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Detalles de la revista
Formato
Revista
eISSN
1407-6179
Publicado por primera vez
20 Mar 2000
Periodo de publicación
4 veces al año
Idiomas
Inglés

Buscar

Volumen 19 (2018): Edición 2 (June 2018)

Detalles de la revista
Formato
Revista
eISSN
1407-6179
Publicado por primera vez
20 Mar 2000
Periodo de publicación
4 veces al año
Idiomas
Inglés

Buscar

7 Artículos
Acceso abierto

Simulation of Congestion Phenomena and Strategic Passenger Behaviour on Transit Networks

Publicado en línea: 28 Apr 2018
Páginas: 77 - 92

Resumen

Abstract

This article focuses on the simulation of transit networks, including passengers’ congestion phenomena and strategic behaviour, as a tool for planning and operation. Specifically, it describes a model of user equilibrium on large-scale transit networks considering on-board overcrowding, queuing at stops and dwelling delay, and representing in addition the effects of random events, such as the availability of seats and the waiting of vehicles, through hyperarcs. The assignment algorithm computes a strategy-based user equilibrium with implicit hyperpath enumeration by solving a fixed-point formulation, through a gradient projection method, which highly improves convergence performance. The model was implemented in .net as a dll that uses the software PTV Visum as I/O source. This article will focus on the model formulation and its capability of reproducing the target phenomena, while the results of model validation and testing will be described in a following paper.

Palabras clave

  • public transport assignment
  • hyperpaths
  • user equilibrium
  • failing probabilities
  • common lines
Acceso abierto

Real-Time System Based on Feature Extraction for Vehicle Detection and Classification

Publicado en línea: 28 Apr 2018
Páginas: 93 - 102

Resumen

Abstract

Today, Road traffic video surveillance becomes the centre of several concerns. It presents an important way for analysis of road traffic in highways. Road traffic video surveillance can help to resolve many problems which can influence road safety. This paper presents a real-time management and control system which serve to analyze road traffic using a stationary camera. The proposed system can measure the quantity and characteristics of traffic in real time based on three modules, segmentation, classification and vehicle counting. Our contribution consists of developing a feature-based counting system for vehicle detection and recognition under the conditions which present a challenge in recent systems, such as occlusions, and illumination conditions. Our method can perform vehicle detection and classification by eliminating the influence of many factors on system efficiency. The obtained results show that the system proposed in this paper provides a counting rate higher than that of some existing methods.

Palabras clave

  • Intelligent transportation systems
  • Vehicle detection
  • Occlusion handling
  • Vehicle classification
  • Background subtraction
  • Feature extraction
Acceso abierto

Evaluating Traffic Risk Indexes in Iran’s Rural Roads. Case Study: Ardabil-Meshkin Rural Road

Publicado en línea: 28 Apr 2018
Páginas: 103 - 112

Resumen

Abstract

The main objective of this study is to rank the chief parameters and their important features which lead to rural roads accidents in Iran. To conduct this, an item as Risk Index is defined as the risk of a parameter and feature causing road accidents. Of all detected parameters, only five parameters and their features were chosen. Then Analytic Hierarchy Process (AHP) was applied to find the scores of Risk Indexes of each parameter and feature to rank them with regard to the two main criteria. These criteria were “Effect on Accidents Number” and “Effect on Accident Severity”. The data of this research was collected from two forms of questionnaires. Each of the 622 participants of this research filled both forms of the questionnaires. The results show that considering only Risk Index of main parameters in rural roads led to a big misunderstanding about detecting traffic accident causes. A comparison between obtained scores for both Risk Indexes of parameters and features clarifies that paying more attention to road features rather than road parameters can bring about detecting hazardous locations more accurately to assign limited budget to vulnerable locations in rural roads and decrease the rate of traffic accidents.

