2017 - Repozytorium publikacji - Politechnika Gdańska

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Publikacje z roku 2017

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Improvement of radiotracers experiments in mass transfer processes
- Leszek Petryka
- Volodymyr Mosorov
- Marcin Zych
- Robert Hanus
- Jerzy Sobota
- Marek Jaszczur
- Dariusz Świsulski
2017 EPJ Web of Conferences
The greatest part of industrial mass transfer is based on continuous transportation of different substances throughout especially constructed installations. In that kind of practice, a flow of such mass in each part determines the process unit and can be described by the residence time distribution (RTD) of the substance inside this unit. This parameter may be evaluated by the properly arranged tracer experiment. It is worthwhile to notice that flow components are labeling for a sufficiently long time for offering a lot of advanced techniques fitted to the particular circumstances.
Improvement of the thrust bearing calculation considering the convectional heating within the space between the pads
- Monika Chmielowiec-Jabłczyk
- Andreas Schubert
- Christian Kraft
- Hubert Schwarze
- Michał Wodtke
- Michał Wasilczuk
2017
A modern thrust bearing calculation tool should consider not only the oil film between pad and rotating collar but also the space between the pads. The oil flow in the space has a significant influence on the oil film inlet temperature, the convectional cooling of pad and collar and should be included in the bearing calculation methods. The authors use a tool developed at Clausthal University of Technology in cooperation with the research association for combustion engines (FVV) eV in Germany. The solutions of the Reynolds equation, the energy equation and the heat transfer equation are done iteratively using the Finite Volume Method by considering constant flow rate. Between many features of the tool one can mention for the oil film: JFO cavitation model, laminar/turbulent flow and centrifugal force. This paper shows investigations done for tilting pad thrust bearings that are used in hydro-generating machines. The calculation results are compared with measurements done on a thrust bearing test rig at Gdansk University of Technology. The pad number of the original test rig (8) with an outer diameter of 180 mm was changed to 4, 6 and 9 of the same size. The influence of the distance between the pads is studied for loads up to 3 MPa, speeds up to 4000 rpm and different oil flows. Central and offset pad supports are tested. The calculated pad temperature field is adjusted to the measured values using different heat convection coefficients. After validation of the calculation tool the results of other conditions like high transient load are shown.
Improving sensitivity of residual current transformers to high frequency earth fault currents
- Stanisław Czapp
- Krzysztof Dobrzyński
- Jacek Klucznik
- Zbigniew Lubośny
- Robert Kowalak
2017 Pełny tekst Archives of Electrical Engineering
For protection against electric shock in low voltage systems residual current devices are commonly used. However, their proper operation can be interfered when high frequency earth fault current occurs. Serious hazard of electrocution exists then. In order to detect such a current, it is necessary to modify parameters of residual current devices, especially the operating point of their current transformer. The authors proposed the modification in the structure of residual current devices. This modification improves sensitivity of residual current devices when high frequency earth fault current occurs. The test of the modified residual current device proved that the authors’ proposition is appropriate.
Improving Thermal Insulation Properties for Prefabricated Wall Components Made of Lightweight Aggregate Concrete with Open Structure
- Marcin Abramski
2017 Pełny tekst
Porous concrete is commonly used in civil engineering due to its good thermal insulation properties in comparison with normal concrete and high compression strength in comparison with other building materials. An extremely porous concrete, called ‘lightweight aggregate concrete with open structure’ (LAC), is used in some German plants to produce prefabricated wall components. They are used mainly in hall buildings, e.g. supermarkets. The need of improving thermal insulation properties was an inspiration to realise a project described in the paper. Its aim was to reduce the heat transfer coefficient for the wall components. Three different wall structure types were designed and compared in full-scale laboratory tests with originally produced wall components in terms of load-carrying capacity and stiffness. The load was applied perpendicularly to the wall plane. As the components are not originally used for load-bearing walls, but for curtain walls only, the wind load is the main load for them. The wall components were tested in horizontal position and the load was applied vertically. Totally twelve wall components 8.00 x 2.00 x 0.25m (three for every series) were produced in the prefabrication plant and tested in the University of Kaiserslautern laboratory. The designed and tested components differed from each other in the amount of expanded polystyrene (EPS), which was placed in the plant inside the wall structure. The minimal amount of it was designed in the original wall component type. Besides, two improved types of prefabricated wall had built-in steel lattice girders. The failure mode was the same for all the tested components: diagonal cracks occurred on the sides of each component due to their insufficient shear-force-capacity. Load-carrying capacities obtained in the tests were for all wall structure types similar and much higher (many times) than internal forces (i.e. bending moments and shear forces) calculated for a wind load acting on a typical hall building according to the German codes. An increased amount of EPS (up to 30 per cent in volume) did not influence significantly the wall structural strength. The use of the steel lattice girders caused some technological problems and led to a quality loss of the produced components. The future use of the lattice girders would require a change in the production process: it would have to be more labour consuming.
