. Besides, the optimal placement has been obtained with the proposed method as well as existing methods and the total kVar support has been obtained. In addition, the results of net cost savings for the 10-, 34-, and 69-bus systems are obtained for comparison. Moreover, the results have been obtained for a large system of 85 buses to validate the results with combined sensitivity based approach. Furthermore, the load growth factor has been considered in the study which is essential for the planning and expansion of the existing systems, whereas the impact of the realistic load model as ZIP load model has been considered for the study of all the systems.

关键词: load growth     load models     reactive power compensation     radial distribution system     power loss index (PLI)     power loss sensitivity (PLS)     index vector (IV)    

A practical multi-lane factor model of bridges based on multi-truck presence considering lane load disparities

《结构与土木工程前沿(英文)》 2021年 第15卷 第4期   页码 877-894 doi: 10.1007/s11709-021-0756-2

摘要: Many bridge design specifications consider multi-lane factors (MLFs) a critical component of the traffic load model. Measured multi-lane traffic data generally exhibit significant lane disparities in traffic loads over multiple lanes. However, these disparities are not considered in current specifications. To address this drawback, a multi-coefficient MLF model was developed based on an improved probabilistic statistical approach that considers the presence of multiple trucks. The proposed MLF model and approach were calibrated and demonstrated through an example site. The model sensitivity analysis demonstrated the significant influence of lane disparity of truck traffic volume and truck weight distribution on the MLF. Using the proposed approach, the experimental site study yielded MLFs comparable with those directly calculated using traffic load effects. The exclusion of overloaded trucks caused the proposed approach, existing design specifications, and conventional approach of ignoring lane load disparity to generate comparable MLFs, while the MLFs based on the proposed approach were the most comprehensive. The inclusion of overloaded trucks caused the conventional approach and design specifications to overestimate the MLFs significantly. Finally, the benefits of the research results to bridge practitioners were discussed.

关键词: bridges     multi-lane factor     traffic load     lane load disparity     multi-truck presence     weigh-in-motion data    

Shape design of arch dams under load uncertainties with robust optimization

Fengjie TAN, Tom LAHMER

《结构与土木工程前沿(英文)》 2019年 第13卷 第4期   页码 852-862 doi: 10.1007/s11709-019-0522-x

摘要: Due to an increased need in hydro-electricity, water storage, and flood protection, it is assumed that a series of new dams will be build throughout the world. The focus of this paper is on the non-probabilistic-based design of new arch-type dams by applying means of robust design optimization (RDO). This type of optimization takes into account uncertainties in the loads and in the material properties of the structure. As classical procedures of probabilistic-based optimization under uncertainties, such as RDO and reliability-based design optimization (RBDO), are in general computationally expensive and rely on estimates of the system’s response variance, we will not follow a full-probabilistic approach but work with predefined confidence levels. This leads to a bi-level optimization program where the volume of the dam is optimized under the worst combination of the uncertain parameters. As a result, robust and reliable designs are obtained and the result is independent from any assumptions on stochastic properties of the random variables in the model. The optimization of an arch-type dam is realized here by a robust optimization method under load uncertainty, where hydraulic and thermal loads are considered. The load uncertainty is modeled as an ellipsoidal expression. Comparing with any traditional deterministic optimization method, which only concerns the minimum objective value and offers a solution candidate close to limit-states, the RDO method provides a robust solution against uncertainty. To reduce the computational cost, a ranking strategy and an approximation model are further involved to do a preliminary screening. By this means, the robust design can generate an improved arch dam structure that ensures both safety and serviceability during its lifetime.

关键词: arch dam     shape optimization     robust optimization     load uncertainty     approximation model    

Prediction of bed load sediments using different artificial neural network models

Reza ASHEGHI, Seyed Abbas HOSSEINI

《结构与土木工程前沿(英文)》 2020年 第14卷 第2期   页码 374-386 doi: 10.1007/s11709-019-0600-0

摘要: Modeling and prediction of bed loads is an important but difficult issue in river engineering. The introduced empirical equations due to restricted applicability even in similar conditions provide different accuracies with each other and measured data. In this paper, three different artificial neural networks (ANNs) including multilayer percepterons, radial based function (RBF), and generalized feed forward neural network using five dominant parameters of bed load transport formulas for the Main Fork Red River in Idaho-USA were developed. The optimum models were found through 102 data sets of flow discharge, flow velocity, water surface slopes, flow depth, and mean grain size. The deficiency of empirical equations for this river by conducted comparison between measured and predicted values was approved where the ANN models presented more consistence and closer estimation to observed data. The coefficient of determination between measured and predicted values for empirical equations varied from 0.10 to 0.21 against the 0.93 to 0.98 in ANN models. The accuracy performance of all models was evaluated and interpreted using different statistical error criteria, analytical graphs and confusion matrixes. Although the ANN models predicted compatible outputs but the RBF with 79% correct classification rate corresponding to 0.191 network error was outperform than others.

