Science.gov

Sample records for public transport networks

  1. Public transport networks: empirical analysis and modeling

    NASA Astrophysics Data System (ADS)

    von Ferber, C.; Holovatch, T.; Holovatch, Yu.; Palchykov, V.

    2009-03-01

    Public transport networks of fourteen cities of so far unexplored network size are analyzed in standardized graph representations: the simple graph of the network map, the bipartite graph of routes and stations, and both one mode projections of the latter. Special attention is paid to the inter-relations and spatial embedding of transport routes. This systematic approach reveals rich behavior beyond that of the ubiquitous scale-free complex network. We find strong evidence for structures in PTNs that are counter-intuitive and need to be explained, among these a pronounced diversity in the expression of typical network characteristics within the present sample of cities, a surprising geometrical behavior with respect to the two-dimensional geographical embedding and an unexpected attraction between transport routes. A simple model based on these observations reproduces many of the identified PTN properties by growing networks of attractive self-avoiding walks.

  2. Network harness: bundles of routes in public transport networks

    NASA Astrophysics Data System (ADS)

    Berche, B.; von Ferber, C.; Holovatch, T.

    2009-12-01

    Public transport routes sharing the same grid of streets and tracks are often found to proceed in parallel along shorter or longer sequences of stations. Similar phenomena are observed in other networks built with space consuming links such as cables, vessels, pipes, neurons, etc. In the case of public transport networks (PTNs) this behavior may be easily worked out on the basis of sequences of stations serviced by each route. To quantify this behavior we use the recently introduced notion of network harness. It is described by the harness distribution P(r, s): the number of sequences of s consecutive stations that are serviced by r parallel routes. For certain PTNs that we have analyzed we observe that the harness distribution may be described by power laws. These power laws indicate a certain level of organization and planning which may be driven by the need to minimize the costs of infrastructure and secondly by the fact that points of interest tend to be clustered in certain locations of a city. This effect may be seen as a result of the strong interdependence of the evolutions of both the city and its PTN. To further investigate the significance of the empirical results we have studied one- and two-dimensional models of randomly placed routes modeled by different types of walks. While in one dimension an analytic treatment was successful, the two dimensional case was studied by simulations showing that the empirical results for real PTNs deviate significantly from those expected for randomly placed routes.

  3. Statistical analysis of 22 public transport networks in Poland.

    PubMed

    Sienkiewicz, Julian; Hołyst, Janusz A

    2005-10-01

    Public transport systems in 22 Polish cities have been analyzed. The sizes of these networks range from N = 152 to 2881. Depending on the assumed definition of network topology, the degree distribution can follow a power law or can be described by an exponential function. Distributions of path lengths in all considered networks are given by asymmetric, unimodal functions. Clustering, assortativity, and betweenness are studied. All considered networks exhibit small-world behavior and are hierarchically organized. A transition between dissortative small networks N approximately < or = 500 and assortative large networks N approximately > or = 500 is observed. PMID:16383488

  4. Statistical analysis of 22 public transport networks in Poland

    NASA Astrophysics Data System (ADS)

    Sienkiewicz, Julian; Hołyst, Janusz A.

    2005-10-01

    Public transport systems in 22 Polish cities have been analyzed. The sizes of these networks range from N=152 to 2881. Depending on the assumed definition of network topology, the degree distribution can follow a power law or can be described by an exponential function. Distributions of path lengths in all considered networks are given by asymmetric, unimodal functions. Clustering, assortativity, and betweenness are studied. All considered networks exhibit small-world behavior and are hierarchically organized. A transition between dissortative small networks N≲500 and assortative large networks N≳500 is observed.

  5. The multilayer temporal network of public transport in Great Britain

    PubMed Central

    Gallotti, Riccardo; Barthelemy, Marc

    2015-01-01

    Despite the widespread availability of information concerning public transport coming from different sources, it is extremely hard to have a complete picture, in particular at a national scale. Here, we integrate timetable data obtained from the United Kingdom open-data program together with timetables of domestic flights, and obtain a comprehensive snapshot of the temporal characteristics of the whole UK public transport system for a week in October 2010. In order to focus on multi-modal aspects of the system, we use a coarse graining procedure and define explicitly the coupling between different transport modes such as connections at airports, ferry docks, rail, metro, coach and bus stations. The resulting weighted, directed, temporal and multilayer network is provided in simple, commonly used formats, ensuring easy access and the possibility of a straightforward use of old or specifically developed methods on this new and extensive dataset. PMID:25977806

  6. Provision of Ubiquitous Tourist Information in Public Transport Networks

    PubMed Central

    García, Carmelo R.; Pérez, Ricardo; Alayón, Francisco; Quesada-Arencibia, Alexis; Padrón, Gabino

    2012-01-01

    This paper outlines an information system for tourists using collective public transport based on mobile devices with limited computation and wireless connection capacities. In this system, the mobile device collaborates with the vehicle infrastructure in order to provide the user with multimedia (visual and audio) information about his/her trip. The information delivered, adapted to the user preferences, is synchronized with the passage of vehicles through points of interest along the route, for example: bus stops, tourist sights, public service centres, etc.

  7. Weighted complex network analysis of travel routes on the Singapore public transportation system

    NASA Astrophysics Data System (ADS)

    Soh, Harold; Lim, Sonja; Zhang, Tianyou; Fu, Xiuju; Lee, Gary Kee Khoon; Hung, Terence Gih Guang; Di, Pan; Prakasam, Silvester; Wong, Limsoon

    2010-12-01

    The structure and properties of public transportation networks have great implications for urban planning, public policies and infectious disease control. We contribute a complex weighted network analysis of travel routes on the Singapore rail and bus transportation systems. We study the two networks using both topological and dynamical analyses. Our results provide additional evidence that a dynamical study adds to the information gained by traditional topological analysis, providing a richer view of complex weighted networks. For example, while initial topological measures showed that the rail network is almost fully connected, dynamical measures highlighted hub nodes that experience disproportionately large traffic. The dynamical assortativity of the bus networks also differed from its topological counterpart. In addition, inspection of the weighted eigenvector centralities highlighted a significant difference in traffic flows for both networks during weekdays and weekends, suggesting the importance of adding a temporal perspective missing from many previous studies.

  8. User-based representation of time-resolved multimodal public transportation networks.

    PubMed

    Alessandretti, Laura; Karsai, Márton; Gauvin, Laetitia

    2016-07-01

    Multimodal transportation systems, with several coexisting services like bus, tram and metro, can be represented as time-resolved multilayer networks where the different transportation modes connecting the same set of nodes are associated with distinct network layers. Their quantitative description became possible recently due to openly accessible datasets describing the geo-localized transportation dynamics of large urban areas. Advancements call for novel analytics, which combines earlier established methods and exploits the inherent complexity of the data. Here, we provide a novel user-based representation of public transportation systems, which combines representations, accounting for the presence of multiple lines and reducing the effect of spatial embeddedness, while considering the total travel time, its variability across the schedule, and taking into account the number of transfers necessary. After the adjustment of earlier techniques to the novel representation framework, we analyse the public transportation systems of several French municipal areas and identify hidden patterns of privileged connections. Furthermore, we study their efficiency as compared to the commuting flow. The proposed representation could help to enhance resilience of local transportation systems to provide better design policies for future developments. PMID:27493773

  9. User-based representation of time-resolved multimodal public transportation networks

    PubMed Central

    Alessandretti, Laura; Gauvin, Laetitia

    2016-01-01

    Multimodal transportation systems, with several coexisting services like bus, tram and metro, can be represented as time-resolved multilayer networks where the different transportation modes connecting the same set of nodes are associated with distinct network layers. Their quantitative description became possible recently due to openly accessible datasets describing the geo-localized transportation dynamics of large urban areas. Advancements call for novel analytics, which combines earlier established methods and exploits the inherent complexity of the data. Here, we provide a novel user-based representation of public transportation systems, which combines representations, accounting for the presence of multiple lines and reducing the effect of spatial embeddedness, while considering the total travel time, its variability across the schedule, and taking into account the number of transfers necessary. After the adjustment of earlier techniques to the novel representation framework, we analyse the public transportation systems of several French municipal areas and identify hidden patterns of privileged connections. Furthermore, we study their efficiency as compared to the commuting flow. The proposed representation could help to enhance resilience of local transportation systems to provide better design policies for future developments. PMID:27493773

  10. A method of examining the structure and topological properties of public-transport networks

    NASA Astrophysics Data System (ADS)

    Dimitrov, Stavri Dimitri; Ceder, Avishai (Avi)

    2016-06-01

    This work presents a new method of examining the structure of public-transport networks (PTNs) and analyzes their topological properties through a combination of computer programming, statistical data and large-network analyses. In order to automate the extraction, processing and exporting of data, a software program was developed allowing to extract the needed data from General Transit Feed Specification, thus overcoming difficulties occurring in accessing and collecting data. The proposed method was applied to a real-life PTN in Auckland, New Zealand, with the purpose of examining whether it showed characteristics of scale-free networks and exhibited features of "small-world" networks. As a result, new regression equations were derived analytically describing observed, strong, non-linear relationships among the probabilities of randomly chosen stops in the PTN to be serviced by a given number of routes. The established dependence is best fitted by an exponential rather than a power-law function, showing that the PTN examined is neither random nor scale-free, but a mixture of the two. This finding explains the presence of hubs that are not typical of exponential networks and simultaneously not highly connected to the other nodes as is the case with scale-free networks. On the other hand, the observed values of the topological properties of the network show that although it is highly clustered, owing to its representation as a directed graph, it differs slightly from "small-world" networks, which are characterized by strong clustering and a short average path length.

  11. Animal transportation networks.

    PubMed

    Perna, Andrea; Latty, Tanya

    2014-11-01

    Many group-living animals construct transportation networks of trails, galleries and burrows by modifying the environment to facilitate faster, safer or more efficient movement. Animal transportation networks can have direct influences on the fitness of individuals, whereas the shape and structure of transportation networks can influence community dynamics by facilitating contacts between different individuals and species. In this review, we discuss three key areas in the study of animal transportation networks: the topological properties of networks, network morphogenesis and growth, and the behaviour of network users. We present a brief primer on elements of network theory, and then discuss the different ways in which animal groups deal with the fundamental trade-off between the competing network properties of travel efficiency, robustness and infrastructure cost. We consider how the behaviour of network users can impact network efficiency, and call for studies that integrate both network topology and user behaviour. We finish with a prospectus for future research. PMID:25165598

  12. Animal transportation networks

    PubMed Central

    Perna, Andrea; Latty, Tanya

    2014-01-01

    Many group-living animals construct transportation networks of trails, galleries and burrows by modifying the environment to facilitate faster, safer or more efficient movement. Animal transportation networks can have direct influences on the fitness of individuals, whereas the shape and structure of transportation networks can influence community dynamics by facilitating contacts between different individuals and species. In this review, we discuss three key areas in the study of animal transportation networks: the topological properties of networks, network morphogenesis and growth, and the behaviour of network users. We present a brief primer on elements of network theory, and then discuss the different ways in which animal groups deal with the fundamental trade-off between the competing network properties of travel efficiency, robustness and infrastructure cost. We consider how the behaviour of network users can impact network efficiency, and call for studies that integrate both network topology and user behaviour. We finish with a prospectus for future research. PMID:25165598

  13. Vgi Based Urban Public Transport

    NASA Astrophysics Data System (ADS)

    Teymurian, F.; Alesheikh, A. A.; Alimohammadi, A.; Sadeghi-Niaraki, A.

    2013-09-01

    Recent advances in information technology have made geographic information system (GIS) a powerful and affordable tool for planning and decision making in various fields such as the public transportation. These technologies such as the social network (e.g. face-book, twitter), new technologies such as ubiquitous, mobile, Web 2.0, geo tagging and RFID can help to create better shapes and forms of the communication and geo-collaboration for public. By using these, user-generated content and spatial information can be easily and quickly produced and shared in a dynamic, interactive, multimedia and distributed environment. The concept of volunteered geographic information (VGI) has been introduced by the transaction from consultation to content interaction. VGI describes any type of content that has a geographic element and has been voluntarily collected. In other words, ordinary users; without a professional training, can participate in generating and using the spatial information. As a result, the gaps between the producers and users of GIS and spatial information, has been considerably reduced. Public transportation is one of the most important elements of the transportation system. Rapid growth of the cities has resulted in high increase of demand for the public transportation which created new challenges. Improvement of the desirability of public transportation can increase its efficiency, reduction of the environmental pollution (such as air and noise pollution), traffic problems, and fuel consumption. Hence, development of an urban public transportation system which is responsive to citizen's need and motivates them to use public transportation system is one of the most important objectives and issues that urban planners and designers are concerned about. One solution to achieve this, goal is to develop public transportation system by assistance from the system users. According to approach, users are considered as the valuable resources, because people who are

  14. Packet transport network in metro

    NASA Astrophysics Data System (ADS)

    Huang, Feng; Yi, Xiaobo; Zhang, Hanzheng; Gong, Ping

    2008-11-01

    IP packet based services such as high speed internet, IP voice and IP video will be widely deployed in telecom network, which make transport network evolution to packet transport network. Characteristics of transport network and requirements of packet transport network are analyzed, T-MPLS/MPLS-TP based PTN technology is given and it will be used in metro (access, aggregation and core) network.

  15. Transportation Network Topologies

    NASA Technical Reports Server (NTRS)

    Holmes, Bruce J.; Scott, John M.

    2004-01-01

    A discomforting reality has materialized on the transportation scene: our existing air and ground infrastructures will not scale to meet our nation's 21st century demands and expectations for mobility, commerce, safety, and security. The consequence of inaction is diminished quality of life and economic opportunity in the 21st century. Clearly, new thinking is required for transportation that can scale to meet to the realities of a networked, knowledge-based economy in which the value of time is a new coin of the realm. This paper proposes a framework, or topology, for thinking about the problem of scalability of the system of networks that comprise the aviation system. This framework highlights the role of integrated communication-navigation-surveillance systems in enabling scalability of future air transportation networks. Scalability, in this vein, is a goal of the recently formed Joint Planning and Development Office for the Next Generation Air Transportation System. New foundations for 21PstP thinking about air transportation are underpinned by several technological developments in the traditional aircraft disciplines as well as in communication, navigation, surveillance and information systems. Complexity science and modern network theory give rise to one of the technological developments of importance. Scale-free (i.e., scalable) networks represent a promising concept space for modeling airspace system architectures, and for assessing network performance in terms of scalability, efficiency, robustness, resilience, and other metrics. The paper offers an air transportation system topology as framework for transportation system innovation. Successful outcomes of innovation in air transportation could lay the foundations for new paradigms for aircraft and their operating capabilities, air transportation system architectures, and airspace architectures and procedural concepts. The topology proposed considers air transportation as a system of networks, within

  16. Transportation Network Topologies

    NASA Technical Reports Server (NTRS)

    Holmes, Bruce J.; Scott, John

    2004-01-01

    A discomforting reality has materialized on the transportation scene: our existing air and ground infrastructures will not scale to meet our nation's 21st century demands and expectations for mobility, commerce, safety, and security. The consequence of inaction is diminished quality of life and economic opportunity in the 21st century. Clearly, new thinking is required for transportation that can scale to meet to the realities of a networked, knowledge-based economy in which the value of time is a new coin of the realm. This paper proposes a framework, or topology, for thinking about the problem of scalability of the system of networks that comprise the aviation system. This framework highlights the role of integrated communication-navigation-surveillance systems in enabling scalability of future air transportation networks. Scalability, in this vein, is a goal of the recently formed Joint Planning and Development Office for the Next Generation Air Transportation System. New foundations for 21st thinking about air transportation are underpinned by several technological developments in the traditional aircraft disciplines as well as in communication, navigation, surveillance and information systems. Complexity science and modern network theory give rise to one of the technological developments of importance. Scale-free (i.e., scalable) networks represent a promising concept space for modeling airspace system architectures, and for assessing network performance in terms of scalability, efficiency, robustness, resilience, and other metrics. The paper offers an air transportation system topology as framework for transportation system innovation. Successful outcomes of innovation in air transportation could lay the foundations for new paradigms for aircraft and their operating capabilities, air transportation system architectures, and airspace architectures and procedural concepts. The topology proposed considers air transportation as a system of networks, within which

  17. Toward Optimal Transport Networks

    NASA Technical Reports Server (NTRS)

    Alexandrov, Natalia; Kincaid, Rex K.; Vargo, Erik P.

    2008-01-01

    Strictly evolutionary approaches to improving the air transport system a highly complex network of interacting systems no longer suffice in the face of demand that is projected to double or triple in the near future. Thus evolutionary approaches should be augmented with active design methods. The ability to actively design, optimize and control a system presupposes the existence of predictive modeling and reasonably well-defined functional dependences between the controllable variables of the system and objective and constraint functions for optimization. Following recent advances in the studies of the effects of network topology structure on dynamics, we investigate the performance of dynamic processes on transport networks as a function of the first nontrivial eigenvalue of the network's Laplacian, which, in turn, is a function of the network s connectivity and modularity. The last two characteristics can be controlled and tuned via optimization. We consider design optimization problem formulations. We have developed a flexible simulation of network topology coupled with flows on the network for use as a platform for computational experiments.

  18. Transportation Network Topologies

    NASA Technical Reports Server (NTRS)

    Alexandrov, Natalia (Editor)

    2004-01-01

    The existing U.S. hub-and-spoke air transportation system is reaching saturation. Major aspects of the current system, such as capacity, safety, mobility, customer satisfaction, security, communications, and ecological effects, require improvements. The changing dynamics - increased presence of general aviation, unmanned autonomous vehicles, military aircraft in civil airspace as part of homeland defense - contributes to growing complexity of airspace. The system has proven remarkably resistant to change. NASA Langley Research Center and the National Institute of Aerospace conducted a workshop on Transportation Network Topologies on 9-10 December 2003 in Williamsburg, Virginia. The workshop aimed to examine the feasibility of traditional methods for complex system analysis and design as well as potential novel alternatives in application to transportation systems, identify state-of-the-art models and methods, conduct gap analysis, and thus to lay a foundation for establishing a focused research program in complex systems applied to air transportation.

  19. Urban public transportation research, 1990

    SciTech Connect

    Lee, D.A.; Barnum, D.T.; Gleason, J.M.; Mundle, S.R.; Kraus, J.E.

    1990-01-01

    The 30 papers in the Record provide a good cross section of current research in public transportation. They have been grouped into six topics--management, finance, planning, bus operations, rail transit operations, and new technology.

  20. Scaling in Transportation Networks

    PubMed Central

    Louf, Rémi; Roth, Camille; Barthelemy, Marc

    2014-01-01

    Subway systems span most large cities, and railway networks most countries in the world. These networks are fundamental in the development of countries and their cities, and it is therefore crucial to understand their formation and evolution. However, if the topological properties of these networks are fairly well understood, how they relate to population and socio-economical properties remains an open question. We propose here a general coarse-grained approach, based on a cost-benefit analysis that accounts for the scaling properties of the main quantities characterizing these systems (the number of stations, the total length, and the ridership) with the substrate's population, area and wealth. More precisely, we show that the length, number of stations and ridership of subways and rail networks can be estimated knowing the area, population and wealth of the underlying region. These predictions are in good agreement with data gathered for about subway systems and more than railway networks in the world. We also show that train networks and subway systems can be described within the same framework, but with a fundamental difference: while the interstation distance seems to be constant and determined by the typical walking distance for subways, the interstation distance for railways scales with the number of stations. PMID:25029528

  1. Kansas Public Television Network (KPTN).

    ERIC Educational Resources Information Center

    Lemen, Jack A.

    The plans of the Kansas Public Television Board (KPTB) for development of the Kansas Television Network are detailed for the period extending from FY 1979 to FY 1983; the proposed system is designed to serve the needs of the communities by extending existing capabilities and resources, sharing common resources, and enriching the total system.…

  2. Transportation Networks for Emergency Evacuations

    SciTech Connect

    Franzese, Oscar; Liu, Cheng

    2008-01-01

    Evacuation modeling systems (EMS) have been developed to facilitate the planning, analysis, and deployment of emergency evacuation of populations at risk. For any EMS, data such as road network maps, traffic control characteristics, and population distribution play critical roles in delineating emergency zones, estimating population at risk, and determining evacuation routes. There are situations in which it is possible to plan in advance for an emergency evacuation including, for example, an explosion at a chemical processing facility or a radiological accident at a nuclear plant. In these cases, if an accident or a terrorist attack were to happen, then the best evacuation plan for the prevailing network and weather conditions would be deployed. In other instances -for example, the derailment of a train transporting hazardous materials-, there may not be any previously developed plan to be implemented and decisions must be made ad-hoc on if and how to identify and proceed with the best course of action to minimize losses. Although both cases require as a starting point the development of a transportation network model of the area at risk, which must include road capacity and topology, in the latter the available time to generate this network is extremely limited. This time constraint precludes the use of any traditional data gathering methodology and the network generation process has to rely on the use of GIS and stochastic modeling techniques. The generation of these transportation networks in real time is the focus of this entry.

  3. Insight to the express transport network

    NASA Astrophysics Data System (ADS)

    Yang, Hua; Nie, Yuchao; Zhang, Hongbin; Di, Zengru; Fan, Ying

    2009-09-01

    The express delivery industry is developing rapidly in recent years and has attracted attention in many fields. Express shipment service requires that parcels be delivered in a limited time with a low operation cost, which requests a high level and efficient express transport network (ETN). The ETN is constructed based on the public transport networks, especially the airline network. It is similar to the airline network in some aspects, while it has its own feature. With the complex network theory, the topological properties of the ETN are analyzed deeply. We find that the ETN has the small-world property, with disassortative mixing behavior and rich club phenomenon. It also shows difference from the airline network in some features, such as edge density and average shortest path. Analysis on the corresponding distance-weighted network shows that the distance distribution displays a truncated power-law behavior. At last, an evolving model, which takes both geographical constraint and preference attachment into account, is proposed. The model shows similar properties with the empirical results.

  4. IAU Public Astronomical Organisations Network

    NASA Astrophysics Data System (ADS)

    Canas, Lina; Cheung, Sze Leung

    2015-08-01

    The Office for Astronomy Outreach has devoted intensive means to create and support a global network of public astronomical organisations around the world. Focused on bringing established and newly formed amateur astronomy organizations together, providing communications channels and platforms for disseminating news to the global community and the sharing of best practices and resources among these associations around the world. In establishing the importance that these organizations have for the dissemination of activities globally and acting as key participants in IAU various campaigns social media has played a key role in keeping this network engaged and connected. Here we discuss the implementation process of maintaining this extensive network, the processing and gathering of information and the interactions between local active members at a national and international level.

  5. Systematic Development of Intelligent Systems for Public Road Transport.

    PubMed

    García, Carmelo R; Quesada-Arencibia, Alexis; Cristóbal, Teresa; Padrón, Gabino; Alayón, Francisco

    2016-01-01

    This paper presents an architecture model for the development of intelligent systems for public passenger transport by road. The main objective of our proposal is to provide a framework for the systematic development and deployment of telematics systems to improve various aspects of this type of transport, such as efficiency, accessibility and safety. The architecture model presented herein is based on international standards on intelligent transport system architectures, ubiquitous computing and service-oriented architecture for distributed systems. To illustrate the utility of the model, we also present a use case of a monitoring system for stops on a public passenger road transport network. PMID:27438836

  6. Systematic Development of Intelligent Systems for Public Road Transport

    PubMed Central

    García, Carmelo R.; Quesada-Arencibia, Alexis; Cristóbal, Teresa; Padrón, Gabino; Alayón, Francisco

    2016-01-01

    This paper presents an architecture model for the development of intelligent systems for public passenger transport by road. The main objective of our proposal is to provide a framework for the systematic development and deployment of telematics systems to improve various aspects of this type of transport, such as efficiency, accessibility and safety. The architecture model presented herein is based on international standards on intelligent transport system architectures, ubiquitous computing and service-oriented architecture for distributed systems. To illustrate the utility of the model, we also present a use case of a monitoring system for stops on a public passenger road transport network. PMID:27438836

  7. Rural Public Transportation: An Instructional Module.

    ERIC Educational Resources Information Center

    Hayden, Linda

    A concept-based introduction to rural public transportation is provided in this instructional module for undergraduate and graduate transportation-related courses for disciplines such as engineering, business, sociology, and technology. Rural public transportation involves systems in rural and small urban areas with populations under 50,000…

  8. Structural and robustness properties of smart-city transportation networks

    NASA Astrophysics Data System (ADS)

    Zhang, Zhen-Gang; Ding, Zhuo; Fan, Jing-Fang; Meng, Jun; Ding, Yi-Min; Ye, Fang-Fu; Chen, Xiao-Song

    2015-09-01

    The concept of smart city gives an excellent resolution to construct and develop modern cities, and also demands infrastructure construction. How to build a safe, stable, and highly efficient public transportation system becomes an important topic in the process of city construction. In this work, we study the structural and robustness properties of transportation networks and their sub-networks. We introduce a complementary network model to study the relevance and complementarity between bus network and subway network. Our numerical results show that the mutual supplement of networks can improve the network robustness. This conclusion provides a theoretical basis for the construction of public traffic networks, and it also supports reasonable operation of managing smart cities. Project supported by the Major Projects of the China National Social Science Fund (Grant No. 11 & ZD154).

