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Volume 7 (2012): Issue 1 (June 2012)

Journal Details
Format
Journal
eISSN
1338-7278
ISSN
1338-7278
First Published
29 Mar 2013
Publication timeframe
2 times per year
Languages
English

Search

Volume 7 (2012): Issue 2 (November 2012)

Journal Details
Format
Journal
eISSN
1338-7278
ISSN
1338-7278
First Published
29 Mar 2013
Publication timeframe
2 times per year
Languages
English

Search

12 Articles
Open Access

Analysis and Load-carrying Capacity Estimation of Existing Railway Filler-beam Deck Bridges

Published Online: 15 Dec 2012
Page range: 5 - 14

Abstract

Abstract

In the paper, the actual condition of several existing concrete railway bridges with encased steel beams is discussed. This structural type represents relatively often solution for small span railway bridges in Slovakia. The main conclusions from inspections and in-situ diagnostics are published together with the results of the loadcarrying capacity calculation on the basis of new European codes. Despite of well-known disadvantages, the bridges with filler-beam decks are still demanded by railway authorities because of their big stiffness and small construction depth.

Keywords

  • filler-beam deck bridge
  • diagnostics
  • design and reconstruction of bridges with encased beams
Open Access

Heating of the Natural Gas at the Gas-distributive Installation

Published Online: 15 Dec 2012
Page range: 15 - 22

Abstract

Abstract

Heating of natural gas on the gas-distributive installations is carried out for prevention of creation of gas hydrates in gas pressure controller. There are a few methods of heating of natural gas: complete heating of gas and heating of gas pressure controller. The indicated methods have a row of failings, the delivered from which is possible at the use of vortex tube. Work of vortex tube consists of the simultaneous making of two streams: heated and frappe. The heated stream is used for a serve on a gas pressure controller which shuts out it freezing. Little price, insignificant sizes, absence of motive details helps to use a vortex tube for heating of natural gas on the gasdistributive installations.

Keywords

  • gas-distributive installations
  • gas pressure controller
  • heating of natural gas
  • vortex tube
  • heated stream.
Open Access

Rope of Cyclical Helical Surfaces

Published Online: 15 Dec 2012
Page range: 23 - 32

Abstract

Abstract

This paper describes one method for modeling the rope of cyclical helical surfaces as surfaces of technical practice. The cyclical helical surfaces are generated by continuous movement of the circle together with the moving trihedron of the helix along this helix. The rope is composed of equal sets of cyclical surfaces in two layers. In this paper there is described the creation of straight and helical rope and vector functions of the surfaces in the rope are derived. The author visualizes the resulting surfaces in the rope obtained by its parametric approach in the MAPLE program.

Keywords

  • cyclical helical surface
  • helix
  • vector function of curve and surface
  • revolution
Open Access

Geometry and Modeling of the Oval Strand of n0+(2n0+4)+n2 Type

Published Online: 15 Dec 2012
Page range: 33 - 40

Abstract

Abstract

A wire rope is a structure composed of many individual wires. The wires form two major structural elements: the strand core and the layers of the strand. There may be different shapes of strands in the rope depending on the shape of strand core. The paper deals with the mathematical geometric modeling of the oval wire strand created of n0 + (2n0 + 4) + n2 wires. The number and diameter of the core wires are the initial data. The mathematical representation is in form of parametric equations of the wire axes. The equations are implemented in the Pro/Engineer Wildfire V5 software for creating the geometrical model of the strand.

Keywords

  • wire rope
  • strand of a rope
  • oval strand
  • geometrical model
Open Access

Environmental Risk Assessment for Landscape - ecological Planning in the City Vranov nad Topľou

Published Online: 15 Dec 2012
Page range: 41 - 50

Abstract

Abstract

Pollution of the environment components in many cases presents unacceptable risks to human health and the environment. Risk analysis is one of the tools which help to find a socially acceptable level of the environmental quality. Evaluation of the environmental impacts can be the base for the optimal spatial arrangement and functional use of territory - landscape optimization. In Slovakia, LANDEP methodology based on the principles of sustainable development, is very often used for landscape planning. The paper deals with environmental risk assessment of components of environment (air, water, soil, waste, etc.). The results are used as a base for design of the optimal spatial setting and functional utilization of the land - landscape optimization.

Keywords

  • environmental risk
  • risk assessment
  • landscape planning
  • land optimization
Open Access

Investigation of Sandwich Panel Parameters Influence on its Natural Frequencies

Published Online: 15 Dec 2012
Page range: 51 - 58

Abstract

Abstract

In the paper the parametric study of free vibration analysis of sandwich panel is presented. Effects of the face sheet material, as well as those related to the ply-thickness, core thickness and length of the panel are investigated. There are used approaches based on the first order shear deformation theory. Natural frequencies of sandwich panel are calculated by using analytical solution, which is compared with A NSYS results.

