Rivista e Edizione

Volume 119 (2022): Edizione 1 (January 2022)

Volume 118 (2021): Edizione 1 (January 2021)

Volume 117 (2020): Edizione 1 (January 2020)

Volume 116 (2019): Edizione 12 (December 2019)

Volume 116 (2019): Edizione 11 (November 2019)

Volume 116 (2019): Edizione 10 (October 2019)

Volume 116 (2019): Edizione 9 (September 2019)

Volume 116 (2019): Edizione 8 (August 2019)

Volume 116 (2019): Edizione 7 (July 2019)

Volume 116 (2019): Edizione 6 (June 2019)

Volume 116 (2019): Edizione 5 (May 2019)

Volume 116 (2019): Edizione 4 (April 2019)

Volume 116 (2019): Edizione 3 (March 2019)

Volume 116 (2019): Edizione 2 (February 2019)

Volume 116 (2019): Edizione 1 (January 2019)

Volume 115 (2018): Edizione 12 (December 2018)

Volume 115 (2018): Edizione 11 (November 2018)

Volume 115 (2018): Edizione 10 (October 2018)

Volume 115 (2018): Edizione 9 (September 2018)

Volume 115 (2018): Edizione 8 (August 2018)

Volume 115 (2018): Edizione 7 (July 2018)

Volume 115 (2018): Edizione 6 (June 2018)

Volume 115 (2018): Edizione 5 (May 2018)

Volume 115 (2018): Edizione 4 (April 2018)

Volume 115 (2018): Edizione 3 (March 2018)

Volume 115 (2018): Edizione 2 (February 2018)

Volume 115 (2018): Edizione 1 (January 2018)

Volume 114 (2017): Edizione 11 (November 2017)

Volume 114 (2017): Edizione 10 (October 2017)

Volume 114 (2017): Edizione 9 (September 2017)

Volume 114 (2017): Edizione 8 (August 2017)

Volume 114 (2017): Edizione 7 (July 2017)

Volume 114 (2017): Edizione 6 (June 2017)

Volume 114 (2017): Edizione 5 (May 2017)

Volume 114 (2017): Edizione 4 (April 2017)

Volume 114 (2017): Edizione 3 (March 2017)

Volume 114 (2017): Edizione 2 (February 2017)

Volume 114 (2017): Edizione 1 (January 2017)

Dettagli della rivista
Formato
Rivista
eISSN
2353-737X
Pubblicato per la prima volta
20 May 2020
Periodo di pubblicazione
1 volta all'anno
Lingue
Inglese

Cerca

Volume 115 (2018): Edizione 10 (October 2018)

Dettagli della rivista
Formato
Rivista
eISSN
2353-737X
Pubblicato per la prima volta
20 May 2020
Periodo di pubblicazione
1 volta all'anno
Lingue
Inglese

Cerca

17 Articoli
access type Accesso libero

Modern park as a result of urban space recycling – a review of new york city’s developments

Pubblicato online: 21 May 2020
Pagine: 5 - 21

Astratto

Abstract

The development of organized green areas in the specific circumstances of New York’s “culture of concentration” [1, p. 10] takes place, among others, in areas whose original function has changed or found a new peripheral location. Many projects related to transport, storage, or freight forwarding have been completed in post-industrial areas. The issue of rban space recycling, besides the basic question of adapting the area to a new function, requires a particular reference to the cultural heritage of the place, including its material legacy, which is sometimes difficult to preserve and expose. This article presents characteristic examples of urban recycling in particular districts of New York where the new function of a city park has been overlaid on unused areas, while preserving their characteristic environmental circumstances and cultural identities.

Parole chiave

  • space
  • revitalization
  • gentrification
  • city parks
  • cultural and environmental circumstances
access type Accesso libero

New forms in a historical context. Contemporary architectural interventions in the landscape of the Oder river’s riverfronts in Wrocław’s city centre

Pubblicato online: 21 May 2020
Pagine: 45 - 54

Astratto

Abstract

The author analyses selected examples of contemporary built residential development projects in locations close to the historical city centre of Wrocław that create a new architectural frame around the waterfronts of the Oder River. The ambitious works of architecture, constituting a contemporary interpretation of the atmosphere and tradition of the place, introduce new values into the unique space of the waterfronts, remaining in accord with the new philosophy of cultural heritage.

