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  • Segmentation Quality Refinement in Large-Scale Medical Image Dataset with Crowd-Sourced Annotations
    • Tomasz Dziubich
    • Jan Cychnerski
    2021

    Deployment of different techniques of deep learning including Convolutional Neural Networks (CNN) in image classification systems has accomplished outstanding results. However, the advantages and potential impact of such a system can be completely negated if it does not reach a target accuracy. To achieve high classification accuracy with low variance in medical image classification system, there is needed the large size of the training data set with suitable quality score. This paper presents a study on the use of various consistency checking methods to refine the quality of annotations. It is assumed that tagging was done by volunteers (crowd-sourcing model). The aim of this work was to evaluate the fitness of this approach in the medical field and the usefulness of our innovative web tool designed to facilitate large-scale annotation of magnetic resonance (MR) images, as well as the accuracy of crowd-source assessment using this tool, comparing to expert classification. We present the methodology followed to annotate the collection of kidney MR scans. All of the 156 images were acquired from the Medical University of Gdansk. Two groups of students (with and without medical educational background) and three nephrologists were engaged. This research supports the thesis that some types of MR image annotations provided by naive individuals are omparable to expert annotation, but this process could be shortened in time. Furthermore, it is more costeffective in the simultaneous preservation of image analysis accuracy. With pixel-wise majority voting, it was possible to create crowd-sourced organ segmentations that match the quality of those created by individual medical experts (mAP up to 94% +/-3.9%).

  • Segmented bio-based polyurethane composites containing powdered cellulose obtained from novel bio-based diisocyanate mixtures
    • Ewa Głowińska
    • Paulina Kasprzyk
    • Janusz Datta
    2021 Pełny tekst WOOD SCIENCE AND TECHNOLOGY

    A considerable number of research works focus on the positive influence of cellulose on the properties of polymer-based composites and their wide range of application possibilities. The present work is focused on the synthesis of novel bio-based polyurethane (bio-PU) composites filled with powdered cellulose (microcellulose, MC) in an amount of 5 wt.%. Bio-PU composites were synthesized via a non-solvent prepolymer method. First, the prepolymer was synthesized from diisocyanate mixture based on hexamethylene diisocyanate and bio-based polyisocyanate Tolonate™ X Flo 100 and α,ω-oligo(ethylene-butylene adipate)diol which contained cellulose. Then, resulted prepolymer was extended by bio-based 1,4 butanediol (bio-BDO). Bio-PU composites were obtained with the different [NCO]/[OH] molar ratios: 0.95, 1.0, 105 and 1.1. Special attention was paid to the influence of MC on the phase separation between soft and hard segments of bio-PU by studying the chemical structure, morphology and thermal and mechanical properties of the prepared cellulose-based composites.

  • Seismic damage diagnosis in adjacent steel and RC MRFs considering pounding effects through improved wavelet-based damage-sensitive feature
    • Benyamin Mohebi
    • Omid Yazdanpanah
    • Farzin Kazemi
    • Antonio Formisano
    2021 Journal of Building Engineering

    This paper aims to propose complex Morlet (cmorfb-fc) wavelet-based refined damage-sensitive feature (rDSF) as a new and more precise damage indicator to diagnose seismic damages in adjacent steel and Reinforced Concrete (RC) Moment Resisting Frames (MRFs) assuming pounding conditions using acceleration responses. The considered structures include 6- and 9-story steel and 4- and 8-story RC benchmark MRFs that are assumed to have different values of separation distances, δMT, calculated according to the ASCE 7-10 seismic provision. For the sake of pounding modelling, linear viscoelastic contact elements among the pounding structures are assumed. Furthermore, an algorithm is developed to compute the seismic collapse capacities of each pounding MRF through Incremental Dynamic Analyses (IDA) using OpenSees software. In the next step, auto-regressive movingaverage with exogenous input (ARX) model together with a stabilization diagram is utilized to appraise the natural frequencies of each adjacent MRF. Shannon entropies and correlation coefficient (ρ) are used to select the best cmorfb-fc wavelet. Based on the results, damage resulting from pounding effects can be accurately detected in both cases of with and without δMT, especially for steel MRFs.

  • Seismic Pounding Between Bridge Segments: A State-of-the-Art Review
    • Mahmoud Miari
    • Kok Choong
    • Robert Jankowski
    2021 ARCHIVES OF COMPUTATIONAL METHODS IN ENGINEERING

    Earthquake-induced structural pounding in bridge structures has been observed in several previous seismic events. Collisions occur at the expansion joints provided between adjacent decks or between the deck and abutment. Pounding between the structural elements may lead to severe damages and even to the unseating of the bridge in certain cases. Several investigations have been performed to study pounding in bridges under uniform and non-uniform seismic excitations. Moreover, different mitigation measures have been suggested to overcome the drawbacks of this phenomenon. This work reviews previous research studies concerning earthquake-induced structural pounding in bridge structures, the factors that influence it and the recommended mitigation measures.

  • Selected Aspects of Pavement Texture Influence on Tire Rolling Resistance
    • Jerzy Ejsmont
    • Sławomir Sommer
    2021 Pełny tekst Coatings

    Tire rolling resistance has a significant influence on fuel consumption in cars and trucks and on CO2 emissions. Rolling resistance depends on the tire construction, pavement texture and stiffness, as well as environmental and traffic conditions. This article presents a pilot study on the impact of pavement texture on the rolling resistance of passenger car tires. Reasons why Mean Profile Depth is not a good descriptor of pavement characteristics from the point of view of rolling resistance are presented, and an experimental method which takes into account tire deformation on texture and partial enveloping is described. A method based on testing the volume and depth of tire tread deformation is also proposed.

  • Selected information technology tools supporting for maintenance and operation management electrical grids
    • Waldemar Kamrat
    2021 Pełny tekst Bulletin of the Polish Academy of Sciences-Technical Sciences

    The paper presents the main issues of management of electrical grids. Selected information technology tools supporting for electrical grids maintenance are presented. In electrical infrastructure maintenance of power companies the geographic information systems are increasingly used to support the management of theirs resources. Their functionalities in terms creating comprehensive databases for electrical infrastructure of power sector are described. The important information technology tools regarding spatial systems for supporting maintenance and operation management electrical grids and the conditions of their implementation are presented. This paper also attempts to innovative multidimensional evaluate the technical and economic benefits resulting from the use of modern information technology tools for the management of energy infrastructure.

  • Selected manufacturing difficulties encountered during setup of machining on cnc multi-axis linear automatic lathe and on cnc multi-spindle turning centers
    • Piotr Sender
    2021 Pełny tekst

    The article presents the observed manufacturing technology implementation difficulties in workshop practice, resulting from the construction and principles of operation on the DMG’s SPRINT 32/5 CNC linear automatic lathe and on the Mazak’s HQR 150 MSY and QTN 200 MS CNC turn - mill centers, and discusses possible rules for solving the production problems encountered. The article also discusses the principles of dividing the machining process and working steps on multi-spindle CNC turn - mill centers. It is worth to build a system supporting the selection of the sequence of treatments [1], taking into account the frequency of natural vibrations and stiffness obtained after each single machining operations. The article shows the method of verification of the selection of the machining planning method on CNC multi-spindle lathes.

