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Gdańsk University of Technology

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  • Impact of the trap–assisted recombination in the perovskite solar cells
    • Damian Głowienka
    • Dong Zhang
    • Mehrdad Najafi
    • Francesco Di Giacomo
    • Jędrzej Szmytkowski
    • Yulia Galagan
    2020 Full text

    To achieve the highest performance using perovskite solar cells it is necessary to understand all the dominant mechanisms which affect the operation of solar cell. Here, we have investigated the bulk and interface trap–assisted recombination processes in the solar cells with p–i–n architecture. These studies are based on the numerical and experimental methods to get better understanding of these physical processes. The following results are useful for optimization of the performance of perovskite solar cells.

  • Impact performance of novel multi-layered prepacked aggregate fibrous composites under compression and bending
    • G. Murali
    • Sallal R. Abid
    • Y.H. Mugahed Amran
    • Hakim Abdelgader
    • Roman Fediuk
    • Arikatla Susrutha
    • K. Poonguzhali
    2020 Structures

    Multi-layered Prepacked aggregate fibrous composite (MLPAFC) is a new type of concrete, which is prepared in two subsequent stages of aggregate-fibre skeleton prepacking and cementitious grouting. In this study, ten MLPAFC mixtures were prepared in three subsequent layers incorporating different contents of four different types of steel fibres. Long and short hooked-end and crimped steel fibers were adopted with 3.0 and 1.5% dosages for the outer and interior layers, respectively. In-between the three MLPAFC layers, two layers of Glass Fiber Mesh (GFM) were inserted in five of the ten mixtures. The impact response of the MLPAFC mixtures was evaluated using two test methods. In the first, the ACI 544-2R repeated free-falling weight test was followed using disk specimens, while flexural free-falling weight on prism specimens was the second adopted impact test. Moreover, Weibull distribution was used to statistically analyse the discrepancies of the obtained experimental impact records. The impact tests results revealed that MLPAFC can absorb significantly high energy under falling weight impact due to its structure and the dual crack arresting activity of both steel fibers and GFM. The cracking number of impacts of MLPAFC cylindrical specimens without GFM was increased by approximately 530–870% compared reference specimens, while increment percentages reaching 1350% were recorded at failure stage. The impact resistance of MLPAFC prisms under flexural impact was noticeably improved, yet with lower percentages than cylindrical specimens. The insertion of intermediate GFMs let to additional developments in the impact strength of both cylindrical and prism specimens.

  • Impact response of two-layered grouted aggregate fibrous concretecomposite under falling mass impact
    • M. K. Haridharan
    • S. Matheswarana
    • G. Murali
    • Sallal R. Abid
    • Roman Fediuk
    • Y.h. Mugahed Amran
    • Hakim Abdelgader
    2020 CONSTRUCTION AND BUILDING MATERIALS

    Two-layered Grouted Aggregates Fibrous Concrete Composite (TGAFCC) is a new category concrete which became popular recently and attracted the attention of researchers globally. Recent studies indicated that TGAFCC has notable improvement in mechanical properties, which has been sufficiently documented. However, the impact behaviour of TGAFCC when combined with Glass Fibre Mesh (GFM) and Textile Fibre Mesh (TFM) is still unexplored. The research objective is to study the effect of GFM and TFM insertion in TGAFCC against the drop hammer impact. Twenty one TGAFCC mixtures were prepared and divided into two series; non-fibrous concrete and fibrous concrete. The combined action of GFM and TFM of various diameters were inserted between the two layers and tested experimentally against drop mass impact. Additionally, all fibrous specimens were reinforced with a constant 3% dosage of 5D hooked end fibre. All specimens were tested under repeated drop mass impact as per ACI Committee 544. The impacts number or number of blows till the first visible crack and failure, impact energy at the first visible crack and failure, impact ductility index and cracking configuration were examined. Besides, Weibull distribution was used to examine the variations in the test results, where impact numbers were presented using the reliability function. The research findings indicate that inserting GFM and TFM between the two layers combined with 5D hooked end steel fibres, provided high impact resistance, higher absorbed energy and prolonged failure duration. Increasing the diameters of the GFM and TFM insertions, in both non-fibrous and fibrous concrete resulted in increasing the impact numbers till the first visible crack and failure. The experimental findings confirm that the major contribution of impact resistance comes from the 5D hooked end steel fibres, while the share of the intermediate meshes was significantly lower.

  • Implant system for treatment of the orbital floor defects of blowout fractures in the maxillofacial region using polypropylene yarn and bioactive bone cement
    • Marcin Wekwejt
    • Damroka Etmańska
    • Aleksandra Halman
    • Anna Pałubicka
    • Beata Świeczko-Żurek
    • Grzegorz Gajowiec
    2020 Full text JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS

    Fractures in the craniofacial region are a serious problem in terms of treatment. The most reasonable solution is the use of individual implants dedicated to a specific patient. The aim of this study was to develop the implant system specifically for treatment of the orbital floor defects of blowout fractures of maxillofacial region, using polypropylene yarn and bone cement. Three types of bone cement were used to fix the polypropylene yarn: unmodified, antibiotic‐loaded, and modified with nanometals. The following research was carried out: selection of cement production parameters, assessment of the curing time, measurement of polymerization temperature, an analysis of microstructure and surface topography, evaluation of wettability, measurement of microhardness, and studies of bactericidal effectiveness. The research confirms the possibility of using bone cement and polypropylene yarn for an individual implant, dedicated to the fractures treatment in the maxillofacial region. Moreover, the bactericidal properties of the proposed modifications for bone cement have been verified; hence, bioactive cements are recommended for use in the case of infectious complications.

  • Implementation of advanced micropollutants removal technologies in wastewater treatment plants (WWTPs) - Examples and challenges based on selected EU countries
    • Klaudia Kosek
    • Aneta Łuczkiewicz
    • Sylwia Fudala-Książek
    • Katarzyna Jankowska
    • Małgorzata Szopińska
    • Ola Svahn
    • Jens Tränckner
    • Alena Kaiser
    • Valdas Langas
    • Erland Björklund
    2020 Full text ENVIRONMENTAL SCIENCE & POLICY

    The accumulation of micropollutants (MPs) and their increasing concentration in the aquatic environment are an emerging issue for water quality in the world. The complex web of exposure pathways, as well as the variety in the chemical structure and potency of MPs, represents enormous challenges for researchers and policy initiatives. In order to manage MPs, it has to be decided which of them have to be reduced and to what extent, where in the water cycle this would be the most efficient and which technical means that should be applied to be sustainable. All of these aspects require a knowledge of MPs abundance, properties, fate and impact in the environment, which is essentially determined by two related features: the sources and the physico-chemical characteristics of MPs. Micropollutants including pharmaceuticals, antibiotics and hormones can enter the aquatic environment through both diffuse and point sources, but in urbanised regions wastewater treatment plants (WWTPs) play a crucial role in their dissemination. Conventional WWTPs are effective in removal of macropollutants (e.g. nutrients, suspended solids and some trace elements), while MPs may go through the treatment unchanged or be removed at different rates. Most of the EU countries are convinced that the presence of MPs in the environment poses a serious problem, particularly in highly populated regions where surface water resources serve as a source of potable water. Presently, various technical solutions are available and have been proven possible to integrate with existing treatment processes in an expedient manner. The solutions that have been evaluated are mainly based on ozonation and/or activated carbon treatment technologies which may definitely be considered the most effective compared to the costs incurred.