Parole chiave

  • Wroclaw
  • cultural landscape
  • contemporary architectural interventions
access type Accesso libero

From slums to a model example of revitalisation: overcoming a difficult identity in the renewal process of the district of Hulme in Manchester

Pubblicato online: 21 May 2020
Pagine: 23 - 44

Astratto

Abstract

The paper is devoted to the renewal of inner city districts, burdened with a difficult identity. The analysis focuses on the case study of the district of Hulme in Manchester. Within the perimeter of Hulme the attempts to revitalise the area burdened with bad reputation of the biggest slum in Manchester have been made twice. The paper presents the genesis of the bad reputation of the district, its effect on the degradation of the district, as well as it describes the strategies undertaken during both attempts of the revitalisation of Hulme.

Parole chiave

  • identity
  • revitalisation of inner city districts
  • difficult identity of the place
  • revitalisation of Hulme
access type Accesso libero

Royal residence in Lobzow. Transformations from the 13’th to the 20’th century against the background of the research state analysis in chronological order

Pubblicato online: 21 May 2020
Pagine: 55 - 70

Astratto

Abstract

700 years of the former royal palace in Lobzow’s history is a period of reconstruction and adaptation. Time faded traces of a representative residence and the nineteenth century brought her down. Reconstruction for the Austrian Kadetten Institut replaced the charming ruin with the barracks. Sources regarding the history of Krakow’s Officer Cadet School are very diverse and largely unrecognized. They cover both the architectural object and the entire town where it was located. They concern its ownership status, topography of the area, natural properties and urban values in relation to the capital city of Krakow. The author of this article attempted to characterize the transformation of the royal palace in Lobzow over the centuries, based on an analysis of its state of research.

Parole chiave

  • Łobzów
  • rezydencja królewska
  • zamek
  • pałac królewski
  • przekształcenie zabytku
  • historia pomnika
  • historia Łobzowa
access type Accesso libero

Ensuring the QoS in computer networks through the use of the pay&require multi-agent system and electronic auctions

Pubblicato online: 21 May 2020
Pagine: 71 - 83

Astratto

Abstract

In modern computer networks, agent-based systems are widely used. The very fundamental usage of agents are for management systems e.g. supporting SNMP-based databases and multiple client-server communications. This paper describes the Pay&Require mechanism implementing a multi-agent approach for a QoS-enabled computer network. The unique features of the P&R system are its comprehensive approach to the cooperation of agents dedicated to traffic monitoring, the selective response to the QoS-oriented admission of user requests, event-driven reconfiguration and transmission quality brokerage. The brokerage in quality purchase was based on different models – from a simple reactive agent to an agent with learning capabilities. The presented approach uses auctions in which agents (brokers) can buy quality parameters according to customer requirements. The use of auctions allows the dynamic pricing of data transmission services.

Parole chiave

  • agent negotiations
  • market-based price modelling
  • auctions
  • computer networks
  • quality assurance
  • QoS
  • Pay&Require
access type Accesso libero

Induction motors in traction drives, service tests

Pubblicato online: 21 May 2020
Pagine: 85 - 98

Astratto

Abstract

Electric multiple units (EMUs) EN57 are fitted with two cage induction motors to each bogie. Two motors driving one bogie are supplied from a common DC/AC inverter. These motors become damaged after a short service period; the end-rings start to break away, start to break away. The results of service tests conducted during normal train runs are presented in the paper. The investigation possibilities were limited to recording load currents and vibrations of four motors installed at two bogies of one car. It has been concluded that the reason for rotor winding damage may be traced back to the simultaneous impact of four factors: 1) transmission of load torque by mechanical gearbox; there is a backlash between the pinion mounted at the motor shaft and the toothed gear mounted at the drive bogie axle; 2) rigid assembly of the motor in the bogie frame and vibrations transmitted from the drive wheels to motor; 3) variable components of electromagnetic torque generated by higher harmonics of inverter voltage and current; 4) parallel operation of two unmatched motors supplied from common inverter.

