轨道交通站点地区空间网络形态研究——基于广州3个地铁站域的比较分析

针对我国城市以公共交通为导向的开发(transit-oriented development,TOD)实施过程中出现的交通站点与空间形态发展耦合不足、步行环境欠佳、功能适配性存疑等问题,以广州珠江新城、公园前和长寿路3个地铁站点为例,借助空间句法比较分析站域空间网络的组构特性及其与站点布置、步行人流分布、建设强度及功能布局等的关联,考察TOD模式下站域空间形态发展的特征及规律,并对存在的问题进行厘定。结果显示:珠江新城站域街区网格化程度不足,站点与空间组构耦合互动不足;公园前站域街道网络可达性强,集聚人群活动效应明显,但当前功能布局与空间组构存在不匹配现象;长寿路站域背景网络结构连续均匀,对步行交通出行有利,但商业功能布局对小尺度组构所牵引的人流利用不足。因此,我国未来轨道交通站域建设应关注空间组构对人车流的基础决定力量,提高交通站点、功能布局与空间网络形态之间的协同。

A packet loss avoidance handoff scheme

The basic mobile IP protocol is simple but only suitable for wide area and low speed networks. In this paper, we propose a novel micro-mobile IP handoff scheme, that is the packet loss avoidance handoff scheme. By using an additional cache at the base station and distinguishing packets with packet IDs, the proposed scheme minimizes the number of lost packets during handoff. Network architecture and detailed handoff procedures are given. We also analyze the cache size at the base station, the associated network load with the handoff procedure, and the handoff delay. The scheme is investigated by computer simulations. Simulation results show that the proposed scheme is suitable for environments with fast mobility and frequent handoff.

浅谈视频会议系统的建设——广州市花都区视频会议系统建设为例

本文以广州市花都区视频会议系统建设实际案例经验来指导如何组建视频会议系统，介绍了系统建设要求、技术标准等方面尊述视频_会议系统的技术要求，基于H．323标准的视频会议系统方案，为视频会议系统的进一步建设与应用提供了理论基础。

Exact Solutions of VNE: A Survey

Network virtualization is an enabling technology of running multiple virtual networks on a shared substrate network. It aims to deal with the ossification of current network architecture. As a crucial component of network virtualization, virtual network embedding(VNE) can efficiently and effectively allocates the substrate resource to proposed virtual network requests. According to the optimization strategy, VNE approaches can be classified into three categories: exact, heuristic and meta-heuristic solution. The VNE exact solution is the foundation of its corresponding heuristic and meta-heuristic solutions. This paper presents a survey of existing typical VNE exact solutions, and open problems for the future research of VNE exact solutions are proposed.

Joint Resource Allocation Using Evolutionary Algorithms in Heterogeneous Mobile Cloud Computing Networks

The problem of joint radio and cloud resources allocation is studied for heterogeneous mobile cloud computing networks. The objective of the proposed joint resource allocation schemes is to maximize the total utility of users as well as satisfy the required quality of service(QoS) such as the end-to-end response latency experienced by each user. We formulate the problem of joint resource allocation as a combinatorial optimization problem. Three evolutionary approaches are considered to solve the problem: genetic algorithm(GA), ant colony optimization with genetic algorithm(ACO-GA), and quantum genetic algorithm(QGA). To decrease the time complexity, we propose a mapping process between the resource allocation matrix and the chromosome of GA, ACO-GA, and QGA, search the available radio and cloud resource pairs based on the resource availability matrixes for ACOGA, and encode the difference value between the allocated resources and the minimum resource requirement for QGA. Extensive simulation results show that our proposed methods greatly outperform the existing algorithms in terms of running time, the accuracy of final results, the total utility, resource utilization and the end-to-end response latency guaranteeing.

