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Transport Networks (transport + network)
Kinds of Transport Networks Selected AbstractsA Versatile Transport Network for Sequestering and Excreting Plant Glycosides in Leaf Beetles Provides an Evolutionary Flexible Defense StrategyCHEMBIOCHEM, Issue 13 2009Sabrina Discher No abstract is available for this article. [source] Multi-level Environmentalism and the European Union: The Case of Trans-European Transport NetworksINTERNATIONAL JOURNAL OF URBAN AND REGIONAL RESEARCH, Issue 1 2006HEIN-ANTON VAN DER HEIJDEN In the European Union, trans-European transport networks (TENs) are a vital element in the constitution of one European space in order to enable the free movement of people and goods throughout the Union. Their construction, however, often causes environmental degradation. Opposition to EU politics is mostly voiced at the level of individual nation-states. As the case of TENs reveals, however, protest against European policy projects with environmental side effects can take the form of ,multi-level environmentalism', linking lobbying and ,conscientization' in Brussels with direct action at the national and local levels. Civil society theory, social movement theory and governance theory help ensure a theoretically informed answer to the question of how the resistance to TENs is organized and framed. By questioning dominant problem definitions and solution strategies, environmental movements and movement organizations, both in Brussels and in the individual nation-states, point to the possibility of looking at social and political reality from another, non-hegemonic point of view. In this way, they contribute to challenging the often biased technocratic, growth-oriented character of the European Union. [source] Traffic analysis in optical burst switching networks: a trace-based case studyEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 7 2009Ahmad Rostami Optical burst switching (OBS) appears as a promising technology for building dynamic optical transport networks. The main advantage of OBS is that it allows for dynamic allocation of resources at sub-wavelength granularity. Nevertheless, the burst contention problem, which occurs frequently inside the network, has to be addressed before OBS can be really deployed as the next generation optical transport network. Recently a lot of attention is devoted to different approaches for resolving contentions in OBS networks. Although performance analysis of these approaches is strongly dependent on the traffic characteristics in the network, the majority of the studies is so far based on very hypothetical traffic assumptions. In this study we use traces of real measurements in the Internet to derive realistic data about the traffic that is injected into the OBS network. Specifically, we investigate the marginal distributions of burst size, burst interdeparture time, assembly delay and number of packets per burst as well as the burstiness of the burst traces. We demonstrate that the performance of an OBS core node using the real traces is pretty similar to the results obtained when the traffic arriving to the core node is assumed to be Poisson. In fact, usage of the Poisson as the process of burst arrival to the core node leads in all the investigated cases to an upper bound on the burst drop rate at that node. Copyright © 2009 John Wiley & Sons, Ltd. [source] Traffic flow continuum modeling by hypersingular boundary integral equationsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 1 2010Luis M. Romero Abstract The quantity of data necessary in order to study traffic in dense urban areas through a traffic network, and the large volume of information that is provided as a result, causes managerial difficulties for the said model. A study of this kind is expensive and complex, with many sources of error connected to each step carried out. A simplification like the continuous medium is a reasonable approximation and, for certain dimensions of the actual problem, may be an alternative to be kept in mind. The hypotheses of the continuous model introduce errors comparable to those associated with geometric inaccuracies in the transport network, with the grouping of hundreds of streets in one same type of link and therefore having the same functional characteristics, with the centralization of all journey departure points and destinations in discrete centroids and with the uncertainty produced by a huge origin/destination matrix that is quickly phased out, etc. In the course of this work, a new model for characterizing traffic in dense network cities as a continuous medium, the diffusion,advection model, is put forward. The model is approached by means of the boundary element method, which has the fundamental characteristic of only requiring the contour of the problem to be discretized, thereby reducing the complexity and need for information into one order versus other more widespread methods, such as finite differences and the finite element method. On the other hand, the boundary elements method tends to give a more complex mathematical formulation. In order to validate the proposed technique, three examples in their fullest form are resolved with a known analytic solution. Copyright © 2009 John Wiley & Sons, Ltd. [source] Trunking of TDM and