  • Selected problems of decision making modelling in power engineering
    • Waldemar Kamrat
    2021 Pełny tekst Sustainable Energy Technologies and Assessments

    The paper presents the selected problems of decision making modelling in power engineering specially investment risk evaluation methods. The proposed model can be used in the range programming the development and investing process in power engineering. Decision making problems in power engineering and the evaluation of investment effectiveness in particular are closely related to modelling which relatively accurately reflects the complexity of market economy mechanisms. In order to analyze the phenomena mentioned above, models of existing processes, which are later used to achieve a set goal during decision making in a real situation, are applied. Its mathematical representation is a formalization of a model of a decision making task. A significant task in the whole process is to design a mathematical model, optimized by means of a goal function, whose arguments are decision variables meeting defined boundary conditions. Descriptions of decision making processes show that variables usually have non-negative values. Also the economic environment influences the quality of modelling. The dynamics of events causes that models of decision making processes can be analyzed. An attempt to take into account the influence of the factors mentioned above on the modelling of decision making in power engineering is presented in this paper.

  • Selection of an artificial pre-training neural network for the classification of inland vessels based on their images
    • Katarzyna Bobkowska
    • Izabela Bodus-olkowska Izabela
    2021 Pełny tekst Zeszyty Naukowe Akademii Morskiej w Szczecinie

    Artificial neural networks (ANN) are the most commonly used algorithms for image classification problems. An image classifier takes an image or video as input and classifies it into one of the possible categories that it was trained to identify. They are applied in various areas such as security, defense, healthcare, biology, forensics, communication, etc. There is no need to create one’s own ANN because there are several pre-trained networks already available. The aim of the SHREC projects (automatic ship recognition and identification) is to classify and identify the vessels based on images obtained from closed-circuit television (CCTV) cameras. For this purpose, a dataset of vessel images was collected during 2018, 2019, and 2020 video measurement campaigns. The authors of this article used three pre-trained neural networks, GoogLeNet, AlexNet, and SqeezeNet, to examine the classification possibility and assess its quality. About 8000 vessel images were used, which were categorized into seven categories: barge, special-purpose service ships, motor yachts with a motorboat, passenger ships, sailing yachts, kayaks, and others. A comparison of the results using neural networks to classify floating inland units is presented.

  • Selective monitoring of noise emitted by vehicles involved in road traffic
    • Andrzej Czyżewski
    • Tomasz Śmiałkowski
    2021 Pełny tekst Journal of the Acoustical Society of America

    An acoustic intensity probe was developed measures the sound intensity in three orthogonal directions, making possible to calculate the azimuth and elevation angles, describing the sound source position. The acoustic sensor is made in the form of a cube with a side of 10 mm, on the inner surfaces of which the digital MEMS microphones are mounted. The algorithm works in two stages. The first stage is based on the analysis of sound intensity signals, and it detects acoustic events. The second stage analyses a detection function based on the normalized source position; its task is to determine whether the acoustic event represents a vehicle passing the sensor and detecting its movement direction. The acoustic probes were mounted inside intelligent lamps that illuminate the roadways depending on the volume of traffic. The paper explains how accurately traffic can be monitored through directional noise analysis and shows the resulting application to smart cities.

  • Selenium enrichment in broccoli sprouts as an initial step in the preparation of Certified Reference Material
    • Chintankumar Padariya
    • Małgorzata Rutkowska
    • Piotr Konieczka
    2021 Pełny tekst

    Selenium is considered one of the essential elements in animals and humans. The main source of selenium intake for humans is the diet. Selenium deficiency has one of the most concerning issues worldwide. Broccoli sprouts are five-to-six-day old broccoli plants, and they may exhibit stronger chemoprotective effects. Thus, the enrichment of selenium in broccoli sprouts can enhance anticancer properties. As a result of conducted study, four batches of selenium enriched sprouts have been produced in order to verify the efficiency of selenium uptake by broccoli sprouts under commercial conditions. –1 Sodium selenite solution (10 mg L ) was used to prepare seleniumenriched broccoli sprouts. Sodium selenite is available for biological uptake by plants. The results might be different while the addition of sodium selenite in each step of the germination process could enhance the concentration of selenium in broccoli sprouts. Therefore, it could be potentially selected as a candidate for certified reference materials

  • Self Portrait with a Mask
    • Paweł Sasin
    2021 Pełny tekst Sztuka i Dokumentacja

    Paweł SASIN - Self Portrait with a Mask “Every work of art is the child of its time, and, in many cases, the mother of our emotions. “ Wassily Kandynsky, Concerning the Spiritual in Art The two years 2020 and 2021 were marked by the COVID-19 pandemic – a lengthy period of time in which everyone felt in danger of losing one’s health or life. As a result, many people were experiencing negative emotion, becoming subject to psychological stress: feeling anxious, fearful, frustrated, upset, depressed. In such situations, finding motivations to overcome these feelings is crucial and positive, as it helps people to overcome inactivity and achieve goals. During the phase of stress mobilization, one often experiences elevated efficiency of intellectual and cognitive processes: the ability to make associations and conceive unique ideas is enhanced, as well as one’s sensitivity to stimuli; which results in people accessing a greater range of their potential abilities (Frączek, Kofta, „Frustracja i stres psychologiczny”/ “Frustration and Psychological Stress”). What I am about to present is an attempt to address the question of the influence which the COVID-19 pandemic, as a socially challenging experience, may have had on the spontaneity and authenticity of creative imagination possessed by people studying architecture. Obligatory isolation, social distancing and other restraining regulations, dangers stemming from the infectious qualities of the disease, finally the huge number of gravely ill and deceased victims – those circumstance served as a trigger to ask architecture students at the Gdańsk University of Technology to create a piece on the topic Self Portrait with a Mask as part of their sculpture course.

  • Self-assembly of vertically oriented graphene nanostructures: multivariate characterisation by Minkowski functionals and fractal geometry
    • Mattia Pierpaoli
    • Mateusz Ficek
    • Paweł Jakóbczyk
    • Jakub Karczewski
    • Robert Bogdanowicz
    2021 Pełny tekst ACTA MATERIALIA

    The enormous self-assembly potential that graphene and its derived layered materials offer for responding to the contemporary environmental challenges has made it one of the most investigated materials. Hence, tuning its extraordinary properties and understanding the effect at all scales is crucial to tailoring highly customised electrodes. Vertically oriented graphene nanostructures, also known as carbon nanowalls (CNWs), due to the large surface area and unique maze-like morphology, have attracted attention as a platform for advanced sensing applications. In this work, a holistic investigation approach has been developed to disrupt the synthesis-composition-structure-property paradigm and to dig out the hidden materials relationships. To achieve that, autonomous advanced image-analysis methods (Minkowski Functionals, Fractal Analysis) have been applied to SEM micrographs and successfully classified them. Morphological, electrical, and electrochemical characterisation has been performed for all of the samples. Multivariate data analysis has been employed to mine the relationships between the material features, specifically as it relates to the understanding of the intrinsic properties. As a result, this study is intended to both shed light on CNWs as a promising transparent hybrid electrochemical substrate for perfectly assembled electrochemical devices and to provide a new flexible method for nanomaterial design, characterisation and exploitation.

