The Experts below are selected from a list of 9651 Experts worldwide ranked by ideXlab platform

Manyapetsa, Kgomotso Peter - One of the best experts on this subject based on the ideXlab platform.

  • Trade-off study of a new build versus upgraded existing undersea optic fibre cable system
    2015
    Co-Authors: Manyapetsa, Kgomotso Peter
    Abstract:

    Abstract: Undersea optic fibre cable systems are an integral part of the international telecommunications infrastructure for supporting growing marketplace bandwidth needs and they have become a critical component to the constantly evolving Internet traffic content. The issue associated with existing undersea optic fibre cable systems is the scalability of the capacity in meeting and anticipating future capacity demands of the network. In order to meet increased traffic demands, telecoms companies are required to build new systems or upgrade the existing ones in order to address this issue of increased capacity demand. Building an undersea optic fibre cable system is an expensive venture, so much so that the system owners are reluctant to invest in newer optic fibre cable system whilst they have ownership on existing systems. They seek ways in which to optimise the existing system in order to extend the economic lifespan of the system. The research sought to demonstrate how effective it is to upgrade the existing undersea optic fibre cable systems given the technological advancements, expenditures as opposed to constructing a new undersea optic fibre cable system through a trade-off study of a new build versus upgraded existing undersea optic fibre cable system activities. It was found that upgrading an existing system to a capacity beyond the original design capacity was achievable through the enablers such as Wavelength Division Multiplex, spectral efficiency, coherent detection, modulation formats and forward error correction techniques. It was found that only the Terminal Station equipment gets altered whilst the submerged plant remains unchanged, making it possible to optimise the capacity on the existing undersea optic fibre system effectively in a timeous period and enable the exploitation of the increased traffic demand. Whereas to construct a new optic fibre cable system requires huge capital investments and time to implement the system can take a minimum of 24 months without delays, however delays are part and parcel of system construction, delays ranging from obtaining permits, equipment/material delivery, construction of both the submerged and dry plants.M.Ing. (Engineering Management

  • Trade-off study of a new build versus upgraded existing undersea optic fibre cable system
    2015
    Co-Authors: Manyapetsa, Kgomotso Peter
    Abstract:

    Abstract: Undersea optic fibre cable systems are an integral part of the international telecommunications infrastructure for supporting growing marketplace bandwidth needs and they have become a critical component to the constantly evolving Internet traffic content. The issue associated with existing undersea optic fibre cable systems is the scalability of the capacity in meeting and anticipating future capacity demands of the network. In order to meet increased traffic demands, telecoms companies are required to build new systems or upgrade the existing ones in order to address this issue of increased capacity demand. Building an undersea optic fibre cable system is an expensive venture, so much so that the system owners are reluctant to invest in newer optic fibre cable system whilst they have ownership on existing systems. They seek ways in which to optimise the existing system in order to extend the economic lifespan of the system. The research sought to demonstrate how effective it is to upgrade the existing undersea optic fibre cable systems given the technological advancements, expenditures as opposed to constructing a new undersea optic fibre cable system through a trade-off study of a new build versus upgraded existing undersea optic fibre cable system activities. It was found that upgrading an existing system to a capacity beyond the original design capacity was achievable through the enablers such as Wavelength Division Multiplex, spectral efficiency, coherent detection, modulation formats and forward error correction techniques. It was found that only the Terminal Station equipment gets altered whilst the submerged plant remains unchanged, making it possible to optimise the capacity on the existing undersea optic fibre system effectively in a timeous period and enable the exploitation of the increased traffic demand. Whereas to construct a new optic fibre cable system requires huge capital investments and time to implement the system can take a minimum of 24 months without delays, however delays are part and parcel of system construction, delays ranging from obtaining permits, equipment/material delivery, construction of both the submerged and dry plants.M.Eng. (Engineering Management

Dario Pacciarelli - One of the best experts on this subject based on the ideXlab platform.