  • Implementation of Hermite-Ritz method and Navier’s Technique for Vibration of Functionally Graded Porous Nanobeam Embedded in Winkler-Pasternak Elastic Foundation Using bi-Helmholtz type of nonlocal elasticity
    • Subrat Kumar Jena
    • S. Chakraverty
    • Mohammad Malikan
    • Hamid M. Sedighi
    2020 Full text Journal of Mechanics of Materials and Structures

    Present study is devoted to investigating the vibration characteristics of Functionally Graded (FG) porous nanobeam embedded in an elastic substrate of Winkler-Pasternak type. Classical beam theory (CBT) or Euler-Bernoulli beam theory (EBT) has been incorporated to address the displacement of the FG nanobeam. Bi-Helmholtz type of nonlocal elasticity is being used to capture the small scale effect of the FG nanobeam. Further, the nanobeam is assumed to have porosity, distributed evenly along the thickness throughout the cross-section. Young’s modulus and mass density of the nanobeam are considered to vary along the thickness from ceramic to metal constituents in accordance with power-law exponent model. A numerically efficient method, namely the Hermite-Ritz method, is incorporated to compute the natural frequencies of Hinged-Hinged (HH), Clamped-Hinged (CH), and Clamped-Clamped (CC) boundary conditions. A closed-form solution is also obtained for Hinged-Hinged (HH) boundary condition by employing Navier’s technique. The advantages of using Hermite polynomials as shape functions are orthogonality, a large domain that makes the method more computationally efficient and avoids ill-conditioning for higher values of polynomials. Additionally, the present results are validated with other existing results in special cases demonstrating excellent agreement. A comprehensive study has been carried out to justify the effectiveness or convergence of the present model or method. Likewise, impacts of various scaling parameters such as Helmholtz and bi-Helmholtz types of nonlocal elasticity, porosity volume fraction index, power-law exponent, and elastic foundation on frequency parameters have been investigated.

  • Implementation of spatial/polarization diversity for improved-performance circularly polarized multiple-input-multiple-output ultra-wideband antenna
    • Ubaid Ullah
    • Ismail Mabrouk
    • Sławomir Kozieł
    • Muath Al-hasan
    2020 Full text IEEE Access

    In this paper, spatial and polarization diversities are simultaneously implemented in an ultra-wideband (UWB) multiple-input-multiple-output (MIMO) antenna to reduce the correlation between the parallel-placed radiators. The keystone of the antenna is systematically modified coplanar ground planes that enable excitation of circular polarization (CP). To realize one sense of circular polarization as well as ultra-wideband operation, an extended rectangular slot is etched on the left-hand-side of the coplanar waveguide (CPW) feed. This is combined with the asymmetrical ground plane geometry on the right-hand-side of the feeding line. The current flowing on the slotted ground plane forms a quasi-loop and generates CP, whereas the combination of the vertical current on the feedline and the horizontal current on the asymmetric ground plane adds to the axial ratio (AR) bandwidth. To implement the MIMO design with polarization and spatial diversity, the position of the coplanar ground planes is switched with respect to the feedline, and placed in a parallel formation with the edge-to-edge distance of 0.29λ0 . All geometrical parameters are optimized at the full-wave level of description before prototyping and experimental characterization. Simulation and measured results indicate that the proposed MIMO antenna features approximately 82% impedance bandwidth from 2.9 GHz to 7.1 GHz and 68.5% (3.1 GHz- 6.35 GHz) AR bandwidth. Moreover, the peak envelop correlation coefficient (ECC) is below 0.003, which corresponds to almost no correlation between the radiators. The antenna can be operated with either bidirectional or unidirectional characteristics, covering multiple commercial application bands including WLAN and WiMax.

  • Implementation Of The Innovative Radiolocalization System VCS-MLAT (Voice Communication System Multilateration)
    • Szymon Wiszniewski
    • Olga Błaszkiewicz
    • Alicja Olejniczak
    • Jarosław Sadowski
    • Jacek Stefański
    2020

    In the article the concept of the radiolocalization subsystem of the VHF communication for aviation VCS-MLAT (Voice Communication System – Multilateration) is presented. The distributed localization system can estimate the position of the aircraft using the audio signals from aircraft transmitters in the VHF band (118-136 MHz). This paper shows initial verification of the possibility to use voice airband communication to estimate the position of the aircraft. Main assumptions of the project and the structure of the localization modules (ground receiver stations) are also presented.

  • Improved degradation of etodolac in the presence of core-shell ZnFe2O4/SiO2/TiO2 magnetic photocatalyst
    • Eryka Mrotek
    • Szymon Dudziak
    • Izabela Malinowska
    • Daniel Pelczarski
    • Zuzanna Ryżyńska
    • Anna Zielińska-Jurek
    2020 Full text SCIENCE OF THE TOTAL ENVIRONMENT

    In the present study, susceptibility to photocatalytic degradation of etodolac, 1,8-diethyl-1,3,4,9 – tetrahydro pyran - [3,4-b] indole-1-acetic acid, which is a non-steroidal anti-inflammatory drug frequently detected in an aqueous environment, was for the first time investigated. The obtained p-type TiO2-based photocatalyst coupled with zinc ferrite nanoparticles in a core-shell structure improves the separation and recovery of nanosized TiO2 photocatalyst. The characterization of ZnFe2O4/SiO2/TiO2, including XRD, XPS, TEM, BET, DR/UV-Vis, impedance spectroscopy and photocatalytic analysis, showed that magnetic photocatalyst containing anatase phase revealed markedly improved etodolac decomposition and mineralization measured as TOC removal compared to photolysis reaction. The effect of irradiation and pH range on photocatalytic decomposition of etodolac was studied. The most efficient degradation of etodolac was observed under simulated solar light for a core-shell ZnFe2O4/SiO2/TiO2 magnetic photocatalyst at pH above 4 (pKa=4.7) and below 7. The irradiation of etodolac solution in a broader light range revealed a synergetic effect on its photodegradation performance. After only 20 min of degradation, about 100% of etodolac was degraded. Based on the photocatalytic analysis in the presence of scavengers and HPLC analysis, the transformation intermediates and possible photodegradation pathways of etodolac were studied. It was found that ∙O2- attack on C2-C3 bond inside pyrrole ring results mostly in the hydroxylation of the molecule, which next undergoes CH2COOH detachment to give 1,9-diethyl-3,4-dihydro-pyrano[3,4-b]indol-4a-ol. The obtained compound should further undergo subsequent hydropyran and pyrrole ring breaking to give a family of benzene derivatives.

  • Improved model of isothermal and incompressible fluid flow in pipelines versus the Darcy–Weisbach equation and the issue of friction factor
    • Zdzisław Kowalczuk
    • Marek Tatara
    2020 Full text JOURNAL OF FLUID MECHANICS

    In this article, we consider the modelling of stationary incompressible and isothermal one-dimensional fluid flow through a long pipeline. The approximation of the average pressure in the developed model by the arithmetic mean of inlet and outlet pressures leads to the known empirical Darcy–Weisbach equation. Most importantly, we also present another improved approach that is more accurate because the average pressure is estimated by integrating the pressure along the pipeline. Through appropriate transformation, we show the difference between the Darcy–Weisbach equation and the improved model that should be treated as a Darcy–Weisbach model error, in multiplicative and additive form. This error increases when the overall pressure drop increases. This symptomatic phenomenon is discussed in detail. In addition, we also consider four methods of estimating the coefficient of friction, assess the impact of pressure difference on the estimated average flow velocity and, based on experimental data, we show the usefulness of new proposals in various applications.

  • Improved-Efficacy Optimization of Compact Microwave Passives by Means of Frequency-Related Regularization
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    • Hasan Alhasan
    2020 Full text IEEE Access

    Electromagnetic (EM)-driven optimization is an important part of microwave design, especially for miniaturized components where the cross-coupling effects in tightly arranged layouts make traditional (e.g., equivalent network) representations grossly inaccurate. Efficient parameter tuning requires reasonably good initial designs, which are difficult to be rendered for newly developed structures or when re-design for different operating conditions or material parameters is required. If global search is needed, due to either the aforementioned issues or multi-modality of the objective function, the computational cost of the EM-driven design increases tremendously. This paper introduces a frequency-related regularization as a way of improving the efficacy of simulation-based design processes. Regularization is realized by enhancing the conventional (e.g., minimax) objective function using a dedicated penalty term that fosters the alignment of the circuit characteristics (e.g., the operating frequency or bandwidth) with the target values specified by the design requirement. This leads to smoothening of the objective function landscape, improves reliability of the optimization process, and reduces its computational cost as compared to the standard formulation. An added benefit is the increased immunity to poor initial designs and multi-modality issues. In particular, regularization can make local search routines sufficient in situations where global optimization would normally be necessary. The presented approach is validated using two miniaturized circuits, a rat-race and a branch line coupler. The numerical results demonstrate its superiority over conventional design problem formulations in terms of reliability of the optimization process.