  9. Optimal Concentrations in Transport Networks

    NASA Astrophysics Data System (ADS)

    Jensen, Kaare; Savage, Jessica; Kim, Wonjung; Bush, John; Holbrook, N. Michele

    2013-03-01

    Biological and man-made systems rely on effective transport networks for distribution of material and energy. Mass flow in these networks is determined by the flow rate and the concentration of material. While the most concentrated solution offers the greatest potential for mass flow, impedance grows with concentration and thus makes it the most difficult to transport. The concentration at which mass flow is optimal depends on specific physical and physiological properties of the system. We derive a simple model which is able to predict optimal concentrations observed in blood flows, sugar transport in plants, and nectar feeding animals. Our model predicts that the viscosity at the optimal concentration μopt =2nμ0 is an integer power of two times the viscosity of the pure carrier medium μ0. We show how the observed powers 1 <= n <= 6 agree well with theory and discuss how n depends on biological constraints imposed on the transport process. The model provides a universal framework for studying flows impeded by concentration and provides hints of how to optimize engineered flow systems, such as congestion in traffic flows.

  10. Public Transportation Pricing: An Instructional Module.

    ERIC Educational Resources Information Center

    McWha, Charley

    A concept-based introduction to public transportation pricing is presented in this instructional module for undergraduate and graduate transportation-related courses for disciplines such as engineering, business administration, and technology. After an introductory section on transportation pricing planning and the history of transportation system…

  11. Public Health Disease Surveillance Networks.

    PubMed

    Morse, Stephen S

    2014-02-01

    Zoonotic infections are important sources of human disease; most known emerging infections are zoonotic (e.g., HIV, Ebola virus, severe acute respiratory syndrome, Nipah virus, and enteropathogenic Escherichia coli) and originated as natural infections of other species that acquired opportunities to come in contact with humans. There are also serious infectious diseases classically considered zoonotic, such as influenza, rabies, bubonic plague, brucellosis, and leptospirosis. More recently, it has been recognized that wildlife constitutes a particularly important source of novel zoonoses. With all this microbial movement, surveillance is considered the first line of public health defense. The zoonotic origin of many human and livestock infections argues strongly for the synergistic value of a One Health approach, which provides the capability to identify pathogens crossing into new species and could provide earlier warning of potential epidemics. This article discusses public health surveillance and major recent surveillance initiatives and reviews progress toward implementing a One Health surveillance framework. Networks discussed include global intergovernmental organizations and recent combined efforts of these organizations; Web-based nongovernmental systems (e.g., ProMED, the Program for Monitoring Emerging Diseases); and networks of bilateral or multilateral government programs (e.g., the CDC's Global Disease Detection [GDD] platform; the U.S. Department of Defense's Global Emerging Infections Surveillance and Response System [GEIS]; regional and subregional networks; and the U.S. Agency for International Development's Emerging Pandemic Threats [EPT] program and its surveillance component, PREDICT). Syndromic surveillance also has potential to complement existing systems. New technologies are enabling revolutionary capabilities for global surveillance, but in addition to serious technical needs, both sustainability and data-sharing mechanisms remain

  12. Influence of public transport in black carbon

    NASA Astrophysics Data System (ADS)

    Vasquez, Y.; Oyola, P.; Gramsch, E. V.; Moreno, F.; Rubio, M.

    2013-05-01

    . Yañez, a decrease in Alameda and no change in Departamental. The small increases in BC in some streets, and the decrease observed in an avenue dominated by public transportation, suggest that the reason of the increase in BC concentration is related to the increment in the total number of vehicles (diesel and non diesel). The lower number of buses or improved bus technology did not have an effect on BC concentrations. The three streets that increased or maintained the BC concentration had higher number of vehicles in 2007. Alameda Avenue showed a decrease in BC concentration that had to do with a lower total number of vehicles as well as improved bus technology in year 2007 than year 2005. The emissions, related exclusively to public transportation, seem to have diminished after the Transantiago implementation, considering the outcome in the observed BC in Alameda, mainly dominated by the public transport network. These results are an indication that in order to decrease pollution near a street is not enough to reduce the number of buses or improve its quality, but to reduce the total number of vehicles.

  13. Charge transport network dynamics in molecular aggregates.

    PubMed

    Jackson, Nicholas E; Chen, Lin X; Ratner, Mark A

    2016-08-01

    Due to the nonperiodic nature of charge transport in disordered systems, generating insight into static charge transport networks, as well as analyzing the network dynamics, can be challenging. Here, we apply time-dependent network analysis to scrutinize the charge transport networks of two representative molecular semiconductors: a rigid n-type molecule, perylenediimide, and a flexible p-type molecule, [Formula: see text] Simulations reveal the relevant timescale for local transfer integral decorrelation to be [Formula: see text]100 fs, which is shown to be faster than that of a crystalline morphology of the same molecule. Using a simple graph metric, global network changes are observed over timescales competitive with charge carrier lifetimes. These insights demonstrate that static charge transport networks are qualitatively inadequate, whereas average networks often overestimate network connectivity. Finally, a simple methodology for tracking dynamic charge transport properties is proposed. PMID:27439871

  14. An Investigation of Synchrony in Transport Networks

    NASA Technical Reports Server (NTRS)

    Kincaid, Rex K.; Alexandrov, Natalia M.; Holroyd, Michael J.

    2007-01-01

    The cumulative degree distributions of transport networks, such as air transportation networks and respiratory neuronal networks, follow power laws. The significance of power laws with respect to other network performance measures, such as throughput and synchronization, remains an open question. Evolving methods for the analysis and design of air transportation networks must address network performance in the face of increasing demands and the need to contain and control local network disturbances, such as congestion. Toward this end, we investigate functional relationships that govern the performance of transport networks; for example, the links between the first nontrivial eigenvalue of a network's Laplacian matrix - a quantitative measure of network synchronizability - and other global network parameters. In particular, among networks with a fixed degree distribution and fixed network assortativity (a measure of a network's preference to attach nodes based on a similarity or difference), those with the small eigenvalue are shown to be poor synchronizers, to have much longer shortest paths and to have greater clustering in comparison to those with large. A simulation of a respiratory network adds data to our investigation. This study is a beginning step in developing metrics and design variables for the analysis and active design of air transport networks.

  15. Structure and formation of ant transportation networks

    PubMed Central

    Latty, Tanya; Ramsch, Kai; Ito, Kentaro; Nakagaki, Toshiyuki; Sumpter, David J. T.; Middendorf, Martin; Beekman, Madeleine

    2011-01-01

    Many biological systems use extensive networks for the transport of resources and information. Ants are no exception. How do biological systems achieve efficient transportation networks in the absence of centralized control and without global knowledge of the environment? Here, we address this question by studying the formation and properties of inter-nest transportation networks in the Argentine ant (Linepithema humile). We find that the formation of inter-nest networks depends on the number of ants involved in the construction process. When the number of ants is sufficient and networks do form, they tend to have short total length but a low level of robustness. These networks are topologically similar to either minimum spanning trees or Steiner networks. The process of network formation involves an initial construction of multiple links followed by a pruning process that reduces the number of trails. Our study thus illuminates the conditions under and the process by which minimal biological transport networks can be constructed. PMID:21288958

  16. Information transport in multiplex networks

    NASA Astrophysics Data System (ADS)

    Pu, Cunlai; Li, Siyuan; Yang, Xianxia; Yang, Jian; Wang, Kai

    2016-04-01

    In this paper, we study information transport in multiplex networks comprised of two coupled subnetworks. The upper subnetwork, called the logical layer, employs the shortest paths protocol to determine the logical paths for packets transmission, while the lower subnetwork acts as the physical layer, in which packets are delivered by the biased random walk mechanism characterized with a parameter α. Through simulation, we obtain the optimal α corresponding to the maximum network lifetime and the maximum number of the arrival packets. Assortative coupling is better than random coupling and disassortative coupling, since it achieves better transmission performance. Generally, the more homogeneous the lower subnetwork is, the better the transmission performance, which is the opposite for the upper subnetwork. Finally, we propose an attack centrality for nodes based on the topological information of both subnetworks, and investigate the transmission performance under targeted attacks. Our work aids in understanding the spread and robustness issues of multiplex networks and provides some clues about the design of more efficient and robust routing architectures in communication systems.

  17. Cytoskeletal Network Morphology Regulates Intracellular Transport Dynamics.

    PubMed

    Ando, David; Korabel, Nickolay; Huang, Kerwyn Casey; Gopinathan, Ajay

    2015-10-20

    Intracellular transport is essential for maintaining proper cellular function in most eukaryotic cells, with perturbations in active transport resulting in several types of disease. Efficient delivery of critical cargos to specific locations is accomplished through a combination of passive diffusion and active transport by molecular motors that ballistically move along a network of cytoskeletal filaments. Although motor-based transport is known to be necessary to overcome cytoplasmic crowding and the limited range of diffusion within reasonable timescales, the topological features of the cytoskeletal network that regulate transport efficiency and robustness have not been established. Using a continuum diffusion model, we observed that the time required for cellular transport was minimized when the network was localized near the nucleus. In simulations that explicitly incorporated network spatial architectures, total filament mass was the primary driver of network transit times. However, filament traps that redirect cargo back to the nucleus caused large variations in network transport. Filament polarity was more important than filament orientation in reducing average transit times, and transport properties were optimized in networks with intermediate motor on and off rates. Our results provide important insights into the functional constraints on intracellular transport under which cells have evolved cytoskeletal structures, and have potential applications for enhancing reactions in biomimetic systems through rational transport network design. PMID:26488648

  18. Optimizing Nutrient Uptake in Biological Transport Networks

    NASA Astrophysics Data System (ADS)

    Ronellenfitsch, Henrik; Katifori, Eleni

    2013-03-01

    Many biological systems employ complex networks of vascular tubes to facilitate transport of solute nutrients, examples include the vascular system of plants (phloem), some fungi, and the slime-mold Physarum. It is believed that such networks are optimized through evolution for carrying out their designated task. We propose a set of hydrodynamic governing equations for solute transport in a complex network, and obtain the optimal network architecture for various classes of optimizing functionals. We finally discuss the topological properties and statistical mechanics of the resulting complex networks, and examine correspondence of the obtained networks to those found in actual biological systems.

  19. Biological solutions to transport network design.

    PubMed

    Bebber, Daniel P; Hynes, Juliet; Darrah, Peter R; Boddy, Lynne; Fricker, Mark D

    2007-09-22

    Transport networks are vital components of multicellular organisms, distributing nutrients and removing waste products. Animal and plant transport systems are branching trees whose architecture is linked to universal scaling laws in these organisms. In contrast, many fungi form reticulated mycelia via the branching and fusion of thread-like hyphae that continuously adapt to the environment. Fungal networks have evolved to explore and exploit a patchy environment, rather than ramify through a three-dimensional organism. However, there has been no explicit analysis of the network structures formed, their dynamic behaviour nor how either impact on their ecological function. Using the woodland saprotroph Phanerochaete velutina, we show that fungal networks can display both high transport capacity and robustness to damage. These properties are enhanced as the network grows, while the relative cost of building the network decreases. Thus, mycelia achieve the seemingly competing goals of efficient transport and robustness, with decreasing relative investment, by selective reinforcement and recycling of transport pathways. Fungal networks demonstrate that indeterminate, decentralized systems can yield highly adaptive networks. Understanding how these relatively simple organisms have found effective transport networks through a process of natural selection may inform the design of man-made networks. PMID:17623638

  20. Improving Network Transport Efficiency by Edge Rewiring

    NASA Astrophysics Data System (ADS)

    Jiang, Zhong-Yuan; Liang, Man-Gui; Guo, Dong-Chao

    2013-03-01

    Considering the heterogeneous structure of scale-free networks causing low traffic capacity of network, we propose to improve the network transport efficiency by rewiring a fraction of edges for the network. In this paper, six edge rewiring strategies are discussed and extensive simulations on Barabási-Albert (BA) scale-free networks confirm the effectiveness of these strategies. From another perspective, rewiring edges for scale-free networks directly reuse the removed edges under some edge-removal strategies [Z. Liu, M. B. Hu, R. Jiang, W. X. Wang and Q. S. Wu, Phys. Rev. E76 (2007) 037101; G. Q. Zhang, D. Wang and G. J. Li, Phys. Rev. E76 (2007) 017101], and can significantly enhance the traffic capacity of the network at the expense of increasing a little average path length. After the edge rewiring process, the network structure becomes significantly homogeneous. This work is helpful for network design and network performance optimization.

  1. Optimal transport on supply-demand networks

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Han; Wang, Bing-Hong; Zhao, Li-Chao; Zhou, Changsong; Zhou, Tao

    2010-06-01

    In the literature, transport networks are usually treated as homogeneous networks, that is, every node has the same function, simultaneously providing and requiring resources. However, some real networks, such as power grids and supply chain networks, show a far different scenario in which nodes are classified into two categories: supply nodes provide some kinds of services, while demand nodes require them. In this paper, we propose a general transport model for these supply-demand networks, associated with a criterion to quantify their transport capacities. In a supply-demand network with heterogeneous degree distribution, its transport capacity strongly depends on the locations of supply nodes. We therefore design a simulated annealing algorithm to find the near optimal configuration of supply nodes, which remarkably enhances the transport capacity compared with a random configuration and outperforms the degree target algorithm, the betweenness target algorithm, and the greedy method. This work provides a start point for systematically analyzing and optimizing transport dynamics on supply-demand networks.

  2. A Survey of Neural Network Publications.

    ERIC Educational Resources Information Center

    Vijayaraman, Bindiganavale S.; Osyk, Barbara

    This paper is a survey of publications on artificial neural networks published in business journals for the period ending July 1996. Its purpose is to identify and analyze trends in neural network research during that period. This paper shows which topics have been heavily researched, when these topics were researched, and how that research has…

  3. Caring for Older People. Public transport.

    PubMed Central

    Roper, T. A.; Mulley, G. P.

    1996-01-01

    Most older people are mobile and able to use public transport without any problems. Those who are hard of hearing or have poor vision and those with mobility problems need not be deterred from using public transport. Though the design and provision of suitable buses, taxis, and trains is not always optimum, many now have imaginative features to help older passengers. Travel by air and sea needs extra planning for disabled elderly people, but helpful advice is available and much can be done to enable even the most disabled traveller to make long journeys confidently and in comfort. Images p415-a Fig 1 Fig 2 Fig 3 PMID:8761236

  4. Public Transportation and Pulmonary Tuberculosis, Lima, Peru

    PubMed Central

    Sánchez-Pérez, Héctor J.; Sánchez, Inma; Bedoya, Alfredo; Martín, Miguel

    2007-01-01

    The association between public transportation for commuting and pulmonary tuberculosis (TB) was analyzed in workers in Lima, Peru. Traveling in minibuses was a risk factor for pulmonary TB. Preventive measures need to be taken by health services to prevent spread of this disease. PMID:18257992

  5. A computational study of routing algorithms for realistic transportation networks

    SciTech Connect

    Jacob, R.; Marathe, M.V.; Nagel, K.

    1998-12-01

    The authors carry out an experimental analysis of a number of shortest path (routing) algorithms investigated in the context of the TRANSIMS (Transportation Analysis and Simulation System) project. The main focus of the paper is to study how various heuristic and exact solutions, associated data structures affected the computational performance of the software developed especially for realistic transportation networks. For this purpose the authors have used Dallas Fort-Worth road network with very high degree of resolution. The following general results are obtained: (1) they discuss and experimentally analyze various one-one shortest path algorithms, which include classical exact algorithms studied in the literature as well as heuristic solutions that are designed to take into account the geometric structure of the input instances; (2) they describe a number of extensions to the basic shortest path algorithm. These extensions were primarily motivated by practical problems arising in TRANSIMS and ITS (Intelligent Transportation Systems) related technologies. Extensions discussed include--(i) time dependent networks, (ii) multi-modal networks, (iii) networks with public transportation and associated schedules. Computational results are provided to empirically compare the efficiency of various algorithms. The studies indicate that a modified Dijkstra`s algorithm is computationally fast and an excellent candidate for use in various transportation planning applications as well as ITS related technologies.

  6. Advanced data services over optical transport networks

    NASA Astrophysics Data System (ADS)

    Ong, Lyndon; Razdan, Rajender; Wang, Yalin

    2005-11-01

    Work on optical network control plane protocols has enabled faster and more efficient provisioning and management of carrier core optical networks, thereby reducing operational costs and capital expenditure. Many potential data applications for such capabilities, however, require Ethernet as the physical interface into the network, rather than SONET/SDH or OTN (Optical Transport Network) interfaces. Support of such services over an optical network becomes a multi-layer networking problem, wherein the client layer is packet based (e.g., Ethernet) and the server layer is optical (SONET/SDH or OTN). This paper discusses the enhancements that have been created in SONET/SDH and OTN networks (e.g., GFP, VCAT, LCAS) for the efficient transport of Ethernet and other data networking protocols, and the related extensions to control plane protocols that are necessary to allow for the support of multi-layer networking. Different control-plane models are being pursued in standards bodies such as ITU-T and IETF, and prototyping is being carried out and tested in the OIF. These various approaches are discussed in detail here, with focus placed on the prototyping work that has been done in the OIF, especially for the OIF 2005 Interoperability Demonstration.

  7. 78 FR 61251 - The National Public Transportation Safety Plan, the Public Transportation Agency Safety Plan, and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-03

    ...The Federal Transit Administration (FTA) is issuing this consolidated advance notice of proposed rulemaking (ANPRM) to request public comments on a wide range of topics pertaining to the new Public Transportation Safety Program (National Safety Program) and the requirements of the new transit asset management provisions (National TAM System) authorized by the Moving Ahead for Progress in the......

  8. Community core detection in transportation networks.

    PubMed

    De Leo, Vincenzo; Santoboni, Giovanni; Cerina, Federica; Mureddu, Mario; Secchi, Luca; Chessa, Alessandro

    2013-10-01

    This work analyzes methods for the identification and the stability under perturbation of a territorial community structure with specific reference to transportation networks. We considered networks of commuters for a city and an insular region. In both cases, we have studied the distribution of commuters' trips (i.e., home-to-work trips and vice versa). The identification and stability of the communities' cores are linked to the land-use distribution within the zone system, and therefore their proper definition may be useful to transport planners. PMID:24229228

  9. Community core detection in transportation networks

    NASA Astrophysics Data System (ADS)

    De Leo, Vincenzo; Santoboni, Giovanni; Cerina, Federica; Mureddu, Mario; Secchi, Luca; Chessa, Alessandro

    2013-10-01

    This work analyzes methods for the identification and the stability under perturbation of a territorial community structure with specific reference to transportation networks. We considered networks of commuters for a city and an insular region. In both cases, we have studied the distribution of commuters’ trips (i.e., home-to-work trips and vice versa). The identification and stability of the communities’ cores are linked to the land-use distribution within the zone system, and therefore their proper definition may be useful to transport planners.

  10. Integrated management of optical transport networks

    NASA Astrophysics Data System (ADS)

    Wang, Yun; Zeng, QingJi; Yang, Xudong

    2000-12-01

    Optical transport networks (OTN) technology is expected to play a vital role in the next-generation transport networks. In this paper, the technology of OTN and management of OTN is discussed. Combined with TMN, SNMP and CORBA, integrated management of OTN is investigated. Q-adapter is proposed to integrate TMN and SNMP together, and a direct CORBA/SNMP interface is given to implement the integration of CORBA and SNMP. Finally, several issues concerning integrated management of OTN are also discussed, such as integrate routing of OTN in IP layer and in optical layer, multilayer protection of OTN and OAM technology of OTN.

  11. 47 CFR 90.19 - Nationwide Public Safety Broadband Network.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Nationwide Public Safety Broadband Network. 90... Safety Broadband Network. Pursuant to the Middle Class Tax Relief and Job Creation Act of 2012, Public... First Responder Network Authority to deploy a nationwide public safety broadband network as...

  12. 47 CFR 90.19 - Nationwide Public Safety Broadband Network.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Nationwide Public Safety Broadband Network. 90... Safety Broadband Network. Pursuant to the Middle Class Tax Relief and Job Creation Act of 2012, Public... First Responder Network Authority to deploy a nationwide public safety broadband network as...

  13. Understanding and managing disaster evacuation on a transportation network.

    PubMed

    Lambert, James H; Parlak, Ayse I; Zhou, Qian; Miller, John S; Fontaine, Michael D; Guterbock, Thomas M; Clements, Janet L; Thekdi, Shital A

    2013-01-01

    Uncertain population behaviors in a regional emergency could potentially harm the performance of the region's transportation system and subsequent evacuation effort. The integration of behavioral survey data with travel demand modeling enables an assessment of transportation system performance and the identification of operational and public health countermeasures. This paper analyzes transportation system demand and system performance for emergency management in three disaster scenarios. A two-step methodology first estimates the number of trips evacuating the region, thereby capturing behavioral aspects in a scientifically defensible manner based on survey results, and second, assigns these trips to a regional highway network, using geographic information systems software, thereby making the methodology transferable to other locations. Performance measures are generated for each scenario including maps of volume-to-capacity ratios, geographic contours of evacuation time from the center of the region, and link-specific metrics such as weighted average speed and traffic volume. The methods are demonstrated on a 600 segment transportation network in Washington, DC (USA) and are applied to three scenarios involving attacks from radiological dispersion devices (e.g., dirty bombs). The results suggests that: (1) a single detonation would degrade transportation system performance two to three times more than that which occurs during a typical weekday afternoon peak hour, (2) volume on several critical arterials within the network would exceed capacity in the represented scenarios, and (3) resulting travel times to reach intended destinations imply that un-aided evacuation is impractical. These results assist decisions made by two categories of emergency responders: (1) transportation managers who provide traveler information and who make operational adjustments to improve the network (e.g., signal retiming) and (2) public health officials who maintain shelters, food and

  14. Identifying Network Public Opinion Leaders Based on Markov Logic Networks

    PubMed Central

    Zhang, Weizhe; Li, Xiaoqiang; He, Hui; Wang, Xing

    2014-01-01

    Public opinion emergencies have important effect on social activities. Recognition of special communities like opinion leaders can contribute to a comprehensive understanding of the development trend of public opinion. In this paper, a network opinion leader recognition method based on relational data was put forward, and an opinion leader recognition system integrating public opinion data acquisition module, data characteristic selection, and fusion module as well as opinion leader discovery module based on Markov Logic Networks was designed. The designed opinion leader recognition system not only can overcome the incomplete data acquisition and isolated task of traditional methods, but also can recognize opinion leaders comprehensively with considerations to multiple problems by using the relational model. Experimental results demonstrated that, compared with the traditional methods, the proposed method can provide a more accurate opinion leader recognition and has good noise immunity. PMID:24977188

  15. The association between access to public transportation and self-reported active commuting.

    PubMed

    Djurhuus, Sune; Hansen, Henning S; Aadahl, Mette; Glümer, Charlotte

    2014-12-01

    Active commuting provides routine-based regular physical activity which can reduce the risk of chronic diseases. Using public transportation involves some walking or cycling to a transit stop, transfers and a walk to the end location and users of public transportation have been found to accumulate more moderate physical activity than non-users. Understanding how public transportation characteristics are associated with active transportation is thus important from a public health perspective. This study examines the associations between objective measures of access to public transportation and self-reported active commuting. Self-reported time spent either walking or cycling commuting each day and the distance to workplace were obtained for adults aged 16 to 65 in the Danish National Health Survey 2010 (n = 28,928). Access to public transportation measures were computed by combining GIS-based road network distances from home address to public transit stops an integrating their service level. Multilevel logistic regression was used to examine the association between access to public transportation measures and active commuting. Distance to bus stop, density of bus stops, and number of transport modes were all positively associated with being an active commuter and with meeting recommendations of physical activity. No significant association was found between bus services at the nearest stop and active commuting. The results highlight the importance of including detailed measurements of access to public transit in order to identify the characteristics that facilitate the use of public transportation and active commuting. PMID:25489998

  16. The Association between Access to Public Transportation and Self-Reported Active Commuting

    PubMed Central

    Djurhuus, Sune; Hansen, Henning S.; Aadahl, Mette; Glümer, Charlotte

    2014-01-01

    Active commuting provides routine-based regular physical activity which can reduce the risk of chronic diseases. Using public transportation involves some walking or cycling to a transit stop, transfers and a walk to the end location and users of public transportation have been found to accumulate more moderate physical activity than non-users. Understanding how public transportation characteristics are associated with active transportation is thus important from a public health perspective. This study examines the associations between objective measures of access to public transportation and self-reported active commuting. Self-reported time spent either walking or cycling commuting each day and the distance to workplace were obtained for adults aged 16 to 65 in the Danish National Health Survey 2010 (n = 28,928). Access to public transportation measures were computed by combining GIS-based road network distances from home address to public transit stops an integrating their service level. Multilevel logistic regression was used to examine the association between access to public transportation measures and active commuting. Distance to bus stop, density of bus stops, and number of transport modes were all positively associated with being an active commuter and with meeting recommendations of physical activity. No significant association was found between bus services at the nearest stop and active commuting. The results highlight the importance of including detailed measurements of access to public transit in order to identify the characteristics that facilitate the use of public transportation and active commuting. PMID:25489998

  17. Particle Swarm Transport in Fracture Networks

    NASA Astrophysics Data System (ADS)

    Pyrak-Nolte, L. J.; Mackin, T.; Boomsma, E.

