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  • Estimating the parameter of inequality aversion on the basis of a parametric distribution of incomes
    • Stanisław Kot
    2020 Pełny tekst EQUILIBRIUM Quarterly Journal of Economics and Economic Policy

    Research background: In applied welfare economics, the constant relative inequality aversion function is routinely used as the model of a social decisionmaker’s or a society’s preferences over income distributions. This function is entirely determined by the parameter, ε, of inequality aversion. However, there is no authoritative answer to the question of what the range of ε an analyst should select for empirical work. Purpose of the article: The aim of this paper is elaborating the method of deriving ε from a parametric distribution of disposable incomes. Methods: We assume that households’ disposable incomes obey the generalised beta distribution of the second kind GB2(a,b,p,q). We have proved that, under this assumption, the social welfare function exists if and only if ε belongs to (0,ap+1) interval. The midpoint εmid of this interval specifies the inequality aversion of the median social-decisionmaker. Findings & Value added: The maximum likelihood estimator of εmid has been developed. Inequality aversion for Poland 1998–2015 has been estimated. If inequality is calculated on the basis of disposable incomes, the standard inequality–development relationship might be complemented by inequality aversion. The “augmented” inequality–development relationship reveals new phenomena; for instance, the stage of economic development might matter when assessing the impact of inequality aversion on income inequality.

  • Estimating the uncertainty of discharge coefficient predicted for oblique side weir using Monte Carlo method
    • Ahmed Y. Mohammed
    • Anna Golijanek-Jędrzejczyk
    2020 Pełny tekst FLOW MEASUREMENT AND INSTRUMENTATION

    Side weir is a hydraulic structure, which is used in irrigation systems to divert some water from main to side channel. It is installed at the entrance of the side channel to control and measure passing water into the side channel. Many studies provided side weir water surface profile and coefficient of discharge to measure water discharge diverted into the side channel. These studies dealt with different side weir shapes (rectangular, trapezoidal, triangular and circular), which were installed perpendicular to the flow direction. Recently, some studies dealt with skew side weir, but these studies still need to more investigation. Here we report to investigate oblique side weir theoretically using statistical method to supported other studies in this case. Measurement uncertainty discharge coefficient Cd was obtained by two methods: analytical according to the 'Guide to the expression of uncertainty in measurement' and the Monte Carlo method. The results indicate that all experimental results are consistent with the analytical results. The relative expanded uncertainty of the discharge coefficient Cd does not exceed 2%.

  • Estimation and Prediction of Vertical Deformations of Random Surfaces, Applying the Total Least Squares Collocation Method
    • Zbigniew Wiśniewski
    • Waldemar Kamiński
    2020 Pełny tekst SENSORS

    This paper proposes a method for determining the vertical deformations treated as random fields. It is assumed that the monitored surfaces are subject not only to deterministic deformations, but also to random fluctuations. Furthermore, the existence of random noise coming from surface’s vibrations is also assumed. Such noise disturbs the deformation’s functional models. Surface monitoring with the use of the geodetic levelling network of a free control network class is carried out. Assuming that, in some cases, the control networks are insufficient in surface’s deformation analysis, additional and non–measurable reference points have been provided. The prediction of these points’ displacements and estimation of the free control network points’ displacement are carried out using the collocation method applying the total least squares adjustment. The proposed theoretical solutions were verified by the simulation methods and on the example of a real control network

  • Estimation of Broadband Complex Permeability Using SIW Cavity-Based Multimodal Approach
    • Nilesh K. Tiwari
    • Abhishek Jha
    • Surya P. Singh
    • M. Jaleel Akhtar
    2020 Pełny tekst IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT

    In this article, an attractive multimodal substrate integrated waveguide (SIW) based methodology is presented for the characterization of magnetic materials in the broadband microwave frequency. The proposed approach employs a modified feed under-coupled SIW cavity instead of conventional feed over-coupled multiple SIW cavities; it uses the modified closedform expression, developed from the first principle to consider the effect of finite sample dimensions, and mode-specific sinusoidal field variations, which were not considered before for magnetic testing using the over-coupled SIW cavity and conventional formulations. The metallic cavity borne approximations i.e., very small frequency shift for the imaginary part calculation, and very high Q-factor for the real permeability estimation are also relaxed in the modified formulations. The proposed technique is numerically verified using the full-wave electromagnetic (EM) simulator for several dispersive and nondispersive standard samples; thereafter, it is validated for the estimation of complex permeability of synthesized dispersive magnetic composites. It can characterize the dispersive magnetic composites, where the permeability value varies from paramagnetic to diamagnetic range, with improved accuracy than that of the conventional cavity perturbation approach. The modified formulation provides 34% and 12% better estimation of loss tangent and real permeability, respectively, as compared with the conventional technique. The uncertainty analysis for change in sample volume, sample misalignment, and the possible air gap is also carried out in detail. The proposed scheme typically provides more than 92% and 84% accuracy in the measured values of real permeability and loss tangent data, respectively, for various synthesized magnetic samples in broadband of microwave frequency (10–22 GHz).

  • Etapy projektowania statków oraz przepływ dokumentacji
    • Dominik Kreft
    2020 Pełny tekst Journal of Polish CIMEEAC

    W artykule przedstawiono główne etapy projektu okrętowego wg. różnych autorów. Następnie opisano zakres prac dla każdego z etapów i przedstawiono je w postaci spirali projektowej. Przedstawiono i opisano również schemat przepływu dokumentacji podczas realizacji projektu klasyfikacyjnego z wyszczególnieniem armatora, biura projektowego, stoczni oraz towarzystwa klasyfikacyjnego.

  • Evaluating calibration and robustness of pedestrian detectors
    • Sebastian Cygert
    • Andrzej Czyżewski
    2020

    In this work robustness and calibration of modern pedestrian detectors are evaluated. Pedestrian detection is a crucial perception com- ponent in autonomous driving and here we study its performance under different image corruptions. Furthermore, we provide analysis of classifi- cation calibration of pedestrian detectors and we show a positive effect of using style-transfer augmentation technique. Our analysis is aimed as a step towards understanding and improving current safety-critical detection systems.

  • Evaluating the Cost of Personnel Activities in Cybersecurity Management: A Case Study
    • Rafał Leszczyna
    2020 Pełny tekst

    The methods of cybersecurity costs' evaluation are inclined towards the cost of incidents or technological acquirements. At the same time, there are other, less visible costs related to cybersecurity that require proper recognition. These costs are associated with the actions and the time spent by employees on activities connected to cybersecurity management. The costs form a considerable component of cybersecurity expenditures, but because they become evident only during scrupulous analyses, often they are disregarded. CAsPeA is a method that enables estimating the costs based on a model derived from the Activity-Based Costing (ABC) and the NIST SP 800-53 guidelines. This paper presents the application of CAsPeA in a steel structures manufacturing company.