narrowband services over IP NetworksINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 1 2003Dr James Aweya The recent interest in IP as the vehicle for transporting TDM and narrowband services stems from the possibility of using a common transport network for voice, video, and data, and the flexibility with which new services can be introduced. A key step in the evolution of networks towards a ,broadband' IP-based environment is the ,graceful' interworking of the IP networks with the existing networks and services, particularly with the circuit switched telephone network. A ,graceful' interworking approach is one whose complexity is minimal and preserves the user's perceived quality of service (QoS). To interwork with a circuit switched network whose services are pre-dominantly time-sensitive, the IP network must essentially behave as a transparent ,link' in the end-to-end connection. This paper presents an overview of the main technical problems to be addressed when trunking TDM and narrowband services over IP networks. Copyright © 2002 John Wiley & Sons, Ltd. [source] Hierarchical VP restoration management system for a reliable ATM backbone networkINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 4 2002Won-Kyu Hong This paper proposes a distributed ATM VP PVC restoration framework with the dynamic rerouting schemes in a hierarchical transport network. The rerouting algorithm aims to provide rapid ATM VP PVC restoration in the case of fault or performance degradation in terms of maximization of network resource utilization and satisfaction of the end user's QoS requirement. Copyright © 2002 John Wiley & Sons, Ltd. [source] Passenger route guidance system for multi-modal transit networksJOURNAL OF ADVANCED TRANSPORTATION, Issue 3 2005Hong K. Lo In many public transport oriented cities in the world, especially Asian cities, the public transport system has been developed extensively, to the extent that it has become increasingly difficult to navigate. Although inter-modal transfers are common and often necessary, a complete set of the routes across transport modes is generally not presented in a form that is accessible to travelers, as each operator would only publish its own routes. Moreover, the common nonlinear fare tables together with inter-modal fare discounts pose challenges to travelers in deciding their best routes. This study develops a multi-modal passenger route guidance system, called eFinder, to aid travelers with their combined mode-route choices. We discuss the architecture and features of this system in this study. This system forms a platform for disseminating public transit information and should complement further development and use of the public transport network by enabling travelers to make informed choices. [source] On QoS mechanism profiling in MPLS-TP transport networksBELL LABS TECHNICAL JOURNAL, Issue 4 2010Christian Addeo In the context of packet management in optical transport networks, quality of service (QoS) is playing an important role to achieve the right levels of bandwidth, latency, and general treatment for the different services carried over the network. The scope of this paper is to describe quality of service functionalities in the context of a packet transport network. This paper refers to the definition and implementation of the quality of service model in a packet transport network node, describing how this information is carried over a packet transport network. The Alcatel-Lucent 1850 Transport Service Switch (TSS) platform serves as our reference point for a packet transport node. We also include a description of classification, policing, marking, and, in particular, hierarchical scheduling and shaping. © 2010 Alcatel-Lucent. [source] Generalized MPLS-based distributed control architecture for automatically switched transport networksBELL LABS TECHNICAL JOURNAL, Issue 1 2001Yangguang Xu Current circuit-switched transport networks, such as plesiochronous digital hierarchy (PDH) and synchronous optical network/synchronous digital hierarchy (SONET/SDH), have traditionally used centralized network management for connection control. To facilitate the value-added capabilities of today's networks,such as the rapid provisioning of services, dynamic setup of bandwidth requests, and fast mesh-based restoration,distributed connection control using signaling protocols has quickly gained industry momentum. Efforts have been initiated in various standards bodies to define the automatically switched transport network (ASTN). Although many architectural choices are now available, this paper describes a distributed control plane architecture that can be applied to various circuit-switching technologies and different network applications. This architecture adopts the concept of a generalized version of multiprotocol label switching (MPLS), which extends and modifies MPLS and other protocols on the Internet to make them applicable to various transport networks and also facilitates optical data networking. Four major functional components are incorporated in this architecture: element-level resource discovery, state information dissemination, path selection, and path control modules. Using these concepts, the transport network can be viewed as a virtual nonblocking, reconfigurable backplane of different network