Parole chiave

  • cage induction motors
  • traction drive systems
  • service tests
  • rotor winding failure
access type Accesso libero

Energy efficiency of a railway line supplied by 3 kv supply system – a case study of the application of an inverter in a traction substation

Pubblicato online: 21 May 2020
Pagine: 99 - 110

Astratto

Abstract

Due to energy saving policy in the European Union and development of power electronics technology, one might expect an increase in the use of solutions, such as inverters in the substations of the 3 kV DC power supply system. The paper includes a study case of the analysis of traffic conditions on the use of inverters in 3 kV DC system traction substations so as to send back trains’ braking energy from a DC traction power supply to an AC power supply network. The authors presented possible estimated energy savings for a selected railway line. Furthermore, the character of a power waveform and energy available for transferring from a DC to an AC power supply network was discussed as well. The effectiveness of this solution largely depends on the nature of train traffic, so prior to applying the inverters, a detailed analysis is required.

Parole chiave

  • energy efficiency
  • railway line
  • traction substation
access type Accesso libero

Modeling of contact wire’s de-iceing phenomena using artificial neural networks

Pubblicato online: 21 May 2020
Pagine: 111 - 117

Astratto

Abstract

The article presents results of iced wire’s temperature approximation during process of heating this wire to melt ice. This approximation was implemented in Matlab using a two-layer feedforward artificial neural network (ANN). The results of the approximation are acceptable, but it is possible to improve them.

Parole chiave

  • melting of ice
  • iced wire
  • artificial neural network
access type Accesso libero

Selecting quasi-constant weight code parameters for systems of automatics

Pubblicato online: 21 May 2020
Pagine: 119 - 126

Astratto

Abstract

In this paper, the requirements of quasi-constant weight code parameters are considered for a certain number of encoded messages and for various requirements of noise immunity. An algorithm is proposed for choosing the optimal parameters of a quasi-constant weight code for a given number of encoded messages and a level of noise immunity that would ensure maximum speed of control command transmission.

Parole chiave

  • quasi-constant weight codes
  • communication channel
  • noise immunity
  • speed of control command transmission
access type Accesso libero

High-frequency cascade converter for a dual-system locomotive

Pubblicato online: 21 May 2020
Pagine: 127 - 140

Astratto

Abstract

This article presents the concept for using an LLC resonant converter equipped with a medium-frequency transformer to upgrade the existing EU 07 locomotive into a dual-system vehicle. The work was created which sets out the specification for such an upgrade, but the design was eventually rejected by the investor and it became the subject of a diploma thesis.

Parole chiave

  • LLC resonant converter
  • equipped with medium frequency
  • modernizing transformer
access type Accesso libero

Modifications of the soft switching system resistant to disturbances in control systems of voltage sources inverters

Pubblicato online: 21 May 2020
Pagine: 141 - 155

Astratto

Abstract

Reduction of the switching losses in three-phase voltage source inverters can be achieved by using of soft switching systems that not only increase the efficiency of the inverters, but they also reduce the size of the semiconductor cooling circuits, that is especially important in traction vehicles. The majority of existing soft switching systems have some drawbacks that could be danger for inverter operation in the case of disturbances in control systems. The paper briefly describes the structure, operation principles and results of laboratory tests of the proposed soft switching system. Particular attention has been paid to the specific features of alternative versions of the proposed soft switching system, that allow to improve operating parameters of the basic system.

Parole chiave

  • soft switching
  • switching losses
  • voltage source inverters
  • ZCZVS converters
access type Accesso libero

Simulation of pipeline random response to stray currents effects produced by D.C. traction system

Pubblicato online: 21 May 2020
Pagine: 157 - 170

Astratto

Abstract

The paper presents a method of the simulation of the pipeline potential shift produced by D.C. traction stray currents which are stochastic in character. The calculation model presented is based on the deterministic model used in the earth-return circuit theory combined with the non-deterministic approach based on the Monte Carlo procedure. The model of the equivalent rail with current energization and the concept of superposition allow one to consider more complicated D.C. railway systems using a segmental approximation of the complex railway route and taking into account a number of substations and loads at any location. A locomotive position and a load current are assumed to be independent random variables in the non-deterministic approach. Using simulation program developed random characteristics of a pipeline response e.g. maximum, minimum, median and mean values can be obtained. Hence the pipeline regions more exposed to corrosion risk can be determined.