Keywords

  • parametric study
  • free vibration
  • face sheet
  • core
  • natural frequency
Open Access

Multicriteria analysis in hazards assessment in Libya

Published Online: 15 Dec 2012
Page range: 59 - 70

Abstract

Abstract

Environmental hazards (natural and man-made) have always constituted problem in many developing and developed countries. Many applications proved that these problems could be solved through planning studies and detailed information about these prone areas. Determining time and location and size of the problem are important for decision makers for planning and management activities. It is important to know the risk represented by those hazards and take actions to protect against them. Multicriteria analysis methods - Analytic hierarchy process, Pairwise comparison, Ranking method are used to analyse which is the most dangerous hazard facing Libya country. The multicriteria analysis ends with a more or less stable ranking of the given alternatives and hence a recommendation as to which alternative(s) problems should be preferred. Regarding our problem of environmental risk assessment, the result will be a ranking or categorisation of hazards with regard to their risk level.

Keywords

  • environmental risk
  • multicriteria analysis
  • Analytic hierarchy process
  • Pairwise comparison
  • Ranking method
Open Access

Linear Closed-form Solution and Finite-element Analysis of an Active Tensegrity Unit

Published Online: 15 Dec 2012
Page range: 71 - 78

Abstract

Abstract

Results of the linear closed form solution of an active or adaptive tensegrity unit, as well as its numerical analysis using finite element method are presented in the paper. The shape of the unit is an octahedral cell with a square base and it is formed by thirteen members (four bottom and four top cables, four edge struts and one central strut). The central strut is designed as an actuator that allows for an adjustment of the shape of the unit which leads to changes of tensile forces in the cables. Due to the diagonal symmetry of the 3D tensegrity unit the closed-form analysis is based on the 2D solution of the equivalent planar biconvex cable system with one central strut under a vertical point load.

Keywords

  • cables
  • active member
  • tensegrity unit
  • active structure
  • cable system
  • closed-form solution
Open Access

The Firing Temperature of Romanesque Brick from Pác

Published Online: 15 Dec 2012
Page range: 79 - 86

Abstract

Abstract

A pavement brick taken from a Romanesque part of the church in Pác, in the Trnava County, Slovakia, was investigated by x-ray diffraction analysis (XRD) and thermal analyses as differential thermal analysis (DTA), thermogravimetry (TG) and thermodilatometry (TD). It was found that the brick contained dehydroxylated illitic clay, calcite and quartz. As revealed, dehydroxylation was completely finished and no redehydroxylation was observed. Partial decomposition of calcite was also found. The estimated firing temperature is between 600 °C and 700 °C.

Keywords

  • building ceramics
  • ancient ceramics
  • firing
Open Access

An Energetic Approach for Numerical Analysis of an Interface crack in Shearing Mode

Published Online: 15 Dec 2012
Page range: 87 - 98

Abstract

Abstract

A mathematical model of a layered structure and initiation and growth of interface cracks are presented. A numerical approach for solving this problem is described, with the emphasis to the analysis of a shearing-mode crack. The model defines a scalar damage variable in the interface and also plastic tangential slip, which increases the fracture toughness in the shearing crack mode. An energetic formulation governing the adhesive damage until it breaks is proposed. The approach is also tested numerically to demonstrate the behaviour of the model and to assess its suitability in a particular physical situation.

Keywords

  • interface crack
  • interface plasticity
  • energetic approach
  • quadratic programming
Open Access

The Annual Temperature Regime of Natural Physical Cavity and New Possibilities of its Energy Utilization

Published Online: 15 Dec 2012
Page range: 99 - 106

Abstract

Abstract

Natural physical cavity. Quantification of annual temperature regime of natural physical cavity by in-situ experiment. Annual course of temperature of outdoor climate. Annual course of maximum temperature of natural physical cavity of optimal south-west orientation. Concept of new possibilities for energy utilization of air from natural physical cavities. Two-stage system for utilization of renewable energy sources.

Keywords

  • natural physical cavity
  • double-skin transparent faced
  • experiment in-situ
  • renewable energy sources
Open Access

Selection of Heating System at the Reconstruction of a Family House

Published Online: 15 Dec 2012
Page range: 107 - 114

Abstract

Abstract

The work deals with the reconstruction of a family house on the part of energy for heating need. The attention was devoted to comparise individual alternatives, which are possible to realise in assessed house. In the first part of the work, the attention is devoted to describing object and to heat loses values before and after the measurements. Then alternatives of heating their annual costs for heat production and for amount of fuel, invested costs and the portion of invested and overall are particularly characterized. In the part: The economical evaluation of the comparised alternatives, simple return of investments outputs, discount time of return, net actual value and yield rate are. These values give information about the expedience of applications of individual alternatives by economical aspect.

