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Sample records for public transport networks

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

    NASA Astrophysics Data System (ADS)

    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.

  2. 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

  3. The Scaling of Several Public Transport Networks in China

    NASA Astrophysics Data System (ADS)

    Guo, Long; Zhu, Yueying; Luo, Zhongjie; Li, Wei

    2013-06-01

    Public transport networks (PTNs) are often researched without reference to their geographical embedding. The question arises if there is any underlying structure or principle characterizing the observed behavior of geographically embedded transport routes. Here, we focus on the scaling properties of PTNs in Space L through fractal analysis and consider the effect of the real bus routes, which reflects the human movement between stations indirectly. We find that the PTN in Space L is the better basal one to mimic the human migration in city. Furthermore, we also research the scaling property of the correlation between stations and the distribution of node's weight, which shows the heterogeneous property of human activity between different stations. Our present work provides some new perspective and tools to realize the human migration on spatial networks.

  4. Performance Analysis of Public Transport Systems in Nanjing Based on Network Topology

    NASA Astrophysics Data System (ADS)

    Li, Ping; Zhu, Zhen-Tao; Zhou, Jing; Ding, Jin-Yuan; Wang, Hong-Wei; Wei, Shan-Sen

    The urban public transport network (UPTN) in Nanjing is characterized by a complex network with topological pedestals. The empirical data indicates that it is a small-world network. Under malicious attack to the high connectivity nodes of the network, the average path-length will increase 2.5 times, the reliability and traffic capacity of the UPTN will greatly decline, and the travel expenditure will distinctively increase. The topological significance of stations and routes are redefined to help assess the small-world property of UPTNs, so as to improve city transportation. It is also found that if the urban rail transit, such as metro, is introduced to the UPTN, then the topological diameter of the network is reduced, and its structure is optimized.

  5. 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

  6. 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.

  7. Urban public transport today

    SciTech Connect

    Simpson, B. )

    1994-01-01

    It is widely recognized that there are many people for whom public transport is essential, particularly among the elderly, children and teenagers. Less obvious is the dependence of our cities for their existence on high capacity public transport. Although there is still a prevalent view that local public transport is only for those who do not have a car, we are slowly beginning to realize that we need to find ways of restricting use of the private car more severely and that will involve some transfer to public transport. Urban Public Transport Today gives an honest appraisal of the pros and cons of new public transport technologies. It shows how public transport can be made a less unacceptable alternative to the private car than it is now.

  8. Transportation and public health.

    PubMed

    Litman, Todd

    2013-01-01

    This article investigates various ways that transportation policy and planning decisions affect public health and better ways to incorporate public health objectives into transport planning. Conventional planning tends to consider some public health impacts, such as crash risk and pollution emissions measured per vehicle-kilometer, but generally ignores health problems resulting from less active transport (reduced walking and cycling activity) and the additional crashes and pollution caused by increased vehicle mileage. As a result, transport agencies tend to undervalue strategies that increase transport system diversity and reduce vehicle travel. This article identifies various win-win strategies that can help improve public health and other planning objectives.

  9. 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

  10. 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

  11. 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

  12. 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

  13. Energy 101: Sustainable Public Transportation

    ScienceCinema

    None

    2016-09-20

    You may already know that public transportation reduces pollution and eases congestion on the road. However, many transit fleets are switching over to cleaner, alternative fuels and technologies, making this mode of transportation even more sustainable.

  14. Energy 101: Sustainable Public Transportation

    SciTech Connect

    2016-09-07

    You may already know that public transportation reduces pollution and eases congestion on the road. However, many transit fleets are switching over to cleaner, alternative fuels and technologies, making this mode of transportation even more sustainable.

  15. 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.

  16. 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.

  17. Heuristic Optimization Approach to Selecting a Transport Connection in City Public Transport

    NASA Astrophysics Data System (ADS)

    Kul'ka, Jozef; Mantič, Martin; Kopas, Melichar; Faltinová, Eva; Kachman, Daniel

    2017-02-01

    The article presents a heuristic optimization approach to select a suitable transport connection in the framework of a city public transport. This methodology was applied on a part of the public transport in Košice, because it is the second largest city in the Slovak Republic and its network of the public transport creates a complex transport system, which consists of three different transport modes, namely from the bus transport, tram transport and trolley-bus transport. This solution focused on examining the individual transport services and their interconnection in relevant interchange points.

  18. Visualizing Mobility of Public Transportation System.

    PubMed

    Zeng, Wei; Fu, Chi-Wing; Arisona, Stefan Müller; Erath, Alexander; Qu, Huamin

    2014-12-01

    Public transportation systems (PTSs) play an important role in modern cities, providing shared/massive transportation services that are essential for the general public. However, due to their increasing complexity, designing effective methods to visualize and explore PTS is highly challenging. Most existing techniques employ network visualization methods and focus on showing the network topology across stops while ignoring various mobility-related factors such as riding time, transfer time, waiting time, and round-the-clock patterns. This work aims to visualize and explore passenger mobility in a PTS with a family of analytical tasks based on inputs from transportation researchers. After exploring different design alternatives, we come up with an integrated solution with three visualization modules: isochrone map view for geographical information, isotime flow map view for effective temporal information comparison and manipulation, and OD-pair journey view for detailed visual analysis of mobility factors along routes between specific origin-destination pairs. The isotime flow map linearizes a flow map into a parallel isoline representation, maximizing the visualization of mobility information along the horizontal time axis while presenting clear and smooth pathways from origin to destinations. Moreover, we devise several interactive visual query methods for users to easily explore the dynamics of PTS mobility over space and time. Lastly, we also construct a PTS mobility model from millions of real passenger trajectories, and evaluate our visualization techniques with assorted case studies with the transportation researchers.

  19. 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

  20. 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…

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

    PubMed

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

    2016-07-16

    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.

  2. 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

  3. 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.

  4. 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…

  5. 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.…

  6. Anomalous Transport in Complex Networks

    NASA Astrophysics Data System (ADS)

    Lopez, Eduardo; Buldyrev, Sergey; Havlin, Shlomo; Stanley, H. Eugene

    2005-03-01

    To study transport properties of complex networks, we analyze the equivalent conductance G between two arbitrarily chosen nodes of random scale-free networks with degree distribution P(k)˜k^-λ in which each link has the same unit resistance. We predict a broad range of values of G, with a power-law tail distribution φSF(G)˜G^-gG, where gG=2λ-1, and confirm our predictions by simulations. The power-law tail in φSF(G) leads to large values of G, thereby significantly improving the transport in scale-free networks, compared to Erdos-R'enyi random graphs where the tail of the conductivity distribution decays exponentially. Based on a simple physical ``transport backbone'' picture we show that the conductances are well approximated by ckAkB/(kA+kB) for any pair of nodes A and B with degrees kA and kB. Thus, a single parameter c characterizes transport on scale-free networks.

  7. 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).

  8. 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.

  9. 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.

  10. Charge transport network dynamics in molecular aggregates

    SciTech Connect

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

    2016-07-20

    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, bBDT(TDPP)2. Simulations reveal the relevant timescale for local transfer integral decorrelation to be ~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.

  11. Charge transport network dynamics in molecular aggregates

    PubMed Central

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

    2016-01-01

    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, bBDT(TDPP)2. Simulations reveal the relevant timescale for local transfer integral decorrelation to be ∼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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. The perils of public transport.

    PubMed

    Atenstaedt, R L

    2007-01-01

    Section 33 of The Public Health (Control of Disease) Act 1984 makes it an offence for a person in England and Wales who is suffering from a notifiable disease, e.g. cholera, to use any bus, tram or train; or use a taxi without notifying the driver or owner of the vehicle, or their carer to allow them to do so. Section 34 of the same act prohibits the owner, driver or conductor of a bus, train or tram from carrying a person who he knows is suffering from one of these diseases However, a taxi can carry an affected person, provided this individual pays a sum in addition to the fare to cover the costs of disinfection. Assuming that the owner or driver did not know that a passenger was suffering from one of these diseases, he must inform the local authority, which is required to disinfect the taxi for free. A literature review using PubMed did not reveal any evidence that buses, trains, trams or taxis provide a significant vehicle for transmission of notifiable diseases. Is it therefore about time that a non-evidence-based and little-used law is removed from the British statute books?

  17. 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

  18. 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.

  19. 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

  20. Dynamical properties of transportation on complex networks

    NASA Astrophysics Data System (ADS)

    Shen, Bo; Gao, Zi-You

    2008-02-01

    We study the dynamical properties of transportation considering the topology structure of networks and congestion effects, based on a proposed simple model. We analyze the behavior of the model for finding out the relationship between the properties of transportation and the structure of network. Analysis and numerical results demonstrate that the transition from free flow to congested regime can be observed for both single link load and network load, but it is discontinuous for single link and continuous for network. We also find that networks with large average degree have small average link betweenness and are more tolerant to congestion, and networks with homogeneous structure can hold more vehicles in stationary state at the subcritical region. Furthermore, by allotting capacity with different mode to links, a manner of enhancing the performance of networks is introduced, which should be helpful in the design of traffic networks.

  1. 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…

  2. Public Libraries and the Network Idea

    ERIC Educational Resources Information Center

    Clapp, Verner W.

    1970-01-01

    Edited version of an address delivered at Institute on Public Library Management (12th, Madison, Wisconsin, April 26, 1968). The library network has not developed because the public has not recognized its potential usefulness. It can provide a new level of service if the value is not nullified by bureaucratic rigidity. (JS)

  3. 28 CFR 36.310 - Transportation provided by public accommodations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... public accommodation, customer shuttle bus services operated by private companies and shopping centers, student transportation systems, and transportation provided within recreational facilities such as... readily achievable. (c) Requirements for vehicles and systems. A public accommodation subject to...

  4. 28 CFR 36.310 - Transportation provided by public accommodations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... public accommodation, customer shuttle bus services operated by private companies and shopping centers, student transportation systems, and transportation provided within recreational facilities such as... readily achievable. (c) Requirements for vehicles and systems. A public accommodation subject to...

  5. 28 CFR 36.310 - Transportation provided by public accommodations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... public accommodation, customer shuttle bus services operated by private companies and shopping centers, student transportation systems, and transportation provided within recreational facilities such as... readily achievable. (c) Requirements for vehicles and systems. A public accommodation subject to...

  6. 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.

  7. Transportation dynamics on networks of mobile agents.

    PubMed

    Yang, Han-Xin; Wang, Wen-Xu; Xie, Yan-Bo; Lai, Ying-Cheng; Wang, Bing-Hong

    2011-01-01

    Most existing works on transportation dynamics focus on networks of a fixed structure, but networks whose nodes are mobile have become widespread, such as cell-phone networks. We introduce a model to explore the basic physics of transportation on mobile networks. Of particular interest is the dependence of the throughput on the speed of agent movement and the communication range. Our computations reveal a hierarchical dependence for the former, while an algebraic power law is found between the throughput and the communication range with the exponent determined by the speed. We develop a physical theory based on the Fokker-Planck equation to explain these phenomena. Our findings provide insights into complex transportation dynamics arising commonly in natural and engineering systems.

  8. Transportation dynamics on networks of mobile agents

    NASA Astrophysics Data System (ADS)

    Yang, Han-Xin; Wang, Wen-Xu; Xie, Yan-Bo; Lai, Ying-Cheng; Wang, Bing-Hong

    2011-01-01

    Most existing works on transportation dynamics focus on networks of a fixed structure, but networks whose nodes are mobile have become widespread, such as cell-phone networks. We introduce a model to explore the basic physics of transportation on mobile networks. Of particular interest is the dependence of the throughput on the speed of agent movement and the communication range. Our computations reveal a hierarchical dependence for the former, while an algebraic power law is found between the throughput and the communication range with the exponent determined by the speed. We develop a physical theory based on the Fokker-Planck equation to explain these phenomena. Our findings provide insights into complex transportation dynamics arising commonly in natural and engineering systems.

  9. 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

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

    PubMed

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

    2014-12-05

    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.

  11. 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.

  12. Anomalous Transport in Scale-Free Networks

    NASA Astrophysics Data System (ADS)

    López, Eduardo; Buldyrev, Sergey V.; Havlin, Shlomo; Stanley, H. Eugene

    2005-06-01

    To study transport properties of scale-free and Erdős-Rényi networks, we analyze the conductance G between two arbitrarily chosen nodes of random scale-free networks with degree distribution P(k)˜k-λ in which all links have unit resistance. We predict a broad range of values of G, with a power-law tail distribution ΦSF(G)˜G-gG, where gG=2λ-1, and confirm our predictions by simulations. The power-law tail in ΦSF(G) leads to large values of G, signaling better transport in scale-free networks compared to Erdős-Rényi networks where the tail of the conductivity distribution decays exponentially. Based on a simple physical “transport backbone” picture we show that the conductances of scale-free and Erdős-Rényi networks are well approximated by ckAkB/(kA+kB) for any pair of nodes A and B with degrees kA and kB, where c emerges as the main parameter characterizing network transport.

  13. 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...

  14. Fluctuations and Redundancy in Optimal Transport Networks

    NASA Astrophysics Data System (ADS)

    Corson, Francis

    2010-01-01

    The structure of networks that provide optimal transport properties has been investigated in a variety of contexts. While many different formulations of this problem have been considered, it is recurrently found that optimal networks are trees. It is shown here that this result is contingent on the assumption of a stationary flow through the network. When time variations or fluctuations are allowed for, a different class of optimal structures is found, which share the hierarchical organization of trees yet contain loops. The transitions between different network topologies as the parameters of the problem vary are examined. These results may have strong implications for the structure and formation of natural networks, as is illustrated by the example of leaf venation networks.

  15. Demand and Congestion in Multiplex Transportation Networks.

    PubMed

    Chodrow, Philip S; Al-Awwad, Zeyad; Jiang, Shan; González, Marta C

    Urban transportation systems are multimodal, sociotechnical systems; however, while their multimodal aspect has received extensive attention in recent literature on multiplex networks, their sociotechnical aspect has been largely neglected. We present the first study of an urban transportation system using multiplex network analysis and validated Origin-Destination travel demand, with Riyadh's planned metro as a case study. We develop methods for analyzing the impact of additional transportation layers on existing dynamics, and show that demand structure plays key quantitative and qualitative roles. There exist fundamental geometrical limits to the metro's impact on traffic dynamics, and the bulk of environmental accrue at metro speeds only slightly faster than those planned. We develop a simple model for informing the use of additional, "feeder" layers to maximize reductions in global congestion. Our techniques are computationally practical, easily extensible to arbitrary transportation layers with complex transfer logic, and implementable in open-source software.

  16. Demand and Congestion in Multiplex Transportation Networks

    PubMed Central

    al-Awwad, Zeyad; Jiang, Shan; González, Marta C.

    2016-01-01

    Urban transportation systems are multimodal, sociotechnical systems; however, while their multimodal aspect has received extensive attention in recent literature on multiplex networks, their sociotechnical aspect has been largely neglected. We present the first study of an urban transportation system using multiplex network analysis and validated Origin-Destination travel demand, with Riyadh’s planned metro as a case study. We develop methods for analyzing the impact of additional transportation layers on existing dynamics, and show that demand structure plays key quantitative and qualitative roles. There exist fundamental geometrical limits to the metro’s impact on traffic dynamics, and the bulk of environmental accrue at metro speeds only slightly faster than those planned. We develop a simple model for informing the use of additional, “feeder” layers to maximize reductions in global congestion. Our techniques are computationally practical, easily extensible to arbitrary transportation layers with complex transfer logic, and implementable in open-source software. PMID:27657738

  17. 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.

  18. Knowledge networks for global public health.

    PubMed

    Natividad, Maria Dulce F; Fiereck, Kirk J; Parker, Richard

    2012-01-01

    The challenges posed by a globalised world have made it imperative for society to search for solutions to emerging issues and to develop new ways of looking at old problems. Current discussions about global public health demand a shift in paradigms and the strategic positioning of public health within broader policy discussions that will enable it to influence political and action agendas. Critical to responding to these challenges is the generation, transmission and dissemination of new knowledge to create value. Recognising the cutting-edge role of knowledge, as a new form of capital that drives innovation and transforms society, the formation of knowledge networks is viewed as a strategy for developing a shared intellectual, conceptual and ethical infrastructure for the field of global public health. These knowledge networks are envisioned as a vehicle for sharing diverse perspectives, encouraging debate and sustaining alternative ways of thinking about and responding to the challenges that confront global public health today and in the future.

  19. 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

  20. Progress in photonic transport network systems

    NASA Astrophysics Data System (ADS)

    Sato, Ken-Ichi

    2002-07-01

    The network paradigm is changing rapidly spurred by the dramatic increase in IP traffic and recent progress in photonic network technologies. A key requirement, enhancing the performance of existing IP-based multimedia communication networks, can be most effectively achieved by introducing optical path technologies that exploit wavelength routing. Cost effective and reliable optical cross-connection is essential. Different optical switch technologies have been proposed and tested. Among them, the PLC (Planer Lightwave Circuit) switch has demonstrated excellent performance, particularly with regard to system reliability. Network control mechanisms based on the overlay and peer model models have been developed. The presentation will highlight some of the key system technologies. To develop very large scale and robust networks, effective traffic engineering capabilities are necessary. This will be achieved through optical path control. To develop future IP-centric networks, an operation mechanism based on distributed control is important. The degree to which the necessary transport and IP routing functions are integrated will determine system cost-effectiveness. The Photonic MPLS (Multi Protocol Label Switching) router, which integrates all the functions and provides seamless operation between IP and optical layers, has been proposed and developed. The technical feasibility of a recent prototype system has been proven. Finally, some of the cutting-edge photonic transport technologies that we have recently developed are demonstrated; these technologies will enable us to achieve another level of network performance enhancement in the future.

  1. Optimally designed quantum transport across disordered networks.

    PubMed

    Walschaers, Mattia; Diaz, Jorge Fernandez-de-Cossio; Mulet, Roberto; Buchleitner, Andreas

    2013-11-01

    We establish a general mechanism for highly efficient quantum transport through finite, disordered 3D networks. It relies on the interplay of disorder with centrosymmetry and a dominant doublet spectral structure and can be controlled by the proper tuning of only coarse-grained quantities. Photosynthetic light harvesting complexes are discussed as potential biological incarnations of this design principle.

  2. 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

  3. Feedback network models for quantum transport

    NASA Astrophysics Data System (ADS)

    Gough, John

    2014-12-01

    Quantum feedback networks have been introduced in quantum optics as a framework for constructing arbitrary networks of quantum mechanical systems connected by unidirectional quantum optical fields, and has allowed for a system theoretic approach to open quantum optics systems. Our aim here is to establish a network theory for quantum transport systems where typically the mediating fields between systems are bidirectional. Mathematically, this leads us to study quantum feedback networks where fields arrive at ports in input-output pairs, making it a special case of the unidirectional theory where inputs and outputs are paired. However, it is conceptually important to develop this theory in the context of quantum transport theory—the resulting theory extends traditional approaches which tend to view the components in quantum transport as scatterers for the various fields, in the process allowing us to consider emission and absorption of field quanta by these components. The quantum feedback network theory is applicable to both Bose and Fermi fields, moreover, it applies to nonlinear dynamics for the component systems. We advance the general theory, but study the case of linear passive quantum components in some detail.

  4. Feedback network models for quantum transport.

    PubMed

    Gough, John

    2014-12-01

    Quantum feedback networks have been introduced in quantum optics as a framework for constructing arbitrary networks of quantum mechanical systems connected by unidirectional quantum optical fields, and has allowed for a system theoretic approach to open quantum optics systems. Our aim here is to establish a network theory for quantum transport systems where typically the mediating fields between systems are bidirectional. Mathematically, this leads us to study quantum feedback networks where fields arrive at ports in input-output pairs, making it a special case of the unidirectional theory where inputs and outputs are paired. However, it is conceptually important to develop this theory in the context of quantum transport theory-the resulting theory extends traditional approaches which tend to view the components in quantum transport as scatterers for the various fields, in the process allowing us to consider emission and absorption of field quanta by these components. The quantum feedback network theory is applicable to both Bose and Fermi fields, moreover, it applies to nonlinear dynamics for the component systems. We advance the general theory, but study the case of linear passive quantum components in some detail.

  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. 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.

  8. 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.

  9. 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

  10. 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.

  11. Population-weighted efficiency in transportation networks.

    PubMed

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

    2016-05-27

    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.

  12. 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.

  13. Review of Public Safety in Viewpoint of Complex Networks

    SciTech Connect

    Gai Chengcheng; Weng Wenguo; Yuan Hongyong

    2010-05-21

    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.

  14. 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

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

    PubMed

    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.

  16. 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.

  17. Protecting public health and global freight transportation systems during an influenza pandemic.

    PubMed

    Luke, Thomas C; Rodrigue, Jean-Paul

    2008-01-01

    The H5N1 influenza threat is resulting in global preparations for the next influenza pandemic. Pandemic influenza planners are prioritizing scarce vaccine, antivirals, and public health support for different segments of society. The freight, bulk goods, and energy transportation network comprise the maritime, rail, air, and trucking industries. It relies on small numbers of specialized workers who cannot be rapidly replaced if lost due to death, illness, or voluntary absenteeism. Because transportation networks link economies, provide critical infrastructures with working material, and supply citizens with necessary commodities, disrupted transportation systems can lead to cascading failures in social and economic systems. However, some pandemic influenza plans have assigned transportation workers a low priority for public health support, vaccine, and antivirals. The science of Transportation Geography demonstrates that transportation networks and workers are concentrated at, or funnel through, a small number of chokepoints and corridors. Chokepoints should be used to rapidly and efficiently vaccinate and prophylax the transportation worker cohort and to implement transmission prevention measures and thereby protect the ability to move goods. Nations, states, the transportation industry and unions, businesses, and other stakeholders must plan, resource, and exercise, and then conduct a transportation health assurance and security campaign for an influenza pandemic.

  18. Myosin-driven transport network in plants

    PubMed Central

    Kurth, Elizabeth G.; Peremyslov, Valera V.; Turner, Hannah L.; Makarova, Kira S.; Iranzo, Jaime; Mekhedov, Sergei L.; Koonin, Eugene V.; Dolja, Valerian V.

    2017-01-01

    We investigate the myosin XI-driven transport network in Arabidopsis using protein–protein interaction, subcellular localization, gene knockout, and bioinformatics analyses. The two major groups of nodes in this network are myosins XI and their membrane-anchored receptors (MyoB) that, together, drive endomembrane trafficking and cytoplasmic streaming in the plant cells. The network shows high node connectivity and is dominated by generalists, with a smaller fraction of more specialized myosins and receptors. We show that interaction with myosins and association with motile vesicles are common properties of the MyoB family receptors. We identify previously uncharacterized myosin-binding proteins, putative myosin adaptors that belong to two unrelated families, with four members each (MadA and MadB). Surprisingly, MadA1 localizes to the nucleus and is rapidly transported to the cytoplasm, suggesting the existence of myosin XI-driven nucleocytoplasmic trafficking. In contrast, MadA2 and MadA3, as well as MadB1, partition between the cytosolic pools of motile endomembrane vesicles that colocalize with myosin XI-K and diffuse material that does not. Gene knockout analysis shows that MadB1–4 contribute to polarized root hair growth, phenocopying myosins, whereas MadA1–4 are redundant for this process. Phylogenetic analysis reveals congruent evolutionary histories of the myosin XI, MyoB, MadA, and MadB families. All these gene families emerged in green algae and show concurrent expansions via serial duplication in flowering plants. Thus, the myosin XI transport network increased in complexity and robustness concomitantly with the land colonization by flowering plants and, by inference, could have been a major contributor to this process. PMID:28096376

  19. 28 CFR 36.310 - Transportation provided by public accommodations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... accommodations. 36.310 Section 36.310 Judicial Administration DEPARTMENT OF JUSTICE NONDISCRIMINATION ON THE 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...

  20. 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.

  1. 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

  2. Multiple Networks of Public School Administrators: An Analysis of Network Content and Structure

    ERIC Educational Resources Information Center

    Hite, Julie M.; Williams, Ellen J.; Baugh, Steven C.

    2005-01-01

    This study examines a public school administrator network from a qualitative paradigm using network theory and methods. Findings identify and describe four distinct networks emerging from administrators' relationships: the innovation network, the resource network, the social/emotional support network, and the university-school partnership network.…

  3. Evaluating transport in irregular pore networks

    NASA Astrophysics Data System (ADS)

    Klimenko, Dimitri A.; Hooman, Kamel; Klimenko, Alexander Y.

    2012-07-01

    A general approach for investigating transport phenomena in porous media is presented. This approach has the capacity to represent various kinds of irregularity in porous media without the need for excessive detail or computational effort. The overall method combines a generalized effective medium approximation (EMA) with a macroscopic continuum model in order to derive a transport equation with explicit analytical expressions for the transport coefficients. The proposed form of the EMA is an anisotropic and heterogeneous extension of Kirkpatrick's EMA [Rev. Mod. Phys.RMPHAT0034-686110.1103/RevModPhys.45.574 45, 574 (1973)] which allows the overall model to account for microscopic alterations in connectivity (with the locations of the pores and the orientation and length of the throat) as well as macroscopic variations in transport properties. A comparison to numerical results for randomly generated networks with different properties is given, indicating the potential for this methodology to handle cases that would pose significant difficulties to many other analytical models.

  4. Public Health Analysis Transport Optimization Model v. 1.0

    SciTech Connect

    Beyeler, Walt; Finley, Patrick; Walser, Alex; Frazier, Chris; Mitchell, Michael

    2016-10-05

    PHANTOM models logistic functions of national public health systems. The system enables public health officials to visualize and coordinate options for public health surveillance, diagnosis, response and administration in an integrated analytical environment. Users may simulate and analyze system performance applying scenarios that represent current conditions or future contingencies what-if analyses of potential systemic improvements. Public health networks are visualized as interactive maps, with graphical displays of relevant system performance metrics as calculated by the simulation modeling components.

  5. 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

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

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-05

    ... Practices for Crew and Space Flight Participants. We would like to explore industry views on medical best... Federal Aviation Administration Commercial Space Transportation Advisory Committee; Public Teleconference AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of Commercial Space...

  8. 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...

  9. Network analysis in public health: history, methods, and applications.

    PubMed

    Luke, Douglas A; Harris, Jenine K

    2007-01-01

    Network analysis is an approach to research that is uniquely suited to describing, exploring, and understanding structural and relational aspects of health. It is both a methodological tool and a theoretical paradigm that allows us to pose and answer important ecological questions in public health. In this review we trace the history of network analysis, provide a methodological overview of network techniques, and discuss where and how network analysis has been used in public health. We show how network analysis has its roots in mathematics, statistics, sociology, anthropology, psychology, biology, physics, and computer science. In public health, network analysis has been used to study primarily disease transmission, especially for HIV/AIDS and other sexually transmitted diseases; information transmission, particularly for diffusion of innovations; the role of social support and social capital; the influence of personal and social networks on health behavior; and the interorganizational structure of health systems. We conclude with future directions for network analysis in public health.

  10. 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...

  11. 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)

  12. Managing the Cooperative Network: The Public Administration Model.

    ERIC Educational Resources Information Center

    Diener, Ronald E.

    1981-01-01

    Recommends that library administrators turn to public administration models in preference to business administration models for network management; this choice is predicated on the not-for-profit aspects of public service organizations. (RAA)

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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...

  18. 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…

  19. User requirements and understanding of public health networks in England

    PubMed Central

    Fahey, D; Carson, E; Cramp, D; Muir, G

    2003-01-01

    Background: The movement of public health professionals from health authorities to primary care trusts has increased their isolation and dependence on public health networks for communication. Methods: A cross sectional survey of 60 public health professionals working in England was performed to determine their understanding of the term "public health network" and to explore the functions that they would like these networks to perform. It also assessed their attitudes towards a national network and towards individual, local, and national web sites to support these networks. Results: The most popular functions were the support of CPD/education, the identification of expertise and maximisation of scarce resources, information sharing, and efficient information/knowledge management. The local and national networks and their web sites should provide information on current projects of the network and searches to identify people, expertise, and reports. Conclusion: Public health professionals have a similar but broader understanding of the term "public health network" than that of the government with greater emphasis on sharing of information. The network is more likely to be successful if its priorities are maximising scarce resources, identification of expertise, CPD/education, and knowledge management. PMID:14652257

  20. 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…

  1. Complex quantum networks: From universal breakdown to optimal transport.

    PubMed

    Mülken, Oliver; Dolgushev, Maxim; Galiceanu, Mircea

    2016-02-01

    We study the transport efficiency of excitations on complex quantum networks with loops. For this we consider sequentially growing networks with different topologies of the sequential subgraphs. This can lead either to a universal complete breakdown of transport for complete-graph-like sequential subgraphs or to optimal transport for ringlike sequential subgraphs. The transition to optimal transport can be triggered by systematically reducing the number of loops of complete-graph-like sequential subgraphs in a small-world procedure. These effects are explained on the basis of the spectral properties of the network's Hamiltonian. Our theoretical considerations are supported by numerical Monte Carlo simulations for complex quantum networks with a scale-free size distribution of sequential subgraphs and a small-world-type transition to optimal transport.

  2. Complex quantum networks: From universal breakdown to optimal transport

    NASA Astrophysics Data System (ADS)

    Mülken, Oliver; Dolgushev, Maxim; Galiceanu, Mircea

    2016-02-01

    We study the transport efficiency of excitations on complex quantum networks with loops. For this we consider sequentially growing networks with different topologies of the sequential subgraphs. This can lead either to a universal complete breakdown of transport for complete-graph-like sequential subgraphs or to optimal transport for ringlike sequential subgraphs. The transition to optimal transport can be triggered by systematically reducing the number of loops of complete-graph-like sequential subgraphs in a small-world procedure. These effects are explained on the basis of the spectral properties of the network's Hamiltonian. Our theoretical considerations are supported by numerical Monte Carlo simulations for complex quantum networks with a scale-free size distribution of sequential subgraphs and a small-world-type transition to optimal transport.

  3. 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.

  4. 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.

  5. 77 FR 547 - Fiscal Year 2011 Public Transportation on Indian Reservations Program Project Selections

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-05

    ... of capital projects, operating costs, and planning activities for public transportation services on... Federal Transit Administration Fiscal Year 2011 Public Transportation on Indian Reservations Program... announcement of project selections. SUMMARY: The U.S. Department of Transportation's (DOT) Federal...

  6. 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.

  7. 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.

  8. 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.

  9. Service-aware transport network: opportunities and challenges

    NASA Astrophysics Data System (ADS)

    Pan, James; White, Ian M.; Black, Jim; Lima, Claudio; Rabinovich, Boris; Huang, Ray

    2005-02-01

    In this paper we propose a new concept of future service-aware transport networks that are built on converged wireless-wired transport networks, enable service layer convergence, and also support application layer convergence. This concept is derived from the emerging trend of business convergence among the telecommunication, cable, and entertainment segments, and technology convergence among the telecommunications, computer, and software industries. We also identify QoS as a technical backbone to future service-aware transport networks, and from the perspective of an integrated carrier having both wireless and wired assets, discuss related research opportunities and challenges, especially those involved in optical networks. We finally present an adaptive apparatus for high availability, capacity efficiency, and QoS-guaranteed protection and restoration for optical networks. This paper is intended to promote academic and industrial attention to some core technical challenges that lie ahead for the telecommunication industry and to spur strategically important research and perhaps also some standards activities.

  10. On the topology of optical transport networks

    NASA Astrophysics Data System (ADS)

    Cárdenas, J. P.; Santiago, A.; Losada, J. C.; Benito, R. M.; Mouronte, M. L.

    2010-09-01

    Synchronous Digital Hierarchy (SDH) is the standard technology for information transmission in broadband optical networks. Unlike systems with unplanned growth, such as those of natural origin or the Internet network, the SDH systems are strictly planned as rings, meshes, stars or tree-branches structures designed to connect different equipments. In spite of that, we have found that the SDH network operated by Telefónica in Spain shares remarkable topological properties with other real complex networks as a product of its evolution since 1992. In fact, we have found power-law scaling in the degree distribution (N·P(k) = k-γ) and small-world networks properties. The complexity found in SDH systems was reproduced by two models of complex networks, one of them considers real planning directives that take into account geographical and technological variables and the other one is based in the compatibility among SDH equipments.

  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.

  12. 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

  13. Implications of network structure on public health collaboratives.

    PubMed

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

    2013-10-01

    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 evolve, specifically in terms of how subsequent network structures are linked to outcomes. A systems science approach, that is, one that considers the interdependencies and nested features of networks, provides the appropriate methods to examine the complex nature of these networks. Applying Mays and Scutchfields's categorization of "structural signatures" (breadth, density, and centralization), this research examines how network structure influences the outcomes of public health collaboratives. Secondary data from the Program to Analyze, Record, and Track Networks to Enhance Relationships (www.partnertool.net) data set are analyzed. This data set consists of dyadic (N = 12,355), organizational (N = 2,486), and whole network (N = 99) data from public health collaborations around the United States. Network data are used to calculate structural signatures and weighted least squares regression is used to examine how network structures can predict selected intermediary outcomes (resource contributions, overall value and trust rankings, and outcomes) in public health collaboratives. Our findings suggest that network structure may have an influence on collaborative-related outcomes. The structural signature that had the most significant relationship to outcomes was density, with higher density indicating more positive outcomes. Also significant was the finding that more breadth creates new challenges such as difficulty in reaching consensus and creating ties with other members. However, assumptions that these structural components lead to improved outcomes for public health collaboratives may be slightly premature. Implications of

  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. 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.

  16. Models for a National Public School Computing Network.

    ERIC Educational Resources Information Center

    Bull, Glen L.; And Others

    1993-01-01

    Discusses a possible national education computer network that would include elementary, secondary, and higher education institutions. Topics addressed include Internet; common standards; distributed computing; open access; equity concerns; and examples of two successful public school networks in Virginia and Texas that are linked through the…

  17. 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.

  18. Rural health network development: public policy issues and state initiatives.

    PubMed

    Casey, M M; Wellever, A; Moscovice, I

    1997-02-01

    Rural health networks are a potential way for rural health care systems to improve access to care, reduce costs, and enhance quality of care. Networks provide a means for rural providers to contract with managed care organizations, develop their own managed care entities, share resources, and structure practice opportunities to support recruitment and retention of rural physicians and other health care professionals. The results of early network development initiatives indicate a need for state officials and others interested in encouraging network development to agree on common rural health network definitions, to identify clearly the goals of network development programs, and to document and analyze program outcomes. Future network development efforts need to be much more comprehensive if they are to have a significant impact on rural health care. This article analyzes public policy issues related to integrated rural health network development, discusses current efforts to encourage network development in rural areas, and suggests actions that states may take if they desire to support rural health network development. These actions include adopting a formal rural health network definition, providing networks with alternatives to certain regulatory requirements, and providing incentives such as matching grants, loans, or technical assistance. Without public sector support for networks, managed care options may continue to be unavailable in many less densely populated rural areas of the country, and locally controlled rural health networks are unlikely to develop as an alternative to the dominant pattern of managed care expansion by large urban entities. Implementation of Medicare reform legislation could provide significant incentives for the development of rural health networks, depending on the reimbursement provisions, financial solvency standards, and antitrust exemptions for provider-sponsored networks in the final legislation and federal regulations.

  19. 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

    ... safety in urban mass transportation. See, e.g., Amalgamated Transit Union v. Skinner, 894 F.2d 1362, 1364... Program B. The Safety Management System Approach C. Transit Asset Management II. The Relationship Between.... Background A. The Need for a Comprehensive National Safety Program B. The Need for a National Transit...

  20. 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.

  1. 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…

  2. 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. 90.19 Section 90.19 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Public Safety Radio Pool § 90.19 Nationwide...

  3. 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. 90.19 Section 90.19 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Public Safety Radio Pool § 90.19 Nationwide...

  4. 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.

  5. PONS - Mobility Assistance on Footpaths for Public Transportation.

    PubMed

    Koutny, Reinhard; Miesenberger, Klaus

    2015-01-01

    This paper presents an ongoing project targeting mobility support for users of public transportation including people with limited mobility. Existing approaches in this field mostly offer non-continuous guidance during the whole journey including multiple rides with different vehicles and footpaths in between at transfer points. Especially people with limited mobility, like people with disabilities and elderly people, or travelers who are not familiar with the specific route or transfer point, like tourists, often struggle with public transportation. They crave for a seamless approach covering all links of the mobility chain - the sequence of sections of the whole route - and providing comprehensive assistance throughout the whole journey. Previous projects and widespread experiences of project partners revealed that especially footpath sections are lacking proper support. In particular, the consortium identified three problem areas in existing approaches when dealing with footpath sections: (1) A lack of information, (2) a lack of orientation and (3) a lack of provision of services. In order to bridge (lat. PONS) these gaps in the mobility chain, new paradigms and technology concepts are developed to tackle the shortcomings on footpaths and combined in a toolkit to help developers of applications with focus on pedestrian navigation and public transport to improve their solutions with sustainable and state-of-the-art approaches.

  6. Analysis of the Chinese provincial air transportation network

    NASA Astrophysics Data System (ADS)

    Du, Wen-Bo; Liang, Bo-Yuan; Hong, Chen; Lordan, Oriol

    2017-01-01

    The air transportation system is of a great impact on the economy and globalization of a country. In this paper, we analyze the Chinese air transportation network (ATN) from a provincial perspective via the complex network framework, where all airports located in one province are abstracted as a single node and flights between two provinces are denoted by a link. The results show that the network exhibits small-world property, homogeneous structure and disassortative mixing. The variation of the flight flow within 24 h is investigated and an obvious tide phenomenon is found in the dynamics of Chinese provincial ATN for high output level of tertiary industry. Our work will offer a novel approach for understanding the characteristic of the Chinese air transportation network.

  7. 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

  8. Digital Networked Information Society and Public Health: Problems and Promises of Networked Health Communication of Lay Publics.

    PubMed

    Kim, Jeong-Nam

    2016-11-29

    This special issue of Health Communication compiles 10 articles to laud the promise and yet confront the problems in the digital networked information society related to public health. We present this anthology of symphony and cacophony of lay individuals' communicative actions in a digital networked information society. The collection of problems and promise of the new digital world may be a cornerstone joining two worlds-pre- and postdigital network society-and we hope this special issue will help better shape our future states of public health.

  9. Sailor: Maryland's Online Public Information Network. Sailor Network Assessment Final Report: Findings and Future Sailor Network Development.

    ERIC Educational Resources Information Center

    Bertot, John Carlo; McClure, Charles R.

    This report describes the results of an assessment of Sailor, Maryland's Online Public Information Network, which provides statewide Internet connection to 100% of Maryland public libraries. The concept of a "statewide networked environment" includes information services, products, hardware and software, telecommunications…

  10. Transportation dynamics on coupled networks with limited bandwidth

    NASA Astrophysics Data System (ADS)

    Li, Ming; Hu, Mao-Bin; Wang, Bing-Hong

    2016-12-01

    The communication networks in real world often couple with each other to save costs, which results in any network does not have a stand-alone function and efficiency. To investigate this, in this paper we propose a transportation model on two coupled networks with bandwidth sharing. We find that the free-flow state and the congestion state can coexist in the two coupled networks, and the free-flow path and congestion path can coexist in each network. Considering three bandwidth-sharing mechanisms, random, assortative and disassortative couplings, we also find that the transportation capacity of the network only depends on the coupling mechanism, and the fraction of coupled links only affects the performance of the system in the congestion state, such as the traveling time. In addition, with assortative coupling, the transportation capacity of the system will decrease significantly. However, the disassortative coupling has little influence on the transportation capacity of the system, which provides a good strategy to save bandwidth. Furthermore, a theoretical method is developed to obtain the bandwidth usage of each link, based on which we can obtain the congestion transition point exactly.

  11. Transportation dynamics on coupled networks with limited bandwidth.

    PubMed

    Li, Ming; Hu, Mao-Bin; Wang, Bing-Hong

    2016-12-14

    The communication networks in real world often couple with each other to save costs, which results in any network does not have a stand-alone function and efficiency. To investigate this, in this paper we propose a transportation model on two coupled networks with bandwidth sharing. We find that the free-flow state and the congestion state can coexist in the two coupled networks, and the free-flow path and congestion path can coexist in each network. Considering three bandwidth-sharing mechanisms, random, assortative and disassortative couplings, we also find that the transportation capacity of the network only depends on the coupling mechanism, and the fraction of coupled links only affects the performance of the system in the congestion state, such as the traveling time. In addition, with assortative coupling, the transportation capacity of the system will decrease significantly. However, the disassortative coupling has little influence on the transportation capacity of the system, which provides a good strategy to save bandwidth. Furthermore, a theoretical method is developed to obtain the bandwidth usage of each link, based on which we can obtain the congestion transition point exactly.

  12. 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.

  13. Transportation dynamics on coupled networks with limited bandwidth

    PubMed Central

    Li, Ming; Hu, Mao-Bin; Wang, Bing-Hong

    2016-01-01

    The communication networks in real world often couple with each other to save costs, which results in any network does not have a stand-alone function and efficiency. To investigate this, in this paper we propose a transportation model on two coupled networks with bandwidth sharing. We find that the free-flow state and the congestion state can coexist in the two coupled networks, and the free-flow path and congestion path can coexist in each network. Considering three bandwidth-sharing mechanisms, random, assortative and disassortative couplings, we also find that the transportation capacity of the network only depends on the coupling mechanism, and the fraction of coupled links only affects the performance of the system in the congestion state, such as the traveling time. In addition, with assortative coupling, the transportation capacity of the system will decrease significantly. However, the disassortative coupling has little influence on the transportation capacity of the system, which provides a good strategy to save bandwidth. Furthermore, a theoretical method is developed to obtain the bandwidth usage of each link, based on which we can obtain the congestion transition point exactly. PMID:27966624

  14. 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...

  15. 49 CFR 37.41 - Construction 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 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...

  16. 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 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...

  17. 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 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...

  18. 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...

  19. 49 CFR 37.41 - Construction 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 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...

  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 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...

  1. 49 CFR 37.41 - Construction 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 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...

  2. 49 CFR 37.41 - Construction 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 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...

  3. 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 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...

  4. Bus transport network model with ideal n-depth clique network topology

    NASA Astrophysics Data System (ADS)

    Yang, Xu-Hua; Chen, Guang; Sun, Bao; Chen, Sheng-Yong; Wang, Wan-Liang

    2011-11-01

    We propose an ideal n-depth clique network model. In this model, the original network is composed of cliques (maximal complete subgraphs) that overlap with each other. The network expands continuously by the addition of new cliques. The final diameter of the network can be set in advance, namely, it is controllable. Assuming that the diameter of the network is n, the network exhibits a logistic structure with (n+1) layers. In this structure, the 0th layer represents the original network and each node of the (m)th layer (1≤m≤n) corresponds to a clique in the (m-1)th layer. In the growth process of the network, we ensure that any (m)th layer network is composed of overlapping cliques. Any node in an (m)th layer network corresponds to an m-depth community in the original network, and the diameter of an m-depth community is m. Therefore, the (n-1)th layer network will contain only one clique, the (n)th layer network will contain only one node, and the diameter of the corresponding original network is n. Then an ideal n-depth clique network will be obtained. Based on the ideal n-depth clique network model, we construct a bus transport network model with an ideal n-depth clique network topology (ICNBTN). Moreover, our study compares this model with the real bus transport network (RealBTN) of three major cities in China and a recently introduced bus transport network model (BTN) whose network properties correspond well with those of real BTNs. The network properties of the ICNBTN are much closer to those of the RealBTN than those of the BTN are. At the same time, the ICNBTN has higher clustering extent of bus routes, smaller network diameter, which corresponds to shorter maximum transfer times in a bus network, and lower average shortest path time coefficient than the BTN and the RealBTN. Therefore, the ICNBTN can achieve higher transfer efficiency for a bus transport system.

  5. Current-reinforced random walks for constructing transport networks

    PubMed Central

    Ma, Qi; Johansson, Anders; Tero, Atsushi; Nakagaki, Toshiyuki; Sumpter, David J. T.

    2013-01-01

    Biological systems that build transport networks, such as trail-laying ants and the slime mould Physarum, can be described in terms of reinforced random walks. In a reinforced random walk, the route taken by ‘walking’ particles depends on the previous routes of other particles. Here, we present a novel form of random walk in which the flow of particles provides this reinforcement. Starting from an analogy between electrical networks and random walks, we show how to include current reinforcement. We demonstrate that current-reinforcement results in particles converging on the optimal solution of shortest path transport problems, and avoids the self-reinforcing loops seen in standard density-based reinforcement models. We further develop a variant of the model that is biologically realistic, in the sense that the particles can be identified as ants and their measured density corresponds to those observed in maze-solving experiments on Argentine ants. For network formation, we identify the importance of nonlinear current reinforcement in producing networks that optimize both network maintenance and travel times. Other than ant trail formation, these random walks are also closely related to other biological systems, such as blood vessels and neuronal networks, which involve the transport of materials or information. We argue that current reinforcement is likely to be a common mechanism in a range of systems where network construction is observed. PMID:23269849

  6. Improving travel projections for public transportation. Research report

    SciTech Connect

    Perkinson, D.G.; Keitgen, B.