关键词: bed load prediction     artificial neural network     modeling     empirical equations    

A method to predict cooling load of large commercial buildings based on weather forecast and internal

Junbao JIA,Jincheng XING,Jihong LING,Ren PENG

《能源前沿(英文)》 2016年 第10卷 第4期   页码 459-465 doi: 10.1007/s11708-016-0424-8

摘要: Considering the fact that customers of large commercial buildings have the characteristics of the higher density and randomness, this paper presented an air-conditioning cooling load prediction method based on weather forecast and internal occupancy density. The multiple linear feedback regression model was applied to predict, with precision, the air conditioning cooling load. Case analysis showed that the largest mean relative error of hourly and the daily predicting cooling load maximum were 18.1% and 5.14%, respectively.

关键词: commercial building     load prediction     multiple linear regression    

新型网络架构发展研究

欧阳曼,刘江,廖新悦,黄韬

《中国工程科学》 2022年 第24卷 第4期   页码 12-21 doi: 10.15302/J-SSCAE-2022.04.002

摘要:

通信产业是建设网络强国、引领科技创新、驱动经济社会转型发展的重要力量;新型网络架构是未来网络与通信产业的核心内容,开展技术发展研究具有迫切性。本文阐述了新型网络架构内涵及代表性架构,涵盖信息中心网络、可表述网络、低轨卫星网络、服务定制网络、全维可定义网络、多模态网络,梳理了包括政策法规、行业发展、面临挑战在内的新型网络架构发展态势;提炼了确定性网络、分段路由、云计算与云网融合等关键技术以及加强科技专项牵引、推动应用示范等攻关重点举措。研究建议,加强政策、法律、监管方面的统筹实施,培育新型网络架构产业的良性发展生态,推动“产学研”深度合作与军民功能结合发展,构建综合创新的人才队伍与科研团队。

《一、 前言》

一、 前言

通信产业是引领科技创新、驱动经济社会转型发展的核心力量,也是建设科技强国、网络强国的核心支撑。发展通信产业对于促进现代化、工业化发展,培育和壮大战略性新兴产业,提高国家通信安全保障能力及国际竞争力都具有重要意义。随着互联网承载的服务类型快速增加,网络已不仅是数据传输通道,更成为采集、传输、存储、处理于一体的信息平台,相关的新技术、新架构、新应用蓬勃发展。卫星通信、光纤通信、第五代移动通信(5G)、虚拟现实 / 增强现实(VR/AR)等技术和场景,也为通信服务业的创新发展提供了新增支持。

伴随着新型网络的快速发展态势,网络架构与技术的需求也趋向多样化。在网络的发展与创新过程中,曾有两个阶段性的问题始终约束着行业发展。① 互联网协议(IP)地址枯竭问题,可采用无分类域间路由选择技术(CIDR)[1]、互联网协议第6版(IPv6)技术 [2] 来解决:前者通过引入网络前缀的概念来划分超网,从而进行路由聚合并减少路由表项;后者则通过IP编码地址空间增加至128位来增加IP地址数量。然而IPv6技术出现后还未实现大规模部署,也无法在体系架构层面解决原有问题。② 为了解决网络流量激增、路由表条目爆炸式增长等问题,内容分发网络(CDN)[3] 通过多地区部署缓存节点的方式来减少网络转发流量;但节点部署成本昂贵,仅能对特定业务流量进行优化,不足以成为普适性的解决方案。对网络进行“打补丁”式的改进措施,在使网络逐渐臃肿的同时,无法从根本上解决制约网络发展的关键问题。

当前,世界各国都在积极发展网络通信领域的未来关键技术,通信产业正处于“承前启后”关键时期。着眼未来需求的新型网络架构与技术受到了学术界、产业界的普遍关注。诸如信息中心网络(ICN)、软件定义网络(SDN)、云计算与白盒等新型网络架构和技术,渐渐进入了全球网络通信产业的生态链;相关的研究和创新在“竞争与合作”的理念下迅速发展,逐渐形成国际性的产业浪潮 [4]。新型网络架构与通信技术不仅具有颠覆性,而且支持涌现许多新的模式、应用和产业,将引发新一轮产业技术革命甚至成为经济发展的主要动力。针对于此,本文以新型网络架构、网络和通信技术未来发展为研究切入点,梳理当前形势与需求,阐述典型网络架构、关键技术及解决举措,以期为通信产业和网络技术的宏观研究提供基础参考。

《二、 新型网络架构的内涵与主要形式》

二、 新型网络架构的内涵与主要形式

《(一) 新型网络架构的内涵》

(一) 新型网络架构的内涵

新型网络架构指依托未来新型网络与通信领域中具有重大变革前景的相关技术而形成的体系,作为战略性新兴产业的重要发展方向,具有敏捷感知、便捷管控、优质服务、灵活可扩展等新特征,将对智能制造、物联网(IOT)、天地融合网络等技术领域产生深刻影响。