  • Self-assembly, stability and conductance of amphotericin B channels: bridging the gap between structure and function
    • Joanna Zielińska
    • Miłosz Wieczór
    • Paweł Chodnicki
    • Ewa Grela
    • Rafał Luchowski
    • Łukasz Nierzwicki
    • Tomasz Bączek
    • Wiesław I. Gruszecki
    • Jacek Czub
    2021 NANOSCALE

    Amphotericin B (AmB), one of the most powerful but also toxic drugs used to treat systemic mycoses, is believed to selectively permeabilize fungal cell membranes to ions in a sterol-dependent manner. Unfortunately, the structure of the biologically active AmB channels has long eluded researchers, obstructing the design of safer alternatives. Here, we investigate the structural and thermodynamic aspects of channel formation, stability, and selective ion conduction. We combine fluorescence lifetime imaging and molecular simulations to trace the process of channel assembly until the formation of stable, roughly octameric double-length channels (DLCs). This stoichiometry is confirmed by matching the predicted channel conductances with the past results of patch-clamp measurements. We then use free energy calculations to explain the effect of sterols on DLC stability and discuss the observed cation selectivity in structural terms, addressing several long-standing controversies in the context of their physiological relevance. Simulations of ion permeation indicate that only solvated ions pass through DLCs, revealing surprising solvation patterns in the channel lumen. We conclude our investigation by inspecting the role of the tail hydroxyl in the assembly of functional channels, pointing at possible origins of the cholesterol–ergosterol selectivity.

  • Self-assessment of competencies of students and graduates participating in didactic projects – Case study
    • Małgorzata Gawrycka
    • Justyna Kujawska
    • Michał Tomczak
    2021 Pełny tekst International Review of Economics Education

    Aim/purpose: the aim of this article is to examine the opinions of students and graduates of the faculty of economics of a technical university as regards their selfassessment of their preparation for entering the modern labour market. All the respondents participated during their studies in didactic projects aimed at improving their competencies taking into account the expectations of potential employers. Design/methodology/approach: the study was quantitative in nature and was carried out using the CAWI method. In the analysis of the study results, elements of descriptive statistics were used, such as: mean measures, structure indicators, structure similarity indicators and tests for the significance of mean values. A comparative analysis was conducted between two groups of respondents – students and graduates. Findings: the conducted study shows that by organising additional training for students, the university contributes to supplementing their theoretical and practical knowledge in the area of competencies required by the labour market today, in particular within the scope of specialist and technical competencies which are becoming indispensable in the Economy 4.0. Research implications/limitations: due to the small size of the test sample, the results should be treated with caution, are not representative and constitute only a case study. Originality/value/contribution: the results of the research confirm the importance of lifelong learning as regards reducing the competence gap among university graduates. The tools used in the above-mentioned process include additional training activities, such as the presented didactic projects addressed to students, complementary to the curriculum of studies. They enabled the students to extend their competencies even before they left the walls of the university and, as a result, facilitated their entry into the labour market.

  • Self-employment of women: an opportunity or the last resort?
    • Dagmara Nikulin
    2021

    It is believed that automatization and technological changes will be the main drivers of work in the future. At the same time, there is a growing discussion about new forms of employment, such as self-employment. It may be either perceived as a chance for empowerment, through creating new job opportunities, that were not reachable previously, or as precarious work, with less stability, higher risk, and uncertain income. The main goal of this work is to analyze what makes women choose self-employment. Our cross-country study, conducted for 31 European countries based on 2014 European Labour Force Survey (LFS), brings a new perspective on the phenomenon. Our results suggest that self-employment may constitute an opportunity for women as higher level of skills and older age increase the probability of becoming self-employed. Moreover, as skilled people predominantly show greater skills related to the use of technology, one may conclude that the use of ICT may reinforce this form of work. On the other hand, self-employed women’s work is to a greater extent based on part-time arrangements and is frequently performed in the evenings. For this reason, it may be concluded that self-employment is an option for women who have to combine family life with work and have no chance to find typical paid employment.

  • Self-Organising map neural network in the analysis of electromyography data of muscles acting at temporomandibular joint.
    • Mateusz Troka
    • Wiktoria Wojnicz
    • Katarzyna Szepietowska
    • Izabela Lubowiecka
    2021

    The temporomandibular joint (TMJ) is the joint that via muscle action and jaw motion allows for necessary physiological performances such as mastication. Whereas mandible translates and rotates [1]. Estimation of activity of muscles acting at the TMJ provides a knowledge of activation pattern solely of a specific patient that an electromyography (EMG) examination was carried out [2]. In this work, a Self-Organising Maps (SOMs) based method was used to identify a hidden similarities in EMG data between different patients. Artificial Neural Network algorithm used for this work – Supervised Kohonen Network (SKN) was proposed and described in [3] and extended into a MATLAB toolbox by [4]. SKN algorithm was used to simulate the model, resulting in a chart called class profiles describing the calculated averages of the Kohonen weights of each variable. It shows how data similarity coming from different subjects is distributed. The obtained results let one to draw a conclusion about muscle significance during specific motion. This SOM based modelling method was intended to estimate TMJ instability and its muscle performance during jaw motions. The study was an attempt to identify and categorise patients with similarly possible disorders in TMJ area which can be evaluated from their muscles activation data.

  • Semantic segmentation training using imperfect annotations and loss masking
    • Adam Brzeski
    • Jan Cychnerski
    • Tomasz Dziubich
    • Tomasz Gilewicz
    • Jan Woś
    2021

    One of the most significant factors affecting supervised neural network training is the precision of the annotations. Also, in a case of expert group, the problem of inconsistent data annotations is an integral part of real-world supervised learning processes, well-known to researchers. One practical example is a weak ground truth delineation for medical image segmentation. In this paper, we have developed a new method of accurate segmentation of blood vessels based on a convolutional neural network. We focused on imperfect annotations for the semantic segmentation of blood vessels and introduced a concept of uncertainty masks and loss masking. These uncertainty masks can be created roughly by non-experts, which makes annotation process cheaper and faster. Quantitative results of our method on a real-world problem with missing annotations and on a perfectly labeled data set with artificially introduced noise are presented. Models trained with loss masking seem to be more robust regardless of the number of removed vessels. Noise robustness of four different model architectures has been tested and compared to the loss masking method, which turned out to have better performance during training on noisy data

  • SENSITIVITY ANALYSIS IN THE REHABILITATION OF HISTORIC TIMBER STRUCTURES ON THE EXAMPLES OF GREEK CATHOLIC CHURCHES IN POLISH SUBCARPATHIA
    • Katarzyna Szepietowska
    • Izabela Lubowiecka
    2021

    This work concerns structural and sensitivity analysis of carpentry joints used in historic wooden buildings in south-eastern Poland and western Ukraine. These are primarily sacred buildings and the types of joints characteristic for this region are saddle notch and dovetail joints. Thus, in the study the authors focus on these types of corner log joints. Numerical models of the joints are defined and finite element simulations of their statics are carried out. Moreover, a sensitivity analysis is performed in order to describe how the uncertainty of material properties including humidity of some structural members, caused during potential repairs, affect the structural behaviour of the whole connection. This represents the situation when some degraded logs are exchanged into new wood combining old, and often damp, wood with new and dry logs. A non-intrusive probabilistic approach to the sensitivity analysis is applied and regression-based Polynomial Chaos (PC) expansion method is used to propagate uncertainties.

  • Sensors and Sensor’s Fusion in Autonomous Vehicles
    • Andrzej Stateczny
    • Marta Wlodarczyk-Sielicka
    • Paweł Burdziakowski
    2021 Pełny tekst SENSORS

    Autonomous vehicle navigation has been at the center of several major developments, both in civilian and defense applications. New technologies such as multisensory data fusion, big data processing, and deep learning are changing the quality of areas of applications, improving the sensors and systems used. New ideas such as 3D radar, 3D sonar, LiDAR, and others are based on autonomous vehicle revolutionary development. The Special Issue entitled “Sensors and Sensor’s Fusion in Autonomous Vehicles” was focused on many aspects of autonomous vehicle sensors and their fusion, such as autonomous navigation, multi-sensor fusion, big data processing for autonomous vehicle navigation, sensors related to science/research, algorithms/technical development, analysis tools, synergy with sensors in navigation, and artificial intelligence methods for autonomous vehicle navigation.

