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Gdańsk University of Technology

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  • A new 1-nitro-9-aminoacridine derivative targeting yeast topoisomerase II able to overcome fluconazole-resistance
    • Kamila Rząd
    • Ewa Paluszkiewicz
    • Iwona Gabriel
    2021 BIOORGANIC & MEDICINAL CHEMISTRY LETTERS

    Fungal resistance remains a significant threat and a leading cause of death worldwide. Thus, overcoming microbial infections have again become a serious clinical problem. Although acridine derivatives are widely analyzed as anticancer agents, only a few reports have demonstrated their antifungal activity. In an effort to develop biologically active antifungals, twelve novel C-857 (9-(2′ -hydroxyethylamino)-1-nitroacridine) and C-1748 (9-(2′ -hydroxyethylamino)-4-methyl-1-nitroacridine) derivatives were synthesized. The evaluation of biological properties suggests that starting compounds: C-1748, C-857 and IE3 (2-[(4-methyl-1-nitroacridin-9- yl)amino]ethyl lysinate), IE4 (2-[(1-nitroacridin-9-yl)amino]ethyl lysinate) antifungal mode of action differ from that determined for IE5 (N′ -{3-[(4-methyl-1-nitroacridin-9-yl)amino]propyl}lysinamide), IE6 (N′ -{3-[(1-nitroacridin-9-yl)amino]propyl}lysinamide) and IE10 (3,3′ -Bis-(1-nitroacridin-9-ylamino) aminoethylaminoethylaminoethylamine). Although MIC values determined for the latter were higher, in contrast to C-857 and C-1748, newly synthesized IE5, IE6 and IE10 reduced C. albicans hyphal growth in different inducing media. Those compounds also exhibited antibiofilm activity, whereas IE10 was the most effective. Moreover, only IE6 exhibited antifungal activity against fluconazole resistant C. albicans strains with MICs values in the range of 16–64 μg mL- 1. Our results also indicate that, in contrast to other analyzed derivatives, novel synthetized compounds IE6 and IE10 with antifungal activity target yeast topoisomerase II activity.

  • A New Adaptive Method for the Extraction of Steel Design Structures from an Integrated Point Cloud
    • Paweł Burdziakowski
    • Angelika Zakrzewska
    2021 Full text SENSORS

    The continuous and intensive development of measurement technologies for reality modelling with appropriate data processing algorithms is currently being observed. The most popular methods include remote sensing techniques based on reflected-light digital cameras, and on active methods in which the device emits a beam. This research paper presents the process of data integration from terrestrial laser scanning (TLS) and image data from an unmanned aerial vehicle (UAV) that was aimed at the spatial mapping of a complicated steel structure, and a new automatic structure extraction method. We proposed an innovative method to minimize the data size and automatically extract a set of points (in the form of structural elements) that is vital from the perspective of engineering and comparative analyses. The outcome of the research was a complete technology for the acquisition of precise information with regard to complex and high steel structures. The developed technology includes such elements as a data integration method, a redundant data elimination method, integrated photogrammetric data filtration and a new adaptive method of structure edge extraction. In order to extract significant geometric structures, a new automatic and adaptive algorithm for edge extraction from a random point cloud was developed and presented herein. The proposed algorithm was tested using real measurement data. The developed algorithm is able to realistically reduce the amount of redundant data and correctly extract stable edges representing the geometric structures of a studied object without losing important data and information. The new algorithm automatically self-adapts to the received data. It does not require any pre-setting or initial parameters. The detection threshold is also adaptively selected based on the acquired data.

  • A New Approach to the PWM Modulation for the Multiphase Matrix Converters Supplying Loads with Open-End Winding.
    • Paweł Szczepankowski
    • Natalia Strzelecka
    • Enrique Romero-Cadaval
    2021 Full text ENERGIES

    This article presents three variants of the Pulse Width Modulation (PWM) for the Double Square Multiphase type Conventional Matrix Converters (DSM-CMC) supplying loads with the open-end winding. The first variant of PWM offers the ability to obtain zero value of the common-mode voltage at the load's terminals and applies only six switches within the modulation period. The second proposal archives for less Total Harmonic Distortion (THD) of the generated load voltage. The third variant of modulation concerns maximizing the voltage transfer ratio, minimizing the number of switching, and the common-mode voltage cancellation. The discussed modulations are based on the concept of sinusoidal voltage quadrature signals, which can be an effective alternative to the classic space-vector approach. In the proposed approach, the geometrical arrangement of basic vectors needed to synthesize output voltages is built from the less number of vectors, which is equal to the number of the matrix converter's terminals. The PWM duty cycle computation is performed using only a second-order determinant of the voltages coordinate matrix without using trigonometric functions. A new approach to the PWM duty cycles computing and the load voltage synthesis by 5x5 and 12x12 topologies has been verified using the PSIM simulation software.

  • A new concept of contemporary marketing
    • Anna Drapińska
    2021

    Purpose: This conceptual paper aims to propose a new concept of marketing that responds well to the needs of a changing world, taking into account the continuous development of the service economy and the revolution in the development of the Internet and related tools. Methodology/Approach: The proposed concept is based on well-researched theories: service marketing, experience marketing, relationship marketing and digital marketing (4.0). An in-depth review of marketing literature has been conducted. The proposed concept uses such terms as interactions, relationships, experiences, and digital marketing. Findings: The main achievement is a new concept of contemporary marketing. Its essence is the creation by organizations of long-term relationships with customers, through interactions and consistent customer experiences both in the offline and online world. Originality/value: The paper proposes a new look at contemporary marketing, indicates its elements and essence and contributes both to the development of the theory and research in marketing.

  • A New Direct-Sequence Spread Spectrum Signal Detection Method for Underwater Acoustic Communications in Shallow-Water Channel
    • Iwona Kochańska
    2021 Full text Vibrations in Physical Systems

    Direct-Sequence Spread Spectrum (DSSS) is one of the modulation and coding techniques used in Underwater Acoustic Communication (UAC) systems for reliable data transmision even at low signal levels. However, in a shallow water channel, there is a strong multipath propagation which causes a phase fluctuation of the received signal, affecting the performance of the spread-spectrum system. The article presents a differential method for DSSS signal detection. It is based on the calculation of the correlation coefficient of adjacent segments of signal at the output of filter matched to the spreading sequence used in the transmitter. A positive value of the correlation coefficient means that a given modulation symbol carries the same information bit as the previous one; a negative value means that the opposite bit has been transmitted. The reliability of the proposed method has been compared to classical method of DSSS signal detection, which consists in detecting the information directly from the signal at the output of the matched filter. Simulation and measurement tests of underwater acoustic communications in strong multipath propagation conditions have shown that the proposed method allows obtaining lower values of the DSSS transmission Bit Error Rate (BER) than the classical detection technique while maintaining the same data transmission rate.

  • A new multi-process collaborative architecture for time series classification
    • Zhiwen Xiao
    • Xingtao Xu
    • Haoxi Zhang
    • Edward Szczerbicki
    2021 Full text KNOWLEDGE-BASED SYSTEMS

    Time series classification (TSC) is the problem of categorizing time series data by using machine learning techniques. Its applications vary from cybersecurity and health care to remote sensing and human activity recognition. In this paper, we propose a novel multi-process collaborative architecture for TSC. The propositioned method amalgamates multi-head convolutional neural networks and capsule mechanism. In addition to the discovery of the temporal relationship within time series data, our approach derives better feature extraction with different scaled capsule routings and enhances representation learning. Unlike the original CapsNet, our proposed approach does not need to reconstruct to increase the accuracy of the model. We examine our proposed method through a set of experiments running on the domain-agnostic TSC benchmark datasets from the UCR Time Series Archive. The results show that, compared to a number of recently developed and currently used algorithms, we achieve 36 best accuracies out of 128 datasets. The accuracy analysis of the proposed approach demonstrates its significance in TSC by offering very high classification confidence with the potential of making inroads into plentiful future applications.