  • Improvement of Performance Level of Steel Moment-Resisting Frames Using Tuned Mass Damper System
    • Masoud Dadkhah
    • Reza Kamgar
    • Heisam Heidarzadeh
    • Anna Jakubczyk-Gałczyńska
    • Robert Jankowski
    2020 Full text Applied Sciences-Basel

    In this paper, parameters of the tuned mass dampers are optimized to improve the performance level of steel structures during earthquakes. In this regard, a six-story steel frame is modeled using a concentrated plasticity method. Then, the optimum parameters of the Tuned Mass Damper (TMD) are determined by minimizing the maximum drift ratio of the stories. The performance level of the structure is also forced to be located in a safety zone. The incremental dynamic analysis is used to analyze the structural behavior under the influence of the artificial, near- and far-field earthquakes. The results of the investigation clearly show that the optimization of the TMD parameters, based on minimizing the drift ratio, reduces the structural displacement, and improves the seismic behavior of the structure based on Federal Emergency Management Agency (FEMA -356). Moreover, the values of base shear have been decreased for all studied records with peak ground acceleration smaller or equal to 0.5 g.

  • Improvement of ships seakeeping performance by application of the full-scale cfd simulations
    • Karol Niklas
    • Hanna Pruszko
    2020

    The ship’s fuel economy is increasingly important. The paper presents the effect of redesigning a case study ship for increasing seakeeping performance. Selected wave parameters reflect very difficult operational conditions existing on the North Sea and the Baltic Sea. The analyzed variants of a case study ship represent the latest developments of modern hull forms. The concepts similar to V-shaped bulbous bow, X-bow, X-aft, B-bow were adopted. Full-scale CFD simulations were performed to analyze the influence of innovative hull forms on the added resistance, heave and pitch motions for head waves and two vessel speeds. It was found that with the use of Full-scale CFD simulations it is possible to capture phenomena that cause ship’s non-linear behavior. The calculated relation between added resistance and ships’ vertical motions was opposite to linear strip theory. It proves that the results obtained by linear strip theory method and the CFD can differ significantly.

  • Improvement of subsoil and railway substructure by explosive means.
    • Eligiusz Mieloszyk
    • Anita Milewska
    • Mariusz Wyroślak
    2020

    Quick and effective method of subsoil and railway substructure improvement by using explosive means (registered trade name: microblasting) allowes design and construct railways on lowered bearing soils (i.e. wetlands, marshlands, industrial by-products, municipal wastes, degraded antropogenic embankments). It is usefull and recommendable technology to construct new railways, modernization or maintenance and repairing of old ones (often associated with modernization). Properly improved subsoil and railway substructure is a warranty of reliability for railways. It increase vitality and security of rail traffic.

  • Improving Objective Speech Quality Indicators in Noise Conditions
    • Krzysztof Kąkol
    • Grazina Korvel
    • Bożena Kostek
    2020

    This work aims at modifying speech signal samples and test them with objective speech quality indicators after mixing the original signals with noise or with an interfering signal. Modifications that are applied to the signal are related to the Lombard speech characteristics, i.e., pitch shifting, utterance duration changes, vocal tract scaling, manipulation of formants. A set of words and sentences in Polish, recorded in silence, as well as in the presence of interfering signals, i.e., pink noise and the so-called babble speech, also referred to as the “cocktail-party” effect is utilized. Speech samples were then processed and measured utilizing objective indicators to check whether modifications applied to the signal in the presence of noise increased values of the speech quality index, i.e., PESQ (Perceptual Evaluation of Speech Quality) standard.

  • Improving the Accuracy of Automatic Reconstruction of 3D Complex Buildings Models from Airborne Lidar Point Clouds
    • Marek Kulawiak
    • Zbigniew Łubniewski
    2020 Full text Remote Sensing

    Due to high requirements of variety of 3D spatial data applications with respect to data amount and quality, automatized, effcient and reliable data acquisition and preprocessing methods are needed. The use of photogrammetry techniques—as well as the light detection and ranging (LiDAR) automatic scanners—are among attractive solutions. However, measurement data are in the form of unorganized point clouds, usually requiring transformation to higher order 3D models based on polygons or polyhedral surfaces, which is not a trivial process. The study presents a newly developed algorithm for correcting 3D point cloud data from airborne LiDAR surveys of regular 3D buildings. The proposed approach assumes the application of a sequence of operations resulting in 3D rasterization, i.e., creation and processing of a 3D regular grid representation of an object, prior to applying a regular Poisson surface reconstruction method. In order to verify the accuracy and quality of reconstructed objects for quantitative comparison with the obtained 3D models, high-quality ground truth models were used in the form of the meshes constructed from photogrammetric measurements and manually made using buildings architectural plans. The presented results show that applying the proposed algorithm positively influences the quality of the results and can be used in combination with existing surface reconstruction methods in order to generate more detailed 3D models from LiDAR scanning.

  • Improving the Performance of a Graphite Foil/Polyaniline Electrode Material by a Thin PEDOT:PSS Layer for Application in Flexible, High Power Supercapacitors
    • Zuzanna Zarach
    • Konrad Trzciński
    • Marcin Łapiński
    • Anna Lisowska-Oleksiak
    • Mariusz Szkoda
    2020 Full text Materials

    In this study, we present a novel strategy for enhancing polyaniline stability and thus obtaining an electrode material with practical application in supercapacitors. A promising (graphite foil/polyaniline/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) GF/PANI/PEDOT:PSS) electrode material was characterized and used in the construction of a symmetric supercapacitor that provides an outstanding high power density. For this purpose, the electropolymerization of PANI was carried out on a graphite foil and then a thin protective layer of PEDOT:PSS was deposited. The presence of the nanometer PEDOT:PSS layer made it possible to widen the electroactivity potential range of the electrode material. Moreover, the synergy between materials positively affected the amount of accumulated charge, and thus the thin PEDOT:PSS layer contributed to enhancing the specific capacity of the electrode material. The electrochemical performance of the GF/PANI/PEDOT:PSS electrode, as well as the symmetrical supercapacitor, was investigated by cyclic voltammetry and galvanostatic charge/discharge cycles in 1 M H2SO4 at room temperature. The fabricated electrode material shows a high specific capacitance (Csp) of 557.4 Fg−1 and areal capacitance (Careal) of 2600 mF·cm−2 in 1 M H2SO4 at a current density of 200 mA·cm−2 (~4 A·g−1). The supercapacitor performance was studied and the results show that a thin PEDOT:PSS layer enables cycling stability improvement of the device from 54% to 67% after 10,000 cycles, and provides a high specific capacity (159.8 F·g−1) and a maximum specific power (18,043 W·kg−1) for practical applications.

  • Improving the Performance of Ontological Querying by using a Contextual Approach
    • Wojciech Waloszek
    • Aleksander Waloszek
    2020 Full text Procedia Computer Science

    In the paper we present the results of experiment we performed to determine whether a contextual approach may be used to increase the performance of querying a knowledge base. For the experiments we have used a unique setting where we put much effort in developing a contextual and a non-contextual ontology which are as much close counterparts as possible. To achieve this we created a contextual version of a non-contextual ontology and reformulated the set of competency questions to reflect the contextual structure of the newly created knowledge base. The results of the experiment strongly suggest that using contexts might be advantageous for improving performance, and also show the further ways of development of the approach.

