2018 - Repozytorium publikacji - Politechnika Gdańska

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Comparison of hydrochemistry and organic compound transport in two non-glaciated high Arctic catchments with a permafrost regime (Bellsund Fjord, Spitsbergen)
- Sara Lehmann-Konera
- Łukasz Franczak
- Waldemar Kociuba
- Danuta Szumińska
- Stanisław Chmiel
- Żaneta Polkowska
2018 Pełny tekst SCIENCE OF THE TOTAL ENVIRONMENT
An increase in air temperature related to climate change results in the retreat of glaciers, the degradation of permafrost, and the expansion of glacier-free areas in the polar regions. All these processes lead to changes in the Arctic landscape. They influence the hydrochemistry of streams and rivers fed by glaciers and thawing permafrost. In this study, we examine eighty two water samples from two non-glaciated catchments with snow-permafrost regime: the Tyvjobekken Creek and the Reindeer Creek (NW Wedel-Jarlsberg Land, Spitsbergen). We cover hydrometeorological measurements, fluctuations of physicochemical parameters (pH, specific electrolytic conductivity (SEC)), and the presence of selected organic compounds (dissolved organic carbon (DOC), formaldehyde (HCHO), ∑phenols). The obtained levels of DOC (0.061-0.569 mgC L-1) and HCHO (<LOD-0.140 mg L-1) in water samples of these two high Arctic creeks confirm the role of the melting permafrost as a rich source of terrestrial organic carbon and organic pollutants, as well as the impact of rainfall on surface water chemistry. It was found that fluctuations of physicochemical indices (pH, SEC, DOC) were related to changes in mean daily discharge of Reindeer Creek (0.012-0.034 m3 s-1) and Tyvjobekken Creek (0.011-0.015 m3 s-1) (r>0.40). The Tyvjobekken Creek catchment, in contrast to Reindeer Creek catchment, turned out to be resistant to rapid changes in meteorological conditions (r <0.10) and surface runoff. The processes of permafrost thawing, calcium carbonate dissolution, and biogeochemical “breathing” of soils proved to be crucial for the development of water chemistry. In conclusion, the surface water chemistry of the Reindeer Creek was found to result from the mutual influence of hydrometeorological indices and the biogeochemical environment of the catchment.
COMPARISON OF INVESTMENT PERFORMANCE MEASURES USING THE EXAMPLE OF SELECTED STOCK EXCHANGES
- Marcin Potrykus
2018 Pełny tekst Nauki o Finansach. Prace Naukowe Uniwersytetu Ekonomicznego we Wrocławiu
In the following paper, the main objective is to examine whether the selection of the performance measure influences the evaluation of individual investments and the performance rankings generated on that basis. This study presents the values of 16 performance indicators along with their detailed descriptions. All calculations were made using the R program, and the source code can be found at the end of the article. Nine selected stock indices were analysed during the period January 1997–December 2015, and the monthly logarithmic rates of return for these indices were calculated. For 14 out of the 16 measures analysed, it was shown that the choice of effectiveness measure had no influence on the evaluation of individual investments; therefore, it is not important whether the investor uses the Sharpe ratio or the Calmar ratio as an indicator of efficiency, since both measures are almost identical in rank for a particular investment. This has not been confirmed for the Upside Potential ratio, which means that using this indicator may lead to different investment decisions in which the objective is to maximize efficiency. Moreover, based on the analysis, it was found that the OMXC 20, DAX 30, and OMXS 30 indexes had the highest efficiency during the period January 1997–December 2015, while the AEX, WIG 20, and PSI 20 indexes were characterized with having the lowest levels of efficiency.
Comparison of Methods for Real and Imaginary Motion Classification from EEG Signals
- Piotr Szczuko
- Michał Lech
- Andrzej Czyżewski
2018
A method for feature extraction and results of classification of EEG signals obtained from performed and imagined motion are presented. A set of 615 features was obtained to serve for the recognition of type and laterality of motion using 8 different classifications approaches. A comparison of achieved classifiers accuracy is presented in the paper, and then conclusions and discussion are provided. Among applied algorithms the highest accuracy was achieved with: Rough Set, SVM and ANN methods.
Comparison of modelling and measurement results of spectra emitted by a programmable lamp
- Mateusz Feldzensztajn
- Adam Mazikowski
2018 Pełny tekst Photonics Letters of Poland
Nowadays artificial light with an optimized spectrum is used in many different applications. For instance, it is widely used in museums and exhibitions to illuminate the art. Moreover, such light stimulates the growth of plants, or can be applied in industry and healthcare. To achieve the best results for each application, the adjusting of a dedicated spectrum is required, which is a complicated task. The ongoing research is focused on simplifying this process. In this paper we present the developed lamp with a programmable spectrum, and its user interface. Predicted and measured output spectra are investigated.
