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Volumen 12 (2018): Heft 4 (December 2018)

Volumen 12 (2018): Heft 3 (September 2018)

Volumen 12 (2018): Heft 2 (June 2018)

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Volumen 11 (2017): Heft 3 (September 2017)

Volumen 11 (2017): Heft 2 (June 2017)

Volumen 11 (2017): Heft 1 (March 2017)

Volumen 10 (2016): Heft 4 (December 2016)

Volumen 10 (2016): Heft 3 (September 2016)

Volumen 10 (2016): Heft 2 (June 2016)

Volumen 10 (2016): Heft 1 (March 2016)

Volumen 9 (2015): Heft 4 (December 2015)

Volumen 9 (2015): Heft 3 (September 2015)

Volumen 9 (2015): Heft 2 (June 2015)

Volumen 9 (2015): Heft 1 (March 2015)

Volumen 8 (2014): Heft 4 (December 2014)

Volumen 8 (2014): Heft 3 (September 2014)

Volumen 8 (2014): Heft 2 (June 2014)

Volumen 8 (2014): Heft 1 (March 2014)

Volumen 7 (2013): Heft 4 (December 2013)

Volumen 7 (2013): Heft 3 (September 2013)

Volumen 7 (2013): Heft 2 (June 2013)

Volumen 7 (2013): Heft 1 (March 2013)

Zeitschriftendaten
Format
Zeitschrift
eISSN
2300-5319
Erstveröffentlichung
22 Jan 2014
Erscheinungsweise
4 Hefte pro Jahr
Sprachen
Englisch

Suche

Volumen 8 (2014): Heft 4 (December 2014)

Zeitschriftendaten
Format
Zeitschrift
eISSN
2300-5319
Erstveröffentlichung
22 Jan 2014
Erscheinungsweise
4 Hefte pro Jahr
Sprachen
Englisch

Suche

10 Artikel
access type Uneingeschränkter Zugang

Diagnosis of Discrete-Time Singularly Perturbed Systems Based on Slow Subsystem

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 175 - 180

Zusammenfassung

Abstract

This paper deals with the diagnosis of discrete-time singularly perturbed systems presenting two time scales property. Parity space method is considered to generate the fault detection residual. The focus is in two directions. First, we discuss the residual illconditioning caused by the singular perturbation parameter. Then, the use of the slow subsystem is considered to make the fault diagnosis easier. It is shown that the designed diagnostic algorithm based on reduced order model is close to the one synthesized using the full order system. The developed approach aims at reducing the computational load and the ill-conditioning for stiff residual generation problem. Two examples of application are used to demonstrate the efficiency of the proposed method.

Keywords

  • Discrete-Time Singularly Perturbed System
  • Two Time Scales Property
  • Model Based Fault Diagnosis
  • Parity Space Approach
  • Slow Subsystem
access type Uneingeschränkter Zugang

The Impact of the FLC Controller’s Settings on the Precision of the Positioning of a Payload Transferred by a Mobile Crane

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 181 - 184

Zusammenfassung

Abstract

The paper presents a model of a control system of the slewing motion of a mobile crane in which the FLC controller was used, and then selected results of the numerical simulations of this model were presented. The influence of this controller’s settings on the precision with which the payload is positioned after it has been transferred to a target point for different angles of rotation of the jib, different lengths of the rope and different input signals of the controller was investigated.

Keywords

  • Mobile Crane
  • FLC Controller
access type Uneingeschränkter Zugang

Numerical Analysis of Temperature Field in a Disc Brake at Different Cover Angle of the Pad

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 185 - 188

Zusammenfassung

Abstract

In the paper an influence of the cover angle of the pad on temperature fields of the components of the disc brake is studied. A three-dimensional finite element (FE) model of the pad-disc system was developed at the condition of equal temperatures on the contacting surfaces. Calculations were carried out for a single braking process at constant deceleration assuming that the contact pressure corresponds with the cover angle of the pad so that the moment of friction is equal in each case analysed. Evolutions and distributions of temperature both for the contact surface of the pad and the disc were computed and shown.

