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Journal Details
Format
Journal
eISSN
1407-6179
First Published
20 Mar 2000
Publication timeframe
4 times per year
Languages
English

Search

Volume 17 (2016): Issue 3 (September 2016)

Journal Details
Format
Journal
eISSN
1407-6179
First Published
20 Mar 2000
Publication timeframe
4 times per year
Languages
English

Search

7 Articles
Open Access

Performance Availability Assessment of Combined Multi Power Source Traction Drive Considering Real Operational Conditions

Published Online: 28 Jun 2016
Page range: 179 - 191

Abstract

Abststract

The present paper deals with the vehicle’s traction electric drive, consisting of several various electric power sources. One of the main requirements for such systems are the safety and sustainable operations, achieved largely the implementation of an uninterrupted supply of the vehicle’s propulsion system with an electric power.

One way of realization of the required level of operational sustainability is usage of Multi Power Source Traction Drive. This type of vehicle’s propulsion systems is widely applied on the ships, trains, planes, heavy trucks. The most important impact on the sustainability of functioning of the ship’s propulsion system have operational conditions, especially for the cargo ship, operating in Arctic region.

This paper presents the application of the LZ-transform method to assessing the important parameter of the vehicle’s operational sustainability - availability of the multi-state (MSS) Multi Power Source Traction Drive, which includes Diesel-Generators and Gas-Turbine-Generators considering the impact of the real operating conditions.

Straightforward Markov method applied to solve this problem will require building of a system’s model with numerous numbers of states and solve a corresponding system of multiple differential equations. LZ-transform method, drastically simplified the solution.

Keywords

  • Multi Power Source Traction Drive
  • LZ-transform method
  • Multi-state systems
  • Assessing Operational Sustainability
  • Arctic cargo ship
  • Electric Propulsion System
Open Access

OFDM Signal Research with Varied Subcarriers Number

Published Online: 28 Jun 2016
Page range: 192 - 201

Abstract

Abstract

The orthogonal frequency division multiplexing (OFDM) aggregate signal energy characteristics are studied based on the OFDM signal simulation model. The information reliability of OFDM signal is explored for different sets of OFDM subcarrier numbers and varied multiposition keying types (MPK) on OFDM subcarriers. The conditions for optimal gain factor for OFDM signal are described analytically based on the simulation modeling results. The effect and value from using an optimal gain factor for OFDM signal is shown in this paper.

Keywords

  • OFDM
  • simulation
  • subcarriers number
  • multiposition keying
  • BER
  • optimal gain factor
Open Access

Use of Information Intelligent Components for the Analysis of Complex Processes of Marine Energy Systems

Published Online: 28 Jun 2016
Page range: 202 - 211

Abstract

Abstract

Synchronous motors and their modifications (ac converter-fed motor, etc.) enable to develop low-noise, reliable and economically efficient electric drive systems. The construction of up-to-date systems based on the synchronous machines is impossible without development of the computing software incorporating mathematical and computing simulation. In its turn, modelling of the synchronous machines as a rule is based on the equations by Park-Gorev, application of which requires adoption of a series of allowances. These allowances in a number of cases do not permit to obtain adequate results of the simulation coinciding with the results of field experiments of the systems under review. Moreover, while applying the system of equations by Park-Gorev to research the systems including interaction of synchronous machines with semiconducting converters of electric energy it is necessary simulate the process of formation their controlling signals in the sphere of frequency. If the states of converter’s keys are defined not only by controlling impulses but also by the state of currents in the synchronous machines flowing through them, such approach is not reasonable.