  • Evaluation of a company’s image on social media using the Net Sentiment Rate
    • Anna Baj-Rogowska
    2020

    Vast amounts of new types of data are constantly being created as a result of dynamic digitization in all areas of our lives. One of the most important and valuable categories for business is data from social networks such as Facebook. Feedback resulting from the sharing of thoughts and emotions, expressed in comments on various products and services, is becoming the key factor on which modern business is based. This feedback is called sentiment on social media. The sentiment analysis method is used for the mining of polarity views, feelings and emotions from text data with the help of natural language processing (NLP). The fundamental task in this technique is to classify the polarity of opinions into classes such as positive, negative and neutral. This chapter introduces a novel approach to the quantitative measurement of sentiment by means of a created indicator called the Net Sentiment Rate (NSR). The proposed NSR expresses the net sentiment extracted from text data and provides values on a scale from -1 to +1. The Net Sentiment Rate implementation has been verified on large datasets crawled from Facebook in the period from 1 October 2014 to 31 December 2018, for three international companies from the same sector. The created Net Sentiment Rate, together with the classification of its strength, and its verification, constitutes the contribution of this study.

  • Evaluation of Foundation Input Motions Based on Kinematic Interaction Models
    • Tomasz Falborski
    2020

    The present study was designed to demonstrate the importance of baseslab averaging and embedment effects on the foundation-level input motions due to earthquake excitations. Evaluation of foundation-level input motions based on the most commonly adopted kinematic interaction models are presented. In order to conduct this investigation, original records of horizontal accelerations for two casestudy buildings were utilized. Computed foundation-level input motions, in both NS and EW directions, were compared to the actual acceleration-time histories recorded at the foundation levels. The results clearly indicate that incorporating base-slab averaging and embedment effects in seismic analyses can modify the dynamic excitation imposed at the foundation level, and, as a consequence, lead to more accurate structural response due to earthquake ground motions.

  • Evaluation of Immobilization of Selected Peat-Isolated Yeast Strains of the Species Candida albicans and Candida subhashii on the Surface of Artificial Support Materials Used for Biotrickling Filtration
    • Milena Marycz
    • Anna Brillowska-Dąbrowska
    • Jacek Gębicki
    2020 Pełny tekst Processes

    The paper describes the process of n-butanol abatement by unicellular fungi, able to deplete n-butanol content in gas, by using n-butanol as source of carbon. Isolated and identified fungi species Candida albicans and Candida subhashii were subjected to a viability process via assimilation of carbon from hydrophilic and hydrophobic compounds. The isolates, which exhibited the ability to assimilate carbon, were immobilized on four different types of artificial support materials used for biotrickling filtration. Application of optical microscopy, flow cytometry and the tests employing propidium iodide and annexin V revealed viability of the fungi isolated on support materials’ surfaces at the average level of 95%. The proposed method of immobilization and its evaluation appeared to be effective, cheap and fast. Based on performed comparative analyses, it was shown that polyurethane foam and Bialecki rings (25 × 25) could be attractive support materials in biotrickling filtration.

  • Evaluation of Lombard Speech Models in the Context of Speech in Noise Enhancement
    • Grazina Korvel
    • Krzysztof Kąkol
    • Olga Kurasova
    • Bożena Kostek
    2020 Pełny tekst IEEE Access

    The Lombard effect is one of the most well-known effects of noise on speech production. Speech with the Lombard effect is more easily recognizable in noisy environments than normal natural speech. Our previous investigations showed that speech synthesis models might retain Lombard-effect characteristics. In this study, we investigate several speech models, such as harmonic, source-filter, and sinusoidal, applied to Lombard speech in the context of speech enhancement. For this purpose, 100 utterances of natural speech, and 100 with the Lombard effect induced are used. The goal of this study is to check to what extent speech utterances based on these models are recognizable and at what SNR (Signal-to-Noise Ratio) level threshold a particular model stops working. For this purpose, the synthesized models and Lombard speech are mixed with babble speech and street noise recordings with different SNRs. The quality of these models is measured, employing objective indicators as well as subjective tests. Since there is no standardized measure to apply to enhanced speech, an objective measure of assessing the speech quality of a model synthesizing Lombard speech characteristics, based on a feature vector, is proposed. Our approach is then compared with the standardized metric used in telecommunications as well as with subjective test results. The experimental investigations show the superiority of the source-filter models applied to synthesize Lombard speech over other models utilized. Also, the measure proposed correlates more closely with the results of the subjective evaluation than the outcomes from the ITU-T P.563 recommendation. This was checked with a ANOVA statistical analysis.

  • Evaluation of Mechanical Properties of Two-Stage Concrete and Conventional Concrete Using Nondestructive Tests
    • Ali M. Rajabi
    • Farzam Omidimoaf
    • Hakim Abdelgader
    2020 Pełny tekst JOURNAL OF MATERIALS IN CIVIL ENGINEERING

    Different types of concrete mixtures are used as building materials. The manufacturing process of two-stage concrete (TSC) differs from that of conventional concrete. This study investigated conventional mechanical properties derive empirical relations for estimation of the mechanical parameters of TSC and conventional concrete mixtures. TSC was used to prepare 216 specimens and conventional concrete was used to prepare 108 specimens that then were aged for 28 days. Uniaxial compression, Brazilian tensile strength, and point load tests were carried out as destructive testing. Schmidt hammer and ultrasonic pulse velocity tests were carried out as nondestructive testing. The data from testing were categorized as regression or test data. Empirical relations were derived between the parameters for the two types of concrete, and these relations were validated. It was concluded that indirect, nondestructive testing of engineering materials, including concrete, considerably increases the speed and decreases the estimation cost of determining the mechanical parameters. This method can be recommended for estimation of these mechanical parameters.

  • Evaluation of Selected UX Techniques by Product Managers - A Preliminary Survey
    • Jakub Miler
    • Margarita Menjega-Schmidt
    2020

    In this paper we present the results of an opinion survey among 28 IT product managers who evaluated the subjective usefulness of 24 selected UX techniques to 6 IT product management tasks derived from ProdBOK®. We selected the UX techniques based on the literature review and 6 interviews with experienced IT product managers. Based on the survey results, we propose our recommendation of useful techniques for 5 of the 6 studied IT product management tasks. Additionally, we report on the overall perceived usefulness of the UX techniques to all affected IT product management tasks.

  • Evaluation of the Greenness of Analytical Procedures
    • Marta Bystrzanowska
    • Jacek Namieśnik
    • Marek Tobiszewski
    2020

    This contributions introduces the need to develop the methods to evaluate analytical procedures in the light of green analytical chemistry. Green chemistry metrics are not applicable in analytical chemistry because they refer to the mass of product and no product with mass is generated during analytical determination. Analytical greenness evaluations are based on scoring - such as NEMI or Eco-scale or comparative analysis as it is in case of multicriteria decision analysis. Important aspect is also the assessment of solvents and reagents that are applied in analytical procedures for their greening. The different environmental, safety and health parameters are included in the assessments of solvents and reagents. The contribution presents the mechanisms of evaluation and numerous examples. Some results of reagents and solvents assessments are also presented to help analysts in selection greener alternatives.