Parole chiave

  • D.C. traction
  • complex geometry
  • stochastic stray currents
  • earth return circuit
  • pipeline potential shift
  • simulation
  • Monte Carlo method
access type Accesso libero

Experimental research on electrodischarge drilling of high aspect ratio holes in Ti-6AL-4V alloy

Pubblicato online: 21 May 2020
Pagine: 171 - 180

Astratto

Abstract

The drilling of small cylindrical (D < 1 mm) holes with a high ratio of length to diameter (L/D > 10) in difficult-to-cut materials is significantly beyond mechanical drilling capabilities. Electrodischarge machining (EDM) is a good and cost effective alternative in such situations. The machinability of electrodischarge machined material is determined by its thermal and electrical properties; therefore, the high electrical resistivity, the relatively high melting point and low thermal conductivity of Ti-6Al-4V alloy cause problems during the machining of parts made of this material. In this article, the results of experimental research on electrodischarge microdrilling in Grade 5 Ti-6Al-4V alloy are presented. The influence of various machining parameters (pulse time, discharge voltage, current amplitude, dielectric pressure, electrode-tool rotation speed) on key technological factors such as hole depth, side gap, linear tool wear, mean drilling speed and hole taper angle was analysed.

Parole chiave

  • EDM
  • holes with a high ratio of length to diameter
  • drilling
  • titanium
access type Accesso libero

Microstructure of laser-modified electro-sparking coatings

Pubblicato online: 21 May 2020
Pagine: 181 - 186

Astratto

Abstract

The article summarizes research on a method used to improve tribological properties. The paper presents possibilities of using laser surface modification by means of EDM. The performed research confirmed that the concentrated laser beam stream can effectively modify the state of the ESD coating layer, WC-Cu and improve their usability. The work aims to assess the properties of coatings after laser treatment, based on the observation of the newly created structure of the material, the measurement of adhesion and microhardness measurement.

Parole chiave

  • WC-Cu coating
  • laser treatment
  • electrospark deposition
  • surface
access type Accesso libero

Influence of composition of anti-graffiti coating system used in rolling stock on fire end structure properties

Pubblicato online: 21 May 2020
Pagine: 187 - 193

Astratto

Abstract

The paper discusses fire parameters of individual layers of anti-graffiti coating systems proposed for use in rail transport. Modifications and their effect on flammable properties of these coatings have been described. Performed tests included, first of all, parameters such as lateral spread of flame over the surface and heat emission, whose fulfillment proved the most difficult in the previous studies. For this purpose, polyester putties were tested on an epoxy primer. Then, fire parameters for different anti-graffiti systems containing a swelling layer as an additional protective layer were determined.

Parole chiave

  • fire tests of railway materials
  • critical heat flux at extinguishment
  • lateral spread of flame on products
  • cone calorimeter
  • maximum average rate of heat emission
  • fire safety
access type Accesso libero

Influence of laser treatment on properties of high speed tool

Pubblicato online: 21 May 2020
Pagine: 195 - 200

Astratto

Abstract

The paper presents the results of heat treatment tests of HS6-5-2 high speed steel with laser working in continuous mode. The tests used steel in the delivery state as well as steel after fluid treatment aimed at diffusion enrichment of the surface layer with carbon and nitrogen. The aim of the research is to determine changes in the structure of steel enriched with carbon and nitrogen and then subjected to the impact of the laser beam.

Parole chiave

  • laser heat treatment
  • high-speed tool steel
access type Accesso libero

Additive manufacturing of titanium with application of cold spray process

Pubblicato online: 21 May 2020
Pagine: 201 - 207

Astratto

Abstract

Cold spraying is a new technology which can be used in the area of additive manufacturing. This method is suitable for oxygen-sensitive materials, such as titanium. In this paper the microstructure and mechanical properties of cold sprayed titanium deposit were characterized.

Parole chiave

  • additive manufacturing
  • cold spraying
  • titanium
17 Articoli
access type Accesso libero

Modern park as a result of urban space recycling – a review of new york city’s developments

Pubblicato online: 21 May 2020
Pagine: 5 - 21

Astratto

Abstract

The development of organized green areas in the specific circumstances of New York’s “culture of concentration” [1, p. 10] takes place, among others, in areas whose original function has changed or found a new peripheral location. Many projects related to transport, storage, or freight forwarding have been completed in post-industrial areas. The issue of rban space recycling, besides the basic question of adapting the area to a new function, requires a particular reference to the cultural heritage of the place, including its material legacy, which is sometimes difficult to preserve and expose. This article presents characteristic examples of urban recycling in particular districts of New York where the new function of a city park has been overlaid on unused areas, while preserving their characteristic environmental circumstances and cultural identities.

