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Publications Repository
Gdańsk University of Technology

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Publications from the year 2015

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  • Impact of enhanced pretreatment on biological nutrient removal in municipal wastewater treatment plants
    • Krzysztof Czerwionka
    • Magdalena Szyszko
    • Agnieszka Tuszyńska
    • Jacek Mąkinia
    2015

    The aim of this study was to determine the effect of enhanced primary treatment on: increasing primary sludge production for increased biogas production; reducing the organic load on downstream biological treatment processes and thereby reducing energy consumption for aeration; denitrification and enhanced biological phosphorus removal (EBPR) rates in the activated sludge system. For this purpose, three commercial organic polymers (termed flocculent 1, 2 and 3) and ZnSO4 were selected for batch experiments, including two-phase tests (anaerobic P release (PRR) followed by anoxic P uptake (PUR) and anoxic N uptake (NUR)). The samples of raw wastewater and activated sludge were collected from three municipal wastewater treatment plants in Gdansk, Gdynia and Slupsk located in northern Poland. The experiments were carried out with the raw wastewater after two-hours sedimentation and raw wastewater after sedimentation with dosing the above mentioned reagents. The obtained results showed that the maximum removal of COD was in the case of flocculent no. 3 (61.63±7.96% with respect to raw wastewater and 37.47±11.68% with respect to wastewater after two-hours sedimentation). The experimental tests revealed that the addition of flocculent no. 3 could provide a reduction of nitrogen (N) and phosphorus (P) above 15.52±8.35% and 29.25±6.53%, respectively. It was found, that there were no substantial discrepancies on biological nutrient removal (BNR) processes in the two-phase experiments without and with addition of the organic polymers. In experiments without addition of organic polymers, the NUR, PRR and PUR were 1.31±0.49 gN.gVSS-1.h-1, 7.28±2.59 gP.gVSS -1.h-1 and 1.19±0.97 gP.gVSS -1.h-1, respectively. For comparison, in experiments with flocculants, the NUR, PRR and PUR were 1.63±0.65 gN.gVSS -1.h-1, 7.29±3.65 gP.gVSS -1.h-1 and 1.46±0.79 gP.gVSS -1.h-1, respectively. The experimental results confirmed that CEPT can be used as an alternative for the treatment of wastewater to traditional biological processes.

  • Impact of influent wastewater quality on nitrogen removal rates in multistage treatment wetlands
    • Magdalena Gajewska
    • K. Jóźwiakowski
    • A. Ghrabi
    • F. Masi
    2015 Full text ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH

    Nitrogen removal in treatment wetlands is influenced by many factors, and the presence of electron donors (biodegradable organic matter) and electron acceptors (nitrate ions) is the main limiting one; for obtaining these conditions, multistage treatment wetlands (MTWs) are required, where an extensive nitrification can be obtained in the first stages under aerobic conditions leaving then to the following anoxic/anaerobic stages the duty of the denitrification. Most of the biodegradable organic matter is however oxidised in the first stages, and therefore, the inlet to the denitrification beds is usually poor of easily degradable carbon sources. This study is comparing the long-term performances obtained at several MTWs operating in Europe (North and South) and North Africa in order to understand if there is a significant avail in making use of the influent chemical oxygen demand (COD)/N ratio during the design phase for ensuring proper performances in terms of N overall removal. The statistic analysis performed in this study have shown that MTWs are capable to ensure sufficient removal of both organic and nutrients even in unfavourable proportions of macronutrients (C and N). The usual assumptions for conventional biological treatment systems concerning adequate C/N ratios seem to be dubious in case of wastewater treatment in MTWs.

  • Impact of Initial Population on Evolutionary Path Planning Algorithm
    • Łukasz Kuczkowski
    • Roman Śmierzchalski
    2015

    In this paper an impact of initial population on evolutionary path planning algorithm is presented. Tested algorithm is used to determine close to optimal shippaths in collision avoidance situation. For this purpose a path planning problem is defined. A specific structure of the individual path and fitness function is presented. For the simulation purposes a close to real tested environment is created. Four tests are performed. For each test 50 initial population is used. The results are compared in terms of repeatability of the obtained solution. Undertaken research allow to conclude whether presented algorithm is resistant to random initial population or require a preselected initialization.