Keywords

  • heating systems
  • condensing gas boiler
  • heat pump
  • biomass
12 Articles
Open Access

Analysis and Load-carrying Capacity Estimation of Existing Railway Filler-beam Deck Bridges

Published Online: 15 Dec 2012
Page range: 5 - 14

Abstract

Abstract

In the paper, the actual condition of several existing concrete railway bridges with encased steel beams is discussed. This structural type represents relatively often solution for small span railway bridges in Slovakia. The main conclusions from inspections and in-situ diagnostics are published together with the results of the loadcarrying capacity calculation on the basis of new European codes. Despite of well-known disadvantages, the bridges with filler-beam decks are still demanded by railway authorities because of their big stiffness and small construction depth.

Keywords

  • filler-beam deck bridge
  • diagnostics
  • design and reconstruction of bridges with encased beams
Open Access

Heating of the Natural Gas at the Gas-distributive Installation

Published Online: 15 Dec 2012
Page range: 15 - 22

Abstract

Abstract

Heating of natural gas on the gas-distributive installations is carried out for prevention of creation of gas hydrates in gas pressure controller. There are a few methods of heating of natural gas: complete heating of gas and heating of gas pressure controller. The indicated methods have a row of failings, the delivered from which is possible at the use of vortex tube. Work of vortex tube consists of the simultaneous making of two streams: heated and frappe. The heated stream is used for a serve on a gas pressure controller which shuts out it freezing. Little price, insignificant sizes, absence of motive details helps to use a vortex tube for heating of natural gas on the gasdistributive installations.

Keywords

  • gas-distributive installations
  • gas pressure controller
  • heating of natural gas
  • vortex tube
  • heated stream.
Open Access

Rope of Cyclical Helical Surfaces

Published Online: 15 Dec 2012
Page range: 23 - 32

Abstract

Abstract

This paper describes one method for modeling the rope of cyclical helical surfaces as surfaces of technical practice. The cyclical helical surfaces are generated by continuous movement of the circle together with the moving trihedron of the helix along this helix. The rope is composed of equal sets of cyclical surfaces in two layers. In this paper there is described the creation of straight and helical rope and vector functions of the surfaces in the rope are derived. The author visualizes the resulting surfaces in the rope obtained by its parametric approach in the MAPLE program.

Keywords

  • cyclical helical surface
  • helix
  • vector function of curve and surface
  • revolution
Open Access

Geometry and Modeling of the Oval Strand of n0+(2n0+4)+n2 Type

Published Online: 15 Dec 2012
Page range: 33 - 40

Abstract

Abstract

A wire rope is a structure composed of many individual wires. The wires form two major structural elements: the strand core and the layers of the strand. There may be different shapes of strands in the rope depending on the shape of strand core. The paper deals with the mathematical geometric modeling of the oval wire strand created of n0 + (2n0 + 4) + n2 wires. The number and diameter of the core wires are the initial data. The mathematical representation is in form of parametric equations of the wire axes. The equations are implemented in the Pro/Engineer Wildfire V5 software for creating the geometrical model of the strand.

Keywords

  • wire rope
  • strand of a rope
  • oval strand
  • geometrical model
Open Access

Environmental Risk Assessment for Landscape - ecological Planning in the City Vranov nad Topľou

Published Online: 15 Dec 2012
Page range: 41 - 50

Abstract

Abstract

Pollution of the environment components in many cases presents unacceptable risks to human health and the environment. Risk analysis is one of the tools which help to find a socially acceptable level of the environmental quality. Evaluation of the environmental impacts can be the base for the optimal spatial arrangement and functional use of territory - landscape optimization. In Slovakia, LANDEP methodology based on the principles of sustainable development, is very often used for landscape planning. The paper deals with environmental risk assessment of components of environment (air, water, soil, waste, etc.). The results are used as a base for design of the optimal spatial setting and functional utilization of the land - landscape optimization.

Keywords

  • environmental risk
  • risk assessment
  • landscape planning
  • land optimization
Open Access

Investigation of Sandwich Panel Parameters Influence on its Natural Frequencies

Published Online: 15 Dec 2012
Page range: 51 - 58

Abstract

Abstract

In the paper the parametric study of free vibration analysis of sandwich panel is presented. Effects of the face sheet material, as well as those related to the ply-thickness, core thickness and length of the panel are investigated. There are used approaches based on the first order shear deformation theory. Natural frequencies of sandwich panel are calculated by using analytical solution, which is compared with A NSYS results.

