Massive MIMD neural network simulations: The connections dilemma

We present two strategies for the simulation of massive neural networks on message-passing MIMD machines. In the first strategy all interconnections between neurons are stored explicitly in interconnection matrices. During simulation, every processor is responsible for certain submatrices of these interconnection matrices. The fact that message-passing MIMD processors do not provide virtual memory seriously limits the size of the networks that can be simulated, since interconnection matrices require huge amounts of memory. An alternative strategy is not to store the connections explicitly, but generate the interconnections as they are needed. This circumvents memory limitations, but because interconnections need to be generated multiple times, it is inherently slower than the first implementation. This yields the connections dilemma: the choice between fast simulation of small networks as against slower simulation of massive networks. We present, analyze and bench-mark parallel implementations for both strategies. An efficient connection-look-up algorithm, which can be used for any network with static interconnections, ensures that simulation times for the second strategy are only marginally longer than for the first strategy. We show that for our users the connections dilemma is no longer a dilemma: by means of our look-up algorithm the simulation of massive networks becomes possible; furthermore the time to design and construct a network, prior to simulation, is considerably shorter than it is for the matrix version, and in addition this time is independent of network size. Although we have implemented both strategies on a parallel computer, the algorithms presented here can be used on any machine with memory limitations, such as personal computers.     

AR-CNN:an attention ranking network for learning urban perception

An increasing number of deep learning methods is being applied to quantify the perception of urban environments,study the relationship between urban appearance ...     

Optimal management of an urban road network with an environmental perspective

Within the framework of numerical simulation and optimal control of partial differential equations, in this work we deal with the mathematical modelling and optimal management of urban road networks. In particular, we are interested in finding the optimal management of the network intersections in order to reduce traffic congestion and atmospheric pollution. So, we consider two different multi-objective control problems (the former from a cooperative viewpoint, the latter within a hierarchical paradigm), propose a complete numerical algorithm to solve them, and, finally, present several numerical tests for a realistic case posed in the Guadalajara Metropolitan Area (Mexico), where the possibilities of our methodology are shown.     

Fault measurement detection in an urban water supply network

For the improvement of the performance of technical processes, faults and abnormal system operation must be detected and identified. For that purpose different approaches for fault detection have been developed and, here, a model-based approach is used. A diagnosis strategy based on fuzzy residual analysis is presented in this paper. The proposed approach uses the analytical redundancy to detect and isolate faults on sensors. After a presentation of its principle, the method is applied to an urban water supply network. Thanks to the use of fuzzy concept, the suggested diagnosis procedure enables to take into account all the available data and knowledge. Moreover, its efficiency has been proved by using experimental data. Therefore, a supervision software has been developed on the basis of this fuzzy-based fault isolation method.     

Final size of network epidemic models:properties and connections

Dear editor, The classical final size relation of the standard susceptible-infected-recovered(SIR)epidemic model is based on homogeneous-mixing population[1,2]....     

Cultural economy at work in the city of Kristiansand: cultural policy as incentive for urban innovation

In 2002, as part of its urban policy, the city of Kristiansand set up a giant foundation, for the purpose of soliciting projects, talents and strategies for growth in the citys cultural economy. There was conflict over core values in the promotion of culture and heritage, and discussion on the transformation of power and democracy. The article assesses the challenges facing the foundation Cultiva, including institutional ramifications related to régimes of public planning and governance. Cultiva introduces new discourses of culture in urban development, with impacts on both the outside perception of the city and the everyday culture among the inhabitants of Kristiansand.     

The network is the chip

A few years ago, Sun Microsystems used the slogan, "the network is the computer," to promote its products and to alert people to a profound change in computing-use models. With the growth in cell phones, digital cameras, portable music players, wireless e-mail, GPS sensors, and automotive map displays that rely on wired and wireless networks, you might be tempted to say "the network is my post office, my map, my stereo system, my photo album..." and so on.     

