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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 16 (2015): Edición 3 (September 2015)

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

Early 2015 Performance In Baltic Sea Ports: Forecasts Of Estonian Performance For Entire Year

Publicado en línea: 22 Jun 2015
Páginas: 183 - 189

Resumen

Abstract

Many changes have appeared in year 2015. In Europe economic malaise has continued since debt crisis started in year 2010, and although its effects on Northern Europe have started to diminish, new economic dark clouds have appeared through sanctions set by both European Union and Russia to each other during year 2014. Together with these, shipping sector has been under pressure due to strict sulphur regulation implemented from early 2015 onwards in the entire Baltic Sea Region. Due to these factors, sea ports at Baltic Sea have been under pressure during the first months of 2015, this particularly concerning container handling. Based on our regression model forecast, Estonia and Port of Tallinn shall have clearly declining container handling year ahead. However, overall handling at sea port is not so easy to forecast.

Palabras clave

  • Baltic Sea
  • crisis
  • sea ports
  • handling
  • TEU
Acceso abierto

Mixed Vehicle Flow At Signalized Intersection: Markov Chain Analysis

Publicado en línea: 22 Jun 2015
Páginas: 190 - 196

Resumen

Abstract

We assume that a Poisson flow of vehicles arrives at isolated signalized intersection, and each vehicle, independently of others, represents a random number X of passenger car units (PCU’s). We analyze numerically the stationary distribution of the queue process {Zn}, where Zn is the number of PCU’s in a queue at the beginning of the n-th red phase, n. We approximate the number Yn of PCU’s arriving during one red-green cycle by a two-parameter Negative Binomial Distribution (NBD). The well-known fact is that {Zn} follow an infinite-state Markov chain. We approximate its stationary distribution using a finite-state Markov chain. We show numerically that there is a strong dependence of the mean queue length E[Zn] in equilibrium on the input distribution of Yn and, in particular, on the ”over dispersion” parameter γ= Var[Yn]/E[Yn]. For Poisson input, γ = 1. γ > 1 indicates presence of heavy-tailed input. In reality it means that a relatively large ”portion” of PCU’s, considerably exceeding the average, may arrive with high probability during one red-green cycle. Empirical formulas are presented for an accurate estimation of mean queue length as a function of load and g of the input flow. Using the Markov chain technique, we analyze the mean ”virtual” delay time for a car which always arrives at the beginning of the red phase.

Palabras clave

  • signalized traffic light
  • Markov chain
  • average queue length
  • mixed vehicle input flow
  • negative binomial distribution
  • over dispersed input
  • virtual delay
Acceso abierto

Users’ Perception And Reported Effects Of Long-term Access To In-Vehicle Traffic Information Services Mediated Through Nomadic Devices

Publicado en línea: 22 Jun 2015
Páginas: 197 - 206

Resumen

Abstract

ICT-mediated traffic information has been argued to contribute to a more sustainable transport system through affecting drivers. Nevertheless, long-term effects of travellers having access to nomadic in-vehicle systems for traveller information are not well known. This study presents the results from a multi-national large-scale field operational test (FOT). The results show that the users in general were positive to the tested systems and that there were several effects on their driving behaviour but in many cases the effects were limited. Moreover the effects varied between system types. Positive effects were related to comfort, as well as individual and system efficiency. One could also notice that perceived effects were not as high as the participants had expected, leading to some disappointment. Most of the times this was due to the tested systems functioning in a less than optimal way.

Palabras clave

  • field operational test
  • traffic information
  • nomadic device
Acceso abierto

Formal And Informal Macro-Regional Transport Clusters As A Primary Step In The Design And Implementation Of Cluster-Based Strategies

Publicado en línea: 22 Jun 2015
Páginas: 207 - 216

Resumen

Abstract

The aim of the study is the identification of a formal macro-regional transport and logistics cluster and its development trends on a macro-regional level in 2007-2011 by means of the hierarchical cluster analysis. The central approach of the study is based on two concepts: 1) the concept of formal and informal macro-regions, and 2) the concept of clustering which is based on the similarities shared by the countries of a macro-region and tightly related to the concept of macro-region. The authors seek to answer the question whether the formation of a formal transport cluster could provide the BSR a stable competitive position in the global transportation and logistics market.

Palabras clave

  • Baltic Sea Region (BSR)
  • hierarchical cluster analysis (statistics)
  • location quotient
  • macro-region
  • transport and logistics
Acceso abierto

Employment Of IGBT-Transistors For Bipolar Impulsed Micro-Arc Oxidation

Publicado en línea: 22 Jun 2015
Páginas: 217 - 223

Resumen

Abstract

The paper is devoted to the use of insulated gate bipolar transistors (IGBT) for the micro-arc oxidation (MAO) process. The technical requirements to the current switches of power supplies for the pulsed bipolar MAO technology have been developed. The research installation for investigating the IGBT commutation processes during the pulse anode-cathode oxidation has been constructed. The experiments have been performed with its help in order to estimate the possibility of using half-bridge IGBT-modules with different drivers. The research results of the commutation processes investigation for different IGBT half- bridge modules are presented.