In vitro affinity of Deinococcus radiodurans MutS towards mismatched DNA exceeds that of its orthologues from Escherichia coli and Thermus thermophilus
- Michał Banasik
- Anna Stanisławska-Sachadyn
- Ewa Hildebrandt
- Paweł Sachadyn
2017 Pełny tekst JOURNAL OF BIOTECHNOLOGY
The mismatch binding protein MutS is responsible for the recognition of mispaired and unpaired bases, which is the initial step in DNA repair. Among the MutS proteins most extensively studied in vitro are those derived from Thermus thermophilus, Thermus aquaticus and Escherichia coli. Here, we present the first report on the in vitro examination of DNA mismatch binding activity of MutS protein from Deinococcus radiodurans and confront this with the properties of those from E. coli and T. thermophilus. The analyses which included mobility gel-shift assay, colorimetric and qPCR estimation of MutS-bound DNA clearly showed that D. radiodurans MutS exhibited much higher affinity towards mismatched DNA in vitro than its counterparts from E. coli and T. thermophilus. In addition, D. radiodurans MutS displayed a significantly higher specificity of DNA mismatch binding than the two other orthologues. The specificity expressed as the ratio of mismatched to fully complementary DNA bound reached over 4 and 20-fold higher values for D. radiodurans than for T. thermophilus and E. coli MutS, respectively. The results demonstrate mainly the biotechnological potential of D. radiodurans MutS but the in vitro characteristics of the MutS orthologues could reflect substantial differences in DNA mismatch binding activities existing in vivo.
Increased inspiratory resistance affects the dynamic relationship between blood pressure changes and subarachnoid space width oscillations
- Magdalena Wszedybyl-Winklewska
- Jacek Wolf
- Ewa Swierblewska
- Katarzyna Kunicka
- Kamila Mazur
- Marcin Gruszecki
- Pawel Winklewski
- Andrzej F. Frydrychowski
- Leszek Bieniaszewski
- Krzysztof Narkiewicz
- Krzysztof Narkiewicz
2017 Pełny tekst PLOS ONE
Background and objective Respiration is known to affect cerebrospinal fluid (CSF) movement. We hypothesised that increased inspiratory resistance would affect the dynamic relationship between blood pressure (BP) changes and subarachnoid space width (SAS) oscillations. Methods Experiments were performed in a group of 20 healthy volunteers undergoing controlled intermittent Mueller Manoeuvres (the key characteristic of the procedure is that a studied person is subjected to a controlled, increased inspiratory resistance which results in marked potentiation of the intrathoracic negative pressure). BP and heart rate (HR) were measured using continuous finger-pulse photoplethysmography; oxyhaemoglobin saturation with an ear-clip sensor; end-tidal CO2 with a gas analyser; cerebral blood flow velocity (CBFV), pulsatility and resistive indices with Doppler ultrasound. Changes in SAS were recorded with a new method i.e. near-infrared transillumination/backscattering sounding. Wavelet transform analysis was used to assess the BP and SAS oscillations coupling. Results Initiating Mueller manoeuvres evoked cardiac SAS component decline (-17.8%, P<0.001), systolic BP, diastolic BP and HR increase (+6.3%, P<0.001; 6.7%, P<0.001 and +2.3%, P<0.05, respectively). By the end of Mueller manoeuvres, cardiac SAS component and HR did not change (+2.3% and 0.0%, respectively; both not statistically significant), but systolic and diastolic BP was elevated (+12.6% and +8.9%, respectively; both P<0.001). With reference to baseline values there was an evident decrease in wavelet coherence between BP and SAS oscillations at cardiac frequency in the first half of the Mueller manoeuvres (-32.3%, P<0.05 for left hemisphere and -46.0%, P<0.01 for right hemisphere) which was followed by subsequent normalization at end of the procedure (+3.1% for left hemisphere and +23.1% for right hemisphere; both not statistically significant). Conclusions Increased inspiratory resistance is associated with swings in the cardiac contribution to the dynamic relationship between BP and SAS oscillations. Impaired cardiac performance reported in Mueller manoeuvres may influence the pattern of cerebrospinal fluid pulsatility.