城市自来水供水管网地理信息系统的设计

文章介绍了城市自来水供水管网地理信息系统的设计目标和系统需求,给出了GIS系统平台选型的若干要素,详细阐述了GIS数据组织和系统设计功能。     

The Complexity of Recognition in the Single-Layered PLN Network with Feedback Connections

Regarding a single-layered PLN network with feedback connections as an associative memory network,the complexity of recognitions is discussed.We have the main result:if the size of the network N is m,then the complexity of recognition is an exponential function of m.The necessary condition under which the complexity of recognition is polynomial is given.     

The air traffic flow control problem as an application of network theory

In this paper the air traffic flow control is approached as a constrained optimization problem on a multicommodity network. The proposed dynamic mathematical model, by means of a suitable time discretization, has been changed into a “static” one, in order to use static network flow algorithms while taking into account the “unsteady” nature of the air traffic congestion problems.The complexity of the model requires some preliminary effort, such as the identification of some characteristic parameters of the system.In this paper, the network theory is applied to evaluate the influence of the time discretization interval on the model significancy with respect to the actual traffic situation. In particular, a computational example concerning the Rome air traffic control region is presented and the relative results are discussed.     

Agent-oriented design of human–computer interface: application to supervision of an urban transport network

At the present time, the approaches found in the design of interactive systems use a modular structure, with the aim of achieving a better understanding of reactivity, flexibility, maintainability and reuse at the human–machine interface level. However, most architecture models are far more concerned with user-controlled applications and they do not consider the specificities of supervision applications in which the human operator acts as the controller and commander of an independent dynamic process. A multi-agent approach is a possible answer to this type of situation. The agent-oriented model put forward in this article is the subject of an application intended in the long term to supervise the user information system of an urban transport network.     

Multidimensional urban segregation: toward a neural network measure

We introduce a multidimensional, neural network approach to reveal and measure urban segregation phenomena, based on the self-organizing map algorithm (SOM). The multidimensionality of SOM allows one to apprehend a large number of variables simultaneously, defined on census blocks or other types of statistical blocks, and to perform clustering along them. Levels of segregation are then measured through correlations between distances on the neural network and distances on the actual geographical map. Further, the stochasticity of SOM enables one to quantify levels of heterogeneity across census blocks. We illustrate this new method on data available for the city of Paris.

     

Software execution processes as an evolving complex network

Inspired by the surprising discovery of several recurring structures in various complex networks, in recent years a number of related works treated software systems as a complex network and found that software systems might expose the small-world effects and follow scale-free degree distributions. Different from the research perspectives adopted in these works, the work presented in this paper treats software execution processes as an evolving complex network for the first time. The concept of software mirror graph is introduced as a new model of complex networks to incorporate the dynamic information of software behavior. The experimentation paradigm with statistical repeatability was applied to three distinct subject programs to conduct several software experiments. The corresponding experimental results are analyzed by treating the software execution processes as an evolving directed topological graph as well as an evolving software mirror graph. This results in several new findings. While the software execution processes may demonstrate as a small-world complex network in the topological sense, they no longer expose the small-world effects in the temporal sense. Further, the degree distributions of the software execution processes may follow a power law. However, they may also follow an exponential function or a piecewise power law.     

Digital urban ambience: Mediating context on mobile devices in a city

We explore the term digital urban ambience to describe the user experience of mobile devices mediating context in metropolitan areas. Mediated context-awareness explores a constructivist approach to context and aims to provide resources for experiencing context rather than correctly recognizing and adapting to it. Exploring this approach we have built a prototype system, eSpective₂, combining maps and augmented reality on a touch phone, and we have studied its use. We conducted a triangulated field study involving 58 participants and up to one month of use. Elaborating on the work of Thibaud (2002)  [1], the main finding is that context resources provided through mobile devices digitally contribute to the experience or feeling of urban ambience (1) by adding to the quality of the situation as a whole, (2) as a catalyst for action, and (3) as a sensory background.     