Keywords

  • power systems
  • intellectual systems
  • synchronous machines
  • ship
  • simulation
Open Access

Competitive Traffic Assignment in Road Networks

Published Online: 28 Jun 2016
Page range: 212 - 221

Abstract

Abstract

Recently in-vehicle route guidance and information systems are rapidly developing. Such systems are expected to reduce congestion in an urban traffic area. This social benefit is believed to be reached by imposing the route choices on the network users that lead to the system optimum traffic assignment. However, guidance service could be offered by different competitive business companies. Then route choices of different mutually independent groups of users may reject traffic assignment from the system optimum state. In this paper, a game theoretic approach is shown to be very efficient to formalize competitive traffic assignment problem with various groups of users in the form of non-cooperative network game with the Nash equilibrium search. The relationships between the Wardrop’s system optimum associated with the traffic assignment problem and the Nash equilibrium associated with the competitive traffic assignment problem are investigated. Moreover, some related aspects of the Nash equilibrium and the Wardrop’s user equilibrium assignments are also discussed.

Keywords

  • competitive traffic assignment
  • Nash equilibrium
  • system optimum of Wardrop
  • user equilibrium of Wardrop
Open Access

Multiple Approaches of Solving Allocation Problems on Postal Transportation Network in Conditions of Large Countries

Published Online: 28 Jun 2016
Page range: 222 - 230

Abstract

Abstract

The article deals with the optimizing the postal transportation network with two different optimizing methods. The research adopted in this article uses allocation models within graph theory to obtain results for addressed optimization problem. The article presents and compares two types of these models: p-median and uncapacitated fixed charge facility location model. The aim of p-median model is to find the location of P facilities in network, serving all demands in a way ensuring the average transport cost to be minimal. Fixed charge location model approach the issue of facility location based on minimizing the overall costs of implementation of selected variants. The latter this two models are subsequently applied on the postal network to determine the optimal location of postal facilities. These two models are adopted in the condition of large country with area above 300 000 km2. The Italy was chosen as a typical country that fits this condition. The underlying infrastructure of Italy is represented by simplified model of a postal network, abstracted by a graph G = (V, E, c, w).

The results can serve as a basis for modification of the used models for the simulation of networks in the postal sector and as a key that compares the opportunities and results of application of these two models in the conditions large countries.

Keywords

  • optimization
  • postal networks
  • location problems
  • p-median
  • uncapacitated fixed charge location model
Open Access

Assessing the Contribution of Urban Freight Terminals in Last Mile Operations

Published Online: 28 Jun 2016
Page range: 231 - 241

Abstract

Abstract

This paper introduces a multi-stakeholder multi-criteria evaluation framework, which can be used for the assessment of the last mile distribution performance of urban freight terminals. To this end, a comparative analysis is conducted addressing two Greek urban intermodal freight terminals located at the port of Thessaloniki (ThPA) and Kuehne+Nagel (K+N)’s premises. The assessment of the terminals’ performance relies on a tailored multi-criteria Key Performance Indicator (KPI)-based evaluation framework, whereas the selection and significance of the incorporated criteria and KPIs is predetermined by the relevant responsible stakeholders, who imposed their viewpoint through an analytic hierarchy process. Results showed that ThPA was ranked first according to its performance pertaining to the role of an intermodal interchange; still, K+N’s performance index was only 8.5% lower than ThPA’s, while in specific KPIs it seems that it performs in a better way.

Keywords

  • Freight terminals
  • last mile
  • key performance indicators
  • multi-stakeholder
  • multi-criteria
  • sensitivy analysis
  • AHP
  • PROMETHEE
  • GAIA
Open Access

Motorway Network Simulation Using Bluetooth Data

Published Online: 28 Jun 2016
Page range: 242 - 251

Abstract

Abstract

This paper describes a systematic calibration process of a Vissim model, based on data derived from BT detectors. It also provides instructions how to calibrate and validate a highway network model based upon a case study and establishes an example for practitioners that are interested in designing highway networks with micro simulation tools. Within this case study, a 94,5 % proper calibration to all segments was achieved First, an overview of the systematic calibration approach that will be followed is presented. A description of the given datasets follows. Finally, model’s systematic calibration and validation based on BT data from segments under free flow conditions is thoroughly explained. The delivered calibrated Vissim model acts as a test bed, which in combination with other analysis tools can be used for potential future exploitation regarding transportation related purposes.