clients. This view represents a radical departure from the traditional data networking view of transport networks as providing fixed pipes and will have a dramatic impact on future network interworking and end-to-end traffic engineering (TE). [source] The impact of an alien plant on a native plant,pollinator network: an experimental approachECOLOGY LETTERS, Issue 7 2007Martha E. Lopezaraiza, Mikel Abstract Studies of pairwise interactions have shown that an alien plant can affect the pollination of a native plant, this effect being mediated by shared pollinators. Here we use a manipulative field experiment, to investigate the impact of the alien plant Impatiens glandulifera on an entire community of coflowering native plants. Visitation and pollen transport networks were constructed to compare replicated I. glandulifera invaded and I. glandulifera removal plots. Invaded plots had significantly higher visitor species richness, visitor abundance and flower visitation. However, the pollen transport networks were dominated by alien pollen grains in the invaded plots and consequently higher visitation may not translate in facilitation for pollination. The more generalized insects were more likely to visit the alien plant, and Hymenoptera and Hemiptera were more likely to visit the alien than Coleoptera. Our data indicate that generalized native pollinators can provide a pathway of integration for alien plants into native visitation systems. [source] Infrastructure and Rural Development: US and EU Perspectives Infrastruktur und Entwicklung des ländlichen Raums: Perspektiven aus den USA und der EU Infrastructures et développement rural : Perspectives aux États-Unis et dans l'Union européenneEUROCHOICES, Issue 1 2008David Blandford Infrastructure and Rural Development: US and EU Perspectives Infrastructural development remains a cornerstone of rural development policy in both the United States and Europe. It is evident that rural development objectives differ, but similar policy measures are used. The economic rationale for infrastructure development centres on efficiency and creation of competitive advantage. Policy intervention is justified because of the added costs of infrastructure provision in remote, sparsely populated areas. Although this policy focus does not guarantee success, regions leading in economic development typically have better physical infrastructure. In the United States, policy must adapt to challenges posed by an ageing rural infrastructure and demographic change that will increase demands on social infrastructure such as housing and health facilities. There will be greater local responsibility for funding, and expanded use of public/private partnerships. In the European Union, the major challenge is in redirecting resources to new member states, where there is urgent need for both large new investments in transport networks and small investments to improve local access. Although two current options for funding these diverse needs focus on European policies only, investments in non-farm physical capital and public infrastructure cannot be sustained without active national policies to complement the European efforts, perhaps through co-financing requirements. Infrastructures et développement rural : Perspectives aux États-Unis et dans l'Union européenne Le développement des infrastructures demeure un pilier de la politique de développement rural aux États-Unis comme dans l'Union européenne. Les objectifs de développement rural diffèrent bien évidemment mais des mesures semblables sont employées. La justification économique du développement des infrastructures repose sur l'efficience et la création d'avantages concurrentiels. L'intervention publique est justifiée par les coûts supplémentaires des infrastructures dans les zones éloignées à population clairsemée. Bien que ce type de politique ne garantisse pas le succès, les régions en avance de développement économique ont en général de meilleures infrastructures physiques. Aux États-Unis, la politique soit s'adapter aux défis que posent le vieillissement des infrastructures rurales et l'évolution démographique qui va augmenter la demande d'infrastructures sociales telles que les services de santé et de logement. La responsabilité du financement local va augmenter et les partenariats public/privé vont se développer. Dans l'Union européenne, le principal défi est de réorienter les ressources vers les nouveaux pays membres qui ont un besoin urgent de nouveaux investissement d'ampleur dans les réseaux de transport et d'investissement de plus faible ampleur dans l'amélioration des accès locaux. Deux options actuelles de financement de ces divers besoins se concentrent sur les seules politiques européennes, mais les investissements dans le capital physique non agricole et dans les infrastructures publiques ne peuvent pas se poursuivre sans des politiques nationales actives complémentant les efforts fournis au niveau européen, peut-être à travers des mécanismes de co-financement. Infrastruktur und Entwicklung des ländlichen Raums: Perspektiven aus den USA und der EU Bei der Entwicklung der Infrastruktur handelt es sich nach wie vor sowohl in den USA als auch in Europa um einen Eckpfeiler in der Politik zur Entwicklung des ländlichen Raums. Es ist offensichtlich, dass sich die Ziele bei der Entwicklung