  • Sequence-dependent structural properties of B-DNA: what have we learned in 40 years?
    • Gabriela da Rosa
    • Leandro Grille
    • Victoria Calzada
    • Katya Ahmad
    • Juan Pablo Arcon
    • Federica Battistini
    • Genís Bayarri
    • Thomas Bishop
    • Paolo Carloni
    • Thomas Cheatham III
    • Rosana Collepardo-Guevara
    • Jacek Czub
    • Jorge R. Espinosa
    • Rodrigo Galindo-Murillo
    • Sarah A. Harris
    • Adam Hospital
    • Charles Laughton
    • John H. Maddocks
    • Agnes Noy
    • Modesto Orozco
    • Marco Pasi
    • Alberto Pérez
    • Daiva Petkevičiūtė-Gerlach
    • Rahul Sharma
    • Ran Sun
    • Pablo D. Dans
    2021 Pełny tekst Biophysical Reviews

    The structure of B-DNA, the physiological form of the DNA molecule, has been a central topic in biology, chemistry and physics. Far from uniform and rigid, the double helix was revealed as a flexible and structurally polymorphic molecule. Conformational changes that lead to local and global changes in the helix geometry are mediated by a complex choreography of base and backbone rearrangements affecting the ability of the B-DNA to recognize ligands and consequently on its functionality. In this sense, the knowledge obtained from the sequence-dependent structural properties of B-DNA has always been thought crucial to rationalize how ligands and, most notably, proteins recognize B-DNA and modulate its activity, i.e. the structural basis of gene regulation. Honouring the anniversary of the first high-resolution X-ray structure of a B-DNA molecule, in this contribution, we present the most important discoveries of the last 40 years on the sequence-dependent structural and dynamical properties of B-DNA, from the early beginnings to the current frontiers in the field.

  • Series-Slot-Fed Circularly Polarized Multiple-Input-Multiple-Output Antenna Array Enabling Circular Polarization Diversity for 5G 28-GHz Indoor Applications
    • Ubaid Ullah
    • Muath Al-hasan
    • Ismail Mabrouk
    • Sławomir Kozieł
    2021 Pełny tekst IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION

    In this paper, a four-element circularly polarized series-slot-fed multiple-input-multiple-output (MIMO) antenna array with circular polarization diversity is presented. The proposed design utilizes a combination of 45-degree inclined slots and a straight microstrip line feeding technique. The two antennas are designed to operate with the opposite sense of circular polarization (CP). CP is achieved by placing a patch of just about square dimensions on the top of the V-slot with orthogonal but unequal arms. The unequal arm of the slot degenerates the fundamental mode at a slightly different frequency with 90-degree phase difference occurring at the center frequency of each arm. Proper positioning of the patch on the top of the slot ensures excitation of CP. For realizing a MIMO antenna with different sense of polarization, both the slots and the patches are flipped with respect to the feedline. Following optimization at the full-wave level of description, the antenna is prototyped and validated experimentally. The realizable antenna footprint is 20 mm × 27.7 mm. The simulated and measured results indicate that the proposed antenna features a wide impedance bandwidth (|S11|<-10 dB) from 26.9 GHz to 30.7 GHz, 3 dB axial ratio bandwidth from 27.31 GHz to 29.65 GHz and the peak realized gain of 11.86 dBic. Moreover, it exhibits a low level of in-band isolation |S21|>-37 dB and almost negligible envelope correlation coefficient (ECC), less than 0.00025. The highly directional beams, high gain and compact size of the proposed antenna permit implementation of multiple antennas for indoor applications in the 28-GHz band.

  • Serotonergic–Muscarinic Interaction within the Prefrontal Cortex as a Novel Target to Reverse Schizophrenia-Related Cognitive Symptoms
    • Paulina Cieślik
    • Adrianna Radulska
    • Grzegorz Burnat
    • Leszek Kalinowski
    • Joanna M. Wierońska
    2021 Pełny tekst INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

    Recent studies revealed that the activation of serotonergic 5-HT1A and muscarinic M1, M4, or M5 receptors prevent MK-801-induced cognitive impairments in animal models. In the present study, the effectiveness of the simultaneous activation of 5-HT1A and muscarinic receptors at preventing MK-801-induced cognitive deficits in novel object recognition (NOR) or Y-maze tests was investigated. Activators of 5-HT1A (F15599), M1 (VU0357017), M4 (VU0152100), or M5 (VU0238429) receptors administered at top doses for seven days reversed MK-801-induced deficits in the NOR test, similar to the simultaneous administration of subeffective doses of F15599 (0.05 mg/kg) with VU0357017 (0.15 mg/kg), VU0152100 (0.05 mg/kg), or VU0238429 (1 mg/kg). The compounds did not prevent the MK-801-induced impairment when administered acutely. Their activity was less evident in the Y-maze. Pharmacokinetic studies revealed high brain penetration of F15599 (brain/plasma ratio 620%), which was detected in the frontal cortex (FC) up to 2 h after administration. Decreases in the brain penetration properties of the compounds were observed after acute administration of the combinations, which might have influenced behavioral responses. This negative effect on brain penetration was not observed when the compounds were administered repeatedly. Based on our results, prolonged administration of a 5-HT1A activator with muscarinic receptor ligands may be effective at reversing cognitive decline related to schizophrenia, and the FC may play a critical role in this interaction.

  • Service-based Resilience via Shared Protection in Mission-critical Embedded Networks
    • Doganalp Ergenc
    • Jacek Rak
    • Mathias Fischer
    2021 Pełny tekst IEEE Transactions on Network and Service Management

    Mission-critical networks, which for example can be found in autonomous cars and avionics, are complex systems with a multitude of interconnected embedded nodes and various service demands. Their resilience against failures and attacks is a crucial property and has to be already considered in their design phase. In this paper, we introduce a novel approach for optimal joint service allocation and routing, leveraging virtualized embedded devices and shared backup capacity for the fault-tolerant design of mission-critical networks. This approach operates in phases utilizing multiple optimization models. Furthermore, we propose a new heuristic that ensures resource efficiency and fault-tolerance against single node and link failures as pre-requisite for resilience. Our experiments for different application scenarios indicate that our heuristic achieves results close to the optimum and provides 50% of capacity gain compared to a dedicated capacity protection scheme. Moreover, our heuristic ensures fault-tolerance against at least 90% of all potential single node failures.

  • Seven Different Lighting Conditions in Photogrammetric Studies of a 3D Urban Mock-Up
    • Katarzyna Bobkowska
    • Paweł Burdziakowski
    • Jakub Szulwic
    • Karolina Zielińska-Dąbkowska
    2021 Pełny tekst ENERGIES

    One of the most important elements during photogrammetric studies is the appropriate lighting of the object or area under investigation. Nevertheless, the concept of “adequate lighting” is relative. Therefore, we have attempted, based on experimental proof of concept (technology readiness level—TRL3), to verify the impact of various types of lighting emitted by LED light sources for scene illumination and their direct influence on the quality of the photogrammetric study of a 3D urban mock-up. An important issue in this study was the measurement and evaluation of the artificial light sources used, based on illuminance (E), correlated colour temperature (CCT), colour rendering index (CRI) and Spectral power distribution (SPD) and the evaluation of the obtained point clouds (seven photogrammetric products of the same object, developed for seven different lighting conditions). The general values of the quality of the photogrammetric studies were compared. Additionally, we determined seventeen features concerning the group of tie-points in the vicinity of each F-point and the type of study. The acquired traits were related to the number of tie-points in the vicinity, their luminosities and spectral characteristics for each of the colours (red, green, blue). The dependencies between the identified features and the obtained XYZ total error were verified, and the possibility of detecting F-points depending on their luminosity was also analysed. The obtained results can be important in the process of developing a photogrammetric method of urban lighting monitoring or in selecting additional lighting for objects that are the subject of a short-range photogrammetric study.

