2014 - Repozytorium publikacji - Politechnika Gdańska

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Publikacje z roku 2014

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Experimental Determination of Limit Adhesive Shear Strtess between Solid Wall and Liquid
- Jerzy Sawicki
2014 Pełny tekst Archives of Hydro-Engineering and Environmental Mechanics
Theoretically slip of a fluid with respect to the solid wall should occur even at a very low velocity of motion. However theoretical analysisand some empirical data suggest that there must be a limit value of shear stress, below which the slip does not appear. A simple metyhod of this stress determination was proposed in the paper.
Experimental economics in business education: Using simple games to achieve multifaceted effects
- Krzysztof Zięba
2014
Economics differs from other sciences not only because of its normative part, but also because of very limited use of experiments. In this way, economics is often perceived as being methodologically more similar to astronomy or meteorology rather than physics or chemistry. Over last decades, however, experimental economics has been significantly developed. This chapter presents some of the possibilities for academic teachers to use experiment based classroom games in business education. Firstly, general benefits from using such games are discussed. Secondly, two games are described: Pit Market Game (PMG) and Market Entry Game (MEG). The descriptions are accompanied by possible variations and modifications that can be used to achieve additional goals. A small section is dedicated to some more scientific uses of experiment- based classroom games. In the concluding part the concepts that can be addressed in both games are listed. While PMG is an essential game for introductory courses in economics, MEG simulation, as being more versatile, is recommended also for courses in management and entrepreneurship.
Experimental investigations on concrete beams reinforced with CFRP lamellas
- Piotr Korzeniowski
- Marcin Abramski
- Marek Wesołowski
2014 Pełny tekst
Paper presents experimental investigation made on two concrete beams reinforced with internal Carbon Fibre Reinforced Polymer (CFRP) lamellas (i.e. strips, bands). The reinforcement geometrical arrangement was similar as in normal concrete beams reinforced with steel bars and stirrups. The beams were destroyed by the shear forces, as intended. Obtained load-carrying capacities were lower as expected: below 40% of a calculated value. The reason of the untimely fracture was insufficient strength of connections between the vertical and longitudinal lamellas.
Experimental investigations on pressure drop during the condensation in flow of HFE7000 in vertical minichannel
- Dariusz Mikielewicz
- Michał Klugmann
- Rafał Andrzejczyk
- Jan Wajs
2014
In the work presented in the paper authors focused attention on the issues of flow resistance and pressure drop during condensation in the flow. The case of the descending flow through a cylindrical single-channel of 2.3 mm inner diameter was carefully analyzed. In the course of investigations a new working fluid HFE 7000 has been scrutinised which has a strongly differing properties in comparison to the other fluids that are commonly used for studies in the minichannels. The results of calculations have been compared with the in-house developed model for two-phase flow pressure drop with inclusion of non-adiabatic effects. The results of comparisons show satisfactory agreement.
EXPERIMENTAL STUDY OF A TEMPORARY STEEL GRANDSTAND UNDER CROWD LOAD
- Natalia Lasowicz
- Robert Jankowski
2014
Temporary structures, such as grandstands, are commonly used during different types of mass events, especially sport and music concerts. In this paper, the results of the experimental study on temporary steel grandstand are presented. The aim of the investigation was to determine modal characteristics of such structures. Modes of free vibrations and corresponding natural frequencies have been obtained for empty and occupied grandstand. The results of the study confirm that crowd provides additional mass that has a significant influence on the structure and leads to a substantial reduction in values of natural frequencies.
