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Détails du magazine
Format
Magazine
eISSN
1338-3973
ISSN
1338-3973
Première publication
23 May 2011
Période de publication
4 fois par an
Langues
Anglais

Chercher

Volume 21 (2013): Edition 4 (December 2013)

Détails du magazine
Format
Magazine
eISSN
1338-3973
ISSN
1338-3973
Première publication
23 May 2011
Période de publication
4 fois par an
Langues
Anglais

Chercher

6 Articles
Accès libre

Querying Uncertain Data in Geospatial Object-relational Databases Using SQL and Fuzzy Sets

Publié en ligne: 29 Jan 2014
Pages: 1 - 12

Résumé

Abstract

This paper deals with uncertainty modeling in spatial object-relational databases by the use of Structured Query Language (SQL). The fundamental principles of uncertainty modeling by fuzzy sets are applied in the area of geographic information systems (GIS) and spatial databases. A spatial database system includes types of spatial data and implements the spatial extension of SQL. The implementation of the principles of fuzzy logic to spatial databases brings an opportunity for the efficient processing of uncertain data, which is important, especially when using various data sources (e.g., multi-criteria decision making (MCDM) on the basis of heterogeneous spatial data resources). The modeling and data processing of uncertainties are presented in relation to the applicable International Organization for Standardization (ISO) standards (standards of the series 19100 Geographic information) and the relevant specifications of the Open Geospatial Consortium (OGC). The fuzzy spatial query approach is applied and tested on a case study with a fundamental database for GIS in Slovakia.

Mots clés

  • Spatial database
  • SQL
  • GIS
  • uncertainty modeling
  • fuzzy sets
Accès libre

Quality of 3D Models Generated by SFM Technology

Publié en ligne: 29 Jan 2014
Pages: 13 - 24

Résumé

Abstract

Using various types of automation in digital photogrammetry is associated with questions such as the accuracy of a 3D model generated on various types of surfaces and textures, the financial costs of the equipment needed, and also the time costs of the processing. This topic deals with the actual technology of computer vision, which allows the automated exterior orientation of images, camera calibration, and the generation of 3D models directly from images of the object itself, based on the automatic detection of significant points. Detailed testing is done using the Agisoft PhotoScan system, and the camera configuration is solved with respect to the accuracy of the 3D model generated and the time consumption of the calculations for the different types of textures and the different settings for the processing.

Mots clés

  • Computer vision
  • photogrammetry
  • image processing
  • structure from motion
Accès libre

Shear Resistance between Concrete-Concrete Surfaces

Publié en ligne: 29 Jan 2014
Pages: 25 - 34

Résumé

Abstract

The application of precast beams and cast-in-situ structural members cast at different times has been typical of bridges and buildings for many years. A load-bearing frame consists of a set of prestressed precast beams supported by columns and diaphragms joined with an additionally cast slab deck. This article is focused on the theoretical and experimental analyses of the shear resistance at an interface. The first part of the paper deals with the state-of-art knowledge of the composite behaviour of concrete-concrete structures and a comparison of the numerical methods introduced in the relevant standards. In the experimental part, a set of specimens with different interface treatments was tested until failure in order to predict the composite behaviour of coupled beams. The experimental part was compared to the numerical analysis performed by means of FEM basis nonlinear software.

Mots clés

  • Surface modification
  • interface
  • coupling
  • nonlinear analysis
  • effect of shear reinforcement
Accès libre

An Adaptive Displacement Detection Algorithm

Publié en ligne: 29 Jan 2014
Pages: 35 - 40

Résumé

Abstract

During permanent GNSS observations a displacement of the network’s station may occur. Not all changes are significant enough to raise an alarm. However, the critical value of the station’s position change may vary significantly for various reasons, such as the antenna model, receiver or observation interval. The coordinates gained by GNSS methods are also usually characterized by a higher degree of precision of the horizontal components than those of the vertical ones. It is virtually impossible to set a single critical value for each component of each station of the network; therefore, an automatic algorithm evaluating the estimates should be used. The paper suggests an adaptive algorithm using a combination of the Kalman filter and a modified moving average technique to reveal sudden changes in a GNSS station’s position, while allowing it to adapt to long-term changes.