Keywords

  • simulation
  • highway network
  • Bluetooth data
  • Vissim
  • calibration
7 Articles
Open Access

Performance Availability Assessment of Combined Multi Power Source Traction Drive Considering Real Operational Conditions

Published Online: 28 Jun 2016
Page range: 179 - 191

Abstract

Abststract

The present paper deals with the vehicle’s traction electric drive, consisting of several various electric power sources. One of the main requirements for such systems are the safety and sustainable operations, achieved largely the implementation of an uninterrupted supply of the vehicle’s propulsion system with an electric power.

One way of realization of the required level of operational sustainability is usage of Multi Power Source Traction Drive. This type of vehicle’s propulsion systems is widely applied on the ships, trains, planes, heavy trucks. The most important impact on the sustainability of functioning of the ship’s propulsion system have operational conditions, especially for the cargo ship, operating in Arctic region.

This paper presents the application of the LZ-transform method to assessing the important parameter of the vehicle’s operational sustainability - availability of the multi-state (MSS) Multi Power Source Traction Drive, which includes Diesel-Generators and Gas-Turbine-Generators considering the impact of the real operating conditions.

Straightforward Markov method applied to solve this problem will require building of a system’s model with numerous numbers of states and solve a corresponding system of multiple differential equations. LZ-transform method, drastically simplified the solution.

Keywords

  • Multi Power Source Traction Drive
  • LZ-transform method
  • Multi-state systems
  • Assessing Operational Sustainability
  • Arctic cargo ship
  • Electric Propulsion System
Open Access

OFDM Signal Research with Varied Subcarriers Number

Published Online: 28 Jun 2016
Page range: 192 - 201

Abstract

Abstract

The orthogonal frequency division multiplexing (OFDM) aggregate signal energy characteristics are studied based on the OFDM signal simulation model. The information reliability of OFDM signal is explored for different sets of OFDM subcarrier numbers and varied multiposition keying types (MPK) on OFDM subcarriers. The conditions for optimal gain factor for OFDM signal are described analytically based on the simulation modeling results. The effect and value from using an optimal gain factor for OFDM signal is shown in this paper.

Keywords

  • OFDM
  • simulation
  • subcarriers number
  • multiposition keying
  • BER
  • optimal gain factor
Open Access

Use of Information Intelligent Components for the Analysis of Complex Processes of Marine Energy Systems

Published Online: 28 Jun 2016
Page range: 202 - 211

Abstract

Abstract

Synchronous motors and their modifications (ac converter-fed motor, etc.) enable to develop low-noise, reliable and economically efficient electric drive systems. The construction of up-to-date systems based on the synchronous machines is impossible without development of the computing software incorporating mathematical and computing simulation. In its turn, modelling of the synchronous machines as a rule is based on the equations by Park-Gorev, application of which requires adoption of a series of allowances. These allowances in a number of cases do not permit to obtain adequate results of the simulation coinciding with the results of field experiments of the systems under review. Moreover, while applying the system of equations by Park-Gorev to research the systems including interaction of synchronous machines with semiconducting converters of electric energy it is necessary simulate the process of formation their controlling signals in the sphere of frequency. If the states of converter’s keys are defined not only by controlling impulses but also by the state of currents in the synchronous machines flowing through them, such approach is not reasonable.

Keywords

  • power systems
  • intellectual systems
  • synchronous machines
  • ship
  • simulation
Open Access

Competitive Traffic Assignment in Road Networks

Published Online: 28 Jun 2016
Page range: 212 - 221

Abstract

Abstract

Recently in-vehicle route guidance and information systems are rapidly developing. Such systems are expected to reduce congestion in an urban traffic area. This social benefit is believed to be reached by imposing the route choices on the network users that lead to the system optimum traffic assignment. However, guidance service could be offered by different competitive business companies. Then route choices of different mutually independent groups of users may reject traffic assignment from the system optimum state. In this paper, a game theoretic approach is shown to be very efficient to formalize competitive traffic assignment problem with various groups of users in the form of non-cooperative network game with the Nash equilibrium search. The relationships between the Wardrop’s system optimum associated with the traffic assignment problem and the Nash equilibrium associated with the competitive traffic assignment problem are investigated. Moreover, some related aspects of the Nash equilibrium and the Wardrop’s user equilibrium assignments are also discussed.

