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Zeitschriftendaten
Format
Zeitschrift
eISSN
1338-3973
ISSN
1210-3896
Erstveröffentlichung
23 May 2011
Erscheinungsweise
4 Hefte pro Jahr
Sprachen
Englisch

Suche

Volumen 25 (2017): Heft 4 (December 2017)

Zeitschriftendaten
Format
Zeitschrift
eISSN
1338-3973
ISSN
1210-3896
Erstveröffentlichung
23 May 2011
Erscheinungsweise
4 Hefte pro Jahr
Sprachen
Englisch

Suche

6 Artikel
access type Uneingeschränkter Zugang

Optimisation of Design of Air Inlets in Air Distribution Channels of a Double-Skin Transparent Façade

Online veröffentlicht: 13 Jan 2018
Seitenbereich: 1 - 11

Zusammenfassung

Abstract

This paper reports on an optimization of design of air inlets in naturally ventilated double-skin transparent facades; the design aims at the proper functioning of these facades from the point of view of their aerodynamic and hydrodynamic behaviour. A comparison was made of five different variants of ventilation louvers used in air openings with different shapes, positions and overall geometry. The aerodynamic response of the louvers was determined by 2D simulations using ANSYS software. The hydrodynamic properties were investigated by conducting driven-rain measurements in a large rain chamber at the Slovak University of Technology in Bratislava.

Schlüsselwörter

  • Double-skin façade
  • Cavity
  • Ventilation louvers
  • Aerodynamic resistance
  • Wind-driven rain
access type Uneingeschränkter Zugang

Developing a Model for Forecasting Road Traffic Accident (RTA) Fatalities in Yemen

Online veröffentlicht: 13 Jan 2018
Seitenbereich: 12 - 18

Zusammenfassung

Abstract

The aim of this paper is to develop a model for forecasting RTA fatalities in Yemen. The yearly fatalities was modeled as the dependent variable, while the number of independent variables included the population, number of vehicles, GNP, GDP and Real GDP per capita. It was determined that all these variables are highly correlated with the correlation coefficient (r ≈ 0.9); in order to avoid multicollinearity in the model, a single variable with the highest r value was selected (real GDP per capita). A simple regression model was developed; the model was very good (R2=0.916); however, the residuals were serially correlated. The Prais-Winsten procedure was used to overcome this violation of the regression assumption. The data for a 20-year period from 1991-2010 were analyzed to build the model; the model was validated by using data for the years 2011-2013; the historical fit for the period 1991 - 2011 was very good. Also, the validation for 2011-2013 proved accurate.

Schlüsselwörter

  • RTA Fatalities
  • Forecasting RTA Fatalities
  • RTA Fatalities in Yemen
  • Regression Analysis
  • Prais-Winsten procedure
access type Uneingeschränkter Zugang

Measurement of Flat Slab Deformations by the Multi-Image Photogrammetry Method

Online veröffentlicht: 13 Jan 2018
Seitenbereich: 19 - 25

Zusammenfassung

Abstract

The use of photogrammetry during load tests of building components is a common practise all over the world. It is very effective thanks to its contactless approach, 3D measurement, fast data collection, and partial or full automation of image processing; it can deliver very accurate results. Multi-image convergent photogrammetry supported by artificial coded targets is the most accurate photogrammetric method when the targets are detected in an image with a higher degree of accuracy than a 0.1 pixel. It is possible to achieve an accuracy of 0.03 mm for all the points measured on the object observed if the camera is close enough to the object, and the positions of the camera and the number of shots are precisely planned. This contribution deals with the design of a special hanging frame for a DSLR camera used during the photogrammetric measurement of the deformation of flat concrete slab. The results of the photogrammetric measurements are compared to the results from traditional contact measurement techniques during load tests.

Schlüsselwörter

  • Photogrammetry
  • Deformation measurement
  • Flat slab
  • Strain
  • Load test.
access type Uneingeschränkter Zugang

Improvement of the Accuracy of the Orientation of an Object by Using a Pair of Rotating IMS

Online veröffentlicht: 13 Jan 2018
Seitenbereich: 26 - 33

Zusammenfassung

Abstract

Inertial measurement systems (IMS) belong among navigation systems which permit the monitoring of the position and orientation of an object in three-dimensional space. The functional principle of IMS is based on the integration of the output signal (acceleration and angular rate) of inertial sensors to the actual position and orientation of IMS. This integration causes the rapid accumulation of systematic IMS’s errors, which leads to a rapid increase in position and orientation errors over time. The paper deals with the design of a prototype for a pair of lowcost IMSs, which are regularly rotated around their vertical axis by stepper motors. To eliminate the systematic errors of gyroscopes in the direction of the rotation axis, two counter-rotating IMSs are used. An optimal model of the data processing was developed and presented.

