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Repozytorium publikacji
Politechniki Gdańskiej

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  • New transition curve adapted to railway operational requirements
    • Władysław Koc
    2019 JOURNAL OF SURVEYING ENGINEERING-ASCE

    The paper points to the limited possibilities of improving the existing situation in the area of transition curves used in geometrical layouts of the railway track. Difficulties in the practical implementation and maintenance of very small horizontal ordinates of the transition curve and the ordinates of the gradient due to cant in the initial section, appearing on smooth transition curves, were indicated. The main reason for this situation was the excessive smoothing of the curvature in their initial section. Employing the method of curvature identification by differential equations, a new form of the curve was obtained, which was referred to as the "smoothed transition curve". A definite advantage of this curve was shown, from the implementation point of view, over representing the smooth transition curves of the Bloss curve and the parametric curve. It seems that it could successfully compete with the commonly used clothoid, to which it is similar in the initial section, while it differs significantly along its further length, especially in the final section, where it provides a gentle entry from the transition curve into a circular arc.

  • New-fangled sources of cellulose extraction: comparative study of the effectiveness of Cissus latifolia and Ficus benghalensis cellulose as a filler
    • Arunima Reghunadhan
    • Nayana G. Sivan
    • Shibina S. K.
    • Siji K. Mary
    • Rekha Rose Koshy
    • Janusz Datta
    • Sabu Thomas
    2019 Materials Chemistry Frontiers

    Recycled polymers and biopolymers are receiving a great deal of attention these days. If these two can be combined, it will lead to an environment-friendly green material with a great deal of applications. Here the present work is about incorporating bio-based fillers in a recycled polyurethane matrix. Two unusual and extremely novel sources of cellulose have been proposed. The celluloses obtained from Cissus latifolia and Ficus benghalensis were selected as sources. These sources have not been utilized and reported elsewhere to date. The cellulose modified samples of recycled polyurethane were analyzed using FTIR, scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) to have a preliminary idea about the combination. We found that these were successful as fillers in the matrix. The percentage of crystallinity was decreased in both the composites, which indicates the miscibility. Comparing the two sources, Cissus latifolia based cellulose was more effective in producing interesting morphologies and they had a percentage crystallinity of 75%, which was very high compared to all the reported works.

  • Nickel-nanodiamond coatings electrodeposited from tartrate electrolyte at ambient temperature
    • Irina Makarova
    • Illia Dobryden
    • Dmitry Kharitonov
    • Aliaksandr Kasach
    • Jacek Ryl
    • Eveliia Repo
    • Esa Vuorinen
    2019 Pełny tekst SURFACE & COATINGS TECHNOLOGY

    In this study, nanocrystalline Ni and Ni-diamond coatings were obtained by electrodeposition from tartrate electrolyte at ambient temperature aiming at improving corrosion and wear properties of the material. The created surfaces were investigated with regard to microhardness, adhesion, wear- and corrosion-resistance. The various methods such as atomic force microscopy, scanning electron microscopy, electrochemical impedance spectroscopy and linear polarization technique were applied to study the coating surface properties. The introduction of nanodiamond particles into the coating led to a rougher surface structure and a bigger grain size in comparison to bare nickel coating. Our study shows that the addition of 5·10−2 (g dm−3) of nanodiamonds to the plating bath is enough to obtain composite coatings with a clear increase in microhardness and wear resistance. The slightly improved corrosion resistance of the coating, decrease in corrosion current density from 0.41 to 0.14 μA cm−2 in neutral chloride-containing medium, and nobler values of the corrosion potential were also observed.

  • Niekonwencjonalne metody odzysku ciepła odpadowego na statkach
    • Roman Liberacki
    2019 Pełny tekst Journal of Polish CIMEEAC

    W artykule opisano kilka metod odzysku ciepła odpadowego, które nie znalazły jeszcze szerokiego zastosowania na statkach. Obecnie, powszechnie wykorzystuje się ciepło spalin do wytwarzania pary wodnej grzewczej, a ciepło wody chłodzącej cylindry silników głównych - do wytwarzania wody słodkiej w wyparownikach podciśnieniowych. Znacznie rzadziej, para wodna lub spaliny służą do napędu turbogeneratorów. Metody te są jednak wykorzystywane od wielu lat i mogą być uznane za konwencjonalne. Proponowane na forum międzynarodowym dalsze ograniczenia emisji dwutlenku węgla, skłaniają do poszukiwania rozwiązań pozwalających na jeszcze szersze, niż dotychczas, odzyskiwanie traconej energii. Można to czynić zastępując obiegi parowe wodne obiegami organicznymi Rankina, które wykorzystują czynniki robocze wrzące w niskich temperaturach. Zalicza się tu różnego rodzaju węglowodory i inne czynniki robocze stosowane w chłodnictwie. Pozwala to na lepsze wykorzystanie ciepła spalin. Umożliwia też sięgnięcie po ciepło tracone w powietrzu doładowującym, wodzie chłodzącej cylindry, oleju smarowym - zarówno silników głównych jak i silników pomocniczych. Oprócz organicznych obiegów Rankina, zastosować można także obieg Kaliny, wykorzystujący mieszaninę wody i amoniaku, czy obieg trilateralny, gdzie ekspansja czynnika roboczego w maszynie cieplnej, odbywa się tuż po osiągnięciu przez niego stanu wrzenia. Rozważa się też rozwiązania wzorowane na silniku Stilla, czy silnikach sześciosuwowych. Można także budować układy, gdzie odzyskiwane ciepło jest bezpośrednio konwertowane na energię elektryczną w generatorach termoelektrycznych albo na energię mechaniczną w silnikach wykorzystujących nitinol, czyli stop niklu i tytanu. Wszystkie te niekonwencjonalne rozwiązania pozwalają na oszczędność paliwa od kilku do około dziesięciu procent, w odniesieniu do ilości paliwa zużywanego przez silniki główne.

  • Nikola Tesla i jego niezwykłe osiągnięcia
    • Dariusz Świsulski
    2019 Śląskie Wiadomości Elektryczne

    W artykule przybliżono sylwetkę amerykańskiego wynalazcy serbskiego pochodzenia Nikoli Tesli. Omówiono jego studia i pracę, współpracę i konflikt z Edisonem oraz pierwsze patenty. Przedstawiono wybrane wynalazki i osiągnięcia tego niezwykłego inżyniera i wizjonera, którego celem było wykorzystanie wynalazków do poprawy ludzkiego życia. Jednym z największych osiągnięć Tesli było znalezienie praktycznego zastosowania dla prądu przemiennego.

