Spatial Accessibility of Road Network in Wuhan Metropolitan Area Based on Spatial Syntax

Based on space syntax theory, the spatial accessibility of the road network in Wuhan Metropolitan Area has been quantitatively analyzed by building a series of accessibility variables. Topologic connectivity in the accessible rings appears to be broken;traffic axis network is in spatial structure of hub-and-spoke and fishbone-like. Meanwhile, the differences in classified road network have led to inefficiency of its network servo and its ever-worsening capability to respond to traffic jams. Besides, two band-like integrated cores of which one is east to west along the Yangtze River and the other is north to south along Beijing to Guangzhou Railway, have become the first level traffic axis in the whole network, which is responsible for the connectivity of the entire metropolitan area network. This consequently has strengthened the dominant position of Wuhan which is located on the bands’ crossing. In short, the spatial accessibility of that classified space morphology, the urban system, the transport infrastructure as well as the social and economic development of Wuhan Metropolitan Area are highly interrelated to each other, especially to the high level highway network featured by freeways, the development level of which is well in line with that of road network accessibility.

Simulation of Optical Packet-Switched Metropolitan Area Network

This paper introduces architectures of two types optical packet switched metropolitan area networks and their media access control protocols. We have designed related network simulation systems. With these simulation systems, the characteristics and performance of the two MANs can be achieved.

Comparison of Urban Growth Modeling Using Deep Belief and Neural Network Based Cellular Automata Model—A Case Study of Chennai Metropolitan Area, Tamil Nadu, India

Urban Growth Models (UGMs) are very essential for a sustainable development of a city as they predict the future urbanization based on the present scenario. Neural Network based Cellular Automata models have proved to predict the urban growth more close to reality. Recently, deep learning based techniques are being used for the prediction of urban growth. In this current study, urban growth of Chennai Metropolitan Area (CMA) of 2017 was predicted using Neural Network based Cellular Automata (NN-CA) model and Deep belief based Cellular Automata (DB-CA) model using 2010 and 2013 urban maps. Since the study area experienced congested type of urban growth, “Existing Built-Up” of 2013 alone was used as the agent of urbanization to predict urban growth in 2017. Upon validating, DB-CA model proved to be the better model, as it predicted 524.14 km2 of the study area as urban with higher accuracy (kappa co-efficient: 0.73) when compared to NN-CA model which predicted only 502.42 km2 as urban (kappa co-efficient: 0.71), while the observed urban cover of CMA in 2017 was 572.11 km2. This study also aimed at analyzing the effects of different types of neighbourhood configurations (Rectangular: 3 × 3, 5 × 5, 7 × 7 and Circular: 3 × 3) on the prediction output based on DB-CA model. To understand the direction and type of the urban growth, the study area was divided into five distance based zones with the State Secretariat as the center and entropy values were calculated for the zones. Results reveal that Chennai Corporation and its periphery experience congested urbanization whereas areas away from the Corporation boundary follow dispersed type of urban growth in 2017.

MULTI-AGENT SYSTEM FOR WORM DETECTION AND CONTAINMENT IN METROPOLITAN AREA NETWORKS

Active worms can cause widespread damages at so high a speed that effectively precludes human-directed reaction, and patches for the worms are always available after the damages have been caused, which has elevated them self to a first-class security threat to Metropolitan Area Networks (MAN). Multi-agent system for Worm Detection and Containment in MAN (MWDCM) is presented to provide a first-class automatic reaction mechanism that automatically applies containment strategies to block the propagation of the worms and to protect MAN against worm scan that wastes a lot of network bandwidth and crashes the routers. Its user agent is used to detect the known worms. Worm detection agent and worm detection correlation agent use two-stage based decision method to detect unknown worms. They adaptively study the accessing in the whole network and dynamically change the working parameters to detect the unknown worms. MWDCM confines worm infection within a macro-cell or a micro-cell of the metropolitan area networks, the rest of the accesses and hosts continue functioning without disruption. MWDCM integrates Worm Detection System (WDS) and network management system. Reaction measures can be taken by using Simple Network Management Protocol (SNMP) interface to control broadband access server as soon as the WDS detect the active worm. MWDCM is very effective in blocking random scanning worms. Simulation results indicate that high worm infection rate of epidemics can be avoided to a degree by MWDCM blocking the propagation of the worms.