  • A note on the applications of artificial intelligence in the hospitality industry: preliminary results of a survey
    • Joanna Citak
    • Mieczysław Owoc
    • Paweł Weichbroth
    2021 Full text

    Intelligent technologies are widely implemented in different areas of modern society but specific approaches should be applied in services. Basic relationships refer to supporting customers and people responsible for services offering for these customers. The aim of the paper is to analyze and evaluate the state-of-the art of artificial intelligence (AI) applications in the hospitality industry. Our findings show that the major deployments concern in-person customer services, chatbots and messaging tools, business intelligence tools powered by machine learning, and virtual reality & augmented reality. Moreover, we performed a survey (n = 178), asking respondents about their perceptions and attitudes toward AI, including its implementation within a hotel space. The paper attempts to discuss how the hotel industry can be motivated by potential customers to apply selected AI solutions. In our opinion, these results provide useful insights for understanding the phenomenon under investigation. Nevertheless, since the results are not conclusive, more research is still needed on this topic. Future studies may concern both qualitative and quantitative methods, devoted to developing models that: a) quantify the potential benefits and risks of AI implementations, b) determine and evaluate the factors affecting the AI adoption by the customers, and c) measure the user (guest) experience of the hotel services, fueled by AI-based technologies.

  • A Novel Versatile Decoupling Structure and Expedited Inverse-Model-Based Re-Design Procedure for Compact Single-and Dual-Band MIMO Antennas
    • Muhammad Abdullah
    • Sławomir Kozieł
    2021 Full text IEEE Access

    Multiple-input multiple-output (MIMO) antennas are considered to be the key components of fifth generation (5G) mobile communications. One of the challenges pertinent to the design of highly integrated MIMO structures is to minimize the mutual coupling among the antenna elements. The latter arises from two sources, the coupling in the free space and the coupling currents propagating on a ground plane. In this paper, an array of H-shaped parasitic patches is proposed as a decoupling structure for compact MIMO antennas to reduce propagation of the coupling currents on a shared ground plane. The proposed decoupling structure is generic, and it can be applied to different antenna configurations as demonstrated in the work. Furthermore, it is employed to develop a new high-performance compact dual-band MIMO structure featuring acceptable level of element coupling at both operating frequencies. The design is validated both numerically and experimentally. The mutual coupling levels are less than -17 dB and -20 dB, with the total efficiency of 89% and 90%, and the realized gain of 6.6 dB and 7 dB at the two resonant frequencies of 5 GHz and 6 GHz, respectively. Topological complexity of the compact MIMO systems featuring elaborated decoupling structures, a large number of geometry parameters, as well as the necessity of handling multiple performance figures, constitute the major challenges of antenna design, in particular, its re-design for various specifications. To alleviate these difficulties, the paper also provides a procedure for rapid geometry scaling of the dual-band MIMO antennas. Our approach is based on inverse surrogate modeling methods, and results in numerically-derived expressions that enable a precise control over the operating antenna bands within broad ranges thereof (from 4 GHz to 8 GHz for the lower band, and from 1.1 to 1.3 ratio of the upper to lower operating frequency). The aforementioned procedure is accompanied by an optimization-based design refinement scheme. A practical utility of the procedure is corroborated using multiple verification case studies as well as physical measurements of the antenna designed for the exemplary set of performance specifications.

  • A Panel Analysis of the Impact of Green Transformation and Globalization on the Labor Share in the National Income
    • Małgorzata Gawrycka
    • Anna Szymczak
    2021 Full text ENERGIES

    This study aims to examine the impact of green transition and globalization processes on changes in the labour share. The study covers 76 national economies diversified in development, global production share and energy transition stage from 2000 to 2018. Based on the Total Economy Database data, panel models of the relationship between green transition, globalization and the labour share in the national income were estimated. The conducted Breusch–Pagan and Hausman tests proved the validity of using fixed-effects models. We confirmed the research hypothesis that the openness of the economy contributes to a decline in the labour share. The openness of the economy resulting from globalization reduces the labour share in the national income. We do not confirm hypotheses that suggest energy transition contributes to a reduction in the labour share and that the labour share will decline in the post-crisis period due to the lower bargaining power of workers. Changes in the labour share should be of interest to government representatives who influence the shape and implementation of economic policy, especially in employment policy, education, and investment policy, mainly aimed at the green transformation.

  • A Pilot Study on Machining Difficult-to-Cut Materials with the Use of Tools Fabricated by SLS Technology
    • Mariusz Deja
    • Dawid Zieliński
    2021 Full text Materials

    The growing use of contemporary materials in various industrial sectors, such as aerospace, automotive, as well as the oil and gas industry, requires appropriate machining methods and tools. Currently, apart from the necessity to obtain high-dimensional and shape accuracy, the efficiency and economic aspects of the selected manufacturing process are equally important, especially when difficult-to-cut materials, such as hard and brittle ceramics, have to be machined. In the research presented in this paper, a prototype tool fabricated from polyamide powder by the SLS method was used in flat-lapping of Al2O3 ceramics, showing the promising potential and efficacy of rapid tooling and manufacturing in the area of abrasive machining. The influence of the selected input process factors, such as machining time, the type of abrasive suspension, kinematic parameters, and unit pressure, on technological effects, was analyzed. The microscopic observations of the active surface of the prototype tool showed its reinforcement with loose diamond abrasive particles (size D107), resulting in the effective material removal and improved surface finish of Al2O3 ceramic samples. The directions for further development of tools fabricated by the SLS method for applications in abrasive machining were also envisaged by the authors.

  • A pilot study to assess manufacturing processes using selected point measures of vibroacoustic signals generated on a multitasking machine
    • Mariusz Deja
    • Roksana Licow
    2021 Full text INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY

    The article presents the method for the evaluation of selected manufacturing processes using the analysis of vibration and sound signals. This method is based on the use of sensors installed outside the machining zone, allowing to be used quickly and reliably in real production conditions. The article contains a developed measurement methodology based on the specific location of microphones and vibration transducers mounted on the tested object, in this case on a four-axis CNC ST20Y Haas lathe. A mobile phone was integrated into the measuring system and used to control the measurement process. The results from the analysis of vibration and sound signals recorded during different machining operations are presented. They refer to selected working conditions of a machine tool depending on switching the coolant supply on or off and different machine loads caused by various technological processing as well as the various speed of the positioning movements. The analysis was carried out using selected point measures describing the vibroacoustic signals. The synthesis conducted on the basis of results from the experiments indicates the validity of using vibration and acoustic signals, recorded outside the machining area, to evaluate material removal processes that are diverse in terms of kinematics and processing conditions. It indicates the possibility of using proposed point measures of vibroacoustic signals in the diagnostic aspects of the machine tools to achieve high dimension and shape accuracy and to evaluate the condition of the technological devices in terms of their optimal efficiency. Presented methodology can be used as a supporting tool in the CAD/CAM software for a better selection of appropriate cutting parameters and for a wireless control of manufacturing systems consisting of several machine tools.