  • Niskokosztowe mierniki pyłu PM10
    • Bartosz Szulczyński
    • Jacek Gębicki
    2019

    Ochrona środowiska to jedna z dziedzin, w których ocena jakości powietrza atmosferycznego ma istotne znaczenie. Jakość powietrza zarówno wewnętrznego, jak i zewnętrznego jest jednym z kluczowych czynników wpływających na zdrowie człowieka. Ocena jakości powietrza nie jest jednak zadaniem łatwym. Powietrze jest bowiem złożonym układem, podlegającym zmianom nawet w krótkim czasie Jedną z głównych przyczyn występowania przekroczeń dopuszczalnych poziomów stężeń i dopuszczalnych poziomów stężeń docelowych (PM10, ozon i benzo(a)piren) w aglomeracji trójmiejskiej jest występowanie niskiej emisji z indywidualnych systemów grzewczych oraz emisji liniowej z ciągów komunikacyjnych. Prowadzenie monitoringu jakości powietrza w ramach Państwowego Monitoringu Środowiska wymaga użycia odpowiedniej ilości urządzeń pomiarowych spełniających wymagania stawiane metodom odniesienia. Taka sytuacja wiąże się z ponoszonymi wysokimi nakładami finansowymi. Zastosowanie w prowadzeniu monitoringu jakości powietrza mierników opartych na niskokosztowych czujnikach optycznych wydaje się słuszną i obiecującą drogą. Wdrożenie tych urządzeń nie tylko spowoduje obniżenie kosztów prowadzenia monitoringu, ale również może zwiększyć gęstość punktów pomiarowych, co w konsekwencji zapewni uzyskanie bardziej miarodajnej informacji o jakości powietrza na danym terenie. W pracy przedstawiono wyniki badań terenowych przeprowadzonych na terenie Aglomeracji Trójmiejskiej w celu oceny przydatności niskokosztowych czujników PM10 w monitorowaniu jakości powietrza atmosferycznego. Wyniki zestawiono z wynikami uzyskanymi za pomocą metod referencyjnych. Ponadto oceniono wpływ czynników zewnętrznych (wilgotność, ciśnienie, temperatura) na uzyskane wyniki.

  • Nitrogen and phosphorus compounds in coastal aquifers in Puck municipality area (northern Poland)
    • Dawid Potrykus
    • Małgorzata Pruszkowska-Caceres
    • Beata Jaworska-Szulc
    • Wioletta Gorczewska-Langner
    • Anna Gumuła-Kawęcka
    • Adam Szymkiewicz
    • Lidia Dzierzbicka-Głowacka
    2019

    1. Groundwater study shows local variations in chemical composition of selected aquifers caused by human impact The diversity is mainly manifested in • time variation of groundwater chemical composition of all analyzed parameters especially in shallow aquifers (Q1) • relationship between t he ground water chemical composition and depth of the aquifer where an inverse concentration distribution occurs higher concentrations are observed in shallow aquifers (Pa and Q1) • mosaic spatial distribution of the pollution indicators which means pollution has a local character caused by anthropogenic activity 2. Composition of the basic pollution indicators in groundwater shows local impact of agriculture as well as contamination from households and farms which can potentially influence the quality of water in Puck Bay via SGD This is a subject of ongoing research

  • Nitrogen dioxide gas-sensing detection with GO modified CuO thin films
    • Aleksandra Szkudlarek
    • Michał Kawa
    • Grzegorz Jasiński
    • Piotr Jasiński
    • Artur Rydosz
    2019

    Gas sensors have been continuously developed over the last few decades for several applications including air quality monitoring, automotive industry and recently for medical use. Gas sensors are usually based on metal oxides (MOXs), such as SnO2, TiO2, ZnO, WO3, CuO. Recently, new materials such as graphene oxide and heterostructures of graphene oxide and metal oxides are utilized for gassensing applications.

  • Noise in electrical double-layer capacitors (EDLCs)
    • Janusz Smulko
    • Arkadiusz Szewczyk
    • Łukasz Lentka
    2019 Pełny tekst

    We present methods and problems of noise measurements in electrical double-layer capacitors (EDLC). Detailed noise equivalent electronic circuit is considered, and two possible ways of observations of random processes generated in the EDLCs structures are studied. We conclude that noise is a useful tool for characterization of the EDLC structures and their state-of-health, as in other materials and electronic devices. Eventual, practical applications of noise measurements are proposed to determine the state-of-health of the EDLCs.

  • Non-conventional approach in single-sided lapping process: kinematic analysis and parameters optimization
    • Adam Barylski
    • Norbert Piotrowski
    2019 Pełny tekst INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY

    The lapping process is strongly affected by a number of input parameters. One of the fundamental mechanical processes in lapping is the abrasive effect of particles. In order to examine the influence of the kinematic parameters on the lapping uniformity of unconventional single-sided machine, numerical simulations of particles sliding trajectories are performed. Changing the kinematic parameters, e.g., rotational velocities or position of the conditioning rings together with the workpieces can be used for correcting the profile of an active surface of the lap. This paper provides a basic guide to the kinematic parameter settings of single-sided lapping process. Furthermore, an unconventional single-sided lapping system, where a conditioning ring performs additional motion during the machining, is described. Simulation results show that the rotational speed ratio of the conditioning ring to the lapping plate k1 and the period ratio of the reciprocating motion to the lapping plate rotary motion k2 represent the relationships among the three basic motions of unconventional lapping systems and are major factors affecting trajectory distribution. Material removal rate and trajectory density parameter are proposed to optimize the kinematic parameters for better uniformity of lapping plate wear. The preferred kinematic parameter values for single-sided lapping system with reciprocating motions and the assumed size of the machine are k1=0,78 and k2=2. The general results were validated on a specially designed test stand.

  • Non-Destructive Testing of a Sport Tribune under Synchronized Crowd-Induced Excitation Using Vibration Analysis
    • Karol Grębowski
    • Magdalena Rucka
    • Krzysztof Wilde
    2019 Pełny tekst Materials

    This paper presents the concept of repairing the stand of a motorbike speedway stadium. The synchronized dancing of fans cheering during a meeting brought the stand into excessive resonance. The main goal of this research was to propose a method for the structural tuning of stadium stands. Non-destructive testing by vibration methods was conducted on a selected stand segment, the structure of which recurred on the remaining stadium segments. Through experiments, we determined the vibration forms throughout the stand, taking into account the dynamic impact of fans. Numerical analyses were performed on the 3-D finite element method (FEM) stadium model to identify the dynamic jump load function. The results obtained on the basis of sensitivity tests using the finite element method allowed the tuning of the stadium structure to successfully meet the requirements of the serviceability limit state.

  • Non-enzymatic flexible glucose sensing platform based on nanostructured TiO2–Au composite
    • Katarzyna Grochowska
    • Jacek Ryl
    • Jakub Karczewski
    • Gerard Śliwiński
    • Adam Cenian
    • Katarzyna Siuzdak
    2019 Pełny tekst JOURNAL OF ELECTROANALYTICAL CHEMISTRY

    All over the world the number of people suffering from diabetes and related complications is drastically growing. Therefore, the need for accurate, reliable and stable sensor for monitoring of glucose in human body fluids is becoming highly desirable. In this work we show that material composed of gold layers deposited onto TiO2 nanotubes (NTs) formed onto the flexible Ti foil exhibits great response toward glucose oxidation and can be successfully used as electrodes in non-enzymatic and non-invasive electrochemical sensors. TiO2NTs have been prepared via anodization process followed by calcination at 450 °C in order to ensure formation of anatase crystalline phase. Next, gold layers (up to 100 nm) have been deposited on the NTs by means of the magnetron sputtering. The SEM imaging confirmed presence of the well-aligned nanotubes and preservation of their initial architecture after metal deposition for Au thicknesses up to 50 nm. Basing on electrochemical results in the presence of glucose in neutral and alkaline solutions, the optimal Au thickness was found to ensure both the best response and cost-effectiveness. The detection limit of 50 μM and sensitivity of 45 μA/cm2mM obtained under neutral conditions confirm that prepared material can be used for glucose detection at levels typical for blood, urine or saliva. Moreover, the proposed electrodes exhibit great tolerance to extensive exploitation and multiple bending.