    1995-08-01

    Public transportation use saves energy and reduces emissions by taking people out of single passenger automobiles and putting them into high occupancy, energy efficient transit vehicles. Furthermore, public transit ridership and vehicular trip estimates are the base information required for estimating energy consumption and air pollution. Trip generation models as developed and used within Texas predict the number of trips expected to occur in a typical 24-hour day. The need to estimate peak-period trips has generated innovative techniques for estimating peak period travel from the 24 hour trip tables. Improved methods of estimating the number of trips that will generated during the peak period will potentially improve the estimation of ridership on public transportation, as well as related energy and emission forecasts. This project produced a trip generation model for predicting peak-period trips based on the travel surveys conducted in Texas during 1990 and 1991 for Amarillo, Beaumont-Port Arthur, Brownsville, San Antonio, Sherman-Denison, and Tyler.

  7. 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

  8. 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...

  9. 77 FR 71430 - New Agency Information Collection Activity Under OMB Review: Public Transportation Baseline...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-30

    ... SECURITY Transportation Security Administration New Agency Information Collection Activity Under OMB Review: Public Transportation Baseline Assessment for Security Enhancement (BASE) Program AGENCY: Transportation Security Administration, DHS. ACTION: 30-day notice. SUMMARY: This notice announces that the...

  10. 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...

  11. 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.

  12. An artificial neural network based groundwater flow and transport simulator

    SciTech Connect

    Krom, T.D.; Rosbjerg, D.

    1998-07-01

    Artificial neural networks are investigated as a tool for the simulation of contaminant loss and recovery in three-dimensional heterogeneous groundwater flow and contaminant transport modeling. These methods have useful applications in expert system development, knowledge base development and optimization of groundwater pollution remediation. The numerical model runs used to develop the artificial neural networks can be re-used to develop artificial neural networks to address alternative optimization problems or changed formulations of the constraints and or objective function under optimization. Artificial neural networks have been analyzed with the goal of estimating objectives which normally require the use of traditional flow and transport codes: such as contaminant recovery, contaminant loss (unrecovered) and remediation failure. The inputs to the artificial neutral networks are variable pumping withdrawal rates at fairly unconstrained 3-D locations. A forward-feed backwards error propagation artificial neural network architecture is used. The significance of the size of the training set, network architecture, and network weight optimization algorithm with respect to the estimation accuracy and objective are shown to be important. Finally, the quality of the weight optimization is studied via cross-validation techniques. This is demonstrated to be a useful method for judging training performance for strongly under-described systems.

  13. 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.

  14. 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.

  15. Photo-induced Mass Transport through Polymer Networks

    NASA Astrophysics Data System (ADS)

    Meng, Yuan; Anthamatten, Mitchell

    2014-03-01

    Among adaptable materials, photo-responsive polymers are especially attractive as they allow for spatiotemporal stimuli and response. We have recently developed a macromolecular network capable of photo-induced mass transport of covalently bound species. The system comprises of crosslinked chains that form an elastic network and photosensitive fluorescent arms that become mobile upon irradiation. We form loosely crosslinked polymer networks by Michael-Addition between multifunctional thiols and small molecule containing acrylate end-groups. The arms are connected to the network by allyl sulfide, that undergoes addition-fragmentation chain transfer (AFCT) in the presence of free radicals, releasing diffusible fluorophore. The networks are loaded with photoinitiator to allow for spatial modulation of the AFCT reactions. FRAP experiments within bulk elastomers are conducted to establish correlations between the fluorophore's diffusion coefficient and experimental variables such as network architecture, temperature and UV intensity. Photo-induced mass transport between two contacted films is demonstrated, and release of fluorophore into a solvent is investigated. Spatial and temporal control of mass transport could benefit drug release, printing, and sensing applications.

  16. Predicting Heat Transport across Multiple Devices with Neural Networks

    NASA Astrophysics Data System (ADS)

    Luna, C. J.; Budny, R. V.; Meneghini, O.; Smith, S. P.; Penna, J.

    2014-10-01

    Three multi-layer, feed-forward, back-propagation neural networks have been built and trained on heat transport data from DIII-D, TFTR, and JET, respectively. A comparative analysis shows that previous success of neural networks in predicting heat transport in DIII-D is reproduced for both TFTR and JET. The effect of using different neural network topologies has been investigated across all of the devices. It is found that the neural networks can consistently predict the total species' heat fluxes for all of the devices, however they have difficulty in predicting the individual components of the heat fluxes in presence of significant transient variations in stored energy (i.e. non steady-state conditions). Such limitation has been addressed by providing the time-derivative information of the plasma parameters that are input to the neural network. Finally, an attempt is made to draw a connection between the most consistently successful neural network topologies and their relevance to the physics of heat transport in tokamak plasmas. Supported in part by U.S. DoE Contracts No. DE-AC02-09CH1146 and No. DE-FG02-95ER54309.

  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. 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.

  19. Lower back pain and absenteeism among professional public transport drivers.

    PubMed

    Kresal, Friderika; Roblek, Vasja; Jerman, Andrej; Meško, Maja

    2015-01-01

    Drivers in public transport are subjected to lower back pain. The reason for the pain is associated with the characteristics of the physical position imposed on the worker while performing the job. Lower back pain is the main cause of absenteeism among drivers. The present study includes 145 public transport drivers employed as professional drivers for an average of 14.14 years. Analysis of the data obtained in the study includes the basic descriptive statistics, χ(2) test and multiple regression analysis. Analysis of the incidence of lower back pain showed that the majority of our sample population suffered from pain in the lower back. We found that there are no statistically significant differences between the groups formed by the length of service as a professional driver and incidence of lower back pain; we were also interested in whether or not the risk factors of lower back pain affects the absenteeism of city bus drivers. Analysis of the data has shown that the risk factors of pain in the lower part of the spine do affect the absenteeism of city bus drivers.

  20. Oil Price Uncertainty, Transport Fuel Demand and Public Health

    PubMed Central

    He, Ling-Yun; Yang, Sheng; Chang, Dongfeng

    2017-01-01

    Based on the panel data of 306 cities in China from 2002 to 2012, this paper investigates China’s road transport fuel (i.e., gasoline and diesel) demand system by using the Almost Ideal Demand System (AIDS) and the Quadratic AIDS (QUAIDS) models. The results indicate that own-price elasticities for different vehicle categories range from −1.215 to −0.459 (by AIDS) and from −1.399 to −0.369 (by QUAIDS). Then, this study estimates the air pollution emissions (CO, NOx and PM2.5) and public health damages from the road transport sector under different oil price shocks. Compared to the base year 2012, results show that a fuel price rise of 30% can avoid 1,147,270 tonnes of pollution emissions; besides, premature deaths and economic losses decrease by 16,149 cases and 13,817.953 million RMB yuan respectively; while based on the non-linear health effect model, the premature deaths and total economic losses decrease by 15,534 and 13,291.4 million RMB yuan respectively. Our study combines the fuel demand and health evaluation models and is the first attempt to address how oil price changes influence public health through the fuel demand system in China. Given its serious air pollution emission and substantial health damages, this paper provides important insights for policy makers in terms of persistent increasing in fuel consumption and the associated health and economic losses. PMID:28257076

  1. Oil Price Uncertainty, Transport Fuel Demand and Public Health.

    PubMed

    He, Ling-Yun; Yang, Sheng; Chang, Dongfeng

    2017-03-01

    Based on the panel data of 306 cities in China from 2002 to 2012, this paper investigates China's road transport fuel (i.e., gasoline and diesel) demand system by using the Almost Ideal Demand System (AIDS) and the Quadratic AIDS (QUAIDS) models. The results indicate that own-priceelasticitiesfordifferentvehiclecategoriesrangefrom-1.215to-0.459(byAIDS)andfrom -1.399 to-0.369 (by QUAIDS). Then, this study estimates the air pollution emissions (CO, NOx and PM2.5) and public health damages from the road transport sector under different oil price shocks. Compared to the base year 2012, results show that a fuel price rise of 30% can avoid 1,147,270 tonnes of pollution emissions; besides, premature deaths and economic losses decrease by 16,149 cases and 13,817.953 million RMB yuan respectively; while based on the non-linear health effect model, the premature deaths and total economic losses decrease by 15,534 and 13,291.4 million RMB yuan respectively. Our study combines the fuel demand and health evaluation models and is the first attempt to address how oil price changes influence public health through the fuel demand system in China. Given its serious air pollution emission and substantial health damages, this paper provides important insights for policy makers in terms of persistent increasing in fuel consumption and the associated health and economic losses.

  2. 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

  3. Public psychiatry fellowships: a developing network of public-academic collaborations.

    PubMed

    Le Melle, Stephanie; Mangurian, Christina; Ali, Osman M; Giggie, Marisa A; Hadley, Trevor; Lewis, Marshall E; Runnels, Patrick; Sowers, Wesley; Steiner, Jeanne L; Trujillo, Manuel; Ranz, Jules M

    2012-09-01

    In response to the expanding public behavioral health care system, a network of 15 public-community psychiatry fellowships has developed over the past six years. The fellowship directors meet yearly to sustain and develop fellowships to recruit and retain psychiatrists in the public sector. This column describes five types of public-academic collaborations on which the fellowships are based. The collaborations focus on structural and fiscal arrangements; recruitment and retention; program evaluation, program research, and policy; primary care integration; and career development. These collaborations serve to train psychiatrists who will play a key role in the rapidly evolving health care system.

  4. Simulating unsteady flow and sediment transport in vegetated channel network

    NASA Astrophysics Data System (ADS)

    Bai, Yang; Duan, Jennifer G.

    2014-07-01

    This paper presents a one-dimensional model for simulating flood routing and sediment transport over mobile alluvium in a vegetated channel network. The modified St. Venant equations together with the governing equations for suspended sediment and bed load transport were solved simultaneously to obtain flow properties and sediment transport rate. The Godunov-type finite volume method is employed to discretize the governing equations. Then, the Exner equation was solved for bed elevation change. Since sediment transport is non-equilibrium when bed is degrading or aggrading, a recovery coefficient for suspended sediment and an adaptation length for bed load transport were used to quantify the differences between equilibrium and non-equilibrium sediment transport rate. The influence of vegetation on floodplain and main channel was accounted for by adjusting resistance terms in the momentum equations for flow field. A procedure to separate the grain resistance from the total resistance was proposed and implemented to calculate sediment transport rate. The model was tested by a flume experiment case and an unprecedented flood event occurred in the Santa Cruz River, Tucson, Arizona, in July 2006. Simulated results of flow discharge and bed elevation changes showed satisfactory agreements with the measurements. The impacts of vegetation density on sediment transport and significance of non-equilibrium sediment transport model were discussed.

  5. Diffusive transport in networks built of containers and tubes.

    PubMed

    Lizana, L; Konkoli, Z

    2005-08-01

    We have developed analytical and numerical methods to study the transport of noninteracting particles in large networks consisting of M d -dimensional containers C1,...,C(M) with radii R(i) linked together by tubes of length l(ij) and radii a(ij) where i,j = 1,2,...,M. Tubes may join directly with each other, forming junctions. It is possible that some links are absent. Instead of solving the diffusion equation for the full problem we formulated an approach that is computationally more efficient. We derived a set of rate equations that govern the time dependence of the number of particles in each container, N1(t), N2(t),...,N(M)(t). In such a way the complicated transport problem is reduced to a set of M first-order integro-differential equations in time, which can be solved efficiently by the algorithm presented here. The workings of the method have been demonstrated on a couple of examples: networks involving three, four, and seven containers and one network with a three-point junction. Already simple networks with relatively few containers exhibit interesting transport behavior. For example, we showed that it is possible to adjust the geometry of the networks so that the particle concentration varies in time in a wave-like manner. Such behavior deviates from simple exponential growth and decay occurring in the two-container system.

  6. Transport efficiency and dynamics of hydraulic fracture networks

    NASA Astrophysics Data System (ADS)

    Sachau, Till; Bons, Paul; Gomez-Rivas, Enrique

    2015-08-01

    Intermittent fluid pulses in the Earth's crust can explain a variety of geological phenomena, for instance the occurrence of hydraulic breccia. Fluid transport in the crust is usually modeled as continuous darcian flow, ignoring that sufficient fluid overpressure can cause hydraulic fractures as fluid pathways with very dynamic behavior. Resulting hydraulic fracture networks are largely self-organized: opening and healing of hydraulic fractures depends on local fluid pressure, which is, in turn, largely controlled by the fracture network. We develop a crustal-scale 2D computer model designed to simulate this process. To focus on the dynamics of the process we chose a setup as simple as possible. Control factors are constant overpressure at a basal fluid source and a constant 'viscous' parameter controlling fracture-healing. Our results indicate that at large healing rates hydraulic fractures are mobile, transporting fluid in intermittent pulses to the surface and displaying a 1/fα behavior. Low healing rates result in stable networks and constant flow. The efficiency of the fluid transport is independent from the closure dynamics of veins or fractures. More important than preexisting fracture networks is the distribution of fluid pressure. A key requirement for dynamic fracture networks is the presence of a fluid pressure gradient.

  7. 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

  8. Properties of transportation dynamics on scale-free networks

    NASA Astrophysics Data System (ADS)

    Zheng, Jian-Feng; Gao, Zi-You; Zhao, Xiao-Mei

    2007-01-01

    In this work, we study the statistical properties of transportation dynamics considering congestion effects, based on the standard Barabási-Albert scale-free model. In terms of user equilibrium (UE) condition, congestion effects can be described by cost function. Simulation results demonstrate that the cumulative load distribution exhibits a power-law behavior with Pl∼l, where l is the flow loaded on the node and γ≈2.7 which is much bigger than that obtained in many networks without considering congestion effects. That is, there exist fewer heavily loaded nodes in the network when considering congestion effects. Furthermore, by numerically investigating overload phenomenon of the heaviest loaded link removal in transportation networks, a phase-transition phenomenon is uncovered in terms of the key parameter characterizing the node capacity.

  9. Transporting live video over high packet loss networks

    NASA Astrophysics Data System (ADS)

    Werdin, Dave

    2013-05-01

    Transport of live video requires a robust backbone as live video decoders are subject to dropouts and buffer starvation. A short duration packet loss will many times cause a decoder to go black for many seconds as it reacquires the stream and clock. IP networks due to their connectionless approach and support for variable length packets, inherently display packet delivery variability. These characteristics most typically include packet loss, packet delay variation, and packets being delivered out of order. Deep Packet Recovery (DPR) techniques provide correction to IP network induced errors and issues. DPR can provide a much broader and stronger protection than traditional Forward Error Correction techniques enabling transport of live video across severely impaired networks.

  10. Mixed transportation network design under a sustainable development perspective.

    PubMed

    Qin, Jin; Ni, Ling-lin; Shi, Feng

    2013-01-01

    A mixed transportation network design problem considering sustainable development was studied in this paper. Based on the discretization of continuous link-grade decision variables, a bilevel programming model was proposed to describe the problem, in which sustainability factors, including vehicle exhaust emissions, land-use scale, link load, and financial budget, are considered. The objective of the model is to minimize the total amount of resources exploited under the premise of meeting all the construction goals. A heuristic algorithm, which combined the simulated annealing and path-based gradient projection algorithm, was developed to solve the model. The numerical example shows that the transportation network optimized with the method above not only significantly alleviates the congestion on the link, but also reduces vehicle exhaust emissions within the network by up to 41.56%.

  11. 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.

  12. 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

  13. 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.

  14. From patchwork to national network: working collaboratively to create a national environmental public health tracking network.

    PubMed

    Li, Jennifer; Dawson, Becky

    2008-01-01

    Partnership and collaboration are hallmarks for the National Environmental Public Health Tracking Network (EPHT) Program. When CDC issued its first request for proposals for EPHT in August 2002, it required formal collaboration between state public health and environmental protection agencies. In addition, each of the grantees assembled a planning consortium or technical advisory committee to aid in the creation of the National EPHT together with local health agencies, community groups, industry, and healthcare professionals and other organizations. Partnerships have resulted in actions that protect and monitor public health; substantial the development and use of state and national tracking networks; and increase collaboration and information sharing.

  15. 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.

  16. Performance verification of network function virtualization in software defined optical transport networks

    NASA Astrophysics Data System (ADS)

    Zhao, Yongli; Hu, Liyazhou; Wang, Wei; Li, Yajie; Zhang, Jie

    2017-01-01

    With the continuous opening of resource acquisition and application, there are a large variety of network hardware appliances deployed as the communication infrastructure. To lunch a new network application always implies to replace the obsolete devices and needs the related space and power to accommodate it, which will increase the energy and capital investment. Network function virtualization1 (NFV) aims to address these problems by consolidating many network equipment onto industry standard elements such as servers, switches and storage. Many types of IT resources have been deployed to run Virtual Network Functions (vNFs), such as virtual switches and routers. Then how to deploy NFV in optical transport networks is a of great importance problem. This paper focuses on this problem, and gives an implementation architecture of NFV-enabled optical transport networks based on Software Defined Optical Networking (SDON) with the procedure of vNFs call and return. Especially, an implementation solution of NFV-enabled optical transport node is designed, and a parallel processing method for NFV-enabled OTN nodes is proposed. To verify the performance of NFV-enabled SDON, the protocol interaction procedures of control function virtualization and node function virtualization are demonstrated on SDON testbed. Finally, the benefits and challenges of the parallel processing method for NFV-enabled OTN nodes are simulated and analyzed.

  17. 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

  18. 76 FR 49832 - Notice of Market Assessment and Public Meeting for Digital Transportation Exchange

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-11

    ... Office of the Secretary Notice of Market Assessment and Public Meeting for Digital Transportation... investors like never before--creating a thriving marketplace for digital transportation solutions. The Digital Transportation Exchange (DTE) will be a public exchange where citizens, businesses, state...

  19. 77 FR 69899 - Public Conference on Geographic Information Systems (GIS) in Transportation Safety

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-21

    ... SAFETY BOARD Public Conference on Geographic Information Systems (GIS) in Transportation Safety The National Transportation Safety Board will hold a public conference on the use of the Geographic Information Systems (GIS) in transportation safety on December 4-5, 2012. GIS is a rapidly expanding group...

  20. 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.

  1. Mitigation of chemical attacks in enclosed public transportation facilities

    NASA Astrophysics Data System (ADS)

    Swansiger, William A.; Brockmann, John E.

    1998-12-01

    Public transportation facilities in the United States are vulnerable to attack by terrorists using chemical agents. This paper focuses on the problem of protecting the people in underground subway stations, which are among the most difficult facilities to protect. A nerve agent can produce symptoms in seconds to minutes, so immediate triggering of evacuation alarms and initiation of mitigation measures is necessary to minimize casualties in the station. The question of whether currently available chemical detectors are sufficiently capable and reliable to enable an automated response is addressed and augmentation possibilities are discussed. A number of concepts for mitigating chemical attacks are explored and their applicability to other transportation facilities is discussed. A possible near-term mitigation measure that is reviewed in some detail is the use of water sprays to scrub gasses and aerosols from the air. This technique may have applicability in the station at the point of agent release, as well as for detoxification of the air stream if selective venting is employed. Calculations show that with proper spray nozzle selection, the water pressure and flow rate available at some subway stations for fire suppression is sufficient for effective removal of Sarin from an air stream.

  2. Selecting public relations personnel of hospitals by analytic network process.

    PubMed

    Liao, Sen-Kuei; Chang, Kuei-Lun

    2009-01-01

    This study describes the use of analytic network process (ANP) in the Taiwanese hospital public relations personnel selection process. Starting with interviewing 48 practitioners and executives in north Taiwan, we collected selection criteria. Then, we retained the 12 critical criteria that were mentioned above 40 times by theses respondents, including: interpersonal skill, experience, negotiation, language, ability to follow orders, cognitive ability, adaptation to environment, adaptation to company, emotion, loyalty, attitude, and Response. Finally, we discussed with the 20 executives to take these important criteria into three perspectives to structure the hierarchy for hospital public relations personnel selection. After discussing with practitioners and executives, we find that selecting criteria are interrelated. The ANP, which incorporates interdependence relationships, is a new approach for multi-criteria decision-making. Thus, we apply ANP to select the most optimal public relations personnel of hospitals. An empirical study of public relations personnel selection problems in Taiwan hospitals is conducted to illustrate how the selection procedure works.

  3. 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.

  4. 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.

  5. Optimal resource allocation in random networks with transportation bandwidths

    NASA Astrophysics Data System (ADS)

    Yeung, C. H.; Wong, K. Y. Michael

    2009-03-01

    We apply statistical physics to study the task of resource allocation in random sparse networks with limited bandwidths for the transportation of resources along the links. Recursive relations from the Bethe approximation are converted into useful algorithms. Bottlenecks emerge when the bandwidths are small, causing an increase in the fraction of idle links. For a given total bandwidth per node, the efficiency of allocation increases with the network connectivity. In the high connectivity limit, we find a phase transition at a critical bandwidth, above which clusters of balanced nodes appear, characterized by a profile of homogenized resource allocation similar to the Maxwell construction.

  6. 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.

  7. Using Social Network Analysis to Assess Mentorship and Collaboration in a Public Health Network

    PubMed Central

    Belza, Basia; Leith, Katherine; Allen, Peg; Coe, Norma B.; Anderson, Lynda A.

    2015-01-01

    Introduction Addressing chronic disease burden requires the creation of collaborative networks to promote systemic changes and engage stakeholders. Although many such networks exist, they are rarely assessed with tools that account for their complexity. This study examined the structure of mentorship and collaboration relationships among members of the Healthy Aging Research Network (HAN) using social network analysis (SNA). Methods We invited 97 HAN members and partners to complete an online social network survey that included closed-ended questions about HAN-specific mentorship and collaboration during the previous 12 months. Collaboration was measured by examining the activity of the network on 6 types of products: published articles, in-progress manuscripts, grant applications, tools, research projects, and presentations. We computed network-level measures such as density, number of components, and centralization to assess the cohesiveness of the network. Results Sixty-three respondents completed the survey (response rate, 65%). Responses, which included information about collaboration with nonrespondents, suggested that 74% of HAN members were connected through mentorship ties and that all 97 members were connected through at least one form of collaboration. Mentorship and collaboration ties were present both within and across boundaries of HAN member organizations. Conclusion SNA of public health collaborative networks provides understanding about the structure of relationships that are formed as a result of participation in network activities. This approach may offer members and funders a way to assess the impact of such networks that goes beyond simply measuring products and participation at the individual level. PMID:26292061

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

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-05

    ...] [FR Doc No: 2013-13304] DEPARTMENT OF TRANSPORTATION Federal Transit Administration Limitation on Claims Against Proposed Public Transportation Projects AGENCY: Federal Transit Administration (FTA), DOT. ACTION: Notice. SUMMARY: This notice announces final environmental actions taken by the Federal...

  10. 78 FR 1301 - Fiscal Year 2012 Public Transportation on Indian Reservations Program Project Selections

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-08

    ... Federal Transit Administration Fiscal Year 2012 Public Transportation on Indian Reservations Program Project Selections AGENCY: Federal Transit Administration (FTA), DOT. ACTION: Tribal transit program announcement of project selections. SUMMARY: The US. Department of Transportation's (DOT) Federal...

  11. Global analysis for spread of infectious diseases via transportation networks.

    PubMed

    Nakata, Yukihiko; Röst, Gergely

    2015-05-01

    We formulate an epidemic model for the spread of an infectious disease along with population dispersal over an arbitrary number of distinct regions. Structuring the population by the time elapsed since the start of travel, we describe the infectious disease dynamics during transportation as well as in the regions. As a result, we obtain a system of delay differential equations. We define the basic reproduction number R(0) as the spectral radius of a next generation matrix. For multi-regional systems with strongly connected transportation networks, we prove that if R(0) ≤ 1 then the disease will be eradicated from each region, while if R(0) > 1 there is a globally asymptotically stable equilibrium, which is endemic in every region. If the transportation network is not strongly connected, then the model analysis shows that numerous endemic patterns can exist by admitting a globally asymptotically stable equilibrium, which may be disease free in some regions while endemic in other regions. We provide a procedure to detect the disease free and the endemic regions according to the network topology and local reproduction numbers. The main ingredients of the mathematical proofs are the inductive applications of the theory of asymptotically autonomous semiflows and cooperative dynamical systems. We visualise stability boundaries of equilibria in a parameter plane to illustrate the influence of the transportation network on the disease dynamics. For a system consisting of two regions, we find that due to spatial heterogeneity characterised by different local reproduction numbers, R(0) may depend non-monotonically on the dispersal rates, thus travel restrictions are not always beneficial.

  12. 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).

  13. Pore network model of electrokinetic transport through charged porous media

    NASA Astrophysics Data System (ADS)

    Obliger, Amaël; Jardat, Marie; Coelho, Daniel; Bekri, Samir; Rotenberg, Benjamin

    2014-04-01

    We introduce a method for the numerical determination of the steady-state response of complex charged porous media to pressure, salt concentration, and electric potential gradients. The macroscopic fluxes of solvent, salt, and charge are computed within the framework of the Pore Network Model (PNM), which describes the pore structure of the samples as networks of pores connected to each other by channels. The PNM approach is used to capture the couplings between solvent and ionic flows which arise from the charge of the solid surfaces. For the microscopic transport coefficients on the channel scale, we take a simple analytical form obtained previously by solving the Poisson-Nernst-Planck and Stokes equations in a cylindrical channel. These transport coefficients are upscaled for a given network by imposing conservation laws for each pores, in the presence of macroscopic gradients across the sample. The complex pore structure of the material is captured by the distribution of channel diameters. We investigate the combined effects of this complex geometry, the surface charge, and the salt concentration on the macroscopic transport coefficients. The upscaled numerical model preserves the Onsager relations between the latter, as expected. The calculated macroscopic coefficients behave qualitatively as their microscopic counterparts, except for the permeability and the electro-osmotic coupling coefficient when the electrokinetic effects are strong. Quantitatively, the electrokinetic couplings increase the difference between the macroscopic coefficients and the corresponding ones for a single channel of average diameter.

  14. Bus transport network of Shenyang considering competitive and cooperative relationship

    NASA Astrophysics Data System (ADS)

    Hu, Baoyu; Feng, Shumin; Nie, Cen

    2017-01-01

    Competition and cooperation is a universal phenomenon in bus transport networks (BTNs) because of the shared stations between bus routes. A measuring method is proposed for competitive and cooperative relationship between bus routes. Based on this measurement, we develop a new representation model for BTNs, namely competitive-cooperative space R. This model is applied to investigate empirically bus transport network of Shenyang (BTN-S) from China. We present the histograms of competitive-cooperative coefficients, competitive coefficients and cooperative coefficients to illustrate that competitive and cooperative relationship plays an important role in transporting passengers. The competitive-cooperative situation shows that cooperative relationship holds an absolutely dominant position in BTN-S. To explore the networked characteristics, we present some empirical distributions, for the number of bus stations on a route, the number of shared stations between two routes, degree and weighted degree, competitive strength, and cooperative strength. We also examine the correlations between degree and competitive strength, and between degree and cooperative strength. Besides, we investigate the diversities of competitive strength and cooperative strength in BTN-S. This study can help us to understand the BTN from a deeper level.

  15. Achieving recommended daily physical activity levels through commuting by public transportation: unpacking individual and contextual influences.

    PubMed

    Wasfi, Rania A; Ross, Nancy A; El-Geneidy, Ahmed M

    2013-09-01

    This paper estimates the amount of daily walking associated with using public transportation in a large metropolitan area and examines individual and contextual characteristics associated with walking distances. Total walking distance to and from transit was calculated from a travel diary survey for 6913 individuals. Multilevel regression modelling was used to examine the underlying factors associated with walking to public transportation. The physical activity benefits of public transportation varied along gender and socio-economic lines. Recommended minutes of daily physical activity can be achieved for public transportation users, especially train users living in affluent suburbs.

  16. 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

  17. 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.

  18. 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.

  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

    DOE PAGES

    Jordan, Amy B.; Stauffer, Philip H.; Knight, Earl E.; ...

    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

  1. 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

  2. 75 FR 25913 - Alternative Transportation in Parks and Public Lands Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-10

    ... Federal Transit Administration Alternative Transportation in Parks and Public Lands Program AGENCY... Lands (ATPPL)) program, authorized by Section 3021 of the Safe, Accountable, Flexible, Efficient... systems in parks and public lands. Federal land management agencies and State, tribal and...

  3. Efficient quantum transport in disordered interacting many-body networks.

    PubMed

    Ortega, Adrian; Stegmann, Thomas; Benet, Luis

    2016-10-01

    The coherent transport of n fermions in disordered networks of l single-particle states connected by k-body interactions is studied. These networks are modeled by embedded Gaussian random matrix ensemble (EGE). The conductance bandwidth and the ensemble-averaged total current attain their maximal values if the system is highly filled n∼l-1 and k∼n/2. For the cases k=1 and k=n the bandwidth is minimal. We show that for all parameters the transport is enhanced significantly whenever centrosymmetric embedded Gaussian ensemble (csEGE) are considered. In this case the transmission shows numerous resonances of perfect transport. Analyzing the transmission by spectral decomposition, we find that centrosymmetry induces strong correlations and enhances the extrema of the distributions. This suppresses destructive interference effects in the system and thus causes backscattering-free transmission resonances that enhance the overall transport. The distribution of the total current for the csEGE has a very large dominating peak for n=l-1, close to the highest observed currents.

  4. Efficient quantum transport in disordered interacting many-body networks

    NASA Astrophysics Data System (ADS)

    Ortega, Adrian; Stegmann, Thomas; Benet, Luis

    2016-10-01

    The coherent transport of n fermions in disordered networks of l single-particle states connected by k -body interactions is studied. These networks are modeled by embedded Gaussian random matrix ensemble (EGE). The conductance bandwidth and the ensemble-averaged total current attain their maximal values if the system is highly filled n ˜l -1 and k ˜n /2 . For the cases k =1 and k =n the bandwidth is minimal. We show that for all parameters the transport is enhanced significantly whenever centrosymmetric embedded Gaussian ensemble (csEGE) are considered. In this case the transmission shows numerous resonances of perfect transport. Analyzing the transmission by spectral decomposition, we find that centrosymmetry induces strong correlations and enhances the extrema of the distributions. This suppresses destructive interference effects in the system and thus causes backscattering-free transmission resonances that enhance the overall transport. The distribution of the total current for the csEGE has a very large dominating peak for n =l -1 , close to the highest observed currents.

  5. Psychosocial and Environmental Correlates of Walking, Cycling, Public Transport and Passive Transport to Various Destinations in Flemish Older Adolescents

    PubMed Central

    Verhoeven, Hannah; Simons, Dorien; Van Dyck, Delfien; Van Cauwenberg, Jelle; Clarys, Peter; De Bourdeaudhuij, Ilse; de Geus, Bas; Vandelanotte, Corneel; Deforche, Benedicte

    2016-01-01

    Background Active transport is a convenient way to incorporate physical activity in adolescents’ daily life. The present study aimed to investigate which psychosocial and environmental factors are associated with walking, cycling, public transport (train, tram, bus, metro) and passive transport (car, motorcycle, moped) over short distances (maximum eight kilometres) among older adolescents (17–18 years), to school and to other destinations. Methods 562 older adolescents completed an online questionnaire assessing socio-demographic variables, psychosocial variables, environmental variables and transport to school/other destinations. Zero-inflated negative binomial regression models were performed. Results More social modelling and a higher residential density were positively associated with walking to school and walking to other destinations, respectively. Regarding cycling, higher self-efficacy and a higher social norm were positively associated with cycling to school and to other destinations. Regarding public transport, a higher social norm, more social modelling of siblings and/or friends, more social support and a higher land use mix access were positively related to public transport to school and to other destinations, whereas a greater distance to school only related positively to public transport to school. Regarding passive transport, more social support and more perceived benefits were positively associated with passive transport to school and to other destinations. Perceiving less walking and cycling facilities at school was positively related to passive transport to school only, and more social modelling was positively related to passive transport to other destinations. Conclusions Overall, psychosocial variables seemed to be more important than environmental variables across the four transport modes. Social norm, social modelling and social support were the most consistent psychosocial factors which indicates that it is important to target both

  6. 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

  7. 77 FR 66588 - Development of the Nationwide Interoperable Public Safety Broadband Network

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-06

    ... Interoperable Public Safety Broadband Network AGENCY: National Telecommunications and Information Administration... meeting of the First Responder Network Authority (FirstNet) as well as to invite input on other network.../comments-nationwide-interoperable-public-safety-broadband-network-noi . All personal...

  8. Predicting the use of public transportation: a case study from Putrajaya, Malaysia.

    PubMed

    Borhan, Muhamad Nazri; Syamsunur, Deprizon; Akhir, Norliza Mohd; Yazid, Muhamad Razuhanafi Mat; Ismail, Amiruddin; Rahmat, Riza Atiq

    2014-01-01

    Putrajaya is a new federal administrative capital of Malaysia which has been set to achieve a 70% share of all travels by public transport in the city area. However, the current modal split between the public transport and private transport is 15:85. In order to understand travelers' willingness to use the public transport, a conceptual model has been developed to determine the factors that affect them to use the public transport instead of travelling in their own cars. Various variables such as service quality, environmental impact, attitude, and behavior intention were analyzed and tested using structural equation model (SEM). Results indicate that the service quality and attitude are found to have positive effects on the behavioral intention of taking the public transport. Other than this, this study also shows that the service quality and environmental impact have some positive influences on the attitude to using the public transport. However, environmental impact has no significant, positive, and direct effect on behavioral intention. The results of this study demonstrate that the model that was developed is useful in predicting the public transport and it could provide a more complete understanding of behavioral intention towards public transport use.

  9. Predicting the Use of Public Transportation: A Case Study from Putrajaya, Malaysia

    PubMed Central

    Borhan, Muhamad Nazri; Mohd Akhir, Norliza; Mat Yazid, Muhamad Razuhanafi; Ismail, Amiruddin; Rahmat, Riza Atiq

    2014-01-01

    Putrajaya is a new federal administrative capital of Malaysia which has been set to achieve a 70% share of all travels by public transport in the city area. However, the current modal split between the public transport and private transport is 15 : 85. In order to understand travelers' willingness to use the public transport, a conceptual model has been developed to determine the factors that affect them to use the public transport instead of travelling in their own cars. Various variables such as service quality, environmental impact, attitude, and behavior intention were analyzed and tested using structural equation model (SEM). Results indicate that the service quality and attitude are found to have positive effects on the behavioral intention of taking the public transport. Other than this, this study also shows that the service quality and environmental impact have some positive influences on the attitude to using the public transport. However, environmental impact has no significant, positive, and direct effect on behavioral intention. The results of this study demonstrate that the model that was developed is useful in predicting the public transport and it could provide a more complete understanding of behavioral intention towards public transport use. PMID:25110744

  10. Integrative Analysis of the Physical Transport Network into Australia

    PubMed Central

    Cope, Robert C.; Ross, Joshua V.; Wittmann, Talia A.; Prowse, Thomas A. A.; Cassey, Phillip

    2016-01-01

    Effective biosecurity is necessary to protect nations and their citizens from a variety of threats, including emerging infectious diseases, agricultural or environmental pests and pathogens, and illegal wildlife trade. The physical pathways by which these threats are transported internationally, predominantly shipping and air traffic, have undergone significant growth and changes in spatial distributions in recent decades. An understanding of the specific pathways and donor-traffic hotspots created by this integrated physical transport network is vital for the development of effective biosecurity strategies into the future. In this study, we analysed the physical transport network into Australia over the period 1999–2012. Seaborne and air traffic were weighted to calculate a “weighted cumulative impact” score for each source region worldwide, each year. High risk source regions, and those source regions that underwent substantial changes in risk over the study period, were determined. An overall risk ranking was calculated by integrating across all possible weighting combinations. The source regions having greatest overall physical connectedness with Australia were Singapore, which is a global transport hub, and the North Island of New Zealand, a close regional trading partner with Australia. Both those regions with large amounts of traffic across multiple vectors (e.g., Hong Kong), and those with high levels of traffic of only one type (e.g., Bali, Indonesia with respect to passenger flights), were represented among high risk source regions. These data provide a baseline model for the transport of individuals and commodities against which the effectiveness of biosecurity controls may be assessed, and are a valuable tool in the development of future biosecurity policy. PMID:26881782

  11. Integrative Analysis of the Physical Transport Network into Australia.

    PubMed

    Cope, Robert C; Ross, Joshua V; Wittmann, Talia A; Prowse, Thomas A A; Cassey, Phillip

    2016-01-01

    Effective biosecurity is necessary to protect nations and their citizens from a variety of threats, including emerging infectious diseases, agricultural or environmental pests and pathogens, and illegal wildlife trade. The physical pathways by which these threats are transported internationally, predominantly shipping and air traffic, have undergone significant growth and changes in spatial distributions in recent decades. An understanding of the specific pathways and donor-traffic hotspots created by this integrated physical transport network is vital for the development of effective biosecurity strategies into the future. In this study, we analysed the physical transport network into Australia over the period 1999-2012. Seaborne and air traffic were weighted to calculate a "weighted cumulative impact" score for each source region worldwide, each year. High risk source regions, and those source regions that underwent substantial changes in risk over the study period, were determined. An overall risk ranking was calculated by integrating across all possible weighting combinations. The source regions having greatest overall physical connectedness with Australia were Singapore, which is a global transport hub, and the North Island of New Zealand, a close regional trading partner with Australia. Both those regions with large amounts of traffic across multiple vectors (e.g., Hong Kong), and those with high levels of traffic of only one type (e.g., Bali, Indonesia with respect to passenger flights), were represented among high risk source regions. These data provide a baseline model for the transport of individuals and commodities against which the effectiveness of biosecurity controls may be assessed, and are a valuable tool in the development of future biosecurity policy.

  12. Patterning of leaf vein networks by convergent auxin transport pathways.

    PubMed

    Sawchuk, Megan G; Edgar, Alexander; Scarpella, Enrico

    2013-01-01

    The formation of leaf vein patterns has fascinated biologists for centuries. Transport of the plant signal auxin has long been implicated in vein patterning, but molecular details have remained unclear. Varied evidence suggests a central role for the plasma-membrane (PM)-localized PIN-FORMED1 (PIN1) intercellular auxin transporter of Arabidopsis thaliana in auxin-transport-dependent vein patterning. However, in contrast to the severe vein-pattern defects induced by auxin transport inhibitors, pin1 mutant leaves have only mild vein-pattern defects. These defects have been interpreted as evidence of redundancy between PIN1 and the other four PM-localized PIN proteins in vein patterning, redundancy that underlies many developmental processes. By contrast, we show here that vein patterning in the Arabidopsis leaf is controlled by two distinct and convergent auxin-transport pathways: intercellular auxin transport mediated by PM-localized PIN1 and intracellular auxin transport mediated by the evolutionarily older, endoplasmic-reticulum-localized PIN6, PIN8, and PIN5. PIN6 and PIN8 are expressed, as PIN1 and PIN5, at sites of vein formation. pin6 synthetically enhances pin1 vein-pattern defects, and pin8 quantitatively enhances pin1pin6 vein-pattern defects. Function of PIN6 is necessary, redundantly with that of PIN8, and sufficient to control auxin response levels, PIN1 expression, and vein network formation; and the vein pattern defects induced by ectopic PIN6 expression are mimicked by ectopic PIN8 expression. Finally, vein patterning functions of PIN6 and PIN8 are antagonized by PIN5 function. Our data define a new level of control of vein patterning, one with repercussions on other patterning processes in the plant, and suggest a mechanism to select cell files specialized for vascular function that predates evolution of PM-localized PIN proteins.

  13. Sediment transport mechanisms through the sustainable vegetated flow networks

    NASA Astrophysics Data System (ADS)

    Allen, Deonie; Haynes, Heather; Arthur, Scott

    2016-04-01

    Understanding the pollution treatment efficiency of a sustainable urban drainage (SuDS) asset or network requires the influx, transport, detention and discharge of the pollutant within the system. To date event specific monitoring of sediment (primarily total suspended solids) concentrations in the inflow and discharge from SuDS have been monitored. Long term analysis of where the sediment is transported to and the residency time of this pollutant within the SuDS asset or network have not been unraveled due to the difficulty in monitoring specific sediment particulate movement. Using REO tracing methodology, sediment particulate movement has become possible. In tracing sediment movement from an urban surface the internal residency and transportation of this sediment has illustrated SuDS asset differences in multi-event detention. Of key importance is the finding that sediment remains within the SuDS asset for extended periods of time, but that the location sediment detention changes. Thus, over multiple rainfall-runoff events sediment is seen to move through the SuDS assets and network proving the assumption that detained sediment is permanent and stationary to be inaccurate. Furthermore, mass balance analysis of SuDS sediment indicates that there is notable re-suspension and ongoing release of sediment from the SuDS over time and cumulative rainfall-runoff events. Continued monitoring of sediment deposition and concentration in suspension illustrates that sediment detention within SuDS decreases over time/multiple events, without stabilizing within a 12 month period. Repeated experiments show a consistent pattern of detention and release for the three SuDS networks monitored in Scotland. Through consideration of both rainfall and flow factors the drivers of sediment transport within the monitored SuDS have been identified. Within the limitation of this field study the key drivers to SuDS sediment detention efficiency (or transport of sediment through the system

  14. Sailor: Maryland's Online Public Information Network. Sailor Network Assessment Final Report Compendium.

    ERIC Educational Resources Information Center

    Bertot, John Carlo; McClure, Charles R.

    This compendium is a companion document to the Maryland Sailor Online Public Information Network assessment final report, and contains detailed study findings, study data collection activity write-ups, detailed methodologies, data collection tools, and consultant notes on the uses of the study's data collection instruments. The purpose of the…

  15. Random walk approach for dispersive transport in pipe networks

    NASA Astrophysics Data System (ADS)

    Sämann, Robert; Graf, Thomas; Neuweiler, Insa

    2016-04-01

    Keywords: particle transport, random walk, pipe, network, HYSTEM-EXTAN, OpenGeoSys After heavy pluvial events in urban areas the available drainage system may be undersized at peak flows (Fuchs, 2013). Consequently, rainwater in the pipe network is likely to spill out through manholes. The presence of hazardous contaminants in the pipe drainage system represents a potential risk to humans especially when the contaminated drainage water reaches the land surface. Real-time forecasting of contaminants in the drainage system needs a quick calculation. Numerical models to predict the fate of contaminants are usually based on finite volume methods. Those are not applicable here because of their volume averaging elements. Thus, a more efficient method is preferable, which is independent from spatial discretization. In the present study, a particle-based method is chosen to calculate transport paths and spatial distribution of contaminants within a pipe network. A random walk method for particles in turbulent flow in partially filled pipes has been developed. Different approaches for in-pipe-mixing and node-mixing with respect to the geometry in a drainage network are shown. A comparison of dispersive behavior and calculation time is given to find the fastest model. The HYSTEM-EXTRAN (itwh, 2002) model is used to provide hydrodynamic conditions in the pipe network according to surface runoff scenarios in order to real-time predict contaminant transport in an urban pipe network system. The newly developed particle-based model will later be coupled to the subsurface flow model OpenGeoSys (Kolditz et al., 2012). References: Fuchs, L. (2013). Gefährdungsanalyse zur Überflutungsvorsorge kommunaler Entwässerungssysteme. Sanierung und Anpassung von Entwässerungssystemen-Alternde Infrastruktur und Klimawandel, Österreichischer Wasser-und Abfallwirtschaftsverband, Wien, ISBN, 978-3. itwh (2002). Modellbeschreibung, Institut für technisch-wissenschaftliche Hydrologie Gmb

  16. Transportation and the Environment. Publication No. 74-2.

    ERIC Educational Resources Information Center

    Fagan, James S.

    The increasingly important role of transportation and its environmental impact is given major emphasis in this curriculum unit for secondary students. Four purposes of this unit are to describe and show (1) the historical development of transportation in America; (2) the effect of current transportation practices upon the environment; (3) some…

  17. 76 FR 12305 - Extension of Public Comment Period for Proposed Action on Interstate Transport of Pollution...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-07

    ... AGENCY 40 CFR Part 52 Extension of Public Comment Period for Proposed Action on Interstate Transport of..., 2011, EPA published in the Federal Register a proposed rule on interstate transport of pollution... requested comment by March 7, 2011. EPA is extending the public comment period for the proposed rule...

  18. Vehicles for Education: Turkish Students' Beliefs and Views about Public Transport

    ERIC Educational Resources Information Center

    Kilinc, Ahmet; Seymen, Hatice; Malandrakis, George; Boyes, Edward; Stanisstreet, Martin

    2013-01-01

    The increasing use of private rather than public transport is impacting on the environment in a number of ways, including contributing to the major problem of global warming. It is necessary, therefore, to improve strategies to encourage greater use of public transport. The aim of this study is to explore which perceived aspects of public…

  19. 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

  20. Universal scaling of optimal current distribution in transportation networks.

    PubMed

    Simini, Filippo; Rinaldo, Andrea; Maritan, Amos

    2009-04-01

    Transportation networks are inevitably selected with reference to their global cost which depends on the strengths and the distribution of the embedded currents. We prove that optimal current distributions for a uniformly injected d -dimensional network exhibit robust scale-invariance properties, independently of the particular cost function considered, as long as it is convex. We find that, in the limit of large currents, the distribution decays as a power law with an exponent equal to (2d-1)/(d-1). The current distribution can be exactly calculated in d=2 for all values of the current. Numerical simulations further suggest that the scaling properties remain unchanged for both random injections and by randomizing the convex cost functions.