Palabras clave

  • micro-arc oxidation
  • insulated gate bipolar transistors
  • high voltage
  • commutation process
  • ballast resistance
Acceso abierto

New Solutions Based On Wireless Networks For Dynamic Traffic Lights Management: A Comparison Between IEEE 802.15.4 And Bluetooth

Publicado en línea: 22 Jun 2015
Páginas: 224 - 236

Resumen

Abstract

The Wireless Sensor Networks are widely used to detect and exchange information and in recent years they have been increasingly involved in Intelligent Transportation System applications, especially in dynamic management of signalized intersections. In fact, the real-time knowledge of information concerning traffic light junctions represents a valid solution to congestion problems. In this paper, a wireless network architecture, based on IEEE 802.15.4 or Bluetooth, in order to monitor vehicular traffic flows near to traffic lights, is introduced. Moreover, an innovative algorithm is proposed in order to determine dynamically green times and phase sequence of traffic lights, based on measured values of traffic flows. Several simulations compare IEEE 802.15.4 and Bluetooth protocols in order to identify the more suitable communication protocol for ITS applications. Furthermore, in order to confirm the validity of the proposed algorithm for the dynamic management of traffic lights, some case studies have been considered and several simulations have been performed.

Palabras clave

  • wireless sensor networks
  • road monitoring
  • traffic lights
  • intelligent transportation systems
Acceso abierto

The Variant Approach To The Optimization Of The Postal Transportation Network In The Conditions Of The Slovak Republic

Publicado en línea: 22 Jun 2015
Páginas: 237 - 245

Resumen

Abstract

The optimizing process of the postal transportation network can be based on several variables and on different infrastructures. The most commonly used variables for optimization are time and distance. This article is focused on the comparison of the results of the optimization process based on the time and distance variables in the conditions of the Slovak national postal operator.

The different types of the underlying infrastructures (roads or railways) could be used for optimization based on the territory conditions. For the optimization, there has been used the p-median method, that describes the problem of locating P “facilities” relative to a set of “customers” in such a way that the sum of the shortest demand weighted distance between “customers” and “facilities” is minimized.

In the conclusion, the article authors will formulate the rule for selection of the best optimization variables for the postal transportation network optimization.

Palabras clave

  • optimization
  • postal transportation network
  • distance
  • time
  • infrastructure
  • p-median
7 Artículos
Acceso abierto

Early 2015 Performance In Baltic Sea Ports: Forecasts Of Estonian Performance For Entire Year

Publicado en línea: 22 Jun 2015
Páginas: 183 - 189

Resumen

Abstract

Many changes have appeared in year 2015. In Europe economic malaise has continued since debt crisis started in year 2010, and although its effects on Northern Europe have started to diminish, new economic dark clouds have appeared through sanctions set by both European Union and Russia to each other during year 2014. Together with these, shipping sector has been under pressure due to strict sulphur regulation implemented from early 2015 onwards in the entire Baltic Sea Region. Due to these factors, sea ports at Baltic Sea have been under pressure during the first months of 2015, this particularly concerning container handling. Based on our regression model forecast, Estonia and Port of Tallinn shall have clearly declining container handling year ahead. However, overall handling at sea port is not so easy to forecast.

Palabras clave

  • Baltic Sea
  • crisis
  • sea ports
  • handling
  • TEU
Acceso abierto

Mixed Vehicle Flow At Signalized Intersection: Markov Chain Analysis

Publicado en línea: 22 Jun 2015
Páginas: 190 - 196

Resumen

Abstract

We assume that a Poisson flow of vehicles arrives at isolated signalized intersection, and each vehicle, independently of others, represents a random number X of passenger car units (PCU’s). We analyze numerically the stationary distribution of the queue process {Zn}, where Zn is the number of PCU’s in a queue at the beginning of the n-th red phase, n. We approximate the number Yn of PCU’s arriving during one red-green cycle by a two-parameter Negative Binomial Distribution (NBD). The well-known fact is that {Zn} follow an infinite-state Markov chain. We approximate its stationary distribution using a finite-state Markov chain. We show numerically that there is a strong dependence of the mean queue length E[Zn] in equilibrium on the input distribution of Yn and, in particular, on the ”over dispersion” parameter γ= Var[Yn]/E[Yn]. For Poisson input, γ = 1. γ > 1 indicates presence of heavy-tailed input. In reality it means that a relatively large ”portion” of PCU’s, considerably exceeding the average, may arrive with high probability during one red-green cycle. Empirical formulas are presented for an accurate estimation of mean queue length as a function of load and g of the input flow. Using the Markov chain technique, we analyze the mean ”virtual” delay time for a car which always arrives at the beginning of the red phase.