Palabras clave

  • rural road
  • traffic accidents
  • road parameters
  • road features
Acceso abierto

Multi Criteria Evaluation Framework for Prioritizing Indian Railway Stations Using Modified Rough AHP-Mabac Method

Publicado en línea: 28 Apr 2018
Páginas: 113 - 127

Resumen

Abstract

This study proposes a hybrid multiple criteria decision making (MCDM) methodology for evaluating the performance of the Indian railway stations (IRS). Since the customers are heterogeneous and their requirements are often imprecise, the evaluation process is a critical step for prioritizing the IRS. To improve the existing approaches, an efficient evaluation technique has been proposed by integrating rough numbers, analytic hierarchy process (AHP) and multi-attribute border approximation area comparison (MABAC) methods in rough environment. The relative criteria weights based on their preferences given by experts is determined by rough AHP whereas evaluation of the alternatives based on these criteria are done by the modified rough MABAC method. A case study of prioritizing different railway stations in India is provided to demonstrate the efficiency and applicability of the proposed method. Among different criteria “proactively” is observed to be the most important criteria in our analysis, followed by ‘Railfanning’ and ‘DMO’ is found to be the best among the forty IRS in this study. Finally, a comparative analysis and validity testing of the proposed method are elaborated and the methodology provides a standard to select IRS on the basis of different criteria.

Palabras clave

  • Multiple criteria decision making
  • rough number
  • AHP
  • MABAC
  • Smart railway stations
Acceso abierto

Optimizing the Capacity of Cognitive Radio Networks with Power Control and Variable Spectrum Allocation

Publicado en línea: 28 Apr 2018
Páginas: 128 - 139

Resumen

Abstract

Cognitive Radio Networks (CRN) were introduced as a means to more efficiently reuse the licensed radio frequency spectrum. One of their salient features is the ability of unlicensed nodes to dynamically adapt their radio parameters according to their needs. This paper investigates the resource allocation problem in CRN by jointly considering power control and bandwidth for a set of secondary users (SU) transmitting simultaneously with a set of licensed users (PU), which transmissions must remain unaltered. The proposed allocation scheme is based on a Genetic Algorithm (GA) where the chromosome's genes represent the reconfigurable interface radio parameters, by defining genetic operations the GA is empowered to find a set of radio parameters that maximize the overall network capacity and under the physical interference model enforced to the transmissions of both PU’s and SU’s. The numerical results illustrate the prominent effect of adjusting jointly multiple radio parameters on the network capacity.

Palabras clave

  • cognitive radio networks
  • underlay mode
  • genetic algorithm
  • spectrum allocation
  • greedy algorithm
  • secondary users
  • shared spectrum
  • optimization problem
Acceso abierto

Effectiveness and Optimization of Harbour Tug Fleet

Publicado en línea: 28 Apr 2018
Páginas: 140 - 150

Resumen

Abstract

Determination of efficiency and optimization harbour tug fleet is based on simulation of fleet work and usage for this the methods of ship dynamics and probability theory. Visiting the port transport vessels of possible types is considered as random stream of given intensity. This stream is distributed over the berths. Productivities of berths are given random variables. Random variables are also characteristics of weather conditions in the harbour basin. Tug fleet is represented by the collection of existing port tugs of different types. Work of tugs is determined by operations of approaching to ships, escorting theirs in the near-port waters, posting on the approach channels, transportation within the port waters, berthing, unberthing and going out the ship from the port with the repetition of functioning operations in reverse order. Selection of tugs to service the next arriving or departing ship is dependent from the intensity of the current weather conditions in the port and busyness of tugs in operations with other ships. Work fleet is considered on the conditional time interval of one year. In this time the efficiency of the tug fleet is defined by economic indexes of fulfilment of all towing operations and operations on maintenance tugs. Optimization of the fleet composition is carried out according to the criteria required minimum total bollard pull, low cost and high profit. Based on performed research a program for calculating the efficiency and optimization of the port towing fleet is composed. The program can be adapted to any port with whatever types of tugs.

Palabras clave

  • simulation
  • optimization
  • harbour tug
  • software
  • port
Acceso abierto

Promising Directions for the Logistics Service Providers Development on the Russian Market in Times of Recession

Publicado en línea: 28 Apr 2018
Páginas: 151 - 163

Resumen

Abstract

The Russian market of logistics services suffered substantial losses during recent economic recession. Decrease in import from the EU and the USA, reduction of consumer spending within the country, increased borrowing costs led to sharp reduction in the growth rate of the investigated market value. Shortage of the modern infrastructure, fragmentation and imbalance of the Russian logistics market have contributed badly. This article focuses on identification of the promising strategic development directions for logistics service providers operating on the Russian market. On the basis of literature survey, the authors derive attractive client groups for 3PL operators, priority regions for geographical expansion as well as high-demand logistics and related services. The results of this survey could help logistics agents to define or clarify their market positioning and serve as a basis for further study of specific features in logistics outsourcing development in Russia.