  1. Climate and change: simulating flooding impacts on urban transport network

    NASA Astrophysics Data System (ADS)

    Pregnolato, Maria; Ford, Alistair; Dawson, Richard

    2015-04-01

    National-scale climate projections indicate that in the future there will be hotter and drier summers, warmer and wetter winters, together with rising sea levels. The frequency of extreme weather events is expected to increase, causing severe damage to the built environment and disruption of infrastructures (Dawson, 2007), whilst population growth and changed demographics are placing new demands on urban infrastructure. It is therefore essential to ensure infrastructure networks are robust to these changes. This research addresses these challenges by focussing on the development of probabilistic tools for managing risk by modelling urban transport networks within the context of extreme weather events. This paper presents a methodology to investigate the impacts of extreme weather events on urban environment, in particular infrastructure networks, through a combination of climate simulations and spatial representations. By overlaying spatial data on hazard thresholds from a flood model and a flood safety function, mitigated by potential adaptation strategies, different levels of disruption to commuting journeys on road networks are evaluated. The method follows the Catastrophe Modelling approach and it consists of a spatial model, combining deterministic loss models and probabilistic risk assessment techniques. It can be applied to present conditions as well as future uncertain scenarios, allowing the examination of the impacts alongside socio-economic and climate changes. The hazard is determined by simulating free surface water flooding, with the software CityCAT (Glenis et al., 2013). The outputs are overlapped to the spatial locations of a simple network model in GIS, which uses journey-to-work (JTW) observations, supplemented with speed and capacity information. To calculate the disruptive effect of flooding on transport networks, a function relating water depth to safe driving car speed has been developed by combining data from experimental reports (Morris et

  2. Scattering and transport properties of tight-binding random networks

    NASA Astrophysics Data System (ADS)

    Martínez-Mendoza, A. J.; Alcazar-López, A.; Méndez-Bermúdez, J. A.

    2013-07-01

    We study numerically scattering and transport statistical properties of tight-binding random networks characterized by the number of nodes N and the average connectivity α. We use a scattering approach to electronic transport and concentrate on the case of a small number of single-channel attached leads. We observe a smooth crossover from insulating to metallic behavior in the average scattering matrix elements <|Smn|2>, the conductance probability distribution w(T), the average conductance , the shot noise power P, and the elastic enhancement factor F by varying α from small (α→0) to large (α→1) values. We also show that all these quantities are invariant for fixed ξ=αN. Moreover, we proposes a heuristic and universal relation between <|Smn|2>, , and P and the disorder parameter ξ.

  3. An integrated GIS-based data model for multimodal urban public transportation analysis and management

    NASA Astrophysics Data System (ADS)

    Chen, Shaopei; Tan, Jianjun; Ray, C.; Claramunt, C.; Sun, Qinqin

    2008-10-01

    Diversity is one of the main characteristics of transportation data collected from multiple sources or formats, which can be extremely complex and disparate. Moreover, these multimodal transportation data are usually characterised by spatial and temporal properties. Multimodal transportation network data modelling involves both an engineering and research domain that has attracted the design of a number of spatio-temporal data models in the geographic information system (GIS). However, the application of these specific models to multimodal transportation network is still a challenging task. This research addresses this challenge from both integrated multimodal data organization and object-oriented modelling perspectives, that is, how a complex urban transportation network should be organized, represented and modeled appropriately when considering a multimodal point of view, and using object-oriented modelling method. We proposed an integrated GIS-based data model for multimodal urban transportation network that lays a foundation to enhance the multimodal transportation network analysis and management. This modelling method organizes and integrates multimodal transit network data, and supports multiple representations for spatio-temporal objects and relationship as both visual and graphic views. The data model is expressed by using a spatio-temporal object-oriented modelling method, i.e., the unified modelling language (UML) extended to spatial and temporal plug-in for visual languages (PVLs), which provides an essential support to the spatio-temporal data modelling for transportation GIS.

  4. An Algorithm for the Mixed Transportation Network Design Problem.

    PubMed

    Liu, Xinyu; Chen, Qun

    2016-01-01

    This paper proposes an optimization algorithm, the dimension-down iterative algorithm (DDIA), for solving a mixed transportation network design problem (MNDP), which is generally expressed as a mathematical programming with equilibrium constraint (MPEC). The upper level of the MNDP aims to optimize the network performance via both the expansion of the existing links and the addition of new candidate links, whereas the lower level is a traditional Wardrop user equilibrium (UE) problem. The idea of the proposed solution algorithm (DDIA) is to reduce the dimensions of the problem. A group of variables (discrete/continuous) is fixed to optimize another group of variables (continuous/discrete) alternately; then, the problem is transformed into solving a series of CNDPs (continuous network design problems) and DNDPs (discrete network design problems) repeatedly until the problem converges to the optimal solution. The advantage of the proposed algorithm is that its solution process is very simple and easy to apply. Numerical examples show that for the MNDP without budget constraint, the optimal solution can be found within a few iterations with DDIA. For the MNDP with budget constraint, however, the result depends on the selection of initial values, which leads to different optimal solutions (i.e., different local optimal solutions). Some thoughts are given on how to derive meaningful initial values, such as by considering the budgets of new and reconstruction projects separately.

  5. An Algorithm for the Mixed Transportation Network Design Problem

    PubMed Central

    Liu, Xinyu; Chen, Qun

    2016-01-01

    This paper proposes an optimization algorithm, the dimension-down iterative algorithm (DDIA), for solving a mixed transportation network design problem (MNDP), which is generally expressed as a mathematical programming with equilibrium constraint (MPEC). The upper level of the MNDP aims to optimize the network performance via both the expansion of the existing links and the addition of new candidate links, whereas the lower level is a traditional Wardrop user equilibrium (UE) problem. The idea of the proposed solution algorithm (DDIA) is to reduce the dimensions of the problem. A group of variables (discrete/continuous) is fixed to optimize another group of variables (continuous/discrete) alternately; then, the problem is transformed into solving a series of CNDPs (continuous network design problems) and DNDPs (discrete network design problems) repeatedly until the problem converges to the optimal solution. The advantage of the proposed algorithm is that its solution process is very simple and easy to apply. Numerical examples show that for the MNDP without budget constraint, the optimal solution can be found within a few iterations with DDIA. For the MNDP with budget constraint, however, the result depends on the selection of initial values, which leads to different optimal solutions (i.e., different local optimal solutions). Some thoughts are given on how to derive meaningful initial values, such as by considering the budgets of new and reconstruction projects separately. PMID:27626803

  6. Modeling Tokamak Transport with Neural-Network Based Models

    NASA Astrophysics Data System (ADS)

    Meneghini, O.; Luna, C.; Penna, J.; Smith, S. P.; Lao, L. L.

    2014-10-01

    This work uses neural networks (NNs) as a means to extract information from the massive volume of aggregated data that are available either from experiments or from simulation databases, and distill an accurate transport model for the heat, particle, and momentum transport fluxes as a function of local dimensionless plasma parameters. The resulting model has been benchmarked with over 4000 DIII-D plasmas in different regimes, and it is able to capture the experimental behavior inside of ρ < 0 . 95 with average error <20% for all transport channels. The NN model was embedded into the ONETWO transport code and is now being used to develop time-dependent scenarios in support of DIII-D operations. The simulated temperature, density and rotation profiles closely match the experimental measurements, and a stiff response of the heat fluxes has been observed in the model for increasing source power. The numerical efficiency of the NN approach makes it ideal for real time plasma control and scenario preparation for current experiments and for ITER. Work supported in part by the US DOE under DE-FG02-95ER54309 and DE-FC02-04ER54698.

  7. Centrosymmetry enhances quantum transport in disordered molecular networks

    NASA Astrophysics Data System (ADS)

    Zech, Tobias; Mulet, Roberto; Wellens, Thomas; Buchleitner, Andreas

    2014-05-01

    For more than 50 years we have known that photosynthetic systems harvest solar energy with almost unit quantum efficiency. However, recent experimental evidence of quantum coherence during the excitonic energy transport in photosynthetic organisms challenges our understanding of this fundamental biological function. Currently, and despite numerous efforts, the causal connection between coherence and efficiency is still a matter of debate. We show, through extensive simulations of quantum coherent transport on networks, that three dimensional structures characterized by centro-symmetric Hamiltonians are statistically more efficient than random arrangements. Moreover, a strong correlation of centro-symmetry with quantum efficiency is also observed under the coherent transport dynamics induced by experimentally estimated electronic Hamiltonians of the Fenna-Mathew-Olson complex of sulfur bacteria and of the cryptophyte PC645 complex of marine algae. The application of a genetic algorithm results in a set of optimized Hamiltonians only when seeded from the experimentally estimated Hamiltonian. These results suggest that what appears to be geometrically disordered complexes may well exhibit an inherent hidden symmetry which enhances the energy transport between chromophores. We are confident that our results will motivate research to explore the properties of nearly centro-symmetric Hamiltonians in realistic environments, and to unveil the role of symmetries for quantum effects in biology. The unravelling of such symmetries may open novel perspectives and suggest new design principles in the development of artificial devices.

  8. Investigating water transport through the xylem network in vascular plants.

    PubMed

    Kim, Hae Koo; Park, Joonghyuk; Hwang, Ildoo

    2014-04-01

    Our understanding of physical and physiological mechanisms depends on the development of advanced technologies and tools to prove or re-evaluate established theories, and test new hypotheses. Water flow in land plants is a fascinating phenomenon, a vital component of the water cycle, and essential for life on Earth. The cohesion-tension theory (CTT), formulated more than a century ago and based on the physical properties of water, laid the foundation for our understanding of water transport in vascular plants. Numerous experimental tools have since been developed to evaluate various aspects of the CTT, such as the existence of negative hydrostatic pressure. This review focuses on the evolution of the experimental methods used to study water transport in plants, and summarizes the different ways to investigate the diversity of the xylem network structure and sap flow dynamics in various species. As water transport is documented at different scales, from the level of single conduits to entire plants, it is critical that new results be subjected to systematic cross-validation and that findings based on different organs be integrated at the whole-plant level. We also discuss the functional trade-offs between optimizing hydraulic efficiency and maintaining the safety of the entire transport system. Furthermore, we evaluate future directions in sap flow research and highlight the importance of integrating the combined effects of various levels of hydraulic regulation.

  9. [Local public health networks. Apropos of an experience].

    PubMed

    Guix, Joan; Bocio, Ana; Ferràs, Joaquim; Margalef, Jordi; Osanz, Anna C; Serrano, Mónica; Sentenà, Anna

    2013-01-01

    Public health action on a territory is complex and requires the involvement of multiple actors, who do not always act coordinately. Networks of organizations structures including the whole of the local actors facilitate the generation of synergies and enable greater effectiveness and efficiency of the joint action from the different actors on a same landscape. We present 3 years experience of four Public Health Committees in a region of Catalonia (Spain), composed by the main actors in public health planning. Each of the committees is organized on a plenary and working groups on issues arising from the regional health diagnosis, and coincident with the Health Plan of the Region. Coordination in no case implies the loss or dilution of the firm of the actor generator of intervention initiative in public health, but their empowerment and collaboration by the other actors. In conclusion welcomes the creation of a culture of collaboration and synergies between the different organizations concerned. Lack of specificity is observed in establishing operational objectives, and the need for greater coordination and involvement of the components of the various working groups.

  10. Publication of topographic atlas and control network of Mars

    NASA Technical Reports Server (NTRS)

    Wu, Sherman S. C.; Billideau, Jennifer S.; Spare, Beth A.

    1991-01-01

    To aid planetary studies and the planning of future Mars missions, the Topographic Atlas and Control Network for Mars will be submitted by the end of fiscal year 1992 for publication as a NASA Special Publication. It will consist of reduced versions of 108 1:2 million-scale photomosaics that show contour lines from topographic maps at the same scale, as well as precisely located control points. The control points are from the planetwide network, which is not only instrumental in the compilation of maps at various scales, but is also widely used in other research such as studies of Mars' gravity and atmosphere. An example, a combination of MC 8-NW and -SW, of the photomosaics to be included in the atlas is presented. Contour lines in the figure are at 1-km intervals. The final adjusted ground coordinates and elevations of the 77 control points shown are given in table form. The last column in the table lists the topographic datum (zero elevation) that can be used to compute the solid radius of the control point from the center of mass of Mars. The atlas will also include information such as the adjusted C-matrices of each image, descriptions of the methods used, and their accuracy, and guidelines for users.

  11. Publication patterns in developmental psychology: Trends and social networks.

    PubMed

    Dobermann, Darja; Hamilton, Ian S

    2015-08-27

    Interest in publication patterns has been steady. Journals have instituted policies in an effort to curb bias and provide globally representative research. This study aimed to examine if publication patterns were present in two developmental psychology journals. It also explored the social networks of prominent authors and the prevalence of informal author-editor relationships, searching for any potential power groups. Data were taken from empirical articles published between 2005 and 2014 in Child Development (CD) and The International Journal of Early Childhood (IJEC) data points were geographical authorship affiliation, informal author relationships as established by co-publishing, and connections to journal editors via identical affiliation. Results confirmed the previously established North American dominance in published research. In CD a strongly interlinked social network was identified between authors over the 10 years, with 15 chief influentialists binding groups of authors together. Results suggest that patterns are still present in published research in the realm of developmental psychology. To conclude, the potential implications of these patterns within developmental psychology are presented.

  12. Platelet Serotonin Transporter Function Predicts Default-Mode Network Activity

    PubMed Central

    Kasess, Christian H.; Meyer, Bernhard M.; Hofmaier, Tina; Diers, Kersten; Bartova, Lucie; Pail, Gerald; Huf, Wolfgang; Uzelac, Zeljko; Hartinger, Beate; Kalcher, Klaudius; Perkmann, Thomas; Haslacher, Helmuth; Meyer-Lindenberg, Andreas; Kasper, Siegfried; Freissmuth, Michael; Windischberger, Christian; Willeit, Matthäus; Lanzenberger, Rupert; Esterbauer, Harald; Brocke, Burkhard; Moser, Ewald; Sitte, Harald H.; Pezawas, Lukas

    2014-01-01

    Background The serotonin transporter (5-HTT) is abundantly expressed in humans by the serotonin transporter gene SLC6A4 and removes serotonin (5-HT) from extracellular space. A blood-brain relationship between platelet and synaptosomal 5-HT reuptake has been suggested, but it is unknown today, if platelet 5-HT uptake can predict neural activation of human brain networks that are known to be under serotonergic influence. Methods A functional magnetic resonance study was performed in 48 healthy subjects and maximal 5-HT uptake velocity (Vmax) was assessed in blood platelets. We used a mixed-effects multilevel analysis technique (MEMA) to test for linear relationships between whole-brain, blood-oxygen-level dependent (BOLD) activity and platelet Vmax. Results The present study demonstrates that increases in platelet Vmax significantly predict default-mode network (DMN) suppression in healthy subjects independent of genetic variation within SLC6A4. Furthermore, functional connectivity analyses indicate that platelet Vmax is related to global DMN activation and not intrinsic DMN connectivity. Conclusion This study provides evidence that platelet Vmax predicts global DMN activation changes in healthy subjects. Given previous reports on platelet-synaptosomal Vmax coupling, results further suggest an important role of neuronal 5-HT reuptake in DMN regulation. PMID:24667541

  13. Electron transport in micro to nanoscale solid state networks

    NASA Astrophysics Data System (ADS)

    Fairbanks, Matthew Stetson

    This dissertation focuses on low-dimensional electron transport phenomena in devices ranging from semiconductor electron 'billiards' to semimetal atomic clusters to gold nanoparticles. In each material system, the goal of this research is to understand how carrier transport occurs when many elements act in concert. In the semiconductor electron billiards, magnetoconductance fluctuations, the result of electron quantum interference within the device, are used as a probe of electron transport through arrays of one, two, and three connected billiards. By combining two established analysis techniques, this research demonstrates a novel method for determining the quantum energy level spacing in each of the arrays. That information in turn shows the extent (and limits) of the phase-coherent electron wavefunction in each of the devices. The use of the following two material systems, the semimetal atomic clusters and the gold nanoparticles, is inspired by the electron billiard results. First, the output of the simple, rectangular electron billiards, the magnetoconductance fluctuations, is quite generally found to be fractal. This research addresses the question of what output one might expect from a device with manifestly fractal geometry by simulating the electrical response of fractal resistor networks and by outlining a method to implement such devices in fractal aggregates of semimetal atomic clusters. Second, in gold nanoparticle arrays, the number of array elements can increase by orders of magnitude over the billiard arrays, all with the potential to stay in a similar, phase-coherent transport regime. The last portion of this dissertation details the fabrication of these nanoparticle-based devices and their electrical characteristics, which exhibit strong evidence for electron transport in the Coulomb-blockade regime. A sketch for further 'off-blockade' experiments to realize magnetoconductance fluctuations, i.e. phase-coherent electron phenomena, is presented.

  14. Costs and benefits of employment transportation for low-wage workers: an assessment of job access public transportation services.

    PubMed

    Thakuriah Vonu, Piyushimita; Persky, Joseph; Soot, Siim; Sriraj, P S

    2013-04-01

    This paper focuses on an evaluation of public transportation-based employment transportation (ET) services to transport low-wage workers to jobs in the US. We make an attempt to capture a more comprehensive range of intended and unintended outcomes of ET services than those traditionally considered in the case of public transportation services. Using primary data from 23 locations across the country, we present a framework to evaluate how transportation improvements, in interaction with labor markets, can affect users' short-run economic welfare, users' long-run human capital accumulation and non-users' short-run economic welfare. These services were partially funded by a specialized program - the Job Access and Reverse Commute (JARC) program - which was consolidated into larger transit funding programs by recent legislation. In the sites examined, we found that low wage users benefited from self-reported increased access to jobs, improvements in earnings potential, as well as from savings in transport cost and time. Simulations show the potential of users to accrue long-term worklife benefits. At the same time, users may have accrued changes in leisure time as a result of transitioning from unemployment to employment, and generated a range of societal impacts on three classes of non-users: the general tax-paying public, the general commuting public in the service operating area and other low-wage workers in local labor markets.

  15. Physical Activity Associated with Public Transport Use—A Review and Modelling of Potential Benefits

    PubMed Central

    Rissel, Chris; Curac, Nada; Greenaway, Mark; Bauman, Adrian

    2012-01-01

    Active travel, particularly walking and cycling, has been recommended because of the health benefits associated with increased physical activity. Use of public transport generally involves some walking to bus stops or train stations. This paper is a systematic review of how much time is spent in physical activity among adults using public transport. It also explores the potential effect on the population level of physical activity if inactive adults in NSW, Australia, increased their walking through increased use of public transport. Of 1,733 articles, 27 met the search criteria, and nine reported on absolute measures of physical activity associated with public transport. A further 18 papers reported on factors associated with physical activity as part of public transport use. A range of 8–33 additional minutes of walking was identified from this systematic search as being attributable to public transport use. Using “bootstrapping” statistical modelling, if 20% of all inactive adults increased their walking by only 16 minutes a day for five days a week, we predict there would be a substantial 6.97% increase in the proportion of the adult population considered “sufficiently active”. More minutes walked per day, or a greater uptake of public transport by inactive adults would likely lead to significantly greater increases in the adult population considered sufficiently active. PMID:22851954

  16. Physical activity associated with public transport use--a review and modelling of potential benefits.

    PubMed

    Rissel, Chris; Curac, Nada; Greenaway, Mark; Bauman, Adrian

    2012-07-01

    Active travel, particularly walking and cycling, has been recommended because of the health benefits associated with increased physical activity. Use of public transport generally involves some walking to bus stops or train stations. This paper is a systematic review of how much time is spent in physical activity among adults using public transport. It also explores the potential effect on the population level of physical activity if inactive adults in NSW, Australia, increased their walking through increased use of public transport. Of 1,733 articles, 27 met the search criteria, and nine reported on absolute measures of physical activity associated with public transport. A further 18 papers reported on factors associated with physical activity as part of public transport use. A range of 8-33 additional minutes of walking was identified from this systematic search as being attributable to public transport use. Using "bootstrapping" statistical modelling, if 20% of all inactive adults increased their walking by only 16 minutes a day for five days a week, we predict there would be a substantial 6.97% increase in the proportion of the adult population considered "sufficiently active". More minutes walked per day, or a greater uptake of public transport by inactive adults would likely lead to significantly greater increases in the adult population considered sufficiently active.

  17. Density-based and transport-based core-periphery structures in networks

    NASA Astrophysics Data System (ADS)

    Lee, Sang Hoon; Cucuringu, Mihai; Porter, Mason A.

    2014-03-01

    Networks often possess mesoscale structures, and studying them can yield insights into both structure and function. It is most common to study community structure, but numerous other types of mesoscale structures also exist. In this paper, we examine core-periphery structures based on both density and transport. In such structures, core network components are well-connected both among themselves and to peripheral components, which are not well-connected to anything. We examine core-periphery structures in a wide range of examples of transportation, social, and financial networks—including road networks in large urban areas, a rabbit warren, a dolphin social network, a European interbank network, and a migration network between counties in the United States. We illustrate that a recently developed transport-based notion of node coreness is very useful for characterizing transportation networks. We also generalize this notion to examine core versus peripheral edges, and we show that the resulting diagnostic is also useful for transportation networks. To examine the properties of transportation networks further, we develop a family of generative models of roadlike networks. We illustrate the effect of the dimensionality of the embedding space on transportation networks, and we demonstrate that the correlations between different measures of coreness can be very different for different types of networks.

  18. A Systems Approach to Scalable Transportation Network Modeling

    SciTech Connect

    Perumalla, Kalyan S

    2006-01-01

    Emerging needs in transportation network modeling and simulation are raising new challenges with respect to scal-ability of network size and vehicular traffic intensity, speed of simulation for simulation-based optimization, and fidel-ity of vehicular behavior for accurate capture of event phe-nomena. Parallel execution is warranted to sustain the re-quired detail, size and speed. However, few parallel simulators exist for such applications, partly due to the challenges underlying their development. Moreover, many simulators are based on time-stepped models, which can be computationally inefficient for the purposes of modeling evacuation traffic. Here an approach is presented to de-signing a simulator with memory and speed efficiency as the goals from the outset, and, specifically, scalability via parallel execution. The design makes use of discrete event modeling techniques as well as parallel simulation meth-ods. Our simulator, called SCATTER, is being developed, incorporating such design considerations. Preliminary per-formance results are presented on benchmark road net-works, showing scalability to one million vehicles simu-lated on one processor.

  19. Modeling of transport phenomena in tokamak plasmas with neural networks

    NASA Astrophysics Data System (ADS)

    Meneghini, O.; Luna, C. J.; Smith, S. P.; Lao, L. L.

    2014-06-01

    A new transport model that uses neural networks (NNs) to yield electron and ion heat flux profiles has been developed. Given a set of local dimensionless plasma parameters similar to the ones that the highest fidelity models use, the NN model is able to efficiently and accurately predict the ion and electron heat transport profiles. As a benchmark, a NN was built, trained, and tested on data from the 2012 and 2013 DIII-D experimental campaigns. It is found that NN can capture the experimental behavior over the majority of the plasma radius and across a broad range of plasma regimes. Although each radial location is calculated independently from the others, the heat flux profiles are smooth, suggesting that the solution found by the NN is a smooth function of the local input parameters. This result supports the evidence of a well-defined, non-stochastic relationship between the input parameters and the experimentally measured transport fluxes. The numerical efficiency of this method, requiring only a few CPU-μs per data point, makes it ideal for scenario development simulations and real-time plasma control.

  20. Modeling of transport phenomena in tokamak plasmas with neural networks

    SciTech Connect

    Meneghini, O.; Luna, C. J.; Smith, S. P.; Lao, L. L.

    2014-06-15

    A new transport model that uses neural networks (NNs) to yield electron and ion heat flux profiles has been developed. Given a set of local dimensionless plasma parameters similar to the ones that the highest fidelity models use, the NN model is able to efficiently and accurately predict the ion and electron heat transport profiles. As a benchmark, a NN was built, trained, and tested on data from the 2012 and 2013 DIII-D experimental campaigns. It is found that NN can capture the experimental behavior over the majority of the plasma radius and across a broad range of plasma regimes. Although each radial location is calculated independently from the others, the heat flux profiles are smooth, suggesting that the solution found by the NN is a smooth function of the local input parameters. This result supports the evidence of a well-defined, non-stochastic relationship between the input parameters and the experimentally measured transport fluxes. The numerical efficiency of this method, requiring only a few CPU-μs per data point, makes it ideal for scenario development simulations and real-time plasma control.

  1. Electron transport in multiterminal networks of Majorana bound states

    NASA Astrophysics Data System (ADS)

    Weithofer, Luzie; Recher, Patrik; Schmidt, Thomas L.

    2014-11-01

    We investigate electron transport through multiterminal networks hosting Majorana bound states (MBS) in the framework of full counting statistics. In particular, we apply our general results to T-shaped junctions of two Majorana nanowires. When the wires are in the topologically nontrivial regime, three MBS are localized near the outer ends of the wires, while one MBS is localized near the crossing point, and when the lengths of the wires are finite adjacent MBS can overlap. We propose a combination of current and cross-correlation measurements to reveal the predicted coupling of four Majoranas in a topological T junction. Interestingly, we show that the elementary transport processes at the central lead are different compared to the outer leads, giving rise to characteristic nonlocal signatures in electronic transport. We find quantitative agreement between our analytical model and numerical simulations of a tight-binding model. Using the numerical simulations, we discuss the effect of weak disorder on the current and the cross-correlation functions.

  2. Meeting Public Expectations through Networks: The Collaborative Advantage of a Multi-Institutional Teaching Center

    ERIC Educational Resources Information Center

    Kihl, Brenda Kay

    2010-01-01

    In a world of complex problems, where public funding is decreasing and demand for public services is increasing, public entities are turning to collaborative networks to find solutions. This dissertation explores the development of one such network in Collin County, Texas. The researcher presents a case study describing and analyzing the…

  3. Role of public transport in accessibility to emergency dental care in Melbourne, Australia.

    PubMed

    Rocha, Carla M; Kruger, Estie; McGuire, Shane; Tennant, Marc

    2015-01-01

    The aim of this study was to develop a method for the analysis of the influence of public transport supply in a large city (Melbourne) on the access to emergency dental treatment. Geographic Information Systems (GIS) tools were used to associate the geographical distribution of patients (and their socioeconomic status) with accessibility (through public transport supply, i.e. bus, tram and/or train) to emergency dental care. The methodology used allowed analysis of the socioeconomic status of patient residential areas and both spatial location and supply frequency of public transport by using existing data from patient records, census and transport departments. In metropolitan Melbourne, a total of 13 784 patients met the inclusion criteria for the study sample, of which 95% (n = 13 077) were living within a 50 km radius of the Royal Dental Hospital of Melbourne. Low socioeconomic areas had a higher demand for dental emergency care in the Royal Dental Hospital of Melbourne. Public transport supply was similar across the various socioeconomic strata in the population, with 80% of patients having good access to public transport. However, when considering only high-frequency bus stops, the percentage of patients living within 400 m from a bus stop dropped to 65%. Despite this, the number of patients (adjusted to the population) coming from areas not supplied by public transport, and from areas with good or poor public transport supply, was similar. The methodology applied in the present study highlights the importance of evaluating not only the spatial distribution but also the frequency of public transport supply when studying access to services. This methodology can be extrapolated to other settings to identity transport/access patterns for a variety of services.

  4. Cross-layer restoration with software defined networking based on IP over optical transport networks

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Cheng, Lei; Deng, Junni; Zhao, Yongli; Zhang, Jie; Lee, Young

    2015-10-01

    The IP over optical transport network is a very promising networking architecture applied to the interconnection of geographically distributed data centers due to the performance guarantee of low delay, huge bandwidth and high reliability at a low cost. It can enable efficient resource utilization and support heterogeneous bandwidth demands in highly-available, cost-effective and energy-effective manner. In case of cross-layer link failure, to ensure a high-level quality of service (QoS) for user request after the failure becomes a research focus. In this paper, we propose a novel cross-layer restoration scheme for data center services with software defined networking based on IP over optical network. The cross-layer restoration scheme can enable joint optimization of IP network and optical network resources, and enhance the data center service restoration responsiveness to the dynamic end-to-end service demands. We quantitatively evaluate the feasibility and performances through the simulation under heavy traffic load scenario in terms of path blocking probability and path restoration latency. Numeric results show that the cross-layer restoration scheme improves the recovery success rate and minimizes the overall recovery time.

  5. Potential health impact of switching from car to public transportation when commuting to work.

    PubMed

    Morabia, Alfredo; Mirer, Franklin E; Amstislavski, Tashia M; Eisl, Holger M; Werbe-Fuentes, Jordan; Gorczynski, John; Goranson, Chris; Wolff, Mary S; Markowitz, Steven B

    2010-12-01

    We assessed humidity-corrected particulate matter (PM(2.5)) exposure and physical activity (using global positioning system monitors and diaries) among 18 people who commuted by car to Queens College, New York, New York, for 5 days, and then switched to commuting for the next 5 days via public transportation. The PM(2.5) differed little between car and public transportation commutes (1.41 μg/M(3)·min; P = .226). Commuting by public transportation rather than by car increased energy expenditure (+124 kcal/day; P < .001) equivalent to the loss of 1 pound of body fat per 6 weeks.

  6. IPv6 transport experiment using the GMPLS-controlled network of JGN II

    NASA Astrophysics Data System (ADS)

    Okamoto, S.; Otani, T.

    2005-11-01

    IPv6 transport over the GMPLS-controlled optical network of JGN II was experimentally investigated, and four FastEthernet IPv6 streams were successfully transported with OSPFv3 routing information exchange.

  7. Review of petroleum transport network models and their applicability to a national refinery model

    SciTech Connect

    Hooker, J. N.

    1982-04-01

    This report examines four petroleum transport network models to determine whether parts of them can be incorporated into the transportation component of a national refinery model. Two questions in particular are addressed. (a) How do the models under examination represent the oil transport network, estimate link capacities, and calculate transport costs. (b) Are any of these network representations, capacity estimates, or cost functions suitable for inclusion in a linear programming model of oil refinery and primary distribution in the US. Only pipeline and waterway transport is discussed. The models examined are the Department of Energy's OILNET model, the Department of Transportation's Freight Energy Model, the Federal Energy Administration Petroleum Transportation Network Model, and an Oak Ridge National Laboratory oil pipeline energy model. Link capacity and cost functions are recommended for each transport mode. The coefficients of the recommended pipeline cost functions remain to be estimated.

  8. Adaptive fuzzy-neural-network control for maglev transportation system.

    PubMed

    Wai, Rong-Jong; Lee, Jeng-Dao

    2008-01-01

    A magnetic-levitation (maglev) transportation system including levitation and propulsion control is a subject of considerable scientific interest because of highly nonlinear and unstable behaviors. In this paper, the dynamic model of a maglev transportation system including levitated electromagnets and a propulsive linear induction motor (LIM) based on the concepts of mechanical geometry and motion dynamics is developed first. Then, a model-based sliding-mode control (SMC) strategy is introduced. In order to alleviate chattering phenomena caused by the inappropriate selection of uncertainty bound, a simple bound estimation algorithm is embedded in the SMC strategy to form an adaptive sliding-mode control (ASMC) scheme. However, this estimation algorithm is always a positive value so that tracking errors introduced by any uncertainty will cause the estimated bound increase even to infinity with time. Therefore, it further designs an adaptive fuzzy-neural-network control (AFNNC) scheme by imitating the SMC strategy for the maglev transportation system. In the model-free AFNNC, online learning algorithms are designed to cope with the problem of chattering phenomena caused by the sign action in SMC design, and to ensure the stability of the controlled system without the requirement of auxiliary compensated controllers despite the existence of uncertainties. The outputs of the AFNNC scheme can be directly supplied to the electromagnets and LIM without complicated control transformations for relaxing strict constrains in conventional model-based control methodologies. The effectiveness of the proposed control schemes for the maglev transportation system is verified by numerical simulations, and the superiority of the AFNNC scheme is indicated in comparison with the SMC and ASMC strategies.

  9. Advanced public transportation systems deployment in the United States: Update, January 1999. Final report, July--December 1998

    SciTech Connect

    Casey, R.F.

    1999-01-01

    This report documents work performed under FTA`s Advanced Public Transportation Systems (APTS) Program, a program structured to undertake research and development of innovative applications of advanced navigation, information, and communication technologies that most benefit public transportation.

  10. Strategies to attract auto users to public transportation. Final report

    SciTech Connect

    Dueker, K.J.; Strathman, J.G.; Bianco, M.J.; Rufolo, A.; Mildner, G.C.S.

    1998-12-31

    This report will be of interest to transportation and urban planners and to local decisionmakers. The effectiveness of automobile parking strategies as a means of increasing transit ridership was analyzed. Eight strategies affecting the price and availability of parking and transit service levels were examined, alone and in combination, to assess their effects on travel mode choice, particularly transit. The final chapter of the report is an implementation guide for transportation planners and decisionmakers.

  11. Cascading failures coupled model of interdependent double layered public transit network

    NASA Astrophysics Data System (ADS)

    Zhang, Lin; Fu, Bai-Bai; Li, Shu-Bin

    2016-06-01

    Taking urban public transit network as research perspective, this work introduces the influences of adjacent stations on definition of station initial load, the connected edge transit capacity, and the coupled capacity to modify traditional load-capacity cascading failures (CFs) model. Furthermore, we consider the coupled effect of lower layered public transit network on the CFs of upper layered public transit network, and construct CFs coupled model of double layered public transit network with “interdependent relationship”. Finally, taking Jinan city’s public transit network as example, we give the dynamics simulation analysis of CFs under different control parameters based on measurement indicator of station cascading failures ratio (abbreviated as CF) and the scale of time-step cascading failures (abbreviated as TCFl), get the influencing characteristics of various control parameters, and verify the feasibility of CFs coupled model of double layered public transit network.

  12. Intelligent Urban Public Transportation for Accessibility Dedicated to People with Disabilities

    PubMed Central

    Zhou, Haiying; Hou, Kun-Mean; Zuo, Decheng; Li, Jian

    2012-01-01

    The traditional urban public transport system generally cannot provide an effective access service for people with disabilities, especially for disabled, wheelchair and blind (DWB) passengers. In this paper, based on advanced information & communication technologies (ICT) and green technologies (GT) concepts, a dedicated public urban transportation service access system named Mobi+ has been introduced, which facilitates the mobility of DWB passengers. The Mobi+ project consists of three subsystems: a wireless communication subsystem, which provides the data exchange and network connection services between buses and stations in the complex urban environments; the bus subsystem, which provides the DWB class detection & bus arrival notification services; and the station subsystem, which implements the urban environmental surveillance & bus auxiliary access services. The Mobi+ card that supports multi-microcontroller multi-transceiver adopts the fault-tolerant component-based hardware architecture, in which the dedicated embedded system software, i.e., operating system micro-kernel and wireless protocol, has been integrated. The dedicated Mobi+ embedded system provides the fault-tolerant resource awareness communication and scheduling mechanism to ensure the reliability in data exchange and service provision. At present, the Mobi+ system has been implemented on the buses and stations of line ‘2’ in the city of Clermont-Ferrand (France). The experiential results show that, on one hand the Mobi+ prototype system reaches the design expectations and provides an effective urban bus access service for people with disabilities; on the other hand the Mobi+ system is easily to deploy in the buses and at bus stations thanks to its low energy consumption and small form factor. PMID:23112622

  13. Intelligent urban public transportation for accessibility dedicated to people with disabilities.

    PubMed

    Zhou, Haiying; Hou, Kun-Mean; Zuo, Decheng; Li, Jian

    2012-01-01

    The traditional urban public transport system generally cannot provide an effective access service for people with disabilities, especially for disabled, wheelchair and blind (DWB) passengers. In this paper, based on advanced information & communication technologies (ICT) and green technologies (GT) concepts, a dedicated public urban transportation service access system named Mobi+ has been introduced, which facilitates the mobility of DWB passengers. The Mobi+ project consists of three subsystems: a wireless communication subsystem, which provides the data exchange and network connection services between buses and stations in the complex urban environments; the bus subsystem, which provides the DWB class detection & bus arrival notification services; and the station subsystem, which implements the urban environmental surveillance & bus auxiliary access services. The Mobi+ card that supports multi-microcontroller multi-transceiver adopts the fault-tolerant component-based hardware architecture, in which the dedicated embedded system software, i.e., operating system micro-kernel and wireless protocol, has been integrated. The dedicated Mobi+ embedded system provides the fault-tolerant resource awareness communication and scheduling mechanism to ensure the reliability in data exchange and service provision. At present, the Mobi+ system has been implemented on the buses and stations of line '2' in the city of Clermont-Ferrand (France). The experiential results show that, on one hand the Mobi+ prototype system reaches the design expectations and provides an effective urban bus access service for people with disabilities; on the other hand the Mobi+ system is easily to deploy in the buses and at bus stations thanks to its low energy consumption and small form factor.

  14. Noise-assisted energy transport in electrical oscillator networks with off-diagonal dynamical disorder

    PubMed Central

    León-Montiel, Roberto de J.; Quiroz-Juárez, Mario A.; Quintero-Torres, Rafael; Domínguez-Juárez, Jorge L.; Moya-Cessa, Héctor M.; Torres, Juan P.; Aragón, José L.

    2015-01-01

    Noise is generally thought as detrimental for energy transport in coupled oscillator networks. However, it has been shown that for certain coherently evolving systems, the presence of noise can enhance, somehow unexpectedly, their transport efficiency; a phenomenon called environment-assisted quantum transport (ENAQT) or dephasing-assisted transport. Here, we report on the experimental observation of such effect in a network of coupled electrical oscillators. We demonstrate that by introducing stochastic fluctuations in one of the couplings of the network, a relative enhancement in the energy transport efficiency of 22.5 ± 3.6% can be observed. PMID:26610864

  15. Noise-assisted energy transport in electrical oscillator networks with off-diagonal dynamical disorder.

    PubMed

    León-Montiel, Roberto de J; Quiroz-Juárez, Mario A; Quintero-Torres, Rafael; Domínguez-Juárez, Jorge L; Moya-Cessa, Héctor M; Torres, Juan P; Aragón, José L

    2015-11-27

    Noise is generally thought as detrimental for energy transport in coupled oscillator networks. However, it has been shown that for certain coherently evolving systems, the presence of noise can enhance, somehow unexpectedly, their transport efficiency; a phenomenon called environment-assisted quantum transport (ENAQT) or dephasing-assisted transport. Here, we report on the experimental observation of such effect in a network of coupled electrical oscillators. We demonstrate that by introducing stochastic fluctuations in one of the couplings of the network, a relative enhancement in the energy transport efficiency of 22.5 ± 3.6% can be observed.

  16. Resilient design of recharging station networks for electric transportation vehicles

    SciTech Connect

    Kris Villez; Akshya Gupta; Venkat Venkatasubramanian

    2011-08-01

    As societies shift to 'greener' means of transportation using electricity-driven vehicles one critical challenge we face is the creation of a robust and resilient infrastructure of recharging stations. A particular issue here is the optimal location of service stations. In this work, we consider the placement of battery replacing service station in a city network for which the normal traffic flow is known. For such known traffic flow, the service stations are placed such that the expected performance is maximized without changing the traffic flow. This is done for different scenarios in which roads, road junctions and service stations can fail with a given probability. To account for such failure probabilities, the previously developed facility interception model is extended. Results show that service station failures have a minimal impact on the performance following robust placement while road and road junction failures have larger impacts which are not mitigated easily by robust placement.

  17. 76 FR 11554 - Fiscal Year 2010 Public Transportation on Indian Reservations Program Project Selections

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-02

    ... Federal Transit Administration Fiscal Year 2010 Public Transportation on Indian Reservations Program Project Selections AGENCY: Federal Transit Administration, DOT. ACTION: Notice of Award. SUMMARY: The Federal Transit Administration (FTA) announces the selection of projects to be funded using Fiscal...

  18. 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: Federal Transit Administration (FTA), DOT. ACTION: Notice. SUMMARY: This notice announces final environmental actions taken by the Federal Transit Administration (FTA) for projects in the following...

  19. 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 Program AGENCY: Federal Transit Administration (FTA), DOT. ACTION: Notice of Funding Availability: Solicitation of Grant Proposals for FY 2012 Tribal Transit Program Funds. SUMMARY: The Federal...

  20. 76 FR 60963 - Notice of Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-30

    ... Federal Transit Administration Notice of Limitation on Claims Against Proposed Public Transportation Projects AGENCY: Federal Transit Administration (FTA), DOT. ACTION: Notice of limitation on claims. SUMMARY: This notice announces final environmental actions taken by the Federal Transit Administration (FTA)...

  1. 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: Federal Transit Administration (FTA), DOT. ACTION: Notice. SUMMARY: This notice announces final environmental actions taken by the Federal Transit Administration (FTA) for the Baltimore Red Line...

  2. 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: Federal Transit Administration (FTA), DOT. ACTION: Notice. SUMMARY: This notice announces final environmental actions taken by the Federal Transit Administration (FTA) for the Perris Valley Line...

  3. Getting Around. Unit I: Public Transportation. Student Lesson #4. English for Living.

    ERIC Educational Resources Information Center

    New York State Education Dept., Albany. Bureau of Bilingual Education.

    To assist the youthful learner of English as a second language in dealing with handling urban public transportation, a series of dialogs, comprehension questions, readings, and points of discussion are presented. The text is illustrated. (JB)

  4. A Case for Open Network Health Systems: Systems as Networks in Public Mental Health

    PubMed Central

    Rhodes, Michael Grant; de Vries, Marten W.

    2017-01-01

    Increases in incidents involving so-called confused persons have brought attention to the potential costs of recent changes to public mental health (PMH) services in the Netherlands. Decentralized under the (Community) Participation Act (2014), local governments must find resources to compensate for reduced central funding to such services or "innovate." But innovation, even when pressure for change is intense, is difficult. This perspective paper describes experience during and after an investigation into a particularly violent incident and murder. The aim was to provide recommendations to improve the functioning of local PMH services. The investigation concluded that no specific failure by an individual professional or service provider facility led to the murder. Instead, also as a result of the Participation Act that severed communication lines between individuals and organizations, information sharing failures were likely to have reduced system level capacity to identify risks. The methods and analytical frameworks employed to reach this conclusion, also lead to discussion as to the plausibility of an unconventional solution. If improving communication is the primary problem, non-hierarchical information, and organizational networks arise as possible and innovative system solutions. The proposal for debate is that traditional "health system" definitions, literature and narratives, and operating assumptions in public (mental) health are ‘locked in’ constraining technical and organization innovations. If we view a "health system" as an adaptive system of economic and social "networks," it becomes clear that the current orthodox solution, the so-called integrated health system, typically results in a "centralized hierarchical" or "tree" network. An overlooked alternative that breaks out of the established policy narratives is the view of a ‘health systems’ as a non-hierarchical organizational structure or ‘Open Network.’ In turn, this opens new

  5. Full Text Clustering and Relationship Network Analysis of Biomedical Publications

    PubMed Central

    Guan, Renchu; Yang, Chen; Marchese, Maurizio; Liang, Yanchun; Shi, Xiaohu

    2014-01-01

    Rapid developments in the biomedical sciences have increased the demand for automatic clustering of biomedical publications. In contrast to current approaches to text clustering, which focus exclusively on the contents of abstracts, a novel method is proposed for clustering and analysis of complete biomedical article texts. To reduce dimensionality, Cosine Coefficient is used on a sub-space of only two vectors, instead of computing the Euclidean distance within the space of all vectors. Then a strategy and algorithm is introduced for Semi-supervised Affinity Propagation (SSAP) to improve analysis efficiency, using biomedical journal names as an evaluation background. Experimental results show that by avoiding high-dimensional sparse matrix computations, SSAP outperforms conventional k-means methods and improves upon the standard Affinity Propagation algorithm. In constructing a directed relationship network and distribution matrix for the clustering results, it can be noted that overlaps in scope and interests among BioMed publications can be easily identified, providing a valuable analytical tool for editors, authors and readers. PMID:25250864

  6. Improved Results for Route Planning in Stochastic Transportation Networks

    NASA Technical Reports Server (NTRS)

    Boyan, Justin; Mitzenmacher, Michael

    2000-01-01

    In the bus network problem, the goal is to generate a plan for getting from point X to point Y within a city using buses in the smallest expected time. Because bus arrival times are not determined by a fixed schedule but instead may be random. the problem requires more than standard shortest path techniques. In recent work, Datar and Ranade provide algorithms in the case where bus arrivals are assumed to be independent and exponentially distributed. We offer solutions to two important generalizations of the problem, answering open questions posed by Datar and Ranade. First, we provide a polynomial time algorithm for a much wider class of arrival distributions, namely those with increasing failure rate. This class includes not only exponential distributions but also uniform, normal, and gamma distributions. Second, in the case where bus arrival times are independent and geometric discrete random variable,. we provide an algorithm for transportation networks of buses and trains, where trains run according to a fixed schedule.

  7. 76 FR 82031 - Commercial Space Transportation Advisory Committee; Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-29

    ... Advisory Committee Risk Management Working Group Teleconference. SUMMARY: Pursuant to Section 10(a)(2) of... teleconference of the Commercial Space Transportation Advisory Committee (COMSTAC) Risk Management Working Group. The teleconference will take place on Tuesday, January 24, 2012, starting at 1:30 p.m....