COMPARISON OF NOISE EMISSION OF HCT AND CLASSIC VEHICLE COMBINATIONS FOR TIMBER TRANSPORTATION IN SWEDEN
- Ulf Sandberg
- Sogol Kharrazi
- Piotr Mioduszewski
2018
By means of a special simulation tool, the noise emission of a high-capacity heavy vehicle (11 axles) was compared to that of a classic heavy vehicle (a truck-dolly-semitrailer with 8 axles). The two cases are designated “Extended vehicle” versus “Classic vehicle” in this study, having total lengths of 34 and 25 m, respectively. The Classic vehicle represents the most common articulated heavy vehicle configuration for transport of timber and other goods in Sweden. Tyres were assumed to be typical of each axle and their noise emission values were taken from a recent study. Noise from the propulsion unit were assumed to just meet the present maximum legal levels. It was found that noise emission from the Extended vehicle is approx. 1.5 dB higher than for Classic vehicle, as max. A-weighted level per vehicle passage, but as the number of vehicles in traffic is lower for a certain transportation volume, the resulting road traffic noise exposure in terms of A-weighted equivalent level LAeq is similar. Consequently, noise emission is not a factor that gives either vehicle type a clear advantage over the other.
Comparison of noise reduction methods in radiometric correlation measurements of two-phase liquid-gas flows
- Marcin Zych
- Robert Hanus
- Barbara Wilk
- Leszek Petryka
- Dariusz Świsulski
2018 Pełny tekst MEASUREMENT
Two-phase liquid-gas flows occur frequently in the mining, energy, chemical, and petrochemical industries. One of non-contact methods used to analyse these flows is the gamma ray absorption method. However, the signals received from radiation detectors contain a significant stochastic noise, which makes them difficult to analyse. The article describes four methods of noise reduction in cross-correlation measurements of water-air mixture flows in a horizontal pipeline. In addition to the classical method of digital filtering of signals, the methods consisting in signal spectrum filtering, discrete wavelet transformation, and Nadaraya-Watson kernel estimator are described. Sample results of the measurements carried out in the horizontal pipe having the inner diameter of 30 mm for the air bubbles velocity ranging from 0.7 to 1.4 m/s are presented. In the research, the absorption set composed of two linear Am-241 gamma-ray sources and two scintillation NaI(Tl) probes was used. It was found that the lowest measurement uncertainty of the dispersed phase flow velocity is obtained when the cross-correlation distributions of the recorded signals are smoothed using the Discrete Wavelet Transform or the Nadaraya-Watson kernel estimator.
Comparison of predictive methods for flow boiling heat transfer in conventional channels and minichannels - the effect of reduced pressure
- Dariusz Mikielewicz
- Blanka Jakubowska
2018 Pełny tekst MATEC Web of Conferences
In the paper are presented the results of follow on studies from [1]–[3] using authors own model to predict heat transfer coefficient during flow boiling. The model has been tested against a large selection of experimental data collected from various researchers to investigate the sensitivity of the in-house developed model. The collected experimental data came from various studies from literature and were conducted for the full range of quality variation and a wide range of mass velocity and saturation temperatures. In the work are presented the results of calculations obtained using the in-house developed semi empirical model on selected experimental flow boiling data of the refrigerants: R134a, R1234yf, R600a, R290, NH3, CO2, R236fa, R245fa, R152a and HFE7000. In the present study the particular attention was focused on the influence of reduced pressure on the predictions of the theoretical model. The results of calculations were to test the sensitivity of the flow boiling model with respect to selection of the appropriate two-phase flow multiplier, which is one of thedistinctive elements of the in-house model. The main purpose of this paper however is to show the effect of the reduced pressure on the predictions of heat transfer during flow boiling.