  • Improving the procedure of probabilistic load testing design of typical bridges based on structural response similarities
    • Piotr Owerko
    • Karol Winkelmann
    2020 Full text Archives of Civil Engineering

    This paper concerns load testing of typical bridge structures performed prior to operation. In-situ tests of a two-span post-tensioned bridge loaded with three vehicles of 38-ton mass each formed the input of this study. On the basis of the results of these measurements, an advanced FEM model of the structure was developed for which the sensitivity analysis was performed for chosen uncertainty sources. Three uncorrelated random variables representing material uncertainties, imperfections of positioning, and total mass of loading vehicles were indicated. Afterward, two alternative FE models were created based on a fully parametrized geometry of the bridge, differing by a chosen global parameter – the skew angle of the structure. All three solid models were subjected to probabilistic analyses with the use of the second-order Response Surface Method in order to define the features of the structural response of the models. It was observed that both the ranges of expected deflections and their corresponding mean values decreased with an increase in the skewness of the bridge models. Meanwhile, the coefficient of variation and the relative difference between the mean value and boundary quantiles of the ranges remain insensitive to the changes in the skew angle. Owing to this, a procedure was formulated to simplify the process of load testing design of typical bridges differing by a chosen global parameter. The procedure allows - if certain conditions are fulfilled - to perform probabilistic calculations only once and use the indicated probabilistic parameters in the design of other bridges for which calculations can be performed deterministically.

  • Improving the Quality of Magnetic Signature Reproduction by Increasing Flexibility of Multi-Dipole Model Structure and Enriching Measurement Information
    • Jarosław Tarnawski
    • Adam Cichocki
    • Tomasz Rutkowski
    • Krystian Buszman
    • Mirosław Wołoszyn
    2020 Full text IEEE Access

    The paper presents the construction of a multi-dipole model that allows reproducing magneticsignatures of ferromagnetic objects. The virtual object used in the paper is an ellipsoid, which is the sourceof synthetic data. To make the situation more realistic, noise is added to the synthetic data. Two significantimprovements compared to previous work are presented. Three-axial magnetometers are introduced insteadof uniaxial magnetometers. However, a more important change is the modification of the model structurethat allows placing dipoles on the entire plane, e.g. object’s deck. The multi-dipole model consists of ana priori assumed number of permanent and induced single-dipole models. Each single dipole is described bythree magnetic moments and, depending on the applied approach, one or two dipole position parameters. Thenon-linear least-squares optimization method is used to determine model parameters. To assess the qualityof magnetic signature reproduction, qualitative and quantitative forms are used. The final quality assessmentis based on differences between the reference fields and the fields determined from the multi-dipole model.The applied modifications bring significant improvement, however, only their combined application allowsto restore magnetic signatures with good quality for directions other than for which the data were available.

  • Improving the Survivability of Carrier Networks to Large-Scale Disasters
    • Amaro de Sousa
    • Jacek Rak
    • Fábio Barbosa
    • Dorabella Santos
    • Deepak Mehta
    2020

    This chapter is dedicated to the description of methods aiming to improve the survivability of carrier networks to large-scale disasters. First, a disaster classification and associated risk analysis is described, and the disaster-aware submarine fibre-optic cable deployment is addressed aiming to minimize the expected costs in case of natural disasters. Then, the chapter addresses the improvement of the network connectivity resilience to multiple node failures caused by malicious human activities. Two improvement methods are described aiming to minimize the connectivity impact of any set of node failures. One method is based on the appropriate selection of a set of network nodes to be made robust to node attacks. The other is a topology design method aiming to select the most appropriate set of links, within a given fibre budget, that provide the best resilience to multiple node failures. The latter method can also be applied to the upgrade task of a current network topology.

  • Imunofan—RDKVYR Peptide—Stimulates Skin Cell Proliferation and Promotes Tissue Repair
    • Justyna Sawicka
    • Maria Dzierżyńska
    • Anna Wardowska
    • Milena Deptuła
    • Piotr Rogujski
    • Paweł Sosnowski
    • Natalia Filipowicz
    • Alina Mieczkowska
    • Piotr Sass
    • Anna Pawlik
    • Aleksandra Hać
    • Adriana Schumacher
    • Magdalena Gucwa
    • Natalia Karska
    • Jolanta Kamińska
    • Rafał Płatek
    • Jarosław Mazuryk
    • Jacek Zieliński
    • Karolina Kondej
    • Piotr Młynarz
    • Piotr Mucha
    • Piotr Skowron
    • Łukasz Janus
    • Anna Herman-Antosiewicz
    • Paweł Sachadyn
    • Artur Czupryn
    • Arkadiusz Piotrowski
    • Michał Pikuła
    • Sylwia Rodziewicz-Motowidło
    2020 Full text MOLECULES

    Regeneration and wound healing are vital to tissue homeostasis and organism survival. One of the biggest challenges of today’s science and medicine is finding methods and factors to stimulate these processes in the human body. Effective solutions to promote regenerative responses will accelerate advances in tissue engineering, regenerative medicine, transplantology, and a number of other clinical specialties. In this study, we assessed the potential efficacy of a synthetic hexapeptide, RDKVYR, for the stimulation of tissue repair and wound healing. The hexapeptide is marketed under the name “Imunofan” (IM) as an immunostimulant. IM displayed stability in aqueous solutions, while in plasma it was rapidly bound by albumins. Structural analyses demonstrated the conformational flexibility of the peptide. Tests in human fibroblast and keratinocyte cell lines showed that IM exerted a statistically significant (p < 0.05) pro-proliferative activity (30–40% and 20–50% increase in proliferation of fibroblast and keratinocytes, respectively), revealed no cytotoxicity over a vast range of concentrations (p < 0.05), and had no allergic properties. IM was found to induce significant transcriptional responses, such as enhanced activity of genes involved in active DNA demethylation (p < 0.05) in fibroblasts and activation of genes involved in immune responses, migration, and chemotaxis in adipose-derived stem cells derived from surgery donors. Experiments in a model of ear pinna injury in mice indicated that IM moderately promoted tissue repair (8% in BALB/c and 36% in C57BL/6 in comparison to control).

  • In silico design of telomerase inhibitors.
    • Maciej Bagiński
    • Katarzyna Serbakowska
    2020 Full text DRUG DISCOVERY TODAY

    Telomerase is a reverse transcriptase enzyme involved in DNA synthesis at the end of linear chromosomes. Unlike in most other cells, telomerase is reactivated most cancerous cells and, therefore, has become a promising new anticancer target. Despite extensive research, direct telomerase inhibitors have yet not been introduced to the clinics because of the complexity of this enzyme. Structures of this protein from simple organisms and human homology models are currently available and have been used in structure-based drug design efforts to find potential inhibitors. Different is silico strategies have been applied and different chemical groups have been explored. Here, we provide an overview of recent discoveries.

  • In Vitro Biological Characterization of Silver-Doped Anodic Oxide Coating on Titanium
    • Oleksandr Oleshko
    • Iryna Liubchak
    • Yevheniia Husak
    • Viktoriia Korniienko
    • Aziza Yusupova
    • Tetiana Oleshko
    • Rafal Banasiuk
    • Marek Szkodo
    • Igor-Matros Taranets
    • Alicja Kazek-Kęsik
    • Wojciech Simka
    • Maksym Pogorielov
    2020 Full text Materials

    Despite the high biocompatibility and clinical effectiveness of Ti-based implants, surface functionalization (with complex osteointegrative/antibacterial strategies) is still required. To enhance the dental implant surface and to provide additional osteoinductive and antibacterial properties, plasma electrolytic oxidation of a pure Ti was performed using a nitrilotriacetic acid (NTA)-based Ag nanoparticles (AgNP)-loaded calcium–phosphate solution. Chemical and structural properties of the surface-modified titanium were assessed using scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) and contact angle measurement. A bacterial adhesion test and cell culture biocompatibility with collagen production were performed to evaluate biological effectiveness of the Ti after the plasma electrolytic process. The NTA-based calcium– phosphate solution with Ag nanoparticles (AgNPs) can provide formation of a thick, porous plasma electrolytic oxidation (PEO) layer enriched in silver oxide. Voltage elevation leads to increased porosity and a hydrophilic nature of the newly formed ceramic coating. The silver-enriched PEO layer exhibits an effective antibacterial effect with high biocompatibility and increased collagen production that could be an effective complex strategy for dental and orthopedic implant development.