Keywords

  • Temperature
  • Disc Brake
  • Cover Angle Of The Pad
  • Finite Element Method
access type Uneingeschränkter Zugang

The Impact of the Support System’s Kinematic Structure on Selected Kinematic and Dynamic Quantities of an Experimental Crane

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 189 - 193

Zusammenfassung

Abstract

This paper presents a comparative analysis of two kinematic structures of the support system (with supports with bilateral and unilateral constraints), which were used in an experimental model of a crane. The computational model was developed by using the ADAMS software. The impact of the kinematic structure of the support system on selected kinematic and dynamic values that were recorded during the slewing motion was analysed. It was found, among other things, that an increased number of degrees of freedom of the support system leads to multiple distortions of time characteristics of kinematic and dynamic quantities.

Keywords

  • Experimental Crane
  • Multi-Body Systems
  • Supports
  • Unilateral Constraints
  • Bilateral Constraints
access type Uneingeschränkter Zugang

Examination of the Effect of Psychophysical Factors on the Quality of Human Gait Recognition

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 194 - 198

Zusammenfassung

Abstract

The paper presents an analysis concerning the influence of selected psychophysical parameters on the quality of human gait recognition. The following factors have been taken into account: body height (BH), body weight (BW), the emotional condition of the respondent, the physical condition of the respondent, previous injuries or dysfunctions of the locomotive system. The study was based on data measuring the ground reaction forces (GRF) among 179 participants (3 315 gait cycles). Based on the classification, some kind of confusion matrix were established. On the basis of the data included in the matrix, it was concluded that the wrong classification was most affected by the similar weight of two confused people. It was also noted, that people of the same gender and similar BH were confused most often. On the other hand, previous body injuries and dysfunctions of the motor system were the factors facilitating the recognition of people. The results obtained will allow for the design of more accurate biometric systems in the future.

Keywords

  • Human Gait Recognition
  • Ground Reaction Forces
  • Classification
access type Uneingeschränkter Zugang

Vision Analysis System for Autonomous Landing of Micro Drone

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 199 - 203

Zusammenfassung

Abstract

This article describes a concept of an autonomous landing system of UAV (Unmanned Aerial Vehicle). This type of device is equipped with the functionality of FPV observation (First Person View) and radio broadcasting of video or image data. The problem is performance of a system of autonomous drone landing in an area with dimensions of 1m × 1m, based on CCD camera coupled with an image transmission system connected to a base station. Captured images are scanned and landing marker is detected. For this purpose, image features detectors (such as SIFT, SURF or BRISK) are utilized to create a database of keypoints of the landing marker and in a new image keypoints are found using the same feature detector. In this paper results of a framework that allows detection of defined marker for the purpose of drone landing field positioning will be presented.

Keywords

  • Unmanned Aerial Vehicle
  • Micro Drone
  • Image Analysis
  • CCD Camera
  • Keypoints Descriptors
  • SIFT
  • SURF
  • BRISK
  • Object Tracking
  • Camshift
access type Uneingeschränkter Zugang

Frictional Heating During Sliding of two Semi-Spaces with Arbitrary Thermal Nonlinearity

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 204 - 208

Zusammenfassung

Abstract

Analytical and numerical solution for transient thermal problems of friction were presented for semi limited bodies made from thermosensitive materials in which coefficient of thermal conductivity and specific heat arbitrarily depend on the temperature (materials with arbitrary non-linearity). With the constant power of friction assumption and imperfect thermal contact linearization of nonlinear problems formulated initial-boundary thermal conductivity, using Kirchhoff transformation is partial. In order to complete linearization, method of successive approximations was used. On the basis of obtained solutions a numerical analysis of two friction systems in which one element is constant (cermet FMC-845) and another is variable (grey iron ChNMKh or aluminum-based composite alloy AL MMC) was conducted

Keywords

  • Frictional Heating
  • Arbitrary Thermal Non-Linearity
  • Thermosensitive Materials
access type Uneingeschränkter Zugang

Non-Uniformity of the Combustor Exit Flow Temperature in Front of the Gas Turbine