  • Shadow Economy in Poland Recent Evidence Based on Survey Data
    • Dagmara Nikulin
    • Ewa Lechman
    2021

    The book provides an estimate of the size of the shadow economy in Poland. Using analogous data, it traces core determinants of the existence of the shadow economy in Poland. It compares results with neighbouring countries, and if possible, the remaining Central-Eastern economies. The book tells why the problem of the unreported economic activity matters; it presents the problem from different angles―economic, social and institutional. Next, it extensively reviews past research on the size and determinants of the shadow economy in Poland. It discusses available resources and empirical results showing the problem from micro-, and macroeconomic perspective. The authors present the methods used and the results of the survey, which are interpreted and discussed Finally it concludes on major drivers of shadow economy in Poland, providing recommendations and future research directions. The book is intended for practitioners and those seeking understanding of undeclared economic activities.

  • Shaft friction from the DMT and direct shear interface tests
    • Kamila Mikina
    • Jakub Konkol
    • Lech Bałachowski
    2021

    The article presents preliminary attempt to create tri-linear transfer curves for describing pile behaviour under axial loading. Transfer curves would use the parameter measured in dilatometer test, particularly a constrained modulus MDMT. The proposed method is based on concrete rough and smooth interface tests performed in a direct shear apparatus. Based on the obtained mobilization curves, relationships were created between the parameters describing the slope of individual transfer curves and the MDMT modulus. The obtained correlations were used to estimate the capacity of the concrete screw pile subjected to the static load test in tension.

  • Shape and force control of cable structures with minimal actuators and actuation
    • Najmadeen Saeed
    • Ahmed Manguri
    • Abubakr Adabar
    2021 International Journal of Space Structures

    Shape adjustment and stress control can be considered as one of the effective parameters in prestressed cable structures since such structures are widely constructed nowadays due to their characteristics. The assembly errors and applied loads hugely affect the cables’ nodal positions and stress due to their delicacy. The former could disturb the shape, which affects the appearance and the function of the structure. In contrast, the latter may increase the stress in some cables above the upper limit or induce slack in some others. Accordingly, a technique has been proposed that combined fmincon optimization that relies on four different algorithms with a controlling approach based on the force method. The presented method aims to minimize the total amount of actuation and miniaturize the number of actuators. The targets of previously confirmed techniques can be obtained with less actuation and fewer actuators by using the current technique. Based on the verified examples, the advantage of the current approach over the quoted methods is up to 55% and 37% in terms of the number of actuators and the total amount of actuation, respectively.

  • Shape Memory Materials from Rubbers
    • Arunima Reghunadhan
    • Paduvilan Jibin
    • Vayyaprontavida Kaliyathan
    • Prajitha Velayudhan
    • Michał Strankowski
    • Sabu Thomas
    2021 Pełny tekst Materials

    Smart materials are much discussed in the current research scenario. The shape memory effect is one of the most fascinating occurrences in smart materials, both in terms of the phenomenon and its applications. Many metal alloys and polymers exhibit the shape memory effect (SME). Shape memory properties of elastomers, such as rubbers, polyurethanes, and other elastomers, are discussed in depth in this paper. The theory, factors impacting, and key uses of SME elastomers are all covered in this article. SME has been observed in a variety of elastomers and composites. Shape fixity and recovery rate are normally analysed through thermomechanical cycle studies to understand the effectiveness of SMEs. Polymer properties such as chain length, and the inclusion of fillers, such as clays, nanoparticles, and second phase polymers, will have a direct influence on the shape memory effect. The article discusses these aspects in a simple and concise manner.

  • Shape-Memory Polyurethane Polymers
    • Michał Strankowski
    • Paul Anju
    • Arunima Reghunadhan
    2021 Pełny tekst ACS SYMPOSIUM SERIES

    Polyurethanes (PUs) are one of the most widely used polymers in research and industry. They can be synthesized from chemical sources and natural sources. PUs are a very useful class of polymers and exhibit many desirable properties that can be exploited in various applications. PUs are formed by the reaction between polyols and isocyanates. A wide variety of polyols and isocyanates are available for synthesis, and hence we can produce a large number of PUs. PUs show high mechanical strength, chemical resistance, flexibility, and resilience. One of the major advantages of some specially designed PUs is their ability to recover their primary shape, which is known as shape memory. The shape-memory effect (SME) of PUs makes them popular in biomedical, electronic, and thermal applications. The SME can be monitored using different measures such as shape fixity, recovery time, and recovery rate. Various stimuli are applied to shape-memory materials to induce shape memory. PU polymers can be modified with different nanofillers, and these fillers influence the shape-recovery parameters. PU composites are popular because of a good property–price relationship. This chapter discusses the various factors affecting the SME of PU composites and the effect of different types of fillers on the PU matrix.

  • Shaping the City Responding to Climate Change – Concept of Development of the Right Bank of the Vistula River in Toruń, Poland,
    • Sylwia Sitniewska
    • Justyna Borucka
    2021

    The problems of cities of the 21st century are caused by anthropogenic oppression of the environment, through the growth of economic activity and continuous urbanisation, and taking away ecologically important open areas and biologically active areas. Increasingly frequent and sudden rains, strong winds, turbulence and rising world water levels are some of the consequences of climate change that have a direct impact on the functioning of cities. The article presents a study of a land-use plan for the right bank of the Vistula river in Toruń, Poland, in reference to ongoing climate change. The authors focus on the main assumption of this concept, which is to protect the area from increasing river floods expected due to strong climate change impact on Earth’s water cycle and temporary river water rise. The project strategy focussed on reshaping the Vistula river bank, as well as designing a solution that would allow floodwater to enter the area in a controlled manner. The newly designed area presented in the article is an attempt at conscious urban planning as well as planning activities in harmony with nature, and shows how such an approach to city planning can face the problems of climate change and could be a possible solution for future development of the city of Toruń.

  • Shear band evolution phenomena in direct shear test modelled with DEM.
    • Michał Nitka
    • Aleksander Grabowski
    2021 Pełny tekst POWDER TECHNOLOGY

    A direct shear test is widely used in the geotechnical engineering field. It is an easy and quick test to measure the shear properties of soil. This test often replaces more expensive and difficult tri-axial shear test. Despite that the direct shear test is known and used for a long time, it is still not well investigated at the grain scale. This paper deals with the micro behaviour of the cohesionless sand inside the direct shear box during a geotechnical test. Numerical calculations were performed with open-source discrete code YADE. The full 3D model was used, in order to eliminate some non-physical phenomena. The numerical stress-strain curve was directly compared with the laboratory results and good agreement was obtained. The focus was on the shape of the localized zone, the properties of this zone and its behaviour. The movement of the individual grains was studied. In our analysis, the stresses were also taken into consideration. The conclusions were validated on tests with different initial void ratio (dense or loose material) and with different vertical pressure.