  8. 77 FR 35102 - Commercial Space Transportation Advisory Committee; Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-12

    ... Working Group (OWG) of the Commercial Space Transportation Advisory Committee (COMSTAC). The teleconference will take place on Tuesday, July 17, 2012, starting at 1 p.m. Eastern Daylight Time. Individuals... relevant written statements for the COMSTAC working group members to consider under the advisory...

  9. Manufacturing Consent for Privatization in Public Education: The Rise of a Social Finance Network in Canada

    ERIC Educational Resources Information Center

    Poole, Wendy; Sen, Vicheth; Fallon, Gerald

    2016-01-01

    Multiple forms of privatization are emerging in the Canadian public sector, including public-private partnerships. This article focuses on one approach to public-private partnerships called "social finance," and a network of public, private, and not-for-profit organizations that promotes social finance as a means of funding public…

  10. Health implications of social networks for children living in public housing.

    PubMed

    Kennedy-Hendricks, Alene; Schwartz, Heather L; Griffin, Beth Ann; Burkhauser, Susan; Green, Harold D; Kennedy, David P; Pollack, Craig Evan

    2015-11-01

    This study sought to examine whether: (1) the health composition of the social networks of children living in subsidized housing within market rate developments (among higher-income neighbors) differs from the social network composition of children living in public housing developments (among lower-income neighbors); and (2) children's social network composition is associated with children's own health. We found no significant differences in the health characteristics of the social networks of children living in these different types of public housing. However, social network composition was significantly associated with several aspects of children's own health, suggesting the potential importance of social networks for the health of vulnerable populations.

  11. 78 FR 53790 - Public Forum-Safety Culture: Enhancing Transportation Safety

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-30

    ... SAFETY BOARD Public Forum--Safety Culture: Enhancing Transportation Safety On Tuesday and Wednesday... Culture: Enhancing Transportation Safety.'' The forum will begin at 9:00 a.m. on both days and is open to... Culture; Organizational Leadership Perspectives on Safety Culture; Safety Culture Management and...

  12. 77 FR 33019 - International Standards on the Transport of Dangerous Goods; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-04

    ... persons that PHMSA will conduct a public meeting in preparation for the 41st session of the United Nations... consider proposals for the 18th Revised Edition of the United Nations Recommendations on the Transport of... agenda may be obtained from the United Nations Transport Division's Web site at...

  13. 77 FR 69927 - International Standards on the Transport of Dangerous Goods; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-21

    ... persons that PHMSA will conduct a public meeting in preparation for the 42nd session of the United Nations... 18th Revised Edition of the United Nations Recommendations on the Transport of Dangerous Goods Model... from the United Nations Transport Division's Web site at...

  14. 76 FR 78329 - Commercial Space Transportation Advisory Committee; Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-16

    ... contact Susan Lender, Designated Federal Officer (DFO), (the Contact Person listed below) by phone or... public may request a copy from Susan Lender, DFO (the Contact Person listed below). Interested members of... to submit written statements should contact Susan Lender, DFO, (the Contact Person listed below)...

  15. 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... environmental action taken by the Federal Transit Administration (FTA) for a project in New York, NY. The purpose of this notice is to announce publicly the environmental decision by FTA on the subject...

  16. Transportation Management. A Major Occupational Group in the Public Service Cluster.

    ERIC Educational Resources Information Center

    Gwinnett County Schools, GA.

    Part of a course designed to acquaint high school students with basic information concerning careers in public service, this student guide is one of nine (each with accompaning teacher's manual) which constitute a course entitled "Orientation to Public Service." Focus in the units covered by the guide is on transportation management, one…

  17. Transportation Management. A Major Occupational Group in the Public Service Cluster. Teacher's Manual.

    ERIC Educational Resources Information Center

    Gwinnett County Schools, GA.

    Part of a course designed to acquaint high school students with basic information concerning careers in public service, this teacher's manual is one of nine (each with accompanying student guide) which constitute a course entitled "Orientation to Public Service." Focus in the units covered by the manual is on transportation management,…

  18. Anomalous transport in fracture networks: field scale experiments and modelling

    NASA Astrophysics Data System (ADS)

    Kang, P. K.; Le Borgne, T.; Bour, O.; Dentz, M.; Juanes, R.

    2012-12-01

    Anomalous transport is widely observed in different settings and scales of transport through porous and fractured geologic media. A common signature of anomalous transport is the late-time power law tailing in breakthrough curves (BTCs) during tracer tests. Various conceptual models of anomalous transport have been proposed, including multirate mass transfer, continuous time random walk, and stream tube models. Since different conceptual models can produce equally good fits to a single BTC, tracer test interpretation has been plagued with ambiguity. Here, we propose to resolve such ambiguity by analyzing BTCs obtained from both convergent and push-pull flow configurations at two different fracture planes. We conducted field tracer tests in a fractured granite formation close to Ploemeur, France. We observe that BTC tailing depends on the flow configuration and the injection fracture. Specifically the tailing disappears under push-pull geometry, and when we injected at a fracture with high flux (Figure 1). This indicates that for this fractured granite, BTC tailing is controlled by heterogeneous advection and not by matrix diffusion. To explain the change in tailing behavior for different flow configurations, we employ a simple lattice network model with heterogeneous conductivity distribution. The model assigns random conductivities to the fractures and solves the Darcy equation for an incompressible fluid, enforcing mass conservation at fracture intersections. The mass conservation constraint yields a correlated random flow through the fracture system. We investigate whether BTC tailing can be explained by the spatial distribution of preferential flow paths and stagnation zones, which is controlled by the conductivity variance and correlation length. By combining the results from the field tests and numerical modeling, we show that the reversibility of spreading is a key mechanism that needs to be captured. We also demonstrate the dominant role of the injection

  19. CSI Index Of Customer's Satisfaction Applied In The Area Of Public Transport

    NASA Astrophysics Data System (ADS)

    Poliaková, Adela

    2015-06-01

    In Western countries, the new visions are applied in quality control for an integrated public transport system. Public transport puts the customer at the centre of our decision making in achieving customer satisfaction with provided service. Sustainable surveys are kept among customers. A lot of companies are collecting huge databases containing over 30,000 voices of customers, which demonstrates the current satisfaction levels across the public transport service. Customer satisfaction with a provided service is a difficult task. In this service, the quality criteria are not clearly defined, and it is therefore difficult to define customer satisfaction. The paper introduces a possibility of CSI index application in conditions of the Slovak Republic transport area.

  20. Cost & efficiency evaluation of a publicly financed & publicly delivered referral transport service model in three districts of Haryana State, India

    PubMed Central

    Prinja, Shankar; Manchanda, Neha; Aggarwal, Arun Kumar; Kaur, Manmeet; Jeet, Gursimer; Kumar, Rajesh

    2013-01-01

    Background & objectives: Various models of referral transport services have been introduced in different States in India with an aim to reduce maternal and infant mortality. Most of the research on referral transport has focussed on coverage, quality and timeliness of the service with not much information on cost and efficiency. This study was undertaken to analyze the cost of a publicly financed and managed referral transport service model in three districts of Haryana State, and to assess its cost and technical efficiency. Methods: Data on all resources spent for delivering referral transport service, during 2010, were collected from three districts of Haryana State. Costs incurred at State level were apportioned using appropriate methods. Data Envelopment Analysis (DEA) technique was used to assess the technical efficiency of ambulances. To estimate the efficient scale of operation for ambulance service, the average cost was regressed on kilometres travelled for each ambulance station using a quadratic regression equation. Results: The cost of referral transport per year varied from ₹5.2 million in Narnaul to ₹9.8 million in Ambala. Salaries (36-50%) constituted the major cost. Referral transport was found to be operating at an average efficiency level of 76.8 per cent. Operating an ambulance with a patient load of 137 per month was found to reduce unit costs from an average ₹ 15.5 per km to ₹ 9.57 per km. Interpretation & conclusions: Our results showed that the publicly delivered referral transport services in Haryana were operating at an efficient level. Increasing the demand for referral transport services among the target population represents an opportunity for further improving the efficiency of the underutilized ambulances. PMID:24521648

  1. Tuberculosis in public ground transport - is there enough evidence to justify contact tracing?

    PubMed

    Mohr, Oliver; Schink, Susanne Barbara; Eckmanns, Tim; Krause, Gérard

    2015-01-01

    Travel in public transport, especially in confined spaces, provides an opportunity for the transmission of tuberculosis (TB). In air travel, tracing of passengers to control the further spread of a pathogen is a more or less established approach in infectious disease control in many industrialized countries; however, literature reviews on the risk of TB transmission during public ground travel do not show robust evidence. On short trips, contact tracing (CT) of passengers may be unfeasible since passenger data are generally not collected. In long-distance ground travel, passenger data may not be collected routinely; incomplete data and limited or delayed access to passenger details may be further obstacles. The logistic hurdles and limited evidence suggest that CT in public ground transportation should not be a priority of TB control. However, under specific circumstances, CT in public ground transport might be considered on a case-by-case basis after an evidence-based risk assessment.

  2. Multiobjective analysis of a public wellfield using artificial neural networks

    USGS Publications Warehouse

    Coppola, E.A.; Szidarovszky, F.; Davis, D.; Spayd, S.; Poulton, M.M.; Roman, E.

    2007-01-01

    As competition for increasingly scarce ground water resources grows, many decision makers may come to rely upon rigorous multiobjective techniques to help identify appropriate and defensible policies, particularly when disparate stakeholder groups are involved. In this study, decision analysis was conducted on a public water supply wellfield to balance water supply needs with well vulnerability to contamination from a nearby ground water contaminant plume. With few alternative water sources, decision makers must balance the conflicting objectives of maximizing water supply volume from noncontaminated wells while minimizing their vulnerability to contamination from the plume. Artificial neural networks (ANNs) were developed with simulation data from a numerical ground water flow model developed for the study area. The ANN-derived state transition equations were embedded into a multiobjective optimization model, from which the Pareto frontier or trade-off curve between water supply and wellfield vulnerability was identified. Relative preference values and power factors were assigned to the three stakeholders, namely the company whose waste contaminated the aquifer, the community supplied by the wells, and the water utility company that owns and operates the wells. A compromise pumping policy that effectively balances the two conflicting objectives in accordance with the preferences of the three stakeholder groups was then identified using various distance-based methods. ?? 2006 National Ground Water Association.

  3. Multiobjective analysis of a public wellfield using artificial neural networks.

    PubMed

    Coppola, Emery A; Szidarovszky, Ferenc; Davis, Donald; Spayd, Steven; Poulton, Mary M; Roman, Eric

    2007-01-01

    As competition for increasingly scarce ground water resources grows, many decision makers may come to rely upon rigorous multiobjective techniques to help identify appropriate and defensible policies, particularly when disparate stakeholder groups are involved. In this study, decision analysis was conducted on a public water supply wellfield to balance water supply needs with well vulnerability to contamination from a nearby ground water contaminant plume. With few alternative water sources, decision makers must balance the conflicting objectives of maximizing water supply volume from noncontaminated wells while minimizing their vulnerability to contamination from the plume. Artificial neural networks (ANNs) were developed with simulation data from a numerical ground water flow model developed for the study area. The ANN-derived state transition equations were embedded into a multiobjective optimization model, from which the Pareto frontier or trade-off curve between water supply and wellfield vulnerability was identified. Relative preference values and power factors were assigned to the three stakeholders, namely the company whose waste contaminated the aquifer, the community supplied by the wells, and the water utility company that owns and operates the wells. A compromise pumping policy that effectively balances the two conflicting objectives in accordance with the preferences of the three stakeholder groups was then identified using various distance-based methods.

  4. 47 CFR 68.110 - Compatibility of the public switched telephone network and terminal equipment.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... network and terminal equipment. 68.110 Section 68.110 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES (CONTINUED) CONNECTION OF TERMINAL EQUIPMENT TO THE TELEPHONE NETWORK Conditions on Use of Terminal Equipment § 68.110 Compatibility of the public switched telephone network...

  5. 47 CFR 68.201 - Connection to the public switched telephone network.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... network. 68.201 Section 68.201 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES (CONTINUED) CONNECTION OF TERMINAL EQUIPMENT TO THE TELEPHONE NETWORK Terminal Equipment Approval Procedures § 68.201 Connection to the public switched telephone network. Terminal equipment...

  6. Instructional Applications of Virginia's Public Education Network (VA PEN): Thomas Jefferson On-Line.

    ERIC Educational Resources Information Center

    Willett-Smith, Stephanie

    The motivational value of Virginia's Public Education Network (VA PEN), specifically the Thomas Jefferson On-line discussion group, is examined in this study. The instructional value of the network with respect to student motivation in fourth grade students of varied ability was gauged through observation of actual hands-on network experience,…

  7. Lévy Walk Navigation in Complex Networks: A Distinct Relation between Optimal Transport Exponent and Network Dimension

    NASA Astrophysics Data System (ADS)

    Weng, Tongfeng; Small, Michael; Zhang, Jie; Hui, Pan

    2015-11-01

    We investigate, for the first time, navigation on networks with a Lévy walk strategy such that the step probability scales as pij ~ dij-α, where dij is the Manhattan distance between nodes i and j, and α is the transport exponent. We find that the optimal transport exponent αopt of such a diffusion process is determined by the fractal dimension df of the underlying network. Specially, we theoretically derive the relation αopt = df + 2 for synthetic networks and we demonstrate that this holds for a number of real-world networks. Interestingly, the relationship we derive is different from previous results for Kleinberg navigation without or with a cost constraint, where the optimal conditions are α = df and α = df + 1, respectively. Our results uncover another general mechanism for how network dimension can precisely govern the efficient diffusion behavior on diverse networks.

  8. In-Band Asymmetry Compensation for Accurate Time/Phase Transport over Optical Transport Network

    PubMed Central

    Siu, Sammy; Hu, Hsiu-fang; Lin, Shinn-Yan; Liao, Chia-Shu; Lai, Yi-Liang

    2014-01-01

    The demands of precise time/phase synchronization have been increasing recently due to the next generation of telecommunication synchronization. This paper studies the issues that are relevant to distributing accurate time/phase over optical transport network (OTN). Each node and link can introduce asymmetry, which affects the adequate time/phase accuracy over the networks. In order to achieve better accuracy, protocol level full timing support is used (e.g., Telecom-Boundary clock). Due to chromatic dispersion, the use of different wavelengths consequently causes fiber link delay asymmetry. The analytical result indicates that it introduces significant time error (i.e., phase offset) within 0.3397 ns/km in C-band or 0.3943 ns/km in L-band depending on the wavelength spacing. With the proposed scheme in this paper, the fiber link delay asymmetry can be compensated relying on the estimated mean fiber link delay by the Telecom-Boundary clock, while the OTN control plane is responsible for processing the fiber link delay asymmetry to determine the asymmetry compensation in the timing chain. PMID:24982948

  9. Learning Traffic as Images: A Deep Convolutional Neural Network for Large-Scale Transportation Network Speed Prediction.

    PubMed

    Ma, Xiaolei; Dai, Zhuang; He, Zhengbing; Ma, Jihui; Wang, Yong; Wang, Yunpeng

    2017-04-10

    This paper proposes a convolutional neural network (CNN)-based method that learns traffic as images and predicts large-scale, network-wide traffic speed with a high accuracy. Spatiotemporal traffic dynamics are converted to images describing the time and space relations of traffic flow via a two-dimensional time-space matrix. A CNN is applied to the image following two consecutive steps: abstract traffic feature extraction and network-wide traffic speed prediction. The effectiveness of the proposed method is evaluated by taking two real-world transportation networks, the second ring road and north-east transportation network in Beijing, as examples, and comparing the method with four prevailing algorithms, namely, ordinary least squares, k-nearest neighbors, artificial neural network, and random forest, and three deep learning architectures, namely, stacked autoencoder, recurrent neural network, and long-short-term memory network. The results show that the proposed method outperforms other algorithms by an average accuracy improvement of 42.91% within an acceptable execution time. The CNN can train the model in a reasonable time and, thus, is suitable for large-scale transportation networks.

  10. Lagrangian Flow networks: a new way to characterize transport and connectivity in geophysical flows

    NASA Astrophysics Data System (ADS)

    Ser-Giacomi, Enrico; Hernandez-Garcia, Emilio; Lopez, Cristobal; Rossi, Vincent; Vasile, Ruggero

    2015-04-01

    Water and air transport are among the basic processes shaping the climate of our planet. Heat and salinity fluxes change sea water density, and thus drive the global thermohaline circulation. Atmospheric winds force the ocean motion, and also transport moisture, heat or chemicals, impacting the regional climate. We describe transport among different regions of the ocean or the atmosphere by flow networks, giving a discrete and robust representation of the fluid advection dynamics. We use network-theory tools to gain insights into transport problem. Local and global features of the networks are extracted from many numerical experiments to give a time averaged description of the system. Classical concepts like dispersion, mixing and connectivity are finally related to a set of network-like objects contributing to build a "dictionary" between network measures and physical quantities in geophysical flows.

  11. Modeling in-situ transport of uranine and colloids in the fracture network in KURT.

    PubMed

    Kim, Jung-Woo; Lee, Jae-Kwang; Baik, Min-Hoon; Jeong, Jongtae

    2015-02-01

    An in-situ dipole migration experiment was conducted using the conservative tracer uranine and latex colloids in KAERI (Korea Atomic Energy Research Institute) Underground Research Tunnel (KURT). The location and dimensions of the fractures between the two boreholes were estimated using the results of a borehole image processing system (BIPS) investigation, and the connectivity of the fractures was evaluated by a packer test. To investigate the flow and transport of uranine and colloids through an in-situ fracture network, a fracture network transport model was newly developed. The model consists of a series of one-dimensional advection-dispersion-matrix diffusion equations for each channel of the fracture network. Using the fracture network transport model, the most probable representation and the hydrologic parameters of the fracture network can be estimated by fitting the breakthrough of uranine. While the fracture network might not be unique, the representation chosen was adequate to describe the breakthrough of uranine and it represents a reasonable approach to modeling transport in the fracture network. An additional evaluation showed that the colloid transport in this study was influenced by filtration on the fracture surface rather than the enhancement of the colloid velocity. Overall, the model can explain successfully the in-situ experimental results of uranine and colloid transports through the fracture network.

  12. 76 FR 25695 - Public Health Information Network (PHIN) Messaging Guide for Syndromic Surveillance

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-05

    ... HUMAN SERVICES Centers for Disease Control and Prevention Public Health Information Network (PHIN... submit written comments to the following address: Public Health Informatics and Technology Program Office... representative from the Public Health Informatics and Technology Program Office to schedule your visit....

  13. Evaluation of Metatags of Web Sites of the Ohio Public Library Network.

    ERIC Educational Resources Information Center

    Karpenko, Volodymyr

    This study was to conducted to define how metatags are used by Ohio public library webmasters and to determine the de facto standard for metatag usage. The 106 Ohio public library World Wide Web sites accessible through the Ohio Public Libraries Information Network (OPLIN) were evaluated using a statistical analysis of the HTLM code and content of…

  14. 47 CFR 90.18 - Public Safety 700 MHz Nationwide Broadband Network.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Public Safety 700 MHz Nationwide Broadband Network. 90.18 Section 90.18 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Public Safety Radio Pool § 90.18 Public...

  15. Commuter exposure to aromatic VOCs in public transportation modes in Hong Kong.

    PubMed

    Lau, Wai-Lun; Chan, Lo-Yin

    2003-06-01

    This study investigated commuter exposure to aromatic volatile organic compounds (VOCs) in different commuting microenvironments. In Hong Kong, more than 90% of the local citizens rely on public transport facilities in their daily commutes. During five winter months in late 2001 and early 2002, in-vehicle monitoring was performed in nine popular public transportation modes: tram, public light bus, air-conditioned bus, non-air-conditioned bus, taxi, ferry and three railway systems (Mass Transit Railway-MTR, Kowloon-Canton Railway-KCR and Light Rail Transit-LRT). These transports were grouped into three categories: railway transport, roadway transport and marine transport. Air samples of benzene, toluene, ethylbenzene and m/p/o-xylene were collected by canisters and analysed by gas chromatography and mass selective detector technique. Results indicated that the in-vehicle VOC exposure levels were greatly influenced by the mode of transport. For benzene, mean concentration ranged from 4.8 to 6.1 microg x m(-3) in roadway transports, 3.0-3.8 microg x m(-3) in railway transports and it was 2.1 microg x m(-3) in ferry. Regardless of the results in MTR and air-conditioned buses, the VOC levels in roadway transport were the highest and was followed by railway transport. The exposure levels in marine transport were the lowest. The TEX concentrations were found to be substantially higher in air-conditioned buses and MTR trains than in other transports, suggesting the existence of additional solvent-related sources in their vehicle interiors. Measurements in non-air-conditioned double deck vehicles indicate that there was slightly higher VOC levels in the lower deck than in the upper deck microenvironment. The average upper to lower deck exposure ratio ranged from 0.79 to 0.87 in trams and 0.78-0.83 in non-air-conditioned buses, depending on the compound of concern. The VOC exposure levels of public transport commuters in Hong Kong are far lower than those in most oversea

  16. 25 CFR 170.413 - What is the public role in developing the long-range transportation plan?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false What is the public role in developing the long-range... Roads Program Facilities Long-Range Transportation Planning § 170.413 What is the public role in developing the long-range transportation plan? BIA or the tribe must solicit public involvement. If there...

  17. Identifying the Critical Links in Road Transportation Networks: Centrality-based approach utilizing structural properties

    SciTech Connect

    Chinthavali, Supriya

    2016-04-01

    Surface transportation road networks share structural properties similar to other complex networks (e.g., social networks, information networks, biological networks, and so on). This research investigates the structural properties of road networks for any possible correlation with the traffic characteristics such as link flows those determined independently. Additionally, we define a criticality index for the links of the road network that identifies the relative importance in the network. We tested our hypotheses with two sample road networks. Results show that, correlation exists between the link flows and centrality measures of a link of the road (dual graph approach is followed) and the criticality index is found to be effective for one test network to identify the vulnerable nodes.

  18. Spatial spread of an epidemic through public transportation systems with a hub.

    PubMed

    Xu, Fei; Connell McCluskey, C; Cressman, Ross

    2013-11-01

    This article investigates an epidemic spreading among several locations through a transportation system, with a hub connecting these locations. Public transportation is not only a bridge through which infections travel from one location to another but also a place where infections occur since individuals are typically in close proximity to each other due to the limited space in these systems. A mathematical model is constructed to study the spread of an infectious disease through such systems. A variant of the next generation method is proposed and used to provide upper and lower bounds of the basic reproduction number for the model. Our investigation indicates that increasing transportation efficiency, and improving sanitation and ventilation of the public transportation system decrease the chance of an outbreak occurring. Moreover, discouraging unnecessary travel during an epidemic also decreases the chance of an outbreak. However, reducing travel by infectives while allowing susceptibles to travel may not be enough to avoid an outbreak.

  19. Advanced public transportation systems: State of the art update `98. Final report, July-December 1997

    SciTech Connect

    Casey, R.F.; Labell, L.N.; LoVecchio, J.A.; Ow, R.S.; Royal, J.W.

    1998-01-01

    This report is the latest in a series of State-of-the-Art reports, the last of which was published in January 1996. It contains the results of an investigation of the extent of adoption of advanced technology in the provision of public transportation service in North America. It focused on some of the most innovative or comprehensive implementations, categorized under four types of service/technologies: Fleet Management, Traveler Information, Electronic Fare Payment, and Transportation Demand Management.

  20. Self-organization leads to supraoptimal performance in public transportation systems.

    PubMed

    Gershenson, Carlos

    2011-01-01

    The performance of public transportation systems affects a large part of the population. Current theory assumes that passengers are served optimally when vehicles arrive at stations with regular intervals. In this paper, it is shown that self-organization can improve the performance of public transportation systems beyond the theoretical optimum by responding adaptively to local conditions. This is possible because of a "slower-is-faster" effect, where passengers wait more time at stations but total travel times are reduced. The proposed self-organizing method uses "antipheromones" to regulate headways, which are inspired by the stigmergy (communication via environment) of some ant colonies.

  1. DHM in human-centered product design: a case-study on public transport vehicle.

    PubMed

    Santos, V; Guimarães, C P; Franca, G A N; Cid, G L; Paranhos, A G

    2012-01-01

    The goal of this paper is to present the advantages on the use of 3D Digital Human Models (DHM) on the design of public transport vehicles. In this case, the subjects were scanned using the WBX Cyberware 3D Whole Body Scanner, with functional and daily postures according to the use of public transportation and some especial cases, such as a mother with her offspring or a business man with his valise, so the volume of the person would be taken in consideration. A data collection was created to simulate several situations of the daily use of the vehicle.

  2. Barriers to private-sector participation in public transportation. Final report

    SciTech Connect

    Thompson, T.A.

    1986-09-01

    Chapter One considers the full range of public-transportation services the private sector could provide looking at current U.S. examples. Chapter Two describes the Federal, state, and local barriers currently limiting private-sector provision of these services. Chapter Three summarizes the unique contribution of this study: an analysis of three New York counties utilizing private operators to provide varying percentages of public transportation under different institutional structures. The full case studies of the three New York counties - Onondaga (Syracuse), Suffolk (eastern Long Island), and Westchester (New York City suburb) - are presented in Appendices A-C. Appendices D and E exemplify purchase of service contracts currently in New York.

  3. A link-adding strategy for transport efficiency of complex networks

    NASA Astrophysics Data System (ADS)

    Ma, Jinlong; Han, Weizhan; Guo, Qing; Wang, Zhenyong; Zhang, Shuai

    2016-12-01

    The transport efficiency is one of the critical parameters to evaluate the performance of a network. In this paper, we propose an improved efficient (IE) strategy to enhance the network transport efficiency of complex networks by adding a fraction of links to an existing network based on the node’s local degree centrality and the shortest path length. Simulation results show that the proposed strategy can bring better traffic capacity and shorter average shortest path length than the low-degree-first (LDF) strategy under the shortest path routing protocol. It is found that the proposed strategy is beneficial to the improvement of overall traffic handling and delivering ability of the network. This study can alleviate the congestion in networks, and is helpful to design and optimize realistic networks.

  4. International fixed satellite systems in synchronous digital hierarchy transport networks

    NASA Astrophysics Data System (ADS)

    Oei, W. S.; Tamboli, S.

    1992-10-01

    This paper discusses functional and architectural aspects and suitable networks scenarios for the integration of international fixed satellite systems, such as the INTELSAT system, in and between digital networks implementing the new CCITT synchronous digital hierarchy (SDH). The paper presents SDH transmission network functional requirements, and combines them with current and anticipated future FSS operational requirements. It is shown that integration permits the use of SDH functions and features for enhanced network service provisioning by FSS in the international network fabric, and leads to new FSS system design criteria.

  5. Major trends in public health law and practice: a network national report.

    PubMed

    Hodge, James G; Barraza, Leila; Bernstein, Jennifer; Chu, Courtney; Collmer, Veda; Davis, Corey; Griest, Megan M; Hammer, Monica S; Krueger, Jill; Lowrey, Kerri McGowan; Orenstein, Daniel G

    2013-01-01

    Since its inception in September 2010, the Network for Public Health Law has responded to hundreds of public health legal technical assistance claims from around the country. Based on a review of these data, a series of major trends in public health practice and the law are analyzed, including issues concerning: the Affordable Care Act, tobacco control, emergency legal preparedness, health information privacy, food policy, vaccination, drug overdose prevention, sports injury law, public health accreditation, and maternal breastfeeding. These and other emerging themes in public health law demonstrate the essential role of law and practice in advancing the public's health.

  6. 77 FR 6624 - Notice of Limitation on Claims Against Proposed Public Transportation Projects

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-08

    ... Transportation Projects AGENCY: Federal Transit Administration (FTA), DOT. ACTION: Notice of Limitation on Claims... (FTA) for projects in the following locations: Los Angeles, CA; Grand Rapids, Wyoming, and Kentwood... announce publicly the environmental decisions by FTA on the subject projects and to activate the...

  7. 77 FR 65443 - Commercial Space Transportation Advisory Committee-Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-26

    ... Working Group of the Commercial Space Transportation Advisory Committee (COMSTAC). The teleconferences will take place on: Tuesday November 13, 2012, Tuesday December 18, 2012, and Tuesday January 15, 2013...? Interested members of the public may submit relevant written statements for the COMSTAC working group...

  8. 76 FR 78332 - Amended Notice of Limitation on Claims Against Proposed Public Transportation Project

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-16

    ... public transportation project will be barred unless the claim is filed on or before June 13, 2012. FOR... effect; regional and project-level air quality conformity; and Record of Decision, dated November 2011... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF...

  9. 78 FR 19357 - Allocation of Public Transportation Emergency Relief Funds in Response to Hurricane Sandy

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-29

    ...'s Emergency Relief Program for recovery, relief and resiliency efforts for public transportation in... the affected agencies, excluding projects to improve the resiliency of the affected systems to future... features (resiliency projects). Consistent with FTA's interim final rule, if State or locally adopted...

  10. POLLUTION PREVENTION ALTERNATIVES FOR PUBLIC WORKS CENTER (TRANSPORTATION) WASTE FLUIDS AT NAVAL STATION MAYPORT

    EPA Science Inventory

    This report summarizes the recommended pollution prevention alternatives resulting from an investigation of operations at thePublic Works Center - Transportation Division (PWC-T) at Naval Station Mayport, located near Jacksonville Beach, Florida. il sampling and by-pass filtratio...

  11. 76 FR 25774 - International Standards on the Transport of Dangerous Goods; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-05

    ... persons that PHMSA will conduct a public meeting in preparation for the 39th session of the United Nations... UNSCOE will consider proposals for the 18th Revised Edition of the United Nations Recommendations on the... obtained from the United Nations Transport Division's Web site at:...

  12. 76 FR 68829 - International Standards on the Transport of Dangerous Goods; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-07

    ... persons that PHMSA will conduct a public meeting in preparation for the 40th session of the United Nations.... The UNSCOE will consider proposals for the 18th Revised Edition of the United Nations Recommendations... agenda may be obtained from the United Nations Transport Division's Web site at:...

  13. Research on Assessment Methods for Urban Public Transport Development in China

    PubMed Central

    Zou, Linghong; Guo, Hongwei

    2014-01-01

    In recent years, with the rapid increase in urban population, the urban travel demands in Chinese cities have been increasing dramatically. As a result, developing comprehensive urban transport systems becomes an inevitable choice to meet the growing urban travel demands. In urban transport systems, public transport plays the leading role to promote sustainable urban development. This paper aims to establish an assessment index system for the development level of urban public transport consisting of a target layer, a criterion layer, and an index layer. Review on existing literature shows that methods used in evaluating urban public transport structure are dominantly qualitative. To overcome this shortcoming, fuzzy mathematics method is used for describing qualitative issues quantitatively, and AHP (analytic hierarchy process) is used to quantify expert's subjective judgment. The assessment model is established based on the fuzzy AHP. The weight of each index is determined through the AHP and the degree of membership of each index through the fuzzy assessment method to obtain the fuzzy synthetic assessment matrix. Finally, a case study is conducted to verify the rationality and practicability of the assessment system and the proposed assessment method. PMID:25530756

  14. Research on assessment methods for urban public transport development in China.

    PubMed

    Zou, Linghong; Dai, Hongna; Yao, Enjian; Jiang, Tian; Guo, Hongwei

    2014-01-01

    In recent years, with the rapid increase in urban population, the urban travel demands in Chinese cities have been increasing dramatically. As a result, developing comprehensive urban transport systems becomes an inevitable choice to meet the growing urban travel demands. In urban transport systems, public transport plays the leading role to promote sustainable urban development. This paper aims to establish an assessment index system for the development level of urban public transport consisting of a target layer, a criterion layer, and an index layer. Review on existing literature shows that methods used in evaluating urban public transport structure are dominantly qualitative. To overcome this shortcoming, fuzzy mathematics method is used for describing qualitative issues quantitatively, and AHP (analytic hierarchy process) is used to quantify expert's subjective judgment. The assessment model is established based on the fuzzy AHP. The weight of each index is determined through the AHP and the degree of membership of each index through the fuzzy assessment method to obtain the fuzzy synthetic assessment matrix. Finally, a case study is conducted to verify the rationality and practicability of the assessment system and the proposed assessment method.

  15. A Bayesian additive model for understanding public transport usage in special events.

    PubMed

    Rodrigues, Filipe; Borysov, Stanislav; Ribeiro, Bernardete; Pereira, Francisco

    2016-12-02

    Public special events, like sports games, concerts and festivals are well known to create disruptions in transportation systems, often catching the operators by surprise. Although these are usually planned well in advance, their impact is difficult to predict, even when organisers and transportation operators coordinate. The problem highly increases when several events happen concurrently. To solve these problems, costly processes, heavily reliant on manual search and personal experience, are usual practice in large cities like Singapore, London or Tokyo. This paper presents a Bayesian additive model with Gaussian process components that combines smart card records from public transport with context information about events that is continuously mined from the Web. We develop an efficient approximate inference algorithm using expectation propagation, which allows us to predict the total number of public transportation trips to the special event areas, thereby contributing to a more adaptive transportation system. Furthermore, for multiple concurrent event scenarios, the proposed algorithm is able to disaggregate gross trip counts into their most likely components related to specific events and routine behavior. Using real data from Singapore, we show that the presented model outperforms the best baseline model by up to 26% in R2 and also has explanatory power for its individual components.

  16. Describing environmental public health data: implementing a descriptive metadata standard on the environmental public health tracking network.

    PubMed

    Patridge, Jeff; Namulanda, Gonza

    2008-01-01

    The Environmental Public Health Tracking (EPHT) Network provides an opportunity to bring together diverse environmental and health effects data by integrating}?> local, state, and national databases of environmental hazards, environmental exposures, and health effects. To help users locate data on the EPHT Network, the network will utilize descriptive metadata that provide critical information as to the purpose, location, content, and source of these data. Since 2003, the Centers for Disease Control and Prevention's EPHT Metadata Subgroup has been working to initiate the creation and use of descriptive metadata. Efforts undertaken by the group include the adoption of a metadata standard, creation of an EPHT-specific metadata profile, development of an open-source metadata creation tool, and promotion of the creation of descriptive metadata by changing the perception of metadata in the public health culture.

  17. Hybrid Approach for the Public Transportation Time Dependent Orienteering Problem with Time Windows

    NASA Astrophysics Data System (ADS)

    Garcia, Ander; Arbelaitz, Olatz; Vansteenwegen, Pieter; Souffriau, Wouter; Linaza, Maria Teresa

    The Time Dependent Orienteering Problem with Time Windows (TDOPTW) consists of a set of locations with associated time windows and scores. Visiting a location allows to collect its score as a reward. Traveling time between locations varies depending on the leave time. The objective is to obtain a route that maximizes the obtained score within a limited amount of time. In this paper we target the use of public transportation in a city, where users may move on foot or by public transportation. The approach can also be applied to the logistic sector, for example to the multimodal freight transportation. We apply an hybrid approach to tackle the problem. Experimental results for the city of San Sebastian show we are able to obtain valid routes in real-time.

  18. Pore Network Modeling of Multiphase Transport in Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers

    NASA Astrophysics Data System (ADS)

    Fazeli, Mohammadreza

    In this thesis, pore network modeling was used to study how the microstructure of the polymer electrolyte membrane (PEM) fuel cell gas diffusion layer (GDL) influences multiphase transport within the composite layer. An equivalent pore network of a GDL was used to study the effects of GDL/catalyst layer condensation points and contact quality on the spatial distribution of liquid water in the GDL. Next, pore networks extracted from synchrotron-based micro-computed tomography images of compressed GDLs were employed to simulate liquid water transport in GDL materials over a range of compression pressures, and favorable GDL compression values for preferred liquid water distributions were found for two commercially available GDL materials. Finally, a technique was developed for calculating the oxygen diffusivity in carbon paper substrates with a microporous layer (MPL) coating through pore network modeling. A hybrid network was incorporated into the pore network model, and effective diffusivity predictions of MPL coated GDL materials were obtained.

  19. Blood pressure of urban school children in relation to road-traffic noise, traffic density and presence of public transport.

    PubMed

    Paunovic, Katarina; Belojevic, Goran; Jakovljevic, Branko

    2013-01-01

    The aim of the study was to investigate the relationship between noise levels, traffic density and the presence of public transport and children's blood pressure. Another aim was to assess the applicability of public transport as a proxy indicator of noise exposure. A cross-sectional study involved 1113 children aged 7-11 years from a central municipality in Belgrade. Equivalent noise levels were measured in front of all schools and in the middle of all streets. Traffic density was defined as number of light and heavy vehicles per hour. The number of public transport vehicles was calculated from official timetables. Children's addresses were matched with noise levels and transport maps. A physician measured blood pressure with the sphygmomanometer. Children attending schools with public transport running nearby had by 1.3 mmHg higher systolic pressure than did children from schools without public transport. This relationship was independent from children's age, gender, and body mass index, family history of hypertension, some dwelling characteristics, and lifestyle habits. The association between diastolic pressure and public transport was statistically insignificant. The study indicated a possible positive association between the presence of public transport in the vicinity of schools with systolic blood pressure in 7-11 year-old schoolchildren. The presence of public transport may serve as an auxiliary indicator of noise exposure in undeveloped countries with limited capacities for noise measurement or modeling.

  20. Diverging Narratives: Evaluating the Uses of the Ideal-Typical Sequence of Transport Network Development

    ERIC Educational Resources Information Center

    Weber, Joe

    2004-01-01

    The development of new transport systems has been an important and highly visible component of economic development and spatial reorganization in the past two centuries. The Ideal-Typical Sequence of network development has been a widely used model of transport development. This paper shows that this model has been used in several different ways,…

  1. Research on urban public traffic network with multi-weights based on single bus transfer junction

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    Regarding single bus transfer junction as a research object, this paper constructs the urban traffic network models with multi-weights taking different bus lines in bus transfer junction as the network nodes, that is, the urban traffic network with multi-weights is given different properties weights at every edge. According to the method of network split, the complex network with multi-weights is split into several different single weighted complex networks. Then, we study the global synchronization of the new network model by changing congestion degrees, transfers coefficient and passenger flow density between different bus lines. Finally, analytical and simulated results are given to show the impact of different properties weights to the public traffic network balance.

  2. Health implications of social networks for children living in public housing

    PubMed Central

    Kennedy-Hendricks, Alene; Schwartz, Heather L.; Griffin, Beth Ann; Burkhauser, Susan; Green, Harold D.; Kennedy, David P.; Pollack, Craig Evan

    2015-01-01

    This study sought to examine whether: (1) the health composition of the social networks of children living in subsidized housing within market rate developments (among higher-income neighbors) differs from the social network composition of children living in public housing developments (among lower-income neighbors); and (2) children’s social network composition is associated with children’s own health. We found no significant differences in the health characteristics of the social networks of children living in these different types of public housing. However, social network composition was significantly associated with several aspects of children’s own health, suggesting the potential importance of social networks for the health of vulnerable populations. PMID:26598958

  3. Environmental Response Laboratory Network (ERLN) Public Labs Fact Sheet

    EPA Pesticide Factsheets

    Outlines goals for participation in the Environmental Response Laboratory Network, and FAQs. They play an integral role in a coordinated and operational system of labs capable of efficiently and effectively responding to incidents.

  4. Application of Fiber-Optical Techniques in the Access Transmission and Backbone Transport of Mobile Networks

    NASA Astrophysics Data System (ADS)

    Hilt, Attila; Pozsonyi, László

    2012-09-01

    Fixed access networks widely employ fiber-optical techniques due to the extremely wide bandwidth offered to subscribers. In the last decade, there has also been an enormous increase of user data visible in mobile systems. The importance of fiber-optical techniques within the fixed transmission/transport networks of mobile systems is therefore inevitably increasing. This article summarizes a few reasons and gives examples why and how fiber-optic techniques are employed efficiently in second-generation networks.

  5. Using Public Network Infrastructures for UAV Remote Sensing in Civilian Security Operations

    DTIC Science & Technology

    2011-03-01

    Using Public Network Infrastructures for UAV Remote Sensing in Civilian Security Operations Kai Daniel and Christian Wietfeld ABSTRACT Unmanned...sensing, reconnaissance, surveillance, and communication purposes. Police departments, fire brigades, and other homeland security organizations...Detection with an Autonomous Micro UAV Mesh Network. In the near future police departments, fire brigades and other homeland security

  6. Interfacing VoIP to the Public Switch Telephone Network (PSTN)

    NASA Astrophysics Data System (ADS)

    Pilgrim, Jim

    2001-07-01

    Interfacing VoIP into the current Public Switched Telephone Network is for the most part done through the use of a gateway. This gateway whether H.323, Session Initiation Protocol or Media Gateway Control Protocol is required for access into a traditional switched telephony network.

  7. Public Safety Networks--Examining Mimetic, Complexity, and Legacy Effects on Interorganizational Collaborations

    ERIC Educational Resources Information Center

    Dias, Martin A.

    2012-01-01

    The purpose of this dissertation is to examine information systems-enabled interorganizational collaborations called public safety networks--their proliferation, information systems architecture, and technology evolution. These networks face immense pressures from member organizations, external stakeholders, and environmental contingencies. This…

  8. Simulation and analysis of solute transport in 2D fracture/pipe networks: the SOLFRAC program.

    PubMed

    Bodin, Jacques; Porel, Gilles; Delay, Fred; Ubertosi, Fabrice; Bernard, Stéphane; de Dreuzy, Jean-Raynald

    2007-01-05

    The Time Domain Random Walk (TDRW) method has been recently developed by Delay and Bodin [Delay, F. and Bodin, J., 2001. Time domain random walk method to simulate transport by advection-dispersion and matrix diffusion in fracture networks. Geophys. Res. Lett., 28(21): 4051-4054.] and Bodin et al. [Bodin, J., Porel, G. and Delay, F., 2003c. Simulation of solute transport in discrete fracture networks using the time domain random walk method. Earth Planet. Sci. Lett., 6566: 1-8.] for simulating solute transport in discrete fracture networks. It is assumed that the fracture network can reasonably be represented by a network of interconnected one-dimensional pipes (i.e. flow channels). Processes accounted for are: (1) advection and hydrodynamic dispersion in the channels, (2) matrix diffusion, (3) diffusion into stagnant zones within the fracture planes, (4) sorption reactions onto the fracture walls and in the matrix, (5) linear decay, and (6) mass sharing at fracture intersections. The TDRW method is handy and very efficient in terms of computation costs since it allows for the one-step calculation of the particle residence time in each bond of the network. This method has been programmed in C++, and efforts have been made to develop an efficient and user-friendly software, called SOLFRAC. This program is freely downloadable at the URL (labo.univ-poitiers.fr/hydrasa/intranet/telechargement.htm). It calculates solute transport into 2D pipe networks, while considering different types of injections and different concepts of local dispersion within each flow channel. Post-simulation analyses are also available, such as the mean velocity or the macroscopic dispersion at the scale of the entire network. The program may be used to evaluate how a given transport mechanism influences the macroscopic transport behaviour of fracture networks. It may also be used, as is the case, e.g., with analytical solutions, to interpret laboratory or field tracer test experiments performed

  9. Safety and Security Technologies of Importance to Transportation-Disadvantaged Populations Using Public Transit

    SciTech Connect

    Truett, Lorena Faith; Boundy, Robert Gary

    2006-01-01

    All travelers have concerns about safety and security. For transportation-disadvantaged persons (i.e., older adults, persons with disabilities, and low-income individuals), these concerns are amplified by the vulnerability of the individuals. Safety and security can be improved for transportation-disadvantaged populations through the use of technology. Specific technologies include vehicle tracking systems, silent alarm systems, security cameras, and way-finding navigation systems. Other innovative safety devices and programs provide additional safety and security. Five sites across the United States were visited to determine how agencies of different sizes using different approaches meet the needs of these special populations. The agencies noted that technologies of benefit to the transportation-disadvantaged communities generally benefit all users of public transportation.

  10. Public Libraries and the Internet, 2002: Internet Connectivity and Networked Services.

    ERIC Educational Resources Information Center

    Bertot, John Carlo; McClure, Charles R.

    This study updated statistics about public library outlet and system Internet connectivity and network services using the 1997 public library dataset produced by the National Center for Education Statistics through the Federal-State Cooperative System. Using geographic information system-based techniques, a research team at the Florida State…

  11. 76 FR 17657 - Medical Device Epidemiology Network 2011: Second Annual Public Workshop

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-30

    ... HUMAN SERVICES Food and Drug Administration Medical Device Epidemiology Network 2011: Second Annual... and Drug Administration (FDA) is announcing a public workshop entitled ``Medical Device Epidemiology... for studying medical device performance. Date and Time: The public workshop will be held on April...