    2012-12-01

    Colloidal particles of many types occur in fractures in the subsurface as a result of both natural and industrial processes (e.g., environmental influences, synthetic nano- & micro-particles from consumer products, chemical and mechanical erosion of geologic material, proppants used in gas and oil extraction, etc.). The degree of localization and speed of transport of such particles depends on the transport mechanisms, the chemical and physical properties of the particles and the surrounding rock, and the flow path geometry through the fracture. In this study, we investigated the transport of particle swarms through artificial fracture networks. A synthetic fracture network was created using an Objet Eden 350V 3D printer to build a network of fractures. Each fracture in the network had a rectangular cross-sectional area with a constant depth of 7 mm but with widths that ranged from 2 mm to 11 mm. The overall dimensions of the network were 132 mm by 166 mm. The fracture network had 7 ports that were used either as the inlet or outlet for fluid flow through the sample or for introducing a particle swarm. Water flow rates through the fracture were controlled with a syringe pump, and ranged from zero flow to 6 ml/min. Swarms were composed of a dilute suspension (2% by mass) of 3 μm fluorescent polystyrene beads in water. Swarms with volumes of 5, 10, 20, 30 and 60 μl were used and delivered into the network using a second syringe pump. The swarm behavior was imaged using an optical fluorescent imaging system illuminated by green (525 nm) LED arrays and captured by a CCD camera. For fracture networks with quiescent fluids, particle swarms fell under gravity and remained localized within the network. Large swarms (30-60 μl) were observed to bifurcate at shallower depths resulting in a broader dispersal of the particles than for smaller swarm volumes. For all swarm volumes studied, particle swarms tended to bifurcate at the intersection between fractures. These

  18. Complex Network Theory Applied to the Growth of Kuala Lumpur's Public Urban Rail Transit Network.

    PubMed

    Ding, Rui; Ujang, Norsidah; Hamid, Hussain Bin; Wu, Jianjun

    2015-01-01

    Recently, the number of studies involving complex network applications in transportation has increased steadily as scholars from various fields analyze traffic networks. Nonetheless, research on rail network growth is relatively rare. This research examines the evolution of the Public Urban Rail Transit Networks of Kuala Lumpur (PURTNoKL) based on complex network theory and covers both the topological structure of the rail system and future trends in network growth. In addition, network performance when facing different attack strategies is also assessed. Three topological network characteristics are considered: connections, clustering and centrality. In PURTNoKL, we found that the total number of nodes and edges exhibit a linear relationship and that the average degree stays within the interval [2.0488, 2.6774] with heavy-tailed distributions. The evolutionary process shows that the cumulative probability distribution (CPD) of degree and the average shortest path length show good fit with exponential distribution and normal distribution, respectively. Moreover, PURTNoKL exhibits clear cluster characteristics; most of the nodes have a 2-core value, and the CPDs of the centrality's closeness and betweenness follow a normal distribution function and an exponential distribution, respectively. Finally, we discuss four different types of network growth styles and the line extension process, which reveal that the rail network's growth is likely based on the nodes with the biggest lengths of the shortest path and that network protection should emphasize those nodes with the largest degrees and the highest betweenness values. This research may enhance the networkability of the rail system and better shape the future growth of public rail networks. PMID:26448645

  19. Public transportation assistant for the cognitively impaired.

    PubMed

    Riehle, Timothy H; Anderson, Shane M; Lichter, Patrick A; Brown, Allen W; Hedin, Daniel S

    2011-01-01

    This project developed and evaluated the utility of a mobility assistant cognitive prosthetic that leverages the computing power and GPS location determination capabilities of smart phones to provide location-sensitive mobility assistance. New relatively inexpensive smart phones offer powerful computing and location sensing capabilities. A prototype cognitive prosthetic was developed to assist users in their use of transportation systems. User Interface design included remote caregiver programming features, and automated SMS status generation. Location specific memory cues are triggered by comparing current GPS coordinate location with expected route coordinates obtained from stored route databases based on the GTFS feeds from transit systems. Additional development focused on developing algorithms to identify potential user errors, such as wrong-bus. These reminders and instructions will allow cognitively disabled persons to utilize public transportation systems with greater confidence leading to greater mobility and independence. PMID:22256094

  20. 76 FR 82031 - Commercial Space Transportation Advisory Committee; Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-29

    ... Federal Aviation Administration Commercial Space Transportation Advisory Committee; Public Teleconference AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of Commercial Space Transportation... teleconference of the Commercial Space Transportation Advisory Committee (COMSTAC) Risk Management Working...

  1. 78 FR 14401 - Commercial Space Transportation Advisory Committee; Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-05

    ... Federal Aviation Administration Commercial Space Transportation Advisory Committee; Public Teleconference AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of Commercial Space Transportation... Working Group of the Commercial Space Transportation Advisory Committee (COMSTAC). DATES:...

  2. 76 FR 78329 - Commercial Space Transportation Advisory Committee; Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-16

    ... TRANSPORTATION Federal Aviation Administration Commercial Space Transportation Advisory Committee; Public Teleconference AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of Commercial Space... Commercial Space Transportation Advisory Committee (COMSTAC). The teleconference will take place on...

  3. 77 FR 35102 - Commercial Space Transportation Advisory Committee; Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-12

    ... Federal Aviation Administration Commercial Space Transportation Advisory Committee; Public Teleconference AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of Commercial Space Transportation... Working Group (OWG) of the Commercial Space Transportation Advisory Committee (COMSTAC)....

  4. 78 FR 53496 - Commercial Space Transportation Advisory Committee; Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-29

    ... Federal Aviation Administration Commercial Space Transportation Advisory Committee; Public Teleconference AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of Commercial Space Transportation... Space Transportation Advisory Committee (COMSTAC). DATES: The teleconference will take place on...

  5. Global Transport Networks and Infectious Disease Spread

    PubMed Central

    Tatem, A.J.; Rogers, D.J.; Hay, S.I.

    2011-01-01

    Air, sea and land transport networks continue to expand in reach, speed of travel and volume of passengers and goods carried. Pathogens and their vectors can now move further, faster and in greater numbers than ever before. Three important consequences of global transport network expansion are infectious disease pandemics, vector invasion events and vector-borne pathogen importation. This review briefly examines some of the important historical examples of these disease and vector movements, such as the global influenza pandemics, the devastating Anopheles gambiae invasion of Brazil and the recent increases in imported Plasmodium falciparum malaria cases. We then outline potential approaches for future studies of disease movement, focussing on vector invasion and vector-borne disease importation. Such approaches allow us to explore the potential implications of international air travel, shipping routes and other methods of transport on global pathogen and vector traffic. PMID:16647974

  6. Maximizing algebraic connectivity in air transportation networks

    NASA Astrophysics Data System (ADS)

    Wei, Peng

    In air transportation networks the robustness of a network regarding node and link failures is a key factor for its design. An experiment based on the real air transportation network is performed to show that the algebraic connectivity is a good measure for network robustness. Three optimization problems of algebraic connectivity maximization are then formulated in order to find the most robust network design under different constraints. The algebraic connectivity maximization problem with flight routes addition or deletion is first formulated. Three methods to optimize and analyze the network algebraic connectivity are proposed. The Modified Greedy Perturbation Algorithm (MGP) provides a sub-optimal solution in a fast iterative manner. The Weighted Tabu Search (WTS) is designed to offer a near optimal solution with longer running time. The relaxed semi-definite programming (SDP) is used to set a performance upper bound and three rounding techniques are discussed to find the feasible solution. The simulation results present the trade-off among the three methods. The case study on two air transportation networks of Virgin America and Southwest Airlines show that the developed methods can be applied in real world large scale networks. The algebraic connectivity maximization problem is extended by adding the leg number constraint, which considers the traveler's tolerance for the total connecting stops. The Binary Semi-Definite Programming (BSDP) with cutting plane method provides the optimal solution. The tabu search and 2-opt search heuristics can find the optimal solution in small scale networks and the near optimal solution in large scale networks. The third algebraic connectivity maximization problem with operating cost constraint is formulated. When the total operating cost budget is given, the number of the edges to be added is not fixed. Each edge weight needs to be calculated instead of being pre-determined. It is illustrated that the edge addition and the

  7. High fuel price: Will Indonesian shift to public transportation?

    NASA Astrophysics Data System (ADS)

    Sopha, Bertha Maya; Pamungkas, Adhiguna Ramadhani

    2016-06-01

    Public transportation has been declining over years, while on the other hand, private vehicles are dramatically increasing. The share of public transportation was 38.3% in 2002 and slowly decreasing to 12.9% in 2010. Cheap fuel price has been alleged to be the main cause for the increased private vehicles. The declining trend of public transportation needs further investigation whether higher fuel price indeed influences the choice of transportation mode. The present study therefore aims at exploring the preference of using public transportation compared to motorcycle and private car for various fuel price and identifying barriers toward public transportation. A survey was conducted in 2013 to capture the preference of each transportation mode given different fuel price. A questionnaire which was designed according to the structure of Analytical Hierarchy Process (AHP) was distributed using random sampling in ten cities in Sumatra and Java islands, Indonesia. Results indicate that the increased fuel price would not lead to significant increase of public transportation users. Motorcycle seems continuously being the dominating transportation mode in the future. On the other hand, issues resulted from limited public transportation capacity such as long travel time, security and safety issues, limited route, poor schedule appear to be the most barriers of using public transportation. It is implied that in order to promote public transportation, interventions should be introduced simultaneously at both supply (i.e., increasing public transportation capacity) and demand (i.e., high fuel price) sides. Limitations of the study are also discussed.

  8. 28 CFR 36.310 - Transportation provided by public accommodations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 28 Judicial Administration 1 2011-07-01 2011-07-01 false Transportation provided by public... BASIS OF DISABILITY BY PUBLIC ACCOMMODATIONS AND IN COMMERCIAL FACILITIES Specific Requirements § 36.310 Transportation provided by public accommodations. (a) General. (1) A public accommodation that...

  9. 28 CFR 36.310 - Transportation provided by public accommodations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 1 2014-07-01 2014-07-01 false Transportation provided by public... BASIS OF DISABILITY BY PUBLIC ACCOMMODATIONS AND IN COMMERCIAL FACILITIES Specific Requirements § 36.310 Transportation provided by public accommodations. (a) General. (1) A public accommodation that...

  10. 28 CFR 36.310 - Transportation provided by public accommodations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Transportation provided by public... BASIS OF DISABILITY BY PUBLIC ACCOMMODATIONS AND IN COMMERCIAL FACILITIES Specific Requirements § 36.310 Transportation provided by public accommodations. (a) General. (1) A public accommodation that...

  11. 28 CFR 36.310 - Transportation provided by public accommodations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 1 2013-07-01 2013-07-01 false Transportation provided by public... BASIS OF DISABILITY BY PUBLIC ACCOMMODATIONS AND IN COMMERCIAL FACILITIES Specific Requirements § 36.310 Transportation provided by public accommodations. (a) General. (1) A public accommodation that...

  12. 28 CFR 36.310 - Transportation provided by public accommodations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 1 2012-07-01 2012-07-01 false Transportation provided by public... BASIS OF DISABILITY BY PUBLIC ACCOMMODATIONS AND IN COMMERCIAL FACILITIES Specific Requirements § 36.310 Transportation provided by public accommodations. (a) General. (1) A public accommodation that...

  13. Weighted multiplex network of air transportation

    NASA Astrophysics Data System (ADS)

    Varga, Imre

    2016-06-01

    In several real networks large heterogeneity of links is present either in intensity or in the nature of relationships. Therefore, recent studies in network science indicate that more detailed topological information are available if weighted or multi-layer aspect is applied. In the age of globalization air transportation is a representative example of huge complex infrastructure systems, which has been analyzed from different points of view. In this paper a novel approach is applied to study the airport network as a weighted multiplex taking into account the fact that the rules and fashion of domestic and international flights differ. Restricting study to only topological features and their correlations in the system (disregarding traffic) one can see reasons why simple network approximation is not adequate.

  14. Characterization of attacks on public telephone networks

    NASA Astrophysics Data System (ADS)

    Lorenz, Gary V.; Manes, Gavin W.; Hale, John C.; Marks, Donald; Davis, Kenneth; Shenoi, Sujeet

    2001-02-01

    The U.S. Public Telephone Network (PTN) is a massively connected distributed information systems, much like the Internet. PTN signaling, transmission and operations functions must be protected from physical and cyber attacks to ensure the reliable delivery of telecommunications services. The increasing convergence of PTNs with wireless communications systems, computer networks and the Internet itself poses serious threats to our nation's telecommunications infrastructure. Legacy technologies and advanced services encumber well-known and as of yet undiscovered vulnerabilities that render them susceptible to cyber attacks. This paper presents a taxonomy of cyber attacks on PTNs in converged environments that synthesizes exploits in computer and communications network domains. The taxonomy provides an opportunity for the systematic exploration of mitigative and preventive strategies, as well as for the identification and classification of emerging threats.

  15. Optimal transport exponent in spatially embedded networks

    NASA Astrophysics Data System (ADS)

    Li, G.; Reis, S. D. S.; Moreira, A. A.; Havlin, S.; Stanley, H. E.; Andrade, J. S., Jr.

    2013-04-01

    The imposition of a cost constraint for constructing the optimal navigation structure surely represents a crucial ingredient in the design and development of any realistic navigation network. Previous works have focused on optimal transport in small-world networks built from two-dimensional lattices by adding long-range connections with Manhattan length rij taken from the distribution Pij˜rij-α, where α is a variable exponent. It has been shown that, by introducing a cost constraint on the total length of the additional links, regardless of the strategy used by the traveler (independent of whether it is based on local or global knowledge of the network structure), the best transportation condition is obtained with an exponent α=d+1, where d is the dimension of the underlying lattice. Here we present further support, through a high-performance real-time algorithm, on the validity of this conjecture in three-dimensional regular as well as in two-dimensional critical percolation clusters. Our results clearly indicate that cost constraint in the navigation problem provides a proper theoretical framework to justify the evolving topologies of real complex network structures, as recently demonstrated for the networks of the US airports and the human brain activity.

  16. Population-weighted efficiency in transportation networks.

    PubMed

    Dong, Lei; Li, Ruiqi; Zhang, Jiang; Di, Zengru

    2016-01-01

    Transportation efficiency is critical for the operation of cities and is attracting great attention worldwide. Improving the transportation efficiency can not only decrease energy consumption, reduce carbon emissions, but also accelerate people's interactions, which will become more and more important for sustainable urban living. Generally, traffic conditions in less-developed countries are not so good due to the undeveloped economy and road networks, while this issue is rarely studied before, because traditional survey data in these areas are scarce. Nowadays, with the development of ubiquitous mobile phone data, we can explore the transportation efficiency in a new way. In this paper, based on users' call detailed records (CDRs), we propose an indicator named population-weighted efficiency (PWE) to quantitatively measure the efficiency of the transportation networks. PWE can provide insights into transportation infrastructure development, according to which we identify dozens of inefficient routes at both the intra- and inter-city levels, which are verified by several ongoing construction projects in Senegal. In addition, we compare PWE with excess commuting indices, and the fitting result of PWE is better than excess commuting index, which also proves the validity of our method. PMID:27230706

  17. Population-weighted efficiency in transportation networks

    PubMed Central

    Dong, Lei; Li, Ruiqi; Zhang, Jiang; Di, Zengru

    2016-01-01

    Transportation efficiency is critical for the operation of cities and is attracting great attention worldwide. Improving the transportation efficiency can not only decrease energy consumption, reduce carbon emissions, but also accelerate people’s interactions, which will become more and more important for sustainable urban living. Generally, traffic conditions in less-developed countries are not so good due to the undeveloped economy and road networks, while this issue is rarely studied before, because traditional survey data in these areas are scarce. Nowadays, with the development of ubiquitous mobile phone data, we can explore the transportation efficiency in a new way. In this paper, based on users’ call detailed records (CDRs), we propose an indicator named population-weighted efficiency (PWE) to quantitatively measure the efficiency of the transportation networks. PWE can provide insights into transportation infrastructure development, according to which we identify dozens of inefficient routes at both the intra- and inter-city levels, which are verified by several ongoing construction projects in Senegal. In addition, we compare PWE with excess commuting indices, and the fitting result of PWE is better than excess commuting index, which also proves the validity of our method. PMID:27230706

  18. Population-weighted efficiency in transportation networks

    NASA Astrophysics Data System (ADS)

    Dong, Lei; Li, Ruiqi; Zhang, Jiang; di, Zengru

    2016-05-01

    Transportation efficiency is critical for the operation of cities and is attracting great attention worldwide. Improving the transportation efficiency can not only decrease energy consumption, reduce carbon emissions, but also accelerate people’s interactions, which will become more and more important for sustainable urban living. Generally, traffic conditions in less-developed countries are not so good due to the undeveloped economy and road networks, while this issue is rarely studied before, because traditional survey data in these areas are scarce. Nowadays, with the development of ubiquitous mobile phone data, we can explore the transportation efficiency in a new way. In this paper, based on users’ call detailed records (CDRs), we propose an indicator named population-weighted efficiency (PWE) to quantitatively measure the efficiency of the transportation networks. PWE can provide insights into transportation infrastructure development, according to which we identify dozens of inefficient routes at both the intra- and inter-city levels, which are verified by several ongoing construction projects in Senegal. In addition, we compare PWE with excess commuting indices, and the fitting result of PWE is better than excess commuting index, which also proves the validity of our method.

  19. Review of Public Safety in Viewpoint of Complex Networks

    NASA Astrophysics Data System (ADS)

    Chengcheng, Gai; Wenguo, Weng; Hongyong, Yuan

    2010-05-01

    In this paper, a brief review of public safety in viewpoint of complex networks is presented. Public safety incidents are divided into four categories: natural disasters, industry accidents, public health and social security, in which the complex network approaches and theories are need. We review how the complex network methods was developed and used in the studies of the three kinds of public safety incidents. The typical public safety incidents studied by the complex network methods in this paper are introduced, including the natural disaster chains, blackouts on electric power grids and epidemic spreading. Finally, we look ahead to the application prospects of the complex network theory on public safety.

  20. Mobile Network Data for Public Health: Opportunities and Challenges

    PubMed Central

    Oliver, Nuria; Matic, Aleksandar; Frias-Martinez, Enrique

    2015-01-01

    The ubiquity of mobile phones worldwide is generating an unprecedented amount of human behavioral data both at an individual and aggregated levels. The study of this data as a rich source of information about human behavior emerged almost a decade ago. Since then, it has grown into a fertile area of research named computational social sciences with a wide variety of applications in different fields such as social networks, urban and transport planning, economic development, emergency relief, and, recently, public health. In this paper, we briefly describe the state of the art on using mobile phone data for public health, and present the opportunities and challenges that this kind of data presents for public health. PMID:26301211

  1. Adaptation and optimization of biological transport networks.

    PubMed

    Hu, Dan; Cai, David

    2013-09-27

    It has been hypothesized that topological structures of biological transport networks are consequences of energy optimization. Motivated by experimental observation, we propose that adaptation dynamics may underlie this optimization. In contrast to the global nature of optimization, our adaptation dynamics responds only to local information and can naturally incorporate fluctuations in flow distributions. The adaptation dynamics minimizes the global energy consumption to produce optimal networks, which may possess hierarchical loop structures in the presence of strong fluctuations in flow distribution. We further show that there may exist a new phase transition as there is a critical open probability of sinks, above which there are only trees for network structures whereas below which loops begin to emerge. PMID:24116821

  2. Planning air transport network in Appalachia

    NASA Technical Reports Server (NTRS)

    Carter, E. C.; Morlok, E. K.

    1975-01-01

    Main issues to be considered in designing an air transport system are discussed, and a model for the selection of an optimal air network for a region is presented. It was desired to have the ability to consider a dense network of nodes and air routes and variations in schedules on routes, which in combination would represent virtually all conceivable alternatives. Linear and integer programming were chosen as the most promising analysis methodologies. Integer programming was found to be intractable, while linear programming provided efficient solutions. The model was applied to studying the feasibility of a STOL network in West Virginia. Based on allowable paths, an examination of intercity demands, and established growth points, desired levels of service expressed as minimum flights were determined for certain city pairs.

  3. Structural Properties of the Brazilian Air Transportation Network.

    PubMed

    Couto, Guilherme S; da Silva, Ana Paula Couto; Ruiz, Linnyer B; Benevenuto, Fabrício

    2015-09-01

    The air transportation network in a country has a great impact on the local, national and global economy. In this paper, we analyze the air transportation network in Brazil with complex network features to better understand its characteristics. In our analysis, we built networks composed either by national or by international flights. We also consider the network when both types of flights are put together. Interesting conclusions emerge from our analysis. For instance, Viracopos Airport (Campinas City) is the most central and connected airport on the national flights network. Any operational problem in this airport separates the Brazilian national network into six distinct subnetworks. Moreover, the Brazilian air transportation network exhibits small world characteristics and national connections network follows a power law distribution. Therefore, our analysis sheds light on the current Brazilian air transportation infrastructure, bringing a novel understanding that may help face the recent fast growth in the usage of the Brazilian transport network. PMID:26312421

  4. A game theory model of urban public traffic networks

    NASA Astrophysics Data System (ADS)

    Su, B. B.; Chang, H.; Chen, Y.-Z.; He, D. R.

    2007-06-01

    We have studied urban public traffic networks from the viewpoint of complex networks and game theory. Firstly, we have empirically investigated an urban public traffic network in Beijing in 2003, and obtained its statistical properties. Then a simplified game theory model is proposed for simulating the evolution of the traffic network. The basic idea is that three network manipulators, passengers, an urban public traffic company, and a government traffic management agency, play games in a network evolution process. Each manipulator tries to build the traffic lines to magnify its “benefit”. Simulation results show a good qualitative agreement with the empirical results.

  5. Transportability in Network Meta-analysis.

    PubMed

    Kabali, Conrad; Ghazipura, Marya

    2016-07-01

    Network meta-analysis is an extension of the conventional pair wise meta-analysis to include treatments that have not been compared head to head. It has in recent years caught the interest of clinical investigators in comparative effectiveness research. While allowing a simultaneous comparison of a large number of treatment effects, an inclusion of indirect effects (i.e., estimating effects using treatments that have not been randomized head to head) may introduce bias. This bias occurs from not accounting for covariates differences in the analysis, in a way that allows transfer of causal information across trials. Although this problem might not be entirely new to network meta-analysis researchers, it has not been given a formal treatment. Occasionally it is tackled by fitting a meta-regression model to account for imbalance of covariates. However, this approach may still produce biased estimates if covariates responsible for disparity across studies are post-treatment variables. To address the problem, we use the graphical method known as transportability to demonstrate whether and how indirect treatment effects can validly be estimated in network meta-analysis. See Video Abstract at http://links.lww.com/EDE/B37. PMID:26963292

  6. Transport link scanner: simulating geographic transport network expansion through individual investments

    NASA Astrophysics Data System (ADS)

    Jacobs-Crisioni, C.; Koopmans, C. C.