  • Non-isolated resonant quasi-Z-source network DC–DC converter
    • Marek Adamowicz
    2019 Pełny tekst ELECTRONICS LETTERS

    A novel non-isolated resonant quasi-impedance (quasi-Z)-source network DC–DC converter is proposed. The resonant impedance source network is derived from the quasi-Z-source network by including the autotransformer-based resonant cell instead of the second inductor of the quasi-Z-network. The leakage inductance of the autotransformer and two resonant capacitors connected in series with the autotransformer windings constitute a high-frequency resonant tank. At the same time, the resonant capacitors block the DC-bias current of the autotransformer. The resonant operation with a sinusoidal current of the main switch and diodes enables electromagnetic interference mitigation and improves the efficiency of the converter. Experimental results of a 100 W, 30 V/200 V prototype are presented to verify the analysis results of the proposed converter.

  • Non-Linear Analysis of Inter-Story Pounding between Wood-Framed Buildings during Ground Motion
    • Wojciech Migda
    • Marcin Szczepański
    • Natalia Lasowicz
    • Anna Jakubczyk-Gałczyńska
    • Robert Jankowski
    2019 Pełny tekst Geosciences

    Pounding between adjacent buildings during ground motion may result in structural damage or lead to total destruction of structures. The research on the phenomenon has recently been much advanced; however, the analyses have been carried out only for concrete, steel, and masonry structures, while pounding between wooden buildings has not been studied so far. The aim of this paper is to show the results of detailed non-linear seismic analysis of inter-story pounding between the wood-framed buildings modelled by using the finite element method. Firstly, the modal analysis of the structures was conducted. Then, the detailed non-linear analysis of earthquake-induced collisions between two wood-framed buildings of different heights was carried out. The results of the analysis indicate that the behavior of both structures in the longitudinal as well as in the transverse direction is significantly influenced by interactions. The response of the taller building is increased in both directions. On the other hand, the response of the lower building is decreased in the longitudinal direction, while it is increased in the transverse one. The results of the study presented in the paper indicate that, due to deformability of buildings made of wood, structural interactions may change their responses much more, as compared to steel, reinforced concrete, or masonry structures.

  • Nonlinear Control of a Doubly Fed Generator Supplied by a Current Source Inverter
    • Krzysztof Blecharz
    • Marcin Morawiec
    2019 Pełny tekst ENERGIES

    Nowadays, wind turbines based on a doubly fed induction generator (DFIG) are a commonly used solution in the wind industry. The standard converter topology used in these systems is the voltage source inverter (VSI). The use of reverse-blocking insulated gate bipolar transistor (RB-IGBT) in the current source inverter topology (CSI), which is an alternative topology, opens new possibilities of control methods. This paper presents a novel power control system for a DFIG supplied by a CSI. The authors propose to use multi-scalar DFIG state variables. A nonlinear control method realized by feedback linearization was used to control the active and reactive powers of the generator. In the feedback linearization controls, the nonlinear DFIG model was taken into account. In the control system structure, classical proportional–integral controllers were used. The control variables were the output current vector components of the CSI. Such approach was named the “current control”. The proposed control method is characterized by good dynamic properties which, combined with the inverter properties in the rotor circuit, allow to increase the quality of the energy transferred to the grid by the generator. In the simulation tests, the correctness of the decoupling of the active and reactive power control loops, the dynamics of controlled power changes, and the change of the machine operating range resulting from the increase of the rotational speed of the generator shaft were controlled. The simulation studies also evaluated the impact of changes in the value of the passive elements of the system on the operation of the generator system. Characteristic operating states of the generator system were analyzed using computer simulations.

  • Nonlinear finite element modeling of vibration control of plane rod-type structural members with integrated piezoelectric patches
    • Jacek Chróścielewski
    • Rüdiger Schmidt
    • Victor Eremeev
    2019 Pełny tekst CONTINUUM MECHANICS AND THERMODYNAMICS

    This paper addresses modeling and finite element analysis of the transient large-amplitude vibration response of thin rod-type structures (e.g., plane curved beams, arches, ring shells) and its control by integrated piezoelectric layers. A geometrically nonlinear finite beam element for the analysis of piezolaminated structures is developed that is based on the Bernoulli hypothesis and the assumptions of small strains and finite rotations of the normal. The finite element model can be applied to static, stability, and transient analysis of smart structures consisting of a master structure and integrated piezoelectric actuator layers or patches attached to the upper and lower surfaces. Two problems are studied extensively: (i) FE analyses of a clamped semicircular ring shell that has been used as a benchmark problem for linear vibration control in several recent papers are critically reviewed and extended to account for the effects of structural nonlinearity and (ii) a smart circular arch subjected to a hydrostatic pressure load is investigated statically and dynamically in order to study the shift of bifurcation and limit points, eigenfrequencies, and eigenvectors, as well as vibration control for loading conditions which may lead to dynamic loss of stability.

  • Nonlinear Interaction of Modes in a Planar Flow of a Gas with Viscous and Thermal Attenuation
    • Anna Perelomova
    2019 Pełny tekst Archives of Acoustics

    The nonlinear interaction of wave and non-wave modes in a gas planar flow are considered. Attention is mainly paid to the case when one sound mode is dominant and excites the counter-propagating sound mode and the entropy mode. The modes are determined by links between perturbations of pressure, density, and fluid velocity. This definition follows from the linear conservation equations in the differential form and thermodynamic equations of state. The leading order system of coupling equations for interacting modes is derived. It consists of diffusion inhomogeneous equations. The main aim of this study is to identify the principle features of the interaction and to establish individual contributions of attenuation (mechanical and thermal attenuation) in the solution to the system

  • NON-LINEAR MASTIC CHARACTERISTICS BASED ON THE MODIFIED MSCR (MULTIPLE STRESS CREEP RECOVERY) TEST
    • Grzegorz Mazurek
    • Marek Pszczoła
    • Cezary Szydłowski
    2019 Pełny tekst Structure and Environment

    Mastic containing asphalt in its composition is an example of a viscoelastic material. It is an effective binder in asphalt. It consists of a filler (<0.063 mm) and asphalt mixed in the right proportions. Just like in asphalt, its response depends on the temperature level, the load and stress time. Changing the stress stiffness of the mastic affects the non-linear course of the stress-strain relationship. Modelling of the non-linear course of the mastic response for any stress history was performed using a single-integral Schapery equation. Two mastic composites made using filler to asphalt 2:1 ratio, was used in the tests. In addition, the contents of the filler, in one of the compositions, was enriched with hydrated lime in an amount of 15% in relation to the mass of the lime filler. It was found that the use of non-linear viscoelasticity model describes, in a comprehensive manner, the change in strain over time with different stress histories. In addition, hydrated lime reduced strains in the mastic compared to a composition consisting of limestone dust only.