  12. Opportunistic Hybrid Transport Protocol (OHTP) for Cognitive Radio Ad Hoc Sensor Networks.

    PubMed

    Bin Zikria, Yousaf; Nosheen, Summera; Ishmanov, Farruh; Kim, Sung Won

    2015-12-15

    The inefficient assignment of spectrum for different communications purposes, plus technology enhancements and ever-increasing usage of wireless technology is causing spectrum scarcity. To address this issue, one of the proposed solutions in the literature is to access the spectrum dynamically or opportunistically. Therefore, the concept of cognitive radio appeared, which opens up a new research paradigm. There is extensive research on the physical, medium access control and network layers. The impact of the transport layer on the performance of cognitive radio ad hoc sensor networks is still unknown/unexplored. The Internet's de facto transport protocol is not well suited to wireless networks because of its congestion control mechanism. We propose an opportunistic hybrid transport protocol for cognitive radio ad hoc sensor networks. We developed a new congestion control mechanism to differentiate true congestion from interruption loss. After such detection and differentiation, we propose methods to handle them opportunistically. There are several benefits to window- and rate-based protocols. To exploit the benefits of both in order to enhance overall system performance, we propose a hybrid transport protocol. We empirically calculate the optimal threshold value to switch between window- and rate-based mechanisms. We then compare our proposed transport protocol to Transmission Control Protocol (TCP)-friendly rate control, TCP-friendly rate control for cognitive radio, and TCP-friendly window-based control. We ran an extensive set of simulations in Network Simulator 2. The results indicate that the proposed transport protocol performs better than all the others.

  13. Extreme weather impacts on European networks of transport

    NASA Astrophysics Data System (ADS)

    Leviakangas, P.

    2012-04-01

    The EWENT project addresses the European Union (EU) policies and strategies related to climate change, with a particular focus on extreme weather impacts on the EU transportation system. This project is funded by the Seventh Framework Programme (Transports, call ID FPT7-TPT-2008-RTD-1). EWENT Work Package 1 (WP1) focuses particularly on identification and definition of extreme weather events within the European transport system. In the context of the EWENT project, the following definition for extreme weather events related to transport systems was used: "Extreme events are generally rare events. The events cause the exceeding of maximum values and/or pre-existing (measured) high (low) thresholds of certain weather parameters and generate impacts that are harmful to any part of the transport system (infrastructures, operations, vehicles, passengers or cargo)". Weather has major impacts on transportation. EWENT WP1 used three different approaches to assess the impacts and consequences extreme weather phenomena cause to the transport system. Firstly, an extensive traditional review of the professional literature has been carried out. Secondly, media mining has been done in order to obtain more empirical data and assess which transport modes in different parts of Europe seem to be most affected. Thirdly, a compilation of specific case studies on past extreme incidents has been prepared, helping to assess the specific consequences of certain phenomena. EWENT WP1 introduces a review of extreme weather phenomena and identifies their impacts and consequences on European transport system. All modes of transport are covered. Critical threshold values for most relevant weather phenomena that affect different transport modes have been established. The related impacts and consequences result in deterioration in the service level of transportation system. A dozen different impact mechanisms have been charted. The collaborators in the team for this part of the EWENT Project are

  14. [Public, decentralized and community health networks in Bolivia].

    PubMed

    Lavadenz, F; Schwab, N; Straatman, H

    2001-03-01

    Health sector reform in Bolivia is based primarily on the principles of decentralization and equity, and with the objectives of improving quality and of expanding health services coverage in rural and low-income areas of the country. As an experiment in reform, the Bolivian Ministry of Health and Social Welfare, the department of La Paz, and the municipality of El Alto signed an agreement with a nongovernmental organization (NGO), transferring to the NGO the overall management of one of the health services networks in El Alto. The transfer was based on a management contract that had process and outcome indicators for the network. A year after implementation began, the preliminary results suggest that through the agreement the quality of management and services has improved, health services coverage has expanded, and the network's primary care services have been strengthened. Bed occupancy rates are generally very low in secondary hospitals in Bolivia, with that figure being just 43% in the department of La Paz in 1999. However, in the second 6 months of operation of the El Alto network the occupancy rate for the network's hospital reached 84%. Between the first 6 months of 1999 and the same period in 2000, outpatient consultations increased by 55% in the network (83% in the hospital and 18% in the network's primary care centers). Over that same period, institutional deliveries increased by 41% and the percentage of deliveries in the primary care centers grew from 5% of the total to 9%. A recent user survey found that 87% of the people receiving care in the network felt highly satisfied with the service they had received, and 75% of the persons surveyed said they would recommend the service to others. These are not typical data for health services in Bolivia. This pilot effort suggests that a change in the organization and management of a health services network, with a separation of the roles of purchaser and provider, combined with management based on results and

  15. Strategies for Transporting Data Between Classified and Unclassified Networks

    DTIC Science & Technology

    2016-03-01

    datagram protocol (UDP) must be used. The UDP is typically used when speed is a higher priority than data integrity, such as in music or video streaming...allows communications from low-level unclassified networks up to high-level secret classified networks. Created at the Communications- Electronics ...and enables web-based queries to electronically transfer information (ref. 3). The high- speed guard component validates security, ISR information

  16. Weak and strong publics: drawing on Nancy Fraser to explore parental participation in neonatal networks

    PubMed Central

    Gibson, Andrew J.; Lewando‐Hundt, Gillian; Blaxter, Loraine

    2014-01-01

    Abstract Aims  We draw on the work of Nancy Fraser, and in particular her concepts of weak and strong publics, to analyze the process of parental involvement in managed neonatal network boards. Background  Public involvement has moved beyond the individual level to include greater involvement of both patients and the public in governance. However, there is relatively little literature that explores the nature and outcomes of long‐term patient involvement initiatives or has attempted to theorize, particularly at the level of corporate decision making, the process of patient and public involvement. Methods  A repeated survey of all neonatal network managers in England was carried out in 2006–07 to capture developments and changes in parental representation over this time period. This elicited information about the current status of parent representation on neonatal network boards. Four networks were also selected as case studies. This involved interviews with key members of each network board, interviews with parent representatives, observation of meetings and access to board minutes. Results  Data collected show that a wide range of approaches to involving parents has been adopted. These range from decisions not to involve parents at this level to relatively well‐developed systems designed to link parent representatives on network boards to parents in neonatal units. Conclusion  Despite these variations, we suggest that parental participation within neonatal services remains an example of a weak public because the parent representatives had limited participation with little influence on decision making. PMID:22040481

  17. Network as transconcept: elements for a conceptual demarcation in the field of public health

    PubMed Central

    Amaral, Carlos Eduardo Menezes; Bosi, Maria Lúcia Magalhães

    2016-01-01

    ABSTRACT The main proposal to set up an articulated mode of operation of health services has been the concept of network, which has been appropriated in different ways in the field of public health, as it is used in other disciplinary fields or even taking it from common sense. Amid the diversity of uses and concepts, we recognize the need for rigorous conceptual demarcation about networks in the field of health. Such concern aims to preserve the strategic potential of this concept in the research and planning in the field, overcoming uncertainties and distortions still observed in its discourse-analytic circulation in public health. To this end, we will introduce the current uses of network in different disciplinary fields, emphasizing dialogues with the field of public health. With this, we intend to stimulate discussions about the development of empirical dimensions and analytical models that may allow us to understand the processes produced within and around health networks. PMID:27556965

  18. Japanese development and testing of the network establishment practices scale for community and public health nurses.

    PubMed

    Koshida, Mihoko; Morita, Takae

    2013-03-01

    The practices required by community and public health nurses to establish community networks mainly involve communicative competencies. Assessment through development and testing of such competencies is necessary for community and public health nurse educators and practitioners around the world to create and maintain a mutual support network. The purpose of this study was to develop and test a scale for community and public health nurse practices to establish and maintain community networks, and to then determine construct validity in a factorial structure model. The participants were 3970 community and public health nurses in Japan. A 43-item list was developed from a literature review, individual interviews, and repeated examinations. The secondary structural model consisted of four factors with 21 items. The internal consistency of the 21 items was highly reliable (Cronbach's α = 0.915). Confirmatory factor analysis by structural equation modeling showed the fit criteria to be statistically significant. Attributes of the community and public health nurses (age, years of experience, work municipalities, work positions, and educational institutions) showed significant relationships with the scale scores. The findings validated the efficacy of the Network Establishment Practices Scale to assess community and public health nurse practices to establish community networks.

  19. Networking for large-scale science: infrastructure, provisioning, transport and application mapping

    NASA Astrophysics Data System (ADS)

    Rao, Nageswara S.; Carter, Steven M.; Wu, Qishi; Wing, William R.; Zhu, Mengxia; Mezzacappa, Anthony; Veeraraghavan, Malathi; Blondin, John M.

    2005-01-01

    Large-scale science computations and experiments require unprecedented network capabilities in the form of large bandwidth and dynamically stable connections to support data transfers, interactive visualizations, and monitoring and steering operations. A number of component technologies dealing with the infrastructure, provisioning, transport and application mappings must be developed and/or optimized to achieve these capabilities. We present a brief account of the following technologies that contribute toward achieving these network capabilities: (a) DOE UltraScienceNet and NSF CHEETAH network testbeds that provide on-demand and scheduled dedicated network connections; (b) experimental results on transport protocols that achieve close to 100% utilization on dedicated 1Gbps wide-area channels; (c) a scheme for optimally mapping a visualization pipeline onto a network to minimize the end-to-end delays; and (d) interconnect configuration and protocols that provides multiple Gbps flows from Cray X1 to external hosts.

  20. Fractional quantum mechanics on networks: Long-range dynamics and quantum transport.

    PubMed

    Riascos, A P; Mateos, José L

    2015-11-01

    In this paper we study the quantum transport on networks with a temporal evolution governed by the fractional Schrödinger equation. We generalize the dynamics based on continuous-time quantum walks, with transitions to nearest neighbors on the network, to the fractional case that allows long-range displacements. By using the fractional Laplacian matrix of a network, we establish a formalism that combines a long-range dynamics with the quantum superposition of states; this general approach applies to any type of connected undirected networks, including regular, random, and complex networks, and can be implemented from the spectral properties of the Laplacian matrix. We study the fractional dynamics and its capacity to explore the network by means of the transition probability, the average probability of return, and global quantities that characterize the efficiency of this quantum process. As a particular case, we explore analytically these quantities for circulant networks such as rings, interacting cycles, and complete graphs.

  1. Fractional quantum mechanics on networks: Long-range dynamics and quantum transport

    NASA Astrophysics Data System (ADS)

    Riascos, A. P.; Mateos, José L.

    2015-11-01

    In this paper we study the quantum transport on networks with a temporal evolution governed by the fractional Schrödinger equation. We generalize the dynamics based on continuous-time quantum walks, with transitions to nearest neighbors on the network, to the fractional case that allows long-range displacements. By using the fractional Laplacian matrix of a network, we establish a formalism that combines a long-range dynamics with the quantum superposition of states; this general approach applies to any type of connected undirected networks, including regular, random, and complex networks, and can be implemented from the spectral properties of the Laplacian matrix. We study the fractional dynamics and its capacity to explore the network by means of the transition probability, the average probability of return, and global quantities that characterize the efficiency of this quantum process. As a particular case, we explore analytically these quantities for circulant networks such as rings, interacting cycles, and complete graphs.

  2. Findings from an organizational network analysis to support local public health management.

    PubMed

    Merrill, Jacqueline; Caldwell, Michael; Rockoff, Maxine L; Gebbie, Kristine; Carley, Kathleen M; Bakken, Suzanne

    2008-07-01

    We assessed the feasibility of using organizational network analysis in a local public health organization. The research setting was an urban/suburban county health department with 156 employees. The goal of the research was to study communication and information flow in the department and to assess the technique for public health management. Network data were derived from survey questionnaires. Computational analysis was performed with the Organizational Risk Analyzer. Analysis revealed centralized communication, limited interdependencies, potential knowledge loss through retirement, and possible informational silos. The findings suggested opportunities for more cross program coordination but also suggested the presences of potentially efficient communication paths and potentially beneficial social connectedness. Managers found the findings useful to support decision making. Public health organizations must be effective in an increasingly complex environment. Network analysis can help build public health capacity for complex system management.

  3. Impact of pore size variability and network coupling on electrokinetic transport in porous media

    NASA Astrophysics Data System (ADS)

    Alizadeh, Shima; Bazant, Martin Z.; Mani, Ali

    2016-11-01

    We have developed and validated an efficient and robust computational model to study the coupled fluid and ion transport through electrokinetic porous media, which are exposed to external gradients of pressure, electric potential, and concentration. In our approach a porous media is modeled as a network of many pores through which the transport is described by the coupled Poisson-Nernst-Planck-Stokes equations. When the pore sizes are random, the interactions between various modes of transport may provoke complexities such as concentration polarization shocks and internal flow circulations. These phenomena impact mixing and transport in various systems including deionization and filtration systems, supercapacitors, and lab-on-a-chip devices. In this work, we present simulations of massive networks of pores and we demonstrate the impact of pore size variation, and pore-pore coupling on the overall electrokinetic transport in porous media.

  4. Electronic networks, community intermediaries, and the public's health.

    PubMed Central

    Milio, N

    1996-01-01

    Information technology (IT) has the potential to assist disadvantaged communities in gaining access to mainstream resources, and to a new kind of community health-supporting infrastructure. Federal and state information technology policy will affect how and how well community institutions can reach their goals, collaborate with service agencies, and effectively advocate investing essential, health-supporting resources in their communities. The current information technology focus of the health professions is institution and provider-oriented. It should have a wider scope to include community-based organizations. Laborious efforts undertaken by community-based organizations (CBOs) with only a patchwork of resources and without policy support suggest their value to the public's health. Increasingly burdened public health organizations should examine the public health interest in closing the gap between IT-poor and IT-rich organizations and develop a strategy for building inclusive electronic webs with CBOs. PMID:8826628

  5. SWNT nano-engineered networks strongly increase charge transport in P3HT.

    PubMed

    Boulanger, Nicolas; Yu, Junchun; Barbero, David R

    2014-10-21

    We demonstrate the formation of arrays of 3D nanosized networks of interconnected single-wall carbon nanotubes (SWNTs) with well defined dimensions in a poly-3-hexylthiophene (P3HT) thin film. These novel nanotube nano-networks produce efficient ohmic charge transport, even at very low nanotube loadings and low voltages. An increase in conductivity between one and two orders of magnitude is observed compared to a random network. The formation of these nano-engineered networks is compatible with large area imprinting and roll to roll processes, which makes it highly desirable for opto-electronic and energy conversion applications using carbon nanotubes.

  6. Travel Behavior Change in Older Travelers: Understanding Critical Reactions to Incidents Encountered in Public Transport.

    PubMed

    Sundling, Catherine

    2015-11-18

    Accessibility of travel may be better understood if psychological factors underlying change in travel behavior are known. This paper examines older (65+) travelers' motives for changing their travel behavior. These changes are grounded in critical incidents earlier encountered in public-transport travel. A scientific framework is developed based on cognitive and behavioral theory. In 29 individual interviews, travelers' critical reactions (i.e., cognitive, emotional, and/or behavioral) to 77 critical incidents were examined. By applying critical incident technique (CIT), five reaction themes were identified that had generated travel-behavior change: firm restrictions, unpredictability, unfair treatment, complicated trips, and earlier adverse experiences. To improve older travelers' access to public transport, key findings were: (a) service must be designed so as to strengthen the feeling of being in control throughout the journey; (b) extended personal service would increase predictability in the travel chain and decrease travel complexity; consequently,

  7. Benefits assessment of Advanced Public Transportation Systems (APTS). Final report, October 1995-July 1996

    SciTech Connect

    Goeddel, D.

    1996-07-30

    This report documents work performed under FTA`s Advanced Public Transportation Systems (APTS) Program, a program structured to undertake research and development of innovative applications of advanced navigation, information, and communication technologies that most benefit public transportation. This report presents the results of an analysis conducted by the Volpe Center, for the FTA, to provide an `order-of-magnitude` estimate of the expected benefits to the transit industry with the application of APTS technologies. Specifically, the study identified and quantified the major benefits derived from current applications of APTS technologies within the transit industry and projected current APTS benefits to a national level based on forecasts and reasonable assumptions on the potential future applications of such technologies within the transit industry.

  8. Advanced public transportation systems deployment in the United States. Final report, July 1995-January 1996

    SciTech Connect

    Casey, R.F.; Labell, L.N.

    1996-08-01

    This report documents work performed under FTA`s Advanced Public Transportation Systems (APTS) Program, a program structured to undertake research and development of innovative applications of advanced navigation, information, and communication technologies that most benefit public transportation. This report is a compilation of existing and planned deployments of APTS technologies and services. The information was collected during the Fall of 1995 and was obtained through contacts with one or more persons at each agency. The objective was to include information from all agencies who submitted information for the 1993 National Transit Database (NTD) Report Year, the last year for which NTD data was available at the time. A total of 464 agencies provided information for this study. Those with no existing or planned APTS systems are not included herein.

  9. Price of anarchy in transportation networks: efficiency and optimality control.

    PubMed

    Youn, Hyejin; Gastner, Michael T; Jeong, Hawoong

    2008-09-19

    Uncoordinated individuals in human society pursuing their personally optimal strategies do not always achieve the social optimum, the most beneficial state to the society as a whole. Instead, strategies form Nash equilibria which are often socially suboptimal. Society, therefore, has to pay a price of anarchy for the lack of coordination among its members. Here we assess this price of anarchy by analyzing the travel times in road networks of several major cities. Our simulation shows that uncoordinated drivers possibly waste a considerable amount of their travel time. Counterintuitively, simply blocking certain streets can partially improve the traffic conditions. We analyze various complex networks and discuss the possibility of similar paradoxes in physics.

  10. Smooth information flow in temperature climate network reflects mass transport

    NASA Astrophysics Data System (ADS)

    Hlinka, Jaroslav; Jajcay, Nikola; Hartman, David; Paluš, Milan

    2017-03-01

    A directed climate network is constructed by Granger causality analysis of air temperature time series from a regular grid covering the whole Earth. Using winner-takes-all network thresholding approach, a structure of a smooth information flow is revealed, hidden to previous studies. The relevance of this observation is confirmed by comparison with the air mass transfer defined by the wind field. Their close relation illustrates that although the information transferred due to the causal influence is not a physical quantity, the information transfer is tied to the transfer of mass and energy.

  11. Network and the Fragmentation of the Public Sphere.

    ERIC Educational Resources Information Center

    Sassi, Sinikka

    1996-01-01

    Focuses on two main communication technology themes: debate on the contemporary cultural turn predicted by new technologies; and implications of that disputed turn for some core concepts of the public sphere. Presents a series of elemental analyses regarding whether the Internet strengthens the political model of representation and lobbyism rather…

  12. Way-Finding Support in Public Transport Environments provided by the NAMO Mobile Travel Assistance System.

    PubMed

    Bühler, Christian; Heck, Helmut; Nietzio, Annika; Reins, Frank; Berker, Frank

    2015-01-01

    The NAMO travel assistance system is a mobile application providing support for elder travellers in public transport and on foot. The system combines technical and human support during the journey, especially in situations where many seniors experience orientation difficulties. Several approaches to way-finding and orientation support have been developed. This paper introduces the different approaches and presents the results of the extensive user evaluations, leading to recommendations for future development of mobile travel assistance applications for seniors.

  13. Cooperation among cancer cells as public goods games on Voronoi networks.

    PubMed

    Archetti, Marco

    2016-05-07

    Cancer cells produce growth factors that diffuse and sustain tumour proliferation, a form of cooperation that can be studied using mathematical models of public goods in the framework of evolutionary game theory. Cell populations, however, form heterogeneous networks that cannot be described by regular lattices or scale-free networks, the types of graphs generally used in the study of cooperation. To describe the dynamics of growth factor production in populations of cancer cells, I study public goods games on Voronoi networks, using a range of non-linear benefits that account for the known properties of growth factors, and different types of diffusion gradients. The results are surprisingly similar to those obtained on regular graphs and different from results on scale-free networks, revealing that network heterogeneity per se does not promote cooperation when public goods diffuse beyond one-step neighbours. The exact shape of the diffusion gradient is not crucial, however, whereas the type of non-linear benefit is an essential determinant of the dynamics. Public goods games on Voronoi networks can shed light on intra-tumour heterogeneity, the evolution of resistance to therapies that target growth factors, and new types of cell therapy.

  14. An Appraisal of Social Network Theory and Analysis as Applied to Public Health: Challenges and Opportunities.

    PubMed

    Valente, Thomas W; Pitts, Stephanie R

    2016-12-15

    The use of social network theory and analysis methods as applied to public health has expanded greatly in the past decade, yielding a significant academic literature that spans almost every conceivable health issue. This review identifies several important theoretical challenges that confront the field but also provides opportunities for new research. These challenges include (a) measuring network influences, (b) identifying appropriate influence mechanisms, (c) the impact of social media and computerized communications, (d) the role of networks in evaluating public health interventions, and (e) ethics. Next steps for the field are outlined and the need for funding is emphasized. Recently developed network analysis techniques, technological innovations in communication, and changes in theoretical perspectives to include a focus on social and environmental behavioral influences have created opportunities for new theory and ever broader application of social networks to public health topics. Expected final online publication date for the Annual Review of Public Health Volume 38 is March 20, 2017. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

  15. Potential of public transit as a transportation control measure: Case studies

    SciTech Connect

    Sillings, M.

    1998-07-01

    This report is the final product of the Clean Air Project of the National Association of Regional Councils/NARC. It documents a nationwide study of transit projects and programs initiated in the wake of the 1990 Clean Air Act Amendments/CAAA and the Intermodal Surface Transportation Efficiency Act of 1991/ISTEA. The study purpose was to assess the experience, limitations, and value of public transit as a potential transportation control measure/TCM, i.e., generates significant air quality benefits by eliminating or reducing emissions from motor vehicles. Four in-depth case studies and six additional projects featured as innovations in transportation are offered as examples investigating the potential of transit as a TCM. These case studies and innovations highlight the efforts of ten metropolitan areas and transit agencies which have succeed in developing and implementing innovative transit strategies.

  16. Quality of service in optical packet switched DWDM transport networks

    NASA Astrophysics Data System (ADS)

    Bjornstad, Steinar; Stol, Norvald; Hjelme, Dag R.

    2002-09-01

    For support of multimedia applications in Internet, at least four service classes are normally outlined. We expect optical packet switching to be of special interest in terabit capacity networks with a high number of wavelengths. Our analysis shows that when the wavelength dimension is used for contention resolution, and number of wavelengths is 32 or higher, node-delay is negligible. However buffering in optical packet switches is a scarce resource which use should be minimized. Based on the requirement of the future network, and on our packet switch performance analysis, we suggest reducing the number of service classes to two: A normal class (NCT) with medium low packet loss and a low need for buffering, and a high class (HCT) with a minimum of packet loss. Performance of a buffer reservation scheme is analyzed by simulation. Assuming the network of today with 10 % HCT traffic, assigning four buffer inputs to the HCT traffic, a difference in optical packet loss ratio of three orders of magnitude can be obtained. The same difference in optical packet loss ratio can be obtained if 50 % HCT traffic is assumed (network of tomorrow), by assigning a higher number of buffer inputs.

  17. Property Valuation and Radioactive Materials Transportation: A Legal, Economic and Public Perception Analysis

    SciTech Connect

    Holm, J. A.; Thrower, A. W.; Widmayer, D. A.; Portner, W.

    2003-02-26

    The shipment of transuranic (TRU) radioactive waste to the Waste Isolation Pilot Plant (WIPP) in New Mexico raised a serious socioeconomic issue - the potential devaluation of property values due to the transportation of TRU waste from generator sites to the disposal facility. In 1992, the New Mexico Supreme Court held in City of Santa Fe v. Komis that a loss in value from public perception of risk was compensable. This issue has become an extremely important one for the development of the Yucca Mountain repository in Nevada for disposal of spent nuclear fuel and high-level radioactive waste. Much research has been conducted about the potential impacts of transportation of spent fuel and radioactive waste. This paper examines the pertinent studies conducted since the Komis case. It examines how the public debate on radioactive materials transportation continues and is now focused on transportation of high-level waste and spent nuclear fuel to the proposed Yucca Mountain repository. Finally, the paper suggests a path forward DOE can take to address this issue.

  18. Relations between macropore network characteristics and the degree of preferential solute transport

    NASA Astrophysics Data System (ADS)

    Larsbo, M.; Koestel, J.; Jarvis, N.

    2014-12-01

    The characteristics of the soil macropore network determine the potential for fast transport of agrochemicals and contaminants through the soil. The objective of this study was to examine the relationships between macropore network characteristics, hydraulic properties and state variables and measures of preferential transport. Experiments were carried out under near-saturated conditions on undisturbed columns sampled from four agricultural topsoils of contrasting texture and structure. Macropore network characteristics were computed from 3-D X-ray tomography images of the soil pore system. Non-reactive solute transport experiments were carried out at five steady-state water flow rates from 2 to 12 mm h-1. The degree of preferential transport was evaluated by the normalised 5% solute arrival time and the apparent dispersivity calculated from the resulting breakthrough curves. Near-saturated hydraulic conductivities were measured on the same samples using a tension disc infiltrometer placed on top of the columns. Results showed that many of the macropore network characteristics were inter-correlated. For example, large macroporosities were associated with larger specific macropore surface areas and better local connectivity of the macropore network. Generally, an increased flow rate resulted in earlier solute breakthrough and a shifting of the arrival of peak concentration towards smaller drained volumes. Columns with smaller macroporosities, poorer local connectivity of the macropore network and smaller near-saturated hydraulic conductivities exhibited a greater degree of preferential transport. This can be explained by the fact that, with only two exceptions, global (i.e. sample scale) continuity of the macropore network was still preserved at low macroporosities. Thus, for any given flow rate, pores of larger diameter were actively conducting solute in soils of smaller near-saturated hydraulic conductivity. This was associated with larger local transport

  19. Reciprocity in spatial evolutionary public goods game on double-layered network

    PubMed Central

    Kim, Jinho; Yook, Soon-Hyung; Kim, Yup

    2016-01-01

    Spatial evolutionary games have mainly been studied on a single, isolated network. However, in real world systems, many interaction topologies are not isolated but many different types of networks are inter-connected to each other. In this study, we investigate the spatial evolutionary public goods game (SEPGG) on double-layered random networks (DRN). Based on the mean-field type arguments and numerical simulations, we find that SEPGG on DRN shows very rich interesting phenomena, especially, depending on the size of each layer, intra-connectivity, and inter-connected couplings, the network reciprocity of SEPGG on DRN can be drastically enhanced through the inter-connected coupling. Furthermore, SEPGG on DRN can provide a more general framework which includes the evolutionary dynamics on multiplex networks and inter-connected networks at the same time. PMID:27503801

  20. Oscillations, complex spatiotemporal behavior, and information transport in networks of excitatory and inhibitory neurons

    SciTech Connect

    Destexhe, A. )

    1994-08-01

    Various types of spatiotemporal behavior are described for two-dimensional networks of excitatory and inhibitory neurons with time delayed interactions. It is described how the network behaves as several structural parameters are varied, such as the number of neurons, the connectivity, and the values of synaptic weights. A transition from spatially uniform oscillations to spatiotemporal chaos via intermittentlike behavior is observed. The properties of spatiotemporally chaotic solutions are investigated by evaluating the largest positive Lyapunov exponent and the loss of correlation with distance. Finally, properties of information transport are evaluated during uniform oscillations and spatiotemporal chaos. It is shown that the diffusion coefficient increases significantly in the spatiotemporal phase similar to the increase of transport coefficients at the onset of fluid turbulence. It is proposed that such a property should be seen in other media, such as chemical turbulence or networks of oscillators. The possibility of measuring information transport from appropriate experiments is also discussed.

  1. Quantitative Evaluation of an Air-monitoring Network Using Atmospheric Transport Modeling and Frequency of Detection Methods.

    PubMed

    Rood, Arthur S; Sondrup, A Jeffrey; Ritter, Paul D

    2016-04-01

    A methodology has been developed to quantify the performance of an air-monitoring network in terms of frequency of detection. Frequency of detection is defined as the fraction of "events" that result in a detection at either a single sampler or network of samplers. An "event" is defined as a release to the atmosphere of a specified amount of activity over a finite duration that begins on a given day and hour of the year. The methodology uses an atmospheric transport model to predict air concentrations of radionuclides at the samplers for a given release time and duration. Another metric of interest determined by the methodology is called the network intensity, which is defined as the fraction of samplers in the network that have a positive detection for a given event. The frequency of detection methodology allows for evaluation of short-term releases that include effects of short-term variability in meteorological conditions. The methodology was tested using the U.S. Department of Energy Idaho National Laboratory Site ambient air-monitoring network consisting of 37 low-volume air samplers in 31 different locations covering a 17,630 km region. Releases from six major facilities distributed over an area of 1,435 km were modeled and included three stack sources and eight ground-level sources. A Lagrangian Puff air dispersion model (CALPUFF) was used to model atmospheric transport. The model was validated using historical Sb releases and measurements. Relevant 1-wk release quantities from each emission source were calculated based on a dose of 1.9×10 mSv at a public receptor (0.01 mSv assuming release persists over a year). Important radionuclides were Am, Cs, Pu, Pu, Sr, and tritium. Results show the detection frequency was over 97.5% for the entire network considering all sources and radionuclides. Network intensity results ranged from 3.75% to 62.7%. Evaluation of individual samplers indicated some samplers were poorly located and added little to the overall

  2. A turbulent transport network model in MULTIFLUX coupled with TOUGH2

    SciTech Connect

    Danko, G.; Bahrami, D.; Birkholzer, J.T.

    2011-02-15

    A new numerical method is described for the fully iterated, conjugate solution of two discrete submodels, involving (a) a transport network model for heat, moisture, and airflows in a high-permeability, air-filled cavity; and (b) a variably saturated fractured porous medium. The transport network submodel is an integrated-parameter, computational fluid dynamics solver, describing the thermal-hydrologic transport processes in the flow channel system of the cavity with laminar or turbulent flow and convective heat and mass transport, using MULTIFLUX. The porous medium submodel, using TOUGH2, is a solver for the heat and mass transport in the fractured rock mass. The new model solution extends the application fields of TOUGH2 by integrating it with turbulent flow and transport in a discrete flow network system. We present demonstrational results for a nuclear waste repository application at Yucca Mountain with the most realistic model assumptions and input parameters including the geometrical layout of the nuclear spent fuel and waste with variable heat load for the individual containers. The MULTIFLUX and TOUGH2 model elements are fully iterated, applying a programmed reprocessing of the Numerical Transport Code Functionalization model-element in an automated Outside Balance Iteration loop. The natural, convective airflow field and the heat and mass transport in a representative emplacement drift during postclosure are explicitly solved in the new model. The results demonstrate that the direction and magnitude of the air circulation patterns and all transport modes are strongly affected by the heat and moisture transport processes in the surrounding rock, justifying the need for a coupled, fully iterated model solution such as the one presented in the paper.

  3. Extending natural hazard impacts: an assessment of landslide disruptions on a national road transportation network

    NASA Astrophysics Data System (ADS)

    Postance, Benjamin; Hillier, John; Dijkstra, Tom; Dixon, Neil

    2017-01-01

    Disruptions to transportation networks by natural hazard events cause direct losses (e.g. by physical damage) and indirect socio-economic losses via travel delays and decreased transportation efficiency. The severity and spatial distribution of these losses varies according to user travel demands and which links, nodes or infrastructure assets are physically disrupted. Increasing transport network resilience, for example by targeted mitigation strategies, requires the identification of the critical network segments which if disrupted would incur undesirable or unacceptable socio-economic impacts. Here, these impacts are assessed on a national road transportation network by coupling hazard data with a transport network model. This process is illustrated using a case study of landslide hazards on the road network of Scotland. A set of possible landslide-prone road segments is generated using landslide susceptibility data. The results indicate that at least 152 road segments are susceptible to landslides, which could cause indirect economic losses exceeding £35 k for each day of closure. In addition, previous estimates for historic landslide events might be significant underestimates. For example, the estimated losses for the 2007 A83 ‘Rest and Be Thankful’ landslide are £80 k day-1, totalling £1.2 million over a 15 day closure, and are ˜60% greater than previous estimates. The spatial distribution of impact to road users is communicated in terms of ‘extended hazard impact footprints’. These footprints reveal previously unknown exposed communities and unanticipated spatial patterns of severe disruption. Beyond cost-benefit analyses for landslide mitigation efforts, the approach implemented is applicable to other natural hazards (e.g. flooding), combinations of hazards, or even other network disruption events.

  4. Harmony search optimization algorithm for a novel transportation problem in a consolidation network

    NASA Astrophysics Data System (ADS)

    Davod Hosseini, Seyed; Akbarpour Shirazi, Mohsen; Taghi Fatemi Ghomi, Seyed Mohammad

    2014-11-01

    This article presents a new harmony search optimization algorithm to solve a novel integer programming model developed for a consolidation network. In this network, a set of vehicles is used to transport goods from suppliers to their corresponding customers via two transportation systems: direct shipment and milk run logistics. The objective of this problem is to minimize the total shipping cost in the network, so it tries to reduce the number of required vehicles using an efficient vehicle routing strategy in the solution approach. Solving several numerical examples confirms that the proposed solution approach based on the harmony search algorithm performs much better than CPLEX in reducing both the shipping cost in the network and computational time requirement, especially for realistic size problem instances.

  5. Simulation of unsteady flow and solute transport in a tidal river network

    USGS Publications Warehouse

    Zhan, X.

    2003-01-01

    A mathematical model and numerical method for water flow and solute transport in a tidal river network is presented. The tidal river network is defined as a system of open channels of rivers with junctions and cross sections. As an example, the Pearl River in China is represented by a network of 104 channels, 62 nodes, and a total of 330 cross sections with 11 boundary section for one of the applications. The simulations are performed with a supercomputer for seven scenarios of water flow and/or solute transport in the Pearl River, China, with different hydrological and weather conditions. Comparisons with available data are shown. The intention of this study is to summarize previous works and to provide a useful tool for water environmental management in a tidal river network, particularly for the Pearl River, China.

  6. Observation of Noise-Assisted Transport in an All-Optical Cavity-Based Network

    NASA Astrophysics Data System (ADS)

    Viciani, Silvia; Lima, Manuela; Bellini, Marco; Caruso, Filippo

    2015-08-01

    Recent theoretical and experimental efforts have shown the remarkable and counterintuitive role of noise in enhancing the transport efficiency of complex systems. Here, we realize simple, scalable, and controllable optical fiber cavity networks that allow us to analyze the performance of transport networks for different conditions of interference, dephasing, and disorder. In particular, we experimentally demonstrate that the transport efficiency reaches a maximum when varying the external dephasing noise, i.e., a bell-like shape behavior that had been predicted only theoretically. These optical platforms are very promising simulators of quantum transport phenomena and could be used, in particular, to design and test optimal topologies of artificial light-harvesting structures for future solar energy technologies.

  7. Argentine ants (Linepithema humile) use adaptable transportation networks to track changes in resource quality.

    PubMed

    Latty, Tanya; Holmes, Michael J; Makinson, James C; Beekman, Madeleine

    2017-02-15

    Transportation networks play a crucial role in human and animal societies. For a transportation network to be efficient, it must have adequate capacity to meet traffic demand. Network design becomes increasingly difficult in situations where traffic demand can change unexpectedly. In humans, network design is often constrained by path dependency because it is difficult to move a road once it is built. A similar issue theoretically faces pheromone-trail-laying social insects; once a trail has been laid, positive feedback makes re-routing difficult because new trails cannot compete with continually reinforced pre-existing trails. In the present study, we examined the response of Argentine ant colonies and their trail networks to variable environments where resources differ in quality and change unexpectedly. We found that Argentine ant colonies effectively tracked changes in food quality such that colonies allocated the highest proportion of foragers to the most rewarding feeder. Ant colonies maximised access to high concentration feeders by building additional trails and routes connecting the nest to the feeder. Trail networks appeared to form via a pruning process in which lower traffic trails were gradually removed from the network. At the same time, we observed several instances where new trails appear to have been built to accommodate a surge in demand. The combination of trail building when traffic demand is high and trail pruning when traffic demand is low results in a demand-driven network formation system that allows ants to monopolise multiple dynamic resources.

  8. SensorNet 3 Requirements Document: Container Transportation Security Network

    DTIC Science & Technology

    2011-01-24

    operate at temperatures between - 20C and +70C. Containers are shipped to cold climates such as Alaska, United States and hot climates such as Dubai ...current and forecast weather conditions and handling time the shipper will estimate the drop-off time of the container. R-2.1.1.1.6 The TDE shall...drop-off time of the container based on current estimated pick-up time. Using estimated pickup time, forecast weather , transportation time and

  9. Review of pore network modelling of porous media: Experimental characterisations, network constructions and applications to reactive transport

    NASA Astrophysics Data System (ADS)

    Xiong, Qingrong; Baychev, Todor G.; Jivkov, Andrey P.

    2016-09-01

    Pore network models have been applied widely for simulating a variety of different physical and chemical processes, including phase exchange, non-Newtonian displacement, non-Darcy flow, reactive transport and thermodynamically consistent oil layers. The realism of such modelling, i.e. the credibility of their predictions, depends to a large extent on the quality of the correspondence between the pore space of a given medium and the pore network constructed as its representation. The main experimental techniques for pore space characterisation, including direct imaging, mercury intrusion porosimetry and gas adsorption, are firstly summarised. A review of the main pore network construction techniques is then presented. Particular focus is given on how such constructions are adapted to the data from experimentally characterised pore systems. Current applications of pore network models are considered, with special emphasis on the effects of adsorption, dissolution and precipitation, as well as biomass growth, on transport coefficients. Pore network models are found to be a valuable tool for understanding and predicting meso-scale phenomena, linking single pore processes, where other techniques are more accurate, and the homogenised continuum porous media, used by engineering community.

  10. Bidirectional 16-QAM OFDM in-building network over SMF and free-space VLC transport.

    PubMed

    Chen, Chia-Yi; Wu, Po-Yi; Lu, Hai-Han; Lin, Ying-Pyng; Wen, Jian-Ying; Hu, Fu-Chih

    2013-07-01

    A bidirectional 16-quadrature amplitude modulation (QAM) orthogonal frequency-division multiplexing (OFDM) in-building network over 20 km single-mode fiber (SMF) and 15 m free-space visible light communication (VLC) transport is proposed and experimentally demonstrated. Good bit error rate performances and clear constellation maps are obtained for 16-QAM OFDM applications in our proposed in-building networks.

  11. Analysis of the Transportation Network for the Export of US Steam Coal.

    DTIC Science & Technology

    1984-09-01

    coal demand leveled off and then dropped . Some claimed that if the price of US coal could be lowered through cheaper, more efficient transportation...market. Since 1981 there has been a weakening in the demand for coal on the world market as the price of oil dropped , and as some of the traditional...share to those maintenance costs. The vessel links are the most numerous of the transportation network, and they reflect the fact that the open water

  12. GENERAL: Mean-field Theory for Some Bus Transport Networks with Random Overlapping Clique Structure

    NASA Astrophysics Data System (ADS)

    Yang, Xu-Hua; Sun, Bao; Wang, Bo; Sun, You-Xian

    2010-04-01

    Transport networks, such as railway networks and airport networks, are a kind of random network with complex topology. Recently, more and more scholars paid attention to various kinds of transport networks and try to explore their inherent characteristics. Here we study the exponential properties of a recently introduced Bus Transport Networks (BTNs) evolution model with random overlapping clique structure, which gives a possible explanation for the observed exponential distribution of the connectivities of some BTNs of three major cities in China. Applying mean-field theory, we analyze the BTNs model and prove that this model has the character of exponential distribution of the connectivities, and develop a method to predict the growth dynamics of the individual vertices, and use this to calculate analytically the connectivity distribution and the exponents. By comparing mean-field based theoretic results with the statistical data of real BTNs, we observe that, as a whole, both of their data show similar character of exponential distribution of the connectivities, and their exponents have same order of magnitude, which show the availability of the analytical result of this paper.

  13. Large-Scale Transportation Network Congestion Evolution Prediction Using Deep Learning Theory

    PubMed Central

    Ma, Xiaolei; Yu, Haiyang; Wang, Yunpeng; Wang, Yinhai

    2015-01-01

    Understanding how congestion at one location can cause ripples throughout large-scale transportation network is vital for transportation researchers and practitioners to pinpoint traffic bottlenecks for congestion mitigation. Traditional studies rely on either mathematical equations or simulation techniques to model traffic congestion dynamics. However, most of the approaches have limitations, largely due to unrealistic assumptions and cumbersome parameter calibration process. With the development of Intelligent Transportation Systems (ITS) and Internet of Things (IoT), transportation data become more and more ubiquitous. This triggers a series of data-driven research to investigate transportation phenomena. Among them, deep learning theory is considered one of the most promising techniques to tackle tremendous high-dimensional data. This study attempts to extend deep learning theory into large-scale transportation network analysis. A deep Restricted Boltzmann Machine and Recurrent Neural Network architecture is utilized to model and predict traffic congestion evolution based on Global Positioning System (GPS) data from taxi. A numerical study in Ningbo, China is conducted to validate the effectiveness and efficiency of the proposed method. Results show that the prediction accuracy can achieve as high as 88% within less than 6 minutes when the model is implemented in a Graphic Processing Unit (GPU)-based parallel computing environment. The predicted congestion evolution patterns can be visualized temporally and spatially through a map-based platform to identify the vulnerable links for proactive congestion mitigation. PMID:25780910

  14. Large-scale transportation network congestion evolution prediction using deep learning theory.

    PubMed

    Ma, Xiaolei; Yu, Haiyang; Wang, Yunpeng; Wang, Yinhai

    2015-01-01

    Understanding how congestion at one location can cause ripples throughout large-scale transportation network is vital for transportation researchers and practitioners to pinpoint traffic bottlenecks for congestion mitigation. Traditional studies rely on either mathematical equations or simulation techniques to model traffic congestion dynamics. However, most of the approaches have limitations, largely due to unrealistic assumptions and cumbersome parameter calibration process. With the development of Intelligent Transportation Systems (ITS) and Internet of Things (IoT), transportation data become more and more ubiquitous. This triggers a series of data-driven research to investigate transportation phenomena. Among them, deep learning theory is considered one of the most promising techniques to tackle tremendous high-dimensional data. This study attempts to extend deep learning theory into large-scale transportation network analysis. A deep Restricted Boltzmann Machine and Recurrent Neural Network architecture is utilized to model and predict traffic congestion evolution based on Global Positioning System (GPS) data from taxi. A numerical study in Ningbo, China is conducted to validate the effectiveness and efficiency of the proposed method. Results show that the prediction accuracy can achieve as high as 88% within less than 6 minutes when the model is implemented in a Graphic Processing Unit (GPU)-based parallel computing environment. The predicted congestion evolution patterns can be visualized temporally and spatially through a map-based platform to identify the vulnerable links for proactive congestion mitigation.

  15. Modeling the Role of Public Transportation in Sustaining Tuberculosis Transmission in South Africa

    PubMed Central

    Andrews, Jason R.; Morrow, Carl; Wood, Robin

    2013-01-01

    Current tuberculosis notification rates in South Africa are among the highest ever recorded. Although the human immunodeficiency virus epidemic has been a critical factor, the density of respiratory contacts in high-risk environments may be an important and underappreciated driver. Using a modified Wells-Riley model for airborne disease transmission, we estimated the risk of tuberculosis transmission on 3 modes of public transit (minibus taxis, buses, and trains) in Cape Town, South Africa, using exhaled carbon dioxide as a natural tracer gas to evaluate air exchange. Carbon dioxide measurements were performed between October and December of 2011. Environmental risk, reflected in the rebreathed fraction of air, was highest in minibus taxis and lowest in trains; however, the average number of passengers sharing an indoor space was highest in trains and lowest in minibus taxis. Among daily commuters, the annual risk of tuberculosis infection was projected to be 3.5%–5.0% and was highest among minibus taxi commuters. Assuming a duration of infectiousness of 1 year, the basic reproductive number attributable to transportation was more than 1 in all 3 modes of transportation. Given its poor ventilation and high respiratory contact rates, public transportation may play a critical role in sustaining tuberculosis transmission in South African cities. PMID:23423215

  16. Modeling the role of public transportation in sustaining tuberculosis transmission in South Africa.

    PubMed

    Andrews, Jason R; Morrow, Carl; Wood, Robin

    2013-03-15

    Current tuberculosis notification rates in South Africa are among the highest ever recorded. Although the human immunodeficiency virus epidemic has been a critical factor, the density of respiratory contacts in high-risk environments may be an important and underappreciated driver. Using a modified Wells-Riley model for airborne disease transmission, we estimated the risk of tuberculosis transmission on 3 modes of public transit (minibus taxis, buses, and trains) in Cape Town, South Africa, using exhaled carbon dioxide as a natural tracer gas to evaluate air exchange. Carbon dioxide measurements were performed between October and December of 2011. Environmental risk, reflected in the rebreathed fraction of air, was highest in minibus taxis and lowest in trains; however, the average number of passengers sharing an indoor space was highest in trains and lowest in minibus taxis. Among daily commuters, the annual risk of tuberculosis infection was projected to be 3.5%-5.0% and was highest among minibus taxi commuters. Assuming a duration of infectiousness of 1 year, the basic reproductive number attributable to transportation was more than 1 in all 3 modes of transportation. Given its poor ventilation and high respiratory contact rates, public transportation may play a critical role in sustaining tuberculosis transmission in South African cities.

  17. Effects of decision-making on the transport costs across complex networks

    NASA Astrophysics Data System (ADS)

    Gourley, Sean; Johnson, Neil F.

    2005-12-01

    We analyse the effects of agents' decisions on the creation of and reaction to, congestion on a centralised network with a ring-and-hub topology. We take a fixed network model and numerically determine the global transport costs across the network as a function of capacity. These results show that as the capacity of the hub is reduced the system dynamics are driven by an interplay between stable states and critical points. The stable states are studied in detail allowing us to derive an analytic expression for the probability of crowding within the central hub. The analytic solution is in excellent agreement with the numeric results.