Individual Resources and Intercultural Interactions
- Beata Basińska
2017
The work environment in multinational corporations (MNCs) is specific and demanding including intercultural interactions with co-workers and clients and using a foreign language. Some individual resources can help in dealing with these circumstances. Individual resources refer to personal dispositions, competencies and prior experiences. With regard to previous studies, a caravan of personal resources, namely Psychological Capital (Luthans et al., Pers Psychol 60 (3): 541–572, 2007), can reveal the source of inconsistencies in results in a multicultural work setting. The aim of this study was to examine the relationships between positive psychological capital and other individual and professional resources (functional language, prior international experiences, age, and job tenure), which can help employees to deal with a demanding multinational work environment and particularly with intercultural interactions. The results of a quantitative study among a Polish group of employees in MNCs have demonstrated that psychological capital was slightly correlated with their international experience and moderately correlated with proficiency in a foreign language used in the corporation as a functional language. The psychological capital of the respondents was not correlated with age, but was slightly correlated with their job tenure. The differences between the two subgroups depended on the job position, indicating that the supervisors had a higher level of psychological capital than employees (large effect size) as well as having a higher level of resilience, hope and optimism (moderate effect sizes). Including some shortcomings of the study, the association between positive psychological capital and other individual resources was discussed and some practical implications were also indicated. The research suggests that organizations can reap benefits from the individual resources of employees and can play an active role in the development of psychological capital. Thus, they may create their competitive advantage on the labour market.
Indoor air quality in public utility environments-a review
- Monika Śmiełowska
- Mariusz Marć
- Bożena Zabiegała
2017 Pełny tekst ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
Indoor air quality has been the object of interest for scientists and specialists from the fields of science such as chemistry, medicine and ventilation system design. This results from a considerable number of potential factors, which may influence the quality of the broadly understood indoor air in a negative way. Poor quality of indoor air in various types of public utility buildings may significantly affect an increase in the incidence of various types of civilisation diseases. This paper presents information about a broad spectrum of chemical compounds that were identified and determined in the indoor environment of various types of public utility rooms such as churches, museums, libraries, temples and hospitals. An analysis of literature data allowed for identification of the most important transport paths of chemical compounds that significantly influence the quality of the indoor environment and thus the comfort of living and the health of persons staying in it.
Induction machine behavioral modeling for prediction of EMI propagation.
- Marek Turzyński
2017 Pełny tekst Bulletin of the Polish Academy of Sciences-Technical Sciences
This paper presents the results of wideband behavioral modeling of an induction machine (IM). The proposed solution enables modeling the IM differential- and common-mode impedance for a frequency range from 1 kHz to 10 MHz. Methods of parameter extraction are derived from the measured IM impedances. The developed models of 1.5 kW and 7.5 kW induction machines are designed using the Saber Sketch scheme editor and simulated in the SABER simulator. Modeling validation is based on prediction of electromagnetic interference (EMI) emissions of common-mode and differential-mode current spectra of experimental inverter-fed IM drives.
Induction motor bearings diagnostic indicators based on MCSA and normalized triple covariance
- Tomasz Ciszewski
2017 Pełny tekst
Induction motors are one of the most widely used electrical machines. Statistics of bearing failures of induction motors indicate, that they constitute more than 40% of induction motor damage. Therefore, bearing diagnosis is so important for trouble-free work of induction motors. The most common methods of bearing diagnosis are based on vibration signal analysis. The main disadvantage of those methods is the need for physical access to the diagnosed machine, which is not always possible. Methods based on motor current signature analysis are free of this disadvantage. Preliminary studies have shown that motor current signature analysis based normalized triple covariance is a very good diagnostic indicator for induction motor bearings. This paper presents an attempt to find a more accurate diagnostic indicator based on normalized triple covariance. In this paper the author verifies how many diagnostic features (normalized triple covariances) included in diagnostic indicator can give better separation between healthy and unhealthy cases.
Inertial Sensors Applications in Underwater Measurements
- Krzysztof Bikonis
- Jerzy Demkowicz
2017 Pełny tekst HYDROACOUSTICS
Over the past decades microelectromechanical systems (MEMS) researchers have demonstrated a number of microsensors for almost every possible sensing modality, including attitudes. Current MEMS inertial measurement units (IMU) come in many shapes, sizes, and costs — depending on the application, and performance required. MEMS sensors have proved and demonstrated performance exceeding those of their macroscale counterpart sensors. In the paper chosen IMU applications in underwater measurements are presented. First, for reduction of instability of the underwater sensor during measurements, like multibeam echosounder system (MBES), where the MEMS parameters’ quality are crucial for further MBES record-processing. Second, in underwater navigation systems, for determining the position of underwater vehicles, like Remotely Operated Vehicles (ROV) and, more recently, Autonomous Underwater Vehicle (AUV) or to improve other positioning methods.