Keywords

  • parametric study
  • free vibration
  • face sheet
  • core
  • natural frequency
Open Access

Multicriteria analysis in hazards assessment in Libya

Published Online: 15 Dec 2012
Page range: 59 - 70

Abstract

Abstract

Environmental hazards (natural and man-made) have always constituted problem in many developing and developed countries. Many applications proved that these problems could be solved through planning studies and detailed information about these prone areas. Determining time and location and size of the problem are important for decision makers for planning and management activities. It is important to know the risk represented by those hazards and take actions to protect against them. Multicriteria analysis methods - Analytic hierarchy process, Pairwise comparison, Ranking method are used to analyse which is the most dangerous hazard facing Libya country. The multicriteria analysis ends with a more or less stable ranking of the given alternatives and hence a recommendation as to which alternative(s) problems should be preferred. Regarding our problem of environmental risk assessment, the result will be a ranking or categorisation of hazards with regard to their risk level.

Keywords

  • environmental risk
  • multicriteria analysis
  • Analytic hierarchy process
  • Pairwise comparison
  • Ranking method
Open Access

Linear Closed-form Solution and Finite-element Analysis of an Active Tensegrity Unit

Published Online: 15 Dec 2012
Page range: 71 - 78

Abstract

Abstract

Results of the linear closed form solution of an active or adaptive tensegrity unit, as well as its numerical analysis using finite element method are presented in the paper. The shape of the unit is an octahedral cell with a square base and it is formed by thirteen members (four bottom and four top cables, four edge struts and one central strut). The central strut is designed as an actuator that allows for an adjustment of the shape of the unit which leads to changes of tensile forces in the cables. Due to the diagonal symmetry of the 3D tensegrity unit the closed-form analysis is based on the 2D solution of the equivalent planar biconvex cable system with one central strut under a vertical point load.

Keywords

  • cables
  • active member
  • tensegrity unit
  • active structure
  • cable system
  • closed-form solution
Open Access

The Firing Temperature of Romanesque Brick from Pác

Published Online: 15 Dec 2012
Page range: 79 - 86

Abstract

Abstract

A pavement brick taken from a Romanesque part of the church in Pác, in the Trnava County, Slovakia, was investigated by x-ray diffraction analysis (XRD) and thermal analyses as differential thermal analysis (DTA), thermogravimetry (TG) and thermodilatometry (TD). It was found that the brick contained dehydroxylated illitic clay, calcite and quartz. As revealed, dehydroxylation was completely finished and no redehydroxylation was observed. Partial decomposition of calcite was also found. The estimated firing temperature is between 600 °C and 700 °C.

Keywords

  • building ceramics
  • ancient ceramics
  • firing
Open Access

An Energetic Approach for Numerical Analysis of an Interface crack in Shearing Mode

Published Online: 15 Dec 2012
Page range: 87 - 98

Abstract

Abstract

A mathematical model of a layered structure and initiation and growth of interface cracks are presented. A numerical approach for solving this problem is described, with the emphasis to the analysis of a shearing-mode crack. The model defines a scalar damage variable in the interface and also plastic tangential slip, which increases the fracture toughness in the shearing crack mode. An energetic formulation governing the adhesive damage until it breaks is proposed. The approach is also tested numerically to demonstrate the behaviour of the model and to assess its suitability in a particular physical situation.

Keywords

  • interface crack
  • interface plasticity
  • energetic approach
  • quadratic programming
Open Access

The Annual Temperature Regime of Natural Physical Cavity and New Possibilities of its Energy Utilization

Published Online: 15 Dec 2012
Page range: 99 - 106

Abstract

Abstract

Natural physical cavity. Quantification of annual temperature regime of natural physical cavity by in-situ experiment. Annual course of temperature of outdoor climate. Annual course of maximum temperature of natural physical cavity of optimal south-west orientation. Concept of new possibilities for energy utilization of air from natural physical cavities. Two-stage system for utilization of renewable energy sources.

Keywords

  • natural physical cavity
  • double-skin transparent faced
  • experiment in-situ
  • renewable energy sources
Open Access

Selection of Heating System at the Reconstruction of a Family House

Published Online: 15 Dec 2012
Page range: 107 - 114

Abstract

Abstract

The work deals with the reconstruction of a family house on the part of energy for heating need. The attention was devoted to comparise individual alternatives, which are possible to realise in assessed house. In the first part of the work, the attention is devoted to describing object and to heat loses values before and after the measurements. Then alternatives of heating their annual costs for heat production and for amount of fuel, invested costs and the portion of invested and overall are particularly characterized. In the part: The economical evaluation of the comparised alternatives, simple return of investments outputs, discount time of return, net actual value and yield rate are. These values give information about the expedience of applications of individual alternatives by economical aspect.

Keywords

  • heating systems
  • condensing gas boiler
  • heat pump
  • biomass

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