  18. Electrical Treeing Induced Vascular Networks for Fluid Transport

    NASA Astrophysics Data System (ADS)

    Behler, Kristopher; Wetzel, Eric

    2010-03-01

    Electrical treeing (ET) is a stepwise dielectric breakdown process in which partial discharges in a dielectric material generate a branched hollow network of tubules between the electrode and the ground. Overtime, exposure of dielectric materials to global electric fields which are lower than the dielectric strength results in electrical trees (ETs). This dielectric breakdown is exploited to induce a controlled growth of ETs in epoxies to demonstrate a fabrication technique of synthetic vascular systems in engineering materials. Both AC, ±20 kV at 100 Hz sine wave, and DC, up to -60 kV, voltages were used to grow ET in planar and volumetric systems. AC treeing induces a more bush-like highly branched structure, whereas DC treeing results in a more tree-like structure possessing mostly low ordered branches. In addition to voltage, the geometric arrangement of the electrode and ground, and the use of electrode surface treatments with multi-walled carbon nanotubes (MWCNTs) were investigated. Applications for vascular networks were demonstrated by filling the ETs with dyed liquids.

  19. [Selected work-related health problems in drivers of public transport vehicles].

    PubMed

    Siedlecka, Jadwiga

    2006-01-01

    The literature data and our own studies show that in drivers of public transport vehicles, largely intensified work-related risk factors for arterial hypertension, ischemic heart disease, duodenal and gastric ulcer diseases and back pain syndrome are found. These involves occupational risk factors as well as classic ones, such as obesity, limited physical activity or tobacco smoking. Among occupational risk factors, stress induced by the responsibility for assuring public safety in heavy urban traffic, time pressure and contacts with passengers predominate. Other burdens observed in this occupational group include specific, partly forced, position of the body at work and the shift work system. Exposure to chemical agents present in exhaust gas may increase the incidence of cancer at some sites in this group of drivers. Multifaceted burdens occurring in this occupation may impair health, leading to temporary or permanent disability to work. Therefore, there is an urgent need to develop specific preventive programs addressed to this occupational group not only because of economic reasons, but mostly to increase public transport safety.

  20. Networking expertise: Discursive coalitions and collaborative networks of experts in a public creationism controversy in the UK

    PubMed Central

    Allgaier, Joachim

    2012-01-01

    Experts do play a particular role in public socio-scientific debates, even more so if they form heterogeneous coalition with other actors and experts. A case study about a public science education controversy surrounding the teaching of evolution/creationism in the UK press is used to investigate in detail how connections and coalitions between experts and other actors involved in the controversy emerged and played out. The research focuses on the question of what role collaborative and other networks of experts played in terms of influence, visibility, credibility, consensus and weight of argument. Issues that are considered in the research are the status of the members of the coalitions forming during the debate and how it is displayed in media representations and letters and petitions, and also how these networks and coalitions of experts perform in relation to each other. PMID:23045882

  1. Networking expertise: discursive coalitions and collaborative networks of experts in a public creationism controversy in the UK.

    PubMed

    Allgaier, Joachim

    2012-04-01

    Experts do play a particular role in public socio-scientific debates, even more so if they form heterogeneous coalition with other actors and experts. A case study about a public science education controversy surrounding the teaching of evolution/creationism in the UK press is used to investigate in detail how connections and coalitions between experts and other actors involved in the controversy emerged and played out. The research focuses on the question of what role collaborative and other networks of experts played in terms of influence, visibility, credibility, consensus and weight of argument. Issues that are considered in the research are the status of the members of the coalitions forming during the debate and how it is displayed in media representations and letters and petitions, and also how these networks and coalitions of experts perform in relation to each other.

  2. Transportation Network with Fluctuating Input/Output Designed by the Bio-Inspired Physarum Algorithm

    PubMed Central

    Watanabe, Shin; Takamatsu, Atsuko

    2014-01-01

    In this paper, we propose designing transportation network topology and traffic distribution under fluctuating conditions using a bio-inspired algorithm. The algorithm is inspired by the adaptive behavior observed in an amoeba-like organism, plasmodial slime mold, more formally known as plasmodium of Physarum plycephalum. This organism forms a transportation network to distribute its protoplasm, the fluidic contents of its cell, throughout its large cell body. In this process, the diameter of the transportation tubes adapts to the flux of the protoplasm. The Physarum algorithm, which mimics this adaptive behavior, has been widely applied to complex problems, such as maze solving and designing the topology of railroad grids, under static conditions. However, in most situations, environmental conditions fluctuate; for example, in power grids, the consumption of electric power shows daily, weekly, and annual periodicity depending on the lifestyles or the business needs of the individual consumers. This paper studies the design of network topology and traffic distribution with oscillatory input and output traffic flows. The network topology proposed by the Physarum algorithm is controlled by a parameter of the adaptation process of the tubes. We observe various rich topologies such as complete mesh, partial mesh, Y-shaped, and V-shaped networks depending on this adaptation parameter and evaluate them on the basis of three performance functions: loss, cost, and vulnerability. Our results indicate that consideration of the oscillatory conditions and the phase-lags in the multiple outputs of the network is important: The building and/or maintenance cost of the network can be reduced by introducing the oscillating condition, and when the phase-lag among the outputs is large, the transportation loss can also be reduced. We use stability analysis to reveal how the system exhibits various topologies depending on the parameter. PMID:24586616

  3. Transportation network with fluctuating input/output designed by the bio-inspired Physarum algorithm.

    PubMed

    Watanabe, Shin; Takamatsu, Atsuko

    2014-01-01

    In this paper, we propose designing transportation network topology and traffic distribution under fluctuating conditions using a bio-inspired algorithm. The algorithm is inspired by the adaptive behavior observed in an amoeba-like organism, plasmodial slime mold, more formally known as plasmodium of Physarum plycephalum. This organism forms a transportation network to distribute its protoplasm, the fluidic contents of its cell, throughout its large cell body. In this process, the diameter of the transportation tubes adapts to the flux of the protoplasm. The Physarum algorithm, which mimics this adaptive behavior, has been widely applied to complex problems, such as maze solving and designing the topology of railroad grids, under static conditions. However, in most situations, environmental conditions fluctuate; for example, in power grids, the consumption of electric power shows daily, weekly, and annual periodicity depending on the lifestyles or the business needs of the individual consumers. This paper studies the design of network topology and traffic distribution with oscillatory input and output traffic flows. The network topology proposed by the Physarum algorithm is controlled by a parameter of the adaptation process of the tubes. We observe various rich topologies such as complete mesh, partial mesh, Y-shaped, and V-shaped networks depending on this adaptation parameter and evaluate them on the basis of three performance functions: loss, cost, and vulnerability. Our results indicate that consideration of the oscillatory conditions and the phase-lags in the multiple outputs of the network is important: The building and/or maintenance cost of the network can be reduced by introducing the oscillating condition, and when the phase-lag among the outputs is large, the transportation loss can also be reduced. We use stability analysis to reveal how the system exhibits various topologies depending on the parameter.

  4. Modelling temporal networks of human face-to-face contacts with public activity and individual reachability

    NASA Astrophysics Data System (ADS)

    Zhang, Yi-Qing; Cui, Jing; Zhang, Shu-Min; Zhang, Qi; Li, Xiang

    2016-02-01

    Modelling temporal networks of human face-to-face contacts is vital both for understanding the spread of airborne pathogens and word-of-mouth spreading of information. Although many efforts have been devoted to model these temporal networks, there are still two important social features, public activity and individual reachability, have been ignored in these models. Here we present a simple model that captures these two features and other typical properties of empirical face-to-face contact networks. The model describes agents which are characterized by an attractiveness to slow down the motion of nearby people, have event-triggered active probability and perform an activity-dependent biased random walk in a square box with periodic boundary. The model quantitatively reproduces two empirical temporal networks of human face-to-face contacts which are testified by their network properties and the epidemic spread dynamics on them.

  5. Multicomponent Transport through Realistic Zeolite Membranes: Characterization & Transport in Nanoporous Networks

    SciTech Connect

    William C. Conner

    2007-08-02

    These research studies focused on the characterization and transport for porous solids which comprise both microporosity and mesoporosity. Such materials represent membranes made from zeolites as well as for many new nanoporous solids. Several analytical sorption techniques were developed and evaluated by which these multi-dimensional porous solids could be quantitatively characterized. Notably an approach by which intact membranes could be studied was developed and applied to plate-like and tubular supported zeolitic membranes. Transport processes were studied experimentally and theoretically based on the characterization studies.

  6. Publications of the Jet Propulsion Laboratory, January through December 1974. [deep space network, Apollo project, information theory, and space exploration

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Formalized technical reporting is described and indexed, which resulted from scientific and engineering work performed, or managed, by the Jet Propulsion Laboratory. The five classes of publications included are technical reports, technical memorandums, articles from the bimonthly Deep Space Network Progress Report, special publications, and articles published in the open literature. The publications are indexed by author, subject, and publication type and number.

  7. Rules of the road: A qualitative and quantitative synthesis of large wood transport through drainage networks

    NASA Astrophysics Data System (ADS)

    Kramer, Natalie; Wohl, Ellen

    2017-02-01

    To effectively manage wood in rivers, we need a better understanding of wood mobility within river networks. Here, we review primarily field-based (and some numerical) studies of wood transport. We distinguish small, medium, large, and great rivers based on wood piece dimensions relative to channel and flow dimensions and dominant controls on wood transport. We suggest further identification and designation of wood transport regimes as a useful way to characterize spatial-temporal network heterogeneity and to conceptualize the primary controls on wood mobility in diverse river segments. We draw analogies between wood and bedload transport, including distinguishing Eulerian and Lagrangian approaches, exploring transport capacity, and quantifying thresholds of wood mobility. We identify mobility envelopes for remobilization of wood with relation to increasing peak discharges, stream size, and dimensionless log lengths. Wood transport in natural channels exhibits high spatial and temporal variability, with discontinuities along the channel network at bankfull flow and when log lengths equal channel widths. Although median mobilization rates increase with increasing channel size, maximum mobilization rates are greatest in medium-sized channels. Most wood is transported during relatively infrequent high flows, but flows under bankfull can transport up to 30% of stored wood. We use conceptual models of dynamic equilibrium of wood in storage and of spiralling wood transport paths through drainage networks, as well as a metaphor of traffic on a road, to explore discontinuous wood movement through a river network. The primary limitations to describing wood transport are inappropriate time scales of observation and lack of sufficient data on mobility from diverse rivers. Improving models of wood flux requires better characterization of average step lengths within the lifetime travel path of a piece of wood. We suggest that future studies focus on: (i) continuous or high

  8. Anion channels/transporters in plants: from molecular bases to regulatory networks.

    PubMed

    Barbier-Brygoo, Hélène; De Angeli, Alexis; Filleur, Sophie; Frachisse, Jean-Marie; Gambale, Franco; Thomine, Sébastien; Wege, Stefanie

    2011-01-01

    Anion channels/transporters are key to a wide spectrum of physiological functions in plants, such as osmoregulation, cell signaling, plant nutrition and compartmentalization of metabolites, and metal tolerance. The recent identification of gene families encoding some of these transport systems opened the way for gene expression studies, structure-function analyses of the corresponding proteins, and functional genomics approaches toward further understanding of their integrated roles in planta. This review, based on a few selected examples, illustrates that the members of a given gene family exhibit a diversity of substrate specificity, regulation, and intracellular localization, and are involved in a wide range of physiological functions. It also shows that post-translational modifications of transport proteins play a key role in the regulation of anion transport activity. Key questions arising from the increasing complexity of networks controlling anion transport in plant cells (the existence of redundancy, cross talk, and coordination between various pathways and compartments) are also addressed.

  9. COMPARISON OF HEPATIC PROFILE IN PRE AND POSTOPERATIVE OF BARIATRIC SURGERY: PRIVATE VS PUBLIC NETWORK

    PubMed Central

    NASCIMENTO, Taianne Machado; ALVES-JÚNIOR, Antônio; NUNES, Marco Antonio Prado; de FREITAS, Tiago Rodrigo Pereira; da SILVA, Marco Antonio Fontes Sarmento; ALVES, Maria Rosa Melo

    2015-01-01

    Background: Obesity is associated to several comorbidities, including nonalcoholic fatty liver disease, which implicates in isolated steatosis to steatohepatitis. The latter may progress to severe manifestations such as liver fibrosis, cirrhosis and hepatocellular carcinoma. Aim: To compare the presence of advanced liver fibrosis before and after bariatric surgery in patients of private and public health system. Methods: Patients from public and privative networks were studied before and after bariatric surgery. The presence or absence of advanced hepatic fibrosis was evaluated by NAFLD Fibrosis Score, a non-invasive method that uses age, BMI, AST/ALT ratio, albumin, platelet count and the presence or absence of hyperglycemia or diabetes. The characteristics of the two groups were compared. The established statistical significance criterion was p<0.05. Results: Were analyzed 40 patients with a mean age of 34.6±9.5 years for private network and 40.6± 10.2 years for public. The study sample, 35% were treated at private health system and 65% in the public ones, 38% male and 62% female. Preoperatively in the private network one (7.1%) patient had advanced liver fibrosis and developed to the absence of liver fibrosis after surgery. In the public eight (30.8%) patients had advanced liver fibrosis preoperatively, and at one year after the proportion fell to six (23%). Conclusion: The non-alcoholic fatty liver disease in its advanced form is more prevalent in obese patients treated in the public network than in the treated at the private network and bariatric surgery may be important therapeutic option in both populations. PMID:26734800

  10. Survey and assessment of electric and magnetic field (EMF) public exposure in the transportation environment

    SciTech Connect

    Dietrich, F.M.; Jacobs, W.L.

    1999-03-01

    This research, conducted under the support of the Federal Electric and Magnetic Field Research and Public Information Dissemination (EMF RAPID) Engineering Program, characterized the extreme-low-frequency (ELF) electric and magnetic fields (EMF) which a traveler might encounter while using various forms of transportation. Extensive measurement of field level, frequency, temporal variability and spatial variability are reported for: conventional internal-combustion cars, trucks and buses; electric cars, trucks and buses; commuter trains; ferry boats; jetliners; airport shuttle trams; and escalators and moving sidewalks. Static magnetic field levels are also reported. Where possible, the source of the fields is identified. This effort extends extensive past work which investigated field in electrified trains, subways, light rail vehicles, and a magnetically levitated train by using similar protocols to characterize the complex ELF (3 Hz to 3000 Hz) electric and magnetic fields found in virtually all transportation systems.

  11. Development of user guidelines for ECAS display design. Volume 2: Tasks 9 and 10. [educating the public to the benefits of spacelab and the space transportation system

    NASA Technical Reports Server (NTRS)

    Bathurst, D. B.

    1979-01-01

    Lay-oriented speakers aids, articles, a booklet, and a press kit were developed to inform the press and the general public with background information on the space transportation system, Spacelab, and Spacelab 1 experiments. Educational materials relating to solar-terrestrial physics and its potential benefits to mankind were also written. A basic network for distributing audiovisual and printed materials to regional secondary schools and universities was developed. Suggested scripts to be used with visual aids describing materials science and technology and astronomy and solar physics are presented.

  12. The Role of Personality Traits through Habit and Intention on Determining Future Preferences of Public Transport Use

    PubMed Central

    Yazdanpanah, Mahdi; Hadji Hosseinlou, Mansour

    2017-01-01

    A complex set of factors may affect transportation mode choice. While earlier studies have often considered objective factors in determining preferences of public transport use as a sustainable transportation, subjective factors such as personality traits are underexplored. Therefore, this study aimed to investigate the influence of personality traits on the number of future public transport use. Additionally, “car habit” and “intention toward using public modes” were considered to be important. For this purpose, a case study from departure passengers at Imam Khomeini International Airport (IKIA, Tehran, Iran) was conducted between January and February 2015 at IKIA. Results of structural equation modeling (SEM) shows that only neuroticism and extraversion personality traits were significant in determining future public transportation mode choice. However, the model indicates that these traits indirectly influence intention and car habit. Neuroticism was found to have a total effect of −0.022 on future public transport use, which represents a negative association with public transport use, while extraversion positively influenced future public transport use with a total effect of 0.031. Moreover, the results found interestingly that car access had a better fit to the data than the number of cars in household (NCH); both had significant positive effect on car habit, but only car access had a significant influence on intention. Furthermore, the effect of socio-demographic variables such as age, gender, educational level, income level, and body mass index (BMI) were determined to be significant in identifying choice of future transport mode to airports, which is explained in the discussion section of this paper. PMID:28218641

  13. The Role of Personality Traits through Habit and Intention on Determining Future Preferences of Public Transport Use.

    PubMed

    Yazdanpanah, Mahdi; Hadji Hosseinlou, Mansour

    2017-02-17

    A complex set of factors may affect transportation mode choice. While earlier studies have often considered objective factors in determining preferences of public transport use as a sustainable transportation, subjective factors such as personality traits are underexplored. Therefore, this study aimed to investigate the influence of personality traits on the number of future public transport use. Additionally, "car habit" and "intention toward using public modes" were considered to be important. For this purpose, a case study from departure passengers at Imam Khomeini International Airport (IKIA, Tehran, Iran) was conducted between January and February 2015 at IKIA. Results of structural equation modeling (SEM) shows that only neuroticism and extraversion personality traits were significant in determining future public transportation mode choice. However, the model indicates that these traits indirectly influence intention and car habit. Neuroticism was found to have a total effect of -0.022 on future public transport use, which represents a negative association with public transport use, while extraversion positively influenced future public transport use with a total effect of 0.031. Moreover, the results found interestingly that car access had a better fit to the data than the number of cars in household (NCH); both had significant positive effect on car habit, but only car access had a significant influence on intention. Furthermore, the effect of socio-demographic variables such as age, gender, educational level, income level, and body mass index (BMI) were determined to be significant in identifying choice of future transport mode to airports, which is explained in the discussion section of this paper.

  14. Informatics technology mimics ecology: dense, mutualistic collaboration networks are associated with higher publication rates.

    PubMed

    Sorani, Marco D

    2012-01-01

    Information technology (IT) adoption enables biomedical research. Publications are an accepted measure of research output, and network models can describe the collaborative nature of publication. In particular, ecological networks can serve as analogies for publication and technology adoption. We constructed network models of adoption of bioinformatics programming languages and health IT (HIT) from the literature.We selected seven programming languages and four types of HIT. We performed PubMed searches to identify publications since 2001. We calculated summary statistics and analyzed spatiotemporal relationships. Then, we assessed ecological models of specialization, cooperativity, competition, evolution, biodiversity, and stability associated with publications.Adoption of HIT has been variable, while scripting languages have experienced rapid adoption. Hospital systems had the largest HIT research corpus, while Perl had the largest language corpus. Scripting languages represented the largest connected network components. The relationship between edges and nodes was linear, though Bioconductor had more edges than expected and Perl had fewer. Spatiotemporal relationships were weak. Most languages shared a bioinformatics specialization and appeared mutualistic or competitive. HIT specializations varied. Specialization was highest for Bioconductor and radiology systems. Specialization and cooperativity were positively correlated among languages but negatively correlated among HIT. Rates of language evolution were similar. Biodiversity among languages grew in the first half of the decade and stabilized, while diversity among HIT was variable but flat. Compared with publications in 2001, correlation with publications one year later was positive while correlation after ten years was weak and negative.Adoption of new technologies can be unpredictable. Spatiotemporal relationships facilitate adoption but are not sufficient. As with ecosystems, dense, mutualistic

  15. Informatics Technology Mimics Ecology: Dense, Mutualistic Collaboration Networks Are Associated with Higher Publication Rates

    PubMed Central

    Sorani, Marco D.

    2012-01-01

    Information technology (IT) adoption enables biomedical research. Publications are an accepted measure of research output, and network models can describe the collaborative nature of publication. In particular, ecological networks can serve as analogies for publication and technology adoption. We constructed network models of adoption of bioinformatics programming languages and health IT (HIT) from the literature. We selected seven programming languages and four types of HIT. We performed PubMed searches to identify publications since 2001. We calculated summary statistics and analyzed spatiotemporal relationships. Then, we assessed ecological models of specialization, cooperativity, competition, evolution, biodiversity, and stability associated with publications. Adoption of HIT has been variable, while scripting languages have experienced rapid adoption. Hospital systems had the largest HIT research corpus, while Perl had the largest language corpus. Scripting languages represented the largest connected network components. The relationship between edges and nodes was linear, though Bioconductor had more edges than expected and Perl had fewer. Spatiotemporal relationships were weak. Most languages shared a bioinformatics specialization and appeared mutualistic or competitive. HIT specializations varied. Specialization was highest for Bioconductor and radiology systems. Specialization and cooperativity were positively correlated among languages but negatively correlated among HIT. Rates of language evolution were similar. Biodiversity among languages grew in the first half of the decade and stabilized, while diversity among HIT was variable but flat. Compared with publications in 2001, correlation with publications one year later was positive while correlation after ten years was weak and negative. Adoption of new technologies can be unpredictable. Spatiotemporal relationships facilitate adoption but are not sufficient. As with ecosystems, dense, mutualistic

  16. Physics of transportation: Towards optimal capacity using the multilayer network framework

    PubMed Central

    Du, Wen-Bo; Zhou, Xing-Lian; Jusup, Marko; Wang, Zhen

    2016-01-01

    Because of the critical role of transportation in modern times, one of the most successful application areas of statistical physics of complex networks is the study of traffic dynamics. However, the vast majority of works treat transportation networks as an isolated system, which is inconsistent with the fact that many complex networks are interrelated in a nontrivial way. To mimic a realistic scenario, we use the framework of multilayer networks to construct a two-layered traffic model, whereby the upper layer provides higher transport speed than the lower layer. Moreover, passengers are guided to travel along the path of minimal travelling time and with the additional cost they can transfer from one layer to another to avoid congestion and/or reach the final destination faster. By means of numerical simulations, we show that a degree distribution-based strategy, although facilitating the cooperation between both layers, can be further improved by enhancing the critical generating rate of passengers using a particle swarm optimisation (PSO) algorithm. If initialised with the prior knowledge from the degree distribution-based strategy, the PSO algorithm converges considerably faster. Our work exemplifies how statistical physics of complex networks can positively affect daily life. PMID:26791580

  17. Network Theory: A Primer and Questions for Air Transportation Systems Applications

    NASA Technical Reports Server (NTRS)

    Holmes, Bruce J.

    2004-01-01

    A new understanding (with potential applications to air transportation systems) has emerged in the past five years in the scientific field of networks. This development emerges in large part because we now have a new laboratory for developing theories about complex networks: The Internet. The premise of this new understanding is that most complex networks of interest, both of nature and of human contrivance, exhibit a fundamentally different behavior than thought for over two hundred years under classical graph theory. Classical theory held that networks exhibited random behavior, characterized by normal, (e.g., Gaussian or Poisson) degree distributions of the connectivity between nodes by links. The new understanding turns this idea on its head: networks of interest exhibit scale-free (or small world) degree distributions of connectivity, characterized by power law distributions. The implications of scale-free behavior for air transportation systems include the potential that some behaviors of complex system architectures might be analyzed through relatively simple approximations of local elements of the system. For air transportation applications, this presentation proposes a framework for constructing topologies (architectures) that represent the relationships between mobility, flight operations, aircraft requirements, and airspace capacity, and the related externalities in airspace procedures and architectures. The proposed architectures or topologies may serve as a framework for posing comparative and combinative analyses of performance, cost, security, environmental, and related metrics.

  18. Physics of transportation: Towards optimal capacity using the multilayer network framework

    NASA Astrophysics Data System (ADS)

    Du, Wen-Bo; Zhou, Xing-Lian; Jusup, Marko; Wang, Zhen

    2016-01-01

    Because of the critical role of transportation in modern times, one of the most successful application areas of statistical physics of complex networks is the study of traffic dynamics. However, the vast majority of works treat transportation networks as an isolated system, which is inconsistent with the fact that many complex networks are interrelated in a nontrivial way. To mimic a realistic scenario, we use the framework of multilayer networks to construct a two-layered traffic model, whereby the upper layer provides higher transport speed than the lower layer. Moreover, passengers are guided to travel along the path of minimal travelling time and with the additional cost they can transfer from one layer to another to avoid congestion and/or reach the final destination faster. By means of numerical simulations, we show that a degree distribution-based strategy, although facilitating the cooperation between both layers, can be further improved by enhancing the critical generating rate of passengers using a particle swarm optimisation (PSO) algorithm. If initialised with the prior knowledge from the degree distribution-based strategy, the PSO algorithm converges considerably faster. Our work exemplifies how statistical physics of complex networks can positively affect daily life.

  19. Physics of transportation: Towards optimal capacity using the multilayer network framework.

    PubMed

    Du, Wen-Bo; Zhou, Xing-Lian; Jusup, Marko; Wang, Zhen

    2016-01-21

    Because of the critical role of transportation in modern times, one of the most successful application areas of statistical physics of complex networks is the study of traffic dynamics. However, the vast majority of works treat transportation networks as an isolated system, which is inconsistent with the fact that many complex networks are interrelated in a nontrivial way. To mimic a realistic scenario, we use the framework of multilayer networks to construct a two-layered traffic model, whereby the upper layer provides higher transport speed than the lower layer. Moreover, passengers are guided to travel along the path of minimal travelling time and with the additional cost they can transfer from one layer to another to avoid congestion and/or reach the final destination faster. By means of numerical simulations, we show that a degree distribution-based strategy, although facilitating the cooperation between both layers, can be further improved by enhancing the critical generating rate of passengers using a particle swarm optimisation (PSO) algorithm. If initialised with the prior knowledge from the degree distribution-based strategy, the PSO algorithm converges considerably faster. Our work exemplifies how statistical physics of complex networks can positively affect daily life.

  20. Spatial-temporal data model and fractal analysis of transportation network in GIS environment

    NASA Astrophysics Data System (ADS)

    Feng, Yongjiu; Tong, Xiaohua; Li, Yangdong

    2008-10-01

    How to organize transportation data characterized by multi-time, multi-scale, multi-resolution and multi-source is one of the fundamental problems of GIS-T development. A spatial-temporal data model for GIS-T is proposed based on Spatial-temporal- Object Model. Transportation network data is systemically managed using dynamic segmentation technologies. And then a spatial-temporal database is built to integrally store geographical data of multi-time for transportation. Based on the spatial-temporal database, functions of spatial analysis of GIS-T are substantively extended. Fractal module is developed to improve the analyzing in intensity, density, structure and connectivity of transportation network based on the validation and evaluation of topologic relation. Integrated fractal with GIS-T strengthens the functions of spatial analysis and enriches the approaches of data mining and knowledge discovery of transportation network. Finally, the feasibility of the model and methods are tested thorough Guangdong Geographical Information Platform for Highway Project.

  1. dfnWorks: A discrete fracture network framework for modeling subsurface flow and transport

    DOE PAGES

    Hyman, Jeffrey D.; Karra, Satish; Makedonska, Nataliia; ...

    2015-11-01

    DFNWORKS is a parallelized computational suite to generate three-dimensional discrete fracture networks (DFN) and simulate flow and transport. Developed at Los Alamos National Laboratory over the past five years, it has been used to study flow and transport in fractured media at scales ranging from millimeters to kilometers. The networks are created and meshed using DFNGEN, which combines FRAM (the feature rejection algorithm for meshing) methodology to stochastically generate three-dimensional DFNs with the LaGriT meshing toolbox to create a high-quality computational mesh representation. The representation produces a conforming Delaunay triangulation suitable for high performance computing finite volume solvers in anmore » intrinsically parallel fashion. Flow through the network is simulated in dfnFlow, which utilizes the massively parallel subsurface flow and reactive transport finite volume code PFLOTRAN. A Lagrangian approach to simulating transport through the DFN is adopted within DFNTRANS to determine pathlines and solute transport through the DFN. Example applications of this suite in the areas of nuclear waste repository science, hydraulic fracturing and CO2 sequestration are also included.« less

  2. dfnWorks: A discrete fracture network framework for modeling subsurface flow and transport

    SciTech Connect

    Hyman, Jeffrey D.; Karra, Satish; Makedonska, Nataliia; Gable, Carl W.; Painter, Scott L.; Viswanathan, Hari S.

    2015-11-01

    DFNWORKS is a parallelized computational suite to generate three-dimensional discrete fracture networks (DFN) and simulate flow and transport. Developed at Los Alamos National Laboratory over the past five years, it has been used to study flow and transport in fractured media at scales ranging from millimeters to kilometers. The networks are created and meshed using DFNGEN, which combines FRAM (the feature rejection algorithm for meshing) methodology to stochastically generate three-dimensional DFNs with the LaGriT meshing toolbox to create a high-quality computational mesh representation. The representation produces a conforming Delaunay triangulation suitable for high performance computing finite volume solvers in an intrinsically parallel fashion. Flow through the network is simulated in dfnFlow, which utilizes the massively parallel subsurface flow and reactive transport finite volume code PFLOTRAN. A Lagrangian approach to simulating transport through the DFN is adopted within DFNTRANS to determine pathlines and solute transport through the DFN. Example applications of this suite in the areas of nuclear waste repository science, hydraulic fracturing and CO2 sequestration are also included.

  3. Squeezing a gel to establish network structure-transport property relationships

    NASA Astrophysics Data System (ADS)

    Chan, Edwin; Nadermann, Nichole; McLeod, Kelly; Tew, Greg

    2015-03-01

    Gels are used in many applications, ranging from drug delivery to water purification, where regulating transport of a particular permeant is critical. The structure of the gel determines its transport properties but developing the gel structure-transport property relationships often require multiple measurement techniques. In this work, we demonstrate poroelastic relaxation indentation (PRI) as a single measurement tool to establish the relationships between the polymer network structure and the transport properties of well-defined hydrogel networks synthesized via a thiol-norbornene click reaction of poly(ethylene glycol) (PEG) chains. We use PRI to quantify the mechanical and transport properties of a series of ``click'' hydrogels with different crosslink densities. By applying various thermodynamic network swelling models to the describe the mechanical response of these gels as measured from PRI, we are able to extract thermodynamic parameters of these hydrogels including the Flory chi parameter and the mesh size. We validate our approach by comparing the thermodynamic parameters obtained from PRI with results from neutrons scattering studies of the same series of hydrogels.

  4. Public transit 1997: Planning, management, marketing and new technology. Transportation research record

    SciTech Connect

    1997-09-01

    Partial Contents: Transit Service Design and Operation Practices in Western European Countries; Understanding Differences in Public Transit: Comparison of Boston and Toronto; Influence of the Metropolitan Atlanta Rapid Transit Authority on Population and Employment Location; Integrated Decision Support Tool for Evaluating Transit and Land-Use Coordination Policies; Transit Friendliness Factor: Approach to Quantifying Transit Access Environment in a Transportation Planning Model; Pedestrian Access to Transit: Model of Walk Trips and Their Design and Urban Form Determinants Around Bay Area Rapid Transit Stations; Parking Supply Policy and Transit Use: Case Study of Atlanta, Georgia; Mobility Analysis of Transit Systems; Research on Customer Requirements for Transit Service Design and Delivery.

  5. Governing Software: Networks, Databases and Algorithmic Power in the Digital Governance of Public Education

    ERIC Educational Resources Information Center

    Williamson, Ben

    2015-01-01

    This article examines the emergence of "digital governance" in public education in England. Drawing on and combining concepts from software studies, policy and political studies, it identifies some specific approaches to digital governance facilitated by network-based communications and database-driven information processing software…

  6. Networking and Managers' Career Success in the Malaysian Public Sector: The Moderating Effect of Managerial Level

    ERIC Educational Resources Information Center

    Rasdi, Roziah Mohd; Garavan, Thomas N.; Ismail, Maimunah

    2012-01-01

    Purpose: The purpose of this paper is to investigate how managerial level moderates the relationships between networking behaviours and career success (objective and subjective) in the context of a public sector organisation in Malaysia. Design/methodology/approach: The study utilised a cross-sectional design and investigated these relationships…

  7. Linking Transnational Logics: A Feminist Rhetorical Analysis of Public Policy Networks

    ERIC Educational Resources Information Center

    Dingo, Rebecca

    2008-01-01

    In this article, the author investigates the circulation and appropriation of representations of women in public policy. The author effectively mobilizes the metaphor of the network to examine the discursive intersections and transnational links between U.S. welfare programs and the World Bank gender mainstreaming policies. Her analysis reveals…

  8. 76 FR 10295 - Implementing a Nationwide, Broadband, Interoperable Public Safety Network in the 700 MHz Band

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-24

    ..., namely (1) Internet access; (2) Virtual Private Network (VPN) access to any authorized site and to home... additional requirements to further promote and enable nationwide interoperability among public safety... the instructions for submitting comments. Agency Web Site: http://www.fcc.gov . Follow...

  9. Impact of carbon nanotube length on electron transport in aligned carbon nanotube networks

    SciTech Connect

    Lee, Jeonyoon; Stein, Itai Y.; Devoe, Mackenzie E.; Lewis, Diana J.; Lachman, Noa; Buschhorn, Samuel T.; Wardle, Brian L.; Kessler, Seth S.

    2015-02-02

    Here, we quantify the electron transport properties of aligned carbon nanotube (CNT) networks as a function of the CNT length, where the electrical conductivities may be tuned by up to 10× with anisotropies exceeding 40%. Testing at elevated temperatures demonstrates that the aligned CNT networks have a negative temperature coefficient of resistance, and application of the fluctuation induced tunneling model leads to an activation energy of ≈14 meV for electron tunneling at the CNT-CNT junctions. Since the tunneling activation energy is shown to be independent of both CNT length and orientation, the variation in electron transport is attributed to the number of CNT-CNT junctions an electron must tunnel through during its percolated path, which is proportional to the morphology of the aligned CNT network.

  10. The Loss of Efficiency Caused by Agents’ Uncoordinated Routing in Transport Networks

    PubMed Central

    Wang, Junjie; Wang, Pu

    2014-01-01

    Large-scale daily commuting data were combined with detailed geographical information system (GIS) data to analyze the loss of transport efficiency caused by drivers’ uncoordinated routing in urban road networks. We used Price of Anarchy (POA) to quantify the loss of transport efficiency and found that both volume and distribution of human mobility demand determine the POA. In order to reduce POA, a small number of highways require considerable decreases in traffic, and their neighboring arterial roads need to attract more traffic. The magnitude of the adjustment in traffic flow can be estimated using the fundamental measure traffic flow only, which is widely available and easy to collect. Surprisingly, the most congested roads or the roads with largest traffic flow were not those requiring the most reduction of traffic. This study can offer guidance for the optimal control of urban traffic and facilitate improvements in the efficiency of transport networks. PMID:25349995

  11. The loss of efficiency caused by agents' uncoordinated routing in transport networks.

    PubMed

    Xu, Zhongzhi; Sun, Li; Wang, Junjie; Wang, Pu

    2014-01-01

    Large-scale daily commuting data were combined with detailed geographical information system (GIS) data to analyze the loss of transport efficiency caused by drivers' uncoordinated routing in urban road networks. We used Price of Anarchy (POA) to quantify the loss of transport efficiency and found that both volume and distribution of human mobility demand determine the POA. In order to reduce POA, a small number of highways require considerable decreases in traffic, and their neighboring arterial roads need to attract more traffic. The magnitude of the adjustment in traffic flow can be estimated using the fundamental measure traffic flow only, which is widely available and easy to collect. Surprisingly, the most congested roads or the roads with largest traffic flow were not those requiring the most reduction of traffic. This study can offer guidance for the optimal control of urban traffic and facilitate improvements in the efficiency of transport networks.

  12. A Health Impact Assessment of Proposed Public Transportation Service Cuts and Fare Increases in Boston, Massachusetts (U.S.A.)

    PubMed Central

    James, Peter; Ito, Kate; Buonocore, Jonathan J.; Levy, Jonathan I.; Arcaya, Mariana C.

    2014-01-01

    Transportation decisions have health consequences that are often not incorporated into policy-making processes. Health Impact Assessment (HIA) is a process that can be used to evaluate health effects of transportation policy. We present a rapid HIA, conducted over eight weeks, evaluating health and economic effects of proposed fare increases and service cuts to Boston, Massachusetts’ public transportation system. We used transportation modeling in concert with tools allowing for quantification and monetization of multiple pathways. We estimated health and economic costs of proposed public transportation system changes to be hundreds of millions of dollars per year, exceeding the budget gap the public transportation authority was required to close. Significant health pathways included crashes, air pollution, and physical activity. The HIA enabled stakeholders to advocate for more modest fare increases and service cuts, which were eventually adopted by decision makers. This HIA was among the first to quantify and monetize multiple pathways linking transportation decisions with health and economic outcomes, using approaches that could be applied in different settings. Including health costs in transportation decisions can lead to policy choices with both economic and public health benefits. PMID:25105550

  13. A health impact assessment of proposed public transportation service cuts and fare increases in Boston, Massachusetts (U.S.A.).

    PubMed

    James, Peter; Ito, Kate; Buonocore, Jonathan J; Levy, Jonathan I; Arcaya, Mariana C

    2014-08-07

    Transportation decisions have health consequences that are often not incorporated into policy-making processes. Health Impact Assessment (HIA) is a process that can be used to evaluate health effects of transportation policy. We present a rapid HIA, conducted over eight weeks, evaluating health and economic effects of proposed fare increases and service cuts to Boston, Massachusetts' public transportation system. We used transportation modeling in concert with tools allowing for quantification and monetization of multiple pathways. We estimated health and economic costs of proposed public transportation system changes to be hundreds of millions of dollars per year, exceeding the budget gap the public transportation authority was required to close. Significant health pathways included crashes, air pollution, and physical activity. The HIA enabled stakeholders to advocate for more modest fare increases and service cuts, which were eventually adopted by decision makers. This HIA was among the first to quantify and monetize multiple pathways linking transportation decisions with health and economic outcomes, using approaches that could be applied in different settings. Including health costs in transportation decisions can lead to policy choices with both economic and public health benefits.

  14. Rural Rides--A Practical Handbook for Starting and Operating A Rural Public Transportation System. Program Aid Number 1215.

    ERIC Educational Resources Information Center

    Department of Agriculture, Washington, DC. Farmers Home Administration.

    The transportation needs of the 30% of the population living in rural America, particularly those of the elderly, handicapped, poor, isolated, young, carless, and unemployed, are more critical than the needs of their counterparts in urban areas because of the lack of rural public transportation. Yet, only about 1% of the capitol federal investment…

  15. Strategic network design of Java Island fuel supply with production-transportation solution

    NASA Astrophysics Data System (ADS)

    Dianawati, Fauzia; Farizal, -; Surjandari, Isti; Marzuli, Rully

    2011-10-01

    This study aims to find more efficient supply network, from refineries / imports to fuel terminal, which still uses the Tanker, Tank Trucks or Rail Tank Wagon with an alternative pipeline that are considered more efficient than other transport modes, as well as gaining pipeline transportation network optimization analysis tailored to the capabilities/ capacity of refinery production and capacity of the pipe mode. With the complexity of the number of 3 point sources of supply, 19 destination of terminal, 4 kinds of products and 4 types of transport modes, transport-production model modified by adding multi-modal transport and investment costs of new pipeline. Then coded in Lingo program which adopts Branch & Bound technique and input the processed data in order to obtain an optimal distribution pattern produced the lowest distribution costs. This B&B solution was also compared with SCO solution which is a metaheuristic method. The results of this study lead to the development of new modes of pipeline connections in amount of 4 alternatives, generated from the optimal solution, but still potentially earned savings of about IDR 1 Trillion per year from cost-efficiency of product procurement and transportation costs.

  16. Network formation, governance, and evolution in public health: The North American Quitline Consortium case

    PubMed Central

    Provan, Keith G.; Beagles, Jonathan E.; Leischow, Scott J.

    2014-01-01

    Background Collaborative networks of health organizations have received a great deal of attention in recent years as a way of enhancing the flow of information and coordination of services. However, relatively little is known about how such networks are formed and evolve, especially outside a local, community-based setting. This article is an in-depth discussion of the evolution of the North American Quitline Consortium (NAQC). The NAQC is a network of U.S. and Canadian organizations that provide telephone-based counseling and related services to people trying to quit smoking. Methodology The research draws on data from interviews, documents, and a survey of NAQC members to assess how the network emerged, became formalized, and effectively governed. Findings The findings provide an understanding of how multiregional public health networks evolve, while building on and extending the broader literature on organizational networks in other sectors and settings. Specifically, we found that the network form that ultimately emerged was a product of the back-and-forth interplay between the internal needs and goals of those organizations that would ultimately become network members, in this case, state-, and provincial-level tobacco quitline organizations. We also found that network formation, and then governance through a network administrative organization, was driven by important events and shifts in the external environment, including the impact and influence of major national organizations. Practice Implications The results of the study provide health care leaders and policy officials an understanding of how the activities of a large number of organizations having a common health goal, but spanning multiple states and countries, might be coordinated and integrated through the establishment of a formal network. PMID:21712725

  17. Evolving Transport Networks With Cellular Automata Models Inspired by Slime Mould.

    PubMed

    Tsompanas, Michail-Antisthenis I; Sirakoulis, Georgios Ch; Adamatzky, Andrew I

    2015-09-01

    Man-made transport networks and their design are closely related to the shortest path problem and considered amongst the most debated problems of computational intelligence. Apart from using conventional or bio-inspired computer algorithms, many researchers tried to solve this kind of problem using biological computing substrates, gas-discharge solvers, prototypes of a mobile droplet, and hot ice computers. In this aspect, another example of biological computer is the plasmodium of acellular slime mould Physarum polycephalum (P. polycephalum), which is a large single cell visible by an unaided eye and has been proven as a reliable living substrate for implementing biological computing devices for computational geometry, graph-theoretical problems, and optimization and imitation of transport networks. Although P. polycephalum is easy to experiment with, computing devices built with the living slime mould are extremely slow; it takes slime mould days to execute a computation. Consequently, mapping key computing mechanisms of the slime mould onto silicon would allow us to produce efficient bio-inspired computing devices to tackle with hard to solve computational intelligence problems like the aforementioned. Toward this direction, a cellular automaton (CA)-based, Physarum-inspired, network designing model is proposed. This novel CA-based model is inspired by the propagating strategy, the formation of tubular networks, and the computing abilities of the plasmodium of P. polycephalum. The results delivered by the CA model demonstrate a good match with several previously published results of experimental laboratory studies on imitation of man-made transport networks with P. polycephalum. Consequently, the proposed CA model can be used as a virtual, easy-to-access, and biomimicking laboratory emulator that will economize large time periods needed for biological experiments while producing networks almost identical to the tubular networks of the real-slime mould.

  18. Review of Regulatory Emphasis on Transportation Safety in the United States, 2002-2009: Public versus Private Modes.

    PubMed

    Waycaster, Garrett C; Matsumura, Taiki; Bilotkach, Volodymyr; Haftka, Raphael T; Kim, Nam H

    2017-01-17

    The U.S. Department of Transportation is responsible for implementing new safety improvements and regulations with the goal of ensuring limited funds are distributed to where they can have the greatest impact on safety. In this work, we conduct a study of new regulations and other reactions (such as recalls) to fatal accidents in several different modes of transportation implemented from 2002 to 2009. We find that in the safest modes of commercial aviation and bus transport, the amount of spending on new regulations is high in relation to the number of fatalities compared to the regulatory attention received by less safe modes of general aviation and private automobiles. Additionally, we study two major fatal accident investigations from commercial aviation and two major automotive recalls associated with fatal accidents. We find differences in the cost per expected fatality prevented for these reactions, with the airline accident investigations being more cost effective. Overall, we observe trends in both the automotive and aviation sectors that suggest that public transportation receives more regulatory attention than private transport. We also observe that the types of safety remedies utilized, regulation versus investigation, have varying levels of effectiveness in different transport modes. We suggest that these differences are indicative of increased public demand for safety in modes where a third party may be held responsible, even for those not participating in the transportation. These findings have important implications for the transportation industry, policymakers, and for estimating the public demand for safety in new transport modes.