Palabras clave

  • signalized traffic light
  • Markov chain
  • average queue length
  • mixed vehicle input flow
  • negative binomial distribution
  • over dispersed input
  • virtual delay
Acceso abierto

Users’ Perception And Reported Effects Of Long-term Access To In-Vehicle Traffic Information Services Mediated Through Nomadic Devices

Publicado en línea: 22 Jun 2015
Páginas: 197 - 206

Resumen

Abstract

ICT-mediated traffic information has been argued to contribute to a more sustainable transport system through affecting drivers. Nevertheless, long-term effects of travellers having access to nomadic in-vehicle systems for traveller information are not well known. This study presents the results from a multi-national large-scale field operational test (FOT). The results show that the users in general were positive to the tested systems and that there were several effects on their driving behaviour but in many cases the effects were limited. Moreover the effects varied between system types. Positive effects were related to comfort, as well as individual and system efficiency. One could also notice that perceived effects were not as high as the participants had expected, leading to some disappointment. Most of the times this was due to the tested systems functioning in a less than optimal way.

Palabras clave

  • field operational test
  • traffic information
  • nomadic device
Acceso abierto

Formal And Informal Macro-Regional Transport Clusters As A Primary Step In The Design And Implementation Of Cluster-Based Strategies

Publicado en línea: 22 Jun 2015
Páginas: 207 - 216

Resumen

Abstract

The aim of the study is the identification of a formal macro-regional transport and logistics cluster and its development trends on a macro-regional level in 2007-2011 by means of the hierarchical cluster analysis. The central approach of the study is based on two concepts: 1) the concept of formal and informal macro-regions, and 2) the concept of clustering which is based on the similarities shared by the countries of a macro-region and tightly related to the concept of macro-region. The authors seek to answer the question whether the formation of a formal transport cluster could provide the BSR a stable competitive position in the global transportation and logistics market.

Palabras clave

  • Baltic Sea Region (BSR)
  • hierarchical cluster analysis (statistics)
  • location quotient
  • macro-region
  • transport and logistics
Acceso abierto

Employment Of IGBT-Transistors For Bipolar Impulsed Micro-Arc Oxidation

Publicado en línea: 22 Jun 2015
Páginas: 217 - 223

Resumen

Abstract

The paper is devoted to the use of insulated gate bipolar transistors (IGBT) for the micro-arc oxidation (MAO) process. The technical requirements to the current switches of power supplies for the pulsed bipolar MAO technology have been developed. The research installation for investigating the IGBT commutation processes during the pulse anode-cathode oxidation has been constructed. The experiments have been performed with its help in order to estimate the possibility of using half-bridge IGBT-modules with different drivers. The research results of the commutation processes investigation for different IGBT half- bridge modules are presented.

Palabras clave

  • micro-arc oxidation
  • insulated gate bipolar transistors
  • high voltage
  • commutation process
  • ballast resistance
Acceso abierto

New Solutions Based On Wireless Networks For Dynamic Traffic Lights Management: A Comparison Between IEEE 802.15.4 And Bluetooth

Publicado en línea: 22 Jun 2015
Páginas: 224 - 236

Resumen

Abstract

The Wireless Sensor Networks are widely used to detect and exchange information and in recent years they have been increasingly involved in Intelligent Transportation System applications, especially in dynamic management of signalized intersections. In fact, the real-time knowledge of information concerning traffic light junctions represents a valid solution to congestion problems. In this paper, a wireless network architecture, based on IEEE 802.15.4 or Bluetooth, in order to monitor vehicular traffic flows near to traffic lights, is introduced. Moreover, an innovative algorithm is proposed in order to determine dynamically green times and phase sequence of traffic lights, based on measured values of traffic flows. Several simulations compare IEEE 802.15.4 and Bluetooth protocols in order to identify the more suitable communication protocol for ITS applications. Furthermore, in order to confirm the validity of the proposed algorithm for the dynamic management of traffic lights, some case studies have been considered and several simulations have been performed.

Palabras clave

  • wireless sensor networks
  • road monitoring
  • traffic lights
  • intelligent transportation systems
Acceso abierto

The Variant Approach To The Optimization Of The Postal Transportation Network In The Conditions Of The Slovak Republic

Publicado en línea: 22 Jun 2015
Páginas: 237 - 245

Resumen

Abstract

The optimizing process of the postal transportation network can be based on several variables and on different infrastructures. The most commonly used variables for optimization are time and distance. This article is focused on the comparison of the results of the optimization process based on the time and distance variables in the conditions of the Slovak national postal operator.

The different types of the underlying infrastructures (roads or railways) could be used for optimization based on the territory conditions. For the optimization, there has been used the p-median method, that describes the problem of locating P “facilities” relative to a set of “customers” in such a way that the sum of the shortest demand weighted distance between “customers” and “facilities” is minimized.

In the conclusion, the article authors will formulate the rule for selection of the best optimization variables for the postal transportation network optimization.

Palabras clave

  • optimization
  • postal transportation network
  • distance
  • time
  • infrastructure
  • p-median

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