  • Shear fracture of longitudinally reinforced concrete beams under bending using Digital Image Correlation and FE simulations with concrete micro-structure based on X-ray micro-computed tomography images
    • Łukasz Skarżyński
    • Ireneusz Marzec
    2021 Pełny tekst CONSTRUCTION AND BUILDING MATERIALS

    The paper presents experimental and numerical investigations of the shear fracture in rectangular concrete beams longitudinally reinforced with steel or basalt bar under quasi-static three point bending. Shear fracture process zone formation and development on the surface of beams was investigated by Digital Image Correlation (DIC) whereas thorough analyses of 3D material micro-structure, air voids, width and curvature of shear cracking were carried out by X-ray micro-computed tomography (micro-CT). Moreover, the 2D shear fracture patterns in beams were numerically simulated with the finite element method (FEM) using isotropic coupled elasto-plastic-damage constitutive model for concrete enhanced by a characteristic length of micro-structure. Concrete meso-structure was modelled as a random heterogeneous four-phase material composed of aggregate particles, cement matrix, ITZ zones and air voids on the basis of X-ray micro-CT images. Experimental and numerical results revealed a satisfactory agreement regarding to the mechanism of failure, load-bearing capacity as well as cracking pattern.

  • Short-Term Price Reaction to Filing for Bankruptcy and Restructuring Proceedings—The Case of Poland
    • Błażej Prusak
    • Marcin Potrykus
    2021 Pełny tekst Risks

    This study aims to check market reaction to filing for bankruptcy and restructuring proceedings and to verify the short-term effect of a price reversal in the Polish market in the years 2004–2019. The research was conducted by dividing the analysed companies according to the procedure (bankruptcy and restructuring) and market (the main market and the NewConnect market). The research methodology used in the study is the event analysis method (AR, CAR, AAR and CAAR rates were used in the research), with a few statistical tests (T-test, Generalized rank Z Test, Gen-eralized rank T-Test, Patell or Standardized Residual Test, Kolari and Pynnönen adjusted Patell or Standardized Residual Test). It was found that share prices in the Polish share market react quickly to public information about filing an application for bankruptcy or restructuring. For all analysed companies, the mean rate of return on the event day was equal to −14%, and on the next day, it was −3%. Regardless of the type of share market and the form of proceedings, the reversal effect was not confirmed in the short term. It was found that cumulative above-average rates of return fall more strongly for companies listed on the less liquid Newconnect market (−23.6%), and when information on the filing for bankruptcy proceedings is provided (−28.5%), as opposed to the main market (−19.1%) and restructuring proceedings (−17%). The cumulative average rate of return for all analysed companies in the research period (−2, +10 days) was equal to −20.6%.

  • Siderofory bakteryjne – rola w patogenezie i potencjał wykorzystania w diagnostyce
    • Beata Krawczyk
    • Aleksandra Rosińska
    2021 Pełny tekst

    Do prawidłowego funkcjonowania i wzrostu organizmów żywych zarówno ludzi, jak i bakterii niezbędne jest żelazo. Mikroelement ten występuje na dwóch różnych stopniach utlenienia: jako jon żelazawy (Fe2+) rozpuszczalny w roztworach fizjolo-gicznych oraz jako jon żelazowy (Fe3+), który nie tworzy roztworów wodnych [1]. Dzięki swoim właściwościom oksydo-redukcyjnym, żelazo wpływa na poprawne funkcjonowanie bardzo licznej grupy enzymów, m.in. cytochromów, oksydoreduktaz NADH-CoQ10, oksydoreduktazy bursztynianu-CoQ10. Enzymy te biorą udział w ważnych dla życia procesach metabolicznych, w czasie których produkowane są cząsteczki ATP. Bez udziału żelaza niemożliwe jest oddychanie. Żelazo wchodzi w skład hemoglobiny – białka transportującego tlen z płuc do wszystkich komórek w ludzkim organizmie. Ponadto bierze udział w neurogenezie, różnicowaniu komórek mózgu oraz jest kofaktorem licznych enzymów uczestniczących w syntezie neuro-przekaźników. W sytuacji niedoboru żelaza odpowiedź układu odpornościowego jest bardzo osłabiona [1, 2]. W komórkach bakteryjnych rola tego pierwiastka jest równie istotna i opiera się na zdolności jonów żelaza do utleniania i redukcji. Enzymy redoks znajdują się w cytozolu lub związane są z błoną komórkową, a jednym z ważniejszych jest reduktaza rybo-nukleotydowa – kluczowy enzym w procesie syntezy DNA. Ponadto jon żelazowy często jest końcowym akceptorem elektronów w łańcuchu oddechowym bakterii beztlenowych [3]. Do prawidłowego funkcjonowania i wzrostu komórka bakteryjna wymaga 10-7 M wolnych jonów żelazowych. W organizmie żywiciela bakteria musi zmierzyć się z bardzo ograniczonym dostępem do tego kluczowego pierwiastka. Większość komórko-wego żelaza gospodarza jest związana z jego białkami, a stężenie wolnych jonów żelaza we krwi jest o wiele za niskie do swobodnej dyfuzji. Aby zaspokoić zapotrzebowanie na ten mikroelement, mikroorganizmy produkują siderofory, czyli różnorodne che-micznie cząsteczki chelatujące jony i rozpoczynają konkurencję z gospodarzem o do-stępną pulę żelaza [3].

  • Sieci neuronowe oparte na prawach fizyki
    • Marek Moszyński
    • Bartłomiej Borzyszkowski
    • Karol Damaszke
    • Jakub Romankiewicz
    • Marcin Świniarski
    2021

    Wiele fizycznie nieuzasadnionych sieci neuronowych, mimo zadowalają- cej wydajności, generuje sprzeczności z logiką i prowadzi do rozbieżno- ści wyników z rzeczywistością. Jedną z metod poprawy funkcjonowania typowego modelu typu “black-box” na etapie uczenia, jest rozszerzenie jego funkcji kosztu o zależność bezpośrednio inspirowaną wzorem fizycz- nym. Niniejszy rozdział wyjaśnia koncepcję budowy sieci neuronowych opartych na prawach fizyki, zawiera przegląd zaproponowanych rozwią- zań w tej dziedzinie oraz opisuje możliwości implementacji funkcji strat wykorzystujących wzory fizyczne. Ponadto przedstawione badania poka- zują, że przewidywania algorytmów inspirowanych przez fizykę mogą być nie tylko optymalne, ale również naukowo spójne z równaniami dziedzi- nowymi. Ostatecznie wykorzystanie wiedzy naukowej zawartej w dosto- sowanych funkcjach kosztów pokazuje, że metodyka ta gwarantuje wy- niki spójne z prawami fizyki, a także lepszą generalizację w porównaniu z klasycznymi sieciami neuronowymi.

  • Signal Propagation in Electromagnetic Media Modelled by the Two-Sided Fractional Derivative
    • Jacek Gulgowski
    • Dariusz Kwiatkowski
    • Tomasz Stefański
    2021 Pełny tekst Fractal and Fractional

    In this paper, wave propagation is considered in a medium described by a fractional-order model, which is formulated with the use of the two-sided fractional derivative of Ortigueira and Machado. Although the relation of the derivative to causality is clearly specified in its definition, there is no obvious relation between causality of the derivative and causality of the transfer function induced by this derivative. Hence, causality of the system is investigated; its output is an electromagnetic signal propagating in media described by the time-domain two-sided fractional derivative. It is demonstrated that, for the derivative order in the range [1,+∞), the transfer function describing attenuated signal propagation is not causal for any value of the asymmetry parameter of the derivative. On the other hand, it is shown that, for derivative orders in the range (0,1), the transfer function is causal if and only if the asymmetry parameter is equal to certain specific values corresponding to the left-sided Grünwald–Letnikov derivative. The results are illustrated by numerical simulations and analyses. Some comments on the Kramers–Krönig relations for logarithm of the transfer function are presented as well.