  19. Travel Behavior Change in Older Travelers: Understanding Critical Reactions to Incidents Encountered in Public Transport

    PubMed Central

    Sundling, Catherine

    2015-01-01

    Accessibility of travel may be better understood if psychological factors underlying change in travel behavior are known. This paper examines older (65+) travelers’ motives for changing their travel behavior. These changes are grounded in critical incidents earlier encountered in public-transport travel. A scientific framework is developed based on cognitive and behavioral theory. In 29 individual interviews, travelers’ critical reactions (i.e., cognitive, emotional, and/or behavioral) to 77 critical incidents were examined. By applying critical incident technique (CIT), five reaction themes were identified that had generated travel-behavior change: firm restrictions, unpredictability, unfair treatment, complicated trips, and earlier adverse experiences. To improve older travelers’ access to public transport, key findings were: (a) service must be designed so as to strengthen the feeling of being in control throughout the journey; (b) extended personal service would increase predictability in the travel chain and decrease travel complexity; consequently, (c) when designing new services and making effective accessibility interventions, policy makers should consider and utilize underlying psychological factors that could direct traveler behavior. PMID:26593935

  20. Heterogeneity of passenger exposure to air pollutants in public transport microenvironments

    NASA Astrophysics Data System (ADS)

    Yang, Fenhuan; Kaul, Daya; Wong, Ka Chun; Westerdahl, Dane; Sun, Li; Ho, Kin-fai; Tian, Linwei; Brimblecombe, Peter; Ning, Zhi

    2015-05-01

    Epidemiologic studies have linked human exposure to pollutants with adverse health effects. Passenger exposure in public transport systems contributes an important fraction of daily burden of air pollutants. While there is extensive literature reporting the concentrations of pollutants in public transport systems in different cities, there are few studies systematically addressing the heterogeneity of passenger exposure in different transit microenvironments, in cabins of different transit vehicles and in areas with different characteristics. The present study investigated PM2.5 (particulate matter with aerodynamic diameters smaller than 2.5 μm), black carbon (BC), ultrafine particles (UFP) and carbon monoxide (CO) pollutant concentrations in various public road transport systems in highly urbanized city of Hong Kong. Using a trolley case housing numerous portable air monitors, we conducted a total of 119 trips during the campaign. Transit microenvironments, classified as 1). busy and secondary roadside bus stops; 2). open and enclosed termini; 3). above- and under-ground Motor Rail Transport (MTR) platforms, were investigated and compared to identify the factors that may affect passenger exposures. The pollutants inside bus and MTR cabins were also investigated together with a comparison of time integrated exposure between the transit modes. Busy roadside and enclosed termini demonstrated the highest average particle concentrations while the lowest was found on the MTR platforms. Traffic-related pollutants BC, UFP and CO showed larger variations than PM2.5 across different microenvironments and areas confirming their heterogeneity in urban environments. In-cabin pollutant concentrations showed distinct patterns with BC and UFP high in diesel bus cabins and CO high in LPG bus cabins, suggesting possible self-pollution issues and/or penetration of on-road pollutants inside cabins during bus transit. The total passenger exposure along selected routes, showed bus

  1. Influence of large changes in public transportation (Transantiago) on the black carbon pollution near streets

    NASA Astrophysics Data System (ADS)

    Gramsch, E.; Le Nir, G.; Araya, M.; Rubio, M. A.; Moreno, F.; Oyola, P.

    2013-02-01

    In 2006 a large transformation was carried out on the public transportation system in Santiago de Chile. The original system (before 2006) had hundreds of bus owners with about 7000 diesel buses. The new system has only 13 firms with about 5900 buses which operate in different parts of the city with little overlap between them. In this work we evaluate the impact of the Transantiago system on the black carbon pollution along four roads directly affected by the modification to the transport system. Measurements were carried out during May-July of 2005 (before Transantiago) and June-July of 2007 (after Transantiago). We have used the Wilcoxon rank-sum test to evaluate black carbon concentration in four streets in year 2005 and 2007. The results show that a statistically significant reduction between year 2005 (before Transantiago) and year 2007 (after Transantiago) in Alameda street, which changed from a mean of 18.8 μg m-3 in 2005 to 11.9 μg m-3 in 2007. In this street there was a decrease in the number of buses as well as the number of private vehicles and an improvement in the technology of public transportation between those years. Other two streets (Usach and Departamental) did not change or experienced a small increase in the black carbon concentration in spite of having less flux of buses in 2007. Eliodoro Yañez Street, which did not have public transportation in 2005 or 2007 experienced a 15% increase in the black carbon concentration between those years. Analysis of the data indicates that the change is related to a decrease in the total number of vehicles or the number of other diesel vehicles in the street rather than a decrease in the number of buses only. 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.

  2. Bundling dynamics regulates the active mechanics and transport in carbon nanotube networks and their nanocomposites

    NASA Astrophysics Data System (ADS)

    Hahm, Myung Gwan; Wang, Hailong; Jung, Hyun Young; Hong, Sanghyun; Lee, Sung-Goo; Kim, Sung-Ryong; Upmanyu, Moneesh; Jung, Yung Joon

    2012-05-01

    High-density carbon nanotube networks (CNNs) continue to attract interest as active elements in nanoelectronic devices, nanoelectromechanical systems (NEMS) and multifunctional nanocomposites. The interplay between the network nanostructure and its properties is crucial, yet current understanding remains limited to the passive response. Here, we employ a novel superstructure consisting of millimeter-long vertically aligned single walled carbon nanotubes (SWCNTs) sandwiched between polydimethylsiloxane (PDMS) layers to quantify the effect of two classes of mechanical stimuli, film densification and stretching, on the electronic and thermal transport across the network. The network deforms easily with an increase in the electrical and thermal conductivities, suggestive of a floppy yet highly reconfigurable network. Insight from atomistically informed coarse-grained simulations uncover an interplay between the extent of lateral assembly of the bundles, modulated by surface zipping/unzipping, and the elastic energy associated with the bent conformations of the nanotubes/bundles. During densification, the network becomes highly interconnected yet we observe a modest increase in bundling primarily due to the reduced spacing between the SWCNTs. The stretching, on the other hand, is characterized by an initial debundling regime as the strain accommodation occurs via unzipping of the branched interconnects, followed by rapid rebundling as the strain transfers to the increasingly aligned bundles. In both cases, the increase in the electrical and thermal conductivity is primarily due to the increase in bundle size; the changes in network connectivity have a minor effect on the transport. Our results have broad implications for filamentous networks of inorganic nanoassemblies composed of interacting tubes, wires and ribbons/belts.High-density carbon nanotube networks (CNNs) continue to attract interest as active elements in nanoelectronic devices, nanoelectromechanical systems

  3. Plasma networking in magnetically confined plasmas and diagnostics of nonlocal heat transport in tokamak filamentary plasmas

    NASA Astrophysics Data System (ADS)

    Kukushkin, A. B.; Rantsev-Kartinov, V. A.

    1999-02-01

    The method of multilevel dynamical contrasting is applied to analyzing available data from tokamak plasmas. The results illustrate a possibility of extending the concept of the plasma percolating networks in dense Z pinches (and other inertially confined plasmas) to the case of magnetically confined plasmas. This extension suggests a necessity to append the conventional picture of the nonfilamentary plasma (which is nearly a fluid described by conventional magnetohydrodynamics) with a "network" component which is formed by the strongest long-living filaments of electric current and penetrate the "fluid" component. Signs of networking are found in visible light and soft x-ray images, and magnetic probing data. A diagnostic algorithm is formulated for identifying the role of plasma networking in observed phenomena of nonlocal (non-diffusive) heat transport in a tokamak.

  4. Efficient packet transportation on complex networks with nonuniform node capacity distribution

    NASA Astrophysics Data System (ADS)

    He, Xuan; Niu, Kai; He, Zhiqiang; Lin, Jiaru; Jiang, Zhong-Yuan

    2015-03-01

    Provided that node delivery capacity may be not uniformly distributed in many realistic networks, we present a node delivery capacity distribution in which each node capacity is composed of uniform fraction and degree related proportion. Based on the node delivery capacity distribution, we construct a novel routing mechanism called efficient weighted routing (EWR) strategy to enhance network traffic capacity and transportation efficiency. Compared with the shortest path routing and the efficient routing strategies, the EWR achieves the highest traffic capacity. After investigating average path length, network diameter, maximum efficient betweenness, average efficient betweenness, average travel time and average traffic load under extensive simulations, it indicates that the EWR appears to be a very effective routing method. The idea of this routing mechanism gives us a good insight into network science research. The practical use of this work is prospective in some real complex systems such as the Internet.

  5. Anomalous diffusion and the structure of human transportation networks

    NASA Astrophysics Data System (ADS)

    Brockmann, D.

    2008-04-01

    The dispersal of individuals of a species is the key driving force of various spatiotemporal phenomena which occur on geographical scales. It can synchronise populations of interacting species, stabilise them, and diversify gene pools [1-3]. The geographic spread of human infectious diseases such as influenza, measles and the recent severe acute respiratory syndrome (SARS) is essentially promoted by human travel which occurs on many length scales and is sustained by a variety of means of transportation [4-8]. In the light of increasing international trade, intensified human traffic, and an imminent influenza A pandemic the knowledge of dynamical and statistical properties of human dispersal is of fundamental importance and acute [7,9,10]. A quantitative statistical theory for human travel and concomitant reliable forecasts would substantially improve and extend existing prevention strategies. Despite its crucial role, a quantitative assessment of human dispersal remains elusive and the opinion that humans disperse diffusively still prevails in many models [11]. In this chapter I will report on a recently developed technique which permits a solid and quantitative assessment of human dispersal on geographical scales [11]. The key idea is to infer the statistical properties of human travel by analysing the geographic circulation of individual bank notes for which comprehensive datasets are collected at the online bill-tracking website www.wheresgeorge.com. The analysis shows that the distribution of travelling distances decays as a power law, indicating that the movement of bank notes is reminiscent of superdiffusive, scale free random walks known as Lèvy flights [13]. Secondly, the probability of remaining in a small, spatially confined region for a time T is dominated by heavy tails which attenuate superdiffusive dispersal. I will show that the dispersal of bank notes can be described on many spatiotemporal scales by a two parameter continuous time random walk

  6. [General Practitioner Sentinel Network as a Tool of [Public] Health Surveillance].

    PubMed

    Rodrigues, Ana Paula; Fonseca, Rita Carvalho; Matias-Dias, Carlos

    2016-01-01

    Current strategies of European health advocate the strengthening of the role of public health, requiring from decision-makers the ability to defend and enhance the health of individuals and populations in all policies. In the pursuit of this objective, public health should be evidence-based and so public health surveillance, seen as an important tool of public health since the nineteenth century, plays a central role in public health practice through the production and dissemination of the health information necessary for health planning and for evaluation of public health actions. Within the practice of public health estimations of disease frequency are important for outbreak control, health assessment, health needs assessment and estimation of health gains, but unfortunately these estimations are not always available for the entire population. In those cases and for diseases with high prevalence sentinel surveillance based in sentinel networks have some advantages for specific groups, namely needed of scarce resources and obtainment of quick results.The central role of family doctors in chronic disease management, their knowledge on individuals and families and their responsibilities in the management of a clear defined patients list are characteristics that make general practice an appropriate context to develop a sentinel network. In fact, in Portugal there is a general practitioner sentinel network named Rede Médicos-Sentinela working since 1989 which estimated, for the last 25 years, incidence rates of several chronic diseases, some of them targeted on national priority health programs. Thus, we consider that Rede Médicos-Sentinela can be integrated in a national surveillance system for chronic diseases in Portugal.

  7. Disorder and dephasing as control knobs for light transport in optical fiber cavity networks

    NASA Astrophysics Data System (ADS)

    Viciani, Silvia; Gherardini, Stefano; Lima, Manuela; Bellini, Marco; Caruso, Filippo

    2016-11-01

    Transport phenomena represent a very interdisciplinary topic with applications in many fields of science, such as physics, chemistry, and biology. In this context, the possibility to design a perfectly controllable experimental setup, where to tune and optimize its dynamics parameters, is a challenging but very relevant task to emulate, for instance, the transmission of energy in light harvesting processes. Here, we experimentally build a scalable and controllable transport emulator based on optical fiber cavity networks where the system noise parameters can be finely tuned while maximizing the transfer efficiency. In particular, we demonstrate that disorder and dephasing noise are two control knobs allowing one to play with constructive and destructive interference to optimize the transport paths towards an exit site. These optical setups, on one side, mimic the transport dynamics in natural photosynthetic organisms and, on the other, are very promising platforms to artificially design optimal nanoscale structures for novel, more efficient, clean energy technologies.

  8. Disorder and dephasing as control knobs for light transport in optical fiber cavity networks

    PubMed Central

    Viciani, Silvia; Gherardini, Stefano; Lima, Manuela; Bellini, Marco; Caruso, Filippo

    2016-01-01

    Transport phenomena represent a very interdisciplinary topic with applications in many fields of science, such as physics, chemistry, and biology. In this context, the possibility to design a perfectly controllable experimental setup, where to tune and optimize its dynamics parameters, is a challenging but very relevant task to emulate, for instance, the transmission of energy in light harvesting processes. Here, we experimentally build a scalable and controllable transport emulator based on optical fiber cavity networks where the system noise parameters can be finely tuned while maximizing the transfer efficiency. In particular, we demonstrate that disorder and dephasing noise are two control knobs allowing one to play with constructive and destructive interference to optimize the transport paths towards an exit site. These optical setups, on one side, mimic the transport dynamics in natural photosynthetic organisms and, on the other, are very promising platforms to artificially design optimal nanoscale structures for novel, more efficient, clean energy technologies. PMID:27886246

  9. Sequential Measurement of Intermodal Variability in Public Transportation PM2.5 and CO Exposure Concentrations.

    PubMed

    Che, W W; Frey, H Christopher; Lau, Alexis K H

    2016-08-16

    A sequential measurement method is demonstrated for quantifying the variability in exposure concentration during public transportation. This method was applied in Hong Kong by measuring PM2.5 and CO concentrations along a route connecting 13 transportation-related microenvironments within 3-4 h. The study design takes into account ventilation, proximity to local sources, area-wide air quality, and meteorological conditions. Portable instruments were compacted into a backpack to facilitate measurement under crowded transportation conditions and to quantify personal exposure by sampling at nose level. The route included stops next to three roadside monitors to enable comparison of fixed site and exposure concentrations. PM2.5 exposure concentrations were correlated with the roadside monitors, despite differences in averaging time, detection method, and sampling location. Although highly correlated in temporal trend, PM2.5 concentrations varied significantly among microenvironments, with mean concentration ratios versus roadside monitor ranging from 0.5 for MTR train to 1.3 for bus terminal. Measured inter-run variability provides insight regarding the sample size needed to discriminate between microenvironments with increased statistical significance. The study results illustrate the utility of sequential measurement of microenvironments and policy-relevant insights for exposure mitigation and management.

  10. Why Does Public Transport Not Arrive on Time? The Pervasiveness of Equal Headway Instability

    PubMed Central

    Gershenson, Carlos; Pineda, Luis A.

    2009-01-01

    Background The equal headway instability phenomenon is pervasive in public transport systems. This instability is characterized by an aggregation of vehicles that causes inefficient service. While equal headway instability is common, it has not been studied independently of a particular scenario. However, the phenomenon is apparent in many transport systems and can be modeled and rectified in abstraction. Methodology We present a multi-agent simulation where a default method with no restrictions always leads to unstable headways. We discuss two methods that attempt to achieve equal headways, called minimum and maximum. Since one parameter of the methods depends on the passenger density, adaptive versions—where the relevant parameter is adjusted automatically—are also put forward. Our results show that the adaptive maximum method improves significantly over the default method. The model and simulation give insights of the interplay between transport design and passenger behavior. Finally, we provide technological and social suggestions for engineers and passengers to help achieve equal headways and thus reduce delays. Conclusions The equal headway instability phenomenon can be avoided with the suggested technological and social measures. PMID:19862321

  11. Public health benefits of strategies to reduce greenhouse-gas emissions: urban land transport.

    PubMed

    Woodcock, James; Edwards, Phil; Tonne, Cathryn; Armstrong, Ben G; Ashiru, Olu; Banister, David; Beevers, Sean; Chalabi, Zaid; Chowdhury, Zohir; Cohen, Aaron; Franco, Oscar H; Haines, Andy; Hickman, Robin; Lindsay, Graeme; Mittal, Ishaan; Mohan, Dinesh; Tiwari, Geetam; Woodward, Alistair; Roberts, Ian

    2009-12-05

    We used Comparative Risk Assessment methods to estimate the health effects of alternative urban land transport scenarios for two settings-London, UK, and Delhi, India. For each setting, we compared a business-as-usual 2030 projection (without policies for reduction of greenhouse gases) with alternative scenarios-lower-carbon-emission motor vehicles, increased active travel, and a combination of the two. We developed separate models that linked transport scenarios with physical activity, air pollution, and risk of road traffic injury. In both cities, we noted that reduction in carbon dioxide emissions through an increase in active travel and less use of motor vehicles had larger health benefits per million population (7332 disability-adjusted life-years [DALYs] in London, and 12 516 in Delhi in 1 year) than from the increased use of lower-emission motor vehicles (160 DALYs in London, and 1696 in Delhi). However, combination of active travel and lower-emission motor vehicles would give the largest benefits (7439 DALYs in London, 12 995 in Delhi), notably from a reduction in the number of years of life lost from ischaemic heart disease (10-19% in London, 11-25% in Delhi). Although uncertainties remain, climate change mitigation in transport should benefit public health substantially. Policies to increase the acceptability, appeal, and safety of active urban travel, and discourage travel in private motor vehicles would provide larger health benefits than would policies that focus solely on lower-emission motor vehicles.

  12. Backstepping fuzzy-neural-network control design for hybrid maglev transportation system.

    PubMed

    Wai, Rong-Jong; Yao, Jing-Xiang; Lee, Jeng-Dao

    2015-02-01

    This paper focuses on the design of a backstepping fuzzy-neural-network control (BFNNC) for the online levitated balancing and propulsive positioning of a hybrid magnetic levitation (maglev) transportation system. The dynamic model of the hybrid maglev transportation system including levitated hybrid electromagnets to reduce the suspension power loss and the friction force during linear movement and a propulsive linear induction motor based on the concepts of mechanical geometry and motion dynamics is first constructed. The ultimate goal is to design an online fuzzy neural network (FNN) control methodology to cope with the problem of the complicated control transformation and the chattering control effort in backstepping control (BSC) design, and to directly ensure the stability of the controlled system without the requirement of strict constraints, detailed system information, and auxiliary compensated controllers despite the existence of uncertainties. In the proposed BFNNC scheme, an FNN control is utilized to be the major control role by imitating the BSC strategy, and adaptation laws for network parameters are derived in the sense of projection algorithm and Lyapunov stability theorem to ensure the network convergence as well as stable control performance. The effectiveness of the proposed control strategy for the hybrid maglev transportation system is verified by experimental results, and the superiority of the BFNNC scheme is indicated in comparison with the BSC strategy and the backstepping particle-swarm-optimization control system in previous research.

  13. Modeling sediment transport after ditch network maintenance of a forested peatland

    NASA Astrophysics Data System (ADS)

    Haahti, K.; Marttila, H.; Warsta, L.; Kokkonen, T.; Finér, L.; Koivusalo, H.

    2016-11-01

    Elevated suspended sediment (SS) loads released from peatlands after drainage operations and the resulting negative effect on the ecological status of the receiving water bodies have been widely recognized. Understanding the processes controlling erosion and sediment transport within the ditch network forms a prerequisite for adequate sediment control. While numerous experimental studies have been reported in this field, model based assessments are rare. This study presents a modeling approach to investigate sediment transport in a peatland ditch network. The transport model describes bed erosion, rain-induced bank erosion, floc deposition, and consolidation of the bed. Coupled to a distributed hydrological model, sediment transport was simulated in a 5.2 ha forestry-drained peatland catchment for 2 years after ditch cleaning. Comparing simulation results to measured SS concentrations suggested that the loose peat material, produced during excavation, contributed markedly to elevated SS concentrations immediately after ditch cleaning. Both snowmelt and summer rainstorms contributed critically to annual loads. Springtime peat erosion during snowmelt was driven by ditch flow whereas during summer rainfalls, bank erosion by raindrop impact was identified as an important process. Relating modeling results to observed spatial topographic changes in the ditch network was challenging and the results were difficult to verify. Nevertheless, the model has potential to identify risk areas for erosion. The results demonstrate that modeling is effective in separating the importance of different processes and complements pure experimental approaches. Modeling results can aid planning and designing efficient sediment control measures and guide the focus of experimental studies.

  14. Self-Learning Intelligent Agents for Dynamic Traffic Routing on Transportation Networks

    NASA Astrophysics Data System (ADS)

    Sadek, Add; Basha, Nagi

    Intelligent Transportation Systems (ITS) are designed to take advantage of recent advances in communications, electronics, and Information Technology in improving the efficiency and safety of transportation systems. Among the several ITS applications is the notion of Dynamic Traffic Routing (DTR), which involves generating "optimal" routing recommendations to drivers with the aim of maximizing network utilizing. In this paper, we demonstrate the feasibility of using a self-learning intelligent agent to solve the DTR problem to achieve traffic user equilibrium in a transportation network. The core idea is to deploy an agent to a simulation model of a highway. The agent then learns by itself by interacting with the simulation model. Once the agent reaches a satisfactory level of performance, it can then be deployed to the real-world, where it would continue to learn how to refine its control policies over time. To test this concept in this paper, the Cell Transmission Model (CTM) developed by Carlos Daganzo of the University of California at Berkeley is used to simulate a simple highway with two main alternative routes. With the model developed, a Reinforcement Learning Agent (RLA) is developed to learn how to best dynamically route traffic, so as to maximize the utilization of existing capacity. Preliminary results obtained from our experiments are promising. RL, being an adaptive online learning technique, appears to have a great potential for controlling a stochastic dynamic systems such as a transportation system. Furthermore, the approach is highly scalable and applicable to a variety of networks and roadways.

  15. Advanced public transportation systems: The state of the art, update `96. Final report, July 1995-December 1996

    SciTech Connect

    Casey, R.F.; Labell, L.N.; Holmstrom, R.; LoVecchio, J.A.; Schweiger, C.L.

    1996-01-01

    This report documents work performed under FTA`s Advanced Public Transportation Systems (APTS) Program, a program structured to undertake research and development of innovative applications of advanced navigation, information, and communication technologies that most benefit public transportation. This report is the latest in a series of State-of-the-Art reports, the last of which was published in January 1994. It contains the results of an investigation of the extent of adoption of advanced technology in the provision of public transportation service in North America. It focused on some of the most innovative or comprehensive implementations, categorized under four types of services/technologies: Fleet Management, Traveler Information, Electronic Fare Payment, and Transportation Demand Management.

  16. Quantitative characterization of the microstructure and transport properties of biopolymer networks

    NASA Astrophysics Data System (ADS)

    Jiao, Yang; Torquato, Salvatore

    2012-06-01

    Biopolymer networks are of fundamental importance to many biological processes in normal and tumorous tissues. In this paper, we employ the panoply of theoretical and simulation techniques developed for characterizing heterogeneous materials to quantify the microstructure and effective diffusive transport properties (diffusion coefficient De and mean survival time τ) of collagen type I networks at various collagen concentrations. In particular, we compute the pore-size probability density function P(δ) for the networks and present a variety of analytical estimates of the effective diffusion coefficient De for finite-sized diffusing particles, including the low-density approximation, the Ogston approximation and the Torquato approximation. The Hashin-Strikman upper bound on the effective diffusion coefficient De and the pore-size lower bound on the mean survival time τ are used as benchmarks to test our analytical approximations and numerical results. Moreover, we generalize the efficient first-passage-time techniques for Brownian-motion simulations in suspensions of spheres to the case of fiber networks and compute the associated effective diffusion coefficient De as well as the mean survival time τ, which is related to nuclear magnetic resonance relaxation times. Our numerical results for De are in excellent agreement with analytical results for simple network microstructures, such as periodic arrays of parallel cylinders. Specifically, the Torquato approximation provides the most accurate estimates of De for all collagen concentrations among all of the analytical approximations we consider. We formulate a universal curve for τ for the networks at different collagen concentrations, extending the work of Torquato and Yeong (1997 J. Chem. Phys. 106 8814). We apply rigorous cross-property relations to estimate the effective bulk modulus of collagen networks from a knowledge of the effective diffusion coefficient computed here. The use of cross-property relations

  17. Quantitative characterization of the microstructure and transport properties of biopolymer networks.

    PubMed

    Jiao, Yang; Torquato, Salvatore

    2012-06-01

    Biopolymer networks are of fundamental importance to many biological processes in normal and tumorous tissues. In this paper, we employ the panoply of theoretical and simulation techniques developed for characterizing heterogeneous materials to quantify the microstructure and effective diffusive transport properties (diffusion coefficient D(e) and mean survival time τ) of collagen type I networks at various collagen concentrations. In particular, we compute the pore-size probability density function P(δ) for the networks and present a variety of analytical estimates of the effective diffusion coefficient D(e) for finite-sized diffusing particles, including the low-density approximation, the Ogston approximation and the Torquato approximation. The Hashin-Strikman upper bound on the effective diffusion coefficient D(e) and the pore-size lower bound on the mean survival time τ are used as benchmarks to test our analytical approximations and numerical results. Moreover, we generalize the efficient first-passage-time techniques for Brownian-motion simulations in suspensions of spheres to the case of fiber networks and compute the associated effective diffusion coefficient D(e) as well as the mean survival time τ, which is related to nuclear magnetic resonance relaxation times. Our numerical results for D(e) are in excellent agreement with analytical results for simple network microstructures, such as periodic arrays of parallel cylinders. Specifically, the Torquato approximation provides the most accurate estimates of D(e) for all collagen concentrations among all of the analytical approximations we consider. We formulate a universal curve for τ for the networks at different collagen concentrations, extending the work of Torquato and Yeong (1997 J. Chem. Phys. 106 8814). We apply rigorous cross-property relations to estimate the effective bulk modulus of collagen networks from a knowledge of the effective diffusion coefficient computed here. The use of cross

  18. Analog and digital transport of RF channels over converged 5G wireless-optical networks

    NASA Astrophysics Data System (ADS)

    Binh, Le Nguyen

    2016-02-01

    Under the exponential increase demand by the emerging 5G wireless access networking and thus data-center based Internet, novel and economical transport of RF channels to and from wireless access systems. This paper presents the transport technologies of RF channels over the analog and digital domain so as to meet the demands of the transport capacity reaching multi-Tbps, in the followings: (i) The convergence of 5G broadband wireless and optical networks and its demands on capacity delivery and network structures; (ii) Analog optical technologies for delivery of both the information and RF carriers to and from multiple-input multiple-output (MIMO) antenna sites so as to control the beam steering of MIMO antenna in the mmW at either 28.6 GHz and 56.8 GHz RF carrier and delivery of channels of aggregate capacity reaching several Tbps; (ii) Transceiver employing advanced digital modulation formats and digital signal processing (DSP) so as to provide 100G and beyond transmission rate to meet the ultra-high capacity demands with flexible spectral grids, hence pay-on-demand services. The interplay between DSP-based and analog transport techniques is examined; (iii) Transport technologies for 5G cloud access networks and associate modulation and digital processing techniques for capacity efficiency; and (iv) Finally the integrated optic technologies with novel lasers, comb generators and simultaneous dual function photonic devices for both demultiplexing/multiplexing and modulation are proposed, hence a system on chip structure can be structured. Quantum dot lasers and matrixes of micro ring resonators are integrated on the same Si-on-Silica substrate are proposed and described.

  19. Cooperation and Contagion in Web-Based, Networked Public Goods Experiments

    PubMed Central

    Suri, Siddharth; Watts, Duncan J.

    2011-01-01

    A longstanding idea in the literature on human cooperation is that cooperation should be reinforced when conditional cooperators are more likely to interact. In the context of social networks, this idea implies that cooperation should fare better in highly clustered networks such as cliques than in networks with low clustering such as random networks. To test this hypothesis, we conducted a series of web-based experiments, in which 24 individuals played a local public goods game arranged on one of five network topologies that varied between disconnected cliques and a random regular graph. In contrast with previous theoretical work, we found that network topology had no significant effect on average contributions. This result implies either that individuals are not conditional cooperators, or else that cooperation does not benefit from positive reinforcement between connected neighbors. We then tested both of these possibilities in two subsequent series of experiments in which artificial seed players were introduced, making either full or zero contributions. First, we found that although players did generally behave like conditional cooperators, they were as likely to decrease their contributions in response to low contributing neighbors as they were to increase their contributions in response to high contributing neighbors. Second, we found that positive effects of cooperation were contagious only to direct neighbors in the network. In total we report on 113 human subjects experiments, highlighting the speed, flexibility, and cost-effectiveness of web-based experiments over those conducted in physical labs. PMID:21412431

  20. Cooperation and contagion in web-based, networked public goods experiments.

    PubMed

    Suri, Siddharth; Watts, Duncan J

    2011-03-11

    A longstanding idea in the literature on human cooperation is that cooperation should be reinforced when conditional cooperators are more likely to interact. In the context of social networks, this idea implies that cooperation should fare better in highly clustered networks such as cliques than in networks with low clustering such as random networks. To test this hypothesis, we conducted a series of web-based experiments, in which 24 individuals played a local public goods game arranged on one of five network topologies that varied between disconnected cliques and a random regular graph. In contrast with previous theoretical work, we found that network topology had no significant effect on average contributions. This result implies either that individuals are not conditional cooperators, or else that cooperation does not benefit from positive reinforcement between connected neighbors. We then tested both of these possibilities in two subsequent series of experiments in which artificial seed players were introduced, making either full or zero contributions. First, we found that although players did generally behave like conditional cooperators, they were as likely to decrease their contributions in response to low contributing neighbors as they were to increase their contributions in response to high contributing neighbors. Second, we found that positive effects of cooperation were contagious only to direct neighbors in the network. In total we report on 113 human subjects experiments, highlighting the speed, flexibility, and cost-effectiveness of web-based experiments over those conducted in physical labs.

  1. Sensing Models and Sensor Network Architectures for Transport Infrastructure Monitoring in Smart Cities

    NASA Astrophysics Data System (ADS)

    Simonis, Ingo

    2015-04-01

    Transport infrastructure monitoring and analysis is one of the focus areas in the context of smart cities. With the growing number of people moving into densely populated urban metro areas, precise tracking of moving people and goods is the basis for profound decision-making and future planning. With the goal of defining optimal extensions and modifications to existing transport infrastructures, multi-modal transport has to be monitored and analysed. This process is performed on the basis of sensor networks that combine a variety of sensor models, types, and deployments within the area of interest. Multi-generation networks, consisting of a number of sensor types and versions, are causing further challenges for the integration and processing of sensor observations. These challenges are not getting any smaller with the development of the Internet of Things, which brings promising opportunities, but is currently stuck in a type of protocol war between big industry players from both the hardware and network infrastructure domain. In this paper, we will highlight how the OGC suite of standards, with the Sensor Web standards developed by the Sensor Web Enablement Initiative together with the latest developments by the Sensor Web for Internet of Things community can be applied to the monitoring and improvement of transport infrastructures. Sensor Web standards have been applied in the past to pure technical domains, but need to be broadened now in order to meet new challenges. Only cross domain approaches will allow to develop satisfying transport infrastructure approaches that take into account requirements coming form a variety of sectors such as tourism, administration, transport industry, emergency services, or private people. The goal is the development of interoperable components that can be easily integrated within data infrastructures and follow well defined information models to allow robust processing.

  2. Synaptic GABA release prevents GABA transporter type-1 reversal during excessive network activity

    PubMed Central

    Savtchenko, Leonid; Megalogeni, Maria; Rusakov, Dmitri A.; Walker, Matthew C.; Pavlov, Ivan

    2015-01-01

    GABA transporters control extracellular GABA, which regulates the key aspects of neuronal and network behaviour. A prevailing view is that modest neuronal depolarization results in GABA transporter type-1 (GAT-1) reversal causing non-vesicular GABA release into the extracellular space during intense network activity. This has important implications for GABA uptake-targeting therapies. Here we combined a realistic kinetic model of GAT-1 with experimental measurements of tonic GABAA receptor currents in ex vivo hippocampal slices to examine GAT-1 operation under varying network conditions. Our simulations predict that synaptic GABA release during network activity robustly prevents GAT-1 reversal. We test this in the 0 Mg2+ model of epileptiform discharges using slices from healthy and chronically epileptic rats and find that epileptiform activity is associated with increased synaptic GABA release and is not accompanied by GAT-1 reversal. We conclude that sustained efflux of GABA through GAT-1 is unlikely to occur during physiological or pathological network activity. PMID:25798861

  3. Research on the Best Time to Intervene into Network Public Opinion for Managers -Based on "Nankai Buick Affair"-

    NASA Astrophysics Data System (ADS)

    Chen, Meiyang; Liu, Yijun

    This study is based on network public opinion of the case - ”Nankai Buick Affair”. The daily number of posts as the variable, quantitative research is carried out on the law of change in network public opinion, which provides the scientific basis for managers to choose the best time to intervene. This article first begins from the three aspects: a number of changes in daily posts over time, the constitute of main topics and statistical analysis, and then gives a in-depth analysis of the law of change in network public opinion. After the emergency, performed by the number of posts, the shape of the rise and fall in network public opinion has three categories: sharp peak, severe right-skewed and fat tail. On this basis, then we study the changes of major issues in network public opinion in different stages: In the two periods: “Start- Peak” and “Peak-End”, not only the number of posts in BBS is not the same, but also the main topics in the BBS articles are different for the network public opinion of emergency. Finally, points out, If the managers issue truth of the incident in the prime time through the channels of authority, we can reduce the distance between the peak and the state of equilibrium for the network public opinion system, which is conducive to a smooth landing public opinion and social harmony.

  4. Identifying a Statistical Model for North Dakota K-12 Public School Transportation Funding by Comparing Fifteen State Transportation Funding Formulas

    ERIC Educational Resources Information Center

    Holen, Steven M.

    2012-01-01

    The purpose of this study was to review the history of North Dakota K-12 transportation funding system, identify how school districts are reimbursed for transportation expenses, and compare this information with fourteen other state transportation funding systems. North Dakota utilizes a block grant structure that has been in place since 1972 and…

  5. Characteristics of the oil transport network in the South of Mexico

    NASA Astrophysics Data System (ADS)

    Juárez, R.; Fernández, I. Y.; Guzmán, L.

    2017-01-01

    We present a study of some organizational properties of the oil transport network of the Mexican oil company (PEMEX) in a region of the State of Tabasco. Particularly, the generalized centrality and the distribution of connectivities are calculated in order to evaluate some aspects of the structure of the network. We find that the connectivities (k) are characterized by a degree distribution which follows a power-law function of the form, P(k)~k ‑λ, with λ = 2.6. Moreover, our procedure permits to evalute the importance of lines (ducts) and nodes, which can be wells, production headers, separation batteries and petrochemical complexes.

  6. Performance Analysis of the AeroTP Transport Protocol for Highly-Dynamic Airborne Telemetry Networks

    DTIC Science & Technology

    2011-06-03

    Acknowledgment Options.” RFC 2018 (Proposed Standard ), Oct. 1996. [11] “The ns- 3 network simulator.” http://www.nsnam.org, July 2009. [12] M. AL-Enazi, S. A. Gogi...AFFTC-PA- 11146 Performance Analysis of the AeroTP Transport Protocol for Highly-Dynamic Airborne Telemetry Networks James P.G. Sterbenz...Kamakshi Sirisha Pathapati, Truc Anh N. Nguyen, Justin P. Rohrer AIR FORCE FLIGHT TEST CENTER EDWARDS AFB, CA JUNE 3 , 2011 A F F T C

  7. Does Network Geometry Influence the Electron Transport Dynamics in Mesoporous Nanoparticle Solar Cells?

    SciTech Connect

    Frank, A. J.; Benkstein, K. D.; Kopidakis, N.; van de Lagemaat, J.

    2003-05-01

    A major objective of our research is to define and solve the problems that limit the efficiency and commercial viability of solar cells based on dye-sensitized nanocrystalline TiO2. Toward this end, we are currently elucidating the factors that govern charge transport and the loss mechanisms in mesoporous nanoparticle films of TiO2. In this paper, we describe the first experimental evidence that the network geometry strongly influences electron transport and the first application of percolation theory to dye-sensitized solar cells.

  8. Accountability for All: What Voters Want from Education Candidates. 2002 Public Education Network/"Education Week" National Survey of Public Opinion.

    ERIC Educational Resources Information Center

    Editorial Projects in Education, Bethesda, MD.

    This report presents information from a national survey commissioned in January 2002 by the Public Education Network and Education Week. The poll examines the attitudes of American voters towards public schools and reveals what they want politicians to do about education once they are in office. Overall, Americans assign great value to public…

  9. Wisconsin’s Environmental Public Health Tracking Network: Information Systems Design for Childhood Cancer Surveillance

    PubMed Central

    Hanrahan, Lawrence P.; Anderson, Henry A.; Busby, Brian; Bekkedal, Marni; Sieger, Thomas; Stephenson, Laura; Knobeloch, Lynda; Werner, Mark; Imm, Pamela; Olson, Joseph

    2004-01-01

    In this article we describe the development of an information system for environmental childhood cancer surveillance. The Wisconsin Cancer Registry annually receives more than 25,000 incident case reports. Approximately 269 cases per year involve children. Over time, there has been considerable community interest in understanding the role the environment plays as a cause of these cancer cases. Wisconsin’s Public Health Information Network (WI-PHIN) is a robust web portal integrating both Health Alert Network and National Electronic Disease Surveillance System components. WI-PHIN is the information technology platform for all public health surveillance programs. Functions include the secure, automated exchange of cancer case data between public health–based and hospital-based cancer registrars; web-based supplemental data entry for environmental exposure confirmation and hypothesis testing; automated data analysis, visualization, and exposure–outcome record linkage; directories of public health and clinical personnel for role-based access control of sensitive surveillance information; public health information dissemination and alerting; and information technology security and critical infrastructure protection. For hypothesis generation, cancer case data are sent electronically to WI-PHIN and populate the integrated data repository. Environmental data are linked and the exposure–disease relationships are explored using statistical tools for ecologic exposure risk assessment. For hypothesis testing, case–control interviews collect exposure histories, including parental employment and residential histories. This information technology approach can thus serve as the basis for building a comprehensive system to assess environmental cancer etiology. PMID:15471739

  10. Equity at Scale: How Public Charter School Networks Can Innovate and Improve Services for Students with Disabilities

    ERIC Educational Resources Information Center

    O'Neill, Paul T.; Rhim, Lauren Morando

    2015-01-01

    When public charter schools first opened in the early 1990s, each was unique and independent. But as successful public charter schools continued to grow and expand their impact beyond a single site, and as organizations developed school designs that could be implemented at multiple locations, networks of public charter schools emerged. The public…

  11. Professional education and training in public health genomics: a working policy developed on behalf of the public health genomics European network.

    PubMed

    Burton, H; Adams, M

    2009-01-01

    Public health genomics (PHG) is an area of public health that is vital if we are to ensure that scientific advances in genomics are effectively and responsibly translated into public and health policies. Education and training in PHG for relevant professionals in public health and wider health and public policy was thus identified in 2006 as a key issue by the Public Health Genomics European Network (PHGEN). This paper provides an outline of the educational needs and practical proposals for the development of PHG education based on a resourced educational network that will undertake work on competences, the identification and sharing of current educational resources, and the development of programs in a variety of media and settings including highly specialist resources for researchers or individuals specializing in this area of policy.

  12. 76 FR 43355 - Public Comment and Public Meeting on Draft Revisions to the Transportation Element and Federal...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-20

    ... From the Federal Register Online via the Government Publishing Office NATIONAL CAPITAL PLANNING... Capital Planning Commission. ACTION: Notice of public comment period and public meeting. SUMMARY: The National Capital Planning Commission (NCPC), the Planning Commission for the Federal Government within...

  13. Quantum simulation via filtered Hamiltonian engineering: application to perfect quantum transport in spin networks.

    PubMed

    Ajoy, Ashok; Cappellaro, Paola

    2013-05-31

    We propose a method for Hamiltonian engineering that requires no local control but only relies on collective qubit rotations and field gradients. The technique achieves a spatial modulation of the coupling strengths via a dynamical construction of a weighting function combined with a Bragg grating. As an example, we demonstrate how to generate the ideal Hamiltonian for perfect quantum information transport between two separated nodes of a large spin network. We engineer a spin chain with optimal couplings starting from a large spin network, such as one naturally occurring in crystals, while decoupling all unwanted interactions. For realistic experimental parameters, our method can be used to drive almost perfect quantum information transport at room temperature. The Hamiltonian engineering method can be made more robust under decoherence and coupling disorder by a novel apodization scheme. Thus, the method is quite general and can be used to engineer the Hamiltonian of many complex spin lattices with different topologies and interactions.

  14. Explorations Around "Graceful Failure" in Transportation Infrastructure: Lessons Learned By the Infrastructure and Climate Network (ICNet)

    NASA Astrophysics Data System (ADS)

    Jacobs, J. M.; Thomas, N.; Mo, W.; Kirshen, P. H.; Douglas, E. M.; Daniel, J.; Bell, E.; Friess, L.; Mallick, R.; Kartez, J.; Hayhoe, K.; Croope, S.

    2014-12-01

    Recent events have demonstrated that the United States' transportation infrastructure is highly vulnerable to extreme weather events which will likely increase in the future. In light of the 60% shortfall of the $900 billion investment needed over the next five years to maintain this aging infrastructure, hardening of all infrastructures is unlikely. Alternative strategies are needed to ensure that critical aspects of the transportation network are maintained during climate extremes. Preliminary concepts around multi-tier service expectations of bridges and roads with reference to network capacity will be presented. Drawing from recent flooding events across the U.S., specific examples for roads/pavement will be used to illustrate impacts, disruptions, and trade-offs between performance during events and subsequent damage. This talk will also address policy and cultural norms within the civil engineering practice that will likely challenge the application of graceful failure pathways during extreme events.

  15. The Data Transport Network: A Usenet-Based Approach For Data Retrieval From Remote Field Sites

    NASA Astrophysics Data System (ADS)

    Valentic, T. A.

    2005-12-01

    The Data Transport Network coordinates the collection of scientific data, instrument telemetry and post-processing for the delivery of real-time results over the Internet from instruments located at remote field sites with limited or unreliable network connections. The system was originally developed in 1999 for the distribution of large data sets collected by the radar, lidars and imagers at the NSF upper atmosphere research facility in Sondrestrom, Greenland. The system helped to mitigate disruptions in network connectivity and optimized transfers over the site's low-bandwidth satellite link. The core idea behind the system is to transfer data files as attachments in Usenet messages. The messages collected by a local news server are periodically transmitted to other servers on the Internet when link conditions permit. If the network goes down, data files continue to be stored locally and the server will periodically attempt to deliver the files for upwards of two weeks. Using this simple approach, the Data Transport Network is able to handle a large number of independent data streams from multiple instruments. Each data stream is posted into a separate news group. There are no limitations to the types of data files that can be sent and the system uses standard Internet protocols for encoding, accessing and transmitting files. A common framework allows for new data collection or processing programs to be easily integrated. The two-way nature of the communications also allows for data to be delivered to the site as well, a feature used for the remote control of instruments. In recent years, the Data Transport Network has been applied to small, low-power embedded systems. Coupled with satellite-based communications systems such as Iridium, these miniature Data Transport servers have found application in a number of remote instrument deployments in the Arctic. SRI's involvement as a team member in Veco Polar Resources, the NSF Office of Polar Programs Arctic

  16. Suspended sediment transport trough a large fluvial-tidal channel network

    USGS Publications Warehouse

    Wright, Scott A.; Morgan-King, Tara L.

    2015-01-01

    The confluence of the Sacramento and San Joaquin Rivers, CA, forms a large network of interconnected channels, referred to as the Sacramento-San Joaquin Delta (the Delta). The Delta comprises the transition zone from the fluvial influences of the upstream rivers and tidal influences of San Francisco Bay downstream. Formerly an extensive tidal marsh, the hydrodynamics and geomorphology of Delta have been substantially modified by humans to support agriculture, navigation, and water supply. These modifications, including construction of new channels, diking and draining of tidal wetlands, dredging of navigation channels, and the operation of large pumping facilities for distribution of freshwater from the Delta to other parts of the state, have had a dramatic impact on the physical and ecological processes within the Delta. To better understand the current physical processes, and their linkages to ecological processes, the USGS maintains an extensive network of flow, sediment, and water quality gages in the Delta. Flow gaging is accomplished through use of the index-velocity method, and sediment monitoring uses turbidity as a surrogate for suspended-sediment concentration. Herein, we present analyses of the transport and dispersal of suspended sediment through the complex network of channels in the Delta. The primary source of sediment to the Delta is the Sacramento River, which delivers pulses of sediment primarily during winter and spring runoff events. Upon reaching the Delta, the sediment pulses move through the fluvial-tidal transition while also encountering numerous channel junctions as the Sacramento River branches into several distributary channels. The monitoring network allows us to track these pulses through the network and document the dominant transport pathways for suspended sediment. Further, the flow gaging allows for an assessment of the relative effects of advection (the fluvial signal) and dispersion (from the tides) on the sediment pulses as they

  17. One effective algorithm for finding a minimum cut of any transport network

    NASA Astrophysics Data System (ADS)

    Petrov, S. V.; Snezhin, A. N.; Prostokishin, V. M.

    2017-01-01

    Finding the minimal cut on the directed graph is an important task that has not yet been solved in a general form. The solution of this problem allows one to find “the pipeline bottleneck” of the transport network and manage changing flows efficiently. In this article, authors discussed a new algorithm for solving this problem, built on the basis of consideration of the corresponding dual problem.

  18. Evaluating the effect of internal aperture variability on transport in kilometer scale discrete fracture networks

    SciTech Connect

    Makedonska, Nataliia; Hyman, Jeffrey D.; Karra, Satish; Painter, Scott L.; Gable, Carl W.; Viswanathan, Hari S.