新型网络架构体系的核心在于,设计一种高效率、可扩展、大规模的通用基础网络架构,支持异构网络技术融合。现有方案主要分为“演进式”“革命式”技术路线:对于前者,研究人员主张对现有网络架构进行“修补”(如改造网络设备或拓扑结构,更新现有网络通信协议,将人工智能(AI)、区块链、大数据等新技术应用于现有网络),可暂时解决当前网络中出现的各种问题,使得现有网络架构在一定程度上适应新的发展要求;对于后者,研究人员主张重新设计网络的策略,寻求全新的网络架构并重新设计网络协议 [5],以此充分适应未来的发展要求。

也要注意到,“革命式”技术路线可更好满足未来网络的需求,但实施难度相对大;“演进式”技术路线易于部署,但将使网络趋于臃肿。就已有的新型网络架构来看,信息中心网络(ICN)、可表述网络(XIA)等属于“革命式”方案;低轨卫星网络、服务定制网络(SCN)、全维可定义网络、多模态网络等属于“演进式”方案。

《(二) 代表性的新型网络架构》

(二) 代表性的新型网络架构

《1. 信息中心网络》

1. 信息中心网络

ICN架构的设计初衷是更好地支持内容分发,采取以内容命名方式来替代以地址为中心的传统网络通信模型(见图1);能够实现用户对信息的搜索与获取,增强互联网的安全性,支持移动性应用需求,提高数据分发和收集能力。集中式ICN架构采用扁平化的命名方式,即在名字中嵌入内容的哈希,不可读的名字需要通过集中的名字解析服务来获得路由和转发路径。分布式ICN架构采用分层的命名方式,类似于统一资源定位符的结构;分层根路径为内容发布者的名字前缀,直接基于内容名字路由,不存在任何解析过程。

《图1》

图1 ICN架构的基本模式

《2. 可表述网络》

2. 可表述网络

XIA架构可提供多样化的网络使用模式来满足可靠通信服务需求,同时有效协调各方来共同提供网络服务(见图2),具有可演进、可信任、灵活路由等特点。将网络中的发送方或接收方均视作通信主体;对于不同的通信主体,路由器使用不同的处理方式来实现不同的网络功能;同一个应用可以包含多个不同的通信主体,据此实现多种网络功能 [6]。

《图2》

图2 XIA网络架构

《3. 低轨卫星网络》

3. 低轨卫星网络

低轨卫星网络系统包含空间段、地面段、用户段(见图3)。空间段分为低轨卫星和星间链路,采用星上处理技术支持星上独立组网与路由;地面段分为信关站、网控中心等,实现系统运维、与地面通信网络互联等功能;用户段涵盖各类地面终端用户,如车载终端、舰载终端、卫星电话等。低轨卫星网络具有空间跨度大、覆盖范围广、抗毁能力强等优势,加之低轨卫星的轨道高度低、传输延时短、路径损耗小,由多卫星组成的星座可以实现真正意义上的全球宽带卫星服务能力。

《图3》

图3 低轨卫星网络架构

《4. 服务定制网络》

4. 服务定制网络

SCN主要采用SDN技术,不仅能发挥SDN数据面与控制面解耦、网络可编程的突出优势,而且可根据当前网络的实际情况来提高网络虚拟化与内容智能调度等能力 [7]。大数据分析和AI技术也可为网络信息调度、智能管理等提供有效支持。SCN架构的应用有望适应互联网业务快速发展、流量快速增长、用户需求差异化、实体经济与互联网融合等实际需求,我国已制定SCN总体方案(见图4)。

《图4》

图4 服务定制网络框架

《5. 全维可定义网络》

5. 全维可定义网络

全维可定义网络架构以SDN、网络功能虚拟化(NFV)等作为技术创新基础,利用软件定义路由、软件定义互联、软件定义硬件、软件定义协议、软件定义芯片等模块来获得基础网络的拓扑结构、协议、软 / 硬件及接口的完整定义;形成开放网元设备、开放协议控制、开放网络资源、开放节点容量、开放网络接口、开放路由控制、开放存储方法等模式 [8],为用户自主定义应用提供精细化、多样化的服务(见图5)。全维可定义网络架构还为打破封闭式垄断、消除技术障碍、改造网络基础设施、测试并应用网络架构等提供了基本环境。

《图5》

图5 全维可定义网络

《6. 多模态网络》

6. 多模态网络

多模态网络架构建立全维度可定义、灵活且通用网络结构,使得网络从底层到上层的功能能以多模态方式呈现(见图6)[8],由此消除现有网络基础架构、相关技术体系所存的网络结构僵化、IP承载单一、未知威胁难以抑制等基础性问题。在多模态智慧网络模型中,数据层采用软件定义互连 / 转发技术,提高全维可定义的灵活性与可编程性;控制层主要针对不同业务的差异化服务质量要求,实现软件定义的多模态寻址与路由等功能;服务层结合对用户及业务的细粒度感知、适配拟合,实现软件定义资源管理与功能编排,支撑网络智能决策。