    2016-07-01

    This paper introduces a GIS-based model that simulates the geographic expansion of transport networks by several decision-makers with varying objectives. The model progressively adds extensions to a growing network by choosing the most attractive investments from a limited choice set. Attractiveness is defined as a function of variables in which revenue and broader societal benefits may play a role and can be based on empirically underpinned parameters that may differ according to private or public interests. The choice set is selected from an exhaustive set of links and presumably contains those investment options that best meet private operator's objectives by balancing the revenues of additional fare against construction costs. The investment options consist of geographically plausible routes with potential detours. These routes are generated using a fine-meshed regularly latticed network and shortest path finding methods. Additionally, two indicators of the geographic accuracy of the simulated networks are introduced. A historical case study is presented to demonstrate the model's first results. These results show that the modelled networks reproduce relevant results of the historically built network with reasonable accuracy.

  7. Transport link scanner: simulating geographic transport network expansion through individual investments

    NASA Astrophysics Data System (ADS)

    Jacobs-Crisioni, C.; Koopmans, C. C.

    2016-06-01

    This paper introduces a GIS-based model that simulates the geographic expansion of transport networks by several decision-makers with varying objectives. The model progressively adds extensions to a growing network by choosing the most attractive investments from a limited choice set. Attractiveness is defined as a function of variables in which revenue and broader societal benefits may play a role and can be based on empirically underpinned parameters that may differ according to private or public interests. The choice set is selected from an exhaustive set of links and presumably contains those investment options that best meet private operator's objectives by balancing the revenues of additional fare against construction costs. The investment options consist of geographically plausible routes with potential detours. These routes are generated using a fine-meshed regularly latticed network and shortest path finding methods. Additionally, two indicators of the geographic accuracy of the simulated networks are introduced. A historical case study is presented to demonstrate the model's first results. These results show that the modelled networks reproduce relevant results of the historically built network with reasonable accuracy.

  8. Setting Up a Public Use Local Area Network.

    ERIC Educational Resources Information Center

    Flower, Eric; Thulstrup, Lisa

    1988-01-01

    Describes a public use microcomputer cluster at the University of Maine, Orono. Various network topologies, hardware and software options, installation problems, system management, and performance are discussed. (MES)

  9. 78 FR 22026 - Alternative Transportation in Parks and Public Lands Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-12

    ... Federal Transit Administration Alternative Transportation in Parks and Public Lands Program AGENCY... of Federal land management agency transportation investments with public transportation systems that... in the document ``Alternative Transportation in Parks and Public Lands Program: Requirements...

  10. Mode choice between private and public transport in Klang Valley, Malaysia.

    PubMed

    Chiu Chuen, Onn; Karim, Mohamed Rehan; Yusoff, Sumiani

    2014-01-01

    In 2010, Klang Valley has only 17% trips each day were completed using public transport, with the rest of the 83% trips were made through private transport. The inclination towards private car usage will only get worse if the transport policy continues to be inefficient and ineffective. Under the National Key Economic Area, the priority aimed to stimulate the increase of modal share of public transport in the Klang Valley to 50% by 2020. In the 10th Malaysia Plan, the Klang Valley Mass Rapid Transit was proposed, equipped with 141 km of MRT system, and will integrate with the existing rail networks. Nevertheless, adding kilometers into the rail system will not help, if people do not make the shift from private into public transport. This research would like to assess the possible mode shift of travellers in the Klang Valley towards using public transport, based on the utility function of available transport modes. It intends to identify the criteria that will trigger their willingness to make changes in favour of public transport as targeted by the NKEA. PMID:24701165

  11. Mode Choice between Private and Public Transport in Klang Valley, Malaysia

    PubMed Central

    Karim, Mohamed Rehan; Yusoff, Sumiani

    2014-01-01

    In 2010, Klang Valley has only 17% trips each day were completed using public transport, with the rest of the 83% trips were made through private transport. The inclination towards private car usage will only get worse if the transport policy continues to be inefficient and ineffective. Under the National Key Economic Area, the priority aimed to stimulate the increase of modal share of public transport in the Klang Valley to 50% by 2020. In the 10th Malaysia Plan, the Klang Valley Mass Rapid Transit was proposed, equipped with 141 km of MRT system, and will integrate with the existing rail networks. Nevertheless, adding kilometers into the rail system will not help, if people do not make the shift from private into public transport. This research would like to assess the possible mode shift of travellers in the Klang Valley towards using public transport, based on the utility function of available transport modes. It intends to identify the criteria that will trigger their willingness to make changes in favour of public transport as targeted by the NKEA. PMID:24701165

  12. Effect of Transportation Policies on Modal Shift from Private Car to Public Transport in Malaysia

    NASA Astrophysics Data System (ADS)

    Nurdden, Abdullah; Rahmat, Riza Atiq O. K.; Ismail, Amiruddin

    The car is the second (40%) most common mode of transportation in Malaysia. The rapid increase in the use of personal transportation has its roots in the weak Malaysian public transport system. As a result, traffic congestion, accidents, air pollution and need for parking space among other evils, have escalated. In this study, policies aimed at discouraging the use of private transportation were studied. In addition, this study sought to identify factors that prevent personal transport users from utilizing public transport so that rational policies could be formulated to encourage greater utilization of public transport. A survey was carried out on users of private and public (both bus and urban train transport) (n = 1200). A binary logit model was developed for the three alternative modes, Car, Bus and Train. This study found that age, gender, car ownership, travel time, travel cost, household size and income are significant factors in influencing the individual`s choice of transportation. The most important variables found likely to encourage the use of public transport were reduced travel time, reduce the distance from home to public transportation stations and subsidized fares. In conclusion, for the commuter to switch to public transport, proper incentives need to be provided for a successful implementation.

  13. Individual Public Transportation Accessibility is Positively Associated with Self-Reported Active Commuting

    PubMed Central

    Djurhuus, Sune; Hansen, Henning Sten; Aadahl, Mette; Glümer, Charlotte

    2014-01-01

    Background: Active commuters have lower risk of chronic disease. Understanding which of the, to some extent, modifiable characteristics of public transportation that facilitate its use is thus important in a public health perspective. The aim of the study was to examine the association between individual public transportation accessibility and self-reported active commuting, and whether the associations varied with commute distance, age, and gender. Methods: Twenty-eight thousand nine hundred twenty-eight commuters in The Capital Region of Denmark reported self-reported time spent either walking or cycling to work or study each day and the distance to work or study. Data were obtained from the Danish National Health Survey collected in February to April 2010. Individual accessibility by public transportation was calculated using a multi-modal network in a GIS. Multilevel logistic regression was used to analyze the association between accessibility, expressed as access area, and being an active commuter. Results: Public transport accessibility area based on all stops within walking and cycling distance was positively associated with being an active commuter. Distance to work, age, and gender modified the associations. Residing within 10 km commute distance and in areas of high accessibility was associated with being an active commuter and meeting the recommendations of physical activity. For the respondents above 29 years, individual public transportation accessibility was positively associated with being an active commuter. Women having high accessibility had significantly higher odds of being an active commuter compared to having a low accessibility. For men, the associations were insignificant. Conclusion: This study extends the knowledge about the driving forces of using public transportation for commuting by examining the individual public transportation accessibility. Findings suggest that transportation accessibility supports active commuting and planning

  14. ESTABLISHING A NATIONAL ENVIRONMENTAL PUBLIC HEALTH TRACKING NETWORK

    EPA Science Inventory

    This paper describes the CDC's efforts to develop a National Environmental Public Health Tracking Network Tracking Network) with particular focus on air related issues and collaboration with EPA. A Tracking Network is needed in the United States to improve the health of communit...

  15. Survey-Based Measurement of Public Management and Policy Networks

    ERIC Educational Resources Information Center

    Henry, Adam Douglas; Lubell, Mark; McCoy, Michael

    2012-01-01

    Networks have become a central concept in the policy and public management literature; however, theoretical development is hindered by a lack of attention to the empirical properties of network measurement methods. This paper compares three survey-based methods for measuring organizational networks: the roster, the free-recall name generator, and…

  16. Anomalous motor mediated cargo transport in microtubule networks

    NASA Astrophysics Data System (ADS)

    Vandal, Steven; Macveigh-Fierro, Daniel; Shen, Zhiyuan; Lemoi, Kyle; Vidali, Luis; Ross, Jennifer; Tuzel, Erkan

    Cargo transport is an important biological mechanism by which cells locomote, self-organize, and actively transport organelles. This transport is mediated by the cytoskeletal network and molecular motors; however, it is not known how network self-organization and dynamics affect these transport processes. In order to develop a mechanistic understanding of cargo transport, we use a coarse-grained Brownian dynamics model that incorporates the dynamics of these networks, as well as experimentally determined motor properties. We will test these models with two experimental systems: (1) in vitro microtubule networks with kinesin-1 motors, and quantum dot cargos on recreated microtubule networks, and (2) an excellent model organism, the moss Physcomitrella patens, in which chloroplasts are transported via the microtubule network by means of kinesin-like proteins. Phenomenological network characterizations are made, both in vivo and in vitro, and cargo motility is characterized using Mean Squared Displacement (MSD) measurements. Our simulations shed light on the role of network density and motor properties on the observed transport behavior, and improve our understanding of cargo transport in cells.

  17. Flow networks: A characterization of geophysical fluid transport

    NASA Astrophysics Data System (ADS)

    Ser-Giacomi, Enrico; Rossi, Vincent; López, Cristóbal; Hernández-García, Emilio

    2015-03-01

    We represent transport between different regions of a fluid domain by flow networks, constructed from the discrete representation of the Perron-Frobenius or transfer operator associated to the fluid advection dynamics. The procedure is useful to analyze fluid dynamics in geophysical contexts, as illustrated by the construction of a flow network associated to the surface circulation in the Mediterranean sea. We use network-theory tools to analyze the flow network and gain insights into transport processes. In particular, we quantitatively relate dispersion and mixing characteristics, classically quantified by Lyapunov exponents, to the degree of the network nodes. A family of network entropies is defined from the network adjacency matrix and related to the statistics of stretching in the fluid, in particular, to the Lyapunov exponent field. Finally, we use a network community detection algorithm, Infomap, to partition the Mediterranean network into coherent regions, i.e., areas internally well mixed, but with little fluid interchange between them.

  18. Synchronization analysis of complex networks with multi-weights and its application in public traffic network

    NASA Astrophysics Data System (ADS)

    An, Xin-lei; Zhang, Li; Li, Yin-zhen; Zhang, Jian-gang

    2014-10-01

    On the basis of traditional weighted network, we study a new complex network model with multi-weights, which has one or several different types of weights between any two nodes. According to the method of network split, we split the complex network with multi-weights into several different complex networks with single weight, and study its global synchronization. Taking bus lines as the network nodes, a new public traffic roads network model with multi-weights is established by the proposed network model and space R modeling approach. Then based on the Lyapunov stability theory, the criteria is designed for the global synchronization of the public traffic roads networks with multi-weights. By changing the different weights and taking the Lorenz chaotic system for example, some numerical examples are given to discuss the balance of the whole public traffic roads network.

  19. Going Public: Networking Globally and Locally

    ERIC Educational Resources Information Center

    Sachs, Carolyn E.

    2007-01-01

    Rural sociologists figure prominently in the move towards public sociology. The paper takes up Michael Burawoy's call for public sociology and discusses what rural sociologists have to offer to publics and how we stand to gain as a discipline in working with publics. The paper argues that rural sociologists' ability to adopt a cosmopolitan view…

  20. The influence of transport network vulnerability for maritime ports

    NASA Astrophysics Data System (ADS)

    Ruscă, F.; Roşca, E.; Rusca, A.; Roşca, M.; Burciu, S.

    2015-11-01

    The concepts of reliability and vulnerability are quite important in assessing the ability of transport networks from land to provide continuity in operation tacking in consideration the relation with seaports. Transport infrastructure modernizing and extension according to land use and sustainable development requirements still represents a challenging issue among policy makers, regional/local communities and scientists. The interest for the researches reliability and vulnerability for transport networks who connect maritime ports with interior city's is generate by the natural disasters, the terrorist acts, unconventional war, etc.. Transport network modelling enable the development of mathematical models used in evaluating the reliability and vulnerability. Nodes or link disruption could have an important impact over transport network users. In our paper we investigates the Romanian road network vulnerability related to Danube crossing versus maritime ports (Constanta and Mangalia) and its mitigation by improving network topology. We use Visum software to promote a methodology to assess road transport network vulnerability versus Romanian seaports and we propose some solutions to reduce probability of road transport network to fail.

  1. 78 FR 19024 - Lithium Ion Batteries in Transportation Public Forum

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-28

    ... SAFETY BOARD Lithium Ion Batteries in Transportation Public Forum On Thursday and Friday, April 11-12, 2013, the National Transportation Safety Board (NTSB) will convene a forum titled, ``Lithium Ion... Inquiry. The forum is organized into three topic areas: Lithium ion battery design, development, and...

  2. Public authority control strategy for opinion evolution in social networks

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Xiong, Xi; Zhang, Minghong; Li, Wei

    2016-08-01

    This paper addresses the need to deal with and control public opinion and rumors. Existing strategies to control public opinion include degree, random, and adaptive bridge control strategies. In this paper, we use the HK model to present a public opinion control strategy based on public authority (PA). This means utilizing the influence of expert or high authority individuals whose opinions we control to obtain the optimum effect in the shortest time possible and thus reach a consensus of public opinion. Public authority (PA) is only influenced by individuals' attributes (age, economic status, and education level) and not their degree distribution; hence, in this paper, we assume that PA complies with two types of public authority distribution (normal and power-law). According to the proposed control strategy, our experiment is based on random, degree, and public authority control strategies in three different social networks (small-world, scale-free, and random) and we compare and analyze the strategies in terms of convergence time (T), final number of controlled agents (C), and comprehensive efficiency (E). We find that different network topologies and the distribution of the PA in the network can influence the final controlling effect. While the effect of PA strategy differs in different network topology structures, all structures achieve comprehensive efficiency with any kind of public authority distribution in any network. Our findings are consistent with several current sociological phenomena and show that in the process of public opinion/rumor control, considerable attention should be paid to high authority individuals.

  3. Public authority control strategy for opinion evolution in social networks.

    PubMed

    Chen, Xi; Xiong, Xi; Zhang, Minghong; Li, Wei

    2016-08-01

    This paper addresses the need to deal with and control public opinion and rumors. Existing strategies to control public opinion include degree, random, and adaptive bridge control strategies. In this paper, we use the HK model to present a public opinion control strategy based on public authority (PA). This means utilizing the influence of expert or high authority individuals whose opinions we control to obtain the optimum effect in the shortest time possible and thus reach a consensus of public opinion. Public authority (PA) is only influenced by individuals' attributes (age, economic status, and education level) and not their degree distribution; hence, in this paper, we assume that PA complies with two types of public authority distribution (normal and power-law). According to the proposed control strategy, our experiment is based on random, degree, and public authority control strategies in three different social networks (small-world, scale-free, and random) and we compare and analyze the strategies in terms of convergence time (T), final number of controlled agents (C), and comprehensive efficiency (E). We find that different network topologies and the distribution of the PA in the network can influence the final controlling effect. While the effect of PA strategy differs in different network topology structures, all structures achieve comprehensive efficiency with any kind of public authority distribution in any network. Our findings are consistent with several current sociological phenomena and show that in the process of public opinion/rumor control, considerable attention should be paid to high authority individuals. PMID:27586601

  4. Sovereign public debt crisis in Europe. A network analysis

    NASA Astrophysics Data System (ADS)

    Matesanz, David; Ortega, Guillermo J.

    2015-10-01

    In this paper we analyse the evolving network structure of the quarterly public debt-to-GDP ratio from 2000 to 2014. By applying tools and concepts coming from complex systems we study the effects of the global financial crisis over public debt network connections and communities. Two main results arise from this analysis: firstly, countries public debts tend to synchronize their evolution, increasing global connectivity in the network and dramatically decreasing the number of communities. Secondly, a disruption in previous structure is observed at the time of the shock, emerging a more centralized and less diversify network topological organization which might be more prone to suffer contagion effects. This last fact is evidenced by an increasing tendency in countries of similar level of public debt to be connected between them, which we have quantified by the network assortativity.

  5. A Comparison of Geographic Information Systems, Complex Networks, and Other Models for Analyzing Transportation Network Topologies

    NASA Technical Reports Server (NTRS)

    Alexandrov, Natalia (Technical Monitor); Kuby, Michael; Tierney, Sean; Roberts, Tyler; Upchurch, Christopher

    2005-01-01

    This report reviews six classes of models that are used for studying transportation network topologies. The report is motivated by two main questions. First, what can the "new science" of complex networks (scale-free, small-world networks) contribute to our understanding of transport network structure, compared to more traditional methods? Second, how can geographic information systems (GIS) contribute to studying transport networks? The report defines terms that can be used to classify different kinds of models by their function, composition, mechanism, spatial and temporal dimensions, certainty, linearity, and resolution. Six broad classes of models for analyzing transport network topologies are then explored: GIS; static graph theory; complex networks; mathematical programming; simulation; and agent-based modeling. Each class of models is defined and classified according to the attributes introduced earlier. The paper identifies some typical types of research questions about network structure that have been addressed by each class of model in the literature.

  6. Topology and energy transport in networks of interacting photosynthetic complexes

    NASA Astrophysics Data System (ADS)

    Allegra, Michele; Giorda, Paolo

    2012-05-01

    We address the role of topology in the energy transport process that occurs in networks of photosynthetic complexes. We take inspiration from light-harvesting networks present in purple bacteria and simulate an incoherent dissipative energy transport process on more general and abstract networks, considering both regular structures (Cayley trees and hyperbranched fractals) and randomly generated ones. We focus on the the two primary light-harvesting complexes of purple bacteria, i.e., the LH1 and LH2, and we use network-theoretical centrality measures in order to select different LH1 arrangements. We show that different choices cause significant differences in the transport efficiencies, and that for regular networks, centrality measures allow us to identify arrangements that ensure transport efficiencies which are better than those obtained with a random disposition of the complexes. The optimal arrangements strongly depend on the dissipative nature of the dynamics and on the topological properties of the networks considered, and depending on the latter, they are achieved by using global versus local centrality measures. For randomly generated networks, a random arrangement of the complexes already provides efficient transport, and this suggests the process is strong with respect to limited amount of control in the structure design and to the disorder inherent in the construction of randomly assembled structures. Finally, we compare the networks considered with the real biological networks and find that the latter have in general better performances, due to their higher connectivity, but the former with optimal arrangements can mimic the real networks' behavior for a specific range of transport parameters. These results show that the use of network-theoretical concepts can be crucial for the characterization and design of efficient artificial energy transport networks.

  7. 76 FR 44394 - Public Transportation on Indian Reservations Program; Tribal Transit Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-25

    ... Federal Transit Administration Public Transportation on Indian Reservations Program; Tribal Transit... availability of $15,075,000 in funding provided by the Public Transportation on Indian Reservations Program... establishing the Public Transportation on Indian Reservations Program (Tribal Transit Program) (TTP)....

  8. 77 FR 547 - Fiscal Year 2011 Public Transportation on Indian Reservations Program Project Selections

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-05

    ... Federal Transit Administration Fiscal Year 2011 Public Transportation on Indian Reservations Program... Administration (FTA) announces the selection of projects funded with Section 5311 (c), Public Transportation on... of capital projects, operating costs, and planning activities for public transportation services...

  9. 77 FR 51106 - Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-23

    ... Federal Transit Administration Limitation on Claims Against Proposed Public Transportation Projects AGENCY... FTA actions announced herein for the listed public transportation project will be barred unless the... final agency actions by issuing certain approvals for the public transportation project listed...

  10. Public Access; Public Interest. The Network Project. Notebook Number 11.

    ERIC Educational Resources Information Center

    Columbia Univ., New York, NY. Network Project.

    The transcript of a panel discussion and an essay on public access to and control of society's information resources are presented. It is contended that the electronic Media--including radio, television, and communication satellites--are controlled by a select group of individuals and corporations and that they are not meeting the public interest.…

  11. Social network analysis of public health programs to measure partnership.

    PubMed

    Schoen, Martin W; Moreland-Russell, Sarah; Prewitt, Kim; Carothers, Bobbi J

    2014-12-01

    In order to prevent chronic diseases, community-based programs are encouraged to take an ecological approach to public health promotion and involve many diverse partners. Little is known about measuring partnership in implementing public health strategies. We collected data from 23 Missouri communities in early 2012 that received funding from three separate programs to prevent obesity and/or reduce tobacco use. While all of these funding programs encourage partnership, only the Social Innovation for Missouri (SIM) program included a focus on building community capacity and enhancing collaboration. Social network analysis techniques were used to understand contact and collaboration networks in community organizations. Measurements of average degree, density, degree centralization, and betweenness centralization were calculated for each network. Because of the various sizes of the networks, we conducted comparative analyses with and without adjustment for network size. SIM programs had increased measurements of average degree for partner collaboration and larger networks. When controlling for network size, SIM groups had higher measures of network density and lower measures of degree centralization and betweenness centralization. SIM collaboration networks were more dense and less centralized, indicating increased partnership. The methods described in this paper can be used to compare partnership in community networks of various sizes. Further research is necessary to define causal mechanisms of partnership development and their relationship to public health outcomes. PMID:25462609

  12. Large-Scale Public Transcriptomic Data Mining Reveals a Tight Connection between the Transport of Nitrogen and Other Transport Processes in Arabidopsis.

    PubMed

    He, Fei; Karve, Abhijit A; Maslov, Sergei; Babst, Benjamin A

    2016-01-01

    Movement of nitrogen to the plant tissues where it is needed for growth is an important contribution to nitrogen use efficiency. However, we have very limited knowledge about the mechanisms of nitrogen transport. Loading of nitrogen into the xylem and/or phloem by transporter proteins is likely important, but there are several families of genes that encode transporters of nitrogenous molecules (collectively referred to as N transporters here), each comprised of many gene members. In this study, we leveraged publicly available microarray data of Arabidopsis to investigate the gene networks of N transporters to elucidate their possible biological roles. First, we showed that tissue-specificity of nitrogen (N) transporters was well reflected among the public microarray data. Then, we built coexpression networks of N transporters, which showed relationships between N transporters and particular aspects of plant metabolism, such as phenylpropanoid biosynthesis and carbohydrate metabolism. Furthermore, genes associated with several biological pathways were found to be tightly coexpressed with N transporters in different tissues. Our coexpression networks provide information at the systems-level that will serve as a resource for future investigation of nitrogen transport systems in plants, including candidate gene clusters that may work together in related biological roles. PMID:27563305

  13. Large-Scale Public Transcriptomic Data Mining Reveals a Tight Connection between the Transport of Nitrogen and Other Transport Processes in Arabidopsis

    PubMed Central

    He, Fei; Karve, Abhijit A.; Maslov, Sergei; Babst, Benjamin A.