  • Nonlinear planar modeling of massive taut strings travelled by a force-driven point-mass
    • Manuel Feretti
    • Serge Gavrilov
    • Victor Eremeev
    • Angelo Luongo
    2019 Pełny tekst NONLINEAR DYNAMICS

    The planar response of horizontal massive taut strings, travelled by a heavy point-mass, either driven by an assigned force, or moving with an assigned law, is studied. A kinematically exact model is derived for the free boundary problem via a variational approach, accounting for the singularity in the slope of the deflected string. Reactive forces exchanged between the point-mass and the string are taken into account via Lagrange multipliers. The exact model is consistently simplified via asymptotic analysis, which leads to condense the horizontal displacement as a passive variable. The dynamic increment of tension, with respect the static one, is neglected in the governing equations, but evaluated a posteriori, as a higher-order quantity in a perturbation perspective. The equations are solved and rearranged in the form of an integral equation coupled with an integro-differential equation, thus extending a procedure already introduced in the literature. Numerical results, showing the importance of the horizontal reactive force on the quality of motion, are discussed, generalizing those relevant to massless strings.

  • Nośność stalowych słupów złożonych z kształtowników giętych na zimno o przekroju poprzecznym otwartym z dodatkowymi gałęziami przylgowymi.
    • Patryk Deniziak
    2019 Pełny tekst

    W niniejszej pracy opisano zagadnienie wzajemnej współpracy gałęzi przylgowo złożonego słupa wykonanego z kształtowników wykonanych w technologii gięcia na zimno. Przedstawiono proces przygotowania eksperymentu laboratoryjnego wykonanego w skali naturalnej, przebieg badań oraz sposób wykonania modelu numerycznego w programie Abaqus. Wyniki analizy numerycznej porównano z wynikami eksperymentu. Na tej podstawie dokonano walidacji modelu numerycznego. Przeprowadzono także obliczenia parametryczne wykraczające poza zakres ograniczony eksperymentem. Pracę wieńczy rozdział, w którym przedstawiono wnioski i podsumowanie rezultatów pracy. Przedstawiono także kierunki dalszych badań.

  • Novel bio-based thermoplastic poly(ether-urethane)s. Correlations between the structure, processing and properties
    • Paulina Kasprzyk
    • Janusz Datta
    2019 POLYMER

    The main purpose of this work was to analyze the effect of the number of unreacted isocyanate groups and the [NCO]/[OH] molar ratio during the chain extension of a prepolymer during the polymerization process on the structure, processing and selected properties of thermoplastic poly(ether-urethane)s. Three series of novel thermoplastic polyurethanes were obtained via a prepolymer route. Three prepolymers were synthesized from diisocyanate and bio-based polyol, which contained 6, 7 and 8% of unreacted isocyanate groups. The prepolymer chains were extended by using bio-based 1,4-butanediol with four different [NCO]/[OH] molar ratios. It was confirmed that the concentration of unreacted isocyanate groups in the prepolymer has an effect on the degree of the hard segment phase separation of poly(ether-urethane)s. It was also found that the melt flow index has a significant impact on the processing of polyurethanes which can be correlated to the chemical structure and dynamic mechanical properties of the polyurethanes.

  • Novel Coplanar-Strip-Based Excitation Technique for Design of Broadband Circularly Polarization Antennas with Wide 3-dB Axial Ratio Beamwidth
    • Ullah Ubaid
    • Sławomir Kozieł
    2019 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION

    In this paper, a novel excitation technique for design of a single-point-fed compact low-profile wide-slot antennas with broadband circular polarization (CP) and wide 3 dB axial ratio (AR) beamwidth is presented. Two inverted L-shape parasitic strips placed coplanar to the microstrip line of an asymmetric CPW, and a horizontal strip that protrudes from the vertical edge of the backside ground plane of the substrate are used for CP excitation. The overall footprint of the structure is only Ls × Ws = 0.3 λ0 × 0.28 λ0 when measured at the lowest operating frequency. The antenna prototype has been validated experimentally. The measured results indicate that a wide impedance bandwidth of 72% (2.26 GHz-4.85 GHz) and a CP bandwidth of 66% (2.44 GHz- 4.87 GHz) can be achieved. In addition to the wideband characteristics in terms of the impedance bandwidth and CP, a stable bidirectional radiation pattern with a wide 3 dB beamwidth of 85° ± 5° is obtained for 58% of the total CP bandwidth without involving any complex circuitry. Furthermore, by placing a flat metallic reflector behind the antenna, a unidirectional radiation pattern is produced without changing the geometrical dimensions of the proposed antenna. The average realized gain of the antenna without a reflector is 3.3 dBi, whereas it increases up to 6.3 dBi with the substrate-size reflector.

  • Novel steroid sulfatase inhibitors based on N ‐thiophosphorylated 3‐(4‐aminophenyl)‐coumarin‐7‐O‐sulfamates
    • Mateusz Daśko
    • Sebastian Demkowicz
    • Karol Biernacki
    • Amira Harrous
    • Janusz Rachoń
    • Witold Kozak
    • Aleksandra Martyna
    • Maciej Masłyk
    • Konrad Kubiński
    • Anna Boguszewska‐Czubara
    2019 Pełny tekst DRUG DEVELOPMENT RESEARCH

    In the present work, we described convenient methods for the synthesis ofN-thiophosphorylated 3-(4-aminophenyl)-coumarin-7-O-sulfamates as steroid sulfatase(STS) inhibitors. To design the structures of the potential STS inhibitors, molecularmodeling techniques were used. A computational docking method was used to deter-mine the binding modes of the synthesized inhibitors as well as to identify potentialinteractions between specified functional groups on the inhibitors and the amino acidresidues present in the active site of the enzyme. The inhibitory activities of the syn-thesized compounds were tested in an enzymatic assay with STS isolated from ahuman placenta. Within the set of newly synthesized compounds,9edemonstratedthe highest inhibitory activity in the enzymatic assay with an IC50value of 0.201μM(the IC50value of667-COUMATEin the same test was 0.062μM). Furthermore, wetried to verify if the obtained STS inhibitors are able to pass through the cellular mem-brane effectively in cell line experiments. In the course of our study, we determinedthe STS activity in the MCF-7 cell line after incubation in the presence of the inhibitors(at 100 nM concentration). For this evaluation, we included newly synthesized com-pounds9a-gand theirN-phosphorylated analogs6a-h, whose synthesis has been pre-viously described. We found that the lowest STS activities were measured in thepresence ofN-phosphorylated derivatives6e(0.1% of STS activity) and6f(0.2% ofSTS activity). The measured STS activity in the presence of667-COUMATE(used as areference) was 0.1%. Moreover, at concentrations up to 1μM, the most active com-pounds (6e,6f,9b,and9e) did not exert any toxic effects on zebrafish embryos.