    2016-08-01

    The apertures of natural fractures in fractured rock are highly heterogeneous. However, in-fracture aperture variability is often neglected in flow and transport modeling and individual fractures are assumed to have uniform aperture distribution. The relative importance of in-fracture variability in flow and transport modeling within kilometer18 scale field–scale fracture networks has been under a matter of debate for a long time because the flow in each single fracture is controlled not only by in-fracture variability but also by boundary conditions. Computational limitations have previously prohibited researchers from investigating the relative importance of in-fracture variability in flow and transport modeling within large-scale fracture networks. We address this question by incorporating internal heterogeneity of individual fractures into 23 flow simulations within kilometer scale three-dimensional fracture networks, where fracture intensity, P32 (ratio between total fracture area and domain volume) is between 0.027 and 0.031 [1/m]. A recently developed discrete fracture network (DFN) simulation capability, dfnWorks, is used to generate DFNs that include in-fracture aperture variability represented by a stationary log-normal stochastic field with various correlation lengths and variances. The Lagrangian transport parameters, non-reacting travel time and cumulative retention, are calculated along particles streamlines. It is observed that due to local flow channeling early particle travel times are more sensitive to in-fracture variability than the tails of travel time distributions, where no significant effect of the in-fracture transmissivity variations and spatial correlation length is observed.

  19. Evaluating the effect of internal aperture variability on transport in kilometer scale discrete fracture networks

    DOE PAGES

    Makedonska, Nataliia; Hyman, Jeffrey D.; Karra, Satish; ...

    2016-08-01

    The apertures of natural fractures in fractured rock are highly heterogeneous. However, in-fracture aperture variability is often neglected in flow and transport modeling and individual fractures are assumed to have uniform aperture distribution. The relative importance of in-fracture variability in flow and transport modeling within kilometer18 scale field–scale fracture networks has been under a matter of debate for a long time because the flow in each single fracture is controlled not only by in-fracture variability but also by boundary conditions. Computational limitations have previously prohibited researchers from investigating the relative importance of in-fracture variability in flow and transport modeling withinmore » large-scale fracture networks. We address this question by incorporating internal heterogeneity of individual fractures into 23 flow simulations within kilometer scale three-dimensional fracture networks, where fracture intensity, P32 (ratio between total fracture area and domain volume) is between 0.027 and 0.031 [1/m]. A recently developed discrete fracture network (DFN) simulation capability, dfnWorks, is used to generate DFNs that include in-fracture aperture variability represented by a stationary log-normal stochastic field with various correlation lengths and variances. The Lagrangian transport parameters, non-reacting travel time and cumulative retention, are calculated along particles streamlines. It is observed that due to local flow channeling early particle travel times are more sensitive to in-fracture variability than the tails of travel time distributions, where no significant effect of the in-fracture transmissivity variations and spatial correlation length is observed.« less

  20. Did public health travel advice reach EURO 2012 football fans? A social network survey.

    PubMed

    Janiec, J; Zielicka-Hardy, A; Polkowska, A; Rogalska, J; Sadkowska-Todys, M

    2012-08-02

    We posted a survey on the Union of European Football Associations (UEFA)’s EURO 2012 Facebook profile to evaluate whether public health travel advice, specifically on the importance of measles vaccination,reached fans attending EURO 2012. Responses suggested that these messages were missed by 77% of fans. Social networks could serve as innovative platforms to conduct surveys, enabling rapid access to target populations at low cost and could be of use during upcoming mass gatherings such as the Olympics.

  1. A robust and energy-efficient transport protocol for cognitive radio sensor networks.

    PubMed

    Salim, Shelly; Moh, Sangman

    2014-10-20

    A cognitive radio sensor network (CRSN) is a wireless sensor network in which sensor nodes are equipped with cognitive radio. CRSNs benefit from cognitive radio capabilities such as dynamic spectrum access and transmission parameters reconfigurability; but cognitive radio also brings additional challenges and leads to higher energy consumption. Motivated to improve the energy efficiency in CRSNs, we propose a robust and energy-efficient transport protocol (RETP). The novelties of RETP are two-fold: (I) it combines distributed channel sensing and channel decision with centralized schedule-based data transmission; and (II) it differentiates the types of data transmission on the basis of data content and adopts different acknowledgment methods for different transmission types. To the best of our knowledge, no transport layer protocols have yet been designed for CRSNs. Simulation results show that the proposed protocol achieves remarkably longer network lifetime and shorter event-detection delay compared to those achieved with a conventional transport protocol, while simultaneously preserving event-detection reliability.

  2. 1D Unsteady Flow and Sediment Transport Model for Channel Network

    NASA Astrophysics Data System (ADS)

    bai, Y.; Duan, J. G.

    2012-12-01

    This paper presents a one-dimensional unsteady flow and sediment transport model for simulating flood routing and sediment transport over mobile alluvium in channel network. The modified St. Venant equation together with the suspended sediment and bed load transport equations are solved simultaneously to obtain flow properties and sediment transport rates. The Godunov-type finite volume method is employed, and the flux terms are discretized by using the upwind and the HLLC schemes. Then, the Exner equation is used to solve for bed elevation changes. In unsteady flow, sediment transport is non-equilibrium, therefore suspended load adaptation coefficient and bed load adaptation length are used to account for the difference between equilibrium and non-equilibrium sediment transport rate. At river confluences, water surface elevations are kept the same, and the law of mass conservation is used as the internal boundary conditions. An unprecedented flood event occurred in the Santa Cruz River, Tucson, Arizona, in July 2006, is used to test the performances of the model. Simulated results of water surface elevation and bed elevation changes show good agreements with the measurements.

  3. [Application of the network thermodynamics to interpretation of transport in a microsystems: transport of homogeneous solutions through polymeric membrane].

    PubMed

    Slezak, Andrzej

    2011-01-01

    The Kedem-Katchalsky equations, derived using symmetric and hybrid transformation of the Peusner's network transformation, to interpretation of transport through Nephrophan membrane of glucose aqueous solutions were employed. The values of Rij, Lij, Hij i Pij (i does not = j = 1, 2) coefficients were calculated. From these calculations it results that, the values of coefficients R12, L11 and H11 are independent on concentration (C). The values of residual coefficients are dependent on C: values of coefficients P11, L12, L22 and H22 increases linearly, while values of coefficients R22 and P22--hiperbolic decreases together with growth of C. In turn the coefficient H12 is negative and coefficients P11 and P12 are positive. The values of these coefficients decreases together with growth of C.

  4. Hybrid terrestrial/satellite networks and interoperability among public safety communication systems

    NASA Astrophysics Data System (ADS)

    Deobald, Brian M.

    2005-06-01

    A recent FCC decision1 has validated a new architecture with the potential to provide all of North America with an unusually broad and powerful wireless communications system. This architecture permits an existing allocation of mobile satellite spectrum to power a hybrid network, comprised of both terrestrial and satellite components. A satellite provides ubiquitous coverage, switching to a terrestrial-based cellular technology when in urban areas. The terrestrial component also provides capacity in areas of high demand. This ultra wide-area hybrid network, in turn, can act as a hub in an interlocking system of networks, incorporating public safety LMRs. The applicability of this system to homeland security should be obvious. It works nearly everywhere. It continues working even when towers are down throughout a wide area. It works with a conventional mobile device in a functionally transparent manner, providing first responders with interoperability, coverage, and redundancy needed to execute both their day-to-day and exigent responsibilities.

  5. Breast cancer publication network: profile of co-authorship and co-organization

    PubMed Central

    Biglu, Mohammad-Hossein; Abotalebi, Parvaneh; Ghavami, Mostafa

    2016-01-01

    Introduction: Breast cancer is one of the highest reasons of deaths for people in the world. The objective of current study is to analyze and visualize the trend of global scientific activities in the field of breast cancer during a period of 10 years through 2006-2015. Methods: The current study was performed by utilizing the scientometrics analysis and mapping the co-authorship and co-organization networks. The Web of Science Core Collection (WoS-CC)database was used to extract all papers indexed as a topic of breast cancer through 2006 to 2015. Research productivity was measured through analysis several parameters, including: the number and time course of publications, the journal and language of publications, the frequency and type of publications, as well as top 20 active sub-categories together with country contribution. The extracted data were transferred into the Excel charts and plotted as diagrams. The Science of Science (Sci2) and CiteSpace softwares were used as tools for mapping the co-authorship and co-organization networks of the published papers. Results: Analysis of data indicated that the number of publications in the field of breast cancer has linearly increased and correlated with the time-course of the study. The number of publication indexed in WoS-CC in 2015 was two times greater than that of 2006, which reached from 15 229 documents in 2006 to 30 667 documents in 2015. English Language accounted for 98% of total publications as the most dominant language. The vast majority of publications' type was in the form of original journal articles (64.7%). Based on Bradford scatterings law, the journal of "Cancer Research" was the most productive journal among the core journals, while the USA, China, and England were the most prolific countries in the field. The co-organization network indicated the dominant role of Harvard University in the field. Conclusion: The integrity of network indicated that scientists in the field of breast cancer

  6. Breast cancer publication network: profile of co-authorship and co-organization.

    PubMed

    Biglu, Mohammad-Hossein; Abotalebi, Parvaneh; Ghavami, Mostafa

    2016-01-01

    Introduction: Breast cancer is one of the highest reasons of deaths for people in the world. The objective of current study is to analyze and visualize the trend of global scientific activities in the field of breast cancer during a period of 10 years through 2006-2015. Methods: The current study was performed by utilizing the scientometrics analysis and mapping the co-authorship and co-organization networks. The Web of Science Core Collection (WoS-CC)database was used to extract all papers indexed as a topic of breast cancer through 2006 to 2015. Research productivity was measured through analysis several parameters, including: the number and time course of publications, the journal and language of publications, the frequency and type of publications, as well as top 20 active sub-categories together with country contribution. The extracted data were transferred into the Excel charts and plotted as diagrams. The Science of Science (Sci2) and CiteSpace softwares were used as tools for mapping the co-authorship and co-organization networks of the published papers. Results: Analysis of data indicated that the number of publications in the field of breast cancer has linearly increased and correlated with the time-course of the study. The number of publication indexed in WoS-CC in 2015 was two times greater than that of 2006, which reached from 15 229 documents in 2006 to 30 667 documents in 2015. English Language accounted for 98% of total publications as the most dominant language. The vast majority of publications' type was in the form of original journal articles (64.7%). Based on Bradford scatterings law, the journal of "Cancer Research" was the most productive journal among the core journals, while the USA, China, and England were the most prolific countries in the field. The co-organization network indicated the dominant role of Harvard University in the field. Conclusion: The integrity of network indicated that scientists in the field of breast cancer

  7. A selection model for accounting for publication bias in a full network meta-analysis.

    PubMed

    Mavridis, Dimitris; Welton, Nicky J; Sutton, Alex; Salanti, Georgia

    2014-12-30

    Copas and Shi suggested a selection model to explore the potential impact of publication bias via sensitivity analysis based on assumptions for the probability of publication of trials conditional on the precision of their results. Chootrakool et al. extended this model to three-arm trials but did not fully account for the implications of the consistency assumption, and their model is difficult to generalize for complex network structures with more than three treatments. Fitting these selection models within a frequentist setting requires maximization of a complex likelihood function, and identification problems are common. We have previously presented a Bayesian implementation of the selection model when multiple treatments are compared with a common reference treatment. We now present a general model suitable for complex, full network meta-analysis that accounts for consistency when adjusting results for publication bias. We developed a design-by-treatment selection model to describe the mechanism by which studies with different designs (sets of treatments compared in a trial) and precision may be selected for publication. We fit the model in a Bayesian setting because it avoids the numerical problems encountered in the frequentist setting, it is generalizable with respect to the number of treatments and study arms, and it provides a flexible framework for sensitivity analysis using external knowledge. Our model accounts for the additional uncertainty arising from publication bias more successfully compared to the standard Copas model or its previous extensions. We illustrate the methodology using a published triangular network for the failure of vascular graft or arterial patency.

  8. A TiO2 nanotube network electron transport layer for high efficiency perovskite solar cells.

    PubMed

    Gao, Xianfeng; Li, Jianyang; Gollon, Sam; Qiu, Ming; Guan, Dongsheng; Guo, Xiaoru; Chen, Junhong; Yuan, Chris

    2017-02-15

    The electron transport layer (ETL) plays a critical role in high efficiency perovskite solar cells. In this study, an anodic TiO2 nanotube film was transformed into a TiO2 nanotube network film, which maintained its advantage as an efficient ETL for perovskite solar cells. Compared with the mesoporous TiO2 nanoparticle ETL, the TiO2 nanotube network ETL can increase the efficiency of perovskite solar cells by 26.6%, which is attributed to its superior charge collection property and light trapping ability. The results confirm the importance of optimizing the electron collecting layer and suggest another way to design and fabricate novel perovskite solid state solar cells, potentially by using a TiO2 nanotube network film as an alternative high efficiency electrode.

  9. GENERAL: Connectivity correlations in three topological spaces of urban bus-transport networks in China

    NASA Astrophysics Data System (ADS)

    Chen, Yong-Zhou; Fu, Chun-Hua; Chang, Hui; Li, Nan; He, Da-Ren

    2008-10-01

    In this paper, an empirical investigation is presented, which focuses on unveiling the universality of connectivity correlations in three spaces (the route space, the stop geographical space and bus-transferring space) of urban bus-transport networks (BTNs) in four major cities of China. The underlying features of the connectivity correlations are shown in two statistical ways. One is the correlation between the (weighted) average degree of all the nearest neighbouring vertices with degree k, (Knnw (k)) Knn(k), and k, and the other is the correlations between the assortativity coefficient r and, respectively, the network size N, the network diameter D, the averaged clustering coefficient C, and the averaged distance . The obtained results show qualitatively the same connectivity correlations of all the considered cities under all the three spaces.

  10. Self-organized Balanced Resources in Random Networks with Transportation Bandwidths

    NASA Astrophysics Data System (ADS)

    Yeung, Chi Ho; Wong, K. Y. Michael

    We apply statistical physics to study the task of resource allocation in random networks with limited bandwidths for the transportation of resources along the links. We derive algorithms which searches the optimal solution without the need of a global optimizer. For networks with uniformly high connectivity, the resource shortage of a node becomes a well-defined function of its capacity. An efficient profile of the allocated resources is found, with clusters of node interconnected by an extensive fraction of unsaturated links, enabling the resource shortages among the nodes to remain balanced. The capacity-shortage relation exhibits features similar to the Maxwell’s construction. For scale-free networks, such an efficient profile is observed even for nodes of low connectivity.

  11. Three Dimensional Flow, Transport and Geomechanical Simulations in Discrete Fracture Network Under Condition of Uncertainty

    NASA Astrophysics Data System (ADS)

    Ryerson, F. J.; Ezzedine, S. M.; Glascoe, L. G.; Antoun, T. H.

    2011-12-01

    Fractures and fracture networks are the principle pathways for migration of water, heat and mass in enhanced geothermal systems, oil and gas reservoirs, CO2 leakage from saline aquifers, and radioactive and toxic industrial wastes from underground storage repositories. A major issue to overcome when characterizing a fractured reservoir is that of data limitation due to accessibility and affordability. Moreover, the ability to map discontinuities in the rock with available geological and geophysical tools tends to decrease particularly as the scale of the discontinuity goes down. Data collected are often reduced to probability distribution functions for predictive modeling and simulation in a stochastic framework such as stochastic discrete fracture network. Stochastic discrete fracture network models enable probabilistic assessment of flow, transport and geomechanical phenomena that are not adequately captured using continuum models. Despite the fundamental uncertainties inherited within the probabilistic reduction of the sparse data collected, very little work has been conducted on quantifying uncertainty on the reduced probabilistic distribution functions. In the current study, we investigate the impact of parameter uncertainties of the distribution functions that characterize discrete fracture networks on the flow, heat and mass transport and geomechanics. Numerical results of first, second and third moments, normalized to a base case scenario, are presented and compared to theoretical results extended from percolation theory. (Prepared by LLNL under Contract DE-AC52-07NA27344)

  12. A Public-Private Partnership Improves Clinical Performance In A Hospital Network In Lesotho.

    PubMed

    McIntosh, Nathalie; Grabowski, Aria; Jack, Brian; Nkabane-Nkholongo, Elizabeth Limakatso; Vian, Taryn

    2015-06-01

    Health care public-private partnerships (PPPs) between a government and the private sector are based on a business model that aims to leverage private-sector expertise to improve clinical performance in hospitals and other health facilities. Although the financial implications of such partnerships have been analyzed, few studies have examined the partnerships' impact on clinical performance outcomes. Using quantitative measures that reflected capacity, utilization, clinical quality, and patient outcomes, we compared a government-managed hospital network in Lesotho, Africa, and the new PPP-managed hospital network that replaced it. In addition, we used key informant interviews to help explain differences in performance. We found that the PPP-managed network delivered more and higher-quality services and achieved significant gains in clinical outcomes, compared to the government-managed network. We conclude that health care public-private partnerships may improve hospital performance in developing countries and that changes in management and leadership practices might account for differences in clinical outcomes.

  13. [Market and public policy network failures: challenges and possibilities for the Brazilian Unified Health System].

    PubMed

    Pinheiro Filho, Francisco Percival; Sarti, Flávia Mori

    2012-11-01

    The principles and guidelines of the Brazilian Unified Health System (SUS) impose a healthcare service structure based on public policy networks which, combined with the financing model adopted, leads to market failings. This imposes barriers to the management of the public health system and the enactment of SUS objectives. The institutional characteristics and the heterogeneity of players, allied to the existence of different healthcare approaches, generate analytical complexity in the study of the global dynamics of the SUS network. There are limitations in the use of quantitative methods based on static analysis of retrospective SUS data. Thus, an approach taking SUS as a complex system using innovative quantitative methodology based on computational simulation is proposed. This paper sought to analyze challenges and possibilities of the combined application of cellular automata modeling and agent-based modeling for simulation of the evolution of the SUS healthcare service network. This approach should permit better understanding of the organization, heterogeneity and structural dynamics of the SUS service network and a minimization of the effects of market failings on the Brazilian health system.

  14. Transport According to GARP: Receiving Retrograde Cargo at the Trans-Golgi Network

    PubMed Central

    Bonifacino, Juan S.; Hierro, Aitor

    2010-01-01

    Tethering factors are large protein complexes that capture transport vesicles and enable their fusion with acceptor organelles at different stages of the endomembrane system. Recent studies have shed new light on the structure and function of a heterotetrameric tethering factor named Golgi-associated retrograde protein (GARP), which promotes fusion of endosome-derived, retrograde transport carriers to the trans-Golgi network (TGN). X-ray crystallography of the Vps53 and Vps54 subunits of GARP has revealed that this complex is structurally related to other tethering factors such as the exocyst, COG and Dsl1, indicating that they all might work by a similar mechanism. Loss of GARP function compromises the growth, fertility and/or viability of the defective organisms, underscoring the essential nature of GARP-mediated retrograde transport. PMID:21183348

  15. Quantum transport in networks and photosynthetic complexes at the steady state.

    PubMed

    Manzano, Daniel

    2013-01-01

    Recently, several works have analysed the efficiency of photosynthetic complexes in a transient scenario and how that efficiency is affected by environmental noise. Here, following a quantum master equation approach, we study the energy and excitation transport in fully connected networks both in general and in the particular case of the Fenna-Matthew-Olson complex. The analysis is carried out for the steady state of the system where the excitation energy is constantly "flowing" through the system. Steady state transport scenarios are particularly relevant if the evolution of the quantum system is not conditioned on the arrival of individual excitations. By adding dephasing to the system, we analyse the possibility of noise-enhancement of the quantum transport.

  16. Transport according to GARP: receiving retrograde cargo at the trans-Golgi network.

    PubMed

    Bonifacino, Juan S; Hierro, Aitor

    2011-03-01

    Tethering factors are large protein complexes that capture transport vesicles and enable their fusion with acceptor organelles at different stages of the endomembrane system. Recent studies have shed new light on the structure and function of a heterotetrameric tethering factor named Golgi-associated retrograde protein (GARP), which promotes fusion of endosome-derived, retrograde transport carriers to the trans-Golgi network (TGN). X-ray crystallography of the Vps53 and Vps54 subunits of GARP has revealed that this complex is structurally related to other tethering factors such as the exocyst, the conserved oligomeric Golgi (COG) and Dsl1 (dependence on SLY1-20) complexes, indicating that they all might work by a similar mechanism. Loss of GARP function compromises the growth, fertility and/or viability of the defective organisms, emphasizing the essential nature of GARP-mediated retrograde transport.

  17. URBAN-NET: A Network-based Infrastructure Monitoring and Analysis System for Emergency Management and Public Safety

    SciTech Connect

    Lee, Sangkeun; Chen, Liangzhe; Duan, Sisi; Chinthavali, Supriya; Shankar, Mallikarjun; Prakash, B. Aditya

    2016-01-01

    Abstract Critical Infrastructures (CIs) such as energy, water, and transportation are complex networks that are crucial for sustaining day-to-day commodity flows vital to national security, economic stability, and public safety. The nature of these CIs is such that failures caused by an extreme weather event or a man-made incident can trigger widespread cascading failures, sending ripple effects at regional or even national scales. To minimize such effects, it is critical for emergency responders to identify existing or potential vulnerabilities within CIs during such stressor events in a systematic and quantifiable manner and take appropriate mitigating actions. We present here a novel critical infrastructure monitoring and analysis system named URBAN-NET. The system includes a software stack and tools for monitoring CIs, pre-processing data, interconnecting multiple CI datasets as a heterogeneous network, identifying vulnerabilities through graph-based topological analysis, and predicting consequences based on what-if simulations along with visualization. As a proof-of-concept, we present several case studies to show the capabilities of our system. We also discuss remaining challenges and future work.

  18. Public transit in America: Findings from the 1995 nationwide personal transportation survey

    SciTech Connect

    Polzin, S.E.; Rey, J.R.; Chu, X.

    1998-09-01

    The report has been prepared as an information base for people involved in planning, operating, marketing, and decision-making for public transit in America. The scale of analysis is limited to the 1995 NPTS, which includes a number of enhancements to the survey content and method and the resulting data base over previous surveys. The most notable enhancements include the addition of questions on public attitudes about transportation, the change from recollection to travel diary for trip recording, and the addition of characteristics for both residential and employment sites. The scale of analysis is also limited to describing various aspects of transit markets, rather than explaining the causality of various relationships observed. Statistics provided in this report complement those from other sources on transit at the national level, such as the decennial censuses from the US Bureau of the Census, the American Housing Survey from the Department of Housing and Urban Development, or the National Transit Data Base from the Federal Transit Administration.

  19. Totally asymmetric simple exclusion process simulations of molecular motor transport on random networks with asymmetric exit rates

    NASA Astrophysics Data System (ADS)

    Denisov, D. V.; Miedema, D. M.; Nienhuis, B.; Schall, P.

    2015-11-01

    Using the totally asymmetric simple-exclusion-process and mean-field transport theory, we investigate the transport in closed random networks with simple crossing topology—two incoming, two outgoing segments, as a model for molecular motor motion along biopolymer networks. Inspired by in vitro observation of molecular motor motion, we model the motor behavior at the intersections by introducing different exit rates for the two outgoing segments. Our simulations of this simple network reveal surprisingly rich behavior of the transport current with respect to the global density and exit rate ratio. For asymmetric exit rates, we find a broad current plateau at intermediate motor densities resulting from the competition of two subnetwork populations. This current plateau leads to stabilization of transport properties within such networks.

  20. Highly Scalable, UDP-Based Network Transport Protocols for Lambda Grids and 10 GE Routed Networks

    SciTech Connect

    PI: Robert Grossman Co-PI: Stephen Eick

    2009-08-04

    Summary of Report In work prior to this grant, NCDM developed a high performance data transport protocol called SABUL. During this grant, we refined SABUL’s functionality, and then extended both the capabilities and functionality and incorporated them into a new protocol called UDP-based Data transport Protocol, or UDT. We also began preliminary work on Composable UDT, a version of UDT that allows the user to choose among different congestion control algorithms and implement the algorithm of his choice at the time he compiles the code. Specifically, we: · Investigated the theoretical foundations of protocols similar to SABUL and UDT. · Performed design and development work of UDT, a protocol that uses UDP in both the data and control channels. · Began design and development work of Composable UDT, a protocol that supports the use of different congestion control algorithms by simply including the appropriate library when compiling the code. · Performed experimental studies using UDT and Composable UDT using real world applications such as the Sloan Digital Sky Survey (SDSS) astronomical data sets. · Released several versions of UDT and Composable, the most recent being v3.1.

  1. Unpacking complexity in public health interventions with the Actor-Network Theory.

    PubMed

    Bilodeau, Angèle; Potvin, Louise

    2016-08-04

    This article proposes a sociologically informed theoretical and methodological framework to address the complexity of public health interventions (PHI). It first proposes three arguments in favour of using the Actor-Network Theory (ANT) for the framework. ANT: (1) deals with systems made of human and non-human entities and proposes a relational view of action; (2) provides an understanding of the intervention-context interactions and (3) is a tool for opening the intervention's black box. Three principles derived from ANT addressing theoretical problems with conceptualisation of PHI as complex systems are proposed: (1) to focus on the process of connecting the network entities instead of their stabilised form; (2) both human and non-human entities composing networks have performative capacities and (3) network and intervention shape one another. Three methodological guidelines are further derived: (1) the researcher's task consists in documenting the events that transform the network and intervention; (2) events must be ordered chronologically to represent the intervention's evolution and (3) a broad range of data is needed to capture complex interventions' evolution. Using ANT as a guide, this paper helps reconcile technicist and social views of PHI and provides a mean to integrate process and effect studies of interventions.

  2. Effect of Internal Aperture Variability on Tracer Transport in Large Discrete Fracture Networks (DFN)

    NASA Astrophysics Data System (ADS)

    Makedonska, N.; Painter, S. L.; Hyman, J.; Karra, S.; Gable, C. W.; Viswanathan, H. S.

    2015-12-01

    Aperture variability within individual fractures is usually neglected in modeling flow and transport through fractured media. Typically, individual fractures are assumed to be homogeneous. However, in reality, individual fractures are heterogeneous, which may affect flow and transport in fractured media. The relative importance of including in-fracture variability in flow and transport modeling has been under debate for a long time. Previous studies have shown flow channeling on an individual fracture with internal variability, where the fracture is considered isolated from the rest of the fracture network. Although these studies yield some clear insights into the process, the boundary conditions are impractical for field-scale networks, where the realistic boundary conditions are determined by fracture connections in the network. Therefore, flow in a single fracture is controlled not only by in-fracture variability but also by boundary conditions. In order to address the question of the importance of in-fracture variability, the internal heterogeneity of every individual fracture is incorporated into a three-dimensional fracture network, represented by a composition of intersecting fractures. The new DFN simulation capability, dfnWorks, is used to generate a kilometer scale DFNs similar to the Forsmark, Sweden site. In our DFN model, the in-fracture aperture variability is scattered over each cell of the computational mesh along the fracture, representing by a stationary Gaussian random field with various correlation lengths. The Lagrangian particle tracking is conducted in multiple DFN realizations and the flow-dependent Lagrangian parameters, non-reacting travel time, τ, and cumulative reactivity parameter, β, are obtained along particles streamlines. It is shown that early particle travel times are more sensitive to in-fracture aperture variability than tails of travel time distributions, where no significant effect of the aperture variations and spatial

  3. 76 FR 42160 - Commercial Space Transportation Advisory Committee-Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-18

    ... Working Group of the Commercial Space Transportation Advisory Committee Teleconference. SUMMARY: Pursuant... is hereby given of a teleconference of the Space Transportation Operations Working Group (STOWG) of the Commercial Space Transportation Advisory Committee (COMSTAC). The teleconference will take...

  4. Influence of oxide particle network morphology on ion solvation and transport in "soggy sand" electrolytes.

    PubMed

    Das, Shyamal K; Bhattacharyya, Aninda J

    2010-05-27

    The role of oxide surface chemical composition and solvent on ion solvation and ion transport of "soggy sand" electrolytes are discussed here. A "soggy sand" electrolyte system comprising dispersions of hydrophilic/hydrophobic functionalized aerosil silica in lithium perchlorate-methoxy polyethylene glycol solution was employed for the study. Static and dynamic rheology measurements show formation of an attractive particle network in the case of the composite with unmodified aerosil silica (i.e., with surface silanol groups) as well as composites with hydrophobic alkane groups. While particle network in the composite with hydrophilic aerosil silica (unmodified) were due to hydrogen bonding, hydrophobic aerosil silica particles were held together via van der Waals forces. The network strength in the latter case (i.e., for hydrophobic composites) were weaker compared with the composite with unmodified aerosil silica. Both unmodified silica as well as hydrophobic silica composites displayed solid-like mechanical strength. No enhancement in ionic conductivity compared to the liquid electrolyte was observed in the case of the unmodified silica. This was attributed to the existence of a very strong particle network, which led to the "expulsion" of all conducting entities from the interfacial region between adjacent particles. The ionic conductivity for composites with hydrophobic aerosil particles displayed ionic conductivity dependent on the size of the hydrophobic chemical moiety. No spanning attractive particle network was observed for aerosil particles with surfaces modified with stronger hydrophilic groups (than silanol). The composite resembled a sol, and no percolation in ionic conductivity was observed.

  5. Plug in to the Utah Library Network, Reach Out to the World. Utah Library Network and Internet Training Handbook [for DOS]. Information Forum Publication #7.

    ERIC Educational Resources Information Center

    Reinwand, Louis; And Others

    This manual is designed to assist public libraries in Utah in their use of the Internet. Many of the examples used were created specifically to explain the use of products that the Utah Library Network provides for public libraries in Utah. The introduction provides background history and general information about the Internet and general…

  6. Pore network and pore scale modeling of reactive transport in porous media

    NASA Astrophysics Data System (ADS)

    Adler, P. M.; Vu, T. M.; Varloteaux, C.; Bekri, S.

    2012-12-01

    The study of the evolution of a porous medium where a reactive fluid flows is conditioned by the accurate determination of three macroscopic parameters governing the solute displacement, namely the solute velocity, dispersion and mean reaction rate. Of course, a possible application of such studies is CO2 sequestration. This presentation proposes to approach the determination of these parameters by two different ways and to compare them; both are on the pore scale. In the first one called PNM (for pore-network model), a pore-network is extracted from micro tomography images of a real porous medium. This network is composed of spherical pores joined by circular tubes; it is used to calculate transport macroscopic parameters and porosity-permeability evolution during the reactive transport flow as functions of dimensionless numbers representing the reaction and flow rate regimes. The flow is calculated by using Kirchhoff laws. Transport is determined in the asymptotic regime where the solute concentration undergoes an exponential evolution with time. In the second approach called PSM (for pore scale model), the pore-network model is used as a three dimensional medium which is discretized by the Level Set Method. The Stokes equations are solved in order to determine the local flow field and the corresponding permeability. The solute concentration is obtained by solving the local convection-diffusion equation in the 3D pore-network; numerical dispersion is reduced by a Flux Limiting Scheme. Two different geometries of porous media are addressed by both numerical codes. The first pore-network geometry is used to validate the PNM assumptions, whereas the second pore-network is defined for a better understanding of the dominant solute distribution. One of the main results obtained with the first pore-network is the dependence of the concentration profile on the Péclet number Pe in the pore-bodies. When this number increases, one has to switch from an assumption of

  7. Computational modeling of electrokinetic transport in random networks of micro-pores and nano-pores

    NASA Astrophysics Data System (ADS)

    Alizadeh, Shima; Mani, Ali

    2014-11-01

    A reduced order model has been developed to study the nonlinear electrokinetic behaviors emerging in the transport of ionic species through micro-scale and nano-scale porous media. In this approach a porous structure is modeled as a network of long and thin pores. By assuming transport equilibrium in the thin dimensions for each pore, a 1D transport equation is developed in the longitudinal direction covering a wide range of conditions including extreme limits of thick and thin electric double layers. This 1D model includes transport via diffusion, electromigration and wide range of advection mechanisms including pressure driven flow, electroosmosis, and diffusion osmosis. The area-averaged equations governing the axial transport from different pores are coupled at the pore intersections using the proper conservation laws. Moreover, an asymptotic treatment has been included in order to remove singularities in the limit of small concentration. The proposed method provides an efficient framework for insightful simulations of porous electrokinetic systems with applications in water desalination and energy storage. PhD student in Mechanical Engineering, Stanford University. She received her Master's degree in Mechanical Engineering from Stanford at 2013. Her research interests include CFD, high performance computing, and optimization.

  8. Regulation of plants' phosphate uptake in common mycorrhizal networks: Role of intraradical fungal phosphate transporters

    PubMed Central

    Walder, Florian; Boller, Thomas; Wiemken, Andres; Courty, Pierre-Emmanuel

    2016-01-01

    ABSTRACT We have recently identified two genes coding for inorganic phosphate transporters (Pht) in sorghum (Sorghum bicolor) and flax (Linum usitatissimum) that were induced in roots colonized by arbuscular mycorrhizal (AM) fungi. Mycorrhizal acquisition of inorganic phosphorus (Pi) was strongly affected by the combination of plant and AM fungal species, but the expression level of these genes coding for AM-inducible Pi transporters did not explain differences in plant phosphorus acquisition where flax and sorghum are sharing a common mycorrhizal network. In the present study, we investigated the possible role of fungal Pi transporters in the regulation of mycorrhizal Pi acquisition by measuring their expression in roots of flax and sorghum. One Pi transporter of Rhizophagus irregularis (RiPT5) showed a positive correlation with mycorrhizal Pi acquisition of sorghum. This indicates that a possible involvement in the regulation of mycorrhizal Pi acquisition. In general, expression of AMF Pi transporters was more related to mycorrhizal Pi acquisition of sorghum than of flax, indicating plant species-specific differences in the regulation of mycorrhizal Pi acquisition. PMID:26751110

  9. Allosteric transitions of the maltose transporter studied by an elastic network model.

    PubMed

    Li, Chun Hua; Yang, Yong Xiao; Su, Ji Guo; Liu, Bin; Tan, Jian Jun; Zhang, Xiao Yi; Wang, Cun Xin

    2014-07-01

    The maltose transporter from Escherichia coli is one of the ATP-binding cassette (ABC) transporters that utilize the energy from ATP hydrolysis to translocate substrates across cellular membranes. Until 2011, three crystal structures have been determined for maltose transporter at different states in the process of transportation. Here, based on these crystal structures, the allosteric pathway from the resting state (inward-facing) to the catalytic intermediate state (outward-facing) is studied by applying an adaptive anisotropic network model. The results suggest that the allosteric transitions proceed in a coupled way. The closing of the nucleotide-binding domains occurs first, and subsequently this conformational change is propagated to the transmembrane domains (TMD) via the EAA and EAS loops, and then to the maltose-binding protein, which facilitates the translocation of the maltose. It is also found that there exist nonrigid-body and asymmetric movements in the TMD. The cytoplasmic gate may only play the role of allosteric propagation during the transition from the pretranslocation to outward-facing states. In addition, the results show that the movment of the helical subdomain towards the RecA-like subdomain mainly occurs in the earlier stages of the transition. These results can provide some insights into the understanding of the mechanism of ABC transporters.

  10. 75 FR 38866 - Commercial Space Transportation Advisory Committee-Public Teleconference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-06

    ... given of a teleconference of the Space Transportation Operations Working Group (STOWG) of the Commercial Space Transportation Advisory Committee (COMSTAC). The teleconference will take place on Wednesday,...

  11. 75 FR 63534 - International Standards on the Transport of Dangerous Goods; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-15

    ... Agency (IAEA). Global harmonization of transport of dangerous goods regulations. Guiding principles for... enhance harmonization for international transport of hazardous materials. PHMSA has finalized a...

  12. Simulations of groundwater flow, transport, and age in Albuquerque, New Mexico, for a study of transport of anthropogenic and natural contaminants (TANC) to public-supply wells

    USGS Publications Warehouse

    Heywood, Charles E.

    2013-01-01

    Vulnerability to contamination from manmade and natural sources can be characterized by the groundwater-age distribution measured in a supply well and the associated implications for the source depths of the withdrawn water. Coupled groundwater flow and transport models were developed to simulate the transport of the geochemical age-tracers carbon-14, tritium, and three chlorofluorocarbon species to public-supply wells in Albuquerque, New Mexico. A separate, regional-scale simulation of transport of carbon-14 that used the flow-field computed by a previously documented regional groundwater flow model was calibrated and used to specify the initial concentrations of carbon-14 in the local-scale transport model. Observations of the concentrations of each of the five chemical species, in addition to water-level observations and measurements of intra-borehole flow within a public-supply well, were used to calibrate parameters of the local-scale groundwater flow and transport models. The calibrated groundwater flow model simulates the mixing of “young” groundwater, which entered the groundwater flow system after 1950 as recharge at the water table, with older resident groundwater that is more likely associated with natural contaminants. Complexity of the aquifer system in the zone of transport between the water table and public-supply well screens was simulated with a geostatistically generated stratigraphic realization based upon observed lithologic transitions at borehole control locations. Because effective porosity was simulated as spatially uniform, the simulated age tracers are more efficiently transported through the portions of the simulated aquifer with relatively higher simulated hydraulic conductivity. Non-pumping groundwater wells with long screens that connect aquifer intervals having different hydraulic heads can provide alternate pathways for contaminant transport that are faster than the advective transport through the aquifer material. Simulation of

  13. A new transport phenomenon in nanostructures: a mesoscopic analog of the Braess paradox encountered in road networks

    PubMed Central

    2012-01-01

    The Braess paradox, known for traffic and other classical networks, lies in the fact that adding a new route to a congested network in an attempt to relieve congestion can degrade counterintuitively the overall network performance. Recently, we have extended the concept of the Braess paradox to semiconductor mesoscopic networks, whose transport properties are governed by quantum physics. In this paper, we demonstrate theoretically that, alike in classical systems, congestion plays a key role in the occurrence of a Braess paradox in mesoscopic networks. PMID:22913510

  14. Publications

    Cancer.gov

    Information about NCI publications including PDQ cancer information for patients and health professionals, patient-education publications, fact sheets, dictionaries, NCI blogs and newsletters and major reports.

  15. M:N protection scheme and OADM implementation in WDM optical transport networks

    NASA Astrophysics Data System (ADS)

    Zong, Lei; Li, Yanhe; Zhang, Hanyi; Zheng, Xiaoping; Feng, Feifei; Guo, Yili

    2000-10-01

    In the presence of the increasing demand, it is urgent for the wavelength division multiplexing (WDM) optical transport network not only to boost the transmission capacity but also to enhance the survivability. In this paper, A M:N protection scheme for WDM optical transport networks is proposed and demonstrated. The M protection channels are used to transmit low priority traffic in normal condition, and can be switched automatically to replace a working channel when failure occurs to that working channel. Compared with the 1 + 1 protection system, the proposed scheme achieves better performance with lower costs. An optical add/drop multiplexer (OADM) is also proposed with the protection scheme. Any channel in M or in N can be dropped in the OADM according to the demand of the network management center. When failures occurred to a working channel that should be dropped in the OADM, and when the traffic on the failed working channel has already been switched to a protection channel at the previous node, the protection channel is dropped in the OADM automatically instead of the failed working channel. Then the corresponded adding signal is still added to the working channel, i.e., the protection channel is set free and can be used to carry low priority traffic again to the next node. Experimental result shows that the protection takes place within 7 ms, which satisfies the requirement of the ITU-T recommendations.

  16. The role of global trade and transport network topology in the human-mediated dispersal of alien species.

    PubMed

    Banks, Natalie Clare; Paini, Dean Ronald; Bayliss, Kirsty Louise; Hodda, Michael

    2015-02-01

    More people and goods are moving further and more frequently via many different trade and transport networks under current trends of globalisation. These networks can play a major role in the unintended introduction of exotic species to new locations. With the continuing rise in global trade, more research attention is being focused on the role of networks in the spread of invasive species. This represents an emerging field of research in invasion science and the substantial knowledge being generated within other disciplines can provide ecologists with new tools with which to study invasions. For the first time, we synthesise studies from several perspectives, approaches and disciplines to derive the fundamental characteristics of network topology determining the likelihood of spread of organisms via trade and transport networks. These characteristics can be used to identify critical points of vulnerability within these networks and enable the development of more effective strategies to prevent invasions.

  17. Commuter exposure to BTEX in public transportation modes in Bangkok, Thailand.

    PubMed

    Ongwandee, Maneerat; Chavalparit, Orathai

    2010-01-01

    Measurements and monitoring of volatile organic compounds (VOCs) have been conducted in the metropolitan Bangkok. However, in-vehicle levels of VOCs are still lacking. This study investigated VOCs concentrations in four public transportation modes in Bangkok, Thailand during two rush hour periods (7:00-9:00 a.m. and 4:00-7:00 p.m.). The four modes included an air-conditioned bus (A/C bus), non-air-conditioned bus (non-A/C bus), electric sky train, and a passenger boat traveling along the canal. Comparison among three important bus routes was also studied. In-vehicle air samples were collected using charcoal sorbent tubes and then analyzed by a gas chromatography-mass spectrometer. Results showed that the transportation modes significantly influenced the abundance of in-vehicle benzene, toluene, ethylbenzene, and m,p-xylene (BTEX). Median concentrations of BTEX were 11.7, 103, 11.7, and 42.8 microg/m3 in A/C bus; 37.1, 174, 14.7, and 55.4 microg/m3 in non-A/C bus; 2.0, 36.9, 0.5, and 0.5 Cig/m3 in sky train; and 3.1, 58.5, 0.5, and 6.2 microg/m3 in boat, respectively. Wilcoxon rank sum test indicated that toluene and m,p-xylene in the sky trains were statistically lower than that in the other three modes at a p-value of 0.05. There were statistical differences in TEX concentrations among the bus routes in the non-A/C buses. In addition, the benzene to toluene ratios implied that tail-pipe emissions were important contributor to the abundance of in-vehicle VOCs.

  18. Methods for analysis of passenger trip performance in a complex networked transportation system

    NASA Astrophysics Data System (ADS)

    Wang, Danyi

    2007-12-01

    The purpose of the Air Transportation System (ATS) is to provide safe and efficient transportation service of passengers and cargo. The on-time performance of a passenger's trip is a critical performance measurement of the Quality of Service (QOS) provided by any Air Transportation System. QOS has been correlated with airline profitability, productivity, customer loyalty and customer satisfaction (Heskett et al. 1994). Btatu and Barnhart have shown that official government and airline on-time performance metrics (i.e. flight-centric measures of air transportation) fail to accurately reflect the passenger experience (Btatu and Barnhart, 2005). Flight-based metrics do not include the trip delays accrued by passengers who were re-booked due to cancelled flights or missed connections. Also, flight-based metrics do not quantify the magnitude of the delay (only the likelihood) and thus fails to provide the consumer with a useful assessment of the impact of a delay. Passenger-centric metrics have not been developed because of the unavailability of airline proprietary data, which is also protected by anti-trust collusion concerns and civil liberty privacy restrictions. Moveover, the growth of the ATS is trending out of the historical range. The objectives of this research were to (1) estimate ATS-wide passenger trip delay using publicly accessible flight data, and (2) investigate passenger trip dynamics out of the range of historical data by building a passenger flow simulation model to predict impact on passenger trip time given anticipated changes in the future. The first objective enables researchers to conduct historical analysis on passenger on-time performance without proprietary itinerary data, and the second objective enables researchers to conduct experiments outside the range of historic data. The estimated passenger trip delay was for 1,030 routes between the 35 busiest airports in the United States in 2006. The major findings of this research are listed as

  19. Benefits on public health from transport-related greenhouse gas mitigation policies in Southeastern European cities.

    PubMed

    Sarigiannis, D A; Kontoroupis, P; Nikolaki, S; Gotti, A; Chapizanis, D; Karakitsios, S

    2017-02-01

    Climate change is a major environmental threat of our time. Cities have a significant impact on greenhouse gas emissions as most of the traffic, industry, commerce and more than 50% of world population is situated in urban areas. Southern Europe is a region that faces financial turmoil, enhanced migratory fluxes and climate change pressure. The case study of Thessaloniki is presented, one of the only two cities in Greece with established climate change action plans. The effects of feasible traffic policies in year 2020 are assessed and their potential health impact is compared to a business as usual scenario. Two types of measures are investigated: operation of underground rail in the city centre and changes in fleet composition. Potential co-benefits from reduced greenhouse gas emissions on public health by the year 2020 are computed utilizing state-of-the-art concentration response functions for PMx, NO2 and C6H6. Results show significant environmental health and monetary co-benefits when the city metro is coupled with appropriate changes in the traffic composition. Monetary savings due to avoided mortality or leukaemia incidence corresponding to the reduction in PM10, PM2.5, NO2 and C6H6 exposure will be 56.6, 45, 37.7 and 1.0 million Euros respectively. Promotion of 'green' transportation in the city (i.e. the wide use of electric vehicles), will provide monetary savings from the reduction in PM10, PM2.5, NO2 and C6H6 exposure up to 60.4, 49.1, 41.2 and 1.08 million Euros. Overall, it was shown that the respective GHG emission reduction policies resulted in clear co-benefits in terms of air quality improvement, public health protection and monetary loss mitigation.

  20. Role of water states on water uptake and proton transport in Nafion using molecular simulations and bimodal network

    SciTech Connect

    Hwang, Gi Suk; Kaviany, Massoud; Gostick, Jeffrey T.; Kientiz, Brian; Weber, Adam Z.; Kim, Moo Hwan

    2011-04-07

    In this paper, using molecular simulations and a bimodal-domain network, the role of water state on Nafion water uptake and water and proton transport is investigated. Although the smaller domains provide moderate transport pathways, their effectiveness remains low due to strong, resistive water molecules/domain surface interactions. Finally, the water occupancy of the larger domains yields bulk-like water, and causes the observed transition in the water uptake and significant increases in transport properties.