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  • A Conformal Circularly Polarized Series-Fed Microstrip Antenna Array Design
    • Stanislav Ogurtsov
    • Sławomir Kozieł
    2020 Pełny tekst IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION

    A conformal circularly polarized series-fed microstrip array design for broadside radiation is presented. The array aperture under design is conformal to a cylindrical surface of a given radius. The approach we present primarily addresses focusing of the circularly polarized major lobe of the conformal array by proper dimensioning of the aperture spacings. The proposed analytical models yield the values of the element spacings within the series-fed conformal array aperture, and elementspecific spacings of the patch radiators within each circularly polarized element. These spacings are critical to produce a broadside circularly polarized major lobe at the design frequency. Subsequently, each array element is equipped with an in-line matching quarter wave transformer. Measured characteristics of the X-band conformal array validate the proposed design approach.

  • A continual model of a damaged medium used for analyzing fatigue life of polycrystalline structural alloys under thermal–mechanical loading
    • Ivan Volkov
    • Leonid Igumnov
    • Francesco dell'Isola
    • Svetlana Litvinchuk
    • Victor Eremeev
    2020 Pełny tekst CONTINUUM MECHANICS AND THERMODYNAMICS

    The main physical laws of thermal–plastic deformation and fatigue damage accumulation processes in polycrystalline structural alloys under various regimes of cyclic thermal–mechanical loading are considered. Within the framework of mechanics of damaged media, a mathematical model is developed that describes thermal–plastic deformation and fatigue damage accumulation processes under low-cycle loading. The model consists of three interrelated parts: relations defining plastic behavior of the material, accounting for its dependence on the failure process; evolutionary equations describing damage accumulation kinetics; a strength criterion of the damaged material. The plasticity model based on the notion of yield surface and the principle of orthogonality of the plastic strain vector to the yield surface is used as defining relations. This version of defining equations of plasticity describes the main effects of the deformation process under monotone cyclic, proportional and nonproportional loading regimes. The version of kinetic equations of damage accumulation is based on introducing a scalar parameter of damage degree and energy principles, and account for the main effects of nucleation, growth and merging of microdefects under arbitrary regimes of low-cycle loading. The strength criterion of the damaged material is based on reaching a critical value of the damage degree. The results of numerically modeling cyclic thermal–plastic deformation and fatigue damage accumulation in heat-resistant alloys (Nimonic 80A, Haynes 188) under combined thermal–mechanical loading are presented. Special attention is paid to the issues of modeling the processes of cyclic thermal–plastic deformation and fatigue damage accumulation for complex deformation processes accompanied by the rotation of the main stress and strain tensor areas. It is shown that the present damaged medium model accurately enough for engineering purposes describes the processes of cyclic isothermal and nonisothermal deformation and fatigue damage accumulation under combined thermal–mechanical loading and makes it possible to evaluate low-cycle fatigue life of heat-resistant alloys under arbitrary deformation trajectories.

  • A Critical Reanalysis of Uncontrollable Washboarding Phenomenon in Metal Band Sawing
    • Kazimierz Orłowski
    • Michał Dobrzyński
    • Grzegorz Gajowiec
    • Marcin Lackowski
    • Tomasz Ochrymiuk
    2020 Pełny tekst Materials

    The article analyzes the cutting process of hard bars. Investigations conducted in industrial conditions demonstrated the presence of surface errors in the machined workpieces in the form of washboard patterns. The purpose of this study was to analyze the results of cutting on band sawing machines with different band saw blades. The cutting processes were conducted on three different horizontal band sawing machine types. Analyzed material was an alloy steel Ø40 mm rod with a hardened surface covered with a thin layer of chromium. The hardness of the outer layer was 547 HV with a core hardness of 180 HV. The surface topography measurements of the processed workpieces were carried out with the 3D Optical Profiler, which supplied information on the irregularities of the processed material texture. In each of the analyzed cases, a corrugated surface was obtained after sawing, which is the effect of the occurrence of the washboarding phenomenon, despite the fact that the teeth of each band saw had variable pitches. The washboarding phenomenon when cutting rods with hard surfaces is caused by the phenomenon of wave regeneration. Despite the use of variable pitch saw blades, the cutting process results in rippling of the sawn surface, which is caused by the high hardness of the outer layer of the workpiece, as well as by the type of tool with spring setting of teeth.

  • A Development of a Capacitive Voltage Divider for High Voltage Measurement as Part of a Combined Current and Voltage Sensor
    • Roman Hrbac
    • Vaclav Kolar
    • Mikołaj Bartłomiejczyk
    • Tomas Mlcak
    • Petr Orsag
    • Jakub Vanc
    2020 Pełny tekst Elektronika Ir Elektrotechnika

    This article deals with the development of capacitive voltage divider for high voltage measurements and presents a method of analysis and optimization of its parameters. This divider is a part of a combined voltage and current sensor for measurements in high voltage power networks. The sensor allows continuous monitoring of the network distribution status and performs a quick diagnosis and location of possible network failures. Deployment of these devices will support semi-autonomous control of power networks and it can be considered as a step from traditional power grids toward smart grids. This is a worldwide trend connected with increasing number of renewable energy sources and plug-in electric vehicles as described in. In this way, it contributes to the reliability of the distribution network. Together with automated control techniques and fault location methods, it enables its self-healing capability. The following characteristics required for the sensor include: current measurement error up to 2 %, voltage measurement error up to 0.5 %, and power measurement error up to 5 %. At the same time, it is necessary that the sensor is cost-effective - relatively cheap. There were selected capacitors made in series production for the capacitive divider designing. The capacitive voltage divider was tested in terms of time and temperature stability; the results are described in the paper. Then, the method of mathematical correction of a temperature dependence of the capacitive voltage divider was suggested and tested.

  • A Finer Point on Vision
    • Karolina Zielińska-Dąbkowska
    2020 Lighting Design and Application

    As an IES Member, I look forward to each issue of LD+A and read them with great interest as they are often very informative. To my surprise, the Research article (May 2019, p. 76) has an error which should be corrected.

  • A five-year retrospective study shows increasing rates of antimicrobial drug resistance in Cabo Verde for both Staphylococcus aureus and Escherichia coli
    • Tamar Monteiro
    • Magdalena Wysocka
    • Elena Tellez
    • Ofelia Monteiro
    • Luzia Spencer
    • Elisa Veiga
    • Sandra Monteiro
    • Carine De Pina
    • Deisy Goncalves
    • Sandrine De Pina
    • Ludgero Correia
    • Joao Moreno
    • Teresa Conceicao
    • Marta Aires De Sousa
    • Herminia De Lencastre
    • Laura J Gray
    • Manish Pareek
    • David R Jenkins
    • Sandra Beleza
    • Marco R Oggioni
    • Isabel Ines Araujo
    2020 Pełny tekst Journal of Global Antimicrobial Resistance

    Objectives Data on baseline drug resistance is important in informing future antimicrobial stewardship programs. So far, no data on the antimicrobial drug resistance of clinical isolates was available for the African archipelago of Cabo Verde. Methods We have performed a retrospective analysis over five-years (2013-17) of the antimicrombial drug susceptibility profiles of clinical isolates in the two main hospitals of Cabo Verde. For Escherichia coli and Staphylococcus aureus, representing respectively 47% and 26% of all clinical isolates, the antimicrobial drug resistance profile was reported for six representative drugs. Results For E. coli we detected an increase in resistance to ampicillin, amoxicillin/clavulanic acid, ceftriaxone, ciprofloxacin, and trimethoprim-sulfamethoxazole and for S. aureus to methicillin, erythromycin and trimethoprim-sulfamethoxazole. This increase in both the most commonly isolated bacterial pathogens is of alarm as it might compromise empirical treatment in a setting with limited access to laboratory testing. Conclusions When compared to the published low resistance rates in carriage isolates, the more alarming situation in clinical isolates for S. aureus might encourage antimicrobial stewardship programs to reduce MRSA in the hospital settings, possibly as part of the Cabo Verdean national plan against antimicrobial drug resistance.