《图6》

图6 多模态智慧网络模型

《三、 新型网络架构发展态势》

三、 新型网络架构发展态势

《(一) 政策法规》

(一) 政策法规

新型网络架构技术对经济社会发展将产生重大影响。各国积极发布政策和法规,以引导相关技术的突破与应用,从而引发新一轮全球信息网络、通信技术的激烈竞争。在美国,战略与预算评估中心提出了以“马赛克战”为依托来实现“决策中心战”的概念构想(2020年),用于解决“网络中心战”在强对抗环境下的战术通信网络受限问题;国防部高级研究计划局启动了PRONTO网络研究项目(2021年),旨在发展网络细粒度可见、可验证、可闭环控制的“网络试验床”,用于支撑各类科学研究和试验并推动网络技术创新。欧盟H2020计划组提出了多种网络新型架构:CORRELATION项目开展了未来切片与网络服务级别流量的表征和预测,PRISENODE项目针对软件定义的雾数据中心隐私和安全感知问题提出解决方案,SEMANTIC项目研究具有移动边缘云的新一代蜂窝网络端到端切片和数据驱动自动化。

与新型网络的国际进展相对应,我国推出多项政策和规划以积极参与领域的国际竞争与合作。2020年起,我国加速开展新型网络架构相关的创新研究与建设示范,以5G、数据中心、工业互联网等为重点内容。《中华人民共和国国民经济和社会发展第十四个五年规划和2035年远景目标纲要》提出,强化国家战略科技力量,重点发展信息通信技术,引领各项技术创新发展 [9]。

《(二) 行业发展》

(二) 行业发展

网络发展水平较高的国家都在国家战略层面重视未来网络的创新。美国、欧盟、日本、韩国等国家和地区在网络创新环境、新型体系架构、新型网络技术等方面实施了众多研究项目。在网络创新环境方面,美国国家科学基金会提出全球网络创新环境项目(2005年)[10],构建了新型、安全、广泛连接的互联网,以之为实验环境开展了全球性的大规模实验;欧盟在第七框架计划中设立了未来网络研究与实验项目(2007年)[11],在物理和虚拟网络测试环境中验证了网络体系结构及协议。新型网络体系架构包括ICN、SDN等,新型网络技术涉及NFV、大数据 / 云计算 / 边缘计算等。

我国的科技公司积极围绕新型网络架构及技术开展应用研究。中国电信集团有限公司重点关注网络重构,推进云网协同规模扩张,持续扩大网络覆盖范围。中国移动通信集团有限公司关注新一代网络架构设计,重点在于全面实现网络功能优化(如流量调度、网络组网设计)。深圳市腾讯计算机系统有限公司推出了数据中心网络架构5.0版本,引入SDN/NFV技术为私有云客户提供多样化、可定制服务。阿里巴巴集团控股有限公司通过“阿里云”布局边缘计算产业,以“云+边+端”一体的计算模式作为核心发展路径。华为技术有限公司的网络侧部署以全面云化为目标,推进SDN/NFV与网络云化。

未来网络试验设施项目是我国通信与信息领域建设的国家重大科技基础设施,保持开放、易使用、可持续发展、大规模通用等特色,为研究未来网络创新体系结构提供简单、高效、低成本的试验验证环境。面向2035年的多模态智慧网络体系,通过各种网络模态间的互联互通、协同组合、无缝切换,提高网络服务的多元化能力以及对于用户需求的个性化适应能力 [12]。

《(三) 面临挑战》

(三) 面临挑战

客观来看,我国新型网络架构技术领域在深入发展和高效实施方面仍面临一些挑战。在统筹规划方面,当前的网络架构部署整体缺乏综合协调和整体规划。不少地方、行业都在自行开展研发工作,而产业界没有就新型网络架构发展形成共识,统一通用的行业认识、思路、建设方案等也有待形成。国家层面尚未形成促进新型感知网络基础设施建设的指导意见,相关的布局、建设、保护以及各类设施之间的协调发展等缺乏总体设计。这些问题的解决,需要政策法规的引导支持和标准制定的适时推进。

在产业技术方面,我国在硬件、计算机、通信网络方面的核心技术滞后于发达国家,导致新型网络架构的技术支撑作用未能有效发挥;在作为互联网核心技术的IP协议等技术方向,已有多年未获得新进展。产业基础相对薄弱,关键技术与核心软件依赖外部供应,存在着受制于人的风险。解决产业技术短板和关键技术不足的问题,离不开加快提升自主创新能力。