  • Evaluation of the Influence of Farming Practices and Land Use on Groundwater Resources in a Coastal Multi-Aquifer System in Puck Region (Northern Poland)
    • Adam Szymkiewicz
    • Dawid Potrykus
    • Beata Jaworska-Szulc
    • Anna Gumuła-Kawęcka
    • Małgorzata Pruszkowska-Caceres
    • Lidia Dzierzbicka-Głowacka
    2020 Pełny tekst Water

    This study focuses on the modeling of groundwater flow and nitrate transport in a multi-aquifer hydrosystem in northern Poland, adjacent to Puck Bay (Baltic sea). The main goal was to investigate how changes in land use and farming practices may affect groundwater recharge and submarine groundwater discharge (SGD) to the sea and the associated N-NO3 fluxes. An integrated modelling approach has been developed, which couples the SWAT hydrologic model, MODFLOW-NWT groundwater flow model, and MT3DMS transport model. Transient simulations were performed for a 10 y period, assuming 10 different scenarios of land use (farming, grassland, forest) and crop types. Both recharge and SGD showed a distinct pattern of seasonal time variability. In terms of the average flow rates, the effect of varying crop type was more significant than that of land use change, with the minimum recharge and SGD corresponding to winter wheat and the maximum for peas and potatoes. Nitrate loads were strongly affected by both land use and crop type, with minimum values obtained for grassland and maximum values for canola.

  • EVALUATION OF THE NO2CONCENTRATION PREDICTION POSSIBILITYBASED ON STATIC AND DYNAMIC RESPONSES OF TGS SENSORSAT CHANGING HUMIDITY LEVELS
    • Paweł Kalinowski
    • Łukasz Woźniak
    • Grzegorz Jasiński
    • Piotr Jasiński
    2020 Pełny tekst Metrology and Measurement Systems

    The commercially available metal-oxide TGS sensors are widely used in many applications due to thefact that they are inexpensive and considered to be reliable. However, they are partially selective and theirresponses are influenced by various factors,e.g. temperature or humidity level. Therefore, it is importanttodesign a proper analysis system of the sensor responses. In this paper, the results of examinations of eightcommercial TGS sensors combined in an array and measured over a period of a few months for the purposeof prediction of nitrogen dioxide concentration are presented. The measurements were performed at differentrelative humidity levels. PLS regression was employed as a method of quantitative analysis of the obtainedsensor responses. The results of NO2concentration prediction based on static and dynamic responses ofsensors are compared. It is demonstrated that it is possibleto predict the nitrogen dioxide concentrationdespite the influence of humidity

  • Evaluation of the Possibility of Identifying a Complex Polygonal Tram Track Layout Using Multiple Satellite Measurements
    • Andrzej Wilk
    • Cezary Specht
    • Władysław Koc
    • Krzysztof Karwowski
    • Jacek Skibicki
    • Jacek Szmagliński
    • Piotr Chrostowski
    • Pawel S. Dabrowski
    • Mariusz Specht
    • Marek Zienkiewicz
    • Sławomir Judek
    • Marcin Skóra
    • Sławomir Grulkowski
    2020 Pełny tekst SENSORS

    We present the main assumptions about the algorithmization of the analysis of measurement data recorded in mobile satellite measurements. The research team from the Gda´nsk University of Technology and the Maritime University in Gdynia, as part of a research project conducted in cooperation with PKP PLK (Polish Railway Infrastructure Manager), developed algorithms supporting the identification and assessment of track axis layout. This article presents selected issues concerning the identification of a tramway line’s axis system. For this purpose, the supporting algorithm was developed and measurement data recorded using Global Navigation Satellite System (GNSS) techniques was evaluated and analyzed. The discussed algorithm identifies main track directions from multi-device data and repeated position recordings. In order to observe the influence of crucial factors, the investigated route was carefully selected. The chosen tramway track was characterized by its location in various field conditions and a diversified and complex geometric layout. The analysis of the obtained results was focused on the assessment of the signal’s dispersion and repeatability using residuals in relation to the estimated track’s direction. The presented methodology is intended to support railway infrastructure management processes, mainly in planning and maintenance through an effcient inventory of the infrastructure in service.

  • Evaluation of the resistance of steel–concrete adhesive connection in reinforced concrete beams using guided wave propagation
    • Beata Zima
    • Rafał Kędra
    2020 Archives of Civil and Mechanical Engineering

    The development of the nondestructive diagnostic methods is of significant importance in the last decades. A special attention is paid to diagnostics of reinforced concrete structures, which are very popular in the civil engineering field. A possible use of the guided waves in the estimation of the resistance of steel–concrete adhesive connection is studied in the following paper. The relationships relating adhesive connection resistance and wave propagation characteristics (wave velocity and the time of flight) have been derived and experimentally verified during pull-out tests conducted on a number of reinforced concrete beams varying in the debonding area. The pull-out tests were also monitored ultrasonically. On the basis of the results in the form of the time-domain signals, the theoretical load-carrying capacities of the pulled-out bars have been calculated and compared with the exact experimentally determined values. The high agreement of the results obtained proved the correctness of the developed method. Moreover, the signals registered during pull-out tests allowed to observe the changes of the wave velocity induced by the deterioration of the adhesive connection.

  • Evaluation of the significance of the effect of the active cross-sectional area of the inlet air channel on the specific enthalpy of the exhaust gas of a diesel engine using statistics F of the Fisher-Snedecor distribution
    • Patrycja Puzdrowska
    2020 Pełny tekst Combustion Engines

    This paper presents the application of Fisher-Snedecor distribution F statistics to assess the significance of the influence of changes in the active cross-sectional area of the inlet air channel (Adol) flow in a diesel engine on the observed diagnostic parameter determined on the basis of measurements of the quick changing exhaust gas temperature in the outlet channel, which is the specific enthalpy of the exhaust gas stream within one engine operating cycle (hspal). A plan of experimental tests carried out on the laboratory stand of a single-cylinder Farymann Diesel type D10 laboratory engine was presented and the method of determination of F statistics values for the obtained measurement results was characterized. Representative results of calculations were presented and the strength of Adol input parameter influence on the determined diagnostic parameter hspal simplified physical model of the working process of a compression ignition engine as the object of diagnosis was evaluated. It is planned to further develop the experimental research program to determine the significance of the influence of changes in the values of selected parameters of the engine structure on other diagnostic measures determined from the exhaust gas temperature signal, i.e. the mean peak-to-peak value as well as the rate (intensity) of increase and decrease in its value for individual engine cycles.

  • Evidence of mutations conferring resistance to clarithromycin in wastewater and activated sludge
    • Anna Gnida
    • Ewa Felis
    • Aleksandra Ziembińska-Buczyńska
    • Aneta Łuczkiewicz
    • Joanna Surmacz-Górska
    • Krystyna Olańczuk-Neyman
    2020 3 Biotech

    The occurrence of clarithromycin in wastewater samples and of the activated sludge bacteria possibly resistant to this pharmaceutical was the object of the study. Samples of wastewater or activated sludge were taken from a municipal wastewater treatment plant in summer and winter and characterised regarding their clarithromycin concentrations and the presence of nucleic acid fragments (Cla-sequences) known to be responsible for clarithromycin resistance in Helicobacter pylori. The concentrations of clarithromycin in raw wastewater were about 1086-2271 ng/L. Around 50-60% less of the pharmaceutical was found in treated wastewater. The concentrations were much higher in winter samples, as compared to summer samples. The clarithromycin resistance markers in H. pylori were detected by fluorescence in situ hybridisation in activated sludge bacterial cells. Cla-sequences were found in all the detected Proteobacteria, independently of the sampling season. Among nitrifying or phosphate or glycogen accumulating bacteria only Nitrosomonas spp. revealed presence of the clarithromycin sequences.