Schlüsselwörter

  • Controlled rotation
  • IMS
  • Gyroscope
  • Systematic error
  • Elimination
  • Base.
access type Uneingeschränkter Zugang

Effect of a Near Fault on the Seismic Response of a Base-Isolated Structure with a Soft Storey

Online veröffentlicht: 13 Jan 2018
Seitenbereich: 34 - 46

Zusammenfassung

Abstract

This study focuses on the soft-storey behavior of RC structures with lead core rubber bearing (LRB) isolation systems under near and far-fault motions. Under near-fault ground motions, seismic isolation devices might perform poorly because of large isolator displacements caused by large velocity and displacement pulses associated with such strong motions. In this study, four different structural models have been designed to study the effect of soft-storey behavior under near-fault and far-fault motions. The seismic analysis for isolated reinforced concrete buildings is carried out using a nonlinear time history analysis method. Inter-story drifts, absolute acceleration, displacement, base shear forces, hysteretic loops and the distribution of plastic hinges are examined as a result of the analysis. These results show that the performance of a base isolated RC structure is more affected by increasing the height of a story under nearfault motion than under far-fault motion.

Schlüsselwörter

  • Soft story
  • Near-fault
  • Far-fault
  • Nonlinear analysis
  • Damage
  • Effective Analyses
access type Uneingeschränkter Zugang

Development of a Web-Based Indoor Navigation System Using an Accelerometer and Gyroscope: A Case Study at The Faculty of Natural Sciences of Comenius University

Online veröffentlicht: 13 Jan 2018
Seitenbereich: 47 - 56

Zusammenfassung

Abstract

As a complex of buildings, the Faculty of Natural Sciences of the Comenius University in Bratislava tends to be difficult to navigate in spite of its size. An indoor navigation application could potentially save a lot of time and frustration. There are currently numerous technologies used in indoor navigation systems. Some of them focus on a high degree of precision and require significant financial investment; others provide only static information about a current location. In this paper we focused on the determination of an approximate location using inertial measurement systems available on most smartphones, i.e., a gyroscope and an accelerometer. The actual position of the device was calculated using “a walk detection method” based on a delayed lack of motion. We have developed an indoor navigation application that relies solely on open source JavaScript libraries to visualize the interior of the building and calculate the shortest path utilizing Dijsktra’s routing algorithm. The application logic is located on the client side, so the software is able to work offline. Our solution represents an accessible lowcost and platform-independent web application that can significantly improve navigation at the Faculty of Natural Sciences. Although our application has been developed on a specific building complex, it could be used in other interiors as well.

Schlüsselwörter

  • Indoor navigation
  • Inertial measurement systems
  • Dijsktra’s routing algorithm
  • Web map application
6 Artikel
access type Uneingeschränkter Zugang

Optimisation of Design of Air Inlets in Air Distribution Channels of a Double-Skin Transparent Façade

Online veröffentlicht: 13 Jan 2018
Seitenbereich: 1 - 11

Zusammenfassung

Abstract

This paper reports on an optimization of design of air inlets in naturally ventilated double-skin transparent facades; the design aims at the proper functioning of these facades from the point of view of their aerodynamic and hydrodynamic behaviour. A comparison was made of five different variants of ventilation louvers used in air openings with different shapes, positions and overall geometry. The aerodynamic response of the louvers was determined by 2D simulations using ANSYS software. The hydrodynamic properties were investigated by conducting driven-rain measurements in a large rain chamber at the Slovak University of Technology in Bratislava.

Schlüsselwörter

  • Double-skin façade
  • Cavity
  • Ventilation louvers
  • Aerodynamic resistance
  • Wind-driven rain
access type Uneingeschränkter Zugang

Developing a Model for Forecasting Road Traffic Accident (RTA) Fatalities in Yemen

Online veröffentlicht: 13 Jan 2018
Seitenbereich: 12 - 18

Zusammenfassung

Abstract

The aim of this paper is to develop a model for forecasting RTA fatalities in Yemen. The yearly fatalities was modeled as the dependent variable, while the number of independent variables included the population, number of vehicles, GNP, GDP and Real GDP per capita. It was determined that all these variables are highly correlated with the correlation coefficient (r ≈ 0.9); in order to avoid multicollinearity in the model, a single variable with the highest r value was selected (real GDP per capita). A simple regression model was developed; the model was very good (R2=0.916); however, the residuals were serially correlated. The Prais-Winsten procedure was used to overcome this violation of the regression assumption. The data for a 20-year period from 1991-2010 were analyzed to build the model; the model was validated by using data for the years 2011-2013; the historical fit for the period 1991 - 2011 was very good. Also, the validation for 2011-2013 proved accurate.