  • A Qualitative Study on Non-functional Requirements in Agile Software Development
    • Aleksander Jarzębowicz
    • Paweł Weichbroth
    2021 Full text IEEE Access

    Widespread use of agile software development (ASD) methods can be observed nowadays. Non-functional requirements (NFRs) are often reported to be a problematic issue for agile projects, since ASD methods tend to neglect NFRs while focusing on incremental delivery of functional features. Despite that, only very few studies have explored the requirements engineering practices used in ASD and dedicated particularly to NFRs. Objective: We aimed to identify and investigate the practices used in industrial ASD projects to identify, elicit and document NFRs. Method: We conducted a systematic literature review (SLR) and used its findings to prepare an interview guide. We then conducted a series of semi-structured interviews with 10 experienced practitioners. Results: The SLR revealed a number of strategies related to the timing of NFR identification as well as 13 elicitation practices and 20 documentation techniques. At least some of these findings show discrepancies between ASD theory and practice. The interviews provided a more in-depth understanding of the practices used, and their context. The main findings from the interviews include: practitioners' attempts to start identifying NFRs early in the project, a lack of elicitation techniques aimed at NFRs only, and different choices about documentation techniques, including the additional techniques introduced to cope specifically with NFRs. Conclusions: It was not confirmed that requirements engineering activities related to NFRs are perceived by ASD practitioners as a problem, as they developed effective practices to deal with this issue. Moreover, our findings show that different approaches to NFRs can be used and give satisfactory results.

  • A review of recent advances in the single- and multi-degree-of-freedom ultrasonic piezoelectric motors
    • Roland Ryndzionek
    • Łukasz Sienkiewicz
    2021 Full text ULTRASONICS

    In this paper a comprehensive review of recent studies on the ultrasonic piezoelectric motors is presented. The analytical, numerical and experimental analysis. In further sections, classification methods of piezoelectric motors, survey criteria and three main groups of ultrasonic piezoelectric motors with examples have been presented and described. Finally, the conclusions and future research perspectives have been proposed.

  • A Review of Reduction Methods of Impact of Common-Mode Voltage on Electric Drives.
    • Marek Turzyński
    • Piotr Musznicki
    2021 Full text ENERGIES

    In this survey paper, typical solutions that focus on the reduction in negative effects resulting from the common-mode voltage influence in AC motor drive applications are re-examined. The critical effectiveness evaluation of the considered methods is based on experimental results of tests performed in a laboratory setup with an induction machine fed by an inverter. The capacity of a common-mode voltage level reduction and voltage gradient du/dt limitation is discussed to extend motor bearings’ lifetime and increase motor windings’ safety. The characteristic features of the described solutions are compared and demonstrated using laboratory results.

  • A Review of Traffic Analysis Attacks and Countermeasures in Mobile Agents' Networks
    • Rafał Leszczyna
    2021

    For traditional, message-based communication, traffic analysis has been already studied for over three decades and during that time various attacks have been recognised. As far as mobile agents’ networks are concerned only a few, specific-scope studies have been conducted. This leaves a gap that needs to be addressed as nowadays, in the era of Big Data, the Internet of Things, Smart Infrastructures and growing concerns for privacy, the subject gains particular importance. This paper presents the results of a literature study that aimed at identifying traffic analysing attacks and countermeasures in mobile agents’ networks. No limiting assumptions are made in regard to the complexity or size of agent networks. Also, various types of attackers’ configurations have been analysed and referred to each attack. The results enable building appropriate threat models for cybersecurity management or when designing new security solutions.

  • A review on application of artificial neural network (ANN) for performance and emission characteristics of diesel engine fueled with biodiesel-based fuels
    • Anh Tuan Hoang
    • Sandro Nižetić
    • Hwai Chyuan Ong
    • Wiesław Tarełko
    • Van Viet Pham
    • Tri Hieu Le
    • Minh Quang Chau
    • Xuan Phuong Nguyen
    2021 Sustainable Energy Technologies and Assessments

    Biodiesel has been emerging as a potential and promising biofuel for the strategy of reducing toxic emissions and improving engine performance. Computational methods aiming to offer numerical solutions were inevitable as a study methodology which was sometimes considered the only practical method. Artificial neural networks (ANN) were data-processing systems, which were used to tackle many issues in engineering and science, especially in some fields where there was a failure of the conventional modeling approaches. Thus, it was believed that the best choice was the development of a novel approach like the ANN model to anticipate engine performance and exhaust emissions with high accuracy. In this review paper, the structure and applicability of the ANN model were comprehensively evaluated. More importantly, the use of ANN with trained, tested, and validated data was introduced to determine the performance and emission characteristics of a diesel engine fueled with biodiesel-based fuel. In general, the ANN model could supply a relatively high determination coefficient as compared between predicted results and experimental data, showing that the ANN model could have a good ability to predict the engine behaviors with an accuracy higher than 95%.

  • A review on recent advances in the application of biosurfactants in wastewater treatment
    • Surya Teja Malkapuram
    • Vikrant Sharma
    • Sarang P. Gumfekar
    • Shirish H. Sonawane
    • Shriram Sonawane
    • Grzegorz Boczkaj
    • Murali Mohan Seepana
    2021 Full text Sustainable Energy Technologies and Assessments

    Microorganisms produce a variety of non-conventional surface-active molecules, known as biosurfactants. The biosurfactants find diverse applications in the oil industry, agriculture, emulsifiers, and wastewater treatment, to name a few. Since they are produced from microbes, advantages such as biodegradability, lower toxicity, and environmental compatibility can be leveraged compared to the chemical surfactants. Recently, biosurfactants found potential usability in treating wastewater generated from various domestic, industrial, and agricultural sources. The application of biosurfactants in wastewater treatment is mainly due to their excellent foaming ability, specific activity, and high selectivity under wide operation window of temperature, pH, and salinity. Wastewater treatment with use of low cost biosurfactant is one of the important suitable goal in treating the wastewater since biosurfactants can be produced from cheap material and cause less damage to the environment by replacing surfactants produced from petroleum crude. This review focuses on the recent developments in biosurfactant production using waste materials such as food and agricultural residues, industrial waste, and animal waste and their application in wastewater treatment processes such as contaminant degradation, oil–water separation, heavy metal removal, and effluent flotation. The characteristics of the biosurfactants produced from cheap materials are compared with that of synthetic surfactants. In fact, the characteristics of both types of surfactants are found to be similar. The ability of biosurfactants for pollution removal from wastewater is extensively reviewed and presented. Finally, the review also evaluates the economic feasibility of biosurfactant production on commercial scale and their industrial scale wastewater treatment application.

  • A selection of PID type controller settings via LQR approach for two-wheeled balancing robot
    • Krzysztof Laddach
    • Mateusz Czyżniewski
    • Rafał Łangowski
    2021 Full text

    The problem of PID type controller tuning has been addressed in this paper. In particular, a method of selection of PD settings based on the solution of linear–quadratic optimisation problem using the energy criterion has been investigated. Thus, the possibility of transforming optimal settings of the linear–quadratic regulator into the settings of the controller in the classical control system has been given. The presented methodology has been used during synthesis of control system for a two–wheeled balancing robot. Finally, the performance of the proposed control system has been validated by simulation in Matlab/Simulink environment with the use of a two–wheeled balancing robot model.

  • A Self-Adaptive Complex Root Tracing Algorithm for the Analysis of Propagation and Radiation Problem
    • Sebastian Dziedziewicz
    • Rafał Lech
    • Piotr Kowalczyk
    2021 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION

    An improved complex root tracing algorithm for radiation and propagation issues is proposed. The approach is based on a self-adaptive discretization of Cauchy’s argument principle for a C × R space and requires a reduced number of function calls in comparison to other procedures presented in the literature. A few different examples concerning propagation and radiation problems have been considered to verify the validity and efficiency of the proposed technique.