Influence of anisotropic stiffness in numerical analyses of tunneling and excavation problems in stiff soils
- Marcin Cudny
- Ewelina Partyka
2017
In the stiff overconsolidated soil deposits anisotropy influences small and intermediate strain stiffness and hence it has important impact on the results of discplacement preditcions in soil-structure modelling. The authors developed a cross-anisotropic soil model which combines both stress dependent and micro-structural anisotropy. The model is based on the anisotropic hyperelastic kernel for small strain stiffness. Reference shear modulus is subjected to the stiffness degradation function of strain controlled by the Brick-type procedure. It allows to model stiffness degradation and its regaining after loading reversals in the intermediate strain range. The shear strength is controlled, however, by the conventional isotropic criterion. The main components of the model are presented with some element simulations. Finally the model is used in two example FE-analyses of tunnelling and excavation boundary value problems. Results with different degrees of microstructural cross-anisotropy and stress induced anisotropy are compared and discussed.
Influence of electropolymerization temperature on corrosion, morphological and electrical properties of PPy doped with salicylate on iron
- Karolina Cysewska
- Maria Gazda
- Piotr Jasiński
2017 Pełny tekst SURFACE & COATINGS TECHNOLOGY
In this work, the influence of the electropolymerization temperature on corrosion, morphological and electrical properties of polypyrrole (PPy) film is studied. Polypyrrole is electrochemically synthesized on iron in the presence of sodium salicylate. The X-ray diffraction and scanning electron microscopy are performed in order to study the structure and morphology of electrodeposited PPy. The electroactive surface area, corrosion performance and resistance of the PPy film on iron are also investigated as a function of electropolymerization temperature. The results show that the synthesis temperature significantly affects the properties of the PPy film on iron. It is observed that at 25 °C amorphous PPy is formed, whereas lowering the temperature leads to the formation of a film containing crystallites of salicylic acid. The latter reveals lower corrosion protection and a much higher level of resistance compared to the amorphous one. These characteristics were associated with the presence of insulating salicylic acid crystals in the layer structure.
Influence of input data on airflow network accuracy in residential buildings with natural wind - and stack - driven ventilation.
- Krzysztof Arendt
- Marek Krzaczek
- Andrzej Tejchman-Konarzewski
2017 Building Simulation
W artykule omówiono wpływ danych wejściowych na dokładność modelu przepływu sieciowego powietrza w budynkach mieszkalnych z naturalną i kominową wentylacją. Zastosowano połączony model AFN-BES. Wyniki numeryczne omówiono dla 8 różnych przypadków z różnymi danymi ciśnienia wiatru. Wyniki pokazały, że ogromny wpływ danych wejściowych dotyczących ciśnienia wiatru na wyniki numeryczne.
Influence of Installation Effects on Pile Bearing Capacity in Cohesive Soils – Large Deformation Analysis Via Finite Element Method
- Jakub Konkol
- Lech Bałachowski
2017 Pełny tekst Studia Geotechnica et Mechanica
In this paper, the whole process of pile construction and performance during loading is modelled via large deformation finite element methods such as Coupled Eulerian Lagrangian (CEL) and Updated Lagrangian (UL). Numerical study consists of installation process, consolidation phase and following pile static load test (SLT). The Poznań site is chosen as the reference location for the numerical analysis, where series of pile SLTs have been performed in highly overconsolidated clay (OCR ≈ 12). The results of numerical analysis are compared with corresponding field tests and with so-called “wish-in-place” numerical model of pile, where no installation effects are taken into account. The advantages of using large deformation numerical analysis are presented and its application to the pile designing is shown.