  • Novel therapeutic compound acridine–retrotuftsin action on biological forms of melanoma and neuroblastoma
    • Miroslawa Cichorek
    • Anna Ronowska
    • Monika Gensicka-Kowalewska
    • Milena Deptula
    • Iwona Pelikant-Malecka
    • Krystyna Dzierzbicka
    2019 Pełny tekst JOURNAL OF CANCER RESEARCH AND CLINICAL ONCOLOGY

    PURPOSE: As a continuation of our search for anticancer agents, we have synthesized a new acridine-retrotuftsin analog HClx9-[Arg(NO2)-Pro-Lys-Thr-OCH3]-1-nitroacridine (named ART) and have evaluated its activity against melanoma and neuroblastoma lines. Both tumors develop from cells (melanocytes, neurons) of neuroectodermal origin, and both are tumors with high heterogeneity and unsatisfactory susceptibility to chemotherapies. Thus, we analyzed the action of ART on pairs of biological forms of melanoma (amelanotic and melanotic) and neuroblastoma (dopaminergic and cholinergic) with regard to proliferation, mechanism of cell death, and effect on the activity of tricarboxylic acid cycle (TAC) enzymes. METHODS: The cytotoxicity of ART was evaluated by XTT and trypan blue tests. Cell death was estimated by plasma membrane structure changes (phosphatidylserine and calreticulin externalization), caspase activation, presence of ROS (reactive oxygen species), activity of tricarboxylic acid cycle enzymes (pyruvate dehydrogenase complex, aconitase, and isocitrate dehydrogenase), NAD level, and ATP level. RESULTS: ART influences the biological forms of melanoma and neuroblastoma in different ways. Amelanotic (Ab) melanoma (with the inhibited melanogenesis, higher malignancy) and SHSY5Y neuroblastoma (with cholinergic DC cells) were especially sensitive to ART action. The Ab melanoma cells died through apoptosis, while, with SH-SY5Y-DC neuroblastoma, the number of cells decreased but not as a result of apoptosis. With Ab melanoma and SH-SY5Y-DC cells, a diminished activity of TAC enzymes was noticed, along with ATP/NAD depletion. CONCLUSION: Our data show that the biological forms of certain tumors responded in different ways to the action of ART. As a combination of retrotuftsin and acridine, the compound can be an inducer of apoptotic cell death of melanoma, especially the amelanotic form. Although the mechanism of the interrelationships between energy metabolism and cell death is not fully understood, interference of ART with TAC enzymes could encourage the further investigation of its anticancer action.

  • Nowa koncepcja poprawy elastyczności bloków parowych z zastosowaniem magazynów pary
    • Janusz Badur
    • Paweł Ziółkowski
    2019 INPE: Informacje o Normach i Przepisach Elektrycznych

    Celem niniejszej pracy jest krótki przegląd sposobów magazynowania energii i odniesienie się do sposobu, który byłby najdogodniejszy dla bloków parowych klasy 370-390 MWe. W niniejszej pracy zaproponowano innowacyjny magazyn pary, który jest integralną częścią obiegu parowego i dzięki temu szybko odpowiada na zmiany zapotrzebowania na energię elektryczną, a zatem może usprawniać świadczenia usługi regulacji pierwotnej przy jednoczesnym zachowaniu wysokiej sprawności konwersji energii. W odniesieniu do bloków energetyki zawodowej poprawia bezpieczeństwo pracy jednostek wytwórczych, gdyż zapobiega przeciążaniu termicznemu kotłów i turbin w przypadku wysokiego zejście z mocą lub w przypadku gwałtownych najazdów. Elektrownia parowa dostosowana do szybkich zmian mocy staje się bardziej konkurencyjna na rynku mocy poprzez poprawę charakterystyki dynamicznej.

  • NOWE MATERIAŁY ANODOWE DLA TLENKOWYCH OGNIW PALIWOWYCH (SOFCs) ZAPEWNIAJĄCE WYDAJNĄ PRACĘ W SYSTEMACH ZASILANYCH BIOGAZEM.
    • Patryk Błaszczak
    2019

    Tlenkowe ogniwa paliwowe (z ang. Solid Oxide Fuel Cells, SOFCs) zasilane paliwami innymi niż czysty wodór podlegają procesom szybszego niszczenia i utraty zdolności do generowania prądu. Głównymi przyczynami takiego zachowania jest osadzanie się węgla na powierzchni anody oraz zatruwanie materiałów ceramicznych śladowymi ilościami siarki, fosforu lub chloru w paliwach węglowodorowych. W niniejszej pracy dokonano przeglądu przez wybrane metody modyfikowania materiałów oraz struktury SOFC w celu poprawy wydajności ogniw zasilanych biogazem. Najnowsze badania dowodzą, że stosowanie warstw ochronnych opartych o tlenek ceru (CeO2) mogą może mieć korzystny wpływ na jakość działania ogniw paliwowych. Dodatkowo szereg materiałów wykazujących zdolność do tzw. eksolucji może zastąpić szeroko stosowany cermet Ni-YSZ. Materiały te są bardziej odporne na zatruwanie siarką, wspomagają usuwanie nagromadzeń węgla oraz stanowią doskonały materiał katalityczny po wprowadzeniu metali aktywnych takich jak Ni, Cu, Fe lub Co.

  • Nowe substancje psychoaktywne - nowe wyzwania analityczne
    • Laura Banaszkiewicz
    • Mateusz Kacper Woźniak
    • Marek Biziuk
    • Jacek Namieśnik
    2019 Pełny tekst Analityka: Nauka i Praktyka

    Nowe substancje psychoaktywne stanowią poważny problem ekonomiczno-społeczny i zdrowotny ze względu na swoje właściwości psychoaktywne oraz uzależniające. Niejednokrotnie zdarza się, że właściwości fizykochemiczne oraz wpływ na organizm człowieka związków z grupy NPS nie są zbadane zanim trafią do nielegalnego obrotu. Wśród substancji należących do NPS wyróżnia się takie grupy chemiczne jak: syntetyczne kannabinoidy, katynony, piperazyny, tryptaminy, fenyloetyloaminy, fentanyle inne. Każdego roku syntezowane są kolejne związki, co utrudnia ich oznaczanie na potrzeby analiz chemiczno-toksykologicznych. Różnorodność tych substancji implikuje konieczność opracowywania nowych procedur ich oznaczania. Obecnie, najczęściej wykorzystywaną techniką do oznaczania związków z grupy NPS w próbkach o złożonym składzie matrycy jest chromatografia cieczowa sprzężona z tandemową spektrometrią mas (LC-MS/MS), a na etapie przygotowania próbek coraz częściej stosuje się nowe metody ekstrakcji oparte na zasadach zielonej chemii analitycznej. W pracy dokonano przeglądu aktualnie używanych procedur oznaczania związków z grupy NPS (głównie syntetycznych katynonów i kannabinoidów, które są nadal najczęściej spotykanymi substancjami psychoaktywnymi) wraz z ich parametrami walidacyjnymi. Skupiono się na danych literaturowych z lat 2016-2018.