  • A sense of security and freedom in a residential environment
    • Antoni Taraszkiewicz
    • Karolina Taraszkiewicz
    2021 Full text World Transactions on Engineering and Technology Education

    The article is based on the results of a survey carried out among students of architecture faculties in several countries, which examined the students’ knowledge of shaping the housing environment in such a way as to enable them to fulfil two basic and, at the same time, seemingly mutually exclusive psychological needs of a person: a sense of security and a sense of freedom. In examining these issues, particular emphasis was placed on the possibility of creating such methods of architectural education that would make students - future engineers - aware of the necessity to understand the needs of the human psyche, and provide an opportunity to develop design skills to create a space that meets those needs. This kind of architectural education is part of the search for an answer to an important question today: how in the contemporary world, in a constantly transformed environment, can a person retain their own identity, find a place to live, find their own existential space?

  • A Series-Inclined-Slot-Fed Circularly Polarized Antenna for 5G 28-GHz Applications
    • Ubaid Ullah
    • Muath Al-hasan
    • Sławomir Kozieł
    • Ismail Mabrouk
    2021 Full text IEEE Antennas and Wireless Propagation Letters

    This letter presents the design of a single-point-fed, geometrically simple circularly polarized (CP) antenna for 28 GHz Ka-band applications. The proposed antenna is based on a straight microstrip line printed on one side and coupled with the nearly square patches through a 45-degree inclined V-shape slot aperture on the other side. In order to generate circular polarization, the fundamental radiating mode is degenerated at a slightly different frequency by aligning the patch edges parallel to each arm of the V-slot with orthogonal arms. This configuration yields a relatively small size (10 mm × 27.7 mm), wideband, and high-gain right-hand circularly polarized antenna operating at 28 GHz. The impedance bandwidth of the proposed antenna is from 27.2 GHz to 30.35 GHz and the 3 dB axial ratio (AR) bandwidth from 27.3 GHz to 29.7 GHz with excellent directional characteristics in the broadside direction. The peak realized gain is approximately 11.65 dBic. The performance characteristics in terms of the impedance matching, AR, gain and efficiency of the antenna for wearable applications are also investigated both numerically and experimentally. For practical applications, the small size of the structure allows for implementing the systems that consist of more than one antenna for mobility.

  • A ship domain-based model of collision risk for near-miss detection and Collision Alert Systems
    • Rafał Szłapczyński
    • Joanna Szłapczyńska
    2021 Full text RELIABILITY ENGINEERING & SYSTEM SAFETY

    The paper presents a new model of ship collision risk, which utilises a ship domain concept and the related domain-based collision risk parameters. An encounter is here described by five variables representing: degree of domain violation (DDV), relative speed of the two vessels, combination of the vessels’ courses, arena violations and encounter complexity. As for the first three variables, their values can be directly computed based on positions, courses and speeds of two vessels. The last two variables require decomposing a close quarters situation into phases. For this purpose the method utilizes a number of auxiliary parameters derived from the concept of ship domain: time of domain violation (TDV), time of domain exit (TDE), timespan of close quarters situation and vessels’ proximity, which is quantified based on the ship arena. The formulas and algorithms for determining all variables’ values are provided in detail. Once all the values are computed, the final collision risk assessment is made. Possible applications of the presented model include: AIS-based near-miss detection, Collision Alert Systems (CAS) and collision avoidance decision support systems (DSS). Case studies for those applications are provided, including examples of encounter classification and quantification of collision risk.

  • A Simple Neural Network for Collision Detection of Collaborative Robots
    • Michał Czubenko
    • Zdzisław Kowalczuk
    2021 Full text SENSORS

    Due to the epidemic threat, more and more companies decide to automate their production lines. Given the lack of adequate security or space, in most cases, such companies cannot use classic production robots. The solution to this problem is the use of collaborative robots (cobots). However, the required equipment (force sensors) or alternative methods of detecting a threat to humans are usually quite expensive. The article presents the practical aspect of collision detection with the use of a simple neural architecture. A virtual force and torque sensor, implemented as a neural network, may be useful in a team of collaborative robots. Four different approaches are compared in this article: auto-regressive (AR), recurrent neural network (RNN), convolutional long short-term memory (CNN-LSTM) and mixed convolutional LSTM network (MC-LSTM). These architectures are analyzed at different levels of input regression (motor current, position, speed, control velocity). This sensor was tested on the original CURA6 robot prototype (Cooperative Universal Robotic Assistant 6) by Intema. The test results indicate that the MC-LSTM architecture is the most effective with the regression level set at 12 samples (at 24 Hz). The mean absolute prediction error obtained by the MC-LSTM architecture was approximately 22 Nm. The conducted external test (72 different signals with collisions) shows that the presented architecture can be used as a collision detector. The MC-LSTM collision detection f1 score with the optimal threshold was 0.85. A well-developed virtual sensor based on such a network can be used to detect various types of collisions of cobot or other mobile or stationary systems operating on the basis of human-machine interaction.

  • A Simulation Model for Risk and Pricing Competition in the Retail Lending Market
    • Błażej Kochański
    2021 Full text FINANCE A UVER-CZECH JOURNAL OF ECONOMICS AND FINANCE

    We propose a simulation model of the retail lending market with two types of agents: borrowers searching for low interest rates and lenders competing through risk-based pricing. We show that individual banks observe adverse selection, even if every lender applies the same pricing strategy and a credit scoring model of comparable discrimination power. Additionally, the model justifies the reverse-S shape of the response rate curve. According to the model, the benefits of even small increases in the discrimination power of credit scoring are substantial. This effect is more pronounced if the number of offers checked by the applicants before making a decision increases. The simulations illustrate the trade-off between profitability, market share, and credit loss rates. The profit-maximising strategy is to set interest rates slightly lower than the competition; the excessive price reduction turns out to be counterproductive. At the same time, there exists a niche for higher yield players.

  • A Single-Carrier-Based Pulse-Width Modulation Template for Cascaded H-Bridge Multilevel Inverters
    • Charles Ikechukwu Odeh
    • Arkadiusz Lewicki
    • Marcin Morawiec
    2021 Full text IEEE Access

    Multiplicity of the triangular carrier signals is a criterion for the extension of sinusoidal pulsewidth modulation, SPWM, to a number of output voltage levels per phase-leg in cascaded H-bridge (CHB) multilevel inverter (MLI). Considering medium and high voltage applications where appreciable number of output voltage levels from CHB MLI is needed, commensurate high number of carrier signals in either classical level- or phase-shifted SPWM scheme for this inverter is inevitable. High-quality output waveforms from CHB MLI system demands precise synchronization of these multi-carrier signals. Sampling issues, memory constraints and computational delays pose difficulties in achieving this synchronization for real-time digital implementation. This study presents a PWM template for CHB MLI. The developed control concept generates adequate modulation templates for CHB inverter wherein a sinusoidal modulating waveform is modified to fit in a single triangular carrier signal range. These templates can be used on CHB inverter of any level with no further control modification. Nearly even distribution of switching pulses, equal sharing of the overall real power among the constituting power switches and enhanced output voltage quality were achieved with the proposed modulation. For a 3-phase, 7-level CHB, simulation and experimental results, for an R-L load, were presented.