Mots clés

  • Displacement detection
  • Kalman filter
  • adaptive algorithm
Accès libre

Coupled Effect of Elevated Temperature and Cooling Conditions on the Properties of Ground Clay Brick Mortars

Publié en ligne: 29 Jan 2014
Pages: 41 - 50

Résumé

Abstract

When a concrete structure is exposed to fire and cooling, some deterioration in its chemical resistivity and mechanical properties takes place. This deterioration can reach a level at which the structure may have to be thoroughly renovated or completely replaced. In this investigation, four types of cement mortars, ground clay bricks (GCB)/sand namely 0/3, 1/2, 2/1 and 3/0, were used. Three different cement contents were used: 350, 400 and 450 kg/m3. All the mortars were prepared and cured in tap water for 3 months and then kept in laboratory atmospheric conditions up to 6 months. The specimens were subjected to elevated temperatures up to 700°C for 3h and then cooled by three different conditions: water, furnace, and air cooling. The results show that all the mortars subjected to fire, irrespective of cooling mode, suffered a significant reduction in compressive strength. However, the mortars cooled in air exhibited a relativity higher reduction in compressive strength rather than those water or furnace cooled. The mortars containing GCB/sand (3/0) and GCB/sand (1/2) exhibited a relatively higher thermal stability than the others.

Mots clés

  • Ground clay bricks
  • fire resistance
  • XRD
  • microstructure
  • compressive strength
  • and cooling mode
Accès libre

Assessment of Costs of Public Works

Publié en ligne: 29 Jan 2014
Pages: 51 - 60

Résumé

Abstract

This article summarizes the results of the preparation, realization and financing of the road infrastructure in Slovakia. Inconsistencies exist when working with costs, budgetary indicators, etc., resulting in the creation of unrealistic cost indicators that are unusable in practice. The results are not reliable, and their use for cost planning in construction preparations, comparisons of construction costs, etc., can be problematic. The proposed solution would be to harmonize the recommended classification of construction works (Methodical Guidelines of the Construction and Regional Development Ministry No. 1/2004) with the classification of the construction features in the Ministry’s Decree No. 83/2008.

Mots clés

  • Road infrastructure in the SK
  • public works
  • investment process
  • prices
  • cost
6 Articles
Accès libre

Querying Uncertain Data in Geospatial Object-relational Databases Using SQL and Fuzzy Sets

Publié en ligne: 29 Jan 2014
Pages: 1 - 12

Résumé

Abstract

This paper deals with uncertainty modeling in spatial object-relational databases by the use of Structured Query Language (SQL). The fundamental principles of uncertainty modeling by fuzzy sets are applied in the area of geographic information systems (GIS) and spatial databases. A spatial database system includes types of spatial data and implements the spatial extension of SQL. The implementation of the principles of fuzzy logic to spatial databases brings an opportunity for the efficient processing of uncertain data, which is important, especially when using various data sources (e.g., multi-criteria decision making (MCDM) on the basis of heterogeneous spatial data resources). The modeling and data processing of uncertainties are presented in relation to the applicable International Organization for Standardization (ISO) standards (standards of the series 19100 Geographic information) and the relevant specifications of the Open Geospatial Consortium (OGC). The fuzzy spatial query approach is applied and tested on a case study with a fundamental database for GIS in Slovakia.

Mots clés

  • Spatial database
  • SQL
  • GIS
  • uncertainty modeling
  • fuzzy sets
Accès libre

Quality of 3D Models Generated by SFM Technology

Publié en ligne: 29 Jan 2014
Pages: 13 - 24

Résumé

Abstract

Using various types of automation in digital photogrammetry is associated with questions such as the accuracy of a 3D model generated on various types of surfaces and textures, the financial costs of the equipment needed, and also the time costs of the processing. This topic deals with the actual technology of computer vision, which allows the automated exterior orientation of images, camera calibration, and the generation of 3D models directly from images of the object itself, based on the automatic detection of significant points. Detailed testing is done using the Agisoft PhotoScan system, and the camera configuration is solved with respect to the accuracy of the 3D model generated and the time consumption of the calculations for the different types of textures and the different settings for the processing.