  • N-phosphonomethylglycine utilization by the psychrotolerant yeast Solicoccozyma terricola M 3.1.4.
    • Natalia Stosiek
    • Agata Terebieniec
    • Adam Ząbek
    • Młynarz Piotr
    • Hubert Cieśliński
    • Magdalena Klimek-Ochab
    2019 Pełny tekst BIOORGANIC CHEMISTRY

    SolicoccozymaterricolaM 3.1.4., the yeast strain isolated from soil sample from blueberry cultivation in MiedzyrzecPodlaski in Poland, is capable to split of phosphorus to nitrogen and nitrogen to carbon bonds inN-phosphono-methylglycine (PMG, glyphosate). The biodegradation process proceeds in the phosphate-independent manner. Itis the first example of a psychrotolerant yeast strain able to degrade PMGviaCeN bond cleavage accompanied byAMPA formation and not like in most microorganismsviaCeP bond disruption followed by the sarcosine pathway.Glyphosate oxidoreductase (GOX) type activity was detected in cell-free extracts prepared fromS.terricolaM 3.1.4.pregrown on 4 mM PMG as a sole phosphorus and nitrogen source in cultivation medium

  • Numerical Analysis of an Impact of Planned Location of Sewage Discharge on Natura 2000 Areas – The Dead Vistula Region Case Study
    • Piotr Zima
    2019 Pełny tekst Polish Maritime Research

    This article presents results of an analysis of impact of a designed discharge of contaminated water into the Dead Vistula (Wisła Martwa) in the region of the Isthmus (Przesmyk) with the aim of determination of a possible effect of the pollution onto protected areas of Natura 2000 (bird habitats and sites, especially the Bird Paradise – Ptasi Raj) nature reserve. The analysis was conducted on the basis of the two-dimensional modelling of unsteady transport of non-degradable dissolved matter. To this end, a numerical model of a section of the Dead Vistula was worked out. Four scenarios of hydro-dynamical conditions (2 – for average weather conditions and 2 – for stormy weather conditions) were selected. To solving the equation of pollution migration the finite volumes method (MOS) was applied. Two localizations of contaminated water discharge outlet were considered, namely: the first from the side of Siennicki Bridge before the Isthmus and the other in the section of the Brave Vistula (Wisła Śmiała) downstream the Isthmus. The obtained results made it possible to assess positively the first localization of the designed discharge outlet. In the other case there is a fear that at unfavourable hydro-meteorological conditions a water pollution may happen over Natura 2000 protected areas.

  • Numerical Analysis of Recharge Rates and Contaminant Travel Time in Layered Unsaturated Soils
    • Adam Szymkiewicz
    • Julien Savard
    • Beata Jaworska-Szulc
    2019 Pełny tekst Water

    This study focused on the estimation of groundwater recharge rates and travel time of conservative contaminants between ground surface and aquifer. Numerical simulations of transient water flow and solute transport were performed using the SWAP computer program for 10 layered soil profiles, composed of materials ranging from gravel to clay. In particular, sensitivity of the results to the thickness and position of weakly permeable soil layers was carried out. Daily weather data set from Gda´nsk (northern Poland) was used as the boundary condition. Two types of cover were considered, bare soil and grass, simulated with dynamic growth model. The results obtained with unsteady flow and transport model were compared with simpler methods for travel time estimation, based on the assumptions of steady flow and purely advective transport. The simplified methods were in reasonably good agreement with the transient modelling approach for coarse textured soils but tended to overestimate the travel time if a layer of fine textured soil was present near the surface. Thus, care should be taken when using the simplified methods to estimate vadose zone travel time and vulnerability of the underlying aquifers.

  • Numerical analysis of size effect in RC beams scaled along height or length using elasto-plastic-damage model enhanced by non-local softening.
    • Ireneusz Marzec
    • Andrzej Tejchman-Konarzewski
    • Zenon Mróz
    2019 Pełny tekst FINITE ELEMENTS IN ANALYSIS AND DESIGN

    Artykuł omawia wyniki numeryczne dotyczące efektu skali w belkach żelbetowych uzyskane stosując metodę elementów skończonych. Dwuwymiarowe obliczenia wykonano dla belek żelbetowych podczas 4-punktowego zginania. Belki były skalowane wzdłuż wysokości lub długości. Beton został opisany prawem sprężysto-plastycznym z degradacją sztywności, rozszerzonym o nielokalność w osłabieniu. Wyniki numeryczne zostały porównane z wynikami doświadczalnymi. Uzyskano bardzo dobrą zgodność między wynikami numerycznymi i doświadczalnymi.

  • Numerical Analysis of TB32 Crash Tests for 4-cable Guardrail Barrier System Installed on the Horizontal Convex Curves of Road
    • Krzysztof Wilde
    • Dawid Bruski
    • Marcin Budzyński
    • Stanisław Burzyński
    • Jacek Chróścielewski
    • Kazimierz Jamroz
    • Łukasz Pachocki
    • Wojciech Witkowski
    2019 Pełny tekst INTERNATIONAL JOURNAL OF NONLINEAR SCIENCES AND NUMERICAL SIMULATION

    Horizontal curves are one of the elements of road infrastructure where statistically a relatively high number of accidents have been reported. In the last ten years in Poland approx. 10% of all road accidents happened on horizontal curves of roads and was responsible for approx. 14% of all fatalities on Polish roads. Thus, this issue is important and requires extensive research and proper road safety treatments. One possible measure that may contribute to improvement of safety on road curves may be barriers. The purpose of this work is to assess, with use of numerical simulations, the performance of the 4-cable barrier systems installed on horizontal road convex curves. The most important parameters for road safety barriers are presented including the effect of various impact velocities and the radiuses of the road curves.

  • Numerical analysis of the container vessel's self-propulsion at different rudder deflection angles
    • Radosław Kołodziej
    • Wawrzusiszyn Michał
    • Bielicki Sebastian
    2019

    Nowadays, CFD becomes one of the most commonly used research method in ship hydrodynamics, limited to the analyses of hull resistance in calm water. With continuously improving computing power and increasingly more accurate numerical methods it is possible to simulate more complex cases. State of the art CFD tools also enable development of new ways of assessing ship maneuvering performance. This paper presents an attempt on using CFD for evaluation of the coefficients used in the formulation of rudder forces applied in the ship manoeuvring model. These coefficient are normally evaluated in captive tests of the hull with working propeller and rudder deflected at different angles; the paper presents the results of CFD simulation of this kind of experiment. The test case used in the analyses is the well known the KRISO Container Ship (KCS). The computations were carried out at model scale 1:50, for which the reference model test results are available. Comparison of CFD and experimental results is presented.

  • Numerical investigation of multiphase blood flow coupled with lumped parameter model of outflow
    • Bartłomiej Melka
    • Wojciech Adamczyk
    • Marek Rojczyk
    • Marcin Nowak
    • Maria Gracka
    • Andrzej J. Nowak
    • Adam Golda
    • Ryszard Białecki
    • Ziemowit Ostrowski
    2019 INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW

    Purpose The purpose of this paper is the application of the computational fluid dynamics model simulating the blood flow within the aorta of an eight-year-old patient with Coarctation of Aorta. Design/methodology/approach The numerical model, based on commercial code ANSYS Fluent, was built using the multifluid Euler–Euler approach with the interaction between the phases described by the kinetic theory of granular flow (KTGF). Findings A model of the blood flow in the arches of the main aorta branches has been presented. The model was built using the multifluid Euler–Euler approach with the interaction between the phases described by the KTGF. The flow and pressure patterns, as well as the volumetric concentration of the blood components, were calculated. The lumped parameter model was implemented to couple the interaction of the computational domain with the remaining portion of the vascular bed. Originality/value The multiphase model based on the Euler–Euler approach describing blood flow in the branched large vessel with a three-element Windkessel model in the coarcted geometry was not previously described in the literature.