  • A spline-based FE approach to modelling of high frequency dynamics of 1-D structures
    • Arkadiusz Żak
    • Wiktor Waszkowiak
    2021 Full text COMPUTERS & MATHEMATICS WITH APPLICATIONS

    In this paper a computational methodology leading to the development of a new class of FEs, based on the application of continuous and smooth approximation polynomials, being splines, has been presented. Application of the splines as appropriately defined piecewise elemental shape functions led the authors to the formulation of a new approach for FEM, named as spFEM, where contrary to the well-known NURBS approach, the boundaries of spFEs are well-defined, exactly as it is in the case of the traditional FEM. The current approach has been computationally verified by the authors it terms of high frequency dynamics including such problems as: spectra of natural frequencies, modes of natural vibrations as well as wave propagation problems, especially in the aspect of high frequency responses, all in the case of selected problems involving one- and two-mode theories of 1-D structural elements. The applicability of the proposed approach has been evaluated and compared, in terms of calculated dynamic responses, with the results obtained by the use of well-established FEM approaches: classical FEM as well as TD-SFEM. In all cases investigated by the authors the proposed spFEM approach turned out to be the most accurate approach, free from the main drawback of the other tested FEM approaches thanks to the class of differentiability of approximation polynomials, which guarantees the absence of frequency band gaps in calculated spectra of natural frequencies. A direct consequence of this feature of the proposed approach is that a larger part of the calculated spectra of natural frequency, the same as modes of natural vibrations, can effectively be used for more accurate calculations of dynamic reposes even in the case of multi-mode theories. This in contrast to the other tested FEM approaches.

  • A study about daylighting knowledge and education in Europe. Results from the first phase of the DAYKE project
    • Federica Giuliani
    • Natalia Sokół
    • Valerio R.M. Lo Verso
    • Raquel Viula
    • Federica Caffaro
    • Bernard Paule
    • Aicha Diakite
    • Yannick Sutter
    2021 Full text Architectural Science Review

    This paper presents selected results from the first stage of DAYKE (Daylight Knowledge in Europe), a 3- phase project that investigates the knowledge on daylighting in buildings among architecture students and practitioners across Europe. Subjective judgements from 561 students from 8 architecture universities in the EU, collected through two surveys in 2018. The key findings are: (i) the spatial distribution of comfort and mood in the classrooms varied depending on sky conditions and distance from windows; (ii) the average daylight factor DFm showed a good agreement with subjective judgements on the amount of daylight in a space; (iii) experts and non-experts provided similar judgements on the perception of a daylit environment; (iv) a general lack of knowledge about daylighting metrics, regulations, assessment tools and software was highlighted. Furthermore a difficulty in implementing daylighting into the design practice is also identified.

  • A study of jet impingement cooling enhancement by concave and convex heat sink shape modifications
    • Marcin Froissart
    • Paweł Ziółkowski
    • Janusz Badur
    2021 Full text E3S Web of Conferences

    The rising demand for efficient cooling technologies is a strong driver of extensive research in this area. This trend is particularly strong in turbines and microprocessors technology. Presented study is focused on the jet impingement cooling concept, which is used in various configurations for many years. The potential of the heat sink shape modification is not yet fully explored. Available literature suggests that average Nusselt number can be improved by more than 10% by adding conical shape in the stagnation region. This refers to the axisymmetric case where cold-water jet impinges the surface of heated aluminium. Presented results are based on 2D axisymmetric thermal-FSI (Fluid-Solid Interaction) model, which was validated against the experiment. The objective of the presented analysis is to determine the correlation between cooling effectiveness (Nusselt number) and chosen examples of concave and convex shapes located in the jet stagnation area.

  • A study on diagnosing both isotropic and orthotropic, intentionally damaged laminates
    • Khadijeh Askaripour
    • Arkadiusz Żak
    2021 Nondestructive Testing and Evaluation

    Being the most detrimental mode in laminated structures, delamination initially degrades local structural strength, and lastly causes global structural failure, thus necessitating delamination identification at its incipient stages. For identification purposes, a comprehensive numerical and experimental study on delamination within both the laminated isotropic acrylic-glass and orthotropic epoxyglass plates is presented. As the first step, frequency variations in the acrylic-glass plate induced by different-sized delamination are examined at varying the in-plane or out-of-plane location as well as boundary conditions of delamination. Tiny delamination is identified by the use of processed signals of Lamb wave simulated by spectral finite element (SFE) technique in the next step when noticing the delamination-induced changes of frequency to be inefficient for detection purposes. While utilising absorbing layers with the obtained mechanical properties along the axis of symmetry, a quarter of the plate in the SFE domain is modelled. The study is concluded with finding the accurate location and shape of small delamination using A0 or S0 modes. The preference of A0 mode for the delamination identification compared to S0 mode is indicated. Finally, for verification purposes of Lamb wave patterns in real-life applications, a composite epoxy-glass plate is experimentally investigated via laser Doppler vibrometer (LDV).

  • A Survey of Fast-Recovery Mechanisms in Packet-Switched Networks
    • Marco Chiesa
    • Andrzej Kamisinski
    • Jacek Rak
    • Gabor Retvari
    • Stefan Schmid
    2021 Full text IEEE Communications Surveys and Tutorials

    In order to meet their stringent dependability requirements, most modern packet-switched communication networks support fast-recovery mechanisms in the data plane. While reactions to failures in the data plane can be significantly faster compared to control plane mechanisms, implementing fast recovery in the data plane is challenging, and has recently received much attention in the literature. This survey presents a systematic, tutorial-like overview of packet-based fast-recovery mechanisms in the data plane, focusing on concepts but structured around different networking technologies, from traditional link-layer and IP-based mechanisms, over BGP and MPLS to emerging software-defined networks and programmable data planes. We examine the evolution of fast-recovery standards and mechanisms over time, and identify and discuss the fundamental principles and algorithms underlying different mechanisms. We then present a taxonomy of the state of the art, summarize the main lessons learned, and propose a few concrete future directions.

  • A Systematic Literature Review on Implementing Non-functional Requirements in Agile Software Development: Issues and Facilitating Practices
    • Aleksander Jarzębowicz
    • Paweł Weichbroth
    2021 Full text Lecture Notes in Business Information Processing

    Agile Software Development methods have become a widespread approach used by the software industry. Non-functional requirements (NFRs) are often reported to be a problematic issue for such methods. We aimed to identify (within the context of Agile projects): (1) the issues (challenges and problems) reported as affecting the implementation of NFRs; and (2) practices that facilitate the successful implementation of NFRs. We conducted a systematic literature review and processed its results to obtain a comprehensive summary. We were able to present two lists, dedicated to issues and practices, respectively. Most items from both lists, but not all, are related to the requirements engineering area. We found out that the issues reported are mostly related to the common themes of: NFR documentation techniques, NFR traceability, elicitation and communication activities. The facilitating practices mostly cover similar topics and the recommendation is to start focusing on NFRs early in the project.

  • A technique of experiment aided virtual prototyping to obtain the best spindle speed during face milling of large-size structures
    • Krzysztof Kaliński
    • Marek Galewski
    • Michał Mazur
    • Natalia Morawska
    2021 Full text MECCANICA

    The paper presents an original method concerning vibration suppression problem during milling of large-size and geometrically complicated workpieces with the use of novel way of selecting the spindle speed. This consists in repetitive simulations of the cutting process for subsequent values of the spindle speed, until the best vibration state of the workpiece is reached. An appropriate method of obtaining a computational model, called a modal approach, consists in identifying the parameters of the workpiece model created using the Finite Element Method (FEM). Thanks to the results of the identification of the modal subsystem obtained by the Experimental Modal Analysis (EMA) method, it can be stated that the parameters obtained from the experiment and delivered from the computational model have been correctly determined and constitute reliable process data for the simulation tests. The Root Mean Square (RMS) values of time domain displacements are evaluated. The efficiency of the proposed approach is evidenced by chosen technique of mechatronic design, called Experiment Aided Virtual Prototyping (EAVP). The proposed method is verified on the basis of the results of the experimental research of the relevant milling process.