  • Impact of Microphytobenthos Photosynthesis on the Characteristics of the Echo Signal from Baltic Sandy Sediments
    • Natalia Gorska
    • Ewa Kowalska-Duda
    • Jacek Marszal
    • Jan Schmidt
    • Zygmunt Klusek
    2015 Full text Archives of Acoustics

    The understanding the influence of biological processes on the characteristics of the signals backscattered by the sea floor is crucial in the development of the hydroacoustical benthic habitat classification techniques. The impact of the microphytobenthos photosynthesis on the acoustical backscattering properties of the Atlantic sandy sediments was previously demonstrated by Holliday et al. (2004) and Wildman and Huettel (2012). To account for the sensitivity of the hydroacoustical classification techniques to the backscattering properties of local marine sediments, it is important to understand the microphytobenthos photosynthesis impact for the Baltic Sea where the techniques are being actively developed now. This is the main motivation of the paper. In the paper the influence of the microphytobenthos photosynthesis on the characteristics of the echo signals reflected by sandy sediments in the typical Baltic temperature and the salinity conditions is discussed. The interdisciplinary multiday laboratory experiment was conducted to study the impact of benthic microalgal photosynthesis on the characteristics of the echo signal reflected by sandy sediments. Hydroacoustical data were collected under controlled constant light, temperature and salinity conditions. The oxygen content at different levels of the water column was simultaneously monitored.

  • Impact of radio wave polarisation on off-body communications in indoor environments
    • Sławomir Ambroziak
    • Luis M. Correia
    • Ryszard Katulski
    • Michał Maćkowiak
    2015

    This paper describes the measurements and the analysis of the impact of radio wave polarisation on off-body communications in Body Area Networks in indoor environments. Measurements on polarisation impact are briefly described. Five investigated scenarios with different body postures and different antenna placements are characterised. The difference between the vertical and horizontal components of the received radio signal are analysed. The best results have been obtained for scenarios with a vertical polarised transmitting antenna, especially for the case when the maximum gain of the transmitting antenna is directed towards the receiving one.

  • Impacts on human health in the Arctic owing to climate-induced changes in contaminant cycling – The EU ArcRisk project policy outcome
    • Józef Pacyna
    • Ian Cousins
    • Crispin Halsall
    • Arja Rautio
    • Janet Pawlak
    • Elisabeth G. Pacyna
    • Kyrre Sundseth
    • Simon J. Wilson
    • John Munthe
    2015 ENVIRONMENTAL SCIENCE & POLICY

    Results of the EU ArcRisk project on human health impacts in the Arctic owing to climate-induced changes in contaminant cycling are summarized in the context of their policy application. The question on how will climate change affect the transport of selected persistent organic pollutants (POPs) and mercury, both to and within the Arctic has been addressed, as well as the issue of human health impacts of these pollutants in the Arctic in relation to exposed local populations. It was concluded that better characterization of primary and secondary sources of POPs and more accurate quantification of current and future releases of POPs from these sources are needed for better prediction of environmental exposure to these contaminants and interpretation of monitoring data. Further improvement of fate and transport modeling in the physical environment is necessary in order to consider in the models not only the relatively well studied direct effects of climate change (e.g., changes in temperature, ice and snow cover, precipitation, wind speed and ocean currents) on contaminants fate and behavior but also indirect effects, e.g., alterations in carbon cycling, catchment hydrology, land use, vegetation cover, etc. Long-term environmental monitoring of POPs (at multiple sampling stations within and outside the Arctic and at regular sampling intervals facilitates temporal trend analysis) and measurements of concentrations in human milk and blood plasma are needed. Finally, more information should be gathered on the human health effects of newly identified POPs, such as perfluorooctanesulfonic acid (PFOS), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), and other substances with POP-like characteristics, particularly the effects on very young (including fetus) and elderly subgroups of the human population. The ArcRisk developed methodologies and tools that can be used in further studies to resolve various uncertainties already defined in the analysis of climate change impacts on POPs and mercury behavior and effects in the Arctic. The ArcRisk project has also developed very valuable databases that can be regarded as a starting point in further studies.