    2016-01-01

    Movement of nitrogen to the plant tissues where it is needed for growth is an important contribution to nitrogen use efficiency. However, we have very limited knowledge about the mechanisms of nitrogen transport. Loading of nitrogen into the xylem and/or phloem by transporter proteins is likely important, but there are several families of genes that encode transporters of nitrogenous molecules (collectively referred to as N transporters here), each comprised of many gene members. In this study, we leveraged publicly available microarray data of Arabidopsis to investigate the gene networks of N transporters to elucidate their possible biological roles. First, we showed that tissue-specificity of nitrogen (N) transporters was well reflected among the public microarray data. Then, we built coexpression networks of N transporters, which showed relationships between N transporters and particular aspects of plant metabolism, such as phenylpropanoid biosynthesis and carbohydrate metabolism. Furthermore, genes associated with several biological pathways were found to be tightly coexpressed with N transporters in different tissues. Our coexpression networks provide information at the systems-level that will serve as a resource for future investigation of nitrogen transport systems in plants, including candidate gene clusters that may work together in related biological roles. PMID:27563305

  14. Complex Network Theory Applied to the Growth of Kuala Lumpur’s Public Urban Rail Transit Network

    PubMed Central

    Ding, Rui; Ujang, Norsidah; Hamid, Hussain bin; Wu, Jianjun

    2015-01-01

    Recently, the number of studies involving complex network applications in transportation has increased steadily as scholars from various fields analyze traffic networks. Nonetheless, research on rail network growth is relatively rare. This research examines the evolution of the Public Urban Rail Transit Networks of Kuala Lumpur (PURTNoKL) based on complex network theory and covers both the topological structure of the rail system and future trends in network growth. In addition, network performance when facing different attack strategies is also assessed. Three topological network characteristics are considered: connections, clustering and centrality. In PURTNoKL, we found that the total number of nodes and edges exhibit a linear relationship and that the average degree stays within the interval [2.0488, 2.6774] with heavy-tailed distributions. The evolutionary process shows that the cumulative probability distribution (CPD) of degree and the average shortest path length show good fit with exponential distribution and normal distribution, respectively. Moreover, PURTNoKL exhibits clear cluster characteristics; most of the nodes have a 2-core value, and the CPDs of the centrality’s closeness and betweenness follow a normal distribution function and an exponential distribution, respectively. Finally, we discuss four different types of network growth styles and the line extension process, which reveal that the rail network’s growth is likely based on the nodes with the biggest lengths of the shortest path and that network protection should emphasize those nodes with the largest degrees and the highest betweenness values. This research may enhance the networkability of the rail system and better shape the future growth of public rail networks. PMID:26448645

  15. A manipulator game model of urban public traffic network

    NASA Astrophysics Data System (ADS)

    Chang, Hui; Xu, Xiu-Lian; Hu, Chin-Kun; Fu, Chunhua; Feng, Ai-xia; He, Da-Ren

    2014-12-01

    Urban public traffic networks are typical complex systems. Understanding their evolution mechanism attracts much attention in recent years. Here, we propose that the evolution of urban public traffic network can be considered as a game process between two network manipulators, i.e., passengers and company, and the equilibrium solution to the game determines the steady-state behavior of the network. Both analytical solution and numerical simulations to such game model can well describe the empirical data collected from the urban public traffic systems in four Chinese cities (Beijing, Shanghai, Nanjing, and Hangzhou) and the Boston subway. Our results suggest that the manipulator game model grasps the fundamental characteristics of the evolution mechanism of the urban public traffic systems. Similar idea may be extended to other complex systems which have small number of manipulators.

  16. CT Image Processing Using Public Digital Networks

    PubMed Central

    Rhodes, Michael L.; Azzawi, Yu-Ming; Quinn, John F.; Glenn, William V.; Rothman, Stephen L.G.

    1984-01-01

    Nationwide commercial computer communication is now commonplace for those applications where digital dialogues are generally short and widely distributed, and where bandwidth does not exceed that of dial-up telephone lines. Image processing using such networks is prohibitive because of the large volume of data inherent to digital pictures. With a blend of increasing bandwidth and distributed processing, network image processing becomes possible. This paper examines characteristics of a digital image processing service for a nationwide network of CT scanner installations. Issues of image transmission, data compression, distributed processing, software maintenance, and interfacility communication are also discussed. Included are results that show the volume and type of processing experienced by a network of over 50 CT scanners for the last 32 months.

  17. Home vs. Public Schoolers' Relationships: Differences in Social Networks.

    ERIC Educational Resources Information Center

    Chatham-Carpenter, April D.

    Noting the lack of basic information necessary to begin to make conclusions about a home schooled child's social contacts, a study investigated the social networks of home vs. public schooled children (with a child's "social network" defined as all of the people who interact on a regular basis with the child at least once a month). The subject…

  18. Universality at Breakdown of Quantum Transport on Complex Networks.

    PubMed

    Kulvelis, Nikolaj; Dolgushev, Maxim; Mülken, Oliver

    2015-09-18

    We consider single-particle quantum transport on parametrized complex networks. Based on general arguments regarding the spectrum of the corresponding Hamiltonian, we derive bounds for a measure of the global transport efficiency defined by the time-averaged return probability. For treelike networks, we show analytically that a transition from efficient to inefficient transport occurs depending on the (average) functionality of the nodes of the network. In the infinite system size limit, this transition can be characterized by an exponent which is universal for all treelike networks. Our findings are corroborated by analytic results for specific deterministic networks, dendrimers and Vicsek fractals, and by Monte Carlo simulations of iteratively built scale-free trees. PMID:26430977

  19. Universality at Breakdown of Quantum Transport on Complex Networks

    NASA Astrophysics Data System (ADS)

    Kulvelis, Nikolaj; Dolgushev, Maxim; Mülken, Oliver

    2015-09-01

    We consider single-particle quantum transport on parametrized complex networks. Based on general arguments regarding the spectrum of the corresponding Hamiltonian, we derive bounds for a measure of the global transport efficiency defined by the time-averaged return probability. For treelike networks, we show analytically that a transition from efficient to inefficient transport occurs depending on the (average) functionality of the nodes of the network. In the infinite system size limit, this transition can be characterized by an exponent which is universal for all treelike networks. Our findings are corroborated by analytic results for specific deterministic networks, dendrimers and Vicsek fractals, and by Monte Carlo simulations of iteratively built scale-free trees.

  20. Performance evaluation of transport protocols for networked haptic collaboration

    NASA Astrophysics Data System (ADS)

    Lee, Seokhee; Moon, Sungtae; Kim, JongWon

    2006-10-01

    In this paper, we explain two transport-related experimental results for networked haptic CVEs (collaborative virtual environments). The first set of experiments evaluate the performance changes in terms of QoE (quality of experience) with the haptic-based CVEs under different network settings. The evaluation results are then used to define the minimum networking requirements for CVEs with force-feedback haptic interface. The second experiments verify whether the existing haptics-specialized transport protocols can satisfy the networking QoE requirements for the networked haptic CVEs. The results will be used to suggest in design guidelines for an effective transport protocol for this highly-interactive (i.e., extremely low-delay latency at up to 1 kHz processing cycle) haptic CVEs over the delay-crippled Internet.

  1. 49 CFR 37.61 - Public transportation programs and activities in existing facilities.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 1 2013-10-01 2013-10-01 false Public transportation programs and activities in existing facilities. 37.61 Section 37.61 Transportation Office of the Secretary of Transportation TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.61 Public transportation programs and activities...

  2. 49 CFR 37.43 - Alteration of transportation facilities by public entities.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 1 2013-10-01 2013-10-01 false Alteration of transportation facilities by public entities. 37.43 Section 37.43 Transportation Office of the Secretary of Transportation TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.43 Alteration of transportation facilities by public entities....

  3. 49 CFR 37.41 - Construction of transportation facilities by public entities.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 1 2013-10-01 2013-10-01 false Construction of transportation facilities by public entities. 37.41 Section 37.41 Transportation Office of the Secretary of Transportation TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.41 Construction of transportation facilities by public entities....

  4. Viscoelastic properties of actin networks influence material transport

    NASA Astrophysics Data System (ADS)

    Stam, Samantha; Weirich, Kimberly; Gardel, Margaret

    2015-03-01

    Directed flows of cytoplasmic material are important in a variety of biological processes including assembly of a mitotic spindle, retraction of the cell rear during migration, and asymmetric cell division. Networks of cytoskeletal polymers and molecular motors are known to be involved in these events, but how the network mechanical properties are tuned to perform such functions is not understood. Here, we construct networks of either semiflexible actin filaments or rigid bundles with varying connectivity. We find that solutions of rigid rods, where unimpeded sliding of filaments may enhance transport in comparison to unmoving tracks, are the fastest at transporting network components. Entangled solutions of semiflexible actin filaments also transport material, but the entanglements provide resistance. Increasing the elasticity of the actin networks with crosslinking proteins slows network deformation further. However, the length scale of correlated transport in these networks is increased. Our results reveal how the rigidity and connectivity of biopolymers allows material transport to occur over time and length scales required for physiological processes. This work was supported by the U. Chicago MRSEC

  5. Implications of Network Structure on Public Health Collaboratives

    ERIC Educational Resources Information Center

    Retrum, Jessica H.; Chapman, Carrie L.; Varda, Danielle M.

    2013-01-01

    Interorganizational collaboration is an essential function of public health agencies. These partnerships form social networks that involve diverse types of partners and varying levels of interaction. Such collaborations are widely accepted and encouraged, yet very little comparative research exists on how public health partnerships develop and…

  6. A GIS Tool for simulating Nitrogen transport along schematic Network

    NASA Astrophysics Data System (ADS)

    Tavakoly, A. A.; Maidment, D. R.; Yang, Z.; Whiteaker, T.; David, C. H.; Johnson, S.

    2012-12-01

    An automated method called the Arc Hydro Schematic Processor has been developed for water process computation on schematic networks formed from the NHDPlus and similar GIS river networks. The sechemtaic network represents the hydrologic feature on the ground and is a network of links and nodes. SchemaNodes show hydrologic features, such as catchments or stream junctions. SchemaLinks prescripe the connections between nodes. The schematic processor uses the schematic network to pass informatin through a watershed and move water or pollutants dwonstream. In addition, the schematic processor has a capability to use additional programming applied to the passed and/or received values and manipulating data trough network. This paper describes how the schemtic processor can be used to simulate nitrogen transport and transformation on river networks. For this purpose the nitrogen loads is estimated on the NHDPlus river network using the Schematic Processor coupled with the river routing model for the Texas Gulf Coast Hydrologic Region.

  7. 49 CFR 37.43 - Alteration of transportation facilities by public entities.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Alteration of transportation facilities by public... transportation facilities by public entities. (a)(1) When a public entity alters an existing facility or a part of an existing facility used in providing designated public transportation services in a way...

  8. 49 CFR 37.43 - Alteration of transportation facilities by public entities.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 1 2012-10-01 2012-10-01 false Alteration of transportation facilities by public... transportation facilities by public entities. (a)(1) When a public entity alters an existing facility or a part of an existing facility used in providing designated public transportation services in a way...

  9. 49 CFR 37.41 - Construction of transportation facilities by public entities.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... public entities. 37.41 Section 37.41 Transportation Office of the Secretary of Transportation... transportation facilities by public entities. (a) A public entity shall construct any new facility to be used in providing designated public transportation services so that the facility is readily accessible to and...

  10. 49 CFR 37.43 - Alteration of transportation facilities by public entities.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 1 2011-10-01 2011-10-01 false Alteration of transportation facilities by public... transportation facilities by public entities. (a)(1) When a public entity alters an existing facility or a part of an existing facility used in providing designated public transportation services in a way...

  11. 49 CFR 37.41 - Construction of transportation facilities by public entities.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... public entities. 37.41 Section 37.41 Transportation Office of the Secretary of Transportation... transportation facilities by public entities. (a) A public entity shall construct any new facility to be used in providing designated public transportation services so that the facility is readily accessible to and...

  12. 49 CFR 37.43 - Alteration of transportation facilities by public entities.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 1 2014-10-01 2014-10-01 false Alteration of transportation facilities by public... transportation facilities by public entities. (a)(1) When a public entity alters an existing facility or a part of an existing facility used in providing designated public transportation services in a way...

  13. 49 CFR 37.41 - Construction of transportation facilities by public entities.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... public entities. 37.41 Section 37.41 Transportation Office of the Secretary of Transportation... transportation facilities by public entities. (a) A public entity shall construct any new facility to be used in providing designated public transportation services so that the facility is readily accessible to and...

  14. 49 CFR 37.41 - Construction of transportation facilities by public entities.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... public entities. 37.41 Section 37.41 Transportation Office of the Secretary of Transportation... transportation facilities by public entities. (a) A public entity shall construct any new facility to be used in providing designated public transportation services so that the facility is readily accessible to and...

  15. Attacks on public telephone networks: technologies and challenges

    NASA Astrophysics Data System (ADS)

    Kosloff, T.; Moore, Tyler; Keller, J.; Manes, Gavin W.; Shenoi, Sujeet

    2003-09-01

    Signaling System 7 (SS7) is vital to signaling and control in America's public telephone networks. This paper describes a class of attacks on SS7 networks involving the insertion of malicious signaling messages via compromised SS7 network components. Three attacks are discussed in detail: IAM flood attacks, redirection attacks and point code spoofing attacks. Depending on their scale of execution, these attacks can produce effects ranging from network congestion to service disruption. Methods for detecting these denial-of-service attacks and mitigating their effects are also presented.

  16. Transport in two-dimensional paper networks

    PubMed Central

    Fu, Elain; Ramsey, Stephen A.; Kauffman, Peter; Lutz, Barry; Yager, Paul

    2011-01-01

    Two-dimensional paper networks (2DPNs) hold great potential for transcending the capabilities and performance of today's paper-based analytical devices. Specifically, 2DPNs enable sophisticated multi-step chemical processing sequences for sample pretreatment and analysis at a cost and ease-of-use that make them appropriate for use in settings with low resources. A quantitative understanding of flow in paper networks is essential to realizing the potential of these networks. In this report, we provide a framework for understanding flow in simple 2DPNs using experiments, analytical expressions, and computational simulations. PMID:22140373

  17. 49 CFR 37.61 - Public transportation programs and activities in existing facilities.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 1 2014-10-01 2014-10-01 false Public transportation programs and activities in... TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.61 Public transportation programs and activities in existing facilities. (a) A public entity shall operate a...

  18. 49 CFR 37.61 - Public transportation programs and activities in existing facilities.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Public transportation programs and activities in... TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.61 Public transportation programs and activities in existing facilities. (a) A public entity shall operate a...

  19. 49 CFR 37.61 - Public transportation programs and activities in existing facilities.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 1 2012-10-01 2012-10-01 false Public transportation programs and activities in... TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.61 Public transportation programs and activities in existing facilities. (a) A public entity shall operate a...

  20. 49 CFR 37.61 - Public transportation programs and activities in existing facilities.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 1 2011-10-01 2011-10-01 false Public transportation programs and activities in... TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.61 Public transportation programs and activities in existing facilities. (a) A public entity shall operate a...

  1. A fracture network model for water flow and solute transport

    SciTech Connect

    Robinson, B.A.

    1989-01-01

    This paper summarizes code development work and sample calculations for FRACNET, a two-dimensional steady state simulator of fluid flow and solute transport in fractured porous media. The model analyzes flow and transport by generating a fracture network based on statistical characteristics of fractures obtained from well logs and other data. After a network is generated, flow and tracer transport are computed for appropriate boundary conditions and wellbore source/sink terms. In addition, for a given realization, the code can be used to indicate whether the medium can be treated as an equivalent porous medium. 18 refs., 7 figs.

  2. A simulation study of the impact of the public-private partnership strategy on the performance of transport infrastructure.

    PubMed

    Huang, Zhengfeng; Zheng, Pengjun; Ma, Yanqiang; Li, Xuan; Xu, Wenjun; Zhu, Wanlu

    2016-01-01

    The choice of investment strategy has a great impact on the performance of transport infrastructure. Positive projects such as the "Subway plus Property" model in Hong Kong have created sustainable financial profits for the public transport projects. Owing to a series of public debt and other constraints, public-private partnership (PPP) was introduced as an innovative investment model to address this issue and help develop transport infrastructure. Yet, few studies provide a deeper understanding of relationships between PPP strategy and the performance of such transport projects (particularly the whole transport system). This paper defines the research scope as a regional network of freeway. With a popular PPP model, travel demand prediction method, and relevant parameters as input, agents in a simulation framework can simulate the choice of PPP freeway over time. The simulation framework can be used to analyze the relationship between the PPP strategy and performance of the regional freeway network. This study uses the Freeway Network of Yangtze River Delta (FN-YRD) in China as the context. The results demonstrate the value of using simulation models of complex transportation systems to help decision makers choose the right PPP projects. Such a tool is viewed as particularly important given the ongoing transformation of functions of the Chinese transportation sector, including franchise rights of transport projects, and freeway charging mechanism. PMID:27386401

  3. Common Mental Disorders in Public Transportation Drivers in Lima, Peru

    PubMed Central

    Samalvides, Frine; Vega-Dienstmaier, Johann; Kruger, Hever

    2014-01-01

    Background Traffic related injuries are leading contributors to burden of disease worldwide. In developing countries a high proportion of them can be attributed to public transportation vehicles. Several mental disorders including alcohol and drug abuse, psychotic disorders, mental stress, productivity pressure, and low monetary income were found predictors of high rates of traffic related injuries in public transportation drivers. The goal of this study was to estimate the prevalence of common mental disorders in the population of public transportation drivers of buses and rickshaws in Lima, Peru. Methodology/Principal Findings Cross sectional study. A sample of bus and rickshaw drivers was systematically selected from formal public transportation companies using a snowball approach. Participants completed self-administered questionnaires for assessing major depressive episode, anxiety symptoms, alcohol abuse, and burnout syndrome. Socio demographic information was also collected. The analyses consisted of descriptive measurement of outcomes taking into account both between and within cluster standard deviation (BCSD and WCSD). A total of 278 bus and 227 rickshaw drivers out of 25 companies agreed to participate in the study. BCSD for major depressive episode, anxiety symptoms and burnout syndrome was not found significant (p>0.05). The estimated prevalence of each variable was 13.7% (IC95%: 10.7–16.6%), 24.1% (IC95%: 19.4–28.8%) and 14.1% (IC95%: 10.8–17.4%) respectively. The estimated prevalence of alcohol abuse was 75.4% (IC95%: 69–81.7%, BCSD = 12.2%, WCSD = 41.9%, intra class correlation (ICC): 7.8%). Conclusion Common mental disorders such as alcohol abuse, major depressive episode, anxiety symptoms and burnout syndrome presented higher rates in public transportation drivers than general population. PMID:24979057

  4. Competition and cooperation between active intra-network and passive extra-network transport processes

    PubMed Central

    Maruyama, Dan; Zochowski, Michal

    2014-01-01

    Many networks are embedded in physical space and often interact with it. This interaction can be exemplified through constraints exerted on network topology, or through interactions of processes defined on a network with those that are linked to the space that the network is embedded within, leading to complex dynamics. Here we discuss an example of such an interaction in which a signaling agent is actively transported through the network edges and, at the same time, spreads passively through space due to diffusion. We show that these two processes cooperate or compete depending on the network topology leading to complex dynamics. PMID:24920178

  5. Efficiency of transportation on weighted extended Koch networks

    NASA Astrophysics Data System (ADS)

    Wu, Zikai; Hou, Baoyu; Zhang, Hongjuan

    2013-10-01

    In this paper, we propose a family of weighted extended Koch networks based on a class of extended Koch networks. They originate from a r-complete graph, and each node in each r-complete graph of current generation produces mr-complete graphs whose weighted edges are scaled by factor h in subsequent evolutionary step. We study the structural properties of these networks and random walks on them. In more detail, we calculate exactly the average weighted shortest path length (AWSP), average receiving time (ART) and average sending time (AST). Besides, the technique of resistor network is employed to uncover the relationship between ART and AST on networks with unit weight. In the infinite network order limit, the average weighted shortest path lengths stay bounded with growing network order (0 < h < 1). The closed form expression of ART shows that it exhibits a sub-linear dependence (0 < h < 1) or linear dependence ( h = 1) on network order. On the contrary, the AST behaves super-linearly with the network order. Collectively, all the obtained results show that the efficiency of message transportation on weighted extended Koch networks has close relation to the network parameters h, m and r. All these findings could shed light on the structure and random walks of general weighted networks.

  6. The accelerated growth of the worldwide air transportation network

    NASA Astrophysics Data System (ADS)

    Azzam, Mark; Klingauf, Uwe; Zock, Alexander

    2013-01-01

    Mobility by means of air transportation has a critical impact on the global economy. Especially against the backdrop of further growth and an aggravation of the energy crisis, it is crucial to design a sustainable air transportation system. Current approaches focus on air traffic management. Nevertheless, also the historically evolved network offers great potential for an optimized redesign. But the understanding of its complex structure and development is limited, although modern network science supplies a great set of new methods and tools. So far studies analyzing air transportation as a complex network are based on divers and poor data, which are either merely regional or strongly bounded time-wise. As a result, the current state of research is rather inconsistent regarding topological coefficients and incomplete regarding network evolution. Therefore, we use the historical, worldwide OAG flight schedules data between 1979 and 2007 for our study. Through analyzing by far the most comprehensive data base so far, a better understanding of the network, its evolution and further implications is being provided. To our knowledge we present the first study to determine that the degree distribution of the worldwide air transportation network is non-stationary and is subject to densification and accelerated growth, respectively.

  7. Social Networking for Emergency Management and Public Safety

    SciTech Connect

    Lesperance, Ann M.; Olson, Jarrod; Godinez, Melanie A.

    2010-08-31

    On March 10, 2010 the workshop titled Social Networking for Emergency Management and Public Safety was held in Seattle, WA. The objective of this workshop was to showcase ways social media networking technologies can be used to support emergency management and public safety operations. The workshop highlighted the current state of social networking and where this dynamic engagement is heading, demonstrated some of the more commonly used technologies, highlighted case studies on how these tools have been used in a variety of jurisdictions and engaged the private sector on how these tools might serve as a conduit for two way communication between with the public sector to address regional recovery issues and decision making.

  8. 75 FR 63534 - International Standards on the Transport of Dangerous Goods; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-15

    ..., International Transportation Specialist, Office of Hazardous Materials Safety, Department of Transportation... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION...), Department of Transportation. ACTION: Notice of public meeting. SUMMARY: This notice is to advise...

  9. A design methodology for evolutionary air transportation networks

    NASA Astrophysics Data System (ADS)

    Yang, Eunsuk

    The air transportation demand at large hubs in the U.S. is anticipated to double in the near future. Current runway construction plans at selected airports can relieve some capacity and delay problems, but many are doubtful that this solution is sufficient to accommodate the anticipated demand growth in the National Airspace System (NAS). With the worsening congestion problem, it is imperative to seek alternative solutions other than costly runway constructions. In this respect, many researchers and organizations have been building models and performing analyses of the NAS. However, the complexity and size of the problem results in an overwhelming task for transportation system modelers. This research seeks to compose an active design algorithm for an evolutionary airline network model so as to include network specific control properties. An airline network designer, referred to as a network architect, can use this tool to assess the possibilities of gaining more capacity by changing the network configuration. Since the Airline Deregulation Act of 1978, the airline service network has evolved into a distinct Hub-and-Spoke (H&S) network. Enplanement demand on the H&S network is the sum of Origin-Destination (O-D) demand and transfer demand. Even though the flight or enplanement demand is a function of O-D demand and passenger routings on the airline network, the distinction between enplanement and O-D demand is not often made. Instead, many demand forecast practices in current days are based on scale-ups from the enplanements, which include the demand to and from transferring network hubs. Based on this research, it was found that the current demand prediction practice can be improved by dissecting enplanements further into smaller pieces of information. As a result, enplanement demand is decomposed into intrinsic and variable parts. The proposed intrinsic demand model is based on the concept of 'true' O-D demand which includes the direction of each round trip

  10. Network bipartivity and the transportation efficiency of European passenger airlines

    NASA Astrophysics Data System (ADS)

    Estrada, Ernesto; Gómez-Gardeñes, Jesús

    2016-06-01

    The analysis of the structural organization of the interaction network of a complex system is central to understand its functioning. Here, we focus on the analysis of the bipartivity of graphs. We first introduce a mathematical approach to quantify bipartivity and show its implementation in general and random graphs. Then, we tackle the analysis of the transportation networks of European airlines from the point of view of their bipartivity and observe significant differences between traditional and low cost carriers. Bipartivity shows also that alliances and major mergers of traditional airlines provide a way to reduce bipartivity which, in its turn, is closely related to an increase of the transportation efficiency.

  11. Molecular transport network security using multi-wavelength optical spins.

    PubMed

    Tunsiri, Surachai; Thammawongsa, Nopparat; Mitatha, Somsak; Yupapin, Preecha P

    2016-01-01

    Multi-wavelength generation system using an optical spin within the modified add-drop optical filter known as a PANDA ring resonator for molecular transport network security is proposed. By using the dark-bright soliton pair control, the optical capsules can be constructed and applied to securely transport the trapped molecules within the network. The advantage is that the dark and bright soliton pair (components) can securely propagate for long distance without electromagnetic interference. In operation, the optical intensity from PANDA ring resonator is fed into gold nano-antenna, where the surface plasmon oscillation between soliton pair and metallic waveguide is established. PMID:25058032

  12. A Cultural Algorithm for the Urban Public Transportation

    NASA Astrophysics Data System (ADS)

    Reyes, Laura Cruz; Zezzatti, Carlos Alberto Ochoa Ortíz; Santillán, Claudia Gómez; Hernández, Paula Hernández; Fuerte, Mercedes Villa

    In the last years the population of Leon City, located in the state of Guanajuato in Mexico, has been considerably increasing, causing the inhabitants to waste most of their time with public transportation. As a consequence of the demographic growth and traffic bottleneck, users deal with the daily problem of optimizing their travel so that to get to their destination on time. To give a solution to this problem of obtaining an optimized route between two points in a public transportation, a method based on the cultural algorithms technique is proposed. Cultural algorithms are used in the generated knowledge in a set of time periods for a same population, using a belief space. These types of algorithms are a recent creation. The proposed method seeks a path that minimizes the time of traveling and the number of transfers. The results of the experiment show that the technique of the cultural algorithms is applicable to these kinds of multi-objective problems.