COMPARISON OF PREDICTIVE METHODS FOR FLOW BOILING HEAT TRANSFER IN CONVENTIONAL CHANNELS AND MINICHANNELS – THE EFFECT OF REDUCED PRESSURE
- Dariusz Mikielewicz
- Blanka Jakubowska
2018 Pełny tekst MATEC Web of Conferences
In the paper are presented the results of follow on studies from [1]–[3] using authors own model to predict heat transfer coefficient during flow boiling. The model has been tested against a large selection of experimental data collected from various researchers to investigate the sensitivity of the in-house developed model. The collected experimental data came from various studies from literature and were conducted for the full range of quality variation and a wide range of mass velocity and saturation temperatures. In the work are presented the results of calculations obtained using the in-house developed semi empirical model on selected experimental flow boiling data of the following refrigerants: R134a, R1234yf, R600a, R290, NH 3 , CO 2 , R236fa, R245fa, R152a and HFE7000. In the case of the fluid HFE7000 authors own unpublished experimental results have also been presented. In the present study the particular attention was focused on the influence of reduced pressure on the predictions of the theoretical model. The results of calculations were to test the sensitivity of the flow boiling model with respect to selection of the appropriate two-phase flow multiplier, which is one of the distinctive elements of the in-house model. Four two-phase flow multiplier models were used for this purpose, i.e. due to Müller-Steinhagen and Heck and its in-house modification for applicability to minichannels, Friedel and Tran. The main purpose of this paper however is to show the effect of the reduced pressure on the predictions of heat transfer during flow boiling in minichannels.
Comparison of selected parametric methods for prediction of inland waterways ship hull resistance in towing tank test
- Artur Karczewski
- Janusz Kozak
2018 Pełny tekst Polish Maritime Research
In the paper selected approximate methods for calculation of inland waterways ship resistance and their verification by towing tests, compared on the example of a small urban ferry, are presented. The test results are made for both the bare hull and the hull with appendages (skeg, azimuthal propeller). Significant differences between results of the theoretical methods and experimental ones, especially in the case of the model with skegs and propulsion, are pointed out. The purposefulness of using several parametric methods and the use of average results at the preliminary design stage were also discussed.
Comparison of the exponential thermal transient parameterization methods with the SMTP method in the unipedicled DIEP flap computer modelling and simulation
- Mateusz Moderhak
2018 QIRT Journal
The aim of this paper is to compare the spatial contrast of the image descriptors obtained via three different thermal transient parameterization methods in Active Dynamic Thermography. The thermal constants and amplitude values of the one- and two- exponential parametrization are compared to the Simplified Magnitude-Temporal Parametrization method (SMTP). The comparison is performed using the data obtained by simulating the cold stress ADT exam of the partial computer model of the Deep Inferior Epigastric Perforators (DIEP) skin flap that is used e.g. in one of the breast reconstruction procedures. The results prove that all of the described methods are capable of detecting flap perforators. The SMTP method proved itself as a method with comparable spatial contrast to 1-exponential parametrization. Moreover it has some additional advantages like the excitation of non-uniformity insensitivity and far less computational complexity.
Comparison of Two Methods for the Determination of Selected Pesticides in Honey and Honeybee Samples
- Żaneta Bargańska
- Piotr Konieczka
- Jacek Namieśnik
2018 Pełny tekst MOLECULES
Developed and validated analytical methods for the determination of a wide spectrum of pesticide residues in honey and honeybee samples after the modification of QuEChERS extraction in combination with gas chromatography–tandem quadrupole mass spectrometry (GC-MS/MS) and liquid chromatography–tandem quadrupole mass spectrometry (LC-MS/MS) were discussed and compared. The developed methods were evaluated regarding the utilized equipment and reagents using Eco-Scale and compared in terms of extraction time, accuracy, precision, sensitivity and versatility, with similar procedures. The results proved that the QuEChERS protocol in combination with LC and GC techniques fulfills the requirements of green analytical chemistry, so it can be used as a tool in environmental monitoring. The recovery was 85–116% for honey and 85.5–103.5% for honeybee samples. The developed methods were successfully applied in monitoring real samples collected from three districts of Pomerania in Poland. Analysis of real samples revealed the presence of the following pesticides: bifenthrin, fenpyroximate, methidathione, spinosad, thiamethoxam, triazophos, metconazole and cypermethrin at levels higher than the MRLs established by the EU.