  • In Vitro Studies on Nanoporous, Nanotubular and Nanosponge-Like Titania Coatings, with the Use of Adipose-Derived Stem Cells
    • Michalina Ehlert
    • Aleksandra Radtke
    • Tomasz Jędrzejewski
    • Katarzyna Roszek
    • Michał Bartmański
    • Piotr Piszczek
    2020 Full text Materials

    In vitro biological research on a group of amorphous titania coatings of different nanoarchitectures (nanoporous, nanotubular, and nanosponge-like) produced on the surface of Ti6Al4V alloy samples have been carried out, aimed at assessing their ability to interact with adipose-derived mesenchymal stem cells (ADSCs) and affect their activity. The attention has been drawn to the influence of surface coating architecture and its physicochemical properties on the ADSCs proliferation. Moreover, in vitro co-cultures: (1) fibroblasts cell line L929/ADSCs and (2) osteoblasts cell line MG-63/ADSCs on nanoporous, nanotubular and nanosponge-like TiO2 coatings have been studied. This allowed for evaluating the impact of the surface properties, especially roughness and wettability, on the creation of the beneficial microenvironment for co-cultures and/or enhancing differentiation potential of stem cells. Obtained results showed that the nanoporous surface is favorable for ADSCs, has great biointegrative properties, and supports the growth of co-cultures with MG-63 osteoblasts and L929 fibroblasts. Additionally, the number of osteoblasts seeded and cultured with ADSCs on TNT5 surface raised after 72-h culture almost twice when compared with the unmodified scaffold and by 30% when compared with MG-63 cells growing alone. The alkaline phosphatase activity of MG-63 osteoblasts co-cultured with ADSCs increased, that indirectly confirmed our assumptions that TNT-modified scaffolds create the osteogenic niche and enhance osteogenic potential of ADSCs.

  • In vivo performance of intraperitoneal onlay mesh after ventral hernia repair
    • Izabela Lubowiecka
    • Agnieszka Tomaszewska
    • Katarzyna Szepietowska
    • Czesław Szymczak
    • Maciej Śmietański
    2020 Full text CLINICAL BIOMECHANICS

    Background: Ventral hernia repair needs to be improved since recurrence, postoperative pain and other complications are still reported in many patients. The behavior of implants in vivo is not sufficiently understood to design a surgical mesh mechanically compatible with the human abdominal wall. Methods: This analysis was based on radiological pictures of patients who underwent laparoscopic ventral hernia repair. The pictures show the trunk of the patient at rest in a standing position and under side bending. The change in the distance between different tacks due to trunk movement was analyzed, which allowed us to determine the in vivo elongation of the mesh incorporated into the abdominal wall. Findings: The relative elongations of the surgical mesh varied from a few percent to greater than 100% in two cases. The median of the median relative elongations obtained for all patients is 9.5%, and the median of the maximum relative elongations for all patients is 32.6%. The maximum elongation occurs between tacks that are next to each other. Trunk movement causes implant deformation, and this study provides quantitative information regarding changes in the distance between fasteners. Interpretation: The physiological movement of the human abdomen must be regarded as a very important factor in mesh deformation and should be considered in surgical practice to reduce the hernia recurrence rate and postoperative pain.

  • In vivoevaluation of the CB1allosteric modulator LDK1258 reveals CB1-receptor independent behavioral effects
    • Teresa Olszewska
    • Mustafa Mohammed
    • Giulia Donvito
    • Lauren Moncayo
    • Amelia Swafford
    • Justin Poklis
    • Ralph Grauer
    • Bogna Ignatowska-Jankowska
    • Debra A. Kendall
    • Dai Lu
    • Aron H. Lichtman
    2020 PHARMACOLOGY BIOCHEMISTRY AND BEHAVIOR

    In the present study, we examined whether LDK1258, which produces strong CB1receptor allosteric effects ininvitroassays, would elicitin vivoeffects consistent with allosteric activity. In initial studies, LDK1258 reducedfood consumption and elicited delayed antinociceptive effects in the chronic constrictive injury of the sciaticnerve (CCI) model of neuropathic pain, which unexpectedly emerged 4 h post-injection. UPLC-MS/MS analysisquantified significant levels of LDK1258 in both blood and brain tissue at 30 min post-administration thatremained stable up to 4 h. The observation that LDK1258 also produced respective antinociceptive and anorecticeffects in rimonabant-treated wild type mice and CB1(−/−) mice suggests an off-target mechanism of action.Likewise, LDK1258 produced a partial array of common cannabimimetic effects in the tetrad assay, which werenot CB1receptor mediated. Additionally, LDK1258 did not substitute for the CB1receptor orthosteric agonistsCP55,940 or anandamide in the drug discrimination paradigm. In otherinvivoassays sensitive to CB1receptorallosteric modulators, LDK1258 failed to shift the dose-response curves of either CP55,940 or anandamide inproducing thermal antinociception, catalepsy, or hypothermia, and did not alter the generalization curve ofeither drug in the drug discrimination assay. Thus, this battery of tests yielded results demonstrating thatLDK1258 produces antinociceptive effects in the CCI model of neuropathic pain, anorectic effects, and otherinvivopharmacological effects in a manner inconsistent with CB1receptor allosterism. More generally, this studyoffers a straightforward screening assay to determine whether newly synthesized CB1receptor allosteric mod-ulators translate to the whole animal.

  • Including the Dark Side of Entrepreneurship in the Entrepreneurship Education
    • Paweł Ziemiański
    • Jakub Golik
    2020 Full text Education Sciences

    Pursuing an entrepreneurial career is often rewarding in terms of both economic and psychological outcomes. However, becoming an entrepreneur also has its darker side that affects professional and personal life. Meanwhile, the positivity bias is prevalent in entrepreneurial education and research. It is recognized as emphasizing the advantages of becoming an entrepreneur and giving considerably less attention to potential downsides. Based on the theoretical model of met expectations, it is proposed that building an accurate and balanced image of the entrepreneurial career is crucial to help students prepare to pursue it successfully. Using data from SEAS (Survey on Entrepreneurial Attitudes of Students) Project, authors quantitatively test the perception of the severity of negative aspects of entrepreneurship among 513 business students from northern Poland. Further, the results of 16 semi-structured qualitative interviews conducted with mature and experienced entrepreneurs from the same region are presented. They are focused on the entrepreneurs’ perspective on the experienced dark sides and reveal employed coping strategies. A call is made to include these findings in designing university entrepreneurship programs by eliciting the awareness of the existence of the dark sides and indicating the means of their attenuation.

  • Incomplete Cross-Bonding in the MV Line. Experience from the Operation of MV Single Cable Lines
    • Krzysztof Dobrzyński
    • Zbigniew Lubośny
    • Jacek Klucznik
    • Janusz Grala
    • Dominik Falkowski
    2020 Full text ENERGIES

    Cable lines are one of the basic components of power systems. Medium and high voltage cables mainly comprise a metallic sheath, which is concentric to the main core conductor. There are several operating schemes of such cable lines, which differ in the place of earthing of sheaths and the possible use of the sheaths and/or conductors crossing. The sheaths cross-bonding is typically done in two places of one cable line section, and it allows to reduce power losses. Nevertheless, the use of incomplete sheaths crossing—only in one place on cable route may have economic justification. The paper presents an incomplete sheaths cross-bonding analysis of an existing medium voltage cable line. The results obtained by the mathematical model are validated by measurements taken on 30 October 2019 on an existing cable line. Measurements recorded on a real object for various systems of crossing sheaths are presented. The influence of incorrect sheaths crossing on the measured quantities was shown. In addition, the risk of excess voltage on the sheaths during short-circuits has been verified using a mathematical model.