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 209 - 213

Zusammenfassung

Abstract

Various types of damages to gas-turbine components, in particular to turbine blades, may occur in the course of gas turbine operation. The paper has been intended to discuss different forms of damages to the blades due to non-uniformity of the exit flow temperature. It has been shown that the overheating of blade material and thermal fatigue are the most common reasons for these damages. The paper presents results from numerical experiments with use of the computer model of the aero jet engine designed for simulations. The model has been purposefully modified to take account of the assumed non-homogeneity of the temperature field within the working agent at the turbine intake. It turned out that such non-homogeneity substantially affects dynamic and static properties of the engine considered as an object of control since it leads to a lag of the acceleration time and to increase in fuel consumption. The summarized simulation results demonstrate that the foregoing properties of a jet engine are subject to considerable deterioration in pace with gradual increase of the assumed non-homogeneity of the temperature field. The simulations made it possible to find out that variations of the temperature field nonhomogeneity within the working agent at the turbine intake lead to huge fluctuation of the turbine rpm for the idle run.

Keywords

  • Gas Turbine
  • Blade
  • Simulation Model
  • Working Agent Temperature Field
  • Health/Maintenance Status
access type Uneingeschränkter Zugang

PID Controllers Design Applied to Positioning of Ball on the Stewart Platform

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 214 - 218

Zusammenfassung

Abstract

The paper presents the design and practical implementation of PID controllers for a Stewart platform. The platform uses a resistance touch panel as a sensor and servo motors as actuators. The complete control system stabilizing the ball on the platform is realized with the Arduino microcontroller and the Matlab/Simulink software. Two processes required to acquire measurement signals from the touch panel in two perpendicular directions X and Y, are discussed. The first process includes the calibration of the touch panel, and the second process - the filtering of measurement signals with the low pass Butterworth filter. The obtained signals are used to design the algorithm of the ball stabilization by decoupling the global system into two local subsystems. The algorithm is implemented in a soft real time system. The parameters of both PID controllers (PIDx and PIDy) are tuned by the trial-error method and implemented in the microcontroller. Finally, the complete control system is tested at the laboratory stand.

Keywords

  • PID Controller
  • Low Pass Butterworth Filter
  • Stewart-Gough Platform
  • Arduino Microcontroller
  • USB Port
  • Touch Panel Sensor
access type Uneingeschränkter Zugang

Cross-Correlation-Based Method vs. Classical Fft for Spectral Analysis of Impulse Response

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 219 - 222

Zusammenfassung

Abstract

The paper presents comparison of results of impulse response spectral analysis that has been obtained using a method based on cross-correlation with results obtained using classical FFT. The presented non-Fourier method is achieved by correlating the analyzed signal and reference single-harmonic signals and using Hilbert transform to obtain an envelope of cross-correlation. The envelope of crosscorrelation makes it possible to calculate appropriate indicator and make its plot in frequency domain as a spectrum. The spectrum obtained this way has its advantage over the FFT that the spectral resolution does not depend on duration of signal. At the same time, the spectral resolution can be much greater than spectral resolution resultant from FFT. Obtained results show that presented non-Fourier method gives frequency readout more accurate in comparison to FFT when the impulse response is a short-time signal e.g. few dozen of miliseconds lasting.

Keywords

  • Spectral Analysis
  • FFT
  • Cross-Correlation
  • Hilbert transform
  • Envelope
  • Spectral Resolution
10 Artikel
access type Uneingeschränkter Zugang

Diagnosis of Discrete-Time Singularly Perturbed Systems Based on Slow Subsystem

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 175 - 180

Zusammenfassung

Abstract

This paper deals with the diagnosis of discrete-time singularly perturbed systems presenting two time scales property. Parity space method is considered to generate the fault detection residual. The focus is in two directions. First, we discuss the residual illconditioning caused by the singular perturbation parameter. Then, the use of the slow subsystem is considered to make the fault diagnosis easier. It is shown that the designed diagnostic algorithm based on reduced order model is close to the one synthesized using the full order system. The developed approach aims at reducing the computational load and the ill-conditioning for stiff residual generation problem. Two examples of application are used to demonstrate the efficiency of the proposed method.

Keywords

  • Discrete-Time Singularly Perturbed System
  • Two Time Scales Property
  • Model Based Fault Diagnosis
  • Parity Space Approach
  • Slow Subsystem
access type Uneingeschränkter Zugang

The Impact of the FLC Controller’s Settings on the Precision of the Positioning of a Payload Transferred by a Mobile Crane

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 181 - 184

Zusammenfassung

Abstract

The paper presents a model of a control system of the slewing motion of a mobile crane in which the FLC controller was used, and then selected results of the numerical simulations of this model were presented. The influence of this controller’s settings on the precision with which the payload is positioned after it has been transferred to a target point for different angles of rotation of the jib, different lengths of the rope and different input signals of the controller was investigated.