  • Evolution of Ag nanostructures created from thin films: UV–vis absorption and its theoretical predictions
    • Robert Kozioł
    • Marcin Łapiński
    • Paweł Syty
    • Damian Koszelow
    • Wojciech Sadowski
    • Józef Eugeniusz Sienkiewicz
    • Barbara Kościelska
    2020 Pełny tekst Beilstein Journal of Nanotechnology

    Ag-based plasmonic nanostructures were manufactured by thermal annealing of thin metallic films. Structure and morphology were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). SEM images show that the formation of nanostructures is influenced by the initial layer thickness as well as the temperature and the time of annealing. The Ag 3d and Ag 4d XPS spectra are characteristic of nanostructures. The quality of the nanostructures, in terms of their use as plasmonic platforms, is reflected in the UV–vis absorption spectra. The absorption spectrum is dominated by a maximum in the range of 450–500 nm associated with the plasmon resonance. As the initial layer thickness increases, an additional peak appears around 350 nm, which probably corresponds to the quadrupole resonance. For calculations leading to a better illustration of absorption, scattering and overall absorption of light in Ag nanoparticles, the Mie theory is employed. Absorbance and the distribution of the electromagnetic field around the nanostructures are calculated by finite-difference time-domain (FDTD) simulations. For calculations a novel approach based on modelling the whole sample with a realistic shape of the nanoparticles, instead of full spheres, was used. This led to a very good agreement with the experiment.

  • Evolution of magnetic and transport properties in (Cr1−xMnx)2AlC MAX-phase synthesized by arc melting technique
    • Kirill V. Sobolev
    • Kamil Kolincio
    • Andrey Emelyanov
    • Aleksandra Mielewczyk-Gryń
    • Maria Gazda
    • Marta Roman
    • Anna Pazniak
    • Valeria Rodionova
    2020 JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

    Herein we initiate a comeback to the arc melting technique to produce MAX-phase solid solutions. Bulk samples of (Cr1−xMnx)2AlC MAX-phase with X = 0, 0.025, 0.05 and 0.1 were synthesized and studied by means of X-ray diffractometry, scanning electron microscopy in combination with energy-dispersive X-ray spectroscopy. Samples were established to be homogeneous with an incorporation of Cr7C3, AlCr2 and Al2O3 secondary phases which is slightly increasing with the raise of the dopant concentration. Manganese successfully intermixes in the MAX-phase structure due to the effect of the high-energetic plasma during the melting process. SQUID magnetometry identified the co-existence of ferro- and antiferromagnetic interactions with the latter prevailing in high temperatures and being attributed to the MAX-phase. Magnetic state transitions were observed at approximately 4 K and 5 K for doped samples which was associated with the presence of the marginal amount of ferromagnetic Mn-based secondary phases. The negative component of magnetoresistance was observed in highly doped samples at low temperatures that is likely due to the influence of ferromagnetic secondary phases as well. Transport properties measurement revealed the satisfactory quality of the produced samples.

  • Evolution of the HVDC Link Connecting Offshore Wind Farms to Onshore Power Systems
    • Roland Ryndzionek
    • Łukasz Sienkiewicz
    2020 Pełny tekst ENERGIES

    This paper presents an overview of the DC link development and evolution dedicated to HVDC structure for connecting offshore wind power plants to onshore power systems. The growing demand for the green energy has forced investors in power industry to look for resources further out at sea. Hence, the development of power electronics and industrial engineering has enabled offshore wind farms to be situated further from the shore and in deeper waters. However, their development will require, among other technologies, DC-DC conversion systems. The advantages of HVDC over HVAC technology in relation to transmission distance are given. The different HVDC configurations and topologies of HVDC converters are elucidated. In this context, the HVDC grids are a promising alternative for the expansion of the existing AC grid.

  • EVOLUTIONARY MULTI–OBJECTIVE WEATHER ROUTING OF SAILBOATS
    • Ewa Sobecka
    • Rafał Szłapczyński
    • Marcin Życzkowski
    2020 Pełny tekst Polish Maritime Research

    The paper presents a multi-objective method, which optimises the route of a sailboat. The presented method makes use of an evolutionary multi-objective (EMO) algorithm, which performs the optimisation according to three objective functions: total passage time, a sum of all course alterations made during the voyage and the average angle of heel. The last two of the objective functions reflect the navigator’s and passenger’s comfort, which may decrease with multiple turns or when experiencing an excessive heel angle for a long time. The optimisation process takes into account static bathymetry-related constraints as well as dynamic constraints related to the sailboat’s safety in changing wind and wave conditions. The method makes use of all of the above and finally returns an approximated Pareto set containing non-dominated solutions to the optimisation problem. The developed method has been implemented as a simulation application. The paper includes selected simulation results followed by their discussion.

  • E-Voting System Evaluation Based on the Council of Europe Recommendations: nVotes
    • David Yeregui
    • David Duenas Cid
    • Hector Moretón
    2020 Pełny tekst

    E-voting implantation has been facing important challenges in recent years. Several incidents, together with a lack of evaluation methodologies social and cultural customs hinder a broader application. In this work, the authors aim to contribute to a safer introduction of e-voting tools by applying a practical evaluation framework strongly based on the security requirements issued by the Council of Europe (CoE) in 2017 to nvotes, a system that has been utilized to cast over 2 million votes over the last 6 years. The ultimate goal of the analysis is not to judge from a rigid, “infallible” but to contribute to a gradual and secure implementation of e-voting solutions in the democratic processes. The authors believe it can constitute a useful source of information for election officials, researchers and voters.

  • Exchange-Traded Funds on European Markets: Has Critical Mass been Reached? Implications for Financial Systems.
    • Adam Marszk
    • Ewa Lechman
    2020 Pełny tekst ENTROPY

    Exchange-traded funds (ETFs) are one of the most rapidly expanding categories of financial products in Europe. One of the key yet still unanswered questions is whether European ETF markets have reached the size at which they could affect the financial systems. In our study, we examine 13 European countries during the period 2004–2017 in order to trace whether the share of ETFs in the total assets of investment funds has reached the ‘critical’ level that makes possible their further growth and can be associated with an influence on the financial system. We use a novel methodological approach that identifies the ‘critical mass’ along diffusion trajectories. Our results show that, in 10 countries, the share of ETFs in assets of investment funds increased. Still, in most countries, the share of ETFs did not exceed 1%. Estimates of the diffusion models indicate that the process of growing shares of ETFs was most dynamic and relatively most stable in Switzerland and United Kingdom. Results of the critical mass analysis imply that its achievement may be forecasted exclusively in these two cases. However, even in such cases there is no substantial evidence for a possible significant influence of ETFs on the local financial systems.

  • Excited states of isoxazole molecules studied by electron energy-loss spectroscopy
    • Ireneusz Linert
    • Mariusz Zubek
    2020 Pełny tekst JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA

    Electron energy-loss spectra were measured in isoxazole in the excitation energy range 3.5−10 eV to investigate the valence excited states. Spectra recorded at different scattering conditions enabled the identification of the singlet and triplet states and the determination of their vertical excitation energies. The two lowest energy triplet bands, ππ* 13A' and ππ* 23A' at 4.20 and 5.30 eV, respectively show vibrational progressions. The first triplet state, 15a'π* 13A” that involves excitation from the nitrogen lone-pair orbital is observed at 5.68 eV. The three singlet valence states, ππ* 11A', nNπ* 11A” and ππ* 21A' are observed at 5.96, 6.49 and 6.88 eV, respectively in accord with the absorption measurements. Resonance excitation of the triplet and singlet states was noticed.