  • A Flexible Nafion Coated Enzyme‐free Glucose Sensor Based on Au‐dimpled Ti Structures
    • Adrian Olejnik
    • Katarzyna Siuzdak
    • Jakub Karczewski
    • Katarzyna Grochowska
    2020 ELECTROANALYSIS

    The detection of glucose at low concentrations using electrochemical sensors is of great importance due to the possibility of using different human body fluids than blood, such as e.g. urine, saliva, sweat or tears. The interest behind those biofluids is related to their utility in non-invasive sugar determination. In this work, we present flexible, fully biocompatible electrode material based on Au nanoparticles immobilized onto titanium dimples. Au Ti heterostructures were obtained via electrochemical anodization of titanium foil in presence of fluoride anions followed by chemical etching, magnetron sputtering of gold and subsequent thermal dewetting in continuous regime. In the last step of fabrication, electrodes were modified by permselective Nafion membrane. The selection of the best electrode material among different configurations was carried out basing on the electrochemical activity in the contact with 5 mM glucose dissolved in neutral air-saturated 0.1 M PBS. For the 10 nm Au dewetted gold film, limit of detection of 30 μM and high sensitivity of 93 mAcm 2mM 1 were achieved. Application of Nafion membrane caused complete inhibition of the impact of various interference species onto the glucose detection. Good selectivity and repeatability combined with the resistance to prolonged mechanical stress suggest that prepared material can be used in noninvasive glucose sensig

  • A framework for accelerated optimization of antennas using design database and initial parameter set estimation
    • Sławomir Kozieł
    • Adrian Bekasiewicz
    2020 Pełny tekst ENGINEERING COMPUTATIONS

    The purpose of this paper is to exploit a database of pre-existing designs to accelerate parametric optimization of antenna structures is investigated. Design/methodology/approach The usefulness of pre-existing designs for rapid design of antennas is investigated. The proposed approach exploits the database existing antenna base designs to determine a good starting point for structure optimization and its response sensitivities. The considered method is suitable for handling computationally expensive models, which are evaluated using full-wave electromagnetic (EM) simulations. Numerical case studies are provided demonstrating the feasibility of the framework for the design of real-world structures. Findings The use of pre-existing designs enables rapid identification of a good starting point for antenna optimization and speeds-up estimation of the structure response sensitivities. The base designs can be arranged into subsets (simplexes) in the objective space and used to represent the target vector, i.e. the starting point for structure design. The base closest base point w.r.t. the initial design can be used to initialize Jacobian for local optimization. Moreover, local optimization costs can be reduced through the use of Broyden formula for Jacobian updates in consecutive iterations. Research limitations/implications The study investigates the possibility of reusing pre-existing designs for the acceleration of antenna optimization. The proposed technique enables the identification of a good starting point and reduces the number of expensive EM simulations required to obtain the final design. Originality/value The proposed design framework proved to be useful for the identification of good initial design and rapid optimization of modern antennas. Identification of the starting point for the design of such structures is extremely challenging when using conventional methods involving parametric studies or repetitive local optimizations. The presented methodology proved to be a useful design and geometry scaling tool when previously obtained designs are available for the same antenna structure.

  • A framework for Air Quality Management Zones - Useful GIS-based tool for urban planning: Case studies in Antwerp and Gdańsk
    • Joanna Badach
    • Dimitri Voordeckers
    • Lucyna Nyka
    • Maarten Van Acker
    2020 Pełny tekst BUILDING AND ENVIRONMENT

    There is a growing recognition of the importance of proper urban design in the improvement of air flow and pollution dispersion and in reducing human exposure to air pollution. However, a limited number of studies have been published so far focusing on the development of standard procedures which could be applied by urban planners to effectively evaluate urban conditions with respect to air quality. To fill this gap, a new approach for the determination of urban Air Quality Management Zones (AQMZs) was proposed and presented based on two case studies: Antwerp, Belgium and Gdańsk, Poland. The main objectives of the study were to 1) formulate a theoretical framework for the management of urban ventilation potential and human exposure to air pollution and to 2) develop methods for its implementation by means of a geographic information system (GIS). As a result of the analysis, the typologies that may be associated with decreased ventilation potential and the areas that require close monitoring due to potential human exposure to air pollution were identified for both cities. It is advocated that delimiting these typologies – combined with investigating local climate, wind and topography conditions and air pollution characteristics – could constitute a preliminary step in the urban planning process aimed at air quality improvement. These methods can be further applied to other urban areas in order to indicate where detailed studies are required and to facilitate the development of planning guidelines. Moreover, the directions for further research and urban planning strategies were discussed.

  • A Framework for Enhancing Supplier Selection Process by Using SOEKS and Decisional DNA
    • Muhammad Ahmed
    • Cesar Sanin
    • Edward Szczerbicki
    2020 Pełny tekst Communications in Computer and Information Science

    Abstract. Supplier selection process is one of the significant stages in supply chain management for industrial manufactured products. It plays an integral role in the success of any manufacturing organization and is an important part starting right from selecting raw material to dispatch of finished products. This paper contributes to enhance the supplier selection process by proposing a multi-criteria decision making framework for industrial manufactured products. The proposed framework is based on smart knowledge management technique called Set of experience knowledge structure (SOEKS) and Decisional DNA, which makes the proposed approach dynamic in nature as it updates itself every time a decision is taken.

  • A global multinational survey of cefotaxime-resistant coliforms in urban wastewater treatment plants
    • Roberto Marano
    • Telma Fernandes
    • Celia M. Manaia
    • Olga Nunes
    • Donald Morrison
    • Thomas U. Berendonk
    • Norbert Kreuzinger
    • Tanel Telson
    • Gianluca Corno
    • Despo Fatta-Kassinos
    • Christophe Merlin
    • Edward Topp
    • Edouard Jurkevitch
    • Leonie Henn
    • Andrew Scott
    • Stefanie Hess
    • Katarzyna Slipko
    • Mailis Laht
    • Veljo Kisand
    • Andrea Di Cesare
    • Popi Karaolia
    • Stella G. Michael
    • Alice L Petre
    • Roberto Rosal
    • Amy Pruden
    • Virgina Riquemle
    • Ana Aguera
    • Belen Esterban
    • Aneta Łuczkiewicz
    • Agnieszka Kalinowska
    • Anne Leonard
    • William H. Gaze
    • Anthony A. Adegooke
    • Thor A. Stenstrom
    • Alfieri Pollice
    • Carlo Salerno
    • Carsten U. Schwermer
    • Paweł Krzemiński
    • Helene Guilloteau
    • Erica Donner
    • Barbara Drigo
    • Giovanni Libralato
    • Marco Guida
    • Helmut Burgmann
    • Karin Beck
    • Hemda Garelick
    • Marta Tacao
    • Isabel Henriques
    • Isabel Martinez-Alcala
    • Jose M. Guillien-Navarro
    • Magdalena Popowska
    • Marta Piotrowska
    • Markos Quintela-Baluja
    • Joshua T. Bunce
    • Maria I. Polo-Lopez
    • Samira Nahim-Granados
    • Marie-Noelle Pons
    • Milena Milakovic
    • Nikolina Udikovic-Kolic
    • Jerome Ory
    • Traore Ousmane
    • Pilar Caballero
    • Antoni Oliver
    • Sara Rodriguez-Mozaz
    • Jose L. Balcazar
    • Thomas Jager
    • Thomas Schwartz
    • Ying Yang
    • Shichun Zou
    • Yunho Lee
    • Younggun Yoon
    • Bastian Herzog
    • Heidrun Mayrhofer
    • Om Prakash
    • Yogesh Nimonkar
    • Ester Heath
    • Anna Baraniak
    • Joana Abreu-Silva
    • Manika Choudhury
    • Leonardo P. Munoz
    • Stela Krizanovic
    • Gianluca Brunetti
    • Ayella Maile-Moskowitz
    • Connor Brown
    • Eddie Cytryn
    2020 Pełny tekst ENVIRONMENT INTERNATIONAL

    The World Health Organization Global Action Plan recommends integrated surveillance programs as crucial strategies for monitoring antibiotic resistance. Although several national surveillance programs are in place for clinical and veterinary settings, no such schemes exist for monitoring antibiotic-resistant bacteria in the environment. In this transnational study, we developed, validated, and tested a low-cost surveillance and easy to implement approach to evaluate antibiotic resistance in wastewater treatment plants (WWTPs) by targeting cefotaxime-resistant (CTX-R) coliforms as indicators. The rationale for this approach was: i) coliform quantification methods are internationally accepted as indicators of fecal contamination in recreational waters and are therefore routinely applied in analytical labs; ii) CTX-R coliforms are clinically relevant, associated with extended-spectrum β-lactamases (ESBLs), and are rare in pristine environments. We analyzed 57 WWTPs in 22 countries across Europe, Asia, Africa, Australia, and North America. CTX-R coliforms were ubiquitous in raw sewage and their relative abundance varied significantly (<0.1% to 38.3%), being positively correlated (p < 0.001) with regional atmospheric temperatures. Although most WWTPs removed large proportions of CTX-R coliforms, loads over 103 colony-forming units per mL were occasionally observed in final effluents. We demonstrate that CTX-R coliform monitoring is a feasible and affordable approach to assess wastewater antibiotic resistance status.