Keywords

  • Mobile Crane
  • FLC Controller
access type Uneingeschränkter Zugang

Numerical Analysis of Temperature Field in a Disc Brake at Different Cover Angle of the Pad

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 185 - 188

Zusammenfassung

Abstract

In the paper an influence of the cover angle of the pad on temperature fields of the components of the disc brake is studied. A three-dimensional finite element (FE) model of the pad-disc system was developed at the condition of equal temperatures on the contacting surfaces. Calculations were carried out for a single braking process at constant deceleration assuming that the contact pressure corresponds with the cover angle of the pad so that the moment of friction is equal in each case analysed. Evolutions and distributions of temperature both for the contact surface of the pad and the disc were computed and shown.

Keywords

  • Temperature
  • Disc Brake
  • Cover Angle Of The Pad
  • Finite Element Method
access type Uneingeschränkter Zugang

The Impact of the Support System’s Kinematic Structure on Selected Kinematic and Dynamic Quantities of an Experimental Crane

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 189 - 193

Zusammenfassung

Abstract

This paper presents a comparative analysis of two kinematic structures of the support system (with supports with bilateral and unilateral constraints), which were used in an experimental model of a crane. The computational model was developed by using the ADAMS software. The impact of the kinematic structure of the support system on selected kinematic and dynamic values that were recorded during the slewing motion was analysed. It was found, among other things, that an increased number of degrees of freedom of the support system leads to multiple distortions of time characteristics of kinematic and dynamic quantities.

Keywords

  • Experimental Crane
  • Multi-Body Systems
  • Supports
  • Unilateral Constraints
  • Bilateral Constraints
access type Uneingeschränkter Zugang

Examination of the Effect of Psychophysical Factors on the Quality of Human Gait Recognition

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 194 - 198

Zusammenfassung

Abstract

The paper presents an analysis concerning the influence of selected psychophysical parameters on the quality of human gait recognition. The following factors have been taken into account: body height (BH), body weight (BW), the emotional condition of the respondent, the physical condition of the respondent, previous injuries or dysfunctions of the locomotive system. The study was based on data measuring the ground reaction forces (GRF) among 179 participants (3 315 gait cycles). Based on the classification, some kind of confusion matrix were established. On the basis of the data included in the matrix, it was concluded that the wrong classification was most affected by the similar weight of two confused people. It was also noted, that people of the same gender and similar BH were confused most often. On the other hand, previous body injuries and dysfunctions of the motor system were the factors facilitating the recognition of people. The results obtained will allow for the design of more accurate biometric systems in the future.

Keywords

  • Human Gait Recognition
  • Ground Reaction Forces
  • Classification
access type Uneingeschränkter Zugang

Vision Analysis System for Autonomous Landing of Micro Drone

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 199 - 203

Zusammenfassung

Abstract

This article describes a concept of an autonomous landing system of UAV (Unmanned Aerial Vehicle). This type of device is equipped with the functionality of FPV observation (First Person View) and radio broadcasting of video or image data. The problem is performance of a system of autonomous drone landing in an area with dimensions of 1m × 1m, based on CCD camera coupled with an image transmission system connected to a base station. Captured images are scanned and landing marker is detected. For this purpose, image features detectors (such as SIFT, SURF or BRISK) are utilized to create a database of keypoints of the landing marker and in a new image keypoints are found using the same feature detector. In this paper results of a framework that allows detection of defined marker for the purpose of drone landing field positioning will be presented.