Complementary use of GCxGC–TOF–MS and statistics for differentiation of variety in biosolid samples
- Hubert Byliński
- Tomasz Dymerski
- Jacek Gębicki
- Jacek Namieśnik
2018 Pełny tekst MONATSHEFTE FUR CHEMIE
Formation of biosolid cakes, which are one of the main wastes generated in wastewater treatment plants, is connected with emission of many hazardous chemical compounds, including odoriferous ones. To optimize particular processes of biosolid cake processing, it is necessary to assess chemical composition of the gas mixtures containing the compounds released from the cakes. The paper proposes application of two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GCxGC–TOF–MS) to identification of the compounds released from four main types of biosolid cakes and to quantitative determination of the markers characteristic for particular types of cake. Based on the analysis of variance, the following compounds, which could be potential markers of the investigated biosolid cakes, were selected: 1-propanol, 2-hexanone, toluene, o-xylene, p-xylene, and organosulfur compounds (methanethiol, ethanethiol, dimethyl sulfide, dimethyl disulfide, and diethyl disulfide). Theoretical odour concentrations of four investigated types of biosolid cakes were determined, based on measured concentrations and olfactory thresholds of the aforementioned compounds. The highest concentration was revealed for a primary cake (634 ou/m3 ), whereas the lowest concentration was found for an excess cake (136 ou/m3 ) (ou/m3 —odour unit per m3 ; one odour unit is equivalent to collective odour threshold of odorants mixture present in 1 m3 ). The proposed methodology allows preliminary evaluation of the odour nuisance markers connected with formation of the biosolid cakes, without a need for quantitative analysis of all determined compounds.
Complementary Use of Multi-dimensional Gas Chromatography and Proton Transfer Reaction Mass Spectrometry for Identification of Rapeseed Oil Quality Indicators
- Tomasz Majchrzak
- Wojciech Wojnowski
- Tomasz Dymerski
- Jacek Gębicki
- Jacek Namieśnik
2018 Pełny tekst Food Analytical Methods
The change of concentration of various volatiles generated during frying may be an indicator of oil quality. Chemical compounds such as aldehydes, ketones, alcohols and carboxyl acids are the products of oxidation during thermal degradation of edible oils. Shown in this work is a complementary use of GC×GC-TOFMS and PTR-MS for the detection and determination of quality indicators of rapeseed oil. The former technique was used for the identification of potential markers and the latter for their quantitative determination. As a result of the GC×GC analysis, it was determined that 2-pentanone, heptane, octane, 1-heptanol and nonanal can be considered indicators of thermal degradation of rapeseed oil. Using PTR-MS, it was possible to monitor the concentration of these volatile indicators in real time. Based on the results of the analysis and of the reference method, it was concluded that 1-heptanol is best suited for the role of a quality indicator of thermal degradation of rapeseed oil.
Complex Corrosion Monitoring System for Crude Distillation Unit in Form of Neutral Network
- Agata Jażdżewska
- Kazimierz Darowicki
- Stefan Krakowiak
- Juliusz Orlikowski
2018 PROCEEDINGS OF THE IEEE
Complex and successful corrosion monitoring of refinery processes can significantly reduce material losses and failure risk. The developed corrosion monitoring system is based on online ultrasonic sensors, ER (electrical resistance) probes, gravimetric method and multipoint analytical analysis of chemical composition of the fluids. Additional online LPR (linear polarization resistance) sensors controlling corrosiveness of sour water are the part of monitoring system. LPR sensors on the sour water can be utilized for continuous control of chlorides content. The obtained data were used for selection of critical points in the atmospheric distillation unit and creating neutral network with defined factors which primarily influence the corrosion rate of each component. The database of standard and tolerable concentrations of main chemical species were defined as well as acceptable corrosion rates in each point. Main corrosion threats and proper technique of monitoring were discussed. The presented monitoring system can be utilized for proper blending of crude oils from different sources and diverse chemical composition. Such an approach can be useful for precise predicting safe service life of the component as well as the search for more corrosion resistive materials.
COMPOSITE MATERIAL SELECTION FOR A PATIENT TRANSFER ASSIST DEVICE
- Magda Dziaduszewska
- Martyna Zimna
2018 Pełny tekst Engineering of Biomaterials / Inżynieria Biomateriałów
Laminates - layered composites containing at least two elements (matrix and reinforcement) widely used in industry have also found their usage in medicine. Their main feature is the ability to modify the material in order to obtain the required properties. Depending on the needs, we can modify reinforcement, type of resin or the method of bonding substrates. Commonly used fibers are: carbon fiber, glass and aramid fibers; resins are epoxy, vinyl and polyester. The following commercial forms of fibers are distinguished: roving, mat and fabric (multidirectional and unidirectional - UDC) with several styles of bandwidth connections: differing in number of layers and the way they are combined (at various angles or in different ways of sewing/ plaiting) [1, 2].The main goal of this project is to select a proper composite material for a medical device – lightweight, durable and ergonomic patient lift which efficiently transfers patients between two plains. The material selection contains the choice of matrix, reinforcement, form of fibres, style of bandwidth, the thickness and the fibre mass for the individual layers of laminates, as well as the strength calculation.