  • Increasing the Geometrical and Interpretation Quality of Unmanned Aerial Vehicle Photogrammetry Products Using Super-Resolution Algorithms
    • Paweł Burdziakowski
    2020 Full text Remote Sensing

    Unmanned aerial vehicles (UAVs) have now become very popular in photogrammetric and remote-sensing applications. Every day, these vehicles are used in new applications, new terrains, and new tasks, facing new problems. One of these problems is connected with flight altitude and the determined ground sample distance in a specific area, especially within cities and industrial and construction areas. The problem is that a safe flight altitude and camera parameters do not meet the required or demanded ground sampling distance or the geometrical and texture quality. In the cases where the flight level cannot be reduced and there is no technical ability to change the UAV camera or lens, the author proposes the use of a super-resolution algorithm for enhancing images acquired by UAVs and, consequently, increase the geometrical and interpretation quality of the final photogrammetric product. The main study objective was to utilize super-resolution (SR) algorithms to improve the geometric and interpretative quality of the final photogrammetric product, assess its impact on the accuracy of the photogrammetric processing and on the traditional digital photogrammetry workflow. The research concept assumes a comparative analysis of photogrammetric products obtained on the basis of data collected from small, commercial UAVs and products obtained from the same data but additionally processed by the super-resolution algorithm. As the study concludes, the photogrammetric products that are created as a result of the algorithms' operation on high-altitude images show a comparable quality to the reference products from low altitudes and, in some cases, even improve their quality.

  • Increasing the lifetime of engineering structures through the use of composite laggings
    • Eligiusz Mieloszyk
    • Anita Milewska
    • Marcin Abramski
    2020

    The use of composite laggings prevents concrete (chemical and biological) corrosion. Columns coated with composite or reinforced composite are more resistant to negative environmental impact on concrete or steel. The mechanical properties of the reinforced casing also cause that these types of columns are more resistant to lateral forces. The applied casing limits carbonization of concrete and cyclical freezing and thawing with penetrating water, and thus increases the lifespan of columns exposed to water. Laboratory tests were carried out regarding the short-time load-carrying capacity of columns in a composite laggings.

  • Industry 4.0 Implementation Challenges in Manufacturing Industries: an Interpretive Structural Modelling Approach
    • Ahmad Reshad Bakhtari
    • Vineet Kumar
    • Mohammad Waris
    • Cesar Sanin
    • Edward Szczerbicki
    2020 Full text Procedia Computer Science

    For the last few years, the fourth industrial revolution, known as Industry 4.0, has been a hot topic among academics. Industry 4.0 literature involves researches presenting studies related to its different aspects including challenges, opportunities, implementation and adoption. However, a detailed study of challenges and barriers towards the Industry 4.0 implementation in manufacturing industries is missing. Hence, this paper aims to study and analyze the Industry 4.0 implementation challenges in manufacturing industries based on the expert opinions and the Interpretive Structural Modelling (ISM). The ISM analysis investigates the challenges in a structural base, finds the relationships between these challenges and finally shows how challenges affect each other to uncover the root cause triggering the other challenges. The industrial practitioners and managers can then take advantage of this analysis to know which challenge acts as the main barrier towards Industry 4.0 implementation and to be focused first in order to reach a solution.

  • Indywidualne programy integracyjne dla uchodźców i cudzoziemców objętych ochroną uzupełniającą z państw poradzieckich w dobie przynależności Polski do Unii Europejskiej
    • Krystyna Gomółka
    2020

    Celem pracy jest analiza uwarunkowań i skali obejmowania indywidualnymi programami integracyjnymi obywateli państw poradzieckich, którym przyznawano status uchodźcy i ochronę uzupełniającą w Polsce w okresie od 2004 r. do 2018 r., tj. od przystąpienia przez Polskę do Unii Europejskiej. Omawiane są następujące zagadnienia: uwarunkowania formalno-prawne ochrony międzynarodowej w Polsce, zasady przyznawania indywidualnych programów integracyjnych, skala udziału obywateli państw poradzieckich objętych ochroną międzynarodową w programach integracyjnych na tle innych grup cudzoziemców. Zaprezentowano także ocenę skuteczności programów integracyjnych oferowanych uchodźcom w Polsce opartą na badaniach przeprowadzonych przez Beatę Samoraj i Mieczysława Bienieckiego. Z kolei ustalenia dokonane przez Sławomira Łodzińskiego i Jana Kruszyńskiego pozwoliły ujawnić oceny, jakie Polacy formułują pod adresem tych programów oraz pomocy przyznawanej cudzoziemcom.

  • Influence of addition of carbon nanotubes on rheological properties of selected liquid lubricants - a computer simulation study
    • Anjali Chopra
    • Szymon Winczewski
    2020 Full text TASK Quarterly

    This work is motivated by the improvement of anti-friction properties of lubricants by addition of CNTs proved experimentally in literature. In particular, a methodology is developed to compute the shear viscosity of liquid lubricants (Propylene Glycol) based on Molecular Dynamics simulation. Non-Equilibrium molecular dynamics (NEMD) approach is used with a reactive force field ReaxFF implemented in LAMMPS. The simulations are performed using the canonical (NVT) ensemble with the so-called SLLOD algorithm. Couette flow is imposed on the system by using Lees-Edwards periodic boundary conditions. Suitable parameters such as simulation time and imposed shear velocity are obtained. Using these parameters, the influence of addition of 27 wt% CNTs to Propylene Glycol on its viscosity is analyzed. Results show that 3.2 million time-steps with a 0.1 fs time-step size is not sufficient for the system to reach equilibrium state for such calculations. With the available computational resources, a shear velocity of 5 × 10−5Å/fs was observed to give viscosity value with approximately 43% error as compared to the experimental value. Moreover, the lubricant exhibited a shear thinning behaviour with increasing shear rates. CNTs enhanced the lubricant’s viscosity by 100-190% depending upon the averaging method used for calculation.

  • Influence of alkaline and oxidative pre-treatment of waste corn cobs on biohydrogen generation efficiency via dark fermentation
    • Karolina Kucharska
    • Piotr Rybarczyk
    • Iwona Hołowacz
    • Donata Konopacka-Łyskawa
    • Edyta Słupek
    • Patrycja Makoś-Chełstowska
    • Hubert Cieśliński
    • Marian Kamiński
    2020 BIOMASS & BIOENERGY

    Stages of waste corn cobs processing leading to the production of biohydrogen via dark fermentation are presented and discussed in this paper. Firstly, the effects of pretreatment conditions i.e. alkaline, alkaline-oxidizing and Fenton oxidizing pre-treatment of lignocellulosic biomass on the removal of lignin were examined. The solid residue obtained in the first stage was subjected to saccharification by means of enzymatic hydrolysis. The composition of enzymatic hydrolysates and fermentation broths were investigated in order to determine the content of sugars as well as phenolic compounds and fermentation broth composition containing organic acids. The dark fermentation process of the obtained hydrolysates was carried using mixed wastewater sludge from the municipal sewage treatment plant. The highest hydrogen production was obtained for alkaline pre-treated hydrolysates. The effects of investigated chemical pre-treatment methods were discussed in terms of the obtained saccharification efficiency and composition of the gas phase formed during the fermentation, and the composition of fermentation broth.

  • INFLUENCE OF CERAMIC COATING ON MECHANICAL PROPERTIES OF STAINLESS STEEL
    • Dionizy Czekaj
    • Agata Lisińska-Czekaj
    • Krzysztof Krzysztofowicz
    2020 Full text ARCHIVES OF METALLURGY AND MATERIALS

    Crystal structure and phase composition of stainless steel substrates (AISI 304 type) was studied and it was found that they adopted the cubic symmetry. The calculated elementary cell parameter for the mayor Fe-Ni phase (weight fraction 99%) was a = 3.593 Å, whereas the mean grain size was <D> = 2932 Å. Morphology of the stainless steel substrate surface was studied with profilometry. Mechanical properties of the stainless steel substrates and stainless steel substrates coated with ceramic layer of barium strontium titanate were studied with microhardness tester. For measurements performed according to the Vickers method the average microhardness was found HV = 189 or HV = 186 for the “in-line” and “mapping” measurement pattern, respectively. The sol-gel method was used to coat the surface of the stainless steel substrate with a thin ceramic layer of the chemical composition Ba0.6Sr0.4TiO3. It was found that the stainless steel substrate covered with sol-gel deposited ceramic coating exhibited the average hardness within the range HV = 217 up to HV = 235 for loading force F = 98 mN and F = 0.98 N, respectively. The Knopp method was also used and it was found that the stainless steel substrate with Ba0.6Sr0.4TiO3 coating exhibited hardness HK = 386.