  • Numerical investigation of the core eccentricity effect on wave propagation in embedded waveguide
    • Beata Zima
    • Rafał Kędra
    2019 Pełny tekst Diagnostyka

    The paper presents results of theoretical and numerical investigation of guided wave propagation in two-layer bars with geometric imperfections in the form of eccentric location of steel core. Steel rod of diameter equal to 1 cm embedded in composite mortar-type cover with external diameter equal to 5 cm has been taken into consideration. Several different rods with variable size of eccentricity are analysed. Results for rods with misalignment of the cover and the core are presented as dispersion curves which were calculated using SAFE method (semi-analytical finite element) and compared with results obtained for perfect axisymmetric rod. Moreover, numerical calculation for several cases of imperfect rods were conducted and results given in the form of displacements and accelerations maps and time-domain signals.

  • Numerical investigation on dynamic response of a steel lattice tower under various seismic events
    • Tomasz Falborski
    • Natalia Lasowicz
    2019

    The present paper presents the results of the numerical study designed to investigate the soil-structure flexibility effects on modal parameters (i.e. fundamental frequencies) and time-history analysis response (represented by the top relative displacements) of a 46.8 m high steel lattice tower subjected to a number of ground motions including also one mining tremor. In addition to the fixed-base condition, three different soil types (i.e. dense soil, stiff soil, and soft soil) were considered in this investigation. Site conditions were characterized by their average effective profile velocities, Poisson’s ratios, and finally mass densities. Soil-foundation flexibility was introduced using the spring-based approach, utilizing foundation springs and dashpots. The first step was to investigate the influence of different base conditions on modal parameters of the steel lattice tower. In the final part of the current study time-history analysis was performed using different two-component ground motion records (in two horizontal, mutually perpendicular directions). The results obtained indicate that modal parameters and dynamic response of the structure may be considerably affected by the soil-structure interaction effects. Therefore, the present paper confirms the necessity of utilizing soil-flexibility into numerical research.

  • Numerical investigation on the performance of a small counter-rotating wind turbine
    • Michał Pacholczyk
    • Krzysztof Blecharz
    • Dariusz Karkosiński
    2019 Pełny tekst E3S Web of Conferences

    The article presents the results of the investigation on the performance of a small counter-rotating wind turbine. The wind turbine has been simulated using Computational Fluid Dynamics methods. Actuator Line Model has been successfully used to represent rotors in the computational domain. A parametric study has been carried out, taking into account changes in the tip speed ratio of the rotors while maintaining a constant distance between upwind and downwind rotor. Study results revealed a noticeable increase in power coefficient for optimal configuration. Dynamic interaction between rotors has been investigated exposing no significant interference in both torque and power.

  • Numerical modeling and experimental validation of full-scale segment to support design of novel GFRP footbridge
    • Jacek Chróścielewski
    • Tomasz Ferenc
    • Tomasz Mikulski
    • Mikołaj Miśkiewicz
    • Łukasz Pyrzowski
    2019 Pełny tekst COMPOSITE STRUCTURES

    The paper contains analysis of full-scaled three meters long segment of a novel composite footbridge. Both numerical modeling and experimental validation were performed. Analyzed object is a shell type sandwich channel-like structure made of composite sandwich with GFRP laminates as a skin and PET foam as a core. Several static load schemes were performed including vertical and horizontal forces. In FEM analysis multilayered laminate was modeled by means of Equivalent Single Layer (ESL) method while the foam was assumed as three-dimensional continuum. Results were compared with the ones obtained from experiments. Good agreement in comparison showed the correctness of conducted assumption what was a great support in designing process of fourteen-and-half meters long footbridge.

  • Numerical modeling of exciton impact in two crystalographic phases of the organo-lead halide perovskite (CH3NH3PbI3) solar cell
    • Damian Głowienka
    • Jędrzej Szmytkowski
    2019 Pełny tekst SEMICONDUCTOR SCIENCE AND TECHNOLOGY

    To improve the power conversion efficiency of solar cells based on organo–lead halide perovskites, a detailed understanding of the device physics is fundamental. Here, a computational analysis of excitons impact is reported for these types of photocell. Numerical calculations based on the model, which take into account electronic charge carriers (electrons and holes), excitons and ions, have been carried out. The role of excitons in two crystallographic phases associated with different temperatures (80 K and 295 K) have been studied with the Saha relation, which clearly distinguishes a domination of free charge carriers or excitons. We have confirmed that excitons prevail in the orthorombic phase. Our work provides information about the photophysics of the lead halide perovskite, which allows for a better understanding of the operation of devices based on perovskite materials.

  • Numerical Modelling of Shear Localization in Granular Bodies using MPM and Non-local Hypoplasticity
    • Jakub Krzyżanowski
    • Michał Wójcik
    • Andrzej Tejchman-Konarzewski
    2019 Pełny tekst AIP Conference Proceedings

    The paper deals with modelling of shear localization in granular bodies by means of an enhanced hypoplastic constitutive model and material point method (MPM). The calculations were carried out for plane strain compression of non-cohesive sand. In order to properly capture the width and inclination of shear zones, the constitutive model was enriched by a characteristic length of micro-structure by means of a non-local theory. The approach offered a good correspondence between numerical results and experimental ones.

  • NUMERICAL SIMULATIONS OF HONING PROCESS OF THIN WALL CYLINDER LINERS, WITH CONSTANT AND WITH VARIABLE THICKNESS OF WALL OF HONED PARTS
    • Piotr Sender
    2019

    Numerical simulations of honing process of thin-wall cylinder liners, with constant and with variable thickness of the wall of honed workpieces can improve and can help to conduct the experimental research of honing process and can improve the honing process. A very valuable research assumption, before performing the numerical analysis of computer simulation of honing process, is the measurement of the real geometry of the honing head using a CNC coordinate measuring machine and measuring of the honed workpiece’s temperature occurring in the honed workpiece during honing process with a thermal infrared camera. Thick-walled workpieces do not create machining and technological performance problems. In a predictable way, it’s possible to plan the machining time remaining to receive the desired diameter of the hole being honed. Deformations of a thin-walled workpiece with varying wall thickness occurring during honing, which were measured after machining, showed that there is no linear correlation of holes deformation received for a different crosssection thicknesses of wall of honed cylinder liners for various oilstone pressure and due to the workpiece temperature increase.

  • Numerical simulations of overflow experiments on a model dike
    • Witold Tisler
    • Wioletta Gorczewska-Langner
    • Rafał Ossowski
    • Marcin Cudny
    • Adam Szymkiewicz
    2019 Pełny tekst MATEC Web of Conferences

    Dike failure due to overtopping is one of the important factors, which should be considered in the dike designing process. Although the overflow is characterized by the relatively low risk of occurrence, in many cases dikes are totally destroyed or seriously damaged. An interesting phenomenon occurring during overflow is the trapping of air in pores of the unsaturated soil material. As the infiltration progresses from all sides, the air pressure in the unsaturated region increases, which may ultimately lead to damage of the dike structure. It happens when the air is expulsed in form of bursts and forms large macropores. Such a behaviour evidenced in laboratory experiments. In this study we attempt to simulate the evolution of stress field in the model dike subjected to overtopping. The results are in qualitative agreement with observations, showing that formation of the first macropores occurs in the direction perpendicular to the minor principal stress in the soil mass along the dike slope edge.