  • IMPACT-TOUGHNESS INVESTIGATIONS OF DUPLEX STAINLESS STEELS
    • Santina Topolska
    • Jerzy Łabanowski
    2015 Materiali in Tehnologije

    Duplex stainless steels are very attractive constructional materials for use in aggressive environments because of their several advantages over austenitic stainless steels. Duplex steels have excellent pitting and crevice corrosion resistance, are highly resistant to chloride stress-corrosion cracking and are about twice as strong as common austenitic steels. Better properties are associated with their microstructures consisting of ferrite and austenite grains. However, with certain thermal treatments, these excellent properties may be reduced due to undesired changes in the steel microstructure, related mainly to different solid-state-precipitation processes. The impact toughness of the commercial 2205 duplex stainless steel and the higher-alloy super-duplex 2507 steel was investigated. Both steels were submitted to the ageing treatment in a temperature range between 500 °C and 900 °C with the exposure times of 6 min , 1 h and 10 h; in addition, light microscope examinations, hardness measurements and impact-toughness tests were performed. The main objective of the investigations was to determine the effect of the change in the microstructure on the mechanical properties of the steel.

  • IMPEDANCE MEASUREMENT MODULE FOR GAS SENSORS WITH TEMPERATURE CONDITIONING FEATURE
    • Grzegorz Lentka
    • Jakub Mróz
    2015

    The paper presents an impedance measurement module which is aimed for gas sensor. Sensor’s heater temperature conditioning and modulation feature is available in order to allow implementation of different techniques improving selectivity and sensitivity of gas sensors. The measurement module uses three-parameter sine-fitting technique for impedance measurement. To monitor sensor temperature, the resistance of the sensor’s heater is measured while continuously maintaining temperature control with the aid of PID regulator.

  • Impedance monitoring of fuel cell stacks
    • Paweł Ślepski
    • Ewa Janicka
    • Kazimierz Darowicki
    • Bogusław Pierożyński
    2015 Full text JOURNAL OF SOLID STATE ELECTROCHEMISTRY

    This paper presents an innovative, electrochemical impedance method for monitoring of electrochemical behaviour of a multi-cell, direct methanol fuel cell (DMFC) device. This method not only provides classical voltage changes at successive cells but also allows their detailed impedance behaviour to be presented. Impedance characteristics of individual cells within a fuel cell stack (depending on actual operating conditions) are obtained via numerous electrochemical tasks, including simultaneous determination of each cell’s impedances, performance optimization of the fuel cell stack and effective detection of faulty cells within the stack. The above concerns in situ conditions. The effectiveness of the present method was studied here on a seven-cell, commercially made DMFC stack. In order to effectively detect faulty cells, selected experiments were carried out with insufficient amount of oxygen supplied to a cathode input (ca. 25 % of optimal oxidant dose was used).

  • Implementacja automatycznych metod strojenia nastaw regulatora PID w sterowniku programowalnym
    • Marek Adamkiewicz
    • Paweł Damps
    • Karol Gryń
    • Robert Piotrowski
    2015 Full text Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

    Zainteresowanie środowiska przemysłowego klasycznymi algorytmami regulacji, dającymi akceptowalne wyniki pracy i stabilność w odniesieniu do zmiennych warunków otoczenia, wciąż jest bardzo duże. W artykule opisano wybrane inżynierskie metody doboru nastaw regulatora PID. Przedstawiono implementację sprzętową jednej z nich (metoda Åströma-Hägglunda) w sterowniku programowalnym PLC, umożliwiającą automatyczny dobór nastaw regulatora. Na podstawie symulacji w pętli sprzętowej liniowego układu regulacji PID dokonano analizy porównawczej pracy tego układu dla nastaw regulatora obliczonych trzema metodami inżynierskimi.

  • Implementacja procesów biznesowych w technologiach Smart Cities
    • Aleksander Orłowski
    • Cezary Orłowski
    • Tomasz Sitek
    • Artur Ziółkowski
    • Paweł Kapłański
    • Witold Pokrzywnicki
    2015 Full text Przedsiębiorstwo we współczesnej gospodarce - teoria i praktyka

    Celem artykułu jest prezentacja wyników badań nad opracowaniem metody implementowania procesów biznesowych w systemach Smart Cities. Metoda została opracowana w trakcie badań prowadzonych w ramach budowy systemu Smart Cities dla Gdańska bazuje na podstawowych mechanizmach zarządzania projektami wytwórczymi (czerpiąc z dobrych praktyk m.in. metodyki RUP) oraz zasadach biznesowo zorientowanego wytwarzania, gdzie rola modelowania procesów biznesowych jest kluczowa dla implementacji funkcjonalności systemów informatycznych.