  • A Highly Sensitive Planar Microwave Sensor for Detecting Direction and Angle of Rotation
    • Abhishek Jha
    • Adam Lamęcki
    • Michał Mrozowski
    • Bozzi Maurizio
    2020 Pełny tekst IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES

    This article presents a technique based on a modified complementary split-ring resonator (CSRR) to detect angular displacement and direction of rotation with high resolution and sensitivity over a wide dynamic range. The proposed microwave planar sensor takes advantage of the asymmetry of the sensor geometry and measures the angle of rotation in terms of the change in the relative phase of the reflection coefficients. The sensor consists of a movable modified CSRR (the rotor) and a microstrip line with a circular defect in the ground plane (the stator). By selecting the substrate material and the rotor thickness, the sensor can be designed to work at different operating frequencies. A theoretical model of the sensor is proposed and is followed by a detailed numerical analysis involving equivalent circuit simulations, full-wave computations, and measurement results. Using positioning error estimation and air-gap analysis, a technique based on phase-change measurements is found to be better than those based on magnitude measurements alone. The maximum sensitivity for measuring the angular rotation is found to be a 4.3◦ change in the relative phase of the reflection coefficient per 1◦ of rotation. The sensor has an angular measurement range from −90◦ to +90◦. The sensor—a stator fabricated on a 0.5-mm-thick Rogers RT5880 substrate and three rotors fabricated on a 1.5-mm-thick Rogers RT5880, a 1-mmthick FR4, and a 0.5-mm-thick Rogers RT5880—can effectively detect the direction of rotation, measure the angle of rotation and angular velocity with reasonable accuracy.

  • A literature survey of the influence of preform reheating and stretch blow molding with hot mold process parameters on the properties of PET containers. Part I.
    • Waldemar Karaszewski
    • Paweł Wawrzyniak
    2020 Pełny tekst Polimery

    The hot fill process is an inexpensive conventional filling technology for high-acidity products (pH < 4.5). It allows certain drinks (sensitive beverages such as fruit and vegetable juices, nectars, soft drinks, vitaminized water) to be stored at ambient temperature without the need for chemical preservatives. The primary feature of the bottles used in the hot fill process is their temperature stability, i.e. the ability to retain the shape of the bottle at the filling temperature. From a mechanical point of view, the thermal stability of PET bottles manufactured by the ISBM process is determined by the mechanical and thermal response of the blown preforms. From a microscopic point of view, the strongest influences on the mechanical and thermal properties of PET bottles are the orientation and crystallisation processes. From a technological point of view, the properties of PET bottles after manufacture by the stretch blow moulding process is mainly determined by the initial structure of the PET preform, the geometry and temperature distribution of the preform, the geometry of the blow mould and technological parameters of the blowing moulding process. The paper presents a wide analysis of the literature on the modified blow molding process with simultaneous stretching of PET material for storing hot filled drinks.

  • A literature survey of the influence of preform reheating and stretch blow moulding with hot mould process parameters on the properties of PET containers – part 2.
    • Waldemar Karaszewski
    • Paweł Wawrzyniak
    2020 Pełny tekst Polimery

    The hot fill process is an inexpensive conventional filling technology for high-acidity products (pH < 4.5). It allows certain drinks (sensitive beverages such as fruit and vegetable juices, nectars, soft drinks, vitaminised water) to be stored at ambient temperature without the need for chemical preservatives. The primary feature of the bottles used in the hot fill process is their temperature stability, i.e. the ability to retain the shape of the bottle at the filling temperature. From a mechanical point of view, the thermal stability of PET bottles manufactured by the ISBM process is determined by the mechanical and thermal response of the blown preforms. From a microscopic point of view, the strongest influences on the mechanical and thermal properties of PET bottles are the orientation and crystallisation processes. From a technological point of view, the properties of PET bottles after manufacture by the stretch blow moulding process is mainly determined by the initial structure of the PET preform, the geometry and temperature distribution of the preform, the geometry of the blow mould and technological parameters of the blowing moulding process. The paper presents a wide analysis of the literature on the modified blow molding process with simultaneous stretching of PET material for storing hot filled drinks.

  • A Loophole of All ‘Loophole-Free’ Bell-Type Theorems
    • Marek Czachor
    2020 Pełny tekst Foundations of Science

    Bell’s theorem cannot be proved if complementary measurements have to be represented by random variables which cannot be added or multiplied. One such case occurs if their domains are not identical. The case more directly related to the Einstein–Rosen–Podolsky argument occurs if there exists an ‘element of reality’ but nevertheless addition of complementary results is impossible because they are represented by elements from different arithmetics. A naive mixing of arithmetics leads to contradictions at a much more elementary level than the Clauser–Horne–Shimony–Holt inequality.

  • A Measurable Selector in Kadison’s Carpenter’s Theorem
    • Marcin Bownik
    • Marcin Szyszkowski
    2020 Pełny tekst CANADIAN JOURNAL OF MATHEMATICS-JOURNAL CANADIEN DE MATHEMATIQUES

    We show the existence of a measurable selector in Carpenter’s Theorem due to Kadison. This solves a problem posed by Jasper and the first author in an earlier work. As an application we obtain a characterization of all possible spectral functions of shift-invariant subspaces of L 2 (R d ) and Carpenter’s Theorem for type I ∞ von Neumann algebras.

  • A measurement method for capacitive sensors based on a versatile direct sensor-to-microcontroller interface circuit
    • Zbigniew Czaja
    2020 Pełny tekst MEASUREMENT

    In the paper, there is presented a new time-domain measurement method for determining the capacitance values of capacitive sensors, dedicated, among others, to capacitive relative humidity sensors. The method is based on a versatile direct sensor-to-microcontroller interface for microcontrollers with internal analog comparators (ACs) and with precision voltage reference sources, e.g. digital-to-analog converters (DACs). The reference source can be replaced by a resistive divider attached to the negative input of the AC. The interface circuit consists only of a reference resistor Rr, a given capacitive sensor working as a voltage divider, and a microcontroller (its peripherals: AC, timer, DAC, I/O pins). A prototype of the proposed complete solution of a compact capacitive smart sensor based on an 8-bit ATXmega32A4 microcontroller has been developed and tested. The maximum possible relative inaccuracy of an indirectly measurable capacitance was analysed, and experimental research was also performed. The results confirmed that the relative errors of value determination for a capacitive sensor are less than ±0.06%, which corresponds to a capacitance measurement accuracy of less than 0.1 pF for a range of measured capacity values from 100 pF to 225 pF, which in turn corresponds to at least a 0.5% relative humidity resolution for commercial capacitive RH sensors (e.g. TE Connectivity HS1101LF and Philips H1).