《四、 新型网络架构关键技术与攻关举措》

四、 新型网络架构关键技术与攻关举措

《(一) 新型网络架构关键技术》

(一) 新型网络架构关键技术

未来网络的典型场景包括消费互联网(如VR/AR、三维视频通话、全息图像、交互式游戏),工业互联网(如精仪制造、远程工控、数字孪生),车联网(如自动驾驶、车路协同)等。这些场景及应用的出现,要求新型网络架构体系具有敏锐的感知能力、灵活的路由能力、简单的网络操作能力、便捷的管控能力。建立融合、可扩展的新型网络感知体系,可支持网络环境革新,表现出更高的速率、更低的时延、可控的时延抖动、更低的丢包率、更灵活的业务部署能力。

《1. 确定性网络技术》

1. 确定性网络技术

网络技术蓬勃发展,网络业务需求也出现显著变化。用户、业务的多样化和不确定性,用户位置的不断移动,业务量的强突发性等因素,使得多维网络资源及网络状态也是动态变化的。因此,研究确定性网络技术来保障网络的确定性,将提高网络资源的利用率和业务服务质量。

确定性网络技术按协议层次可分为3类(见图7)。① 物理层采用灵活以太网(FlexE)技术,在以太网数据链路层和物理层之间的中间层增加FlexE垫片层,解耦业务速率和物理通道速率;通过物理层与数据链路层协同调度,基于时隙交换来保障时延,目前主要用于5G承载网场景。② 数据链路层采用时间敏感型网络(TSN)标准,目前主要用于工厂内网 / 车内网络等场景,包含3个主要方面:对时间同步的要求高,网络中的所有设备需要实现精确时间同步来协商时间界限;采用调度和流量整形(门控)技术,高效调度并整合具有不同的带宽及端到端延迟需求的流量类别;利用多条路径实现故障排除,预防硬件或网络故障,支持通信路径的选择、预留和容错。③ 网络层采用确定性网络(DetNet)技术,在统计复用的基础上提供确定性时延和抖动,支持集中控制、显性路由、抖动消减、拥塞保护、多径路由等功能。

《图7》

图7 确定性网络技术架构示意图

《2. 分段路由技术》

2. 分段路由技术

分段路由是骨干网SDN化的代表性技术,优势在于骨干级别的可扩展性,可解决现有IP和多协议标签交换在简化网络、灵活可控方面的难题,获得电信运营商的充分认可。分段路由技术在分布式智能、集中式优化之间寻求平衡,具有使能增强的数据包转发功能,支持网络通过特定的转发路径来传输单播分组(而不是分组通常采用的最短路径优先算法)。

分段路由是源路由机制的范例,节点通常既可以是路由器也可以是交换机。可信服务器或在管理程序上运行的虚拟转发器,通过有序指令列表(称为分段标签)来对分组进行操作。分段标签分为局部标签、全局标签,可以表示某一个拓扑或某一种指令。此外,分段路由可通过指定路径进行数据转发,从而对中间节点屏蔽相关信息,仅在入口节点的分段路由网络制定每条信息流的状态。为了与现代IP网络对齐,分段路由应用了支持等价路由的协议,即数据转发可以使用网络中所有可能的路径。

《3. 云计算与云网融合技术》

3. 云计算与云网融合技术

网络与通信技术具有高度的响应能力和敏捷性,才能支持快速变化的业务需求。云计算通过端到端整体方案,为客户提供更低时延、更高带宽、更低成本的业务体验,快速响应用户请求并提升服务质量 [13];使电信运营商能够应对用户需求,提供高质量服务,促进电信运营商网络和企业业务的深度融合。云计算平台提供了新的消费模式,即企业可按需采购计算资源并将基础设施的管理工作委托给云服务提供商。

云网融合指将网络资源与云资源进行统一定义与编排,支撑全网的敏捷资源感知、统一质量保障、弹性规划及管理,可为网络提供更为便捷、灵活的连接能力;通过实施虚拟化、一体化的技术架构融合,合理封装并统一编排资源,为实现简单、开放、融合、智能的新型信息基础设施建设筑牢基础。从宏观角度看,云网融合是新型信息基础设施的深刻变革形式,内涵在于通过云网技术和生产组织方式的全面融合与深入创新,保障社会数字化转型 [14]。

云网切片技术被视为由计算、网络、存储资源组成的端到端基础设施,在云网融合的云资源、网络资源的分配与隔离方面应用潜力良好。网络切片指将物理网络划分为多个逻辑独立的虚拟网络,虚拟网络根据不同的服务需求(如时延、带宽、安全性、可靠性等)进行独立设定,以灵活适应不同的网络应用场景。云网切片在网络切片的基础上,结合不同业务所需的网络特征、不同流量流向所产生的网络实时需求、云资源的动态变化情况,将云资源与网络资源进行协同一体化的管理、调度、优化,实现云网资源的端到端统一与隔离预留、云网连接的自动化建立与优化、云网服务能力的自动化供给。

云网切片技术的具体实现分为资源统一编排、云网感知、自适应调整。资源统一编排将云网资源进行统一抽象化管理和网络能力封装,从复杂的物理网络中抽象出简化的逻辑网络设备和虚拟网络服务。云网感知采用异构资源的多样化感知采集方式,实现云网业务、网络质量的实时获取。自适应调整进一步开展云网服务的自动化调整、优化和调度。