  • ant colony optimization for the real time train routing selection problem
    Transportation Research Part B-methodological, 2016
    Co-Authors: Marcella Sama, Paola Pellegrini, Andrea Dariano, Joaquin Rodriguez, Dario Pacciarelli
    Abstract:

    This paper deals with the real-time problem of scheduling and routing trains in a railway network. In the related literature, this problem is usually solved starting from a subset of routing alternatives and computing the near-optimal solution of the simplified routing problem. We study how to select the best subset of routing alternatives for each train among all possible alternatives. The real-time train routing selection problem is formulated as an integer linear programming formulation and solved via an algorithm inspired by the ant colonies’ behavior. The real-time railway traffic management problem takes as input the best subset of routing alternatives and is solved as a mixed-integer linear program. The proposed methodology is tested on two practical case studies of the French railway infrastructure: the Lille Terminal Station area and the Rouen line. The computational experiments are based on several practical disturbed scenarios. Our methodology allows the improvement of the state of the art in terms of the minimization of train consecutive delays. The improvement is around 22% for the Rouen instances and around 56% for the Lille instances.

Weijea Chang - One of the best experts on this subject based on the ideXlab platform.

  • design of real time fuzzy bus holding system for the mass rapid transit transfer system
    Expert Systems With Applications, 2012
    Co-Authors: Weijea Chang
    Abstract:

    In this research, we aim to design real-time fuzzy bus holding system (FBHS) for the mass rapid transit (MRT) transfer system with real-time information for a Terminal Station with in a metropolitan area. We employ fuzzy logic to develop a model for the MRT-bus system to achieve the following goals pertaining to bus holding strategies used: to reduce the bus waiting time, to reduce the passenger waiting time, and to reduce passenger traveling time. In order to enhance the performance of the MRT-bus transfer system, we develop several fuzzy rules in the transfer models that are different functions of the travel time taken by buses during different time periods, such as rush hours and off-peak hours. Real-time traffic information acquired by the intelligent transportation systems through global positioning systems is used as input data for the FBHS. A performance index function is derived and served as the performance measure to compare our system with real data. The experimental results show that the FBHS significantly reduces the overall passenger waiting time and improves the performance of the MRT-bus transfer system.

Marcella Sama - One of the best experts on this subject based on the ideXlab platform.

  • ant colony optimization for the real time train routing selection problem
    Transportation Research Part B-methodological, 2016
    Co-Authors: Marcella Sama, Paola Pellegrini, Andrea Dariano, Joaquin Rodriguez, Dario Pacciarelli
    Abstract:

    This paper deals with the real-time problem of scheduling and routing trains in a railway network. In the related literature, this problem is usually solved starting from a subset of routing alternatives and computing the near-optimal solution of the simplified routing problem. We study how to select the best subset of routing alternatives for each train among all possible alternatives. The real-time train routing selection problem is formulated as an integer linear programming formulation and solved via an algorithm inspired by the ant colonies’ behavior. The real-time railway traffic management problem takes as input the best subset of routing alternatives and is solved as a mixed-integer linear program. The proposed methodology is tested on two practical case studies of the French railway infrastructure: the Lille Terminal Station area and the Rouen line. The computational experiments are based on several practical disturbed scenarios. Our methodology allows the improvement of the state of the art in terms of the minimization of train consecutive delays. The improvement is around 22% for the Rouen instances and around 56% for the Lille instances.

Huisman Dennis - One of the best experts on this subject based on the ideXlab platform.

  • A self-organizing policy for vehicle dispatching in public transit systems with multiple lines
    'Elsevier BV', 2021
    Co-Authors: Van Lieshout, Rolf N., Bouman, Paul C., Van Den Akker Marjan, Huisman Dennis
    Abstract:

    In this paper, we propose and analyze an online, decentralized policy for dispatching vehicles in a multi-line public transit system. In the policy, vehicles arriving at a Terminal Station are assigned to the lines starting at the Station in a round-robin fashion. Departure times are selected to minimize deviations from a certain target headway. We prove that this policy is self-organizing: given that there is a sufficient number of available vehicles, a timetable spontaneously emerges that meets the target headway of every line. Moreover, in case one of the vehicles breaks down, the remaining vehicles automatically redistribute over the network to re-establish such a timetable. We present both theoretical and numerical results on the time until a stable state is reached and on how quickly the system recovers after the breakdown of a vehicle. Experiments on three real-world transit systems show that our policy performs well, even if not all assumptions required for the theoretical analysis are met: if there are enough vehicles, the realized headways are typically close to the target headways. These promising results suggest that our self-organizing policy could be useful in situations where centralized dispatching is impractical or simply impossible due to an abundance of disruptions or the absence of information systems