  • A modelling approach to the transport support for the harvesting and transportation complex under uncertain conditions
    • Ievgen Medvediev
    • Peter Eliseyev
    • Iryna Lebid
    • Olha Sakno
    2020 Pełny tekst IOP Conference Series: Materials Science and Engineering

    The article proposes a modelling approach based on structural and parametric identification of the transport support of the harvesting and transportation complex. The efficiency and effectiveness of the proposed methods of structural and parametric identification for the development of a system for harvesting and transportation complex operation has been proved. A mathematical model based on fuzzy logic has been developed. It reflects the interaction and interference of the weather-climatic, technical and technological parameters of transport support and its elements. A simulation method of transport support for harvesting and transport complex has been developed. The basis of the method is an algorithm for constructing a flow chart for the transport system operation consisting of structural and parametric identification levels and a mathematical model for the winter wheat harvesting transportation. A special feature of the method is the consideration of the weather-climatic, technical and technological parameters of the harvesting-transportation complex.

  • A new concept of PWM duty cycle computation using the Barycentric Coordinates in a Three-Dimensional voltage vectors arrangement
    • Paweł Szczepankowski
    • Nikolai Poliakov
    • Denis Vertegel
    • Krzysztof Szwarc
    • Ryszard Strzelecki
    2020 Pełny tekst IEEE Access

    The paper presents a novel approach to the Pulse Width Modulation (PWM) duty cycle computing for complex or irregular voltage vector arrangements in the two (2D) and three–dimensional (3D) Cartesian coordinate systems. The given vectors arrangement can be built using at least three vectors or collections with variable number of involved vectors (i.e. virtual vectors). Graphically, these vectors form a convex figure, in particular, a triangle or a tetrahedron. The reference voltage vector position inside that figure can be expressed by the barycentric coordinates, which are calculated using the second (2D case) or the third–degree determinant (3D case) – without trigonometry and angles. Thus, the speed of the PWM duty cycle computation rises significantly. The use of the triangle area or the tetrahedron volume, instead of the standard vector projection also permits for a well–defined and universal approach to identifying the reference vector position, especially for converters with complex and/or deformed space–vector diagrams (i.e. floating DC–link, multisource DC–link). The proposed computation scheme is based on simple instructions without trigonometry thereby, the DSP processor, or digital solution for field–programmable gate array, can fast–perform this operation using atomic operations. The aim of the presented considerations is not a novel PWM modulation, but a computable idea of a general calculation scheme for cases in which the distribution of vectors is non-trivial. A detailed algebraic and geometric analysis, as well as mathematical proofs on the total consistency of the results with the standard projection method, are also included. Subsequently, the Three–Dimensional Space Vector Modulation (3D–SVM), is considered as a special background to present a novel approach.

  • A new construction of shell-and-tube heat exchanger with impinging jets and minichannels technologies for heat recovery from gases – experimental analysis
    • Jan Wajs
    • Roksana Bochniak
    • Aleksandra Gołąbek
    • Tomasz Kura
    2020

    A dynamic development of technologies allowing waste heat utilization is observed in a correspondence with a pro-ecological approach of the zero waste idea. Such approach becomes the most demanding in the area of low-temperature was heat sources, especially gaseous media. Till now, they were usually not utilized due to unfavorable thermal conditions and high costs. Therefore, the zero waste approach directs research on techniques for heat exchange intensification and increasing heat transfer coefficients. In many cases, it is connected with the compact heat exchangers oriented on the low-temperature heat recovery from gaseous sources. Passive intensification methods, characterized by low energy consumption are primarily desirable. The shell-and-tube heat exchanger is a type of commonly applied unit in various industry branches, that is why it is considered as the most suitable for improvements. The passive techniques, implemented in it, are very often connected with various types of inserts in the bundle of tubes, which intensify the heat exchange process on the gas side and are a relatively simple modification even of existing heat exchangers. The inserts are of various shapes, optimized toward particular applications and sometimes combined with other techniques. Following the pro-ecological approach, the authors proposed an innovative shell-and-tube heat exchanger a new type of inserts, designed to transfer high heat fluxes. Proposed construction based on the previous experiences with the impinging jets technology, which confirmed its validity in the cylindrical heat exchangers. Novelty of the tube inserts relies on generation of jets impinging on the heat exchange surface. To enhance a compactness of the heat exchanger, the minichannels technology was also implemented - the inlet diameter of single perforated tube is 2 mm. In this paper the construction and principles of operation of described shell-and-tube heat exchanger were discussed. The experimental stand and investigations of heat exchanger thermal performance in a single-phase convection in the gas-liquid system were presented. Analysis of obtained data provides the basis for further development of a correlation describing the Nusselt number for shell-and-tube heat exchangers with impinging jet technique.

  • A new hyperbolic-polynomial higher-order elasticity theory for mechanics of thick FGM beams with imperfection in the material composition
    • Mohammad Malikan
    • Victor Eremeev
    2020 Pełny tekst COMPOSITE STRUCTURES

    A drawback to the material composition of thick functionally graded materials (FGM) beams is checked out in this research in conjunction with a novel hyperbolic‐polynomial higher‐order elasticity beam theory (HPET). The proposed beam model consists of a novel shape function for the distribution of shear stress deformation in the transverse coordinate. The beam theory also incorporates the stretching effect to present an indirect effect of thickness variations. As a result of compounding the proposed beam model in linear Lagrangian strains and variational of energy, the system of equations is obtained. The Galerkin method is here expanded for several edge conditions to obtain elastic critical buckling values. First, the importance of the higher‐order beam theory, as well as stretching effect, is assessed in assorted tabulated comparisons. Next, with validations based on the existing and open literature, the proposed shape function is evaluated to consider the desired accuracy. Some comparative graphs by means of well‐known shape functions are plotted. These comparisons reveal a very good compliance. In the final section of the paper, based on an inappropriate mixture of the SUS304 and Si3C4 as the first type of FGM beam (Beam‐I) and, Al and Al2O3 as the second type (Beam‐II), the results are pictured while the beam is kept in four states, clamped–clamped (C–C), pinned–pinned (S–S), clamped-pinned (C–S) and in particular cantilever (C–F). We found that the defect impresses markedly an FGM beam with boundary conditions with lower degrees of freedom.

  • A new look at the statistical identification of nonstationary systems
    • Maciej Niedźwiecki
    • Marcin Ciołek
    • Artur Gańcza
    2020 Pełny tekst AUTOMATICA

    The paper presents a new, two-stage approach to identification of linear time-varying stochastic systems, based on the concepts of preestimation and postfiltering. The proposed preestimated parameter trajectories are unbiased but have large variability. Hence, to obtain reliable estimates of system parameters, the preestimated trajectories must be further filtered (postfiltered). It is shown how one can design and optimize such postfilters using the basis function framework. The proposed solution to adaptive tuning of postfilter settings is based on parallel estimation and cross-validatory analysis. When compared with the classical solutions to the problem of parameter tracking, the new approach offers, without compromising good tracking performance, significant computational savings, higher numerical robustness and greater flexibility.

  • A New Method of Noncausal Identification of Time-varying Systems
    • Maciej Niedźwiecki
    • Marcin Ciołek
    • Artur Gańcza
    • Piotr Kaczmarek
    2020 Pełny tekst

    The paper shows that the problem of noncausal identification of a time-varying FIR (finite impulse response) sys- tem can be reformulated, and solved, as a problem of smoothing of the preestimated parameter trajectories. Characteristics of the smoothing filter should be chosen so as to provide the best trade- off between the bias and variance of the resulting estimates. It is shown that optimization of the smoothing operation can be performed adaptively using the parallel estimation technique.

  • A nontargeted approach to determine the authenticity of Ginkgo biloba L. plant materials and dried leaf extracts by liquid chromatography-high-resolution mass spectrometry (LC-HRMS) and chemometrics
    • Meryl Cruz
    • Benjamin J. Place
    • Laura J. Wood
    • Aaron Urbas
    • Andrzej Wasik
    • Werickson Fortunato de Carvalho Rocha
    2020 Pełny tekst ANALYTICAL AND BIOANALYTICAL CHEMISTRY

    The lack of stringent regulations regarding raw materials for herbal supplements used for medicinal purposes has been a constant challenge in the industry. Ginkgo biloba L. leaf extracts attract consumers because of the supposed positive effect on mental performance and memory. Supplements are produced using dried leaf materials and standardized leaf extracts such as EGb 761. Adulteration of Ginkgo biloba L. plants and extracts are becoming more and more common practice due to economically driven motivation from increasing demand in the market and the high cost of raw materials and production. Reinforcement in quality control (QC) to avoid adulterations is necessary to ensure the efficacy of the supplements. In this study, liquid chromatographyhigh-resolution mass spectrometry (LC-HRMS) was used with principal component analysis (PCA) as an unsupervised exploratory method to analyze, identify, and evaluate the adulterated Ginkgo biloba L. plant materials and dried leaf extracts using the PCA scores and loadings obtained and compound identification.