Parole chiave

  • space
  • revitalization
  • gentrification
  • city parks
  • cultural and environmental circumstances
access type Accesso libero

New forms in a historical context. Contemporary architectural interventions in the landscape of the Oder river’s riverfronts in Wrocław’s city centre

Pubblicato online: 21 May 2020
Pagine: 45 - 54

Astratto

Abstract

The author analyses selected examples of contemporary built residential development projects in locations close to the historical city centre of Wrocław that create a new architectural frame around the waterfronts of the Oder River. The ambitious works of architecture, constituting a contemporary interpretation of the atmosphere and tradition of the place, introduce new values into the unique space of the waterfronts, remaining in accord with the new philosophy of cultural heritage.

Parole chiave

  • Wroclaw
  • cultural landscape
  • contemporary architectural interventions
access type Accesso libero

From slums to a model example of revitalisation: overcoming a difficult identity in the renewal process of the district of Hulme in Manchester

Pubblicato online: 21 May 2020
Pagine: 23 - 44

Astratto

Abstract

The paper is devoted to the renewal of inner city districts, burdened with a difficult identity. The analysis focuses on the case study of the district of Hulme in Manchester. Within the perimeter of Hulme the attempts to revitalise the area burdened with bad reputation of the biggest slum in Manchester have been made twice. The paper presents the genesis of the bad reputation of the district, its effect on the degradation of the district, as well as it describes the strategies undertaken during both attempts of the revitalisation of Hulme.

Parole chiave

  • identity
  • revitalisation of inner city districts
  • difficult identity of the place
  • revitalisation of Hulme
access type Accesso libero

Royal residence in Lobzow. Transformations from the 13’th to the 20’th century against the background of the research state analysis in chronological order

Pubblicato online: 21 May 2020
Pagine: 55 - 70

Astratto

Abstract

700 years of the former royal palace in Lobzow’s history is a period of reconstruction and adaptation. Time faded traces of a representative residence and the nineteenth century brought her down. Reconstruction for the Austrian Kadetten Institut replaced the charming ruin with the barracks. Sources regarding the history of Krakow’s Officer Cadet School are very diverse and largely unrecognized. They cover both the architectural object and the entire town where it was located. They concern its ownership status, topography of the area, natural properties and urban values in relation to the capital city of Krakow. The author of this article attempted to characterize the transformation of the royal palace in Lobzow over the centuries, based on an analysis of its state of research.

Parole chiave

  • Łobzów
  • rezydencja królewska
  • zamek
  • pałac królewski
  • przekształcenie zabytku
  • historia pomnika
  • historia Łobzowa
access type Accesso libero

Ensuring the QoS in computer networks through the use of the pay&require multi-agent system and electronic auctions

Pubblicato online: 21 May 2020
Pagine: 71 - 83

Astratto

Abstract

In modern computer networks, agent-based systems are widely used. The very fundamental usage of agents are for management systems e.g. supporting SNMP-based databases and multiple client-server communications. This paper describes the Pay&Require mechanism implementing a multi-agent approach for a QoS-enabled computer network. The unique features of the P&R system are its comprehensive approach to the cooperation of agents dedicated to traffic monitoring, the selective response to the QoS-oriented admission of user requests, event-driven reconfiguration and transmission quality brokerage. The brokerage in quality purchase was based on different models – from a simple reactive agent to an agent with learning capabilities. The presented approach uses auctions in which agents (brokers) can buy quality parameters according to customer requirements. The use of auctions allows the dynamic pricing of data transmission services.

Parole chiave

  • agent negotiations
  • market-based price modelling
  • auctions
  • computer networks
  • quality assurance
  • QoS
  • Pay&Require
access type Accesso libero

Induction motors in traction drives, service tests

Pubblicato online: 21 May 2020
Pagine: 85 - 98

Astratto

Abstract

Electric multiple units (EMUs) EN57 are fitted with two cage induction motors to each bogie. Two motors driving one bogie are supplied from a common DC/AC inverter. These motors become damaged after a short service period; the end-rings start to break away, start to break away. The results of service tests conducted during normal train runs are presented in the paper. The investigation possibilities were limited to recording load currents and vibrations of four motors installed at two bogies of one car. It has been concluded that the reason for rotor winding damage may be traced back to the simultaneous impact of four factors: 1) transmission of load torque by mechanical gearbox; there is a backlash between the pinion mounted at the motor shaft and the toothed gear mounted at the drive bogie axle; 2) rigid assembly of the motor in the bogie frame and vibrations transmitted from the drive wheels to motor; 3) variable components of electromagnetic torque generated by higher harmonics of inverter voltage and current; 4) parallel operation of two unmatched motors supplied from common inverter.