Schlüsselwörter

  • RTA Fatalities
  • Forecasting RTA Fatalities
  • RTA Fatalities in Yemen
  • Regression Analysis
  • Prais-Winsten procedure
access type Uneingeschränkter Zugang

Measurement of Flat Slab Deformations by the Multi-Image Photogrammetry Method

Online veröffentlicht: 13 Jan 2018
Seitenbereich: 19 - 25

Zusammenfassung

Abstract

The use of photogrammetry during load tests of building components is a common practise all over the world. It is very effective thanks to its contactless approach, 3D measurement, fast data collection, and partial or full automation of image processing; it can deliver very accurate results. Multi-image convergent photogrammetry supported by artificial coded targets is the most accurate photogrammetric method when the targets are detected in an image with a higher degree of accuracy than a 0.1 pixel. It is possible to achieve an accuracy of 0.03 mm for all the points measured on the object observed if the camera is close enough to the object, and the positions of the camera and the number of shots are precisely planned. This contribution deals with the design of a special hanging frame for a DSLR camera used during the photogrammetric measurement of the deformation of flat concrete slab. The results of the photogrammetric measurements are compared to the results from traditional contact measurement techniques during load tests.

Schlüsselwörter

  • Photogrammetry
  • Deformation measurement
  • Flat slab
  • Strain
  • Load test.
access type Uneingeschränkter Zugang

Improvement of the Accuracy of the Orientation of an Object by Using a Pair of Rotating IMS

Online veröffentlicht: 13 Jan 2018
Seitenbereich: 26 - 33

Zusammenfassung

Abstract

Inertial measurement systems (IMS) belong among navigation systems which permit the monitoring of the position and orientation of an object in three-dimensional space. The functional principle of IMS is based on the integration of the output signal (acceleration and angular rate) of inertial sensors to the actual position and orientation of IMS. This integration causes the rapid accumulation of systematic IMS’s errors, which leads to a rapid increase in position and orientation errors over time. The paper deals with the design of a prototype for a pair of lowcost IMSs, which are regularly rotated around their vertical axis by stepper motors. To eliminate the systematic errors of gyroscopes in the direction of the rotation axis, two counter-rotating IMSs are used. An optimal model of the data processing was developed and presented.

Schlüsselwörter

  • Controlled rotation
  • IMS
  • Gyroscope
  • Systematic error
  • Elimination
  • Base.
access type Uneingeschränkter Zugang

Effect of a Near Fault on the Seismic Response of a Base-Isolated Structure with a Soft Storey

Online veröffentlicht: 13 Jan 2018
Seitenbereich: 34 - 46

Zusammenfassung

Abstract

This study focuses on the soft-storey behavior of RC structures with lead core rubber bearing (LRB) isolation systems under near and far-fault motions. Under near-fault ground motions, seismic isolation devices might perform poorly because of large isolator displacements caused by large velocity and displacement pulses associated with such strong motions. In this study, four different structural models have been designed to study the effect of soft-storey behavior under near-fault and far-fault motions. The seismic analysis for isolated reinforced concrete buildings is carried out using a nonlinear time history analysis method. Inter-story drifts, absolute acceleration, displacement, base shear forces, hysteretic loops and the distribution of plastic hinges are examined as a result of the analysis. These results show that the performance of a base isolated RC structure is more affected by increasing the height of a story under nearfault motion than under far-fault motion.

Schlüsselwörter

  • Soft story
  • Near-fault
  • Far-fault
  • Nonlinear analysis
  • Damage
  • Effective Analyses
access type Uneingeschränkter Zugang

Development of a Web-Based Indoor Navigation System Using an Accelerometer and Gyroscope: A Case Study at The Faculty of Natural Sciences of Comenius University

Online veröffentlicht: 13 Jan 2018
Seitenbereich: 47 - 56

Zusammenfassung

Abstract

As a complex of buildings, the Faculty of Natural Sciences of the Comenius University in Bratislava tends to be difficult to navigate in spite of its size. An indoor navigation application could potentially save a lot of time and frustration. There are currently numerous technologies used in indoor navigation systems. Some of them focus on a high degree of precision and require significant financial investment; others provide only static information about a current location. In this paper we focused on the determination of an approximate location using inertial measurement systems available on most smartphones, i.e., a gyroscope and an accelerometer. The actual position of the device was calculated using “a walk detection method” based on a delayed lack of motion. We have developed an indoor navigation application that relies solely on open source JavaScript libraries to visualize the interior of the building and calculate the shortest path utilizing Dijsktra’s routing algorithm. The application logic is located on the client side, so the software is able to work offline. Our solution represents an accessible lowcost and platform-independent web application that can significantly improve navigation at the Faculty of Natural Sciences. Although our application has been developed on a specific building complex, it could be used in other interiors as well.

Schlüsselwörter

  • Indoor navigation
  • Inertial measurement systems
  • Dijsktra’s routing algorithm
  • Web map application

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