  • A note on polynomial algorithm for cost coloring of bipartite graphs with Δ ≤ 4
    • Krzysztof Giaro
    • Marek Kubale
    2020 Pełny tekst Discussiones Mathematicae Graph Theory

    In the note we consider vertex coloring of a graph in which each color has an associated cost which is incurred each time the color is assigned to a vertex. The cost of coloring is the sum of costs incurred at each vertex. We show that the minimum cost coloring problem for n-vertex bipartite graph of degree ∆≤4 can be solved in O(n^2) time. This extends Jansen’s result [K.Jansen,The optimum cost chromatic partition problem, in: Proc. CIAC’97,Lecture Notes in Comput. Sci. 1203 (1997) 25–36] for paths and cycles to subgraphs of biquartic graphs.

  • A novel concept of negative CO2 emission power plant for utilization of sewage sludge
    • Paweł Ziółkowski
    • Janusz Badur
    • Halina Pawlak-kruczek
    • Lukasz Niedzwiecki
    • Mateusz Kowal
    • Krystian Krochmalny
    2020

    Carbon Capture and Storage (CSS) technology is considered an important “bridge technology”, allowing effective abatement of CO2 emissions for power units using fossil fuels. However, if biomass is used in a power plant, equipped with CCS system, negative CO2 emissions can be achieved. In practice, wide development of such technologies would enable not only reduction of CO2 emissions, but also reversal of the harm done so far. In the long term, wide application of technologies with carbon-negative emissions could allow coming back to pre-industrial concentrations of CO2 in the atmosphere. Sewage sludge is a residue of the wastewater processing, that is a biologically active and consists of water, organic matter, including dead and alive pathogens, as well as organic and inorganic contaminants such as polycyclic aromatic hydrocarbons (PAHs) and heavy metals. Due to the nature of sewage sludge and its possible influence on human health and wellbeing, it is a subject of various regulations. Currently, sewage sludge is considered a biomass, according to the new Polish act on renewable energy sources from 20th of February 2015 and its novel version from 19th of July 2019. This study presents a novel approach, that aims at assessing feasibility of the concept of a negative CO2 emission power plant, based on steam gasification of sewage sludge, subsequent combustion of the producer gas in a gas turbine with spray-ejector condenser. This novel solution offers an efficient way to convert the chemical energy in the sewage sludge and, in the same time, compress and capture CO2. Possibility to utilize sewage sludge is an additional advantage of the proposed solution. For example: composition and calorific value of the dry producer gas, determined experimentally, are as follows: YCO=0.133; YCO2=0.593; YCH4=0.117; YCnHm=0.08; YH2=0.051 and LHV=16.43 MJ/kg.

  • A Novel Method for the Deblurring of Photogrammetric Images Using Conditional Generative Adversarial Networks
    • Paweł Burdziakowski
    2020 Pełny tekst Remote Sensing

    The visual data acquisition from small unmanned aerial vehicles (UAVs) may encounter a situation in which blur appears on the images. Image blurring caused by camera motion during exposure significantly impacts the images interpretation quality and consequently the quality of photogrammetric products. On blurred images, it is difficult to visually locate ground control points, and the number of identified feature points decreases rapidly together with an increasing blur kernel. The nature of blur can be non-uniform, which makes it hard to forecast for traditional deblurring methods. Due to the above, the author of this publication concluded that the neural methods developed in recent years were able to eliminate blur on UAV images with an unpredictable or highly variable blur nature. In this research, a new, rapid method based on generative adversarial networks (GANs) was applied for deblurring. A data set for neural network training was developed based on real aerial images collected over the last few years. More than 20 full sets of photogrammetric products were developed, including point clouds, orthoimages and digital surface models. The sets were generated from both blurred and deblurred images using the presented method. The results presented in the publication show that the method for improving blurred photo quality significantly contributed to an improvement in the general quality of typical photogrammetric products. The geometric accuracy of the products generated from deblurred photos was maintained despite the rising blur kernel. The quality of textures and input photos was increased. This research proves that the developed method based on neural networks can be used for deblur, even in highly blurred images, and it significantly increases the final geometric quality of the photogrammetric products. In practical cases, it will be possible to implement an additional feature in the photogrammetric software, which will eliminate unwanted blur and allow one to use almost all blurred images in the modelling process.

  • A Parallax Shift Effect Correction Based on Cloud Height for Geostationary Satellites and Radar Observations
    • Tomasz Bieliński
    2020 Pełny tekst Remote Sensing

    The effect of cloud parallax shift occurs in satellite imaging, particularly for high angles of satellite observations. This study demonstrates new methods of parallax effect correction for clouds observed by geostationary satellites. The analytical method that could be found in literature, namely the Vicente et al./Koenig method, is presented at the beginning. It approximates a cloud position using an ellipsoid with semi-axes increased by the cloud height. The error values of this method reach up to 50 meters. The second method, which is proposed by the author, is an augmented version of the Vicente et al./Koenig approach. With this augmentation, the error can be reduced to centimeters. The third method, also proposed by the author, incorporates geodetic coordinates. It is described as a set of equations that are solved with the numerical method, and its error can be driven to near zero by adjusting the count of iterations. A sample numerical solution procedure with application of the Newton method is presented. Also, a simulation experiment that evaluates the proposed methods is described in the paper. The results of an experiment are described and contrasted with current technology. Currently, operating geostationary Earth Observation (EO) satellite resolutions vary from 0.5 km up to 8 km. The pixel sizes of these satellites are much greater than for maximal error of the least precise method presented in this paper. Therefore, the chosen method will be important when the resolution of geostationary EO satellites reaches 50 m. To validate the parallax correction, procedure data from on-ground radars and the Meteosat Second Generation (MSG) satellite, which describes stormy events, was compared before and after correction. Comparison was performed by correlating the logarithm of the cloud optical thickness (COT) with radar reflectance in dBZ (radar reflectance – Z in logarithmic form).

  • A pilot study to assess an in-process inspection method for small diameter holes produced by Direct Metal Laser Sintering
    • Mariusz Deja
    • Dawid Zieliński
    2020 Pełny tekst RAPID PROTOTYPING JOURNAL

    Purpose The purpose of this research is to evaluate the geometric quality of small diameter holes in parts printed by DMLS technology. An in-process optical inspection method is proposed and assessed during a pilot study. The influence of the theoretical hole diameter assumed in a CAD system and the sample thickness (hole length) on the hole clearance was analysed. Design/methodology/approach The samples made of two different materials: EOS MaragingSteel MS1 and aluminium alloy EOS Aluminium consisted of straight through holes of different diameters and lengths. Dimensional and shape accuracy of the holes were determined with the use of the image processing software and the computer analysis of 2-D images. The definition of the equivalent hole diameter was proposed to calculate the hole clearance. Feret’s diameters were determined for the evaluation of the shape accuracy. Findings The dependency between the equivalent hole diameter and the theoretical diameter was approximated by the linear function for a specific sample thickness. Additionally, a general empirical model for determining the hole clearance was developed, allowing for calculating the equivalent hole diameter as a function of a sample thickness and a theoretical hole diameter. Practical implications Developed functions can be used by designers for a proper assignment of a hole diameter to achieve the required patency. The relevant procedures and macros based on proposed empirical models can be embedded in CAD systems to support the designing process. Originality/value The analysis of the geometric quality of the holes in parts printed by DMLS was based on the computer analysis of 2-D images. The proposed method of assessing the shape accuracy of straight through holes is relatively cheap, is widely available and can be applied to the features of other shapes produced by 3D printing.