Palabras clave

  • logistics service
  • logistics outsourcing
  • third party logistics
  • logistics infrastructure
7 Artículos
Acceso abierto

Simulation of Congestion Phenomena and Strategic Passenger Behaviour on Transit Networks

Publicado en línea: 28 Apr 2018
Páginas: 77 - 92

Resumen

Abstract

This article focuses on the simulation of transit networks, including passengers’ congestion phenomena and strategic behaviour, as a tool for planning and operation. Specifically, it describes a model of user equilibrium on large-scale transit networks considering on-board overcrowding, queuing at stops and dwelling delay, and representing in addition the effects of random events, such as the availability of seats and the waiting of vehicles, through hyperarcs. The assignment algorithm computes a strategy-based user equilibrium with implicit hyperpath enumeration by solving a fixed-point formulation, through a gradient projection method, which highly improves convergence performance. The model was implemented in .net as a dll that uses the software PTV Visum as I/O source. This article will focus on the model formulation and its capability of reproducing the target phenomena, while the results of model validation and testing will be described in a following paper.

Palabras clave

  • public transport assignment
  • hyperpaths
  • user equilibrium
  • failing probabilities
  • common lines
Acceso abierto

Real-Time System Based on Feature Extraction for Vehicle Detection and Classification

Publicado en línea: 28 Apr 2018
Páginas: 93 - 102

Resumen

Abstract

Today, Road traffic video surveillance becomes the centre of several concerns. It presents an important way for analysis of road traffic in highways. Road traffic video surveillance can help to resolve many problems which can influence road safety. This paper presents a real-time management and control system which serve to analyze road traffic using a stationary camera. The proposed system can measure the quantity and characteristics of traffic in real time based on three modules, segmentation, classification and vehicle counting. Our contribution consists of developing a feature-based counting system for vehicle detection and recognition under the conditions which present a challenge in recent systems, such as occlusions, and illumination conditions. Our method can perform vehicle detection and classification by eliminating the influence of many factors on system efficiency. The obtained results show that the system proposed in this paper provides a counting rate higher than that of some existing methods.

Palabras clave

  • Intelligent transportation systems
  • Vehicle detection
  • Occlusion handling
  • Vehicle classification
  • Background subtraction
  • Feature extraction
Acceso abierto

Evaluating Traffic Risk Indexes in Iran’s Rural Roads. Case Study: Ardabil-Meshkin Rural Road

Publicado en línea: 28 Apr 2018
Páginas: 103 - 112

Resumen

Abstract

The main objective of this study is to rank the chief parameters and their important features which lead to rural roads accidents in Iran. To conduct this, an item as Risk Index is defined as the risk of a parameter and feature causing road accidents. Of all detected parameters, only five parameters and their features were chosen. Then Analytic Hierarchy Process (AHP) was applied to find the scores of Risk Indexes of each parameter and feature to rank them with regard to the two main criteria. These criteria were “Effect on Accidents Number” and “Effect on Accident Severity”. The data of this research was collected from two forms of questionnaires. Each of the 622 participants of this research filled both forms of the questionnaires. The results show that considering only Risk Index of main parameters in rural roads led to a big misunderstanding about detecting traffic accident causes. A comparison between obtained scores for both Risk Indexes of parameters and features clarifies that paying more attention to road features rather than road parameters can bring about detecting hazardous locations more accurately to assign limited budget to vulnerable locations in rural roads and decrease the rate of traffic accidents.

Palabras clave

  • rural road
  • traffic accidents
  • road parameters
  • road features
Acceso abierto

Multi Criteria Evaluation Framework for Prioritizing Indian Railway Stations Using Modified Rough AHP-Mabac Method

Publicado en línea: 28 Apr 2018
Páginas: 113 - 127

Resumen

Abstract

This study proposes a hybrid multiple criteria decision making (MCDM) methodology for evaluating the performance of the Indian railway stations (IRS). Since the customers are heterogeneous and their requirements are often imprecise, the evaluation process is a critical step for prioritizing the IRS. To improve the existing approaches, an efficient evaluation technique has been proposed by integrating rough numbers, analytic hierarchy process (AHP) and multi-attribute border approximation area comparison (MABAC) methods in rough environment. The relative criteria weights based on their preferences given by experts is determined by rough AHP whereas evaluation of the alternatives based on these criteria are done by the modified rough MABAC method. A case study of prioritizing different railway stations in India is provided to demonstrate the efficiency and applicability of the proposed method. Among different criteria “proactively” is observed to be the most important criteria in our analysis, followed by ‘Railfanning’ and ‘DMO’ is found to be the best among the forty IRS in this study. Finally, a comparative analysis and validity testing of the proposed method are elaborated and the methodology provides a standard to select IRS on the basis of different criteria.