基于GIS的城乡电网管理系统

本文介绍了基于GIS的城乡电网管理系统。系统目标是完成配电自动化的设备管理和用户信息系统。系统核心和用户界面用VisualBasic编写而成;空间数据库和属性数据库分别由MapInfo和Access生成和管理;采用ADO方式连接属性数据库;将MapX控件嵌入VB,实现对图形的操作和控制。     

基于GIS的城乡电网管理系统

本文介绍了基于GIS的城乡电网管理系统.系统目标是完成配电自动化的设备管理和用户信息系统.系统核心和用户界面用Visual Basic编写而成空间数据库和属性数据库分别由MapInfo和Access生成和管理;采用AD0方式连接属性数据库;将MapX控件嵌入VB,实现对图形的操作和控制.     

Building an IP-based community wireless mesh network: Assessment of PACMAN as an IP address autoconfiguration protocol

Wireless mesh networks are experiencing rapid progress and inspiring numerous applications in different scenarios, due to features such as autoconfiguration, self-healing, connectivity coverage extension and support for dynamic topologies. These particular characteristics make wireless mesh networks an appropriate architectural basis for the design of easy-to-deploy community or neighbourhood networks. One of the main challenges in building a community network using mesh networks is the minimisation of user intervention in the IP address configuration of the network nodes. In this paper we first consider the process of building an IP-based mesh network using typical residential routers, exploring the options for the configuration of their wireless interfaces. Then we focus on IP address autoconfiguration, identifying the specific requirements for community mesh networks and analysing the applicability of existing solutions. As a result of that analysis, we select PACMAN, an efficient distributed address autoconfiguration mechanism originally designed for ad-hoc networks, and we perform an experimental study – using off-the-shelf routers and assuming worst-case scenarios – analysing its behaviour as an IP address autoconfiguration mechanism for community wireless mesh networks. The results of the conducted assessment show that PACMAN meets all the identified requirements of the community scenario.     

The influence of virtual tour on urban visitor using a network approach

Virtual tours provide an interactive experience for potential visitors, influencing the destination image and the intention to visit. However, virtual tours are limited to one-way communication, and there is a need to quantitatively analyze the influence of virtual tours based on the context of physical movement. Therefore, this study aimed to quantitatively analyze the virtual influence from a network perspective and to analyze changes in destination image and intention to visit through a two-way virtual tour. We noted that virtual tours are confirmed to improve destination image and intention to visit, and the experience of a place in Minecraft plays a mediator role in the activation of local visits. This study demonstrates that virtual tours can be a mediator to help local visits and that virtual tours affect physically marginalized. We believe these findings can be applied as practical solutions for areas with physical mobility constraints and contribute to urban visitor studies.     

不同表达粒度对城市路网结构健壮性评价的影响

城市道路网络结构的健壮性评价需要定量化分析不同类型攻击对路网结构的影响.然而,城市路网拓扑结构在不同表达粒度下具有不同特征,对各种类型攻击的敏感性也存在差异.本文对城市道路网络进行不同表达粒度下的对偶图建模,并借鉴复杂网络中基于网络结构特征刻画的持续性模拟攻击方法,通过观测随机攻击和目的性攻击过程中城市路网结构的变化过程,评估不同表达粒度对城市路网结构健壮性评价的影响.研究选择了6个不同空间形态的城市路网作为实验路网.结果表明,在相同表达粒度下,对于随机攻击或目的性攻击,不同形态的城市路网结构变化过程具有相似特征,但同一城市路网在不同表达粒度下,受到攻击时的结构演变特征有较大差异.因此面向不同应用时需要选择合适的表达粒度来评价路网健壮性.路段粒度适用于评价点状事件造成的交通中断对路网的影响,可以为突发事故应急方案的制定提供依据;路链粒度适用于评价线状事件如整条道路交通管制或改为单行线时对路网的影响,可以辅助交通管理部门制定合理的交通管制方案;社区粒度适用于评价影响范围较大的交通事件如大型文体活动等面状事件对城市交通的影响,同时该表达粒度顾及了道路交通的区域联动,更适用于动态交通环境下的路网健壮性评价.