Horizontal-Based Orchestration for Multi-Domain SFC in SDN/NFV-Enabled Satellite/Terrestrial Networks

It's promising to use Software-Defined Networking(SDN) and Network Functions Virtualization(NFV) to integrate satellite and terrestrial networks. To construct network service function chains in such a multi-domain environment, we propose a horizontal-based Multi-domain Service Function Chaining(Md-SFC) orchestration framework. In this framework, multi-domain orchestrators can coordinate with each other to guarantee the end-to-end service quality. Intra-domain orchestrators also coordinate SDN controllers and NFV management components to implement intra-domain service function chains. Based on this, we further propose a heuristic SFC mapping algorithm with a cooperative inter-domain path calculation method to map service function chains to infrastructures. In this method, master multi-domain orchestrator and intra-domain orchestrators coordinate to select proper inter-domain links. We compare the cooperative method with a naive uncooperative way that domains' topology information is provided to the master multi-domain orchestrator and it calculates the shortest inter-domain path between intra-domain service function chains directly. Simulation results demonstrate that our solution is feasible. It is able to construct end-to-end performance guaranteed service function chain by horizontal-based cooperation. The cooperative inter-domain path calculation method decreasesthe mapping load for the master orchestrator and gets the same end-to-end performance.

Simulation of Morphologies and Mechanical Properties of A/B Polymer Blend Film

The effects of blend composition and micro-phase structure on the mechanical behavior of A/B polymer blend film are studied by coupling the Monte Carlo(MC) simulation of morphology with the lattice spring model(LSM) of micro mechanics of materials.The MC method with bond length fluctuation and cavity diffusion algorithm on cubic lattice is adopted to simulate the micro-phase structure of A/B polymer blend.The information of morphology and structure is then inputted to the LSM composed of a three-dimensional network of springs to obtain the mechanical properties of polymer blend film.Simulated results show that the mechanical response is mainly affected by the density and the composition of polymer blend film through the morphology transition.When a force is applied on the outer boundary of polymer blend film,the vicinity of the inner cavities experiences higher stresses and strains responsible for the onset of crack propagation and the premature failure of the entire system.

Self-Organized Criticality Analysis of Earthquake Model Based on Heterogeneous Networks

The original Olami-Feder-Christensen （OFC） model, which displays a robust power-law behavior, is a quasistatic two-dimensional version of the Burridge-Knopoff spring-block model of earthquakes. In this paper, we introduce a modified OFC model based on heterogeneous network, improving the redistribution rule of the original model. It can be seen as a generalization of the originM OFC model We numerically investigate the influence of the parameters θandβ, which respectively control the intensity of the evolutive mechanism of the topological growth and the inner selection dynamics in our networks, and find that there are two distinct phases in the parameter space （θ,β）. Meanwhile, we study the influence of the control parameter a either. Increasing a, the earthquake behavior of the model transfers from local to global.

Structural Damage Assessment by an Embedded Fiberoptic Sensor Array and Its ANN Signal Processor

A novel type of two-dimensional damage assessment system for real time monitoring the structural health of composite structure is described. The configuration of the embedded fiberoptic sensor array and the model of the artificial neural network (ANN) are discussed. The experimental system and results show that the system can monitor a damage of structures with potential application in areas such as space aeronautics, civil engineering, etc.

Self-organized ordering of earthquakes(M≥8) in China's Mainland

The paper presented a new regular pattern （network structure ） of great earthquakes occurred in China's Mainland during the past 700 years, which may be helpful to improve the understanding of great earthquakes and can serve as a base for the study of prediction of future great earthquakes. It can be done because there are quite complete and confident records of historical and recent earthquakes in a wide extent in China.