  • Exhaled breath analysis by resistive gas sensors
    • Tomasz Chludziński
    • Andrzej Kwiatkowski
    2020 Pełny tekst Metrology and Measurement Systems

    Breath analysis has attracted human beings for centuries. It was one of the simplest methods to detect various diseases by using human smell sense only. Advances in technology enable to use more reliable and standardized methods, based on different gas sensing systems. Breath analysis requires the detection of volatile organic compounds (VOCs) of the concentrations below individual ppm (parts per million). Therefore, advanced detection methods have been proposed. Some of these methods use expensive and bulky equipment (e.g. optical sensors, mass spectrometry – MS), and require time-consuming analysis. Less accurate, but much cheaper, are resistive gas sensors. These sensors use porous materials and adsorptiondesorption processes, determining their physical parameters. We consider the problems of applying resistive gas sensors to breath analysis. Recent advances were underlined, showing that these economical gas sensors can be efficiently employed to analyse breath samples. General problems of applying resistive gas sensors are considered and illustrated with examples, predominantly related to commercial sensors and their long-term performance. A setup for collection of breath samples is considered and presented to point out the crucial parts and problematic issues.

  • Expedited antenna optimization with numerical derivatives and gradient change tracking
    • Anna Pietrenko-Dąbrowska
    • Sławomir Kozieł
    2020 Pełny tekst ENGINEERING COMPUTATIONS

    Design automation has been playing an increasing role in the development of novel antenna structures for various applications. One of its aspects is electromagnetic (EM)-driven design closure, typically applied upon establishing the antenna topology, and aiming at adjustment of geometry parameters to boost the performance figures as much as possible. Parametric optimization is often realized using local methods given usually reasonable quality of the initial designs obtained at the topology evolution stage. The major difficulty here is high computational cost associated with a large number of EM simulations required by conventional methods, both gradient and derivative-free routines. Possible workarounds including surrogate-assisted variable-fidelity methods (e.g., space mapping) face similar problems because the underlying low-fidelity model is often optimized directly. This paper proposes an expedited version of the trust-region (TR) gradient-based algorithm with numerical derivatives. A considerable reduction of the number of EM simulations is achieved by monitoring the behavior of the gradient throughout the algorithm run and omitting the finite-differentiation updates upon detecting stable patterns for particular parameter sensitivities. The proposed approach is benchmarked against the standard TR algorithm as well as the recently reported accelerated TR frameworks. Improved performance is consistently demonstrated for all considered test cases.

  • Expedited Design Closure of Antenna Input Characteristics by Trust Region Gradient Search and Principal Component Analysis
    • Jon Tomasson
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2020 Pełny tekst IEEE Access

    Optimization-based parameter tuning has become an inherent part of contemporary antenna design process. For the sake of reliability, it is typically conducted at the level of full-wave electromagnetic (EM) simulation models. This may incur considerable computational expenses depending on the cost of an individual EM analysis, the number of adjustable variables, the type of task (local, global, single-/multi-objective optimization), and the constraints involved. For these reasons, utilization of conventional algorithms is often impractical. This paper proposes a novel gradient-based algorithm with numerical derivatives for expedited antenna optimization. The improvement of computational efficiency is obtained by employing a rank-one Broyden formula and restricting finite differentiation sensitivity updates to the principal directions of the Jacobian matrix, i.e., those corresponding to the most significant changes of the antenna responses. Comprehensive numerical validation carried out using three wideband antennas indicates that the presented methodology offers considerable savings of sixty percent with respect to the reference trust-region algorithm. At the same time, virtually no degradation of the design quality is observed. Furthermore, algorithm reliability is greatly improved (while offering comparable computational efficiency) over the recent state-of-the-art accelerated gradient-based procedures.

  • Expedited Feature-Based Quasi-Global Optimization of Multi-Band Antenna Input Characteristics with Jacobian Variability Tracking
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2020 Pełny tekst IEEE Access

    Design of modern antennas relies—for reliability reasons—on full-wave electromagnetic simulation tools. In addition, increasingly stringent specifications pertaining to electrical and field performance, growing complexity of antenna topologies, along with the necessity for handling multiple objectives, make numerical optimization of antenna geometry parameters a highly recommended design procedure. Conventional algorithms, particularly global ones, entail often-unmanageable computational costs, so alternative approaches are needed. This work proposes a novel method for cost-efficient globalized design optimization of multi-band antennas incorporating the response feature technology into the trustregion framework. It allows for unequivocal allocation of the antenna resonances even for poor initial designs, where conventional local algorithms fail. Furthermore, the algorithm is accelerated by means of Jacobian variability tracking, which reduces the number of expensive finite-differentiation updates. Two real-world antenna design cases are used for demonstration purposes. The optimization cost is comparable to that of local routines while ensuring nearly global search capabilities.

  • Expedited Globalized Antenna Optimization by Principal Components and Variable-Fidelity EM Simulations: Application to Microstrip Antenna Design
    • Jon Tomasson
    • Anna Pietrenko-Dąbrowska
    • Sławomir Kozieł
    2020 Pełny tekst Electronics

    Parameter optimization, also referred to as design closure, is imperative in the development of modern antennas. Theoretical considerations along with rough dimension adjustment through supervised parameter sweeping can only yield initial designs that need to be further tuned to boost the antenna performance. The major challenges include handling of multi-dimensional parameter spaces while accounting for several objectives and constraints. Due to complexity of modern antenna topologies, parameter interactions are often involved, leading to multiple local optima as well as difficulties in identifying decent initial designs that can be improved using local procedures. In such cases, global search is required, which is an expensive endeavor, especially if full-wave electromagnetic (EM) analysis is employed for antenna evaluation. This paper proposes a novel technique accommodating the search space exploration using local kriging surrogates and local improvement by means of trust-region gradient search. Computational efficiency of the process is achieved by constructing the metamodels over appropriately defined affine subspaces and incorporation of coarse-mesh EM simulations at the exploratory stages of the optimization process. The resulting framework enables nearly global search capabilities at the costs comparable to conventional gradient-based local optimization. This is demonstrated using two antenna examples and comparative studies involving multiple-start local tuning.

  • Expedited optimization of antenna input characteristics with adaptive Broyden updates
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2020 Pełny tekst ENGINEERING COMPUTATIONS

    Simulation-driven adjustment of geometry and/or material parameters is a necessary step in the design of contemporary antenna structures. Due to their topological complexity, other means, such as supervised parameter sweeping, does not usually lead to satisfactory results. On the other hand, rigorous numerical optimization is computationally expensive due to a high cost of underlying full-wave electromagnetic (EM) analyses, otherwise required to assess antenna performance in a reliable manner. Design closure normally requires a local search, often carried out by means of gradient-based procedures. In this work, accelerated trust-region gradient-search algorithm is proposed for expedited optimization of antenna structures. In our approach, finite differentiation conventionally used to estimate the antenna response Jacobian is replaced, for selected variables, by a rank-one Broyden updating formula. The selection of variables is governed by the alignment between the direction of the recent design relocation and the coordinate system axes. Operation and performance of the algorithm is demonstrated using a set of benchmark wideband antennas. Comprehensive numerical validation indicates significant computational savings of up to 70 percent that can be achieved without compromising the design quality in a significant manner.