《(二) 实施关键技术攻关的重要举措》

(二) 实施关键技术攻关的重要举措

《1. 加强科技专项牵引》

1. 加强科技专项牵引

新型网络架构的快速发展需要与国家重大科研项目相结合。在产业建设方面,① 实施产业核心技术攻关,形成配置灵活、扩展性强的未来网络产业生态链,致力构建“芯片 ‒ 设备 ‒ 网络架构 ‒ 核心技术 ‒ 试验设施 ‒ 应用示范”的未来网络研发新模式;② 科研项目应与基础设施建设需求高度融合,重大科技项目的产出成果率先应用于城市网络通信建设,在骨干网引入SDN技术,在城域网核心层进行SDN改造以优化流量,构建统一智能管控体系和能力开放平台;③ 加快发展基于IPv6的新一代互联网,合理加大网络、终端、软件系统等的改造升级力度,推动IPv6平滑演进与规模化商用,发挥新一代互联网城市建设的示范效应,提升IPv6用户普及率与网络接入覆盖率,争取在信息通信网络基础设施水平方面保持国际领先水平。

在科技创新方面,① 提升重大原始创新和关键核心技术攻关能力,协同推进原始创新和引进消化吸收再创新,实施科技成果转化行动计划,持续推动高新技术成果产业化;② 积极推进信息通信技术人才的培养与选拔,加快构建具有全球竞争力的信息通信业人才制度体系,鼓励“产学研”对接,推动建立多方联合培养机制,大幅提升自主创新能力,加速科技成果落地转化。

在建设新型网络架构的同时,重点提升卫星通信、光纤通信、SDN、AI等网络与通信相关技术,以技术突破带动产业发展,支持网络结构快速转型;赋能现有网络设施,从简单链接型网络向智慧可控型网络演进升级,为消费型互联网、工业互联网、IoT、5G/ 第六代移动通信(6G)、军民功能结合网络、卫星互联网等产业建设打下坚实基础,促进网络架构演进与网络技术创新融合发展。

着眼我国新型网络架构的发展实际,可将新型网络架构的发展需求与重点科研项目相结合,建设本土化的网络试验平台,开展新型网络体系架构与网络技术的验证;加强企业与技术研究部门的交流合作,为科研成果转化、应用示范验证提供充分的基础条件。

《2. 推动应用示范验证》

2. 推动应用示范验证

科学技术创新的落脚点是产业发展建设。未来网络架构的研发和创新,既是提升区域技术水平和核心竞争力的关键组成部分,又是支持数字经济与信息社会发展、增强国民经济与社会保障水平的重要驱动力。发展新型感知网络基础设施产业,在前沿通信技术的基础上开展验证和示范,有利于形成技术和产业高地,建立国际竞争新优势,增强创新发展的长期动力。

在消费型互联网建设方面,随着以SDN为代表的未来网络技术趋于成熟,新型网络架构在小规模试验验证的基础上,开始在大型商用网络进行大规模部署;通过融合SDN/NFV/ 云等网络技术手段,构建可全局按需调度资源、网络能力完全开放的运营一体化网络。

在工业互联网方面,采用SDN、边缘计算、网络AI等技术架构解决网络挑战,满足工业互联网低时延、确定性时延、网络安全、网络业务定制、万亿级连接等方面需求。

在IoT方面,在前期提出的“智慧中国”概念及实践基础上,积极应用到智慧城市、智慧交通等场景构建,融入大数据、云计算等新一代信息技术,连接分布在城市区域内的大量传感器,提供智能感知、智能分析的能力;结合数据高效传输,实现无需人为干预的物与物协同工作,为数据的可靠积累、预测感知及分析确立基础。

在5G/6G建设方面,在大规模部署5G基础设施的同时,探索6G与AI、机器学习的融合,实现智能传感、智能定位、智能资源分配、智能接口切换等能力;在空间通信、智能交互、全息、触觉互联网、情感与触觉交流、虚拟助理、多感官混合现实、机器间协同、身体域网络、全自动交通等场景下开展验证和示范。

在卫星互联网方面,开展天基网络与地面网络的融合建设,实现地球近地空间中的陆、海、空、天各类用户与应用系统之间信息的高效传输与共享,为未来网络通信领域的多系统、多信息融合及协同提供重要平台;带动信息电子、卫星通信、5G等诸多方向的关键技术与产业发展,形成规模化的产业链,成为新兴产业发展示范。