Palabras clave

  • Multiple criteria decision making
  • rough number
  • AHP
  • MABAC
  • Smart railway stations
Acceso abierto

Optimizing the Capacity of Cognitive Radio Networks with Power Control and Variable Spectrum Allocation

Publicado en línea: 28 Apr 2018
Páginas: 128 - 139

Resumen

Abstract

Cognitive Radio Networks (CRN) were introduced as a means to more efficiently reuse the licensed radio frequency spectrum. One of their salient features is the ability of unlicensed nodes to dynamically adapt their radio parameters according to their needs. This paper investigates the resource allocation problem in CRN by jointly considering power control and bandwidth for a set of secondary users (SU) transmitting simultaneously with a set of licensed users (PU), which transmissions must remain unaltered. The proposed allocation scheme is based on a Genetic Algorithm (GA) where the chromosome's genes represent the reconfigurable interface radio parameters, by defining genetic operations the GA is empowered to find a set of radio parameters that maximize the overall network capacity and under the physical interference model enforced to the transmissions of both PU’s and SU’s. The numerical results illustrate the prominent effect of adjusting jointly multiple radio parameters on the network capacity.

Palabras clave

  • cognitive radio networks
  • underlay mode
  • genetic algorithm
  • spectrum allocation
  • greedy algorithm
  • secondary users
  • shared spectrum
  • optimization problem
Acceso abierto

Effectiveness and Optimization of Harbour Tug Fleet

Publicado en línea: 28 Apr 2018
Páginas: 140 - 150

Resumen

Abstract

Determination of efficiency and optimization harbour tug fleet is based on simulation of fleet work and usage for this the methods of ship dynamics and probability theory. Visiting the port transport vessels of possible types is considered as random stream of given intensity. This stream is distributed over the berths. Productivities of berths are given random variables. Random variables are also characteristics of weather conditions in the harbour basin. Tug fleet is represented by the collection of existing port tugs of different types. Work of tugs is determined by operations of approaching to ships, escorting theirs in the near-port waters, posting on the approach channels, transportation within the port waters, berthing, unberthing and going out the ship from the port with the repetition of functioning operations in reverse order. Selection of tugs to service the next arriving or departing ship is dependent from the intensity of the current weather conditions in the port and busyness of tugs in operations with other ships. Work fleet is considered on the conditional time interval of one year. In this time the efficiency of the tug fleet is defined by economic indexes of fulfilment of all towing operations and operations on maintenance tugs. Optimization of the fleet composition is carried out according to the criteria required minimum total bollard pull, low cost and high profit. Based on performed research a program for calculating the efficiency and optimization of the port towing fleet is composed. The program can be adapted to any port with whatever types of tugs.

Palabras clave

  • simulation
  • optimization
  • harbour tug
  • software
  • port
Acceso abierto

Promising Directions for the Logistics Service Providers Development on the Russian Market in Times of Recession

Publicado en línea: 28 Apr 2018
Páginas: 151 - 163

Resumen

Abstract

The Russian market of logistics services suffered substantial losses during recent economic recession. Decrease in import from the EU and the USA, reduction of consumer spending within the country, increased borrowing costs led to sharp reduction in the growth rate of the investigated market value. Shortage of the modern infrastructure, fragmentation and imbalance of the Russian logistics market have contributed badly. This article focuses on identification of the promising strategic development directions for logistics service providers operating on the Russian market. On the basis of literature survey, the authors derive attractive client groups for 3PL operators, priority regions for geographical expansion as well as high-demand logistics and related services. The results of this survey could help logistics agents to define or clarify their market positioning and serve as a basis for further study of specific features in logistics outsourcing development in Russia.

Palabras clave

  • logistics service
  • logistics outsourcing
  • third party logistics
  • logistics infrastructure

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