  • Expedited Yield Optimization of Narrow- and Multi-Band Antennas Using Performance-Driven Surrogates
    • Anna Pietrenko-Dąbrowska
    • Sławomir Kozieł
    • Muath Al-hasan
    2020 Pełny tekst IEEE Access

    Uncertainty quantification is an important aspect of engineering design, also pertaining to the development and performance evaluation of antenna systems. Manufacturing tolerances as well as other types of uncertainties, related to material parameters (e.g., substrate permittivity) or operating conditions (e.g., bending) may affect the antenna characteristics. In the case of narrow- or multi-band antennas, this usually leads to frequency shifts of the operating bands. Quantifying these effects is imperative to adequately assess the design quality, either in terms of the statistical moments of the performance parameters or the yield. Reducing the antenna sensitivity to parameter deviations is even more essential when increasing the probability of the system satisfying the prescribed requirements is of concern. The prerequisite of such procedures is statistical analysis, normally carried out at the level of full-wave electromagnetic (EM) analysis. While necessary to ensure reliability, it entails considerable computational expenses, often prohibitive. Following the recently fostered concept of constrained modeling, this paper proposes a simple technique for rapid surrogate-assisted yield optimization of narrow- and multi-band antennas. The keystone of the approach is an appropriate definition of the optimization domain. This is realized by considering a few pre-optimized designs that represent the directions of the major changes of the antenna resonant frequencies and operating bands. Due to a small volume of such a domain, an accurate replacement model can be established therein using a small number of training samples, and employed to improve the antenna yield. Verification results obtained for a ring-slot antenna, a dual-band and a triple-band uniplanar dipoles indicate that the optimization process can be accomplished at low cost of a few dozen of EM simulations: 62, 74 and 132 EM simulations, respectively. Result reliability is validated through comparisons with EM-based Monte Carlo simulations.

  • Experience Based Clinical Decision Support Systems: An Overview and Case Studies
    • Carlos Toro
    • Manuel Grana
    • Eider Sanchez
    • Cesar Sanin
    • Edward Szczerbicki
    2020

    This chapter briefly overviews the evolution of the application of the Decisional DNA and the Set of Experience Knowledge Structure (SOEKS) in the medical domain and in particular in the specific case of the experience-based decision support systems. Decisional DNA, as a knowledge representation structure, offers great possibilities on gathering explicit knowledge of formal decision events as well as a tool for decision making processes. The chapter collates more than 10 years of continuous application of the aforesaid techniques into the medical domain in particular for supporting the clinical decision scenario.

  • Experience-Based Cognition for Driving Behavioral Fingerprint Extraction
    • Haoxi Zhang
    • Fei Li
    • Juan Wang
    • Yang Zhou
    • Cesar Sanin
    • Edward Szczerbicki
    2020 Pełny tekst CYBERNETICS AND SYSTEMS

    ABSTRACT With the rapid progress of information technologies, cars have been made increasingly intelligent. This allows cars to act as cognitive agents, i.e., to acquire knowledge and understanding of the driving habits and behavioral characteristics of drivers (i.e., driving behavioral fingerprint) through experience. Such knowledge can be then reused to facilitate the interaction between a car and its driver, and to develop better and safer car controls. In this paper, we propose a novel approach to extract the driver’s driving behavioral fingerprints based on our conceptual framework Experience-Oriented Intelligent Things (EOIT). EOIT is a learning system that has the potential to enable Internet of Cognitive Things (IoCT) where knowledge can be extracted from experience, stored, evolved, shared, and reused aiming for cognition and thus intelligent functionality of things. By catching driving data, this approach helps cars to collect the driver’s pedal and steering operations and store them as experience; eventually, it uses obtained experience for the driver’s driving behavioral fingerprint extraction. The initial experimental implementation is presented in the paper to demonstrate our idea, and the test results show that it outperforms the Deep Learning approaches (i.e., deep fully connected neural networks and recurrent neural networks/Long Short-Term Memory networks).

  • Experimental analysis of wear resistance of compacts of fine-dispersed iron powder and tungsten monocarbide nanopowder produced by impulse pressing
    • Anatoly Bragov
    • Leonid Igumnov
    • Alexander Konstantinov
    • Andrey Lomunov
    • Evgeny Rusin
    • Victor Eremeev
    2020 Pełny tekst WEAR

    The paper presents the results of studying the structure and wear resistance of compacts produced from fine dispersed reduced iron powder (average particle size 3–mu m) with the addition of tungsten carbide (WC) nanopowder with the average particle size of 25–30 nm. The mass fraction of tungsten carbide (wolfram carbide) in the powder composition was 5% and 10% of the total mass. Impulse pressing was conducted using the modified Kolsky method at compacting temperatures of 20 °C to 300 °C. The produced compacts had relative density of over 90%.

  • Experimental and computational study on mechanical behaviour of carpentry corner log joints
    • Paweł Kłosowski
    • Anna Pestka
    • Marcin Krajewski
    • Izabela Lubowiecka
    2020 Pełny tekst ENGINEERING STRUCTURES

    This work concerns experimental and numerical research on carpentry joints used in historic wooden buildings in southeastern Poland and western Ukraine. These structures are mainly sacred buildings, and the types of corner log joints characteristic of this region are primarily saddle-notch and dovetail joints; thus, these two types of joints were analysed in this study. The modelling of historic timber structures is a complex issue, so the following steps are necessary to obtain accurate solutions: verification, validation and uncertainty quantification. The first and third steps were performed in a previous study, so the current research aimed to validate the numerical models and perform simulations of carpentry joints. Herein, the authors created finite element models of two types of joints and subsequently analysed the mechanical behaviour of these joints. Due to issues concerning model validation, the authors designed a testing stand for corner joints, which formed a part of a biaxial testing machine. The joints were subjected to horizontal loads (deformations), which may cause damage to the connection. Thus, special parts were designed for the stand, which made it possible to fix the joint and prevented eccentric forces that could possibly damage the machine during testing. The authors presented the differences and similarities in the behaviour of both types of joints, emphasizing the corresponding advantages and disadvantages. In addition, the authors determined which type of joint was the most susceptible to damage and what elements failed first. This paper also showed the complexity of modelling timber structures and the accuracy of the proposed numerical models for both types of joints through comparisons of the numerical and experimental results. This work primary addressed the problems in accurately reflecting material, load and boundary conditions in numerical modelling of tested carpentry corner log joints.