  • Numerical Study on Mitigation of Flow Maldistribution in Parallel Microchannel Heat Sink: Channels Variable Width Versus Variable Height Approach
    • Ritunesh Kumar
    • Gurjeet Singh
    • Dariusz Mikielewicz
    2019 JOURNAL OF ELECTRONIC PACKAGING

    Microchannel heat sink on one hand enjoys benefits of intensified several folds heat transfer performance but on the other hand has to suffer aggravated form of trifling limitations associated with imperfect hydrodynamics and heat transfer behavior. Flow maldistribution is one of such limitation that exaggerates temperature nonuniformity across parallel microchannels leading to increase in maximum base temperature. Recently, variable width channels approach had been proposed by the current authors to mitigate the flow maldistribution in parallel microchannels heat sinks (MCHS), and in the current numerical study, variable height approach is opted for flow maldistribution mitigation. It is found that variable height microchannels heat sinks (VHMCHS) approach mitigates flow maldistribution rapidly in comparison to variable width microchannels heat sinks (VWMCHS) approach, almost 50% computational time can be saved by VHMCHS approach. Average fluid-solid interface temperature fluctuation across parallel microchannels reduces 3.3 degrees C by VHMCHS in comparison to VWMCHS approach. The maximum and average temperatures of the base of the heat sink are further reduced by 5.1 degrees C and 2.7 degrees C, respectively, for the VHMCHS. It is found that overall heat transfer performance of the heat sink improves further by 3.8% and 5.1% for the VWMCHS and VHMCHS, respectively. The pressure drop penalty of the VHMCHS is found to be 7.2% higher than VWMCHS.

  • Numerically efficient algorithm for compact microwave device optimization with flexible sensitivity updating scheme
    • Anna Pietrenko-Dąbrowska
    • Sławomir Kozieł
    2019 Pełny tekst INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING

    An efficient trust-region algorithm with flexible sensitivity updating management scheme for electromagnetic (EM)-driven design optimization of compact microwave components is proposed. During the optimization process, updating of selected columns of the circuit response Jacobian is performed using a rank-one Broyden formula (BF) replacing finite differentiation (FD). The FD update is omitted for directions sufficiently well aligned with the recent design relocation. As the algorithm converges, the alignment threshold is gradually reduced so that the condition for using BF becomes less stringent. This allows for further reduction of the number of EM simulations involved in the optimization process. The presented flexible Jacobian update scheme allows for considerable reduction of the computational cost with only slight degradation of the design quality. Robustness of the presented algorithm is validated through multiple optimization runs from random initial designs. The verification experiments are conducted for a range of microwave components, including a compact microstrip coupler as well as a threesection compact microwave resonant cell-based impedance transformer. The effects of the alignment threshold value on the computational efficiency of the algorithm and the design quality are investigated. Significant savings reaching 50% as compared to the reference algorithm are demonstrated.

  • Nutrient loss from three small-size watersheds in the southern Baltic Sea in relation to agricultural practices and policy
    • Ewa Wojciechowska
    • Stefan Pietrzak
    • Karolina Matej-Łukowicz
    • Nicole Nawrot
    • Piotr Zima
    • Dominika Kalinowska
    • Paweł Wielgat
    • Hanna Obarska-Pempkowiak
    • Magdalena Gajewska
    • Grażyna Dembska
    • Paweł Jasiński
    • Grażyna Pazikowska-sapota
    • Katarzyna Galer-Tatarowicz
    • Lidia Dzierzbicka-Głowacka
    2019 Pełny tekst JOURNAL OF ENVIRONMENTAL MANAGEMENT

    Agriculture is the major contributor of waterborne nutrient fluxes into the Baltic Sea, one of the world’s most eutrophication-sensitive areas. Poland, as a large, densely populated state ohf the Baltic Region, with dominating agricultural land use, largely contributes to riverborne loads of N and P. The aim of our study was to examine the input of nutrients from three small first-order agricultural watersheds (Bladzikowski Stream, Gizdepka river and Mrzezino canal) in the Pomerania region, into the Bay of Puck, inner part of the Gulf of Gdansk. This study attempts to give a partial answer as to the question if inputs of nutrients from the 3 analysed watersheds comply with the targets of the Baltic Sea Action Plan (BSAP) and Country Allocated Reduction Targets (CART). The impact of agricultural practices was assessed on the basis of farm questionnaires and calculations of nutrient balances for the examined farms. The nutrient concentrations in the soil and drainage ditches were examined, followed by an assessment of nutrient concentrations in the watercourses at the sampling points located close to the estuaries. The average mineral N fertiliser consumption (109 kg N/ha) in the analysed watersheds was higher than Poland’s average. The average N and P surpluses for surveyed farms (96.4 kg/ha and 4.4 kg/ha, respectively) were higher than the EU mean in case of N and markedly lower in case of P. We used Principal Component Analysis which confirmed that there were correlations between nutrient surpluses and nutrient concentrations in streams and/or drainage ditches. The N-NO3 and Pmin concentrations were also correlated to precipitation. The average N concentrations in the analysed watercourses were equal to 1.53 mg/L for Gizdepka, 1.88 mg/L for Mrzezino canal and 3.52 mg/L for Bładzikowski Stream. The mean P concentrations observed in the investigated watercourses were markedly higher than 0.1 mg/L. With regard to BSAP objectives, as well as CART set for Poland, the average nutrient concentrations in rivers should be approximately at the level of 2.5 mg N/L and 0.07 mg P/L.

  • Obliczanie prądów w przewodach odgromowych w linii napowietrzno-kablowej
    • Jacek Klucznik
    • Krzysztof Dobrzyński
    2019 Pełny tekst Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

    W referacie analizowana jest linia napowietrzno-kablowa 110 kV. Referat prezentuje wpływ sposobu uziemiania żył powrotnych kabla WN na wartości prądów przy zwarciach jednofazowych, ze szczególnym uwzględnieniem prądów płynących w przewodach odgromowych linii napowietrznej. Wykazano, że dobór przewodów odgromowych linii napowietrznej powinien uwzględniać nie tylko parametry odcinka linii kablowej, ale także sposób uziemienia żył powrotnych.

  • obraz olejny 160x360 cm / bez tytułu
    • Jan Buczkowski
    2019

    Wielkogabarytowy obraz olejny

  • obraz olejny 75x95 / bez tytułu
    • Jan Buczkowski
    2019

    obraz olejny o wym. 75x90 cm

  • obraz olejny, bez tytułu, 30cm x 40cm
    • Edyta Urwanowicz
    2019

    Obraz olejny prezentowany na indywidualnej wystawie w Galerii Pionova w Gdańsku.

  • OBRONA SIECI INFORMACJOCENTRYCZNEJ PRZED ZATRUWANIEM TREŚCI PRZEZ NIEZAUFANYCH WYDAWCÓW Z UŻYCIEM MODELU INFEKCJI W GRAFACH
    • Jerzy Konorski
    • Jakub Grochowski
    2019 Pełny tekst Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

    Sieci informacjocentryczne narażone są na ataki zatruwania treści przez intruza, który przejął klucz prywatny wydawcy treści. Efektem jest podmiana treści oryginalnych na zatrute. W pracy zaproponowano model ataku opierający się na analogii z procesami infekcji w grafach i przeanalizowano prosty mechanizm obronny. Symulacje przeprowadzone w sieciach informacjocentrycz-nych o topologiach bezskalowych oraz losowych wykazały potencjalną efektywność proponowanego mechanizmu obronnego oraz wpływu liczby węzłów sąsiednich.