Keywords

  • Unmanned Aerial Vehicle
  • Micro Drone
  • Image Analysis
  • CCD Camera
  • Keypoints Descriptors
  • SIFT
  • SURF
  • BRISK
  • Object Tracking
  • Camshift
access type Uneingeschränkter Zugang

Frictional Heating During Sliding of two Semi-Spaces with Arbitrary Thermal Nonlinearity

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 204 - 208

Zusammenfassung

Abstract

Analytical and numerical solution for transient thermal problems of friction were presented for semi limited bodies made from thermosensitive materials in which coefficient of thermal conductivity and specific heat arbitrarily depend on the temperature (materials with arbitrary non-linearity). With the constant power of friction assumption and imperfect thermal contact linearization of nonlinear problems formulated initial-boundary thermal conductivity, using Kirchhoff transformation is partial. In order to complete linearization, method of successive approximations was used. On the basis of obtained solutions a numerical analysis of two friction systems in which one element is constant (cermet FMC-845) and another is variable (grey iron ChNMKh or aluminum-based composite alloy AL MMC) was conducted

Keywords

  • Frictional Heating
  • Arbitrary Thermal Non-Linearity
  • Thermosensitive Materials
access type Uneingeschränkter Zugang

Non-Uniformity of the Combustor Exit Flow Temperature in Front of the Gas Turbine

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 209 - 213

Zusammenfassung

Abstract

Various types of damages to gas-turbine components, in particular to turbine blades, may occur in the course of gas turbine operation. The paper has been intended to discuss different forms of damages to the blades due to non-uniformity of the exit flow temperature. It has been shown that the overheating of blade material and thermal fatigue are the most common reasons for these damages. The paper presents results from numerical experiments with use of the computer model of the aero jet engine designed for simulations. The model has been purposefully modified to take account of the assumed non-homogeneity of the temperature field within the working agent at the turbine intake. It turned out that such non-homogeneity substantially affects dynamic and static properties of the engine considered as an object of control since it leads to a lag of the acceleration time and to increase in fuel consumption. The summarized simulation results demonstrate that the foregoing properties of a jet engine are subject to considerable deterioration in pace with gradual increase of the assumed non-homogeneity of the temperature field. The simulations made it possible to find out that variations of the temperature field nonhomogeneity within the working agent at the turbine intake lead to huge fluctuation of the turbine rpm for the idle run.

Keywords

  • Gas Turbine
  • Blade
  • Simulation Model
  • Working Agent Temperature Field
  • Health/Maintenance Status
access type Uneingeschränkter Zugang

PID Controllers Design Applied to Positioning of Ball on the Stewart Platform

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 214 - 218

Zusammenfassung

Abstract

The paper presents the design and practical implementation of PID controllers for a Stewart platform. The platform uses a resistance touch panel as a sensor and servo motors as actuators. The complete control system stabilizing the ball on the platform is realized with the Arduino microcontroller and the Matlab/Simulink software. Two processes required to acquire measurement signals from the touch panel in two perpendicular directions X and Y, are discussed. The first process includes the calibration of the touch panel, and the second process - the filtering of measurement signals with the low pass Butterworth filter. The obtained signals are used to design the algorithm of the ball stabilization by decoupling the global system into two local subsystems. The algorithm is implemented in a soft real time system. The parameters of both PID controllers (PIDx and PIDy) are tuned by the trial-error method and implemented in the microcontroller. Finally, the complete control system is tested at the laboratory stand.

Keywords

  • PID Controller
  • Low Pass Butterworth Filter
  • Stewart-Gough Platform
  • Arduino Microcontroller
  • USB Port
  • Touch Panel Sensor
access type Uneingeschränkter Zugang

Cross-Correlation-Based Method vs. Classical Fft for Spectral Analysis of Impulse Response

Online veröffentlicht: 27 Jan 2015
Seitenbereich: 219 - 222

Zusammenfassung

Abstract

The paper presents comparison of results of impulse response spectral analysis that has been obtained using a method based on cross-correlation with results obtained using classical FFT. The presented non-Fourier method is achieved by correlating the analyzed signal and reference single-harmonic signals and using Hilbert transform to obtain an envelope of cross-correlation. The envelope of crosscorrelation makes it possible to calculate appropriate indicator and make its plot in frequency domain as a spectrum. The spectrum obtained this way has its advantage over the FFT that the spectral resolution does not depend on duration of signal. At the same time, the spectral resolution can be much greater than spectral resolution resultant from FFT. Obtained results show that presented non-Fourier method gives frequency readout more accurate in comparison to FFT when the impulse response is a short-time signal e.g. few dozen of miliseconds lasting.

Keywords

  • Spectral Analysis
  • FFT
  • Cross-Correlation
  • Hilbert transform
  • Envelope
  • Spectral Resolution

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