  • A Universal Gains Selection Method for Speed Observers of Induction Machine
    • Daniel Wachowiak
    2021 Full text ENERGIES

    Properties of state observers depend on proper gains selection. Each method of state estimation may require the implementation of specific techniques of finding those gains. The aim of this study is to propose a universal method of automatic gains selection and perform its verification on an induction machine speed observer. The method utilizes a genetic algorithm with fitness function which is directly based on the impulse response of the observer. System identification using least-squares estimation is implemented to determine the dynamic properties of the observer based on the estimation error signal. The influence of sampling time as well as signal length on the system identification has been studied. The results of gains selection using the proposed method have been compared with results obtained using the approach based on the placement of the poles of linearized estimation error equations. The introduced method delivers results comparable with analytical methods and does not require prior preparation specific to the implemented speed observer, such as linearization.

  • A variational approach of homogenization of piezoelectric composites towards piezoelectric and flexoelectric effective media
    • Nagham Mawassy
    • Hilal Reda
    • Jean-François Ganghoffer
    • Victor Eremeev
    • Hassan Lakiss
    2021 Full text INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE

    The effective piezoelectric properties of heterogeneous materials are evaluated in the context of periodic homogenization, whereby a variational formulation is developed, articulated with the extended Hill macrohomogeneity condition. The entire set of homogenized piezoelectric moduli is obtained as the volumetric averages of the microscopic properties of the individual constituents weighted by the displacement and polarization localization operators. This framework is extended in a second part of the paper to the computation of the flexoelectric effective properties, thereby accounting for higher gradient effects that may be induced by a strong contrast of properties of the composite constituents. The effective properties of inclusion-based composites are evaluated numerically as an illustration of the general homogenization theory and the respective effect of the volume fraction and relative tensile modulus of the reinforcement is assessed numerically.

  • A Wideband Channel Model for Body Area Networks in Circular Metallic Indoor Environments
    • Filipe D. Cardoso
    • Manuel M. Ferreira
    • Sławomir Ambroziak
    • Luis M. Correia
    2021 Full text IEEE Access

    In this paper, the wideband characterization of the propagation channel in circular metallic indoor environments is addressed, regarding Body Area Networks and 5G small cells, an analytical model for the dependence of the mean delay and the average delay spread on the circle radius, the working frequency and the distance between the transmitter and the receiver being proposed. The derivation of the model is initially done analytically, based on optical physics, after which simulation results allow to obtain the values of the coefficients. The simulator was previously assessed with measurements at 2.45 GHz in a passenger ferry room with a circular shape. For a random positioning of the transmitter and the receiver, and a given distance between them, it is observed that the mean delay and the delay spread increase linearly with the radius; furthermore, the mean delay increases quadratically with the distance, while the delay spread has a concave parabolic behavior, with the maximum being at a distance equal to the radius. In a practical case, regarding the positioning of an Access Point inside the room, it is recommended that it is done at the circle center, in order to reduce delay spread.

  • A wireless network for off-shore marine research
    • Krzysztof Gierłowski
    • Michał Hoeft
    • Marcin Wichorowski
    2021 Bollettino di Geofisica Teorica ed Applicata

    This paper presents functionality, the most important technology developments and potential use cases of digital communication system, developed to facilitate selected tasks commonly required during off-shore operations and marine research, including: broadband information sharing between platforms isolated from an on-shore communication infrastructure, acquisition of large data-sets from variety of off-shore data sources (e.g. fleet of drones) as well as remote access and control to the research infrastructure exploited in environment with limited communication between neighboring devices.

  • Abilities, Motivations, and Opportunities of Furloughed Employees in the Context of Covid-19: Preliminary Evidence From the UK
    • Joanna Szulc
    • Rachael Smith
    2021 Full text Frontiers in Psychology

    The Covid-19 global pandemic is a crisis like no other, forcing governments to implement prolonged national lockdowns in an effort to limit the spread of the disease. As organizations aim to adapt and remain operational, employers can suspend or reduce work activity for events related to Covid-19 and claim government support to subsidize employee wages. In this way, some employees are placed on furlough (i.e., temporary unemployment) as opposed to being made redundant. While the impact of such schemes on global economy attracted much attention, their micro-level impact on individual employees is still unknown. Building on the ability-motivation-opportunity (AMO) framework, this pilot study explores how employees' perceptions of abilities, motivation, and opportunities are affected as a result of furlough. Rapid ethnography including interviews, observations, and document analysis in a British organization provided insights into the perceptions and experiences of employees put on furlough and highlighted that all three elements of AMO are affected by the current situation, either positively or negatively. We identify theoretical contributions and suggest a number of AMO enhancing practices in the context of furlough.

  • Accelerated Gradient-Based Optimization of Antenna Structures Using Multi-Fidelity Simulations and Convergence-Based Model Management Scheme
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2021 Full text IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION

    The importance of numerical optimization has been steadily growing in the design of contemporary antenna structures. The primary reason is the increasing complexity of antenna topologies, [ a typically large number of adjustable parameters that have to be simultaneously tuned. Design closure is no longer possible using traditional methods, including theoretical models or supervised parameter sweeping. To ensure reliability, optimization is normally carried out at the level of full-wave electromagnetic (EM) simulations, which incurs major computational expenses. The issue can be alleviated using a variety of methods such as the incorporation of adjoint sensitivities, sparse sensitivity updates (for local optimization), or the employment of surrogate modeling methods (in the context of global search). Another possibility is utilization of variable-fidelity simulation models, which, in practice, is most often restricted to two levels (coarse/fine or low-/high-fidelity models), and accompanied by appropriate low-fidelity model correction (e.g., space mapping). This paper proposes an accelerated version of a trust-region gradient-based procedure, which involves simulation model management by continuous adjustment of EM analysis fidelity throughout the optimization process. Decision making process is based on the convergence status of the algorithm. The initial stages of the optimization run are executed using the coarsest discretization of the structure at hand with the model being gradually refined towards the end of the process. This enables considerable computational savings without degrading the quality of the final design. The presented approach has been comprehensively validated using a benchmark set of four broadband antennas and compared to the reference trust-region procedure and two state-of-the-art accelerated algorithms. The average computational savings are almost sixty percent as compared to the reference.

  • Accelerated large scale test set-up design in natural corrosion marine environment
    • Krzysztof Wołoszyk
    • Yordan Garbatov
    2021

    The standards for conducting small-scale specimen tests are well developed, but there is a lack of direct guidelines for conducting corrosion tests for large-scale specimens. The objective here is to develop a methodology which may be used in designing an accelerated corrosion test of large-scale structural components subjected to a natural corrosion marine environment. Different factors influencing corrosion degradation of steel structures are analysed, including salinity and pH of the water, water velocity, oxygen content etc. The most important governing factors of corrosion degradation are identified, and the process of corrosion testing is defined in order to produce accelerated corrosion degradation in relatively short interval of time, developing a natural corrosion degradation mechanism, leading to irregular random corroded surfaces and material properties changes. Existing commercial testing equipment, that can be employed in creating accelerated corrosion conditions for testing large scale specimens, are investigated and the most efficient salt corrosion testing tank is identified. Several features of the corrosion test set-up are discussed.