  13. Commuter exposure to aerosol pollution on public transport in Singapore

    NASA Astrophysics Data System (ADS)

    Tan, S.; Velasco, E.; Roth, M.; Norford, L.

    2013-12-01

    Personal exposure to aerosol pollutants in the transport microenvironment of Singapore has not been well documented. Studies from many cities suggest that brief periods of exposure to high concentrations of airborne pollutants may have significant health impacts. Thus, a large proportion of aerosol exposure may be experienced during daily commuting trips due to the proximity to traffic. A better understanding of the variability across transport modes is therefore needed to design transport policies that minimize commuters' exposure. In light of this, personal exposure measurements of PM10 and PM2.5, particle number (PN), black carbon (BC), carbon monoxide (CO), particle-bound polycyclic aromatic hydrocarbons (pPAH), and active surface area (SA) were conducted on a selected route in downtown Singapore. Portable and real-time monitoring instruments were carried onto three different modes of public transport (bus, taxi, subway) and by foot. Simultaneous measurements were taken at a nearby park to capture the background concentrations. Large variability was observed amongst the various transport modes investigated. For example, the particle number concentration was on average 1.5, 1.6, 0.8, and 2.2 times higher inside buses, taxis, subway and by foot, respectively, than at the background site. Based on the results, it is possible to come up with a ranking of the 'cleanest' transport mode for Singapore.

  14. Ride On! Mini-Units and Learning Activities on Public Transportation for Grades 6 through 9.

    ERIC Educational Resources Information Center

    Finn, Peter; And Others

    One of a series of eleven curriculum manuals which cover the four transportation topics of public transportation, transportation and the environment, transportation safety, and bicycles for elementary, secondary, and adult levels, this manual covers the public transportation topic for grades 6-9. It contains forty-two learning activities grouped…

  15. Ride On! Mini-Units and Learning Activities on Public Transportation for Grades 9 through 12.

    ERIC Educational Resources Information Center

    Finn, Peter; And Others

    One of a series of eleven curriculum manuals which cover the four transportation topics of public transportation, transportation and the environment, transportation safety, and bicycles for elementary, secondary, and adult levels, this manual covers the public transportation topic for grades 9-12. It contains forty-nine learning activities grouped…

  16. Correlates of Walking for Transportation and Use of Public Transportation Among Adults in St Louis, Missouri, 2012

    PubMed Central

    Hipp, James A.; Corseuil, Marui W.; Dodson, Elizabeth A.

    2014-01-01

    Introduction Attributes of the built environment can influence active transportation, including use of public transportation. However, the relationship between perceptions of the built environment and use of public transportation deserves further attention. The objectives of this study were 1) to assess the relationship between personal characteristics and public transportation use with meeting national recommendations for moderate physical activity through walking for transportation and 2) to examine associations between personal and perceived environmental factors and frequency of public transportation use. Methods In 2012, we administered a mail-based survey to 772 adults in St Louis, Missouri, to assess perceptions of the built environment, physical activity, and transportation behaviors. The abbreviated International Physical Activity Questionnaire was used to assess walking for transportation and use of public transportation. The Neighborhood Environment Walkability Scale was used to examine perceptions of the built environment. Associations were assessed by using multinomial logistic regression. Results People who used public transportation at least once in the previous week were more likely to meet moderate physical activity recommendations by walking for transportation. Age and employment were significantly associated with public transportation use. Perceptions of high traffic speed and high crime were negatively associated with public transportation use. Conclusion Our results were consistent with previous research suggesting that public transportation use is related to walking for transportation. More importantly, our study suggests that perceptions of traffic speed and crime are related to frequency of public transportation use. Future interventions to encourage public transportation use should consider policy and planning decisions that reduce traffic speed and improve safety. PMID:24995654

  17. T-SDN architecture for space and ground integrated optical transport network

    NASA Astrophysics Data System (ADS)

    Nie, Kunkun; Hu, Wenjing; Gao, Shenghua; Chang, Chengwu

    2015-11-01

    Integrated optical transport network is the development trend of the future space information backbone network. The space and ground integrated optical transport network(SGIOTN) may contain a variety of equipment and systems. Changing the network or meeting some innovation missions in the network will be an expensive implement. Software Defined Network(SDN) provides a good solution to flexibly adding process logic, timely control states and resources of the whole network, as well as shielding the differences of heterogeneous equipment and so on. According to the characteristics of SGIOTN, we propose an transport SDN architecture for it, with hierarchical control plane and data plane composed of packet networks and optical transport networks.

  18. Communicable Disease Case Entry Using PDAs and Public Wireless Networks

    PubMed Central

    Lober, WB; Bliss, D; Dockrey, MR; Davidson, AJ; Karras, BT

    2003-01-01

    Concerns about detecting and responding to attacks with biowarfare agents have resulted in the development of deployable case reporting systems, e.g. RSVP1. We implement a proof of concept web-based information system to be used securely from personal digital assistants over public wireless networks, by public health field workers for routine and emergent case reporting. The system collects data for a local health jurisdiction, provides content- and event-based notification, and forwards case reports to the Colorado State communicable disease reporting system (CEDRS). We believe this demonstrates a useful integration of portable and web-based technologies with public health practice. PMID:14728422

  19. Public Management and Educational Performance: The Impact of Managerial Networking.

    ERIC Educational Resources Information Center

    Meier, Kenneth J.; O'Toole, Laurence J., Jr.

    2003-01-01

    A 5-year performance analysis of managers in more than 500 school districts used a nonlinear, interactive, contingent model of management. Empirical support was found for key elements of the network-management portion of the model. Results showed that public management matters in policy implementation, but its impact is often nonlinear. (Contains…

  20. Reconstructing direct and indirect interactions in networked public goods game

    PubMed Central

    Han, Xiao; Shen, Zhesi; Wang, Wen-Xu; Lai, Ying-Cheng; Grebogi, Celso

    2016-01-01

    Network reconstruction is a fundamental problem for understanding many complex systems with unknown interaction structures. In many complex systems, there are indirect interactions between two individuals without immediate connection but with common neighbors. Despite recent advances in network reconstruction, we continue to lack an approach for reconstructing complex networks with indirect interactions. Here we introduce a two-step strategy to resolve the reconstruction problem, where in the first step, we recover both direct and indirect interactions by employing the Lasso to solve a sparse signal reconstruction problem, and in the second step, we use matrix transformation and optimization to distinguish between direct and indirect interactions. The network structure corresponding to direct interactions can be fully uncovered. We exploit the public goods game occurring on complex networks as a paradigm for characterizing indirect interactions and test our reconstruction approach. We find that high reconstruction accuracy can be achieved for both homogeneous and heterogeneous networks, and a number of empirical networks in spite of insufficient data measurement contaminated by noise. Although a general framework for reconstructing complex networks with arbitrary types of indirect interactions is yet lacking, our approach opens new routes to separate direct and indirect interactions in a representative complex system. PMID:27444774

  1. Reconstructing direct and indirect interactions in networked public goods game

    NASA Astrophysics Data System (ADS)

    Han, Xiao; Shen, Zhesi; Wang, Wen-Xu; Lai, Ying-Cheng; Grebogi, Celso

    2016-07-01

    Network reconstruction is a fundamental problem for understanding many complex systems with unknown interaction structures. In many complex systems, there are indirect interactions between two individuals without immediate connection but with common neighbors. Despite recent advances in network reconstruction, we continue to lack an approach for reconstructing complex networks with indirect interactions. Here we introduce a two-step strategy to resolve the reconstruction problem, where in the first step, we recover both direct and indirect interactions by employing the Lasso to solve a sparse signal reconstruction problem, and in the second step, we use matrix transformation and optimization to distinguish between direct and indirect interactions. The network structure corresponding to direct interactions can be fully uncovered. We exploit the public goods game occurring on complex networks as a paradigm for characterizing indirect interactions and test our reconstruction approach. We find that high reconstruction accuracy can be achieved for both homogeneous and heterogeneous networks, and a number of empirical networks in spite of insufficient data measurement contaminated by noise. Although a general framework for reconstructing complex networks with arbitrary types of indirect interactions is yet lacking, our approach opens new routes to separate direct and indirect interactions in a representative complex system.

  2. Reconstructing direct and indirect interactions in networked public goods game.

    PubMed

    Han, Xiao; Shen, Zhesi; Wang, Wen-Xu; Lai, Ying-Cheng; Grebogi, Celso

    2016-01-01

    Network reconstruction is a fundamental problem for understanding many complex systems with unknown interaction structures. In many complex systems, there are indirect interactions between two individuals without immediate connection but with common neighbors. Despite recent advances in network reconstruction, we continue to lack an approach for reconstructing complex networks with indirect interactions. Here we introduce a two-step strategy to resolve the reconstruction problem, where in the first step, we recover both direct and indirect interactions by employing the Lasso to solve a sparse signal reconstruction problem, and in the second step, we use matrix transformation and optimization to distinguish between direct and indirect interactions. The network structure corresponding to direct interactions can be fully uncovered. We exploit the public goods game occurring on complex networks as a paradigm for characterizing indirect interactions and test our reconstruction approach. We find that high reconstruction accuracy can be achieved for both homogeneous and heterogeneous networks, and a number of empirical networks in spite of insufficient data measurement contaminated by noise. Although a general framework for reconstructing complex networks with arbitrary types of indirect interactions is yet lacking, our approach opens new routes to separate direct and indirect interactions in a representative complex system. PMID:27444774

  3. Public transportation 1995: Current research in planning, management, technology, and ridesharing. Transportation research record

    SciTech Connect

    1995-12-31

    ;Partial Contents: Long-Range Planning Issues for Small Transit Agencies; Methods and Strategies for Transit Benefit Measurement; Relationships Between Public Transport Finance and National Economy in The Netherlands; Modifying Transit Mode Share in Household Survey Expansion; Measuring Impacts of Transit Financing Policy in Geopolitical Context: Montreal Case; Perspective on Maglev Transit and Introduction of Personal Rapid Transit Maglev; Profile of Employee Transportation Coordinators; Demographics of Carpooling; Carpooling with Co-workers in Los Angeles: Employer Involvement Does Make a Difference; Stated Choice-Based Performance Evaluation of Selected Transportation Control Measures and Their Transfer Across Sites; and Five-Year Results of Employee Commute Options in Southern California.

  4. Understanding Charge Transport in Mixed Networks of Semiconducting Carbon Nanotubes

    PubMed Central

    2016-01-01

    The ability to select and enrich semiconducting single-walled carbon nanotubes (SWNT) with high purity has led to a fast rise of solution-processed nanotube network field-effect transistors (FETs) with high carrier mobilities and on/off current ratios. However, it remains an open question whether it is best to use a network of only one nanotube species (monochiral) or whether a mix of purely semiconducting nanotubes but with different bandgaps is sufficient for high performance FETs. For a range of different polymer-sorted semiconducting SWNT networks, we demonstrate that a very small amount of narrow bandgap nanotubes within a dense network of large bandgap nanotubes can dominate the transport and thus severely limit on-currents and effective carrier mobility. Using gate-voltage-dependent electroluminescence, we spatially and spectrally reveal preferential charge transport that does not depend on nominal network density but on the energy level distribution within the network and carrier density. On the basis of these results, we outline rational guidelines for the use of mixed SWNT networks to obtain high performance FETs while reducing the cost for purification. PMID:26867006

  5. Understanding Charge Transport in Mixed Networks of Semiconducting Carbon Nanotubes.

    PubMed

    Rother, Marcel; Schießl, Stefan P; Zakharko, Yuriy; Gannott, Florentina; Zaumseil, Jana

    2016-03-01

    The ability to select and enrich semiconducting single-walled carbon nanotubes (SWNT) with high purity has led to a fast rise of solution-processed nanotube network field-effect transistors (FETs) with high carrier mobilities and on/off current ratios. However, it remains an open question whether it is best to use a network of only one nanotube species (monochiral) or whether a mix of purely semiconducting nanotubes but with different bandgaps is sufficient for high performance FETs. For a range of different polymer-sorted semiconducting SWNT networks, we demonstrate that a very small amount of narrow bandgap nanotubes within a dense network of large bandgap nanotubes can dominate the transport and thus severely limit on-currents and effective carrier mobility. Using gate-voltage-dependent electroluminescence, we spatially and spectrally reveal preferential charge transport that does not depend on nominal network density but on the energy level distribution within the network and carrier density. On the basis of these results, we outline rational guidelines for the use of mixed SWNT networks to obtain high performance FETs while reducing the cost for purification. PMID:26867006

  6. Using Massive Vehicle Positioning Data to Improve Control and Planning of Public Road Transport

    PubMed Central

    Padrón, Gabino; García, Carmelo R.; Quesada-Arencibia, A.; Alayón, Francisco; Pérez, Ricardo

    2014-01-01

    This study describes a system for the automatic recording of positioning data for public transport vehicles used on roads. With the data provided by this system, transportation-regulatory authorities can control, verify and improve the routes that vehicles use, while also providing new data to improve the representation of the transportation network and providing new services in the context of intelligent metropolitan areas. The system is executed autonomously in the vehicles, by recording their massive positioning data and transferring them to remote data banks for subsequent processing. To illustrate the utility of the system, we present a case of application that consists of identifying the points at which vehicles stop systematically, which may be points of scheduled stops or points at which traffic signals or road topology force the vehicle to stop. This identification is performed using pattern recognition techniques. The system has been applied under real operating conditions, providing the results discussed in the present study. PMID:24763212

  7. Enhanced energy transport in genetically engineered excitonic networks.

    PubMed

    Park, Heechul; Heldman, Nimrod; Rebentrost, Patrick; Abbondanza, Luigi; Iagatti, Alessandro; Alessi, Andrea; Patrizi, Barbara; Salvalaggio, Mario; Bussotti, Laura; Mohseni, Masoud; Caruso, Filippo; Johnsen, Hannah C; Fusco, Roberto; Foggi, Paolo; Scudo, Petra F; Lloyd, Seth; Belcher, Angela M

    2016-02-01

    One of the challenges for achieving efficient exciton transport in solar energy conversion systems is precise structural control of the light-harvesting building blocks. Here, we create a tunable material consisting of a connected chromophore network on an ordered biological virus template. Using genetic engineering, we establish a link between the inter-chromophoric distances and emerging transport properties. The combination of spectroscopy measurements and dynamic modelling enables us to elucidate quantum coherent and classical incoherent energy transport at room temperature. Through genetic modifications, we obtain a significant enhancement of exciton diffusion length of about 68% in an intermediate quantum-classical regime. PMID:26461447

  8. Enhanced energy transport in genetically engineered excitonic networks

    NASA Astrophysics Data System (ADS)

    Park, Heechul; Heldman, Nimrod; Rebentrost, Patrick; Abbondanza, Luigi; Iagatti, Alessandro; Alessi, Andrea; Patrizi, Barbara; Salvalaggio, Mario; Bussotti, Laura; Mohseni, Masoud; Caruso, Filippo; Johnsen, Hannah C.; Fusco, Roberto; Foggi, Paolo; Scudo, Petra F.; Lloyd, Seth; Belcher, Angela M.

    2016-02-01

    One of the challenges for achieving efficient exciton transport in solar energy conversion systems is precise structural control of the light-harvesting building blocks. Here, we create a tunable material consisting of a connected chromophore network on an ordered biological virus template. Using genetic engineering, we establish a link between the inter-chromophoric distances and emerging transport properties. The combination of spectroscopy measurements and dynamic modelling enables us to elucidate quantum coherent and classical incoherent energy transport at room temperature. Through genetic modifications, we obtain a significant enhancement of exciton diffusion length of about 68% in an intermediate quantum-classical regime.

  9. The New Hampshire public health network: creating local public health infrastructure through community-driven partnerships.

    PubMed

    Kassler, William J; Goldsberry, Yvonne P

    2005-01-01

    In 1997, under the auspices of the Turning Point program, New Hampshire's public health stakeholders convened a strategic planning process to transform the state public health system. What emerged was a fundamental vision that the public health system could only be improved by strengthening the capacity of local communities to address local health issues. A plan was developed to create regional public health structures, in areas with no local health departments, to deliver essential public health services at the local level. Seven years later, that plan has become the New Hampshire Public Health Network. The network now covers 67% of the New Hampshire population and includes 113 (48%) cities and towns. Pre- and postevaluations to assess local public health infrastructure at the inception of the program and following 2 years of funding and technical assistance showed significant improvement in local public health capacity and performance. This article describes the development of local public health structures in New Hampshire where none had previously existed. PMID:15711445

  10. Active transport and cluster formation on 2D networks.

    PubMed

    Greulich, P; Santen, L

    2010-06-01

    We introduce a model for active transport on inhomogeneous networks embedded in a diffusive environment which is motivated by vesicular transport on actin filaments. In the presence of a hard-core interaction, particle clusters are observed that exhibit an algebraically decaying distribution in a large parameter regime, indicating the existence of clusters on all scales. The scale-free behavior can be understood by a mechanism promoting preferential attachment of particles to large clusters. The results are compared with a diffusion-limited aggregation model and active transport on a regular network. For both models we observe aggregation of particles to clusters which are characterized by a finite size scale if the relevant time scales and particle densities are considered. PMID:20556462

  11. Transportation of a microwave environment over networks and the applications

    NASA Astrophysics Data System (ADS)

    Shoji, Yozo

    2012-01-01

    The concept of the transportation of a microwave environment over networks using a digitized Radio-on-Fibre (DRoF) technique as well as the concept of in-network microwave processing, which could make the concept of "wired and wireless network virtualization" into a reality, is discussed. The new applications to a radio-on-demand service (RoD), software-defined radio-aware network (SDRAN), and microwave environments cloud are introduced. 10-Gbps Ethernet based microwave-to-network interface converter (MiNIC) are developed and the transportation of multiple digital TV broadcasting signals is demonstrated. It is shown that the MiNIC should use more than 8-bits resolution in digitization of a microwave environment when 7 channels of TV signals are included in it. The concept of remote microwave environments observation over networks is demonstrated, where the frequency channel and received signal strength indication (RSSI) of the detected digital TV broadcasting signals are remotely monitored.

  12. 77 FR 43144 - Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-23

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Federal Transit Administration Limitation on Claims Against Proposed Public Transportation Projects AGENCY... claim seeking judicial review of the FTA actions announced herein for the listed public...

  13. 78 FR 26112 - Limitation on Claims Against Proposed Public Transportation Projects; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-03

    ... Federal Transit Administration Limitation on Claims Against Proposed Public Transportation Projects..., concerning a limitation on claims for certain specified public transportation projects. The notice contained... Friday, except Federal holidays. Correction In the Federal Register notice dated April 22, 2013, FR...

  14. 76 FR 35939 - Notice of Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-20

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Federal Transit Administration Notice of Limitation on Claims Against Proposed Public Transportation... that FTA has taken final agency actions by issuing certain approvals for the public...

  15. 76 FR 19522 - Notice of Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-07

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Federal Transit Administration Notice of Limitation on Claims Against Proposed Public Transportation... that FTA has taken final agency actions by issuing certain approvals for the public...

  16. Experimental Study of Heat Transport in Fractured Network

    NASA Astrophysics Data System (ADS)

    Pastore, Nicola; Cherubini, Claudia; Giasi, Concetta I.; Allegretti, Nicoletta M.; Redondo, Jose M.; Tarquis, Ana Maria

    2015-04-01

    Fractured rocks play an important role in transport of natural resources or contaminants transport through subsurface systems. In recent years, interest has grown in investigating heat transport by means of tracer tests, driven by the important current development of geothermal applications. In literature different methods are available for predicting thermal breakthrough in fractured reservoirs based on the information coming from tracer tests. Geothermal energy is one of the largest sources of renewable energies that are extracted from the earth. The growing interest in this new energy source has stimulated attempts to develop methods and technologies for extracting energy also from ground resource at low temperature. An example is the exploitation of low enthalpy geothermal energy that can be obtained at any place with the aid of ground-source heat pump system from the soil, rock and groundwater. In such geothermal systems the fluid movement and thermal behavior in the fractured porous media is very important and critical. Existing theory of fluid flow and heat transport through porous media is of limited usefulness when applied to fractured rocks. Many field and laboratory tracer tests in fractured media show that fracture -matrix exchange is more significant for heat than mass tracers, thus thermal breakthrough curves (BTCs) are strongly controlled by matrix thermal diffusivity. In this study the behaviour of heat transport in a fractured network at bench scale has been investigated. Heat tracer tests on an artificially created fractured rock sample have been carried out. The observed thermal BTCs obtained with six thermocouple probes located at different locations in the fractured medium have been modeled with the Explicit Network Model (ENM) based an adaptation of Tang's solution for solute transport in a semi-infinite single fracture embedded in a porous matrix. The ENM model is able to represent the behavior of observed heat transport except where the

  17. 75 FR 71181 - Notice of Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-22

    ... TRANSPORTATION Federal Transit Administration Notice of Limitation on Claims Against Proposed Public... review of the FTA actions announced herein for the listed public transportation projects will be barred... issuing certain approvals for the public transportation projects listed below. The actions on...

  18. 76 FR 4150 - Notice of Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-24

    ... Federal Transit Administration Notice of Limitation on Claims Against Proposed Public Transportation... judicial review of the FTA actions announced herein for the listed public transportation project will be... final agency actions by issuing certain approvals for the public transportation project listed...

  19. 76 FR 72746 - Notice of Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-25

    ... Federal Transit Administration Notice of Limitation on Claims Against Proposed Public Transportation... judicial review of the FTA actions announced herein for the listed public transportation project will be... final agency actions by issuing certain approvals for the public transportation projects listed...

  20. 75 FR 27114 - Public Transportation on Indian Reservations Program; Tribal Transit Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-13

    ... Federal Transit Administration Public Transportation on Indian Reservations Program; Tribal Transit... availability of $15,074,963 million in funding provided by the Public Transportation on Indian Reservations.... Overview Section 3013 of SAFETEA-LU, amended 49 U.S.C. 5311(c) by establishing the Public Transportation...

  1. 76 FR 2950 - Notice of Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-18

    ... TRANSPORTATION Federal Transit Administration Notice of Limitation on Claims Against Proposed Public... announced herein for the listed public transportation projects will be barred unless the claim is filed on... approvals for the public transportation projects listed below. The actions on these projects, as well as...

  2. 77 FR 76597 - Limitation on Claims against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-28

    ... Federal Transit Administration Limitation on Claims against Proposed Public Transportation Projects AGENCY... for the listed public transportation project will be barred unless the claim is filed on or before May... approvals for the public transportation project listed below. The actions on this project, as well as...

  3. 78 FR 33890 - Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-05

    ... Federal Transit Administration Limitation on Claims Against Proposed Public Transportation Projects AGENCY... review of the FTA actions announced herein for the listed public transportation project will be barred... taken final agency actions by issuing certain approvals for the public transportation projects...

  4. 78 FR 65756 - Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-01

    ... Federal Transit Administration Limitation on Claims Against Proposed Public Transportation Projects AGENCY... herein for the listed public transportation project will be barred unless the claim is filed on or before... approvals for the public transportation project listed below. The actions on the project, as well as...

  5. 76 FR 55470 - Notice of Limitation on Claims Against Proposed Public Transportation Project

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-07

    ... Federal Transit Administration Notice of Limitation on Claims Against Proposed Public Transportation... public transportation project will be barred unless the claim is filed on or before March 5, 2012. FOR... FTA has taken final agency action by issuing certain approvals for the public transportation...

  6. 78 FR 16764 - Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-18

    ... Federal Transit Administration Limitation on Claims Against Proposed Public Transportation Projects AGENCY... review of the FTA actions announced herein for the listed public transportation project will be barred... taken final agency actions by issuing certain approvals for the public transportation project...