  • Experimental and DFT insights into an eco-friendly photocatalytic system toward environmental remediation and hydrogen generation based on AgInS2 quantum dots embedded on Bi2WO6
    • Patrycja Parnicka
    • Alicja Mikolajczyk
    • Henry P. Pinto
    • Wojciech Lisowski
    • Tomasz Klimczuk
    • Grzegorz Trykowski
    • Beata Bajorowicz
    • Adriana Zaleska-Medynska
    2020 APPLIED SURFACE SCIENCE

    Bismuth tungstate (Bi2WO6) can work as a photocatalyst but suffers from rapid recombination of photogenerated charge carriers. Herein, density functional theory (DFT) simulations revealed that the formation of a thermodynamically stable AgInS2(112)/Bi2WO6(010) heterojunction could promote charge separation and enhance the photoactivity of Bi2WO6. To confirm these theoretical predictions, a new type of photocatalysts in the form of Bi2WO6 flower-like microspheres decorated with different amounts of AgInS2 quantum dots (QDs) was obtained using a three-step procedure. The optimized system, obtained by embedding 1 wt% AgInS2 QDs on a Bi2WO6 matrix, possessed an enhanced photocatalytic activity for both phenol degradation and water splitting under visible light irradiation (λ > 420 nm), as well as good reusability and stability during prolonged storage. Finally, DFT calculations of the adsorption energies of reagents (O2, H2O, and H2 molecules) on Bi2WO6 and AgInS2/Bi2WO6 surfaces showed that the surface of the AgInS2(112)/Bi2WO6(010) interface was more active, allowing this system to strongly interact with surrounding species such as H2, O2, and H2O and thereby inducing photocatalytic oxidation of OH– to •OH, reduction of O2 to O2 •– or reduction of H+ to H2.

  • Experimental and Numerical Investigation of Mechanical Properties of Lightweight Concretes (LWCs) with Various Aggregates
    • Marzena Kurpińska
    • Tomasz Ferenc
    2020 Pełny tekst Materials

    High requirements for the properties of construction materials and activities directed at environment protection are reasons to look for new solutions in concrete technology. This research was directed at solutions affecting the reduction of energy consumption and CO2 emissions. The use of lightweight concretes (LWCs) allows one to meet both conditions at the same time. The purpose of the research presented in this paper was to investigate the abilities of using lightweight aggregates (LWAs) of the following types: 2 and 4 mm granulated expanded glass aggregate (GEGA) as ingredients with excellent insulating properties and 8 mm granulated fly ash aggregate (GAA) as an ingredient with a relatively high resistance to crushing. The influence of the percentage participation of each aggregate in all LWCs was variable and amounted to 0%, 25%, 50%, 75%, and 100%. A series of 15 LWC mixes were prepared for various LWA participations and for a constant water–cement ratio (w/c = 0.5). Concrete tests were carried out for the following criteria: density, porosity, compressive strength, and the modulus of elasticity. In order to fully analyze fracture processes in LWCs with the participation of GEGA and GAA and to assess the correctness of the results obtained during the experiments, numerical models that corresponded to both geometrical and load diagrams of elements under research were created. The numerical analyses of the LWCs were conducted by means of the conventional finite element method (FEM).

  • Experimental and numerical investigations of ultimate strength of imperfect stiffened plates of different slenderness
    • Krzysztof Wołoszyk
    • Yordan Garbatov
    • Jakub Kowalski
    • Leszek Samson
    2020 Pełny tekst Polish Maritime Research

    The objective of this study is to analyse the behaviour of compressed stiffened plates of different slenderness using experimental and numerical methods. The presented results are part of a long-term project to investigate the ultimate strength of geometrically imperfect structures subjected to different degradation phenomena, including corrosion degradation and locked cracks. Several specimens were subjected to a uniaxial compressive force, and the most important quantities related to the structural behaviour were captured and analysed. A finite element model, accounting for material and geometrical nonlinearities and initial geometrical imperfections, was developed using the commercial software ANSYS. The residual welding-induced stresses were measured in the middle cross-section for two specimens. The initial imperfection was identified by employing a close-range photogrammetry approach. It was concluded that the numerical analyses, based on the finite element model, predict the ultimate strength of stiffened plates accurately, although some deviations were also observed. The detailed analysis with the indication of possible uncertainty is presented, and several conclusions are derived.

  • Experimental and Numerical Study on Dynamics of Two Footbridges with Different Shapes of Girders
    • Anna Banaś
    • Robert Jankowski
    2020 Pełny tekst Applied Sciences-Basel

    The paper presents the experimental and numerical results of the dynamic system identification and verification of the behavior of two footbridges in Poland. The experimental part of the study involved vibration testing under different scenarios of human-induced load, impulse load, and excitations induced by vibration exciter. Based on the results obtained, the identification of dynamic parameters of the footbridges was performed using the peak-picking method. With the impulse load applied to both structures, determination of their natural vibration frequencies was possible. Then, based on the design drawings, detailed finite element method (FEM) models were developed, and the numerical analyses were carried out. The comparison between experimental and numerical results obtained from the modal analysis showed a good agreement. The results also indicated that both structures under investigation have the first natural bending frequency of the deck in the range of human-induced excitation. Therefore, the risk of excessive structural vibrations caused by pedestrian loading was then analysed for both structures. The vibration comfort criteria for both footbridges were checked according to Sétra guidelines. In the case of the first footbridge, the results showed that the comfort criteria are fulfilled, regardless of the type of load. For the second footbridge, it was emphasized that the structure meets the assumptions of the guidelines for vibration severability in normal use; nevertheless, it is susceptible to excitations induced by synchronized users, even in the case of a small group of pedestrians.

  • Experimental and predicted physicochemical properties of monopropanolamine-based deep eutectic solvents
    • Bartosz Nowosielski
    • Marzena Jamrógiewicz
    • Justyna Łuczak
    • Maciej Śmiechowski
    • Dorota Warmińska
    2020 Pełny tekst JOURNAL OF MOLECULAR LIQUIDS

    In this work, the novel deep eutectic solvents (DESs) based on 3-amino-1-propanol (AP) as hydrogen bond donor (HBD) and tetrabutylammonium bromide (TBAB) or tetrabutylammonium chloride (TBAC) or tetraethylammonium chloride (TEAC) as hydrogen bond acceptors (HBAs) were synthesized with different molar ratios of 1:4, 1:6 and 1:8 salt to AP. Fourier Transform Infrared Spectroscopy measurements were performed to provide an evidence of any chemical structure changes. Physical properties of the prepared DESs including densities, viscosities, refractive indices and sound velocities were measured within the temperature range of 293.15 – 333.15 K at the pressure of 0.1 MPa. They were analysed in terms of estimating the effect of HBA to HBD molar ratio, anion and length of alkyl chain in a salt, and their temperature dependences were fitted by empirical equations. Thermal expansion coefficients and activation energies for viscous flow were obtained accordingly. Moreover, experimental values of density and refractive index were compared with predicted ones. For prediction of density, Rackett equation modified by Spencer and Danner and the mass connectivity index-based method were used, while refractive index was estimated by the atomic contribution method.

  • Experimental certification of an informationally complete quantum measurement in a device-independent protocol
    • Massimiliano Smania
    • Piotr Mironowicz
    • Mohamed Navareg
    • Marcin Pawłowski
    • Adan Cabello
    • Mohamed Bourennane
    2020 Pełny tekst Optica

    Minimal informationally complete positive operator-valued measures (MIC-POVMs) are special kinds of measurement in quantum theory in which the statistics of their d2-outcomes are enough to reconstruct any d-dimensional quantum state. For this reason, MIC-POVMs are referred to as standard measurements for quantum information.Here, we report an experiment with entangled photon pairs that certifies, for what we believe is the first time, a MIC-POVM for qubits following a device-independent protocol (i.e., modeling the state preparation and the measurement devices as black boxes, and using only the statistics of the inputs and outputs). Our certification is achieved under the assumption of freedom of choice, no communication, and fair sampling.