A Three-dimensional IP-based Telecom Metropolitan Area Network Model

The Metropolitan Area Network (MAN) has faced serious problems after years of rapid development. The model of three-dimensional IP-based MAN, proposed by ZTE, is a next-generation MAN solution, which not only solves the existing problems but also brings new ideas for the development of next-generation MAN.

基于高速公路客流数据的重庆与毗邻地区联系网络空间结构研究

基于高速公路交通客流数据,采用社会网络与GIS空间分析法,以客流联系视角探讨重庆市与毗邻地区的城镇网络空间结构。结果表明:1)重庆中心城区为网络的绝对核心,长寿、江津、璧山为网络中的重要节点城市,涪陵、璧山、长寿在网络中通达性明显,涪陵、黔江、江津、万州的中介作用突出;2)重庆与毗邻地区的客流网络呈现三级轴线联系,整体网络呈现明显的放射性特征,部分地区联系突破省级行政边界,网络层级按照“4+15+18”分布;3)重庆与毗邻地区的凝聚子群表现出高度的地理邻近性,形成“核心―边缘”结构。未来重庆中心城区需进一步加强与四川东部地级市的辐射能力与交通联系,进一步培育与成都双城联系的发展轴,在远期发展中考虑纳入遵义市等地区更好融入重庆都市圈。

武汉都市圈协同创新时空特征、影响因素及对策研究

将2014—2021年分为四个时间段,构建武汉都市圈协同创新网络及影响因素模型;基于社会网络分析方法,研究武汉都市圈协同创新网络时空特征;采用QAP回归分析,探讨创新主体、经济水平、技术邻近性、地理邻近性、研发机构对武汉都市圈协同创新的影响。研究表明:武汉都市圈城市间协同创新主要表现为以武汉为中心的星型结构,其协同创新网络可分为三个梯队;创新主体、经济水平、技术邻近、研发机构对武汉都市圈协同创新网络具有显著正向影响,地理邻近仅在早期表现出正向作用。

Research on the Impact and Strategies of Rail Transit Network Integration in the Context of Metropolitan Area Development:A Case Study of the Wuhan Metropolitan Area

The metropolitan area is one of the key focal points in the construction and development of China’s new urbanization.Urban integration is an emerging trend in metropolitan areas.This paper explores the traffic demand characteristics and economic aspects of rail transit within metropolitan regions and argues that the construction of an integrated urban rail transit network is an effective approach to support their development.Rail transit in metropolitan areas offers both technical and economic advantages,improving the efficiency of time and space resource utilization,fostering economic cooperation,and ultimately contributing to an integrated development model.However,the integration of rail transit networks faces several challenges,including road network planning,technical standards,and operational organization.Using the Wuhan metropolitan area as a case study,this paper analyzes the challenges of rail transit network integration and proposes strategic solutions for development.

都市圈“三生”功能空间关联网络特征与形成机制分析——以杭州都市圈为例

研究目的:以杭州都市圈为例,探究都市圈国土空间“三生”功能空间关联网络特征及其形成机制,为促进区域国土空间功能协同提升、完善国土空间开发保护策略提供参考依据。研究方法:综合评价法、社会网络分析法、QAP回归模型。研究结果:(1)2000—2020年杭州都市圈生产功能呈现先升后降的态势,生活功能快速提升,生态功能稳中有降;生产和生态功能的空间分异特征显著,生活功能表现出日益均衡的空间分布特征。(2)研究期内,杭州都市圈生活功能网络密度持续提升,生产功能网络密度先升后降,生态功能网络密度保持稳定,在空间上形成了以杭州和绍兴主城区为核心节点的复杂、稳定的网络结构形态。(3)地理空间邻近性对“三生”功能空间关联网络的形成均产生正向影响,耕地和林地资源禀赋差异、经济发展水平差距、产业结构差异、固定资产投资差异等因素在不同程度上对“三生”功能空间关联网络的形成产生显著影响。研究结论:应以网络化思维促进都市圈“三生”功能协同提升,依托一体化建设统筹资源优化配置,并通过因地制宜、优势互补促进区域空间协调发展。

改进的DQDB MAN网络性能分析

对比分析了ＤＱＤＢ协议与改进的ＤＱＤＢ协议——具有时隙重用功能和抢占优先功能的、多请求多优先级ＢＷＢ计数器的媒质接入控制机制．分析表明，这种新方法在保持原协议特点的同时，进一步改善了网络带宽分配的性能：时隙重用使网络的吞吐率提高了近１倍；在多优先级网络中ＭＰＢＷＢ机制大大改善了高优先级业务的性能；抢占优先机制使得高优先级业务的性能不受低优先级业务的影响；发送请求窗口值则决定了暂态时间的长短，当它与ＢＷＢ－ＭＯＤ的比值相等时。