Keywords

  • competitive traffic assignment
  • Nash equilibrium
  • system optimum of Wardrop
  • user equilibrium of Wardrop
Open Access

Multiple Approaches of Solving Allocation Problems on Postal Transportation Network in Conditions of Large Countries

Published Online: 28 Jun 2016
Page range: 222 - 230

Abstract

Abstract

The article deals with the optimizing the postal transportation network with two different optimizing methods. The research adopted in this article uses allocation models within graph theory to obtain results for addressed optimization problem. The article presents and compares two types of these models: p-median and uncapacitated fixed charge facility location model. The aim of p-median model is to find the location of P facilities in network, serving all demands in a way ensuring the average transport cost to be minimal. Fixed charge location model approach the issue of facility location based on minimizing the overall costs of implementation of selected variants. The latter this two models are subsequently applied on the postal network to determine the optimal location of postal facilities. These two models are adopted in the condition of large country with area above 300 000 km2. The Italy was chosen as a typical country that fits this condition. The underlying infrastructure of Italy is represented by simplified model of a postal network, abstracted by a graph G = (V, E, c, w).

The results can serve as a basis for modification of the used models for the simulation of networks in the postal sector and as a key that compares the opportunities and results of application of these two models in the conditions large countries.

Keywords

  • optimization
  • postal networks
  • location problems
  • p-median
  • uncapacitated fixed charge location model
Open Access

Assessing the Contribution of Urban Freight Terminals in Last Mile Operations

Published Online: 28 Jun 2016
Page range: 231 - 241

Abstract

Abstract

This paper introduces a multi-stakeholder multi-criteria evaluation framework, which can be used for the assessment of the last mile distribution performance of urban freight terminals. To this end, a comparative analysis is conducted addressing two Greek urban intermodal freight terminals located at the port of Thessaloniki (ThPA) and Kuehne+Nagel (K+N)’s premises. The assessment of the terminals’ performance relies on a tailored multi-criteria Key Performance Indicator (KPI)-based evaluation framework, whereas the selection and significance of the incorporated criteria and KPIs is predetermined by the relevant responsible stakeholders, who imposed their viewpoint through an analytic hierarchy process. Results showed that ThPA was ranked first according to its performance pertaining to the role of an intermodal interchange; still, K+N’s performance index was only 8.5% lower than ThPA’s, while in specific KPIs it seems that it performs in a better way.

Keywords

  • Freight terminals
  • last mile
  • key performance indicators
  • multi-stakeholder
  • multi-criteria
  • sensitivy analysis
  • AHP
  • PROMETHEE
  • GAIA
Open Access

Motorway Network Simulation Using Bluetooth Data

Published Online: 28 Jun 2016
Page range: 242 - 251

Abstract

Abstract

This paper describes a systematic calibration process of a Vissim model, based on data derived from BT detectors. It also provides instructions how to calibrate and validate a highway network model based upon a case study and establishes an example for practitioners that are interested in designing highway networks with micro simulation tools. Within this case study, a 94,5 % proper calibration to all segments was achieved First, an overview of the systematic calibration approach that will be followed is presented. A description of the given datasets follows. Finally, model’s systematic calibration and validation based on BT data from segments under free flow conditions is thoroughly explained. The delivered calibrated Vissim model acts as a test bed, which in combination with other analysis tools can be used for potential future exploitation regarding transportation related purposes.

Keywords

  • simulation
  • highway network
  • Bluetooth data
  • Vissim
  • calibration

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