Mots clés

  • Computer vision
  • photogrammetry
  • image processing
  • structure from motion
Accès libre

Shear Resistance between Concrete-Concrete Surfaces

Publié en ligne: 29 Jan 2014
Pages: 25 - 34

Résumé

Abstract

The application of precast beams and cast-in-situ structural members cast at different times has been typical of bridges and buildings for many years. A load-bearing frame consists of a set of prestressed precast beams supported by columns and diaphragms joined with an additionally cast slab deck. This article is focused on the theoretical and experimental analyses of the shear resistance at an interface. The first part of the paper deals with the state-of-art knowledge of the composite behaviour of concrete-concrete structures and a comparison of the numerical methods introduced in the relevant standards. In the experimental part, a set of specimens with different interface treatments was tested until failure in order to predict the composite behaviour of coupled beams. The experimental part was compared to the numerical analysis performed by means of FEM basis nonlinear software.

Mots clés

  • Surface modification
  • interface
  • coupling
  • nonlinear analysis
  • effect of shear reinforcement
Accès libre

An Adaptive Displacement Detection Algorithm

Publié en ligne: 29 Jan 2014
Pages: 35 - 40

Résumé

Abstract

During permanent GNSS observations a displacement of the network’s station may occur. Not all changes are significant enough to raise an alarm. However, the critical value of the station’s position change may vary significantly for various reasons, such as the antenna model, receiver or observation interval. The coordinates gained by GNSS methods are also usually characterized by a higher degree of precision of the horizontal components than those of the vertical ones. It is virtually impossible to set a single critical value for each component of each station of the network; therefore, an automatic algorithm evaluating the estimates should be used. The paper suggests an adaptive algorithm using a combination of the Kalman filter and a modified moving average technique to reveal sudden changes in a GNSS station’s position, while allowing it to adapt to long-term changes.

Mots clés

  • Displacement detection
  • Kalman filter
  • adaptive algorithm
Accès libre

Coupled Effect of Elevated Temperature and Cooling Conditions on the Properties of Ground Clay Brick Mortars

Publié en ligne: 29 Jan 2014
Pages: 41 - 50

Résumé

Abstract

When a concrete structure is exposed to fire and cooling, some deterioration in its chemical resistivity and mechanical properties takes place. This deterioration can reach a level at which the structure may have to be thoroughly renovated or completely replaced. In this investigation, four types of cement mortars, ground clay bricks (GCB)/sand namely 0/3, 1/2, 2/1 and 3/0, were used. Three different cement contents were used: 350, 400 and 450 kg/m3. All the mortars were prepared and cured in tap water for 3 months and then kept in laboratory atmospheric conditions up to 6 months. The specimens were subjected to elevated temperatures up to 700°C for 3h and then cooled by three different conditions: water, furnace, and air cooling. The results show that all the mortars subjected to fire, irrespective of cooling mode, suffered a significant reduction in compressive strength. However, the mortars cooled in air exhibited a relativity higher reduction in compressive strength rather than those water or furnace cooled. The mortars containing GCB/sand (3/0) and GCB/sand (1/2) exhibited a relatively higher thermal stability than the others.

Mots clés

  • Ground clay bricks
  • fire resistance
  • XRD
  • microstructure
  • compressive strength
  • and cooling mode
Accès libre

Assessment of Costs of Public Works

Publié en ligne: 29 Jan 2014
Pages: 51 - 60

Résumé

Abstract

This article summarizes the results of the preparation, realization and financing of the road infrastructure in Slovakia. Inconsistencies exist when working with costs, budgetary indicators, etc., resulting in the creation of unrealistic cost indicators that are unusable in practice. The results are not reliable, and their use for cost planning in construction preparations, comparisons of construction costs, etc., can be problematic. The proposed solution would be to harmonize the recommended classification of construction works (Methodical Guidelines of the Construction and Regional Development Ministry No. 1/2004) with the classification of the construction features in the Ministry’s Decree No. 83/2008.

Mots clés

  • Road infrastructure in the SK
  • public works
  • investment process
  • prices
  • cost

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