DQDBMAN带宽分配策略

分布式排队双总线（ＤＱＤＢ）协议采用带宽平衡机制（ＢＷＢ），保证了在网络重载时，在每个结点浪费掉一部分带宽的条件下，达到全网带宽分配的公平性．但它还存在着优先级管理和达到公平性稳态的时间较长等问题．在分析造成这些问题的原因的基础上，提出了一种更为有效地解决带宽分配公平性的方法，即具有时隙重用功能和抢占优先功能的、多请求多优先级ＢＷＢ计数器的媒质接入控制机制（Ｍ－ＤＱＤＢ）．这种新方法在保持原协议特点的同时。

福州都市圈市域铁路网络架构研究

[目的]为应对福州都市圈的发展要求,需构建与其他轨道交通方式高效融合的市域(郊)铁路网,大幅提升福州市中心城区与外围组团、临近郊县之间的空间效应,缩短福州都市圈内交通出行时间,满足福州都市圈主圈层1 h通勤圈的交通需求。[方法]在阐述福州都市圈社会经济及轨道交通概况的基础上,参考国内外都市圈的发展经验,对福州都市圈圈层尺度进行识别,将福州都市圈分为1个主圈层(含交通半径为40 km的通勤圈、交通半径为70 km的辐射圈)和4个次圈层。采用以“功能层次法”为基础、以“节点锚固法”+“点线面法”为支撑的技术方法,提出了福州都市圈主圈层市域铁路网络规划方案,并对该方案进行了效果评价。[结果及结论]该方案对促进福州都市圈内新型城镇化建设、拓宽中心城市发展空间、扩大城市轨道交通辐射半径、提高福州都市圈1 h通勤圈协同发展水平均具有重要的支撑意义。

武汉城市圈生态网络鲁棒性模拟及稳定性分析

生态网络在不同破坏程度或干扰强度下呈现出不同的鲁棒性,势必造成区域生态系统的稳定性风险。基于武汉城市圈生态网络的构建与识别,建立节点和廊道的重要性评价体系,运用鲁棒模型模拟随机干扰情景下的鲁棒性变化评价生态网络的稳定性特征。结果表明:基于复杂网络理论对武汉城市圈生态网络进行拓扑网络提取,共生成117个节点和189条连接线,重要性等级较高的节点占23.9%,主要分布在研究区中北部区域,重要性较低的节点占节点总数的51.3%,主要分布在研究区的西北和东南地区;采用重力模型判别生态廊道重要性,得到17条重要廊道,28条一般廊道,重要廊道对生态网络的连通性和稳定性具有极大影响;节点数量和重要度对网络的稳定性具有显著影响,当节点失效率低于50%时,生态网络稳定性变化较小,整体处于较高的稳定性;当节点失效率在50%—85%时,生态网络极其不稳定;当节点失效比率达到85%时,生态网络开始瘫痪;依据生态节点和廊道的重要性以及模拟结果,分别提出生态节点保护和廊道建设的差异化管理策略。

典型都市圈空间结构与功能网络联系的演变研究

推动都市圈发展是我国新型城镇化进入新阶段的客观趋势和必然要求,研究从形态、功能空间结构以及网络联系对我国典型都市圈展开演变分析。结果表明:(1)均为发展型的国家级都市圈表征出差异化的空间结构,如南京都市圈呈现均衡化形态空间,福州、成都、西安都市圈为单中心集聚,而长株潭都市圈呈多中心空间布局。(2)各都市圈配套功能设施供需匹配不足,资源要素分布不均。(3)多数都市圈呈现近中心城区的向心性网络联系趋势,区域网络协调初步形成。最后,基于研究分析,文章探索都市圈空间格局优化策略以及相应政策建议,推动我国都市圈高质量发展。