Parole chiave

  • cage induction motors
  • traction drive systems
  • service tests
  • rotor winding failure
access type Accesso libero

Energy efficiency of a railway line supplied by 3 kv supply system – a case study of the application of an inverter in a traction substation

Pubblicato online: 21 May 2020
Pagine: 99 - 110

Astratto

Abstract

Due to energy saving policy in the European Union and development of power electronics technology, one might expect an increase in the use of solutions, such as inverters in the substations of the 3 kV DC power supply system. The paper includes a study case of the analysis of traffic conditions on the use of inverters in 3 kV DC system traction substations so as to send back trains’ braking energy from a DC traction power supply to an AC power supply network. The authors presented possible estimated energy savings for a selected railway line. Furthermore, the character of a power waveform and energy available for transferring from a DC to an AC power supply network was discussed as well. The effectiveness of this solution largely depends on the nature of train traffic, so prior to applying the inverters, a detailed analysis is required.

Parole chiave

  • energy efficiency
  • railway line
  • traction substation
access type Accesso libero

Modeling of contact wire’s de-iceing phenomena using artificial neural networks

Pubblicato online: 21 May 2020
Pagine: 111 - 117

Astratto

Abstract

The article presents results of iced wire’s temperature approximation during process of heating this wire to melt ice. This approximation was implemented in Matlab using a two-layer feedforward artificial neural network (ANN). The results of the approximation are acceptable, but it is possible to improve them.

Parole chiave

  • melting of ice
  • iced wire
  • artificial neural network
access type Accesso libero

Selecting quasi-constant weight code parameters for systems of automatics

Pubblicato online: 21 May 2020
Pagine: 119 - 126

Astratto

Abstract

In this paper, the requirements of quasi-constant weight code parameters are considered for a certain number of encoded messages and for various requirements of noise immunity. An algorithm is proposed for choosing the optimal parameters of a quasi-constant weight code for a given number of encoded messages and a level of noise immunity that would ensure maximum speed of control command transmission.

Parole chiave

  • quasi-constant weight codes
  • communication channel
  • noise immunity
  • speed of control command transmission
access type Accesso libero

High-frequency cascade converter for a dual-system locomotive

Pubblicato online: 21 May 2020
Pagine: 127 - 140

Astratto

Abstract

This article presents the concept for using an LLC resonant converter equipped with a medium-frequency transformer to upgrade the existing EU 07 locomotive into a dual-system vehicle. The work was created which sets out the specification for such an upgrade, but the design was eventually rejected by the investor and it became the subject of a diploma thesis.

Parole chiave

  • LLC resonant converter
  • equipped with medium frequency
  • modernizing transformer
access type Accesso libero

Modifications of the soft switching system resistant to disturbances in control systems of voltage sources inverters

Pubblicato online: 21 May 2020
Pagine: 141 - 155

Astratto

Abstract

Reduction of the switching losses in three-phase voltage source inverters can be achieved by using of soft switching systems that not only increase the efficiency of the inverters, but they also reduce the size of the semiconductor cooling circuits, that is especially important in traction vehicles. The majority of existing soft switching systems have some drawbacks that could be danger for inverter operation in the case of disturbances in control systems. The paper briefly describes the structure, operation principles and results of laboratory tests of the proposed soft switching system. Particular attention has been paid to the specific features of alternative versions of the proposed soft switching system, that allow to improve operating parameters of the basic system.

Parole chiave

  • soft switching
  • switching losses
  • voltage source inverters
  • ZCZVS converters
access type Accesso libero

Simulation of pipeline random response to stray currents effects produced by D.C. traction system

Pubblicato online: 21 May 2020
Pagine: 157 - 170

Astratto

Abstract

The paper presents a method of the simulation of the pipeline potential shift produced by D.C. traction stray currents which are stochastic in character. The calculation model presented is based on the deterministic model used in the earth-return circuit theory combined with the non-deterministic approach based on the Monte Carlo procedure. The model of the equivalent rail with current energization and the concept of superposition allow one to consider more complicated D.C. railway systems using a segmental approximation of the complex railway route and taking into account a number of substations and loads at any location. A locomotive position and a load current are assumed to be independent random variables in the non-deterministic approach. Using simulation program developed random characteristics of a pipeline response e.g. maximum, minimum, median and mean values can be obtained. Hence the pipeline regions more exposed to corrosion risk can be determined.