  • A Population-Based Method with Selection of a Search Operator
    • Krystian Łapa
    • Krzysztof Cpałka
    • Tacjana Niksa-Rynkiewicz
    • Wang Lipo
    2020

    This paper presents a method based on a population in which the parameters of individuals can be processed by operators from various population-based algorithms. The mechanism of selecting operators is based on the introduction of an additional binary parameters vector located in each individual, on the basis of which it is decided which operators are to be used to modify individuals’ parameters. Thus, in the proposed approach, many operators can be used simultaneously for this purpose. As part of the paper various methods of initializing binary parameters, various population sizes, and their impact on the operation of the algorithm were tested. The simulation was carried out on a wellknown set of benchmark functions.

  • A pore-scale thermo–hydro-mechanical model for particulate systems
    • Robert Caulk
    • Luc Sholtès
    • Marek Krzaczek
    • Bruno Chareyre
    2020 COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING

    A pore scale numerical method dedicated to the simulation of heat transfer and associated thermo–hydro-mechanical couplings in granular media is described. The proposed thermo–hydro-mechanical approach builds on an existing hydromechanical model that employs the discrete element method for simulating the mechanical behavior of dense sphere packings and combines it with the finite volume method for simulating pore space fluid flow and the resulting hydro-mechanical coupling. Within the hydro-mechanical framework, the pore space is discretized as a tetrahedral network whose geometry is defined by the triangulation of discrete element method (DEM) particle centers. It is this discretization of DEM particle contacts and tetrahedral pore spaces that enables the efficient conductive and advective heat transfer models proposed herein. In particular, conductive heat transfer is modeled explicitly between and within solid and fluid phases: across DEM particle contacts, between adjacent tetrahedral pores, and between pores and incident particles. Meanwhile, advective heat transfer is added to the existing implicit fluid flow scheme by estimating mass–energy–flux from pressure induced fluid fluxes. In addition to the heat transfer model, a thermo-mechanical coupling is implemented by considering volume changes based on the thermal expansion of particles and fluid. The conduction and advection models are verified by presenting comparisons to an analytical solution for conduction and a fully resolved numerical solution for conduction and advection. Finally, the relevance of the fully coupled thermo–hydro-mechanical model is illustrated by simulating an experiment where a saturated porous rock sample is subjected to a cyclic temperature loading.

  • A Power-Efficient Digital Technique for Gain and Offset Correction in Slope ADCs
    • Miron Kłosowski
    2020 Pełny tekst IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS

    In this brief, a power-efficient digital technique for gain and offset correction in slope analog-to-digital converters (ADCs) has been proposed. The technique is especially useful for imaging arrays with massively parallel image acquisition where simultaneous compensation of dark signal non-uniformity (DSNU) as well as photo-response non-uniformity (PRNU) is critical. The presented approach is based on stopping the ADC clock by a specially prepared clock-enable pulse sequence. This brief describes the properties of ADCs utilizing this clock stopping technique, including power dissipation, integral, and differential nonlinearity. The experimental validation has been performed for the ASIC implementation of the 128-pixel imager containing photo-sensors integrated with ADCs. Finally, a modification is proposed that increases the accuracy of the gain correction. Measurements confirm functionality of the proposed approach. Reduction of the PRNU (to ~0.4 LSB) has been achieved as well.

  • A Preliminary Study and Analysis of Tidal Stream Generators
    • Saad bin Abul Kashem
    • Molla E. Majid
    • Mujahid Tabassum
    • Azad Ashraf
    • Jarosław Guziński
    • Krzysztof Łuksza
    2020 Pełny tekst Acta Energetica

    For a sustainable future, tidal energy can play a vital role. Tidal energy relies on the gravitational pull of the Moon and the Sun along with the centrifugal forces created by the Earth. Tidal barrage uses the potential energy from the tide and has been very successful in electricity production. With the help of a turbine, kinetic energy can also be harnessed from tidal currents to generate electricity. However, it is not economically feasible to use this type of technology for large scale production of electrical energy. It is important to note that the development of this technology is still in the early stage. This research paper provides a preliminary discussion of tidal energy generation using a few different technologies. Initial research has been done using Computational Fluid Dynamics and SolidWorks software on the tidal stream generator and tidal barrage system. Some of the key challenges are also identified in terms of the development of the tidal energy conversion system.

  • A Proposed Machine Learning Model for Forecasting Impact of Traffic-Induced Vibrations on Buildings
    • Anna Jakubczyk-Gałczyńska
    • Robert Jankowski
    2020

    Traffic-induced vibrations may cause various damages to buildings located near the road, including cracking of plaster, cracks in load-bearing elements or even collapse of the whole structure. Measurements of vibrations of real buildings are costly and laborious. Therefore the aim of the research is to propose the original numerical algorithm which allows us to predict, with high probability, the nega-tive dynamic impact of traffic-induced vibrations on the examined building. The model has been based on machine learning. Firstly, the experimental tests have been conducted on different buildings using specialized equipment taking into ac-count six factors: distance from the building to the edge of the road, type of sur-face, condition of road surface, condition of the building, the absorption of soil and the type of vehicle. Then, the numerical algorithm based on machine learning (using support vector machine) has been created. The results of the conducted analysis clearly show that the method can be considered as a good tool for pre-dicting the impact of traffic-induced vibrations on buildings, being characterized by high reliability.

  • A Proposed Soft Computing Model for Ultimate Strength Estimation of FRP-Confined Concrete Cylinders
    • Reza Kamgar
    • Hosein Naderpour
    • Houman Ebrahimpour Komeleh
    • Anna Jakubczyk-Gałczyńska
    • Robert Jankowski
    2020 Pełny tekst Applied Sciences-Basel

    In this paper, the feed-forward backpropagation neural network (FFBPNN) is used to propose a new formulation for predicting the compressive strength of fiber-reinforced polymer (FRP)-confined concrete cylinders. A set of experimental data has been considered in the analysis. The data include information about the dimensions of the concrete cylinders (diameter, length) and the total thickness of FRP layers, unconfined ultimate concrete strength, ultimate confinement pressure, ultimate tensile strength of the FRP laminates and the ultimate concrete strength of the concrete cylinders. The confined ultimate concrete strength is considered as the output data, while other parameters are considered as the input data. These parameters are mostly used in existing FRP-confined concrete models. Soft computing techniques are used to estimate the compressive strength of FRP-confined concrete cylinders. Finally, a new formulation is proposed. The results of the proposed formula are compared to the existing methods. To verify the proposed method, results are compared with other methods. The results show that the described method can forecast the compressive strength of FRP-confined concrete cylinders with high precision in comparison with the existing formulas. Moreover, the mean percentage of error for the proposed method is very low (3.49%). Furthermore, the proposed formula can estimate the ultimate compressive capacity of FRP-confined concrete cylinders with a different type of FRP and arbitrary thickness in the initial design of practical projects.

  • A Rapid and Simple Method for Screening Microorganisms with a Potential for Catechol Biodegradation
    • Natalia Filipowicz
    • Hubert Cieśliński
    2020 International Journal of Environmental Research

    Catechol is a highly toxic compound that is also a key intermediate in biodegradation pathways of various aromatic compounds. In this paper, a new screening method for isolation of microorganisms with the potential for catechol biodegradation is reported. The method described is based on the ability of catechol to form a color complex with Fe3+ ions. For this purpose, basal medium that is widely used for classification of microorganisms by carbon requirements was used. Specifically, minimal Bushnell Haas medium plates supplemented with catechol at 500 mg l−1 concentration were used for both yeast and bacteria cultivation. After appearance of microorganism colonies on the growth medium, each plate was flooded with 7.0 ml of 5% (w/v) of FeCl3 and incubated for a period of 5 min at room temperature. Flooding with this solution led to the formation of a green color from Fe3+-catechol complexes in the growth medium and an appearance of clear zones around colonies of microorganisms that utilize catechol as a sole source of carbon. Based on this, the presented method could be useful as a screening step for microorganisms with a potential for catechol biodegradation.