  7. 77 FR 26818 - Notice of Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-07

    ... Federal Transit Administration Notice of Limitation on Claims Against Proposed Public Transportation... review of the FTA actions announced herein for the listed public transportation project will be barred... FTA has taken final agency actions by issuing certain approvals for the public transportation...

  8. 76 FR 25773 - Notice of Limitation on Claims Against Proposed Public Transportation Project

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-05

    ... Federal Transit Administration Notice of Limitation on Claims Against Proposed Public Transportation... announced herein for the listed public transportation project will be barred unless the claim is filed on or... approvals for the public transportation project listed below. The actions on this project, as well as...

  9. 77 FR 14465 - Public Transportation on Indian Reservations Program; Tribal Transit Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-09

    ... Federal Transit Administration Public Transportation on Indian Reservations Program; Tribal Transit... Surface and Air Transportation Programs Extension Act of 2011, Public Law No.112-30 continues the... establishing the Public Transportation on Indian Reservations Program (Tribal Transit Program or TTP)....

  10. 78 FR 53001 - Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-27

    ... Federal Transit Administration Limitation on Claims Against Proposed Public Transportation Projects AGENCY... public transportation project will be barred unless the claim is filed on or before January 24, 2014. FOR... the public transportation projects listed below. The actions on the projects, as well as the...

  11. 78 FR 4191 - Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-18

    ... Federal Transit Administration Limitation on Claims Against Proposed Public Transportation Projects AGENCY... review of the FTA actions announced herein for the listed public transportation project will be barred... final agency actions by issuing certain approvals for the public transportation projects listed...

  12. 78 FR 32296 - Second Allocation of Public Transportation Emergency Relief Funds in Response to Hurricane Sandy...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-29

    ... Federal Transit Administration Second Allocation of Public Transportation Emergency Relief Funds in... Administration (FTA) announces the allocation of $3.7 billion under the Public Transportation Emergency Relief... costs after an emergency or major disaster that affects public transportation systems. The...

  13. 78 FR 45287 - Limitation on Claims against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-26

    ... Federal Transit Administration Limitation on Claims against Proposed Public Transportation Projects AGENCY... herein for the listed public transportation project will be barred unless the claim is filed on or before... approval for the public transportation project listed below. The action on the project, as well as the...

  14. 75 FR 13335 - Notice of Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-19

    ... Federal Transit Administration Notice of Limitation on Claims Against Proposed Public Transportation... herein for the listed public transportation projects will be barred unless the claim is filed on or... issuing certain approvals for the public transportation projects listed below. The actions on...

  15. 77 FR 34122 - Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-08

    ... Federal Transit Administration Limitation on Claims Against Proposed Public Transportation Projects AGENCY... actions announced herein for the listed public transportation project will be barred unless the claim is... actions by issuing certain approvals for the public transportation project listed below. The actions...

  16. 77 FR 64586 - Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-22

    ... Federal Transit Administration Limitation on Claims Against Proposed Public Transportation Projects AGENCY... public transportation project will be barred unless the claim is filed on or before March 21, 2013. FOR... the public transportation projects listed below. The actions on these projects, as well as the...

  17. 76 FR 621 - Commercial Space Transportation Advisory Committee-Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-05

    ... Federal Aviation Administration Commercial Space Transportation Advisory Committee--Public Teleconference AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of Commercial Space Transportation... Space Transportation Advisory Committee (COMSTAC). The teleconference will take place on...

  18. 77 FR 44707 - Commercial Space Transportation Advisory Committee-Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-30

    ... Federal Aviation Administration Commercial Space Transportation Advisory Committee--Public Teleconference AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of Commercial Space Transportation... Working Group of the Commercial Space Transportation Advisory Committee (COMSTAC). The...

  19. 76 FR 12211 - Commercial Space Transportation Advisory Committee-Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-04

    ... Federal Aviation Administration Commercial Space Transportation Advisory Committee--Public Teleconference AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of Commercial Space Transportation... Commercial Space Transportation Advisory Committee (COMSTAC). The teleconference will take place on...

  20. 76 FR 4988 - Commercial Space Transportation Advisory Committee-Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-27

    ... Federal Aviation Administration Commercial Space Transportation Advisory Committee--Public Teleconference AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of Commercial Space Transportation... Space Transportation Advisory Committee (COMSTAC). The teleconference will take place on...

  1. 76 FR 41323 - Commercial Space Transportation Advisory Committee-Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-13

    ... Federal Aviation Administration Commercial Space Transportation Advisory Committee--Public Teleconference AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of Commercial Space Transportation... Space Transportation Advisory Committee (COMSTAC). The teleconference will take place on...

  2. 76 FR 42160 - Commercial Space Transportation Advisory Committee-Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-18

    ... Federal Aviation Administration Commercial Space Transportation Advisory Committee--Public Teleconference AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of Space Transportation Operations Working Group of the Commercial Space Transportation Advisory Committee Teleconference. SUMMARY:...

  3. 77 FR 65443 - Commercial Space Transportation Advisory Committee-Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-26

    ... Federal Aviation Administration Commercial Space Transportation Advisory Committee--Public Teleconference AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of Commercial Space Transportation... Working Group of the Commercial Space Transportation Advisory Committee (COMSTAC). The...

  4. 77 FR 48585 - Commercial Space Transportation Advisory Committee-Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-14

    ... Federal Aviation Administration Commercial Space Transportation Advisory Committee--Public Teleconference AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of Commercial Space Transportation... Working Group (OWG) of the Commercial Space Transportation Advisory Committee (COMSTAC)....

  5. 78 FR 1917 - Commercial Space Transportation Advisory Committee-Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-09

    ... TRANSPORTATION Federal Aviation Administration Commercial Space Transportation Advisory Committee--Public Teleconference AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of Commercial Space... Space Transportation Advisory Committee (COMSTAC). DATES: The teleconference will take place on...

  6. Optimal transport in time-varying small-world networks

    NASA Astrophysics Data System (ADS)

    Chen, Qu; Qian, Jiang-Hai; Zhu, Liang; Han, Ding-Ding

    2016-03-01

    The time-order of interactions, which is regulated by some intrinsic activity, surely plays a crucial role regarding the transport efficiency of transportation systems. Here we study the optimal transport structure by measure of the length of time-respecting paths. Our network is built from a two-dimensional regular lattice, and long-range connections are allocated with probability Pi j˜rij -α , where ri j is the Manhattan distance. By assigning each shortcut an activity rate subjected to its geometric distance τi j˜rij -C , long-range links become active intermittently, leading to the time-varying dynamics. We show that for 0 network behaves as a small world with an optimal structural exponent αopt that slightly grows with C as αopt˜log(C ) , while for C ≫2 the αopt→∞ . The unique restriction between C and α unveils an optimization principle in time-varying transportation networks. Empirical studies on British Airways and Austrian Airlines provide consistent evidence with our conclusion.

  7. Enhancing coherent transport in a photonic network using controllable decoherence

    NASA Astrophysics Data System (ADS)

    Biggerstaff, Devon N.; Heilmann, René; Zecevik, Aidan A.; Gräfe, Markus; Broome, Matthew A.; Fedrizzi, Alessandro; Nolte, Stefan; Szameit, Alexander; White, Andrew G.; Kassal, Ivan

    2016-04-01

    Transport phenomena on a quantum scale appear in a variety of systems, ranging from photosynthetic complexes to engineered quantum devices. It has been predicted that the efficiency of coherent transport can be enhanced through dynamic interaction between the system and a noisy environment. We report an experimental simulation of environment-assisted coherent transport, using an engineered network of laser-written waveguides, with relative energies and inter-waveguide couplings tailored to yield the desired Hamiltonian. Controllable-strength decoherence is simulated by broadening the bandwidth of the input illumination, yielding a significant increase in transport efficiency relative to the narrowband case. We show integrated optics to be suitable for simulating specific target Hamiltonians as well as open quantum systems with controllable loss and decoherence.

  8. Enhancing coherent transport in a photonic network using controllable decoherence.

    PubMed

    Biggerstaff, Devon N; Heilmann, René; Zecevik, Aidan A; Gräfe, Markus; Broome, Matthew A; Fedrizzi, Alessandro; Nolte, Stefan; Szameit, Alexander; White, Andrew G; Kassal, Ivan

    2016-01-01

    Transport phenomena on a quantum scale appear in a variety of systems, ranging from photosynthetic complexes to engineered quantum devices. It has been predicted that the efficiency of coherent transport can be enhanced through dynamic interaction between the system and a noisy environment. We report an experimental simulation of environment-assisted coherent transport, using an engineered network of laser-written waveguides, with relative energies and inter-waveguide couplings tailored to yield the desired Hamiltonian. Controllable-strength decoherence is simulated by broadening the bandwidth of the input illumination, yielding a significant increase in transport efficiency relative to the narrowband case. We show integrated optics to be suitable for simulating specific target Hamiltonians as well as open quantum systems with controllable loss and decoherence. PMID:27080915

  9. Enhancing coherent transport in a photonic network using controllable decoherence

    PubMed Central

    Biggerstaff, Devon N.; Heilmann, René; Zecevik, Aidan A.; Gräfe, Markus; Broome, Matthew A.; Fedrizzi, Alessandro; Nolte, Stefan; Szameit, Alexander; White, Andrew G.; Kassal, Ivan

    2016-01-01

    Transport phenomena on a quantum scale appear in a variety of systems, ranging from photosynthetic complexes to engineered quantum devices. It has been predicted that the efficiency of coherent transport can be enhanced through dynamic interaction between the system and a noisy environment. We report an experimental simulation of environment-assisted coherent transport, using an engineered network of laser-written waveguides, with relative energies and inter-waveguide couplings tailored to yield the desired Hamiltonian. Controllable-strength decoherence is simulated by broadening the bandwidth of the input illumination, yielding a significant increase in transport efficiency relative to the narrowband case. We show integrated optics to be suitable for simulating specific target Hamiltonians as well as open quantum systems with controllable loss and decoherence. PMID:27080915

  10. Active patterning and asymmetric transport in a model actomyosin network

    NASA Astrophysics Data System (ADS)

    Wang, Shenshen; Wolynes, Peter G.

    2013-12-01

    Cytoskeletal networks, which are essentially motor-filament assemblies, play a major role in many developmental processes involving structural remodeling and shape changes. These are achieved by nonequilibrium self-organization processes that generate functional patterns and drive intracellular transport. We construct a minimal physical model that incorporates the coupling between nonlinear elastic responses of individual filaments and force-dependent motor action. By performing stochastic simulations we show that the interplay of motor processes, described as driving anti-correlated motion of the network vertices, and the network connectivity, which determines the percolation character of the structure, can indeed capture the dynamical and structural cooperativity which gives rise to diverse patterns observed experimentally. The buckling instability of individual filaments is found to play a key role in localizing collapse events due to local force imbalance. Motor-driven buckling-induced node aggregation provides a dynamic mechanism that stabilizes the two-dimensional patterns below the apparent static percolation limit. Coordinated motor action is also shown to suppress random thermal noise on large time scales, the two-dimensional configuration that the system starts with thus remaining planar during the structural development. By carrying out similar simulations on a three-dimensional anchored network, we find that the myosin-driven isotropic contraction of a well-connected actin network, when combined with mechanical anchoring that confers directionality to the collective motion, may represent a novel mechanism of intracellular transport, as revealed by chromosome translocation in the starfish oocyte.

  11. Active patterning and asymmetric transport in a model actomyosin network

    SciTech Connect

    Wang, Shenshen; Wolynes, Peter G.

    2013-12-21

    Cytoskeletal networks, which are essentially motor-filament assemblies, play a major role in many developmental processes involving structural remodeling and shape changes. These are achieved by nonequilibrium self-organization processes that generate functional patterns and drive intracellular transport. We construct a minimal physical model that incorporates the coupling between nonlinear elastic responses of individual filaments and force-dependent motor action. By performing stochastic simulations we show that the interplay of motor processes, described as driving anti-correlated motion of the network vertices, and the network connectivity, which determines the percolation character of the structure, can indeed capture the dynamical and structural cooperativity which gives rise to diverse patterns observed experimentally. The buckling instability of individual filaments is found to play a key role in localizing collapse events due to local force imbalance. Motor-driven buckling-induced node aggregation provides a dynamic mechanism that stabilizes the two-dimensional patterns below the apparent static percolation limit. Coordinated motor action is also shown to suppress random thermal noise on large time scales, the two-dimensional configuration that the system starts with thus remaining planar during the structural development. By carrying out similar simulations on a three-dimensional anchored network, we find that the myosin-driven isotropic contraction of a well-connected actin network, when combined with mechanical anchoring that confers directionality to the collective motion, may represent a novel mechanism of intracellular transport, as revealed by chromosome translocation in the starfish oocyte.

  12. Linear network representation of multistate models of transport.

    PubMed

    Sandblom, J; Ring, A; Eisenman, G

    1982-05-01

    By introducing external driving forces in rate-theory models of transport we show how the Eyring rate equations can be transformed into Ohm's law with potentials that obey Kirchhoff's second law. From such a formalism the state diagram of a multioccupancy multicomponent system can be directly converted into linear network with resistors connecting nodal (branch) points and with capacitances connecting each nodal point with a reference point. The external forces appear as emf or current generators in the network. This theory allows the algebraic methods of linear network theory to be used in solving the flux equations for multistate models and is particularly useful for making proper simplifying approximation in models of complex membrane structure. Some general properties of linear network representation are also deduced. It is shown, for instance, that Maxwell's reciprocity relationships of linear networks lead directly to Onsager's relationships in the near equilibrium region. Finally, as an example of the procedure, the equivalent circuit method is used to solve the equations for a few transport models. PMID:7093425

  13. Locating inefficient links in a large-scale transportation network

    NASA Astrophysics Data System (ADS)

    Sun, Li; Liu, Like; Xu, Zhongzhi; Jie, Yang; Wei, Dong; Wang, Pu

    2015-02-01

    Based on data from geographical information system (GIS) and daily commuting origin destination (OD) matrices, we estimated the distribution of traffic flow in the San Francisco road network and studied Braess's paradox in a large-scale transportation network with realistic travel demand. We measured the variation of total travel time Δ T when a road segment is closed, and found that | Δ T | follows a power-law distribution if Δ T < 0 or Δ T > 0. This implies that most roads have a negligible effect on the efficiency of the road network, while the failure of a few crucial links would result in severe travel delays, and closure of a few inefficient links would counter-intuitively reduce travel costs considerably. Generating three theoretical networks, we discovered that the heterogeneously distributed travel demand may be the origin of the observed power-law distributions of | Δ T | . Finally, a genetic algorithm was used to pinpoint inefficient link clusters in the road network. We found that closing specific road clusters would further improve the transportation efficiency.

  14. Alert Distribution Network And Public Data Of The SVOM Mission

    SciTech Connect

    Claret, A.

    2008-05-22

    SVOM (Space-based multi-band astronomical Variable Objects Monitor) has been designed to detect all known types of gamma-ray bursts (GRBs), to provide fast and reliable GRB positions, to measure the broadband spectral shape and temporal properties of the GRB prompt emission, and to quickly identify the optical afterglows, including those which are highly redshifted. In this paper, we focus on the alert distribution network and the public data which will be available to the GRB community.

  15. An Organic Anion Transporter 1 (OAT1)-centered Metabolic Network.

    PubMed

    Liu, Henry C; Jamshidi, Neema; Chen, Yuchen; Eraly, Satish A; Cho, Sai Yee; Bhatnagar, Vibha; Wu, Wei; Bush, Kevin T; Abagyan, Ruben; Palsson, Bernhard O; Nigam, Sanjay K

    2016-09-01

    There has been a recent interest in the broader physiological importance of multispecific "drug" transporters of the SLC and ABC transporter families. Here, a novel multi-tiered systems biology approach was used to predict metabolites and signaling molecules potentially affected by the in vivo deletion of organic anion transporter 1 (Oat1, Slc22a6, originally NKT), a major kidney-expressed drug transporter. Validation of some predictions in wet-lab assays, together with re-evaluation of existing transport and knock-out metabolomics data, generated an experimentally validated, confidence ranked set of OAT1-interacting endogenous compounds enabling construction of an "OAT1-centered metabolic interaction network." Pathway and enrichment analysis indicated an important role for OAT1 in metabolism involving: the TCA cycle, tryptophan and other amino acids, fatty acids, prostaglandins, cyclic nucleotides, odorants, polyamines, and vitamins. The partly validated reconstructed network is also consistent with a major role for OAT1 in modulating metabolic and signaling pathways involving uric acid, gut microbiome products, and so-called uremic toxins accumulating in chronic kidney disease. Together, the findings are compatible with the hypothesized role of drug transporters in remote inter-organ and inter-organismal communication: The Remote Sensing and Signaling Hypothesis (Nigam, S. K. (2015) Nat. Rev. Drug Disc. 14, 29). The fact that OAT1 can affect many systemic biological pathways suggests that drug-metabolite interactions need to be considered beyond simple competition for the drug transporter itself and may explain aspects of drug-induced metabolic syndrome. Our approach should provide novel mechanistic insights into the role of OAT1 and other drug transporters implicated in metabolic diseases like gout, diabetes, and chronic kidney disease. PMID:27440044

  16. Statistical theory of designed quantum transport across disordered networks.

    PubMed

    Walschaers, Mattia; Mulet, Roberto; Wellens, Thomas; Buchleitner, Andreas

    2015-04-01

    We explain how centrosymmetry, together with a dominant doublet of energy eigenstates in the local density of states, can guarantee interference-assisted, strongly enhanced, strictly coherent quantum excitation transport between two predefined sites of a random network of two-level systems. Starting from a generalization of the chaos-assisted tunnelling mechanism, we formulate a random matrix theoretical framework for the analytical prediction of the transfer time distribution, of lower bounds of the transfer efficiency, and of the scaling behavior of characteristic statistical properties with the size of the network. We show that these analytical predictions compare well to numerical simulations, using Hamiltonians sampled from the Gaussian orthogonal ensemble. PMID:25974468

  17. Statistical theory of designed quantum transport across disordered networks

    NASA Astrophysics Data System (ADS)

    Walschaers, Mattia; Mulet, Roberto; Wellens, Thomas; Buchleitner, Andreas

    2015-04-01

    We explain how centrosymmetry, together with a dominant doublet of energy eigenstates in the local density of states, can guarantee interference-assisted, strongly enhanced, strictly coherent quantum excitation transport between two predefined sites of a random network of two-level systems. Starting from a generalization of the chaos-assisted tunnelling mechanism, we formulate a random matrix theoretical framework for the analytical prediction of the transfer time distribution, of lower bounds of the transfer efficiency, and of the scaling behavior of characteristic statistical properties with the size of the network. We show that these analytical predictions compare well to numerical simulations, using Hamiltonians sampled from the Gaussian orthogonal ensemble.

  18. Why do Scale-Free Networks Emerge in Nature? From Gradient Networks to Transport Efficiency

    NASA Astrophysics Data System (ADS)

    Toroczkai, Zoltan

    2004-03-01

    It has recently been recognized [1,2,3] that a large number of complex networks are scale-free (having a power-law degree distribution). Examples include citation networks [4], the internet [5], the world-wide-web [6], cellular metabolic networks [7], protein interaction networks [8], the sex-web [9] and alliance networks in the U.S. biotechnology industry [10]. The existence of scale-free networks in such diverse systems suggests that there is a simple underlying common reason for their development. Here, we propose that scale-free networks emerge because they ensure efficient transport of some entity. We show that for flows generated by gradients of a scalar "potential'' distributed on a network, non scale-free networks, e.g., random graphs [11], will become maximally congested, while scale-free networks will ensure efficient transport in the large network size limit. [1] R. Albert and A.-L. Barabási, Rev.Mod.Phys. 74, 47 (2002). [2] M.E.J. Newman, SIAM Rev. 45, 167 (2003). [3] S.N. Dorogovtsev and J.F.F. Mendes, Evolution of Networks: From Biological Nets to the Internet and WWW, Oxford Univ. Press, Oxford, 2003. [4] S. Redner, Eur.Phys.J. B, 4, 131 (1998). [5] M. Faloutsos, P. Faloutsos and C. Faloutsos Comp.Comm.Rev. 29, 251 (1999). [6] R. Albert, H. Jeong, and A.L. Barabási, Nature 401, 130 (1999). [7] H. Jeong et.al. Nature 407, 651 (2000). [8] H. Jeong, S. Mason, A.-L. Barabási and Z. N. Oltvai, Nature 411, 41 (2001). [9] F. Liljeros et. al. Nature 411 907 (2000). [10] W. W. Powell, D. R. White, K. W. Koput and J. Owen-Smith Am.J.Soc. in press. [11] B. Bollobás, Random Graphs, Second Edition, Cambridge University Press (2001).

  19. 36 CFR 5.9 - Discrimination in furnishing public accommodations and transportation services.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Discrimination in furnishing public accommodations and transportation services. 5.9 Section 5.9 Parks, Forests, and Public Property... furnishing public accommodations and transportation services. (a) The proprietor, owner or operator and...

  20. 36 CFR 5.9 - Discrimination in furnishing public accommodations and transportation services.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Discrimination in furnishing public accommodations and transportation services. 5.9 Section 5.9 Parks, Forests, and Public Property... furnishing public accommodations and transportation services. (a) The proprietor, owner or operator and...

  1. 36 CFR 1005.9 - Discrimination in furnishing public accommodations and transportation services.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Discrimination in furnishing public accommodations and transportation services. 1005.9 Section 1005.9 Parks, Forests, and Public Property PRESIDIO TRUST COMMERCIAL AND PRIVATE OPERATIONS § 1005.9 Discrimination in furnishing public accommodations and transportation services....

  2. 36 CFR 5.9 - Discrimination in furnishing public accommodations and transportation services.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Discrimination in furnishing public accommodations and transportation services. 5.9 Section 5.9 Parks, Forests, and Public Property... furnishing public accommodations and transportation services. (a) The proprietor, owner or operator and...

  3. 36 CFR 5.9 - Discrimination in furnishing public accommodations and transportation services.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Discrimination in furnishing public accommodations and transportation services. 5.9 Section 5.9 Parks, Forests, and Public Property... furnishing public accommodations and transportation services. (a) The proprietor, owner or operator and...

  4. Service-Transport Separated Network Architecture Using MPLS-TP Technologies

    NASA Astrophysics Data System (ADS)

    Sakamoto, Kenichi; Ashi, Yoshihiro; Takase, Akihiko

    We propose a next-generation service-transport separated network architecture that uses packet technology. The transport network is responsible for the high speed and reliable bit transfer, and the service network is responsible for many types of network services. This separation makes it possible for the next-generation network to achieve both rapid bandwidth spreading and the speedy installation of new services. We also propose a next-generation transport network using the multi-protocol label switching transport profile (MPLS-TP) and optical networking technologies.

  5. Electronic transport in phosphorus-doped silicon nanocrystal networks.

    PubMed

    Stegner, A R; Pereira, R N; Klein, K; Lechner, R; Dietmueller, R; Brandt, M S; Stutzmann, M; Wiggers, H

    2008-01-18

    We have investigated the role of doping and paramagnetic states on the electronic transport of networks assembled from freestanding Si nanocrystals (Si-NCs). Electrically detected magnetic resonance (EDMR) studies on Si-NCs films, which show a strong increase of conductivity with doping of individual Si-NCs, reveal that P donors and Si dangling bonds contribute to dark conductivity via spin-dependent hopping, whereas in photoconductivity, these states act as spin-dependent recombination centers of photogenerated electrons and holes. Comparison between EDMR and conventional electron paramagnetic resonance shows that different subsets of P-doped nanocrystals contribute to the different transport processes. PMID:18232904

  6. Transportation and dynamic networks: Models, theory, and applications to supply chains, electric power, and financial networks

    NASA Astrophysics Data System (ADS)

    Liu, Zugang

    Network systems, including transportation and logistic systems, electric power generation and distribution networks as well as financial networks, provide the critical infrastructure for the functioning of our societies and economies. The understanding of the dynamic behavior of such systems is also crucial to national security and prosperity. The identification of new connections between distinct network systems is the inspiration for the research in this dissertation. In particular, I answer two questions raised by Beckmann, McGuire, and Winsten (1956) and Copeland (1952) over half a century ago, which are, respectively, how are electric power flows related to transportation flows and does money flow like water or electricity? In addition, in this dissertation, I achieve the following: (1) I establish the relationships between transportation networks and three other classes of complex network systems: supply chain networks, electric power generation and transmission networks, and financial networks with intermediation. The establishment of such connections provides novel theoretical insights as well as new pricing mechanisms, and efficient computational methods. (2) I develop new modeling frameworks based on evolutionary variational inequality theory that capture the dynamics of such network systems in terms of the time-varying flows and incurred costs, prices, and, where applicable, profits. This dissertation studies the dynamics of such network systems by addressing both internal competition and/or cooperation, and external changes, such as varying costs and demands. (3) I focus, in depth, on electric power supply chains. By exploiting the relationships between transportation networks and electric power supply chains, I develop a large-scale network model that integrates electric power supply chains and fuel supply markets. The model captures both the economic transactions as well as the physical transmission constraints. The model is then applied to the New

  7. Cooperating Mobile GIS and Wireless Sensor Networks for Managing Transportation Infrastructures in Urban areas

    NASA Astrophysics Data System (ADS)

    Shad, R.; Abazari, N.; Alizadeh, A.; Choghooni, M.