Experimental Study of Silent Sonar
- Jacek Marszal
2014 Pełny tekst Archives of Acoustics
Stealth is a frequent requirement in military applications and involves the use of devices whose signals are difficult to intercept or identify by the enemy. The silent sonar concept was studied and developed at the Department of Marine Electronic Systems of the Gdansk University of Technology. The work included a detailed theoretical analysis, computer simulations and some experimental research. The results of the theoretical analysis and computer simulation suggested that target detection and positioning accuracy deteriorate as the speed of the target increases, a consequence of the Doppler effect. As a result, more research and measurements had to be conducted to verify the initial findings. To ensure that the results can be compared with those from the experimental silent sonar model, the target’s actual position and speed had to be precisely controlled. The article presents the measurement results of a silent sonar model looking at its detection, range resolution and problems of incorrect positioning of moving targets as a consequence of the Doppler effect. The results were compared with those from the theoretical studies and computer simulations.
Experimental study on effectiveness of polymer dampers in reduction of structural vibrations
- Natalia Lasowicz
- Arkadiusz Kwiecień
- Bogusław Zając
- Robert Jankowski
2014
Vibrations of civil engineering structures, generated by dynamic loads, may be very dangerous to the structures themselves as well as may have significant influence on human perception and comfort. A number of different methods have been proposed in order to minimize such situations. This concern newly designed structures as well as those which dynamic properties have to be modified due to problems with excessive vibrations. One of the methods is to increase stiffness of the structure so as to avoid resonance with the excitation. Another approach assumes installation of additional dampers so as to increase dissipation of energy during vibrations. In this paper, an idea of using polymer dampers, in the form of tapes, is proposed. An experimental study on aluminum cantilevered beam has been conducted. Two different models have been considered and analyzed. One of them presents a plain cantilevered beam, while the second one considers beam with the polymer tape attached. The behavior of both models under different loads has been investigated. Two cases have been analyzed and damping ratios have been identified. The results of the study clearly show that the response of the beam with and without polymer damper is substantially different. They indicate that the application of the polymer tape may lead to even five times higher values of damping ratio. Therefore, the method can be considered as an effective one in reduction of structural vibrations.
Experimental study on the effectiveness of polymer dampers in reduction of structural vibrations
- Natalia Lasowicz
- Arkadiusz Kwiecień
- Bogusław Zając
- Robert Jankowski
2014
Vibrations of civil engineering structures, generated by dynamic loads, may be very dangerous to the structures themselves as well as may have significant influence on human perception and comfort. A number of different methods have been proposed in order to minimize such situations. This concern newly designed structures as well as those which dynamic properties have to be modified due to problems with excessive vibrations. One of the methods is to increase stiffness of the structure so as to avoid resonance with the excitation. Another approach assumes installation of additional dampers so as to increase dissipation of energy during vibrations. In this paper, an idea of using polymer dampers, in the form of tapes, is proposed. An experimental study on aluminum cantilevered beam has been conducted. Two different models have been considered and analyzed. One of them presents a plain cantilevered beam, while the second one considers beam with the polymer tape attached. The behavior of both models under different loads has been investigated. Two cases have been analyzed and damping ratios have been identified. The results of the study clearly show that the response of the beam with and without polymer damper is substantially different. They indicate that the application of the polymer tape may lead to even five times higher values of damping ratio. Therefore, the method can be considered as an effective one in reduction of structural vibrations.
Experimental tests of reinforced concrete deep-beams
- Krystyna Nagrodzka-Godycka
- Anna Kopańska
- Kamila Zmuda-Baszczyn
2014
The paper presents results of experimental research of the reinforced concrete deep beam with a spatial arrangement. Tested structural elements consist of the cantilever deep beam loaded on the height and transverse deep beam with hanging on it another one. The analysis includes crack morphology, effort of steel and load distribution. The article verified effectiveness of two different kind of reinforcement in both tested deep beams in relation to provisions which are recommended in the literature.