  • A rapid dispersive liquid–liquid microextraction of antimicrobial onion organosulfur compounds in animal feed coupled to gas chromatography-mass spectrometry
    • Marta Pastor-belda
    • Natalia Arroyo-manzanares
    • Kateryna Yavir
    • Paloma Abad
    • Natalia Campillo
    • Manuel Hernandez-Cordoba
    • Pilar Vinas
    2020 Analytical Methods

    A rapid analytical procedure is proposed for determining two antimicrobial onion organosulfur compounds, propyl disulfide (PDS) and propyl propane thiosulfonate (PTSO), in animal feed. The use of PTSO as a natural ingredient in animal feed is allowed due to its antimicrobial activity against pathogenic organisms. Two analytical methodologies using gas chromatography coupled to mass spectrometry (GC-MS) are compared. After the extraction of the compounds from animal feed with acetonitrile, dispersive solid phase extraction (DSPE) as a cleaning stage with C18, or dispersive liquid–liquid microextraction (DLLME), using 100 mL of CHCl3, was tried. Both the methods were validated using a pig feed sample and the best results were achieved by DLLME. This technique provided cleaner extracts, five-times greater linear ranges and lower detection limits than simple cleaning due to the enrichment factor achieved. The relative standard deviation decreased from 22% with DSPE to 13% with DLLME. The usefulness of the DLLME-GC-MS methodology was tested by analysing 10 different samples of chicken, calf, hen, cow and fish feed. The concentrations of PDS were in the 0.1–1.7 mg g1 range and those of PTSO were between 0.09 and 2.1 mg g-1

  • A reactive algorithm for deducing nodal forwarding behavior in a multihop ad-hoc wireless network in the presence of errors
    • Karol Rydzewski
    • Jerzy Konorski
    2020 Pełny tekst International Journal of Electronics and Telecommunications

    A novel algorithm is presented to deduce individual nodal forwarding behavior from standard end-to-end acknowledgments. The algorithm is based on a well-established mathematical method and is robust to network related errors and nodal behavior changes. The proposed solution was verified in a network simulation, during which it achieved sound results in a challenging multihop ad-hoc network environment.

  • A Review of Emotion Recognition Methods Based on Data Acquired via Smartphone Sensors
    • Agata Kołakowska
    • Wioleta Szwoch
    • Mariusz Szwoch
    2020 Pełny tekst SENSORS

    In recent years, emotion recognition algorithms have achieved high efficiency, allowing the development of various affective and affect-aware applications. This advancement has taken place mainly in the environment of personal computers offering the appropriate hardware and sufficient power to process complex data from video, audio, and other channels. However, the increase in computing and communication capabilities of smartphones, the variety of their built-in sensors, as well as the availability of cloud computing services have made them an environment in which the task of recognising emotions can be performed at least as effectively. This is possible and particularly important due to the fact that smartphones and other mobile devices have become the main computer devices used by most people. This article provides a systematic overview of publications from the last 10 years related to emotion recognition methods using smartphone sensors. The characteristics of the most important sensors in this respect are presented, and the methods applied to extract informative features on the basis of data read from these input channels. Then, various machine learning approaches implemented to recognise emotional states are described.

  • A screening of select toxic and essential elements and persistent organic pollutants in the fur of Svalbard reindeer
    • Aneta Pacyna-Kuchta
    • Paulina Wietrzyk-Pełka
    • Michał Węgrzyn
    • Marcin Frankowski
    • Żaneta Polkowska
    2020 Pełny tekst CHEMOSPHERE

    Reindeers play an important role in the polar ecosystem, being long-lived sole vegetarians feeding on local vegetation. They can be used as a valuable bioindicator, helping us to understand contaminants’ impact on the polar terrestrial ecosystem. Still, scarce data exist from research in which polar herbivores (especially those from the European parts of the Arctic) were a major study subject for trace elements and persistent organic pollutant determination. Here, Svalbard reindeer fur has been used to determine metals, non-metals and metalloids using ICP-MS, and several persistent organic pollutants including polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) using gas chromatography coupled to a tandem mass spectrometer (GC-MS/MS). Samples were collected from reindeer populations living in the area near Ny-Ålesund and Longyearbyen. Essential elements like Fe, Mg, Zn, K, Ca, Cu predominated in the trace elements profile. Median values of As, Cd, Co, Li, Ni, Se and V were all below 0.5 mg/g dw. Mercury was below detection limit in all samples, while the Pb median varied from 0.35 to 0.74 mg/g dw. Except acenaphthylene and fluorene, PAHs were detectable only in samples collected in the vicinity of Longyearbyen. Of 15 studied pesticides, only DDT and its metabolites were above the detection limit, and, of PCBs, only PCB28.

  • A shear stress micromodel of urinary tract infection by the Escherichia coli producing Dr adhesin
    • Beata Zalewska-Piątek
    • Marcin Olszewski
    • Tomasz Lipniacki
    • Sławomir Błoński
    • Miłosz Wieczór
    • Piotr Bruździak
    • Anna Skwarska
    • Bogdan Nowicki
    • Stella Nowicki
    • Rafał Piątek
    2020 Pełny tekst PLoS Pathogens

    In this study, we established a dynamic micromodel of urinary tract infection to analyze the impact of UT-segment-specific urinary outflow on the persistence of E. coli colonization. We found that the adherence of Dr+ E. coli to bladder T24 transitional cells and type IV collagen is maximal at lowest shear stress and is reduced by any increase in flow velocity. The analyzed adherence was effective in the whole spectrum of physiological shear stress and was almost irreversible over the entire range of generated shear force. Once Dr+ E. coli bound to host cells or collagen, they did not detach even in the presence of elevated shear stress or of chloramphenicol, a competitive inhibitor of binding. Investigating the role of epithelial surface architecture, we showed that the presence of budding cells–a model microarchitectural obstacle–promotes colonization of the urinary tract by E. coli. We report a previously undescribed phenomenon of epithelial cell “rolling-shedding” colonization, in which the detached epithelial cells reattach to the underlying cell line through a layer of adherent Dr+ E. coli. This rolling-shedding colonization progressed continuously due to “refilling” induced by the flow-perturbing obstacle. The shear stress of fluid containing free-floating bacteria fueled the rolling, while providing an uninterrupted supply of new bacteria to be trapped by the rolling cell. The progressive rolling allows for transfer of briefly attached bacteria onto the underlying monolayer in a repeating cascading event.

  • A simple model of the trap-assisted recombination with the excitonic Auger mechanism
    • Jędrzej Szmytkowski
    2020 Pełny tekst European Physical Journal Plus

    We present a simple model of the trap-assisted recombination combined with the excitonic Auger mechanism. It has been shown that only six independent transitions of electrons and holes should be taken into account to describe a combination of the Shockley–Read–Hall (SRH) recombination with this excitonic process. This is in opposition to a well-known model of the SRH mechanism with the free carriers Auger effect via deep states, where eight separated transitions take place. The derived equation for the effective recombination rate can be useful for modeling the excitonic processes in semiconductors, especially in photovoltaic and optoelectronic devices.

  • A space-efficient algorithm for computing the minimum cycle mean in a directed graph
    • Paweł Pilarczyk
    2020 Journal of Mathematics and Computer Science-JMCS

    An algorithm is introduced for computing the minimum cycle mean in a strongly connected directed graph with n vertices and m arcs that requires O(n) working space. This is a considerable improvement for sparse graphs in comparison to the classical algorithms that require O(n^2) working space. The time complexity of the algorithm is still O(nm). An implementation in C++ is made publicly available at http://www.pawelpilarczyk.com/cymealg/.