  • Implementation of daylight design strategies in urban planning - barriers to application in Poland
    • Natalia Sokół
    2015

    This paper reflects on studies done in the area of daylight design methods with regard to principles that can be applied in architecture and urban planning strategies. The paper addresses barriers to the application of new daylight design methods in urban planning, and in particular discusses current Polish building regulations in the context of daylight design. The results of the pilot study carried out among 82 participants show a growing demand for better daylight education and an urgent need for revision of the existing outdated lighting recommendations in Poland. In conclusion, the pilot study illustrates the importance of daylight as a natural resource considered essential in sustainable approaches to urban planning, and highlights the belief that daylight and electric light projects should be holistically integrated in the implementation of the town lighting plan.

  • Implementation of TVDI calculation for coastal zone
    • Tomasz Bieliński
    2015

    Paper will show an implementation of TVDI (Temperature-Vegetation-Dryness Index) algorithm on GPU (Graphics Processing Unit). Calculation of this index is based on LST (Land Surface Temperature) and NDVI (Normalized Difference Vegetation Index). Discussed results are based on multi-spectral imagery retrieved from AVHRR3 sensors for area of Poland, especially from region of Gdańsk coastal zone. All phases of TVDI implementation are modified in respect to GPU platform. Specific aspects of on GPU implementation will be compared with CPU implementation. At the end, time measurements of images processing will be shown and analysed. Also all technical means used to achieve mentioned result will be briefly presented.

  • Implementing the consumer-based brand equity scale for beer brands – a Tyskie and Żywiec case study
    • Bruno Schivinski
    • Przemysław Łukasik
    2015 Full text Marketing i Zarządzanie

    The concept and management of brand equity is of great importance to scholars and managers. In this article, brand equity is approached from the consumers’ point of view i.e., consumer-based brand equity (CBBE) in the context of two beer brands offered in Poland – Tyskie and Żywiec. The objective of this article is to demonstrate how managers can implement the CBBE scale as an audit and monitoring instrument to their brands. A sample of 311 respondents was analyzed to generate scores for brand awareness, brand associations, perceived quality, and brand loyalty. Additionally, scores for overall brand equity were also generate. The results demonstrated that the scores of brand awareness for Żywiec was higher than Tyskie, however, Tyskie scored higher for brand associations, perceived quality, and brand loyalty. The brand Tyskie also achieved better overall brand equity scores than Żywiec.

  • Improved surface coverage of an optical fibre with nanocrystalline diamond by the application of dip-coating seeding
    • Robert Bogdanowicz
    • Michał Sobaszek
    • Jacek Ryl
    • Marcin Gnyba
    • Mateusz Ficek
    • Łukasz Gołuński
    • Wojtek J. Bock
    • Mateusz Śmietana
    • Kazimierz Darowicki
    2015 DIAMOND AND RELATED MATERIALS

    Growth processes of diamond thin films on the fused silica optical fibres (10 cm in length) were investigated at various temperatures. Fused silica pre-treatment by dip-coating in a dispersion consisting of detonation nanodiamond (DND) in dimethyl sulfoxide (DMSO) with polyvinyl alcohol (PVA) was applied. Nanocrystalline diamond (NCD) films were deposited on the fibres using the microwave plasma assisted chemical vapour deposition (MW PA CVD) method. The longitudinal variation of NCD morphology, structure and optical parameters were specifically investigated. The evolution of the film morphology and film thickness along the fibre length was studied using scanning electron microscopy (SEM). The chemical composition of the NCD film was examined with micro-Raman Spectroscopy. The sp3/sp2 band ratio was calculated using the Raman spectra deconvolution method. An approximately 5 cm-long homogeneous diamond film has been obtained on the surface of the fibre sample. Thickness, roughness and optical properties of NCD films in the VIS–NIR range were investigated on the reference quartz slides using spectroscopic ellipsometry. The samples exhibited relatively low deviations of refractive index (2.3 ± 0.25) and extinction coefficient (0.05 ± 0.02) along the length of 5 cm, as estimated at a wavelength of 550 nm. In order to show the effectiveness of deposition process on optical fibres, diamond films were also grown on the fibre with induced long-period grating (LPG). The results of transmission measurements demonstrated that an LPG with diamond overlay exhibits the appropriate dependency on the optical properties of external medium. Thus, the deposition process has a negligible effect on the fibre transmission properties.