  • Experimental investigation of joint with positive eccentricity in CFS truss
    • Małgorzata Gordziej-Zagórowska
    • Elżbieta Urbańska-Galewska
    • Patryk Deniziak
    2020 Pełny tekst THIN-WALLED STRUCTURES

    Due to technological restrictions, in the case of trusses made of CFS open cross-sections, positive eccentricities in the truss joints have become very frequent. Therefore studies concerning the load-bearing capacity of truss joints with positive eccentricity were undertaken. It was assumed that the resistance of cold-formed steel (CFS) open cross-section truss joints located on compression chords and with positive eccentricity is greater than that which results from hitherto known methods of steel structure dimensioning. In order to confirm the hypothesis, experimental studies were conducted. A series of 5 full-scale research models was subjected to destructive tests to determine the deformation forms and strains of the hat-section walls in the area of the eccentric joint. Forms of truss chord stability loss under compression and bending were identified. The course of research and analysis of results were described in the article. Than comparative analysis of the outcomes of the experimental tests and the results of analytical calculations carried out according to Eurocode standards was done, and the obtained results confirmed the usefulness of the undertaken research. The obtained results did not allow for explicit confirmation of the research hypothesis at this stage, but constituted the basis for validation of the numerical model which has been elaborated. Currently, the authors carry out a variety of numerical analysis.

  • Experimental Investigations on the Influence of Coil Arrangement on Melting/Solidification Processes
    • Rafał Andrzejczyk
    • Przemysław Kozak
    • Tomasz Muszyński
    2020 Pełny tekst ENERGIES

    The latent heat thermal energy storage units are very popular because of their high energy density and almost close to constant temperature during the charging/discharging. In the present study has been proposed new shell-and-coil geometry with a shifted coil position to enhance the performance of phase change thermal magazine. The experimental investigations have been performed both for the melting and solidification process of coconut oil for constant wall temperature conditions. The experiments have been carried out for cylindrical as well as coil shape geometry of the TES unit. In the case of annular TES, the copper tube with outer diameter d = 10 mm and total length equal to 165 mm were used (4). In the case of shell-and-coil TES the coil has been also made of a copper tube but with an outer diameter d = 6 mm. The total length of the tube was 460 mm. However, the length of the tube element that has been used in the process of bending the coil had a total length equal to 360 mm. The rest of the tube was straight. The coil pitch was 15 mm and the outer coil diameter was 26 mm. The experiments have been conducted for the coil position at the top and the bottom of the tank. The results showed the influence of heat transfer geometry for phase change efficiency. The article presents the thermal characteristic of melting and solidification phenomena as well as their visual analysis. A significant impact of heat transfer geometry at the shape of the melting and solidification profile. The optimal performance has been achieved for shell-and-coil TES with a coil arranged at the top of the tank.

  • Experimental Research on Insufficient Water Lubrication of Marine Stern Tube Journal Bearing with Elastic Polymer Bush
    • Agnieszka Barszczewska
    2020 Pełny tekst Polish Maritime Research

    Water-lubricated bearings with polymer bushes are steadily gaining popularity due to their advantages, including environmental friendliness, relatively simple construction and long-term operation. Nevertheless, in practice instances of damage to such bearings occur due to insufficient or absent flow of the lubricating agent. In this study, experimental tests established that elastic polymer bush bearing is capable of operating without excessive wear for a period of at least 60 minutes under conditions of marginal water flow and typical loads for stern tube journal bearings of small ships.

  • Experimental Studies of Concrete-Filled Composite Tubes under Axial Short- and Long-Term Loads
    • Marcin Abramski
    • Piotr Korzeniowski
    • Krzysztof Klempka
    2020 Pełny tekst Materials

    The paper presents experimental studies on axially compressed columns made of concrete-filled glass fiber reinforced polymer (GFRP) tubes. The infill concrete was C30/37 according to Eurocode 2. The investigated composite pipes were characterized by different angles of fiber winding in relation to the longitudinal axis of the element: 20, 55 and 85 degrees. Columns of two lengths, 0.4 m and 2.0 m, were studied. The internal diameter and wall thickness of all the pipes were identical and amounted to 200 mm and 6 mm, respectively. The mean values of two mechanical properties, elasticity modulus and compression strength, were determined. These properties were determined for longitudinal compression and for circumferential tension. The graphs of longitudinal and peripheral deformations of polymer shells as a function of load level are presented both for empty tubes and for concrete-filled ones. The results of long-term investigations of three identically made 0.4 m high concrete-filled GFRP tubes are also presented.

  • Experimental Study on the Effectiveness of Polyurethane Flexible Adhesive in Reduction of Structural Vibrations
    • Natalia Lasowicz
    • Arkadiusz Kwiecień
    • Robert Jankowski
    2020 Pełny tekst Polymers

    The aim of the present study is to consider the idea of using polyurethane flexible adhesive in to reduce the vibrations in structures exposed to dynamic loads and evaluate their damping properties in relation to large deformations. Firstly, two aluminium cantilever beams, simulating structural elements (without and with polyurethane layer in the form of tape), were analysed, in order to check the damping of the unconstrained polymer layer. In the second stage of the study, a composite beam consisting of two aluminium flat beams bonded with polymer adhesive was considered, so as to check the damping of the constrained polymer layer. Dynamic parameters, such as modes of free vibrations, corresponding natural frequencies and damping ratios, were determined and compared. The third stage of the investigation was aimed at solving the problem of the additional mass of the applied polymer layer, which influences the frequencies and damping of the tested structure. A special separating procedure is proposed that makes it possible to calculate the corrected real values of the polymer layer’s damping. The results of the study clearly show that the response of the composite aluminium beam with and without polymer adhesive layer is mainly influenced by the layers’ thickness and the large strain deformation, in terms of its damping characteristics. The use of polymer adhesive layers in constrained and unconstrained conditions leads to a significant reduction in the vibrations of tested beams, while preserving their stiness at nearly the same level. The applied analysis procedure made it possible for us to separate the damping properties of the analysed polymer layers and evaluate them independently with respect to the influence of integrated structural elements on damping.

  • Experimental study on the selected aspects of bow thruster generated flow field at ship zero-speed conditions
    • Teresa Abramowicz-Gerigk
    • Mirosław Gerigk
    2020 OCEAN ENGINEERING

    The paper presents the results of experimental study on the interaction between the bow thrusters understood as the flow field changes generated by bow tunnel thruster in deep water conditions operated as a single and twin units. The research was limited to zero-speed case for the ship dead in the water. The influence of the hull form and jet spread between the neighbouring thrusters for several combinations of the applied bow thruster propeller revolutions has been discussed. The results of the flow field measurements - velocity field, volume of fluid rate, mean velocity and thrust have been compared with the measurements of hydrodynamic forces generated by the bow thrusters on the hull. Both experiments were conducted at zero-speed using the same large physical man-manned model of a car-passenger ferry in 1:16 scale.