《五、 我国新型网络架构发展建议》

五、 我国新型网络架构发展建议

《(一) 加强政策、法律、监管方面的统筹实施》

(一) 加强政策、法律、监管方面的统筹实施

政府对宏观产业发展引导与调控作用的发挥,需要健全的政策、法律制度体系。建立新型网络架构技术产业,尤其需要市场、融资、人才配置、重大项目实施等相关方面的政策支持和法律保障。建议加强对未来通信网络和产业发展重大问题、政策、项目的管理与协调,以管理创新促进产业应用的稳健发展。运用各类媒介资源开展科普宣传,增强社会公众对于未来信息通信网络发展的科学认识。定期检测并评价信息产业的发展趋势和技术进展,为未来互联网技术、信息通信领域的发展布局提供科学判断。

《(二) 培育新型网络架构产业的良性发展生态》

(二) 培育新型网络架构产业的良性发展生态

建议突出网络基础、核心平台、数据要素、安全保障的关键作用,支持新型网络架构的新模式发展和企业创新活跃度提升,壮大产业规模、平衡产业生态,融合各行业共识,为新型网络架构产业的高质量发展筑牢基础。培育一系列自主运营的企业级平台,构建互联网工业平台测试系统和公共服务系统,合理引导工业企业业务进入“云端”。积极发挥未来网络与通信产业的智库研究优势,以聚焦、科学的发展战略来引导行业优质发展。扩大市场开放力度,逐步形成有利于网络、平台、应用、新业态等集聚发展的良性生态环境。

《(三) 推动“产学研”深度合作与军民功能结合发展》

(三) 推动“产学研”深度合作与军民功能结合发展

依托电信运营商、设备厂商、互联网公司、科研院所、高校的各自优势资源,搭建未来网络教育平台,普及未来网络领域知识并提高全社会的创新能力。发挥科研院所、高校的技术与知识集中特色,强化企业创新主体定位,推动“产学研”深度合作,联合开展信息通信领域的技术专项研究。加强网络安全技术研发和技术手段应用,突破网络安全技术瓶颈并加快成果转化,实施关键技术产业化,支持信息通信技术在军民功能结合等方向的深化发展。

《(四) 构建综合创新的人才队伍与科研团队》

(四) 构建综合创新的人才队伍与科研团队

树立全球视野,精准引进高层次人才。围绕各级经济技术开发区的“产才融合”高地建设,强化“双招双引”机制,给予新型网络高端人才以“高端”支持;依托国家级人才计划开展新型网络架构方面的“引智”工作,丰富人才储备并优化梯队结构;构建人才引进网络,发挥用人单位主体作用,采取“刚性”“柔性”相结合的引进方式。支持高端人才围绕新型网络产业发展需要开展创新创业,健全和优化人才激励机制,合理调整科技人员股权和分红激励办法。加强新型网络科研团队建设,充分发挥科研院所、高校的人才培养作用,构建未来网络与通信领域的科研高地。

利益冲突声明

本文作者在此声明彼此之间不存在任何利益冲突或财务冲突。

Received date:April 10, 2022; Revised date: June 20, 2022

Corresponding author:Liu Jiang is a professor from the School ofInformation and Communication Engineering, Beijing University ofPosts and Telecommunications. His major research fields include futurenetwork architecture, network virtualization, software-defined network,information center network, network test environment construction, andspace satellite network. E-mail: liujiang@bupt.edu.cn

Funding project:Chinese Academy of Engineering project “Researchon the Development Strategy of the New Internet Plus Action Planunder the New Era and New Situation” (2021-XZ-24)

关键词: 新型网络架构     革命式与演进式网络     确定性网络     分段路由     云网融合    

Influence of axial load on the lateral pile groups response in cohesionless and cohesive soil

Jasim M. ABBASA,Zamri CHIK,Mohd Raihan TAHA

《结构与土木工程前沿(英文)》 2015年 第9卷 第2期   页码 176-193 doi: 10.1007/s11709-015-0289-7

摘要: The lateral response of single and group of piles under simultaneous vertical and lateral loads has been analyzed using a 3D finite element approach. The response in this assessment considered lateral pile displacement and lateral soil resistance and corresponding - curve. As a result, modified - curves for lateral single pile response were improved with respect to the influence of increasing axial load intensities. The improved plots can be used for lateral loaded pile design and to produce the group action design -multiplier curves and equations. The effect of load combination on the lateral pile group response was performed on three pile group configurations (i.e., 2×1, 2×2 and 3×2) with four pile spacings (i.e., = 2 , 4 , 6 and 8 ). As a result, design curves were developed and applied on the actual case studies and similar expected cases for assessment of pile group behavior using improved p-multiplier. A design equation was derived from predicted design curves to be used in the evaluation of the lateral pile group action taking into account the effect of axial load intensities. It was found that the group interaction effect led to reduced lateral resistance for the pile in the group relative to that for the single pile in case of pure lateral load. While, in case of simultaneous combined loads, large axial load intensities (i.e., more than 6 , where is lateral load values) will have an increase in -multiplier by approximately 100% and will consequently contribute to greater group piles capacities.