  • Influence of chemical structure on physicochemical properties and thermal decomposition of the fully bio-based poly(propylene succinate-co-butylene succinate)s
    • Paulina Parcheta
    • Janusz Datta
    2020 Full text POLYMER TESTING

    In this work, two polyesters and four copolyesters were studied. All materials were synthesized to obtain the monomers dedicated for thermoplastic polyurethane elastomers. For this type of PUR, the monomers should characterize by appropriate selected physicochemical properties and macromolecular structure distribution, which depends on synthesis conditions. The study of chemical structure with extensive and knowledgeable analysis of formed macromolecules of synthesized bio-based copolyesters was conducted with the use of FTIR and 1H NMR spectroscopy and MALDI-ToF mass spectrometry. The results allowed to propose the majority of probable chemical structures of macromolecules formed during synthesis. Moreover, the impact of the structure on the thermal stability of the obtained copolyesters was also determined with the use of thermogravimetric analysis. The temperature of the beginning of thermal decomposition equaled even 330oC. Furthermore, the results of DSC-TG/QMS coupled method confirmed that all prepared polyesters degraded by α and β-hydrogen bond scission mechanisms.

  • Influence of Dielectric Overlay Dimensions on Performance of Miniaturized ESPAR Antenna
    • Mateusz Czeleń
    • Mateusz Rzymowski
    • Krzysztof Nyka
    • Łukasz Kulas
    2020 Full text

    In this paper, the influence of dielectric overlay size on miniaturized ESPAR antenna performance has been investigated. The dielectric overlay’s main function is antenna’s size reduction but it can also be used to modify its radiation pattern. This creates the possibility of easy adopting antenna parameters to different applications by swapping used overlay. In particular, the lowering of antenna’s main beam elevation direction has been considered. By using selected alternative overlay one can obtain a 20° lower beam. The design was confirmed by realization and measurements.

  • Influence of Dielectric Overlay Permittivity on Size and Performance of Miniaturized ESPAR Antenna
    • Mateusz Czeleń
    • Mateusz Rzymowski
    • Krzysztof Nyka
    • Łukasz Kulas
    2020 Full text

    In this paper, influence of dielectric overlay permittivity on miniaturized ESPAR antenna parameters is presented. ESPAR antenna is a low-cost and energy-efficient way to implement beam steering capability to a node and improve network performance. The antenna size reduction is obtained by embedding its active and passive elements in ABS based materials of relative permittivity equal to 4, 5.5 and 7.5 in order to achieve network node compact size. Simulation results of three optimized for particular dielectric constant designs are presented and tradeoff between dimensions reduction and performance is discussed. Selected materials and antenna design are dedicated to be fabricated in 3D print technology, so can be easily prototyped.

  • Influence of process of straightening ship hull structure made of 316L stainless steel on corrosion resistance and mechanical properties
    • Jakub Kowalski
    • Łukasz Licznerski
    • Milena Supernak-Marczewska
    • Krzysztof Emilianowicz
    2020 Full text Polish Maritime Research

    The AISI 316L type steel belongs to the group of chromium-nickel stainless steels. They are determined according to European standards as X2CrNiMo17-12-2 and belong to the group of austenitic stainless steels. Steels of this group are used for elements working in seawater environments, for installations in the chemical, paper, and food, industries, for architectural elements, and many others. The chemical composition of corrosion-resistant austenitic steels provides them with an austenite structure that is stable in a wide temperature range, under appropriate conditions for heating, soaking, and cooling. 316L steel plate was subjected to a technological treatment of hot straightening with an oxyacetylene torch, which is not commonly used for this type of steel, mainly due to the lack of objective assessment of whether the austenitizing temperature has been achieved and the stability of the heat treatment process is ensured. The single-phase structure of austenite with high corrosion resistance, without precipitation of carbides, steel is obtained by supersaturation in water from 1100°C. The purpose of the presented research was to determine the usefulness of the flame straightening process for a ship structure made of 316L steel.

  • Influence of Selected Warm Mix Asphalt Additives on Cracking Susceptibility of Asphalt Mixtures
    • Marcin Stienss
    • Cezary Szydłowski
    2020 Full text Materials

    Warm mix asphalt (WMA) has been widely accepted as a future asphalt paving technology. Besides clear advantages, there are still some concerns regarding durability and long-term performance of pavements made with this type of asphalt mixtures. One of the most important issues is low temperature behaviour of WMA because certain additives used for temperature reduction can aect bitumen properties. This paper presents the evaluation of low-temperature properties of laboratory-produced asphalt concrete for wearing course with selected WMA additives. One type of bitumen with paving grade 50/70 and fiveWMAadditives of dierent nature (organic, surface tension reducer and combination of both) were used in this study. The production and compaction temperature of mixtures containing WMA additives was 25 C lower in comparison with the temperature of the reference mix. To assess the susceptibility of WMA to low-temperature cracking, Semi-Circular Bending (SCB) and Thermal Stress Restrained Specimen Test (TSRST) were used. Supplementary rating was made by analysing Bending Beam Rheometer (BBR) test results of asphalt binders.

  • Influence of several biodegradable components added to pure and nanosilver-doped PMMA bone cements on its biological and mechanical properties
    • Marcin Wekwejt
    • Marta Michalska-Sionkowska
    • Michał Bartmański
    • Małgorzata Nadolska
    • Krzysztof Łukowicz
    • Anna Pałubicka
    • Anna Maria Osyczka
    • Andrzej Zieliński
    2020 Full text Materials Science & Engineering C-Materials for Biological Applications

    Acrylic bone cements (BC) are wildly used in medicine. Despite favorable mechanical properties, processability and inject capability, BC lack bioactivity. To overcome this, we investigated the effects of selected biodegradable additives to create a partially-degradable BC and also we evaluated its combination with nanosilver (AgNp). We hypothesized that using above strategies it would be possible to obtain bioactive BC. The Cemex was used as the base material, modified at 2.5, 5 or 10 wt% with either cellulose, chitosan, magnesium, polydioxanone or tricalcium-phosphate. The resulted modified BC was examined for surface morphology, wettability, porosity, mechanical and nanomechanical properties and cytocompatibility. The composite BC doped with AgNp was also examined for its release and antibacterial properties. The results showed that it is possible to create modified cement and all studied modifiers increased its porosity. Applying the additives slightly decreased BC wettability and mechanical properties, but the positive effect of the additives was observed in nanomechanical research. The relatively poor cytocompatibility of modified BC was attributed to the unreacted monomer release, except for polydioxanone modification which increased cells viability. Furthermore, all additives facilitated AgNp release and increased BC antibacterial effectiveness.Our present studies suggest the optimal content of biodegradable component for BC is 5 wt%. At this content, an improvement in BC porosity is achieved without significant deterioration of BC physical and mechanical properties. Polydioxanone and cellulose seem to be the most promising additives that improve porosity and antibacterial properties of antibiotic or nanosilver-loaded BC. Partially-degradable BC may be a good strategy to improve their antibacterial effectiveness, but some caution is still required regarding their cytocompatibility.

  • INFLUENCE OF TACK WELDS DISTRIBUTION AND WELDING SEQUENCE ON THE ANGULAR DISTORTION OF TIG WELDED JOINT
    • Jacek Tomków
    • Konrad Sobota
    • Sławomir Krajewsk
    2020 Full text Facta Universitatis-Series Mechanical Engineering

    In this paper the influence of tack welds distribution and welding sequence on angular distortion of the Tungsten Inert Gas (TIG) welded joint was tested. Additionally, the effect of welding current on angular distortion was assessed. For research X2CrTiNb18 (AISI 441) stainless steel (2.5 mm thick) was chosen. During research specimens were prepared with different distributionsof tack welds. Then they were welded by different welding sequenceswith the use of different welding current values. After welding the angular distortion of each specimen was measured by using thecoordinate measuring machine. In the next step specimens were cut. Cross-sections were polished and the metallographic macroscopic testing was conducted to check the geometry of performed welds. Performed experiments allowed determining the optimal tack weld sequence and welding parameters for welding thin stainless steel sheets.