Experimental Tests Of Sandwich Beams In The Design Process Of GFRP Shell Footbridge Structure
- Jacek Chróścielewski
- Łukasz Pyrzowski
- Roman Romanowski
- Magdalena Rucka
2014
The paper includes selected aspects of the study to elaborate architectural, material and construction design of pedestrian footbridge spans made of composite materials. The considered footbridge is a sandwich-type shell structure. The cooperation of PET foam core with outer lining surfaces is crucial for its load bearing capacity. The paper is aimed to experimental investigation of sandwich beams subjected to bending loading. The experiments were concentrated on the effect of the foam core density and its influence on obtained results of stiffness and failure modes. The test samples were made of three different foam density cores and were subjected to four-point and three-point bending tests.
Experimental Verification of Storm Sewer Transient Flow Simulation
- Michał Szydłowski
2014 Pełny tekst Archives of Hydro-Engineering and Environmental Mechanics
The paper focuses mainly on laboratory investigations of transient and transcritical flow in a single pipe of a sewer system. The aim of this paper is to present a comparison between pressure values calculated by an improved McCormack scheme and those measured at the hydraulic laboratory of the Gdansk University of Technology, which were observed inside a pipe in an experiment for water flow with pressurization. The analysis proves that the numerical approach applied to flow simulation is a sufficiently accurate and reliable technique for predicting the basic parameters of storm sewer flow.
Experiments and FE analyses on airborne sound properties of composite structural insulated panels
- Adam Wawrzynowicz
- Marek Krzaczek
- Andrzej Tejchman-Konarzewski
2014 Pełny tekst Archives of Acoustics
Artykuł przedstawia wyniki doświadczalne i numeryczne odnośnie właściwości akustycznych paneli budowlanych. Jako panele zastosowano płyty kompozytowe konstrukcyjno-izolacyjne CSIP. Obliczenia numeryczne wykonano MES stosując podejście zaproponowane w pakiecie ABAQUS. Wyniki MES porównano bezpośrednio z doświadczeniami. Zaproponowano różne spsoby poprawy właściwości akustycznych paneli.
Explanation of Reduction of Pressure Forces in Turbine Chamber Seals
- Krzysztof Kosowski
- Robert Stępień
2014 Advances in Vibration Engineering
The paper describes a chamber seal reducing the aerodynamic forces created in shroud seals. Asymmetrical pressure distribution (due to rotor-stator eccentricity) in the blade tip clearance leads to the creation of pressure forces acting on the blade shroud. By increasing the volume above the shroud, the pressure distribution becomes more uniform on the whole shroud circumference and the effect of rotor eccentricity is reduced. It can be easily performed by introducing an extra chamber to the typical turbine blade seals. The circumferential flows in the chamber result in the decrease in the pressure differences and finally in the decrease in aerodynamic forces acting on the whole turbine rotor. A great deal of experimental and numerical research has been carried out to achieve a better explanation of the flow phenomenon and principle of operation of the chamber seals for different types of blade shrouds. The results with the appropriate comments and explanations are presented in the paper. The investigations were carried out for different types of shrouds, various shapes and dimensions of the chambers, and for different turbine working conditions. The proposed chamber seal can remarkably reduce aerodynamic forces generated in the labyrinth type shroud seals, sometimes even by more than 60%.
Explicit and implicit difefrence methods for quasilinear first order partial functional differential equations.
- Zdzisław Kamont
- Anna Szafrańska
2014 Computational Methods in Applied Mathematics
Initial boundary value problems of the Dirichlet type for quasilinear functional differential equations are considered. Explicit difference schemes of the Euler type and implicit difference methods are investigated. Suffcient conditions for the convergence of approximate solutions are given and comparisons of the methods are presented. It is proved that assumptions on the regularity of given functions are the same for both classes of the methods. It is shown that conditions on the mesh for explicit dierence schemes are more restrictive than suitable assumptions for implicit methods. Error estimates for both the methods are presented. Interpolating operator corresponding to functional variables is constructed.