Composite sandwich footbridge - measured dynamic response vs. FEA
- Łukasz Pyrzowski
- Bartosz Sobczyk
- Magdalena Rucka
- Mikołaj Miśkiewicz
- Jacek Chróścielewski
2018
The paper describes a process of in situ dynamic tests of a composite sandwich footbridge before its accepta-tion for exploitation in real traffic conditions. It is only a part of a big research task that includes design, manufacture and introduce practical application of the bridge. The in situ measured natural modes and fre-quencies are compared with numerically determined ones. Finite element analysis is established to estimate the behavior of the bridge. The obtained results present good correlation with the experimental values.
Composites in energy storing prosthetic feet
- Magda Dziaduszewska
- Marcin Wekwejt
2018 Pełny tekst European Journal of Medical Technologies
Composites reinforced with carbon and glass fibers have become the commonly used material in the production of energy storing prosthetic feet (ESPF/elastic feet prostheses). Their properties ensure a stable and light structure that allows for accumulation, storage and release of energy during walking, thus ensuring an increase in gait efficiency. Depending on the modification of the composite in terms of fiber selection, their form, type of combination and mass content, and the design of the prosthesis, the foot obtains different efficiency as the ratio of energy released to energy accumulated. The article characterizes ESPF’s in terms of mechanical and functional properties, compared properties of fibers and resins indicating the material that meets best the requirements towards elastic feet prostheses. Possible modifications of composite materials that influence the material properties and the work of the foot are also presented as well as an overview of selected ESPF prosthetic feet available on the market.
Composites of tin oxide and different carbonaceous materials as negative electrodes in lithium-ion batteries
- Andrzej Nowak
2018 Pełny tekst JOURNAL OF SOLID STATE ELECTROCHEMISTRY
Abstract Tin and tin oxide have been considered as suitable materials with high theoretical capacity for lithium ion batteries. Their low cost, high safety and other technical benefits placed them as promising replacements for graphite negative electrodes. The problem to overcome with tin oxide, as well as with other metallic materials, is high volume changes during alloying/dealloying, subsequent pulverization, delamination from current collectors following continuous degradation of the anode. To solve these issues different approaches have been applied. A number of various architectures from nanostructures to core-shell, porous, anchored and encapsulated have been studied to improve cycling performance. Much attention was paid to incorporate carbonaceous materials. Here, summarized results regarding utilization of tin oxide-carbonaceous negative electrode material are presented.
Comprehensive dimension scaling of multi-band antennas for operating frequencies and substrate parameters
- Sławomir Kozieł
- Adrian Bekasiewicz
2018 Pełny tekst
In this paper, low-cost and comprehensive redesign of multi-band antennas with respect to the operating frequencies and material parameters of the substrate is presented. Our approach exploits an inverse surrogate model identified based on a set of reference designs optimized at the level of coarse-discretization EM simulations of the antenna at hand. An iterative correction procedure is also implemented to account for the initial scaling errors (being a result of limited accuracy of the inverse model). The cost of the antenna re-design corresponds to a few high-fidelity EM simulations of the structure. Our considerations are illustrated using a dual-band patch antenna scaled w.r.t. both operating frequencies in the ranges of 1.5 GHz to 2.5 GHz and 5.0 GHz to 6.0 GHz, respectively, as well as the relative permittivity and thickness of the dielectric substrate (within the ranges of 0.7 mm to 1.5 mm, and 2.5 to 3.5, respectively). Several verification cases
Comprehensive stabilization of all streams of solid residues formed during sewage sludge thermal treatment – Case study
- Bartłomiej Cieślik
- Marek Zając
- Agnieszka Gałuszka
- Piotr Konieczka
2018 Pełny tekst JOURNAL OF CLEANER PRODUCTION
Modern wastewater treatment plants are currently struggling with the problem of processing and ecological management of sewage sludge. Thermal utilization is a frequently used practice of excess sludge utilization especially in large wastewater treatment plants, which seems to be a quite promising concept. However, during thermal treatment, fractions of ashes and dusts are generated. Such wastes, especially the dust fraction, can be potentially harmful to the environment. Therefore, the mentioned wastes should be stabilized. In this paper, a comprehensive method of stabilization is presented. Ash fraction, produced during sewage sludge thermal treatment, is used for dust fraction stabilization, hence no other solid medias, except cheap, commercially available cement, have to be used for stabilization. Laboratory and industrial scale trials were performed. Based on the results of the conducted research it can be stated that dust and ash fractions obtained from one facility can be stabilized together and the final product is safe for the environment since no potentially toxic elements are leached from the materials. There is a potential for improving the proposed method of stabilization to create fully environmentally safe construction materials.