des ländlichen Raums unterscheiden, die Politikmaßnahmen ähneln sich jedoch. Die wirtschaftliche Begründung für die Entwicklung der Infrastruktur zielt auf die Effizienz und das Schaffen von Wettbewerbsvorteilen ab. Politikeingriffe sind gerechtfertigt, da die Bereitstellung von Infrastruktur in entlegenen, dünn besiedelten Gebieten höhere Kosten verursacht. Obgleich dieser Schwerpunkt der Politik den Erfolg noch nicht garantiert, verfügen die wirtschaftlich am weitesten entwickelten Regionen typischerweise über eine bessere physische Infrastruktur. In den USA muss sich die Politik an die Herausforderungen anpassen, welche eine in die Jahre gekommene Infrastruktur im ländlichen Raum und der demografische Wandel mit sich bringen, und wodurch neue Anforderungen an die soziale Infrastruktur, wie z.B. Wohnungsbau und Gesundheitseinrichtungen, gestellt werden. Bei der Finanzierung werden die Kommunen stärker in die Verantwortung genommen, und öffentlich-private Partnerschaften werden an Bedeutung gewinnen. In der EU besteht die größte Herausforderung darin, Ressourcen zu den neuen Mitgliedstaaten umzuverteilen, wo sowohl neue Großinvestitionen in die Transportnetzwerke als auch kleinere Investitionen zur Verbesserung des lokalen Zugangs dringend benötigt werden. Obwohl sich die beiden im Moment vorhandenen Optionen zur Finanzierung dieser vielfältigen Bedürfnisse ausschließlich auf europäische Politikmaßnahmen konzentrieren, können die Investitionen in außerlandwirtschaftliches physisches Kapital und in die öffentliche Infrastruktur nicht ohne wirksame Politikmaßnahmen auf nationaler Ebene (z.B. die Pflicht zur Kofinanzierung) als Ergänzung zu den Bemühungen auf europäischer Ebene aufrecht erhalten werden. [source] Traffic analysis in optical burst switching networks: a trace-based case studyEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 7 2009Ahmad Rostami Optical burst switching (OBS) appears as a promising technology for building dynamic optical transport networks. The main advantage of OBS is that it allows for dynamic allocation of resources at sub-wavelength granularity. Nevertheless, the burst contention problem, which occurs frequently inside the network, has to be addressed before OBS can be really deployed as the next generation optical transport network. Recently a lot of attention is devoted to different approaches for resolving contentions in OBS networks. Although performance analysis of these approaches is strongly dependent on the traffic characteristics in the network, the majority of the studies is so far based on very hypothetical traffic assumptions. In this study we use traces of real measurements in the Internet to derive realistic data about the traffic that is injected into the OBS network. Specifically, we investigate the marginal distributions of burst size, burst interdeparture time, assembly delay and number of packets per burst as well as the burstiness of the burst traces. We demonstrate that the performance of an OBS core node using the real traces is pretty similar to the results obtained when the traffic arriving to the core node is assumed to be Poisson. In fact, usage of the Poisson as the process of burst arrival to the core node leads in all the investigated cases to an upper bound on the burst drop rate at that node. Copyright © 2009 John Wiley & Sons, Ltd. [source] IntServ6: an approach to support QoS over IPv6 wired and wireless networksEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 6 2008Jhon J. Padilla In this paper we propose a new approach for Quality of Service (QoS) support on Internet. This approach, named IntServ6, is based on the Integrated Services Architecture (ISA). It takes advantage of the IPv6 header flow label field to improve a set of the standard ISA properties such as reservations within tunnels, flows aggregation and interconnection with MPLS transport networks. IntServ6 can be used for QoS support in IPv6 wired and wireless networks. This paper describes the IntServ6 operation and performance evaluation over both environments. Evaluation results show that this approach has a better router performance with respect to the standard IntServ. Thus, IntServ6 reduces the mean packet delay and reduces the packet delay dependence with the mobility. Copyright © 2007 John Wiley & Sons, Ltd. [source] Radio resource management across multiple protocol layers in satellite networks: a tutorial overviewINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 5 2005Paolo Barsocchi Abstract Satellite transmissions have an important role in telephone communications, television broadcasting, computer communications, maritime navigation, and military command and control. Moreover, in many situations they may be the only possible communication set-up. Trends in telecommunications indicate that four major growth market/service areas are messaging and navigation services (wireless and satellite), mobility services (wireless and satellite), video delivery services (cable and satellite), and interactive multimedia services (fibre/cable, satellite). When using geostationary satellites (GEO), the long propagation delay may have great impact, given the end-to-end delay user's requirements of relevant applications; moreover, atmospheric conditions may seriously affect data transmission. Since satellite