  • Significant Production of Thermal Energy in Partially Ionized Hyperbolic Tangent Material Based on Ternary Hybrid Nanomaterials
    • Umar Nazir
    • Muhammas Sohail
    • Muhammad Bilal Hafeez
    • Marek Krawczuk
    2021 Pełny tekst ENERGIES

    Nanoparticles are frequently used to enhance the thermal performance of numerous materials. This study has many practical applications for activities that have to minimize losses of energy due to several impacts. This study investigates the inclusion of ternary hybrid nanoparticles in a partially ionized hyperbolic tangent liquid passed over a stretched melting surface. The fluid motion equation is presented by considering the rotation effect. The thermal energy expression is derived by the contribution of Joule heat and viscous dissipation. Flow equations were modeled by using the concept of boundary layer theory, which occurs in the form of a coupled system of partial differential equations (PDEs). To reduce the complexity, the derived PDEs (partial differential equations) were transformed into a set of ordinary differential equations (ODEs) by engaging in similarity transformations. Afterwards, the converted ODEs were handled via a finite element procedure. The utilization and effectiveness of the methodology are demonstrated by listing the mesh-free survey and comparative analysis. Several important graphs were prepared to show the contribution of emerging parameters on fluid velocity and temperature profile. The findings show that the finite element method is a powerful tool for handling the complex coupled ordinary differential equation system, arising in fluid mechanics and other related dissipation applications in applied science. Furthermore, enhancements in the Forchheimer parameter and the Weissenberg number are necessary to control the fluid velocity

  • Similarities and differences in the production of renewable energy in Central and Eastern Europe countries
    • Agnieszka Wałachowska
    2021

    Research background: In the era of climate change, environmental degradation, but also growing pub-lic awareness, there is a need to look for new ecological energy sources. This condition can be met by renewable energy sources (RES). The EU seeks to have a 32% share of its gross final energy consumption from renewable sources by 2030. While the EU as a whole is on course to meet its tar-gets, the question is if production of renewable energy at a given level is not a chal-lenge for selected Central and Eastern Europe countries (CEECs) trsdi-tionslly dependent on fossil fuels. In order to take steps to develop RES in the studied countries, there is a need to analyze their diversity in terms of the potential. The results of such analyses should support the implementation of adopted strate-gies. Purpose of the article: The article divides the CEECs into similar groups by the structure and volume of energy production from RES. This production was com-pared with the value of Gross Domestic Product (GDP) of each studied country, the number of in-habitants and its area. Methods: Cluster analysis. The research based on the data provided by Euro-stat. Findings & Value added: The division of the studied region into subgroups de-pends on how the RES energy production is related to the GDP value, the number of inhabitants and the area of individual country. This reference allows to reflect the specificity of individual countries in more appropriate way than just an analysis of the absolute values of this production. The applied approach allows for a broad-er look at RES production for selected countries in the region. The obtained results can be used for the development of a common energy and climate policy to create and develop their own renewable energy markets.

  • Simple 60 GHz Switched Beam Antenna for 5G Millimeter-Wave Applications
    • Kamil Trzebiatowski
    • Mateusz Rzymowski
    • Łukasz Kulas
    • Krzysztof Nyka
    2021 Pełny tekst IEEE Antennas and Wireless Propagation Letters

    A new 60 GHz band single-input switched beam antenna is proposed for the fifth-generation (5G) millimeter-wave network applications. The presented design is capable of electronically switching the main beam in two different directions via a proposed microstrip-line-to-slotline single-pole dual-throw (SPDT) switch based on commercially available p-i-n diodes. The antenna is fabricated in a low-cost printed circuit board process on a CuClad 217 substrate. Measurements were carried out in an anechoic chamber and experimental results show good agreement with numerical simulations. The antenna is capable of switching the main beam to the +45 $^\circ$ and −45 $^\circ$ directions in the horizontal plane with a gain of about 3 dBi and a beamwidth of 80 $^\circ$ in both states. The presented prototype shows several advantages over other state-of-the-art millimeter-wave reconfigurable antennas such as a simple electrical switching mechanism, low-cost manufacturing, a low profile, and a small footprint. These features make the presented antenna ideal for low-cost millimeter-wave 5G applications, particularly in end-devices working under the Internet-of-Things paradigm.

  • Simple SIR models with Markovian control
    • Krzysztof Bartoszek
    • Wojciech Bartoszek
    • Michał Krzemiński
    2021 Pełny tekst Japanese journal of statistics and data science

    We consider a random dynamical system, where the deterministic dynamics are driven by a finite-state space Markov chain. We provide a comprehensive introduction to the required mathematical apparatus and then turn to a special focus on the susceptible-infected-recovered epidemiological model with random steering. Through simulations we visualize the behaviour of the system and the effect of the high-frequency limit of the driving Markov chain. We formulate some questions and conjectures of a purely theoretical nature.

  • Simple sufficient condition for subspace to be completely or genuinely entangled
    • Maciej Demianowicz
    • Grzegorz Rajchel-Mieldzioć
    • Remigiusz Augusiak
    2021 Pełny tekst NEW JOURNAL OF PHYSICS

    We introduce a simple sufficient criterion, which allows one to tell whether a subspace of a bipartite or multipartite Hilbert space is entangled. The main ingredient of our criterion is a bound on the minimal entanglement of a subspace in terms of entanglement of vectors spanning that subspace expressed for geometrical measures of entanglement. The criterion is applicable to both completely and genuinely entangled subspaces. We explore its usefulness in several important scenarios. Further, an entanglement criterion for mixed states following directly from the condition is stated. As an auxiliary result we provide a formula for the generalized geometric measure of entanglement of the $d$--level Dicke states.

  • Simplified approach to assess the dynamic response of a container ship subjected to bow slamming load
    • Krzysztof Wołoszyk
    • Marian Bogdaniuk
    2021 Pełny tekst

    Simplified approach to assess the dynamic response of a container ship subjected to the bow slamming load, resulting in a transient vibratory response, typically called a 'whip-ping', is presented. The accurate numerical modelling is very complex and involves cou-pling of the hydrodynamic and structural solution at every time step, leading to huge com-putational and workload cost. Thus, the one-way coupling methodology is adopted, and hydrodynamic loads are derived using linear strip theory in the first step and applied to the FE beam model. Structural response is obtained in the time domain using an explicit dy-namic solver. Extreme bending moment is derived and compared with the normative val-ues of the wave-induced bending moment. Comparing to more accurate methods, the pre-sented approach seems to overestimate the bending moment and leads to a conservative design. Thus, it may be used in the early stages of the design, where fast and reliable methods are essential.

  • Simplified Method of Modelling Behaviour of Ship in Waves with Partially Flooded Compartments
    • Peter Szulczewski
    2021 Pełny tekst Transactions on Maritime Science-ToMS

    This paper contains a description of a numerical model for calculating behaviour of ships in waves. There are many models available, but the one described here can be characterised with a set of parameters that have a decisive impact on the final values of roll motion amplitude and frequency. In this paper, it is shown how a fitting of a standard-shape hull characterised by certain readily available parameters affects the final roll and frequency of the motion. In addition, calculations for a flooded tank were made, and a range of results for the maximum dynamic heeling forces from this tank is shown. This calculation can further be verified for a range of hull dimensions and geometries to present a viable method to the industry.