  • Accumulation of volatile constituents in agar and bioreactor shoot cultures of Verbena officinalis L.
    • Adam Kokotkiewicz
    • Bożena Zabiegała
    • Pawel Kubica
    • Agnieszka Szopa
    • Adam Bucinski
    • Halina Ekiert
    • Maria Luczkiewicz
    2021 PLANT CELL TISSUE AND ORGAN CULTURE

    In vitro shoot cultures of common vervain (Verbena officinalis L., Verbenaceae) were established and evaluated for essential oil content. The shoots were maintained as stationary microshoot culture, grown on Schenk–Hildebrandt medium supplemented with 9.84 µM of 2-isopentenyladenine and 1.0 µM of thidiazuron. The shoots were further adapted to grow in two temporary immersion bioreactors (RITA and Plantform), using Schenk–Hildebrandt medium supplemented with 4.92 µM indole-3-butyric acid. The best growth, in terms of dry weight production, was recorded for agar culture (0.73 g l−1 day−1), followed by 35 days (day) Plantform (0.53 g l−1 day−1), 35 days RITA (0.42 g l−1 day−1) and 56 days Plantform culture (0.29 g l−1 day−1). The volatile fractions were obtained by simultaneous hydrodistillation-extraction of the plant materials using Likens–Nickerson apparatus. Aerial parts of V. officinalis intact plant and 56 d Plantform culture had the highest essential oil content (8.1 g kg−1) whereas the stationary agar culture excelled in essential oil productivity (5.0 mg l−1 day−1). The volatile oils isolated from in vitro shoots contained 1-octen-3-ol, benzyl alcohol, phenethyl alcohol, coumaran and hexadecenoic acid as major constituents. 1-Octen-3-ol was the predominant (> 50%) constituent of 35 day shoot cultures maintained in temporary immersion bioreactors whereas coumaran (19%) and hexadecanoid acid (21%) prevailed in stationary microshoot culture. The volatile fraction obtained from aerial parts of V. officinalis intact plant was composed mainly of hexadecanoic acid (> 20%), linalool (> 8%), anethole (> 5%) and carvone (> 3%).

  • Accuracy of Pretreatment Ultrasonography Assessment of Intra-Abdominal Spread in Epithelial Ovarian Cancer: A Prospective Study
    • Agnieszka Tomasińska
    • Maciej Stukan
    • Michał Badocha
    • Aleksandra Myszewska
    2021 Full text Diagnostics

    The aim of this study was to test the accuracy of ultrasonography performed by gynecological oncologists for the preoperative assessment of epithelial ovarian cancer (EOC) spread in the pelvis and abdominal cavity. A prospective, observational cohort study was performed at a single tertiary cancer care unit. Patients with suspected EOC were recruited and underwent comprehensive transvaginal and abdominal ultrasonography performed by a gynecological oncologist. Sixteen intra-abdominal localizations and parameters were assessed using ultrasonography and compared with surgical-pathological status (reference standard). Sensitivity, specificity, positive and negative predictive values, and overall accuracy were calculated. Differences were analyzed using Fisher’s exact and chi-square tests. Ultimately, we included 132 patients (median age 62 years), of whom 67% were in stage IIIC–IVB and 72% had serous cancer. Overall prediction accuracies for the involvement of the omentum, small bowel mesentery root, and frozen pelvis, and detecting ascites were >90%. Detecting the involvement of the pelvis peritoneum, liver and spleen hilum, and rectosigmoid colon, and predictions of disease stage and residual disease had overall accuracies of 80–90%. The lowest accuracy was for involvement of the abdominal peritoneum (69%) and diaphragm peritoneum (right 71%; left 75%) and surgical complexity prediction (77%). Stratification of results by presence or absence of ascites revealed significantly higher specificity of ultrasonography (clinically meaningful) for assessments of the abdominal/pelvic peritoneum, spleen hilum, and rectum wall, if there were ascites. A gynecological oncologist, experienced in surgery and sonology, performing comprehensive ultrasonography on patients with EOC can accurately detect intraperitoneal lesions and recognize critical disease manifestations and predict stage, surgical complexity, and residual disease, which allow accurate qualification of patients for primary debulking surgery or neoadjuvant chemotherapy.

  • Accurate Modeling of Frequency Selective Surfaces Using Fully-Connected Regression Model with Automated Architecture Determination and Parameter Selection Based on Bayesian Optimization
    • Nurullah Calik
    • Mehmet Belen
    • Peyman Mahouti
    • Sławomir Kozieł
    2021 Full text IEEE Access

    Surrogate modeling has become an important tool in the design of high-frequency structures. Although full-wave electromagnetic (EM) simulation tools provide an accurate account for the circuit characteristics and performance, they entail considerable computational expenditures. Replacing EM analysis by fast surrogates provides a way to accelerate the design procedures. Unfortunately, modeling of microwave passives is a challenging task due to their highly-nonlinear outputs. Frequency selective surfaces (FSSs) constitute a representative example with their multi-resonant reflection and transmission responses that need to be represented over broad frequency ranges. Deep neural networks (DNNs) seem to be the promising techniques for handling such cases. However, a serious practical issue associated with their employment is an appropriate selection of the model parameters, including its architecture. A common practice is experience-driven setup, heavily based on trial and error, which does not guarantee the optimum model determination and may lead to multiple problems such as poor generalization or high variance of the model predictive power with respect to the training data set selection. This paper proposes a novel modeling framework, referred to as a fully-connected regression model (FCRM), where the crucial role is played by Bayesian Optimization (BO), incorporated to determine the DNN-based model setup, including both its architecture and the hyperparameter values, in a fully automated manner. For validation, FCRM is applied to construct the model of a Minkowski Fractal-Based FSS. The efficacy of the methodology is demonstrated through comparisons with several benchmark techniques, including the DNN surrogates established using the traditional methods as well as conventional regression models. The numerical results indicate that FCRM exhibits considerably improved prediction power and reduced sensitivity to the training sample assignment.

  • Achieving Efficient and Stable Deammonification at Low Temperatures—Experimental and Modeling Studies
    • Hussein Al-Hazmi
    • Xi Lu
    • Dominika Grubba
    • Joanna Majtacz
    • Przemysław Kowal
    • Jacek Mąkinia
    2021 Full text ENERGIES

    The short-term effects of temperature on deammonification sludge were evaluated in a laboratory-scale sequencing batch reactor (SBR). Mathematical modeling was used for further evaluations of different intermittent aeration strategies for achieving high and stable deammonification performance at decreasing temperatures. As for the biomass cultivated at high temperatures (e.g., 30 C), a higher temperature dependency (the adjusted Arrhenius coefficient for 11–17 C = 1.71 vs. for 17–30 C = 1.12) on the specific anammox growth rates was found at lower temperatures (11–17 C) in comparison with higher temperatures (17–30 C). Further evaluations of recovering the nitrogen removal efficiency at decreasing temperatures with the mathematical model by modifying the intermittent aeration strategies (aeration frequency (F) and the ratio (R) between non-aerated (non-aer) phase and aerated (aer) phase durations) indicated that intermittent aeration with a prolonged non-aerated phase (e.g., R 4 regardless of F value) would help to maintain high and stable deammonification performance (~80%) at decreasing temperatures (14–22 C). Extending the non-aerated phases (increasing R) and reducing the frequency (F) of off/on phase changes have a positive effect on increasing energy savings, leading to increasing interest in this method.

  • Acid Rider. Idea „komunizmu kwasowego” Marka Fishera a doświadczenie zewnętrzności
    • Andrzej Karalus
    2021 Full text Praktyka Teoretyczna

    Acid communism pozostaje intrygującym wstępem Marka Fishera do planowanej przezeń historycznej rekonstrukcji radykalnych projektów politycznych wyrosłych na gruncie kultury psychodelicznej. Idea ta nie narodziła się w próżni, lecz stanowi konsekwencję jego poszukiwań teoretycznych. Artykuł próbuje osadzić koncepcję „komunizmu kwasowego” w szerszym kontekście, skupiając się na refleksji poświęconej doświadczeniu psychodelicznemu jako kontakcie z Zewnętrzem. Twierdzę, że istnieje zbieżność między koncepcją komunizmu kwasowego a zagadnieniami poruszanym przez Fishera w książce The Weird And The Eerie, gdzie analizuje potencjalnie transformujący szok zetknięcia z tym, co radykalnie Inne. Omówię przy tym krótko dwa fenomeny muzyczno-kulturowe, które zaistniały już po epoce psychodelii lat sześćdziesiątych. Posłużą one za egzemplifikacje trybów weird oraz eerie, obietnic przyszłości pokapitalistycznej, które nie znalazły politycznej reprezentacji i osunęły się na poziom widma niezrealizowanej przyszłości modernizmu. W końcowej części artykułu spróbuję pokazać jak zagadnienie komunizmu kwasowego wiąże się z kwestią pragnienia postkapitalistycznego oraz z Fisherowską wersją futuro-akceleracjonizmu.