关键词: piles     pile group     spacing     configuration     combined load    

Analysis of load and adaptability of disc cutters during shield tunneling in soft–hard varied strata

《结构与土木工程前沿(英文)》 2023年 第17卷 第4期   页码 533-545 doi: 10.1007/s11709-023-0946-1

摘要: The disc cutters of shield machines exhibit unsatisfactory adaptability and performance during the soft–hard varied strata tunneling process. To analyze the rotation state, cutting performance, and adaptability of disc cutters during shield tunneling in soft–hard varied strata, the Holmquist Johnson Cook and Federal Highway Administration constitutive models are introduced to numerically simulate the failure process of materials on the excavation face and to calculate the load of disc cutters. Additionally, the parameters of the models are modified based on laboratory disc cutter excavation test results. The results of numerical calculation can reflect the load level and the behavior of the disc cutters during operation. The tangential loads of the disc cutters during the cutting of four typical soft-strata excavation face models are numerically calculated, thus providing reference values for the starting torque of the disc cutters. A greater penetration is suggested for soft-strata tunneling to allow the disc cutters to rotate smoothly and continuously as well as to guarantee a better cutting effect. The disc cutters in the center of the cutterhead should be specified with a lower starting torque to prevent uneven wear, rotation stagnation, cutterhead clogging, and other adverse phenomena.

关键词: shield tunneling     disc cutter load     laboratory excavation test     numerical calculation     soft–hard varied strata    

State identification of home appliance with transient features in residential buildings

《能源前沿(英文)》 2022年 第16卷 第1期   页码 130-143 doi: 10.1007/s11708-022-0822-z

摘要: Nonintrusive load monitoring (NILM) is crucial for extracting patterns of electricity consumption of household appliance that can guide users’ behavior in using electricity while their privacy is respected. This study proposes an online method based on the transient behavior of individual appliances as well as system steady-state characteristics to estimate the operating states of the appliances. It determines the number of states for each appliance using the density-based spatial clustering of applications with noise (DBSCAN) method and models the transition relationship among different states. The states of the working appliances are identified from aggregated power signals using the Kalman filtering method in the factorial hidden Markov model (FHMM). Thereafter, the identified states are confirmed by the verification of system states, which are the combination of the working states of individual appliances. The verification step involves comparing the total measured power consumption with the total estimated power consumption. The use of transient features can achieve fast state inference and it is suitable for online load disaggregation. The proposed method was tested on a high-resolution data set such as Labeled hIgh-Frequency daTaset for Electricity Disaggregation (LIFTED) and it outperformed other related methods in the literature.

关键词: nonintrusive load monitoring (NILM)     load disaggregation     online load disaggregation     Kalman filtering     factorial hidden Markov model (FHMM)     Labeled hIgh-Frequency daTaset for Electricity Disaggregation (LIFTED)    

Interaction behavior and load sharing pattern of piled raft using nonlinear regression and LM algorithm-based

《结构与土木工程前沿(英文)》 2021年 第15卷 第5期   页码 1181-1198 doi: 10.1007/s11709-021-0744-6

摘要: In the recent era, piled raft foundation (PRF) has been considered an emergent technology for offshore and onshore structures. In previous studies, there is a lack of illustration regarding the load sharing and interaction behavior which are considered the main intents in the present study. Finite element (FE) models are prepared with various design variables in a double-layer soil system, and the load sharing and interaction factors of piled rafts are estimated. The obtained results are then checked statistically with nonlinear multiple regression (NMR) and artificial neural network (ANN) modeling, and some prediction models are proposed. ANN models are prepared with Levenberg–Marquardt (LM) algorithm for load sharing and interaction factors through backpropagation technique. The factor of safety (FS) of PRF is also estimated using the proposed NMR and ANN models, which can be used for developing the design strategy of PRF.

关键词: interaction     load sharing ratio     piled raft     nonlinear regression     artificial neural network    

Load shedding scheme for an interconnected hydro-thermal hybrid system with SMES

D. TYAGI, Ashwani KUMAR, Saurabh CHANANA

《能源前沿(英文)》 2012年 第6卷 第3期   页码 227-236 doi: 10.1007/s11708-012-0198-6

摘要: The frequency of the power system varies based on the load pattern of the consumers. With continuous increase in the load, the frequency of the system keeps decreasing and may reach its minimum allowable limits. Further increase in the load will result in more frequency drop leading to the need of load shedding, if excess generation is not available to cater the need. This paper proposed a methodology in a hybrid thermal-hydro system for finding the required amount of load to be shed for setting the frequency of the system within its minimum allowable limits. The load shedding steps were obtained based on the rate of change of frequency with the increase in the load in both areas. The impact of superconducting magnetic energy storage (SMES) was obtained on load shedding scheme. The comparison of the results was presented on the two-area system.

关键词: critical load     frequency response     load shedding     multi-area system     rate of change of frequency     superconducting magnetic energy storage (SMES) device    

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Analysis of load and adaptability of disc cutters during shield tunneling in soft–hard varied strata

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