  • Simulation investigation of perovskite-based solar cells
    • Maciej Łuszczek
    • Grzegorz Łuszczek
    • Dariusz Świsulski
    2021 Pełny tekst Przegląd Elektrotechniczny

    Three models of thin-layer lead-halide perovskite solar cells with different electron-transport layers (TiO2,SnO2,ZnO) were investigatedby the simulation method. The perovskite layer thickness was optimized for all the systems. The analysis of the standard photovoltaic cell performanceparameters at various operating temperatures was performed. The best performance was achieved for the system with theSnO2conductive layer.

  • Simulation of the number of storm overflows considering changes in precipitation dynamics and the urbanisation of the catchment area: a probabilistic approach
    • Bartosz Szeląg
    • Roman Suligowski
    • Jakub Drewnowski
    • Francesco De Paola
    • Francisco-Jesus Fernandez-Morales
    • Łukasz Bąk
    2021 Pełny tekst JOURNAL OF HYDROLOGY

    This paper presents a probabilistic methodology that allows the study of the interactions between changes in rainfall dynamics and impervious areas in urban catchment on a long- and short-term basis. The proposed probabilistic model predict future storm overflows while taking into account the dynamics of changes in impervious areas and rainfall. In this model, a logistic regression method was used to simulate overflow resulting from precipitation events based on average rainfall intensity and impervious area. The adopted approach is universal (as it can be used in other urban catchments) and is a significant simplification of classic solutions; a hydrodynamic model is used to analyse the operation of the overflow. For the rainfall simulations, a rainfall generator based on the Monte Carlo method was used. In this method, a modification that allows the simulation of changes taking place in rainfall dynamics, including the effects of climate change, was introduced. This method provides the opportunity to expand and modify probabilistic models in which outflow from the catchment is modelled to predict the functioning of reservoirs and to design sewer networks that have the ability to deal with future rainfall dynamics, including moderate, strong, and violent downpours according to the Sumner scale. To verify the simulation results with a probabilistic model, an innovative concept using a hydrodynamic model was considered. This verification considers the changes in the impervious area in the period covered by the simulations and is limited using standard calculation procedures. In practice, the model presented in this work creates opportunities for defining the concept of sustainable development in urban catchments while taking into account the factors mentioned above. From the perspective of landscaping, this is important because it creates the opportunity to limit the impacts of climate change and area urbanization on the receiving waters.

  • Simulation Studies of Control Systems for Doubly Fed Induction Generator Supplied by the Current Source Converter
    • Paweł Kroplewski
    • Marcin Morawiec
    • Andrzej Jąderko
    • Charles Odeh
    2021 Pełny tekst ENERGIES

    The control system for a Doubly Fed Induction Generator (DFIG) supplied by a grid-connected Current Source Converter (CSC) is presented in this paper. Nonlinear transformation of DFIG model to the multi-scalar form is proposed. The nonlinear control strategy of active and reactive power of DFIG is realized by feedback linearization. In the proposed control scheme, the DFIG model and CSI parameters are included. Two Proportional-Integral (PI) controllers are dedicated for the control of the respective active and reactive powers. The control variables are the dc-link input voltage vector and the angular speed of the inverter output current. The proposed control approach is characterized by satisfactional dynamics and provides enhanced quality of the power transferred to the grid. In the simulation, evaluation of the characteristic operating states of the generator system, correctness of the feedback linearization and the dynamics of active and reactive power control loops are studied. Simulation results are adequately provided.

  • Simulator for Performance Evaluation of ASON/GMPLS Network
    • Sylwester Kaczmarek
    • Magdalena Młynarczuk
    2021 Pełny tekst IEEE Access

    The hierarchical control plane network architecture of Automatically Switched Optical Network with utilization of Generalized Multi-Protocol Label Switching protocols is compliant to next generation networks requirements and can supply connections with required quality of service, even with incomplete domain information. Considering connection control, connection management and network management, the controllers of this architecture could perform the same operations on the transport plane resources and could support control functions for Software Defined Networking controllers, which are considered as the future networking solutions. Therefore, it is very important to determine factors that have an influence on service control and resource management. One of the tools for achieving this goal is computer simulation. The paper proposes a simulator for the hierarchical control plane networks in an open source OMNeT++ environment, in order to evaluate network architecture performance for different network structures and traffic parameters. To demonstrate simulator capabilities, examples of typical simulations performance results for Polish and European network structures are presented and discussed. Performance metrics which have been used to evaluate the performance of this architecture are: mean values of Call Set-up Time, Connection Set-up Time, Call Release Time, Connection Release Time, loss probability for inter-domain connection requests and loss probability for low and high priority requests. General remarks concerned with presented simulator are also provided.

  • Simultaneous opto-electrochemical monitoring of carbamazepine and its electro-oxidation by-products in wastewater
    • Mattia Pierpaoli
    • Anna Dettlaff
    • Małgorzata Szopińska
    • Katarzyna Karpienko
    • Maciej Wróbel
    • Aneta Łuczkiewicz
    • Sylwia Fudala-Książek
    • Robert Bogdanowicz
    2021 Pełny tekst JOURNAL OF HAZARDOUS MATERIALS

    The growing human impact on aquatic environments, due to the extensive use of pharmaceuticals and the release of persistent pollutants, makes it necessary to implement new widespread methods for the characterisation and quantification of such contaminants and relative degradation products. Carbamazepine, 5H-dibenzo[b,f]azepine-5-carboxamide, (CBZ) is a widely used anti-epileptic drug, characterised by its limited removal by conventional wastewater treatments and high persistency in the environment. In this work, CBZ detection and quantification was performed in phosphate buffer as well as in samples of complex matrix like landfill leachates and treated wastewater originating from a medical facility, and simultaneously by optical and electrochemical methods using a novel transparent carbon-based nanostructured electrode. Coupling electrochemical (differential pulse voltammetry) with optical (UV-visible spectroscopy) methods, it has been possible to reach a limit of detection (LOD) for CBZ detection at the level of 4.7 μM for the electrochemical method, 10.3 μM for the spectroscopic method, and 3.6 μM for the opto-electrochemical method. Raman spectroscopy and ultra-high performance liquid chromatography coupled with tandem mass spectrometry techniques were employed to support and validate the combined technique. The novel developed technique showed high selectivity to carbamazepine and its by-products, even in environmental samples. Thus, this environmentally friendly, fast and accurate detection method is believed to be successfully implemented in the investigation of other pharmaceutical and chemical contaminates of concern.

  • Simultaneous Removal of Al, Cu and Zn Ions from Aqueous Solutions Using Ion and Precipitate Flotation Methods
    • Piotr Rybarczyk
    • Bożenna Kawalec-Pietrenko
    2021 Pełny tekst Processes

    This paper presents the results of investigations concerning the simultaneous removal of Al(III), Cu(II), and Zn(II) from dilute aqueous solutions using ion and precipitate flotation methods. The effects of initial solution pH, surface active substance concentration, and the gas velocity on the flotations’ efficiency and course are studied. Experimental results are discussed in terms of physicochemical aspects related to aqueous solutions of metal salts. The results indicate that satisfying simultaneous flotations of aluminum, copper and zinc species are observed if the pH value ranges between 7.0 and 9.0. It was found that an increase in collector concentration results in a decrease in the flotation rate constants. An increase in the gas velocity results in an increase in the ion and precipitate flotation rates.