Influence of operation temperature instability on gas sensor performance
- Grzegorz Jasiński
2017
Gas sensors based on the semiconducting metal-oxides, such as SnO2, have been found to be very useful for detecting a wide range of gases. The reversible interactions of the gas with the surface of the sensing layer made of semiconducting metal-oxides are responsible for changes of sensor resistance which is usually used as a measure of sensor response. Semiconductor gas sensors are commercially available and applied in numerous gas detection systems. They are reliable, small, rugged and inexpensive. However, there are a few problems limiting the wider use of such sensors. Semiconductor gas sensor usually exhibits a low selectivity, a drift and low repeatability of the response, strong influence of temperature and moisture on sensor properties. Instability of operating temperature is one of the factors that influence sensors response and should be taken into consideration during real life measurements. In this work some experimental results demonstrating how ambient temperature affects sensor operating temperature are presented. An approach to stabilize sensor temperature by controlling sensor heater voltage have been proposed. All measurement are performed with dedicated measurement stand consisting of few bench measuring instruments.
Influence of processing conditions on crystal structure of BiNbO 4 ceramics
- Agata Lisińska-Czekaj
- Dionizy Czekaj
- Julian Plewa
2017 Ciencia & Tecnologia dos Materiais
Bismuth niobate (BiNbO4) has attracted attention as a low-fired ceramics with promising microwave application potential. It belongs to the bismutocolumbite oxides with similarly to scheelite-like stibiotantalite structure (SbTaO4) A3+B5+O4. Aim of the present research was to fabricate BiNbO4 ceramics by solid state reaction route from the mixture of simple oxides viz. Bi2O3, and Nb2O5, and study its phase composition as well as crystal structure by X-ray diffraction method. The Rietveld refinement method was utilized for analysis of diffraction patterns. It was found that the mass change effects finished at temperature T=500C and the total mass change was about Δm=-0.78%. It was found that BiNbO4 ceramics sintered in ambient air exhibited multiphase composition i.e. apart from the major a-BiNbO4 phase the orthorhombic Bi5Nb3O15, Bi3Nb17O47 and cubic Bi3NbO7 phases were present. An increase in sintering temperature caused an increase in amount of major a-BiNbO4 phase which adopted an orthorhombic symmetry described well by Pnna(52) space group.
Influence of Property Division on the Technical Condition of a Building
- Emilia Miszewska
- Beata Grzyl
- Adam Kristowski
2017 Pełny tekst
In this article, the correlation between a technical condition of a building and property division is analyzed and assessed. In the course of the usage of a building, the process of its degradation and the increase in the demands of property occupants can be observed. There is a direct connection between the difficult technical condition of a building and the fragmentation of the ownership structure. Although not considered in the literature, it is noticeable in expert opinions and building inspections. Due to the above-mentioned connection, the renovations of the property are not very effective and justified from an economical point of view.
Influence of pulse waves on the transmission of near-infrared radiation in outer-head tissue layers.
- Jerzy Pluciński
- Andrzej Frydrychowski
2017 Pełny tekst Frontiers of Optoelectronics
In this study, we investigate the effect of pulse waves on the transmission of near-infrared radiation in the outer tissue layers of the human head. This effect is important in using optical radiation to monitor brain conditions based on measuring the transmission changes in the near-infrared radiation between the source and the detector, placed on the surface of the scalp. This is because the signal related to the changes in the width of the subarachnoid space (SAS) due to the pulse wave is modiﬁed. These latter changes can be used, for instance, in detecting cerebral edema and in evaluating cerebral oxygenation. The research was performed by modeling the propagation of near-infrared radiation in the tissue layers using a Monte-Carlo method. The main objective of this study was to assess the extent to which the changes in the transmission of near-infrared radiation correspond to the changes in the optical parameters of the tissues of the head and in the width of the subarachnoid layer.
Influence of the Addition of Selected Spices on Sensory Quality and Biological Activity of Honey
- Aleksandra Wilczyńska
- Joanna Newereli-Guz
- Piotr Szweda
2017 Pełny tekst JOURNAL OF FOOD QUALITY
Bee honey is nutritious and has numerous health benefits, but its taste is for many people too bland. Honey with addition of spices could be important to the food industry as a functional product with positive health image and interesting taste. Such product would definitely meet health-driven consumers’ expectations. Therefore, the aim of this study was to evaluate the effect of addition of selected spices on sensory, antimicrobial, and antioxidant properties of honey. Results showed that the addition of spices significantly affected the taste and the smell of honey () and that honey with the cinnamon was the most desired and easily accepted product by the consumers. The addition of spices had no significant effect on texture and appearance. All tested samples showed the ability to inhibit the growth of bacteria and, contrary to the assumptions, the addition of spices did not cause an increase of antimicrobial activity. The results also showed that the kind and amount of added spice significantly affected the antioxidant activity: ability to scavenge free radicals and total phenolics content. The highest antioxidant activity revealed the honey with cinnamon and the lowest revealed the honey with cardamom addition.