Parole chiave

  • D.C. traction
  • complex geometry
  • stochastic stray currents
  • earth return circuit
  • pipeline potential shift
  • simulation
  • Monte Carlo method
access type Accesso libero

Experimental research on electrodischarge drilling of high aspect ratio holes in Ti-6AL-4V alloy

Pubblicato online: 21 May 2020
Pagine: 171 - 180

Astratto

Abstract

The drilling of small cylindrical (D < 1 mm) holes with a high ratio of length to diameter (L/D > 10) in difficult-to-cut materials is significantly beyond mechanical drilling capabilities. Electrodischarge machining (EDM) is a good and cost effective alternative in such situations. The machinability of electrodischarge machined material is determined by its thermal and electrical properties; therefore, the high electrical resistivity, the relatively high melting point and low thermal conductivity of Ti-6Al-4V alloy cause problems during the machining of parts made of this material. In this article, the results of experimental research on electrodischarge microdrilling in Grade 5 Ti-6Al-4V alloy are presented. The influence of various machining parameters (pulse time, discharge voltage, current amplitude, dielectric pressure, electrode-tool rotation speed) on key technological factors such as hole depth, side gap, linear tool wear, mean drilling speed and hole taper angle was analysed.

Parole chiave

  • EDM
  • holes with a high ratio of length to diameter
  • drilling
  • titanium
access type Accesso libero

Microstructure of laser-modified electro-sparking coatings

Pubblicato online: 21 May 2020
Pagine: 181 - 186

Astratto

Abstract

The article summarizes research on a method used to improve tribological properties. The paper presents possibilities of using laser surface modification by means of EDM. The performed research confirmed that the concentrated laser beam stream can effectively modify the state of the ESD coating layer, WC-Cu and improve their usability. The work aims to assess the properties of coatings after laser treatment, based on the observation of the newly created structure of the material, the measurement of adhesion and microhardness measurement.

Parole chiave

  • WC-Cu coating
  • laser treatment
  • electrospark deposition
  • surface
access type Accesso libero

Influence of composition of anti-graffiti coating system used in rolling stock on fire end structure properties

Pubblicato online: 21 May 2020
Pagine: 187 - 193

Astratto

Abstract

The paper discusses fire parameters of individual layers of anti-graffiti coating systems proposed for use in rail transport. Modifications and their effect on flammable properties of these coatings have been described. Performed tests included, first of all, parameters such as lateral spread of flame over the surface and heat emission, whose fulfillment proved the most difficult in the previous studies. For this purpose, polyester putties were tested on an epoxy primer. Then, fire parameters for different anti-graffiti systems containing a swelling layer as an additional protective layer were determined.

Parole chiave

  • fire tests of railway materials
  • critical heat flux at extinguishment
  • lateral spread of flame on products
  • cone calorimeter
  • maximum average rate of heat emission
  • fire safety
access type Accesso libero

Influence of laser treatment on properties of high speed tool

Pubblicato online: 21 May 2020
Pagine: 195 - 200

Astratto

Abstract

The paper presents the results of heat treatment tests of HS6-5-2 high speed steel with laser working in continuous mode. The tests used steel in the delivery state as well as steel after fluid treatment aimed at diffusion enrichment of the surface layer with carbon and nitrogen. The aim of the research is to determine changes in the structure of steel enriched with carbon and nitrogen and then subjected to the impact of the laser beam.

Parole chiave

  • laser heat treatment
  • high-speed tool steel
access type Accesso libero

Additive manufacturing of titanium with application of cold spray process

Pubblicato online: 21 May 2020
Pagine: 201 - 207

Astratto

Abstract

Cold spraying is a new technology which can be used in the area of additive manufacturing. This method is suitable for oxygen-sensitive materials, such as titanium. In this paper the microstructure and mechanical properties of cold sprayed titanium deposit were characterized.

Parole chiave

  • additive manufacturing
  • cold spraying
  • titanium

Pianifica la tua conferenza remota con Sciendo