  • Acoustic Detector of Road Vehicles Based on Sound Intensity
    • Grzegorz Szwoch
    • Józef Kotus
    2021 Full text SENSORS

    A method of detecting and counting road vehicles using an acoustic sensor placed by the road is presented. The sensor measures sound intensity in two directions: parallel and perpendicular to the road. The sound intensity analysis performs acoustic event detection. A normalized position of the sound source is tracked and used to determine if the detected event is related to a moving vehicle and to establish the direction of movement. The algorithm was tested on a continuous 24-h recording made in real-world conditions. The overall results were: recall 0.95, precision 0.95, F-score 0.95. In the analysis of one-hour slots, the worst results obtained in dense traffic were: recall 0.9, precision 0.93, F-score 0.91. The proposed method is intended for application in a network of traffic monitoring sensors, such as a smart city system. Its advantages include using a small, low cost and passive sensor, low algorithm complexity, and satisfactory detection accuracy

  • Acoustic Sensing Analytics Applied to Speech in Reverberation Conditions
    • Piotr Odya
    • Józef Kotus
    • Adam Kurowski
    • Bożena Kostek
    2021 Full text SENSORS

    The paper aims to discuss a case study of sensing analytics and technology in acoustics when applied to reverberation conditions. Reverberation is one of the issues that makes speech in indoor spaces challenging to understand. This problem is particularly critical in large spaces with few absorbing or diffusing surfaces. One of the natural remedies to improve speech intelligibility in such conditions may be achieved through speaking slowly. It is possible to use algorithms that reduce the rate of speech (RoS) in real time. Therefore, the study aims to find recommended values of RoS in the context of STI (speech transmission index) in different acoustic environments. In the experiments, speech intelligibility for six impulse responses recorded in spaces with different STIs is investigated using a sentence test (for the Polish language). Fifteen subjects with normal hearing participated in these tests. The results of the analytical analysis enabled us to propose a curve specifying the maximum RoS values translating into understandable speech under given acoustic conditions. This curve can be used in speech processing control technology as well as compressive reverse acoustic sensing.

  • Action Plan “Women”
    • Marzena Grzesiak
    • Anita Richert-Kaźmierska
    2021

    Employees of a company are not the first alternative coming into one’s mind when searching suitable successor for the business. Those belonging to the company’s management group are in many cases asked for their interest in being a successor, but the lower level an employee is in the hierarchy, the less probably he/she is inquired of his/her interest in becoming a successor. The contemporary entrepreneur may have had conflicts with employees, he may underestimate their capacities or there might be suspects concerning their loyalty to the company. On the other hand, it can be also difficult for an employee to express his interests in acquiring the business. The social pressure against the colleague wishing to start a trip across the classes, i.e. from worker to capitalist, may be, epending to the country, area and culture, crushing. An employee’s own family may be very critic against plans like that too. Nevertheless, many aspects are in favor of employees as considerable successors. In this chapter, these will be further discussed.

  • Activation of endogenous regenerative potential in mammals using epigenetic inhibitor zebularine
    • Piotr Sass
    2021

    In this work, a nucleoside inhibitor of DNA methyltransferases, zebularine, was investigated as a wound healing and regeneration promoting agent. It was found that a high dose of intraperitoneally delivered zebularine improved punch wound closure in the ear pinna in mice. Both cytidine, a zebularine analogue, and uridine, a zebularine metabolite, did not promote ear pinna hole closure. The effect of zebularine on ear pinna healing was dose-dependent. Further experiments showed that zebularine administration should be carried out shortly after the injury as several-day delays resulted in decreased effectiveness. Transcriptional activity of genes related to stem cell development and maintenance and cell cycle progression regulation was evaluated in the ear pinna tissues regenerating in response to zebularine treatment. Two of the crucial cell pluripotency genes, Nanog and Sox2, were remarkably induced in zebularine-treated ear pinnae on day 7 after injury. Also, the Cdkn2a gene encoding an inhibitor of a cell cycle progression was significantly upregulated in zebularine-treated pinnae. These findings suggest that zebularine enhances wound repair by activating genes that are silenced in adult tissues in normal conditions. Preliminary trials to translate the zebularine regenerative therapy to other injury models were performed. Topically delivered zebularine moderately accelerated dorsal skin wound healing in mice and positively affected the tissue architecture in the restored skin. This observation suggests that zebularine might drive skin repair into a regenerative response. Besides, a pilot experiment was carried out to evaluate the zebularine treatment effect on sciatic nerve healing following a crush-injury. To my knowledge, the zebularine-induced ear pinna regeneration is the first example of regenerating a complex tissue by use of an epigenetic inhibitor in vivo. These findings indicate that epigenetic modulation might become an essential step in regenerative therapies.

  • Active Annotation in Evaluating the Credibility of Web-Based Medical Information: Guidelines for Creating Training Data Sets for Machine Learning
    • Aleksandra Nabożny
    • Bartłomiej Balcerzak
    • Adam Wierzbicki
    • Mikołaj Morzy
    • Małgorzata Chlabicz
    2021 Full text JMIR Medical Informatics

    Methods Results Discussion References Abbreviations Copyright Abstract Background: The spread of false medical information on the web is rapidly accelerating. Establishing the credibility of web-based medical information has become a pressing necessity. Machine learning offers a solution that, when properly deployed, can be an effective tool in fighting medical misinformation on the web. Objective: The aim of this study is to present a comprehensive framework for designing and curating machine learning training data sets for web-based medical information credibility assessment. We show how to construct the annotation process. Our main objective is to support researchers from the medical and computer science communities. We offer guidelines on the preparation of data sets for machine learning models that can fight medical misinformation. Methods: We begin by providing the annotation protocol for medical experts involved in medical sentence credibility evaluation. The protocol is based on a qualitative study of our experimental data. To address the problem of insufficient initial labels, we propose a preprocessing pipeline for the batch of sentences to be assessed. It consists of representation learning, clustering, and reranking. We call this process active annotation. Results: We collected more than 10,000 annotations of statements related to selected medical subjects (psychiatry, cholesterol, autism, antibiotics, vaccines, steroids, birth methods, and food allergy testing) for less than US $7000 by employing 9 highly qualified annotators (certified medical professionals), and we release this data set to the general public. We developed an active annotation framework for more efficient annotation of noncredible medical statements. The application of qualitative analysis resulted in a better annotation protocol for our future efforts in data set creation. Conclusions: The results of the qualitative analysis support our claims of the efficacy of the presented method.

  • Active Suppression of Nonstationary Narrowband Acoustic Disturbances
    • Maciej Niedźwiecki
    • Michał Meller
    2021 Full text

    In this chapter, a new approach to active narrowband noise control is presented. Narrowband acoustic noise may be generated, among others, by rotating parts of electro-mechanical devices, such as motors, turbines, compressors, or fans. Active noise control involves the generation of “antinoise”, i.e., the generation of a sound that has the same amplitude, but the opposite phase, as the unwanted noise, which causes them to interfere destructively, rather than constructively. In the range of low frequencies (below 1 kHz), the active approach is more effective than passive methods that employ dampers, barriers, absorbers, and other forms of acoustic isolation.