Examples of Cable-Bar Modular Structures Based on the Class-Theta Tensegrity Systems

The relationship between forms and forces is one of the main topics of structural morphology. This harmonious coexisting link is very strong for systems in tensegrity state, commonly called ＂tensegrity systems＂. It is currently apparent that, among the tensegrity systems, there also exist cable-bar cells with a discontinuous network of cables. It is possible to design a separate set of cables inside the cable-bar elementary cell and to establish a self-stress state of equilibrium. In this connection, the author of this paper suggested to assume a new Class-Theta tensegrity systems. Each of the basic tensegrity systems termed Class-Theta possesses an external and internal set of tension components. The shape of Greek capital letter 69 （Theta） reflects two sets of such components （two sets of tendons, cables, etc.）. This notation corresponds to Skelton＇s Class-k tensegrity structure. As shown in this paper, the Class-Theta tensegrity cell can exemplify a geometrically and practically useful form for the lightweight and long-span modular structures, mainly but not only in view of civil engineering and architecture.

A Weighted Evolving Network with Community Size Preferential Attachment

Community structure is an important characteristic in real complex network.It is a network consists ofgroups of nodes within which links are dense but among which links are sparse.In this paper, the evolving network includenode, link and community growth and we apply the community size preferential attachment and strength preferentialattachment to a growing weighted network model and utilize weight assigning mechanism from BBV model.Theresulting network reflects the intrinsic community structure with generalized power-law distributions of nodes'degreesand strengths.

Capillary shrinkage of graphene oxide hydrogels

Conventional carbon materials cannot combine high density and high porosity,which are required in many applications,typically for energy storage under a limited space.A novel highly dense yet porous carbon has previously been produced from a three-dimensional(3D)reduced graphene oxide(r-GO)hydrogel by evaporation-induced drying.Here the mechanism of such a network shrinkage in r-GO hydrogel is specifically illustrated by the use of water and 1,4-dioxane,which have a sole difference in surface tension.As a result,the surface tension of the evaporating solvent determines the capillary forces in the nanochannels,which causes shrinkage of the r-GO network.More promisingly,the selection of a solvent with a known surface tension can precisely tune the microstructure associated with the density and porosity of the resulting porous carbon,rendering the porous carbon materials great potential in practical devices with high volumetric performance.

AtGGM2014, an Arabidopsis gene co-expression network for functional studies

Gene co-expression networks provide an important tool for systems biology studies. Using microarray data from the Array Express database, we constructed an Arabidopsis gene co-expression network, termed At GGM2014, based on the graphical Gaussian model, which contains 102,644 co-expression gene pairs among 18,068 genes. The network was grouped into 622 gene co-expression modules. These modules function in diverse house-keeping, cell cycle, development, hormone response, metabolism, and stress response pathways. We developed a tool to facilitate easy visualization of the expression patterns of these modules either in a tissue context or their regulation under different treatment conditions. The results indicate that at least six modules with tissue-specific expression pattern failed to record modular regulation under various stress conditions. This discrepancy could be best explained by the fact that experiments to study plant stress responses focused mainly on leaves and less on roots, and thus failed to recover specific regulation pattern in other tissues. Overall, the modular structures revealed by our network provide extensive information to generate testable hypotheses about diverse plant signaling pathways. At GGM2014 offers a constructive tool for plant systems biology studies.

Examining brain structures associated with attention networks in a large sample of young adults: a voxel-based morphometry study

Attention networks have three principal com- ponents supported by separate subprocesses, which include alerting, orienting, and executive control （EC） networks. Efficiently and accurately extracting useful information from the environment as the function of attention is pivotal to our survival. Previous brain imaging studies have examined activation patterns underlying the different attention networks in different cortical regions, yet focal differences in brain structures related to attention network components were not well understood. Therefore, in this study, voxel-based morphometry was used to investigate the relationship between gray matter volume （GMV） and different attention networks in a large young adult sample （n = 156）. As a result, multiple regression analysis revealed that higher alerting scores （stronger alerting ability） were negatively significantly correlated with region gray matter volume （rGMV） cingulate cortex/precuneus）, in the PCC/PreCu （posterior which might be associated with continuous maintenance of a vigilant state. Then, lower EC scores （stronger conflict resolution ability） were associated with larger rGMV in the dorsal anterior cingu- late cortex, which might be related to high-efficiency executive control processing. Together, findings of the present study provided a unique structural basis of GMV for individual differences in alerting and EC networks.