    2013-10-01

    Time management is a major subject which, in order to optimize trip conditions, emphasizes on interpreting processes and classifying individual's information. In this paper, with the aim of providing an optimal system for urban commuting in proper time in Mashhad, each user using SMS and introducing some of his/her mental priorities to the system, will be able to select the best option depending on the timing of movement of the available public transport system. The present study adopts a newly developed method of time management which is evaluated for urban transportation considering dynamic conditions of a spatial database. For this purpose, regarding time management, processed data such as bus lines, taxi networks, and the subway system are combined in a spatial framework of a designed Mobile GIS based on a wireless network. So, multiple potential paths which end to a desirable destination.

  8. Empirical investigation of topological and weighted properties of a bus transport network from China

    NASA Astrophysics Data System (ADS)

    Shu-Min, Feng; Bao-Yu, Hu; Cen, Nie; Xiang-Hao, Shen; Yu-Sheng, Ci

    2016-03-01

    Many bus transport networks (BTNs) have evolved into directed networks. A new representation model for BTNs is proposed, called directed-space P. The bus transport network of Harbin (BTN-H) is described as a directed and weighted complex network by the proposed representation model and by giving each node weights. The topological and weighted properties are revealed in detail. In-degree and out-degree distributions, in-weight and out-weight distributions are presented as an exponential law, respectively. There is a strong relation between in-weight and in-degree (also between out-weight and out-degree), which can be fitted by a power function. Degree-degree and weight-weight correlations are investigated to reveal that BTN-H has a disassortative behavior as the nodes have relatively high degree (or weight). The disparity distributions of out-degree and in-degree follow an approximate power-law. Besides, the node degree shows a near linear increase with the number of routes that connect to the corresponding station. These properties revealed in this paper can help public transport planners to analyze the status quo of the BTN in nature. Project supported by the National High Technology Research and Development Program of China (Grant No. 2014AA110304).

  9. Architecture of a framework for providing information services for public transport.

    PubMed

    García, Carmelo R; Pérez, Ricardo; Lorenzo, Alvaro; Quesada-Arencibia, Alexis; Alayón, Francisco; Padrón, Gabino

    2012-01-01

    This paper presents OnRoute, a framework for developing and running ubiquitous software that provides information services to passengers of public transportation, including payment systems and on-route guidance services. To achieve a high level of interoperability, accessibility and context awareness, OnRoute uses the ubiquitous computing paradigm. To guarantee the quality of the software produced, the reliable software principles used in critical contexts, such as automotive systems, are also considered by the framework. The main components of its architecture (run-time, system services, software components and development discipline) and how they are deployed in the transportation network (stations and vehicles) are described in this paper. Finally, to illustrate the use of OnRoute, the development of a guidance service for travellers is explained. PMID:22778585

  10. Architecture of a Framework for Providing Information Services for Public Transport

    PubMed Central

    García, Carmelo R.; Pérez, Ricardo; Lorenzo, Álvaro; Quesada-Arencibia, Alexis; Alayón, Francisco; Padrón, Gabino

    2012-01-01

    This paper presents OnRoute, a framework for developing and running ubiquitous software that provides information services to passengers of public transportation, including payment systems and on-route guidance services. To achieve a high level of interoperability, accessibility and context awareness, OnRoute uses the ubiquitous computing paradigm. To guarantee the quality of the software produced, the reliable software principles used in critical contexts, such as automotive systems, are also considered by the framework. The main components of its architecture (run-time, system services, software components and development discipline) and how they are deployed in the transportation network (stations and vehicles) are described in this paper. Finally, to illustrate the use of OnRoute, the development of a guidance service for travellers is explained. PMID:22778585

  11. Transport pathways within percolating pore space networks of granular materials

    NASA Astrophysics Data System (ADS)

    Vo, Kevin; Walker, David M.; Tordesillas, Antoinette

    2013-06-01

    Granular media can be regarded as a mixture of two components: grains and the material filling the voids or pores between the grains. Pore properties give rise to a range of applications such as modelling ground water flow, carbon capture and sequestration. The grains within a dense granular material respond to deformation (e.g., shearing or compression) by rearranging to create local zones of compression and zones of dilatation (i.e., regions of high pore space). Descriptions of the deformation are typically focused on analysis of the solid skeleton via topology of physical contact networks of grains but an alternative perspective is to consider network representations of the evolving anisotropic pore space. We demonstrate how to construct pore space networks that express the local size of voids about a grain through network edge weights. We investigate sectors of the loading history when a percolating giant component of the pore space network exists. At these states the grains are in a configuration more prone to the efficient transport of material (e.g., fluid flow, mineral/gas deposits). These pathways can be found through examination of the weighted shortest paths percolating the boundaries of the material. In particular, network weights biased towards large void space results in efficient percolating pathways traversing the shear band in the direction of principal stress within a 2D granular assembly subject to high strains.

  12. 47 CFR 51.325 - Notice of network changes: Public notice requirement.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false Notice of network changes: Public notice... § 51.325 Notice of network changes: Public notice requirement. (a) An incumbent local exchange carrier (“LEC”) must provide public notice regarding any network change that: (1) Will affect a...

  13. 47 CFR 51.325 - Notice of network changes: Public notice requirement.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 3 2011-10-01 2011-10-01 false Notice of network changes: Public notice... § 51.325 Notice of network changes: Public notice requirement. (a) An incumbent local exchange carrier (“LEC”) must provide public notice regarding any network change that: (1) Will affect a...

  14. 76 FR 51271 - Implementing a Nationwide, Broadband, Interoperable Public Safety Network in the 700 MHz Band

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-18

    ... COMMISSION 47 CFR Part 90 Implementing a Nationwide, Broadband, Interoperable Public Safety Network in the... interoperable public safety broadband network. The establishment of a common air interface for 700 MHz public safety broadband networks will create a foundation for interoperability and provide a clear path for...

  15. 47 CFR 51.325 - Notice of network changes: Public notice requirement.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 3 2012-10-01 2012-10-01 false Notice of network changes: Public notice... § 51.325 Notice of network changes: Public notice requirement. (a) An incumbent local exchange carrier (“LEC”) must provide public notice regarding any network change that: (1) Will affect a...

  16. 47 CFR 51.325 - Notice of network changes: Public notice requirement.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 3 2014-10-01 2014-10-01 false Notice of network changes: Public notice... § 51.325 Notice of network changes: Public notice requirement. (a) An incumbent local exchange carrier (“LEC”) must provide public notice regarding any network change that: (1) Will affect a...

  17. 47 CFR 51.325 - Notice of network changes: Public notice requirement.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 3 2013-10-01 2013-10-01 false Notice of network changes: Public notice... § 51.325 Notice of network changes: Public notice requirement. (a) An incumbent local exchange carrier (“LEC”) must provide public notice regarding any network change that: (1) Will affect a...

  18. An artificial neural network controller for intelligent transportation systems applications

    SciTech Connect

    Vitela, J.E.; Hanebutte, U.R.; Reifman, J.

    1996-04-01

    An Autonomous Intelligent Cruise Control (AICC) has been designed using a feedforward artificial neural network, as an example for utilizing artificial neural networks for nonlinear control problems arising in intelligent transportation systems applications. The AICC is based on a simple nonlinear model of the vehicle dynamics. A Neural Network Controller (NNC) code developed at Argonne National Laboratory to control discrete dynamical systems was used for this purpose. In order to test the NNC, an AICC-simulator containing graphical displays was developed for a system of two vehicles driving in a single lane. Two simulation cases are shown, one involving a lead vehicle with constant velocity and the other a lead vehicle with varying acceleration. More realistic vehicle dynamic models will be considered in future work.

  19. Radionuclide gas transport through nuclear explosion-generated fracture networks

    SciTech Connect

    Jordan, Amy B.; Stauffer, Philip H.; Knight, Earl E.; Rougier, Esteban; Anderson, Dale N.

    2015-12-17

    Underground nuclear weapon testing produces radionuclide gases which may seep to the surface. Barometric pumping of gas through explosion-fractured rock is investigated using a new sequentially-coupled hydrodynamic rock damage/gas transport model. Fracture networks are produced for two rock types (granite and tuff) and three depths of burial. The fracture networks are integrated into a flow and transport numerical model driven by surface pressure signals of differing amplitude and variability. There are major differences between predictions using a realistic fracture network and prior results that used a simplified geometry. Matrix porosity and maximum fracture aperture have the greatest impact on gas breakthrough time and window of opportunity for detection, with different effects between granite and tuff simulations highlighting the importance of accurately simulating the fracture network. In particular, maximum fracture aperture has an opposite effect on tuff and granite, due to different damage patterns and their effect on the barometric pumping process. From stochastic simulations using randomly generated hydrogeologic parameters, normalized detection curves are presented to show differences in optimal sampling time for granite and tuff simulations. In conclusion, seasonal and location-based effects on breakthrough, which occur due to differences in barometric forcing, are stronger where the barometric signal is highly variable.

  20. Radionuclide Gas Transport through Nuclear Explosion-Generated Fracture Networks

    PubMed Central

    Jordan, Amy B.; Stauffer, Philip H.; Knight, Earl E.; Rougier, Esteban; Anderson, Dale N.

    2015-01-01

    Underground nuclear weapon testing produces radionuclide gases which may seep to the surface. Barometric pumping of gas through explosion-fractured rock is investigated using a new sequentially-coupled hydrodynamic rock damage/gas transport model. Fracture networks are produced for two rock types (granite and tuff) and three depths of burial. The fracture networks are integrated into a flow and transport numerical model driven by surface pressure signals of differing amplitude and variability. There are major differences between predictions using a realistic fracture network and prior results that used a simplified geometry. Matrix porosity and maximum fracture aperture have the greatest impact on gas breakthrough time and window of opportunity for detection, with different effects between granite and tuff simulations highlighting the importance of accurately simulating the fracture network. In particular, maximum fracture aperture has an opposite effect on tuff and granite, due to different damage patterns and their effect on the barometric pumping process. From stochastic simulations using randomly generated hydrogeologic parameters, normalized detection curves are presented to show differences in optimal sampling time for granite and tuff simulations. Seasonal and location-based effects on breakthrough, which occur due to differences in barometric forcing, are stronger where the barometric signal is highly variable. PMID:26676058

  1. Radionuclide Gas Transport through Nuclear Explosion-Generated Fracture Networks.

    PubMed

    Jordan, Amy B; Stauffer, Philip H; Knight, Earl E; Rougier, Esteban; Anderson, Dale N

    2015-01-01

    Underground nuclear weapon testing produces radionuclide gases which may seep to the surface. Barometric pumping of gas through explosion-fractured rock is investigated using a new sequentially-coupled hydrodynamic rock damage/gas transport model. Fracture networks are produced for two rock types (granite and tuff) and three depths of burial. The fracture networks are integrated into a flow and transport numerical model driven by surface pressure signals of differing amplitude and variability. There are major differences between predictions using a realistic fracture network and prior results that used a simplified geometry. Matrix porosity and maximum fracture aperture have the greatest impact on gas breakthrough time and window of opportunity for detection, with different effects between granite and tuff simulations highlighting the importance of accurately simulating the fracture network. In particular, maximum fracture aperture has an opposite effect on tuff and granite, due to different damage patterns and their effect on the barometric pumping process. From stochastic simulations using randomly generated hydrogeologic parameters, normalized detection curves are presented to show differences in optimal sampling time for granite and tuff simulations. Seasonal and location-based effects on breakthrough, which occur due to differences in barometric forcing, are stronger where the barometric signal is highly variable. PMID:26676058

  2. Radionuclide gas transport through nuclear explosion-generated fracture networks

    DOE PAGESBeta

    Jordan, Amy B.; Stauffer, Philip H.; Knight, Earl E.; Rougier, Esteban; Anderson, Dale N.

    2015-12-17

    Underground nuclear weapon testing produces radionuclide gases which may seep to the surface. Barometric pumping of gas through explosion-fractured rock is investigated using a new sequentially-coupled hydrodynamic rock damage/gas transport model. Fracture networks are produced for two rock types (granite and tuff) and three depths of burial. The fracture networks are integrated into a flow and transport numerical model driven by surface pressure signals of differing amplitude and variability. There are major differences between predictions using a realistic fracture network and prior results that used a simplified geometry. Matrix porosity and maximum fracture aperture have the greatest impact on gasmore » breakthrough time and window of opportunity for detection, with different effects between granite and tuff simulations highlighting the importance of accurately simulating the fracture network. In particular, maximum fracture aperture has an opposite effect on tuff and granite, due to different damage patterns and their effect on the barometric pumping process. From stochastic simulations using randomly generated hydrogeologic parameters, normalized detection curves are presented to show differences in optimal sampling time for granite and tuff simulations. In conclusion, seasonal and location-based effects on breakthrough, which occur due to differences in barometric forcing, are stronger where the barometric signal is highly variable.« less

  3. Radionuclide Gas Transport through Nuclear Explosion-Generated Fracture Networks

    NASA Astrophysics Data System (ADS)

    Jordan, Amy B.; Stauffer, Philip H.; Knight, Earl E.; Rougier, Esteban; Anderson, Dale N.

    2015-12-01

    Underground nuclear weapon testing produces radionuclide gases which may seep to the surface. Barometric pumping of gas through explosion-fractured rock is investigated using a new sequentially-coupled hydrodynamic rock damage/gas transport model. Fracture networks are produced for two rock types (granite and tuff) and three depths of burial. The fracture networks are integrated into a flow and transport numerical model driven by surface pressure signals of differing amplitude and variability. There are major differences between predictions using a realistic fracture network and prior results that used a simplified geometry. Matrix porosity and maximum fracture aperture have the greatest impact on gas breakthrough time and window of opportunity for detection, with different effects between granite and tuff simulations highlighting the importance of accurately simulating the fracture network. In particular, maximum fracture aperture has an opposite effect on tuff and granite, due to different damage patterns and their effect on the barometric pumping process. From stochastic simulations using randomly generated hydrogeologic parameters, normalized detection curves are presented to show differences in optimal sampling time for granite and tuff simulations. Seasonal and location-based effects on breakthrough, which occur due to differences in barometric forcing, are stronger where the barometric signal is highly variable.

  4. AllAboard: Visual Exploration of Cellphone Mobility Data to Optimise Public Transport.

    PubMed

    Di Lorenzo, G; Sbodio, M; Calabrese, F; Berlingerio, M; Pinelli, F; Nair, R

    2016-02-01

    The deep penetration of mobile phones offers cities the ability to opportunistically monitor citizens' mobility and use data-driven insights to better plan and manage services. With large scale data on mobility patterns, operators can move away from the costly, mostly survey based, transportation planning processes, to a more data-centric view, that places the instrumented user at the center of development. In this framework, using mobile phone data to perform transit analysis and optimization represents a new frontier with significant societal impact, especially in developing countries. In this paper we present AllAboard, an intelligent tool that analyses cellphone data to help city authorities in visually exploring urban mobility and optimizing public transport. This is performed within a self contained tool, as opposed to the current solutions which rely on a combination of several distinct tools for analysis, reporting, optimisation and planning. An interactive user interface allows transit operators to visually explore the travel demand in both space and time, correlate it with the transit network, and evaluate the quality of service that a transit network provides to the citizens at very fine grain. Operators can visually test scenarios for transit network improvements, and compare the expected impact on the travellers' experience. The system has been tested using real telecommunication data for the city of Abidjan, Ivory Coast, and evaluated from a data mining, optimisation and user prospective. PMID:26731450

  5. Modelling and evaluation of optical WDM transport networks

    NASA Astrophysics Data System (ADS)

    Wauters, Nico

    1997-10-01

    In this PhD thesis optical WDM transport networks are investigated that use novel optical components to transmit simultaneously multiple datasignals using WDM and which route in their nodes incoming datasignals to one of the outlet fibers without converting these signals to the electrical domain. The goal of the thesis is twofold. On the one hand developing new models that lead to a classification of components, nodes, network architectures and network management techniques such as monitoring and signalling. On the other hand to investigate to which extent wavelength convertors are required for an optimal use of the available wavelength channels. At the same time the tuneability of the WDM terminal multiplexers is questioned. Part 1 gives a general introduction to optical transmission and network techniques by an extensive study of the literature and a limited market survey. In part 2 we propose a number of new models to represent WDM networks and their main building blocks. This leads to a black box model and a classification of all the OXC architectures. Secondly we extend the G.803 layer structure with new layers allowing the representation of hybrid WDM and SDH networks. Finally the model is used to classify different signalling and monitoring options that can be followed. In part 3 we investigate the requirement of wavelength convertors and the tuneability of the WDM terminal multiplexers. The main conclusion of this part is that wavelength translation is not a conditio sine qua non to achieve low blocking probabilities. This contrasts to the much larger difference that appeared between WPa and WPb and which allowed us to conclude that tuneability of the WDM terminal multiplexers is thoroughly required. We do not want to disregard other consequences of not using wavelength convertors in the network as e.g., simplified wavelength management in networks with wavelength convertors and the regeneration capabilities of new all- optical wavelength conversion devices.

  6. How to assess extreme weather impacts - case European transport network

    NASA Astrophysics Data System (ADS)

    Leviäkangas, P.

    2010-09-01

    To assess the impacts of climate change and preparing for impacts is a process. This process we must understand and learn to apply. EWENT (Extreme Weather impacts on European Networks of Transport) will be a test bench for one prospective approach. It has the following main components: 1) identifying what is "extreme", 2) assessing the change in the probabilities, 3) constructing the causal impact models, 4) finding appropriate methods of pricing and costing, 5) finding alternative strategy option, 6) assessing the efficiency of strategy option. This process follows actually the steps of standardized risk management process. Each step is challenging, but if EWENT project succeeds to assess the extreme weather impacts on European transport networks, it is one possible benchmark how to carry out similar analyses in other regions and on country level. EWENT approach could particularly useful for weather and climate information service providers, offering tools for transport authorities and financiers to assess weather risks, and then rationally managing the risks. EWENT project is financed by the European Commission and participated by met-service organisations and transport research institutes from different parts of Europe. The presentation will explain EWENT approach in detail and bring forth the findings of the first work packages.

  7. Soil organic carbon, macropore networks and preferential transport

    NASA Astrophysics Data System (ADS)

    Larsbo, Mats; Koestel, John; Kätterer, Thomas; Jarvis, Nick

    2016-04-01

    Agricultural management practices such as tillage, crop rotations, residue management and fertilization can have a strong influence on soil organic carbon (SOC) stocks. An increase in SOC content will generally improve soil structure, which in turn determines the solute transport pathways through the soil. The aim of this study was to quantify the architecture of macropore networks in undisturbed soil columns (15 cm high, 12.7 cm diameter) sampled along a transect with natural variations in SOC using X-ray tomography and to relate the network characteristics to the degree of preferential transport in the columns. Two tracer experiments were carried out at constant irrigation rates of 2 and 5 mm h-1. We used the normalised 5% arrival time which reflects the tendency for early arrival of the solutes as a measure of the degree of preferential transport. The soil macropore networks were analysed in cylindrical sub-volumes (8 cm high, 10 cm diameter) located centrally within the soil columns. These sub-volumes were considered unaffected by sampling artefacts. Analyses were also carried out the for whole sample volumes to enable comparisons with the results from the transport experiments. Image processing and analysis were carried out in ImageJ and R. The same grey value threshold was applied to all images after harmonisation of grey values using the PVC column walls and the air outside the columns. This approach resulted in a satisfactory separation between the pore space and the surrounding soil matrix and organic matter. The SOC content along the transect, which varied from 4.2 to 15% , was correlated to all measures of the pore network for the sub-volumes except for the connectivity probability. Columns with high SOC content were associated with large macroporosities (both total and connected), large specific surface areas, large fractal dimensions and small mean pore thicknesses. The SOC content for whole sample volumes was positively correlated to 5% arrival times

  8. Severe Weather Case Studies from the USArray Transportable Array Network

    NASA Astrophysics Data System (ADS)

    Tytell, J. E.; Vernon, F. L.; Busby, R. W.; Eakins, J. A.; Hedlin, M. A.; Muschinski, A.; Walker, K. T.; Woodward, R.

    2011-12-01

    Earthscope's USArray Transportable Array (TA) network serves as a real-time monitoring and recording platform for both seismic and weather phenomena. To date, most of the approximately 500 TA stations have been retrofitted with VTI SCP1000 MEMS barometric pressure gauges capable of recording data at 1 sample per second (sps). Additionally, over 100 of the TA stations have also been retrofitted with Setra 278 barometric gauges and NCPA infrasound sensors capable of recording data at 1 and 40 sps. While individual seismic events have been successfully researched via the TA network, observations of powerful weather events by the TA network have yet to be embraced by the scientific community. This presentation will focus on case studies involving severe weather passage across portions of the TA network throughout 2011 in order to highlight its viability as a platform for real-time weather monitoring and research. Examples of gust front passages and pressure couplets from severe thunderstorms will be presented, as will observations of the devastating tornado that passed through Joplin, Missouri on May 22nd with an enhanced Fujita (EF) strength of EF5. These data will demonstrate the overall viability of the TA network for monitoring severe weather events in real-time.

  9. Exploiting Publication Contents and Collaboration Networks for Collaborator Recommendation

    PubMed Central

    Kong, Xiangjie; Jiang, Huizhen; Yang, Zhuo; Xu, Zhenzhen; Xia, Feng; Tolba, Amr

    2016-01-01

    Thanks to the proliferation of online social networks, it has become conventional for researchers to communicate and collaborate with each other. Meanwhile, one critical challenge arises, that is, how to find the most relevant and potential collaborators for each researcher? In this work, we propose a novel collaborator recommendation model called CCRec, which combines the information on researchers’ publications and collaboration network to generate better recommendation. In order to effectively identify the most potential collaborators for researchers, we adopt a topic clustering model to identify the academic domains, as well as a random walk model to compute researchers’ feature vectors. Using DBLP datasets, we conduct benchmarking experiments to examine the performance of CCRec. The experimental results show that CCRec outperforms other state-of-the-art methods in terms of precision, recall and F1 score. PMID:26849682

  10. Flow and Transport Phenomena in Two-Dimensional Fracture Networks.

    NASA Astrophysics Data System (ADS)

    Rodriguez, Adolfo Antonio

    1995-01-01

    This dissertation presents a comprehensive study of two-dimensional fracture networks; it addresses three different aspects: geometry, fluid-flow and diffusion solute transport. The first subject consists in the description of the topological structure of the network. This is done by creating matrix representations for different topological operators which are then used to describe the geometry of the system. A series of systematic procedures were developed to determine the most important geometrical features of the fracture network including connectivity and backbone. The second point of study was subdivided in two parts: steady-state and transient phenomena. The steady -state hydraulic response of the network was investigated by generalizing the topological formulations of electrical networks. These formulations (which were originally developed by classical authors like Kirchhoff and Weyl) give a convenient mean for expressing the mass balance condition at the nodes. The analogy between electrical conduction and steady-state fluid flow is not exact thus, some additional concepts need to be introduced (like the node-rate-injection vector). Results for this part of the work include detailed vector field diagrams that represent the flow pattern across the network. In order to solve the transient fluid-flow problem, some additional considerations needed to be made. The idea is to start with the one-dimensional partial differential equation that governs the transient fluid flow across a single fracture (diffusion equation). The Laplace transform is then applied to eliminate time, the mass balance condition at each node is expressed in terms of the Laplace transform variables. Once the results are found, the inverse Laplace transforms were obtained via a numerical algorithm (Stephest algorithm). With the introduction of two new topological operators (closely related to the boundary operator), it was possible to express the linear set of mass balance equations in a form