bandwidth is a relatively scarce resource compared to the terrestrial one (e.g. in optical transport networks), and the environment is harsher, resource management of the radio segment plays an important role in the system's efficiency and economy. The radio resource management (RMM) entity is responsible for the utilization of the air interface resources, and covers power control, handover, admission control, congestion control, bandwidth allocation, and packet scheduling. RRM functions are crucial for the best possible utilization of the capacity. RRM functions can be implemented in different ways, thus having an impact on the overall system efficiency. This tutorial aims to provide an overview of satellite transmission aspects at various OSI layers, with emphasis on the MAC layer; some cross-layer solutions for bandwidth allocation are also indicated. Far from being an exhaustive survey (mainly due to the extensive nature of the subject), it offers the readers an extensive bibliography, which could be used for further research on specific aspects. Copyright © 2005 John Wiley & Sons, Ltd. [source] Multi-level Environmentalism and the European Union: The Case of Trans-European Transport NetworksINTERNATIONAL JOURNAL OF URBAN AND REGIONAL RESEARCH, Issue 1 2006HEIN-ANTON VAN DER HEIJDEN In the European Union, trans-European transport networks (TENs) are a vital element in the constitution of one European space in order to enable the free movement of people and goods throughout the Union. Their construction, however, often causes environmental degradation. Opposition to EU politics is mostly voiced at the level of individual nation-states. As the case of TENs reveals, however, protest against European policy projects with environmental side effects can take the form of ,multi-level environmentalism', linking lobbying and ,conscientization' in Brussels with direct action at the national and local levels. Civil society theory, social movement theory and governance theory help ensure a theoretically informed answer to the question of how the resistance to TENs is organized and framed. By questioning dominant problem definitions and solution strategies, environmental movements and movement organizations, both in Brussels and in the individual nation-states, point to the possibility of looking at social and political reality from another, non-hegemonic point of view. In this way, they contribute to challenging the often biased technocratic, growth-oriented character of the European Union. [source] On QoS mechanism profiling in MPLS-TP transport networksBELL LABS TECHNICAL JOURNAL, Issue 4 2010Christian Addeo In the context of packet management in optical transport networks, quality of service (QoS) is playing an important role to achieve the right levels of bandwidth, latency, and general treatment for the different services carried over the network. The scope of this paper is to describe quality of service functionalities in the context of a packet transport network. This paper refers to the definition and implementation of the quality of service model in a packet transport network node, describing how this information is carried over a packet transport network. The Alcatel-Lucent 1850 Transport Service Switch (TSS) platform serves as our reference point for a packet transport node. We also include a description of classification, policing, marking, and, in particular, hierarchical scheduling and shaping. © 2010 Alcatel-Lucent. [source] Generalized MPLS-based distributed control architecture for automatically switched transport networksBELL LABS TECHNICAL JOURNAL, Issue 1 2001Yangguang Xu Current circuit-switched transport networks, such as plesiochronous digital hierarchy (PDH) and synchronous optical network/synchronous digital hierarchy (SONET/SDH), have traditionally used centralized network management for connection control. To facilitate the value-added capabilities of today's networks,such as the rapid provisioning of services, dynamic setup of bandwidth requests, and fast mesh-based restoration,distributed connection control using signaling protocols has quickly gained industry momentum. Efforts have been initiated in various standards bodies to define the automatically switched transport network (ASTN). Although many architectural choices are now available, this paper describes a distributed control plane architecture that can be applied to various circuit-switching technologies and different network applications. This architecture adopts the concept of a generalized version of multiprotocol label switching (MPLS), which extends and modifies MPLS and other protocols on the Internet to make them applicable to various transport networks and also facilitates optical data networking. Four major functional components are incorporated in this architecture: element-level resource discovery, state information dissemination, path selection, and path control modules. Using these concepts, the transport network can be viewed as a virtual nonblocking, reconfigurable backplane of different network clients. This view represents a radical departure from the traditional data networking view of transport networks as providing fixed pipes and will have a dramatic impact on future network interworking and end-to-end traffic engineering (TE). [source] | |||||||||||||