Exploring universities' efficiency differentials between countries in a multi-year perspective: an application of bootstrap DEA and Malmquist index to Italy and Poland, 2001-2011
- Tommaso Agasisti
- Joanna Wolszczak-Derlacz
2014
This study employs data envelopment analysis (DEA) to evaluate relative efficiency of a sample of 54 Italian and 30 Polish public universities for the period between 2001 and 2011. The examination is conducted in two steps: first unbiased DEA efficiency scores are estimated and then are regressed on external variables to quantitatively asses the direction and magnitude of the impact of potential determinants. The analysis shows the strong heterogeneity in the efficiency scores within each country, more pronounced than the difference in average efficiency scores between countries. There is evidence that efficiency is determined by revenues’ and academic staff’s structure: competitive versus non-competitive resources, and the number of professors among academic staff. The study also explores the variation of efficiency and productivity over time, and reveals that while pure efficiency change was similar between the two countries, the efficiency frontier improved more in Italy than in Poland.
Extraction of antenna pattern from near field antenna measurements distorted by undesired emission
- Mateusz Mazur
- Wojciech Marynowski
- Adam Kusiek
- Włodzimierz Zieniutycz
2014
In this paper authors present experimental correction of antenna pattern obtained from near field measurements when they are distorted by determined electromagnetic emission. Such situation may be met e.g. when feeding or supply subsystem interacts with antenna radiation pattern due to self-emission. Presented results of experiments show effectiveness of extraction of antenna pattern utilizing near field antenna measurements.
Eye-Gaze Tracking-Based Telepresence System for Videoconferencing
- Bartosz Kunka
- Adam Korzeniewski
- Bożena Kostek
- Andrzej Czyżewski
2014
An approach to the teleimmersive videoconferencing system enhanced by the pan-tilt-zoom (PTZ) camera, controlled by the eye-gaze tracking system, is presented in this paper. An overview of the existing telepresence systems, especially dedicated to videoconferencing is included. The presented approach is based on the CyberEye eye-gaze tracking system engineered at the Multimedia Systems Department (MSD) of Gdańsk University of Technology (GUT), as well as on a standard PTZ security camera communicating with the computer by the TCP/IP protocol. Technical aspects of the developed system prototype including two different use cases (one-way and two-way configuration of system) are described. Moreover, a discussion related to the gathered user’s experience as well as to difficulties and opportunities concerning the proposed approach are included.
Facial data registration facility for biometric protection of electronic documents
- Maciej Maroszczyk
- Marcin Pilecki
- Marcin Szczypka
2014
In modern world, information is crucial, and its leakage may lead to serious losses. Documents as the main medium of information must be therefore highly protected. Nowadays, the most common way of protecting data is using passwords, however it seems inconvenient to type complex passwords, when it is needed many times a day. For that reason a significant research has been conducted on biometric authentication as an alternative to passwords. While there is a wide selection of device biometric protection methods and tools (like face logon plugins to Windows [KL]),lightweight biometric encryption of digital documents has not been deeply investigated yet.
Factory Acceptance Test – Strain Gauge Measurement - Report no: WOiO /II/88/2014
- Jakub Kowalski
- Janusz Kozak
- Marek Kula
2014
Tested object was 40 meters long jib and its foundation, placed in Gdansk Shiprepair Yard, manufactured by KMK. The contruction was dedicated to the passenger cruise vessel "North Star" The Strain Gauge measurement in different location and load situation was done in order to validate calculation finite element models used during strength analysis for project. The expertise contains: methodology of the measurements, description of used data acquisition system, results as a time dependent stress graphs and conclusions
Factory Acceptance Test – Strain Gauge Measurement, Report no: WOiO /II/123/2014
- Jakub Kowalski
- Janusz Kozak
- Marek Kula
2014
Tested object was 40 meters long jib and its foundation, placed in Gdansk Shiprepair Yard, manufactured by KMK. The contruction was dedicated to the passenger cruise vessel "Quantum of the Seas" The Strain Gauge measurement in different location and load situation was done in order to validate calculation finite element models used during strength analysis for project. The expertise contains: methodology of the measurements, description of used data acquisition system, results as a time dependent stress graphs and conclusions