  • Improvement of time difference of arrival measurements resolution by using fractional delay filters in a direct sequence-code division multiple access radionavigation system
    • Jarosław Sadowski
    2015 Full text IET Radar Sonar and Navigation

    This study presents a method of improving time measurements resolution in a direct sequence-code division multiple access receiver by using a fine code tracking loop based on fractional delay filtering of a despreading sequence. It briefly describes the structure of a generic digital code tracking loop and the proposed modification which allows to measure time difference of arrival values with the subsample resolution, together with suggestions to reduce computational complexity by storing the set of samples of fractionally-delayed signals in memory. The proposed solution was tested in a laboratory and in real environment in a radionavigation system built in Gdansk University of Technology.

  • Improving Control Dynamics of PMSM Drive by Estimating Zero-Delay Current Value
    • Leszek Jarzębowicz
    • Artur Opaliński
    • Maciej Cisek
    2015 Full text Elektronika Ir Elektrotechnika

    Dynamic performance of current control loop still remains crucial for position-, speed-, and torque-controlled drives. In the study, a current loop solution has been designed for field oriented control of permanent magnet synchronous motors (PMSM). It enhances typical PI controller with an estimator of zero-delay current (ZDC) value. The ZDC estimation allows for selecting substantially higher controller gain. It reduces control loop step response rise time to a single control cycle, which is the shortest technically possible value, while avoiding overshoot. The method does not require any hardware changes and it needs only negligible processing overhead. Both simulations made and experimental results obtained in the study have proved the effectiveness of the proposed solution.

  • Improving css-KNN Classification Performance by Shifts in Training Data
    • Karol Draszawka
    • Julian Szymański
    • Francesco Guerra
    2015

    This paper presents a new approach to improve the performance of a css-k-NN classifier for categorization of text documents. The css-k-NN classifier (i.e., a threshold-based variation of a standard k-NN classifier we proposed in [1]) is a lazy-learning instance-based classifier. It does not have parameters associated with features and/or classes of objects, that would be optimized during off-line learning. In this paper we propose a training data preprocessing phase that tries to alleviate the lack of learning. The idea is to compute training data modifications, such that class representative instances are optimized before the actual k-NN algorithm is employed. The empirical text classification experiments using mid-size Wikipedia data sets show that carefully cross-validated settings of such preprocessing yields significant improvements in k-NN performance compared to classification without this step. The proposed approach can be useful for improving the effectivenes of other classifiers as well as it can find applications in domain of recommendation systems and keyword-based search.

  • Improving depth maps of plants by using a set of five cameras
    • Adam Kaczmarek
    2015 Full text JOURNAL OF ELECTRONIC IMAGING

    Obtaining high-quality depth maps and disparity maps with the use of a stereo camera is a challenging task for some kinds of objects. The quality of these maps can be improved by taking advantage of a larger number of cameras. The research on the usage of a set of five cameras to obtain disparity maps is presented. The set consists of a central camera and four side cameras. An algorithm for making disparity maps called multiple similar areas (MSA) is introduced. The algorithm was specially designed for the set of five cameras. Experiments were performed with the MSA algorithm and the stereo matching algorithm based on the sum of sum of squared differences (sum of SSD, SSSD) measure. Moreover, the following measures were included in the experiments: sum of absolute differences (SAD), zero-mean SAD (ZSAD), zero-mean SSD (ZSSD), locally scaled SAD (LSAD), locally scaled SSD (LSSD), normalized cross correlation (NCC), and zero-mean NCC (ZNCC). Algorithms presented were applied to images of plants. Making depth maps of plants is difficult because parts of leaves are similar to each other. The potential usability of the described algorithms is especially high in agricultural applications such as robotic fruit harvesting.

  • Improving Effectiveness of SVM Classifier for Large Scale Data
    • Jerzy Balicki
    • Julian Szymański
    • Marcin Kępa
    • Karol Draszawka
    • Waldemar Korłub
    2015

    The paper presents our approach to SVM implementation in parallel environment. We describe how classification learning and prediction phases were pararellised. We also propose a method for limiting the number of necessary computations during classifier construction. Our method, named one-vs-near, is an extension of typical one-vs-all approach that is used for binary classifiers to work with multiclass problems. We perform experiments of scalability and quality of the implementation. The results show that the proposed solution allows to scale up SVM that gives reasonable quality results. The proposed one-vs-near method significantly improves effectiveness of the classifier construction.