  • A strong preference for the TA/TA dinucleotide step discovered for an acridine-based, potent antitumor dsDNA intercalator, C-1305: NMR-driven structural and sequence-specificity studies
    • Tomasz Laskowski
    • Witold Andrałojć
    • Jakub Grynda
    • Paulina Gwarda
    • Jan Mazerski
    • Zofia Gdaniec
    2020 Pełny tekst Scientific Reports

    Triazoloacridinone C-1305, a potent antitumor agent recommended for Phase I clinical trials, exhibits high activity towards a wide range of experimental colon carcinomas, in many cases associated with complete tumor regression. C-1305 is a well-established dsDNA intercalator, yet no information on its mode of binding into DNA is available to date. Herein, we present the NMR-driven and MD-refined reconstruction of the 3D structures of the d(CGATATCG)2:C-1305 and d(CCCTAGGG)2:C-1305 non-covalent adducts. In both cases, the ligand intercalates at the TA/TA site, forming well-defined dsDNA:drug 1:1 mol/mol complexes. Orientation of the ligand within the binding site was unambiguously established by the DNA/ligand proton-proton NOE contacts. A subsequent, NMR-driven study of the sequence-specificity of C-1305 using a series of DNA duplexes, allowed us to confirm a strong preference towards TA/TA dinucleotide steps, followed by the TG/CA steps. Interestingly, no interaction at all was observed with duplexes containing exclusively the AT/AT, GG/CC and GA/TC steps.

  • A Study of Cross-Linguistic Speech Emotion Recognition Based on 2D Feature Spaces
    • Gintautas Tamulevicius
    • Grazina Korvel
    • Anil Bora Yayak
    • Povilas Treigys
    • Jolita Bernataviciene
    • Bożena Kostek
    2020 Pełny tekst Electronics

    In this research, a study of cross-linguistic speech emotion recognition is performed. For this purpose, emotional data of different languages (English, Lithuanian, German, Spanish, Serbian, and Polish) are collected, resulting in a cross-linguistic speech emotion dataset with the size of more than 10.000 emotional utterances. Despite the bi-modal character of the databases gathered, our focus is on the acoustic representation only. The assumption is that the speech audio signal carries sufficient emotional information to detect and retrieve it. Several two-dimensional acoustic feature spaces, such as cochleagrams, spectrograms, mel-cepstrograms, and fractal dimension-based space, are employed as the representations of speech emotional features. A convolutional neural network (CNN) is used as a classifier. The results show the superiority of cochleagrams over other feature spaces utilized. In the CNN-based speaker-independent cross-linguistic speech emotion recognition (SER) experiment, the accuracy of over 90% is achieved, which is close to the monolingual case of SER.

  • A study of the kinetics of bismuth telluride synthesis by an oxide reduction method
    • Bartosz Jakub Trawiński
    • Beata Bochentyn
    • Marcin Stanisław Łapiński
    • Bogusław Kusz
    2020 Pełny tekst THERMOCHIMICA ACTA

    The kinetics of a reduction of bismuth and tellurium oxides in a hydrogen atmosphere, leading to the formation of thermoelectric bismuth telluride is investigated. The evaluation of the reaction kinetics was based on a thermogravimetric analysis performed in non-isothermal conditions. A non-parametric analysis method and the Friedman method were used for the evaluation of the data. Additionally, for a better understanding of the process, reactions of the reduction of Bi2O3, TeO2 as well as Bi2Te2O7 and Bi2Te4O11, which are formed as intermediate products, were investigated. The activation energies calculated for the reactions were between 56 kJ/mol in the case of the Bi2Te2O7 reduction and 100 kJ/mol for the reduction of mixed oxides. No correlation between the activation energy and the Bi:Te ratio in the reduced material was found. The calculated conversion functions also differed between the investigated reactions. A self-heating process was found for TeO2 and Bi2Te4O11 reduction reactions. In the case of the tellurium oxide, it was assigned to the melting of Te nanoparticles. These effects were also found to enhance the synthesis of Bi2Te3 by the reduction of mixed bismuth and tellurium oxides. The resulting thermoelectric material was found to be completely reduced, with no traces of oxygen in the XPS spectrum. EDX mapping of the cross-section of material’s grains revealed a homogenous distribution of elements in the final product.

  • A study on fibre-reinforced concrete elements properties based on the case of habitat modules in the underwater sills
    • Marzena Kurpińska
    • Beata Grzyl
    • Adam Kristowski
    2020 Pełny tekst Polish Maritime Research

    Hydrotechnical constructions are mostly objects functioning in extreme conditions and requiring a custom-made construction project. In the case of using prefabricated elements, it is required to develop production, transport, assembly, conservation and repair technology. Concerning the problem of concrete cracks, modern repair systems allow positive effects to be achieved in many cases of concrete elements repair. In this work an attempt has been made to assess the properties of concrete, situated in the Baltic Sea environment, in which traditional rebar was partly replaced by dispersed fibre-phase. Fibre-reinforced concrete belongs to the group of composite materials. The presence of fibres helps to increase the tensile strength, flexural strength and resilience and also prevents the appearance of cracks. In the given paper we will also discuss basic parameters of steel and polymer fibres and the influence of both types of fibres on the maturing and hardened concrete. In this work special attention has been paid to the advantages of polypropylene and polymer fibres with regard to commonly-known steel fibres. The use of synthetic fibres will be advantageous in constructions where the reduction of shrinkage cracks and high resilience are essential. On top of that, the use of synthetic fibres is highly recommended when constructing objects that will be exposed to the impact of an aggressive environment. Undoubtedly, polymer fibres are resistant to the majority of corrosive environments. Fibre-reinforced concretes are a frequently implemented construction solution. The possibility of concrete modification allows the emergence of new construction materials with improved physical-mechanical properties, under the condition of being applied relevantly.

  • A Subspace-Splitting Moment-Matching Model-Order Reduction Technique for Fast Wideband FEM Simulations of Microwave Structures
    • Damian Szypulski
    • Grzegorz Fotyga
    • Valentin de la Rubia
    • Michał Mrozowski
    2020 Pełny tekst IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES

    This article describes a novel model-order reduction (MOR) approach for efficient wide frequency band finite-element method (FEM) simulations of microwave components. It relies on the splitting of the system transfer function into two components: a singular one that accounts for the in-band system poles and a regular part that has no in-band poles. In order to perform this splitting during the reduction process, the projection basis is formed of two sets of orthogonal vectors that must be computed in sequence. The first set to be computed consists of the in-band eigenvectors that are associated with the dynamics of the electromagnetic field, while the second set uses the block moments of the original system, which are computed in the orthogonal complement to the subspace spanned by the in-band eigenvectors. The advantage of this method is that it results in a more compact reduced-order model than a method that employs only moment matching for the projection basis computations.

  • A survey of neural networks usage for intrusion detection systems
    • Anna Drewek-Ossowicka
    • Mariusz Pietrołaj
    • Jacek Rumiński
    2020 Pełny tekst Journal of Ambient Intelligence and Humanized Computing

    In recent years, advancements in the field of the artificial intelligence (AI) gained a huge momentum due to the worldwide appliance of this technology by the industry. One of the crucial areas of AI are neural networks (NN), which enable commer‐ cial utilization of functionalities previously not accessible by usage of computers. Intrusion detection system (IDS) presents one of the domains in which neural networks are widely tested for improving overall computer network security and data privacy. This article gives a thorough overview of recent literature regarding neural networks usage in intrusion detection system area, including surveys and new method proposals. Short tutorial descriptions of neural network architectures, intrusion detection system types and training datasets are also provided.

  • A Theoretical and Experimental Study of Moderate Temperature Alfa Type Stirling Engines
    • Jacek Kropiwnicki
    • Mariusz Furmanek
    2020 Pełny tekst ENERGIES

    The Stirling engine is a device that allows conversion of thermal energy into mechanical energy with relatively high efficiency. Existing commercial designs are mainly based on the usage of high temperature heat sources, whose availability from renewable or waste heat sources is significantly lower than that of moderate temperature sources. The paper presents the results of experimental research on a prototype alpha type Stirling engine powered by a moderate temperature source of heat. Obtained results enabled calibration of the evaluated theoretical model of the Stirling engine. The model of the engine has been subsequently used for the analysis of regenerator effectiveness influenced by the charge pressure and the heating temperature. Performed study allowed to determine further development directions of the prototype engine to improve its power and efficiency. As a result of optimization, worked out design will potentially increase the indicated efficiency up to 19.5% (5.5% prototype) and the indicated power up to 369 W (114 W prototype).