  • Influence of Two-Stage Anodization on Properties of the Oxide Coatings on the Ti–13Nb–13Zr Alloy
    • Agnieszka Ossowska
    • Andrzej Zieliński
    • Jean-marc Olive
    • Andrzej Wojtowicz
    • Piotr Szweda
    2020 Full text Coatings

    The increasing demand for titanium and its alloys used for implants results in need of such innovative surface treatment that may jointly increase corrosion resistance and biocompatibility, and demonstrate antibacterial protection at no cytotoxicity. The purpose of this research was to characterize the effect of two-stage anodization, performed for 30 min in phosphoric acid, at the presence of hydrofluoric acid in the second stage. The scanning electron microscopy, atomic force microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, glow discharge optical emission spectroscopy, nanoindentation and nano-scratch tests, potentiodynamic corrosion studies, and water contact angle measurements were performed to characterize microstructure, mechanical, chemical and physical properties. The biological examinations were carried out to determine the cytotoxicity and antibacterial effects of oxide coatings. The research results demonstrate that two-stage oxidation affects several features and, in particular, improves mechanical and chemical behavior. The processes influencing the formation and properties of the oxide coating are discussed.

  • Initial Field Validation of Poroelastic Pavement Made with Crumb Rubber, Mineral Aggregate and Highly Polymer-Modified Bitumen
    • Piotr Jaskuła
    • Jerzy Ejsmont
    • Marcin Stienss
    • Grzegorz Ronowski
    • Cezary Szydłowski
    • Beata Świeczko-Żurek
    • Dawid Ryś
    2020 Full text Materials

    Tire/road noise in most driving conditions dominates other sources of traffic noise. One of the most efficient ways of reducing tire/road noise is to use the so-called “low noise pavement”. According to numerous studies, at present, poroelastic road pavement that is composed of rubber and mineral aggregate and polyurethane or bituminous binder gives the best noise reduction up to 12 dB. Unfortunately, there are many problems with making durable poroelastic pavements. This article presents the first results of a project that is executed in Poland and aims at the development of a durable, low noise poroelastic pavement based on polymer-modified asphalt binder called Safe, Eco-friendly POroelastic Road Surface (SEPOR). Two test sectionswere built in 2019 to test the production technology and performance of the SEPOR pavement. It is observed that some of the problems with previous poroelastic materials were mainly eliminated (especially delamination from the base layer and raveling) but noise reduction is a little less than expected (up to 9 dB). Rolling resistance for car tires is acceptable and fire properties (damping of spill fuel fires, toxic gas emission) are very good.

  • Innovation by proxy – clusters as ecosystems facilitating open innovation
    • Marita Mcphillips
    2020 Full text Journal of Entrepreneurship, Management and Innovation

    Open innovation is a concept, whose attributes can be perceived as naturally complementing the proximity-based offer of clusters. The purpose of this paper is to investigate the potential role of clusters as intermediaries of open innovation for cluster members. A literature review and an exploratory study were performed, involving in-depth interviews with experts in the field of innovation and clusters in Poland. This article conceptually links open innovation and clusters, proposes and categorizes roles of clusters as open innovation intermediaries, as well as indicates factors that might affect the successful adoption of this role. Furthermore, it points out that clusters could not only manage and mediate their network of members but also shape and co-create a broader open innovation ecosystem. The findings contribute to a comprehensive understanding of the potential roles of open innovation intermediaries in regard to clusters in the context of transitioning economies. With clusters playing the role of an open innovation intermediary, public support at cluster level could increase the openness to cooperation not only for member companies but all participants in the regional innovation ecosystem.

  • Innovative investment funds and stability of financial systems: Nonparametric study of exchange-traded funds in Europe
    • Adam Marszk
    2020

    The main aim of the paper is investigation of the potential contribution of exchange-trade funds (ETFs) to the instability of the European financial systems. The paper begins with presentation of the key theoretical concepts with regard to ETFs and financial stability. We discuss the key attributes of ETFs as the innovative category of investment funds, their hypothesized impact on the financial stability as well as briefly describe the European ETFs markets, focusing on the between-country differences. Subsequently, we present the results of our study, conducted by applying the selected composite index of the financial stress - Country-Level Index of Financial Stress (CLIFS) provided by the European Central Bank. The core indicator of the development of the ETFs markets is the turnover of the shares of ETFs on the local stock exchange (in order to facilitate comparisons all values are expressed in USD). Time period of the analysis is January 2004 - August 2017 and monthly data are used. Research methods include correlation and nonparametric analysis. Results of our analysis demonstrate that the threats to the European financial systems linked to the expansion of ETFs are minor, above all due to the low size of ETFs markets in most European economies. Moreover, for some ETFs markets with the highest turnover (such as United Kingdom) we identified the positive impact of ETFs to the stability of financial system.

  • Innovative rehabilitation lifts – mechanics in medical devices
    • Anna Czerwińska
    • Wojciech Głąb
    • Mariusz Deja
    • Dawid Zieliński
    2020 Full text Mechanik

    Mechanical devices are now widely used in physiotherapy and other rehabilitation processes. Particular importance is attached to devices enabling easy and effective transport of disabled people. The article presents innovative designs of rehabilitation lifts offered by the Polish manufacturer of lifts and medical accessories, LeviCare company. Moreover, the main assumptions of the research and development project implemented by the company, entitled “Development and testing of an innovative set for the transport and rehabilitation of disabled people on a European scale” are presented. A set of key tests that should be carried out for this type of medical-class devices is indicated.

  • Innovative Turbine Intake Air Cooling Systems and Their Rational Designing
    • Andrii Radchenko
    • Eugeniy Trushliakov
    • Krzysztof Kosowski
    • Dariusz Mikielewicz
    • Mykola Radchenko
    2020 Full text ENERGIES

    The improved methodology of the engine intake air cooling system designing based on the annual effect due to cooling was developed. It involves determining the optimal value of cooling capacity, providing the minimum system sizes at maximum rate of annual effect increment, and its rational value, providing a close to maximum annual effect without system oversizing at the second maximum rate of annual effect increment within the range beyond the first maximum rate. The rational value of design cooling capacity provides practically the maximum annual fuel saving but with the sizes of cooling systems reduced by 15 to 20% due to the correspondingly reduced design cooling capacity of the systems as compared with their values defined by traditional designing focused to cover current peaked short-term thermal loads. The optimal value of cooling capacity providing the minimum sizes of cooling system is very reasonable for applying the energy saving technologies, for instance, based on the thermal storage with accumulating excessive (not consumed) cooling capacities at lowered current thermal loads to cover the peak loads. The application of developed methodology enables revealing the thermal potential for enhancing the efficiency of any combustion engine (gas turbines and engines, internal combustion engines, etc.).

  • Innowacyjna metoda wzmocnienia gruntu za przyczółkiem przy użyciu iniekcji geopolimerowych
    • Anna Banaś
    • Lech Bałachowski
    • Andrzej Kuryłowicz
    • Agnieszka Poteraj-Oleksiak
    2020 Full text Builder

    W obecnych czasach szybki rozwój infrastruktury i nowoczesnych technologii niejednokrotnie narzuca projektantom oraz wykonawcom takie rozwiązania, aby prowadzone roboty budowalne, były jak najmniej uciążliwe dla uczestników ruchu i jak najmniej ingerowały w system komunikacyjny. Dotyczy to zarówno budowy nowych obiektów, jaki i remontu obiektów już istniejących. W niniejszej pracy przedstawiono nowatorską koncepcję remontu wiaduktu w ciągu Drogi Krajowej nr 12 nad torami PKP w miejscowości Podbór. Problemem, który występował podczas eksploatacji obiektu i prowadził do potrzeby pilnej oraz jak najmniej inwazyjnej jego naprawy było nadmierne osiadanie nasypu za przyczółkiem. Pierwszy raz w Polsce wykonano wzmocnienie gruntu za przyczółkiem wiaduktu przy użyciu iniekcji geopolimerowych, które w znaczący sposób skróciło czas ograniczenia w ruchu kołowym, a tym samym i czas samego remontu.