广佛都市区创新空间单元与创新网络研究

基于创新空间集聚创新要素的“场”空间和区域创新网络“流”节点的双重属性,提出创新空间单元概念假设。利用发明专利申请数据和空间聚类分析等方法,探究广佛都市区创新空间单元的格局与类型,以及创新网络的结构与模式。研究发现:(1)识别出58个创新空间单元,论证了概念假设;(2)广佛都市区创新空间单元呈现“一区多核多点”格局,并可分为创新城区、产业园区、混合型科技园区等三大类七小类单元类型;(3)创新空间单元网络呈现以广州中心城区为核心的“鱼骨放射状”结构,并提炼出大学研究院所产学研合作创新网络模式、龙头企业集团创新网络模式、体制内企业和机构合作创新网络模式,以及混合型创新网络模式四类典型创新网络模式。

人口流动网络嵌入视角下西安都市圈空间组织特征及规划响应

功能关联视角下,适宜的都市圈空间结构是要素自由流动与高效配置的重要支撑。文章使用手机信令数据测度跨城人口联系,基于“嵌入性”理论及网络分析方法研判西安都市圈空间组织特征。研究发现:西安都市圈尚处于极化向均衡的演化阶段,次级城市辐射能力有限,次区域人流关联特征分异显著,但部分中小城市在网络嵌入中表现出提升能级或跨界联动的潜力。在此基础上分析网络嵌入效应,提出西安都市圈未来规划及发展建议:以实际功能关联网络动态界定治理范围;基于城市单元网络嵌入特征构建网络功能体系;以局部跨城关联优化为线索,引导组群嵌入、环带成网的空间结构,并发挥嵌入治理的共识效应,实现都市圈各级城市的高效发展及整体结构的有机均衡。

基于百度指数的武汉都市圈城市网络特征研究

以武汉都市圈为研究对象,按时间序列收集整理了2015年、2017年、2019年、2021年武汉都市圈各城市间的百度指数,构建城市网络模型,运用C-Value和D-Value的层级分析、优势流分析、多云线性回归等定量分析法,剖析武汉都市圈城市网络格局演变特征及影响因素。结果表明,武汉都市圈城市间的网络联系水平差异较大,信息流的空间分布呈现出东高西低、东密西疏的非均衡特征,武汉在都市圈中的影响力和控制力极化效应明显;武汉都市圈呈现较明显的“核心-半边缘-边缘”的网络层级结构,网络联系呈现圈层渐弱且有着空间邻近效应特征;城市信息基础设施、综合经济发展水平、城市人口对武汉都市圈城市信息网络联系强度呈显著的正向作用。最后基于此研究提出了相关优化建议。

多圈层视角下北京市轨道交通发展策略研究——基于与东京都市圈的对比分析

为更好支撑新发展阶段下北京市轨道交通的规划建设,以东京都市圈与北京市的轨道交通线网为研究对象,在多尺度分析和总结东京都市圈轨道交通发展经验的基础上,梳理东京都市圈和北京市在8 km以内、8~15km、15~30km、30~50km和50km以外5个圈层的轨道交通线网规模及不同圈层的轨道交通服务水平,形成相关量化指标,并通过指标对比,总结东京都市圈和北京市不同圈层轨道交通的特征差异,最后以此为据提出北京市未来的轨道交通发展建议,以期推动北京市轨道交通高质量、可持续发展。

面向融合的新型城域网组网技术及方案

为满足云网融合新业务的泛在接入和综合承载需求,对电信基础设施运营商的现有城域网架构面临的困难与挑战进行了深入分析,研究多网融合的新型城域网组网关键技术,分析新型城域网组网技术发展趋势,探索新型城域网的组网架构,力求简洁、通用、高效、智能,保证网络性能和容量,实现业务开通的自动化和敏捷化、网络运维的智能化、业务承载的高效化和综合化。

基于WMAN的馈线快速保护实时性研究

利用纵联保护原理可以很好地解决馈线间多开关的保护定值配合问题,实用的关键是保护通信的成本。馈线快速保护对通信的实时性要求相对较低,因此可以考虑采用低成本但实时性较差的无线通信技术。提出一种宽带无线城域网(WMAN)技术的实现方案,重点对该通信方案的延时进行了分析。研究表明,通过完善网络协议,可以满足馈线快速保护的实时性要求。该方案通信的延时主要是无线网络物理层和媒体访问控制(MAC)层延时。其中,物理层延时比较确定,选择合适的标准帧长就可以满足要求;MAC层延时具有很大的不确定性,主要是带宽申请和服务调度的延时,但如果建立专门的带宽申请时隙,并将保护信息作为最高优先级服务,其延时也可以控制在较短时间。仿真计算结果证明该方案总延时在100ms之内。