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Gdańsk University of Technology

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Publications from the year 2021

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  • Real-time monitoring of volatiles and particles emitted from thermoplastic filaments during 3D printing
    • Wojciech Wojnowski
    2021

    Presentation on the use of instrumental analytical techniques for the assessment of emission of volatiles and particulates during fdm 3d printing.

  • Real-time monitoring of volatiles and particles emitted from thermoplastic filaments during 3D printing
    • Wojciech Wojnowski
    • Renata Marcinkowska
    • Bożena Zabiegała
    2021 Full text IOP Conference Series: Materials Science and Engineering

    The proliferation of consumer-grade three-dimensional (3D) printers using fused deposition, also known as fused filament fabrication, has given rise to concerns over the exposure of users to potentially harmful substances. Thermoplastic filaments made of different polymers are extruded through a heated printer nozzle and deposited layer by layer on a build platform to form the printed object. This process leads to the emission of both particles and gases, in particular volatile organic compounds (VOCs). While the emission of airborne particulate matter during 3D-printing has been relatively well researched [1], this is not the case with the monitoring of the associated emission of VOCs, and so we are far from understanding the emission profile of 3D-printers as a whole. The main reason for that is the difficulty with sampling the emitted volatiles with sufficient time resolution to investigate e.g. the effect of rapid heating of the nozzle, and so the available data mostly describes either the total emission of particular VOCs during printing, or the time-resolved emission of total VOCs, without the determination of particular compounds [2,3]. In order to bridge this gap, we have previously demonstrated that proton transfer reaction mass spectrometry (PTR-MS) can be used to monitor the emission of volatiles during 3D-printing in real-time, both qualitatively and quantitatively [4]. Here, we propose to combine this approach with the concurrent real-time measurement of the corresponding emission of particles to obtain a more detailed understanding of the profile of pollutants generated during 3D-printing and the factors which determine this process.

  • Recent Advances in Accelerated Multi-Objective Design of High-Frequency Structures using Knowledge-Based Constrained Modeling Approach
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2021 KNOWLEDGE-BASED SYSTEMS

    Design automation, including reliable optimization of engineering systems, is of paramount importance for both academia and industry. This includes the design of high-frequency structures (antennas, microwave circuits, integrated photonic components), where the appropriate adjustment of geometry and material parameters is crucial to meet stringent performance requirements dictated by practical applications. Realistic design has to account for multiple objectives, which are often conflicting. Identification of available trade-offs (e.g., electrical/field properties vs. physical size and cost), otherwise essential from industry standpoint, requires multi-objective optimization. It is a computationally expensive endeavor as in most cases—for the sake of accuracy—the system evaluation has to be carried out using full-wave electromagnetic (EM) analysis. Attempting to solve EM-driven multi-objective (MO) tasks directly using population-based nature-inspired techniques may be prohibitive in terms of cost. Employing surrogate modeling techniques can lead to mitigation of the cost issue; however, construction of fast replacement models over broad ranges of the system parameters is expensive by itself, especially in higher-dimensional spaces. Recently, several approaches involving knowledge-based surrogate modeling approach have been proposed with the metamodels constructed over small regions of the parameter space containing the Pareto front. The latter are approximated using the sets of pre-optimized reference designs and permit a dramatic reduction of the number of training points required to set up a reliable surrogate, thus reducing the overall cost of the MO process. This paper reviews the recent advancements in these methodologies, and demonstrates the benefits of domain confinement using the various techniques such as reference design triangulation, nested kriging, and modeling with explicit dimensionality reduction using spectral analysis of the reference set. Demonstration examples of multi-objective design of antenna and miniaturized microwave components are provided as well.

  • Recent Advances in Loop Heat Pipes with Flat Evaporator
    • Paweł Szymański
    • Richard Law
    • Ryan McGlen
    • David Reay
    2021 Full text ENTROPY

    The focus of this review is to present the current advances in Loop Heat Pipes (LHP) with flat evaporators, which address the current challenges to the wide implementation of the technology. A recent advance in LHP is the design of flat-shaped evaporators, which is better suited to the geometry of discretely mounted electronics components (microprocessors) and therefore negate the need for an additional transfer surface (saddle) between component and evaporator. However, various challenges exist in the implementation of flat-evaporator, including (1) deformation of the evaporator due to high internal pressure and uneven stress distribution in the non-circular casing; (2) heat leak from evaporator heating zone and sidewall into the compensation chamber; (3) poor performance at start-up; (4) reverse flow through the wick; or (5) difficulties in sealing, and hence frequent leakage. This paper presents and reviews state-of-the-art LHP technologies; this includes an (a) review of novel manufacturing methods; (b) LHP evaporator designs; (c) working fluids; and (d) construction materials. The work presents solutions that are used to develop or improve the LHP construction, overall thermal performance, heat transfer distance, start-up time (especially at low heat loads), manufacturing cost, weight, possibilities of miniaturization and how they affect the solution on the above-presented problems and challenges in flat shape LHP development to take advantage in the passive cooling systems for electronic devices in multiple applications.

  • Recent advances on spinel-based protective coatings for solid oxide cell metallic interconnects produced by electrophoretic deposition
    • E Zanchi
    • A Sabato
    • Sebastian Molin
    • Grzegorz Cempura
    • A Boccaccini
    • F Smeacetto
    2021 MATERIALS LETTERS

    The application of ceramic protective coatings to the metallic interconnects in solid oxide cells (SOCs) is a viable and effective method to limit interconnect degradation issues. This featured letter provides a critical overview of the main outcomes of current research on the use of the electrophoretic deposition (EPD) technique to produce protective coatings for SOC metallic interconnects, specifically focusing on different approaches to stabilise spinel-based suspensions, as well as the possible sintering procedures. The protective properties of EPD coatings are reviewed and discussed in terms of oxidation kinetics and area specific resistance evaluation.

  • Recent advances on the removal of phosphorus in aquatic plant-based systems
    • Shahabaldin Rezania
    • Hesam Kamyab
    • Parveen Fatemeh Rupani
    • Junboum Park
    • Nicole Nawrot
    • Ewa Wojciechowska
    • Krishna Kumar Yadav
    • Majid Lotfi Ghahroud
    • Ali Akbar Mohammadi
    • Sathiabama T. Thirugnana
    • Shreeshivadasan Chelliapan
    • Marina M.S. Cabral-Pinto
    2021 Environmental Technology & Innovation

    Phosphorus (P) is a vital nutrient for the ecosystems and its excess in wastewater streams leads to some environmental issues such as extensive algae growth (eutrophication). Phytoremediation is a green technology that is based on the combined actions of plants and their associated microbial groups to remove and transfer the toxic compounds in surface water, groundwater and soil. Aquatic plants are widely used for the remediation of contaminated rivers, eutrophic lakes, and other water bodies. In the past three decades, free-floating, submerged, emergent macrophytes and microalgae species have been used for P removal in aquatic plant-based systems such as constructed wetlands (CWs). This paper reviews the recent studies on the potential of aquatic plants such as free-floating, submerged, and emergent plants, and also microalgae for removal of P in different types of wastewaters. Several parameters such as plant species, hydraulic retention time, temperature, type of CWs, effluent concentration, and seasonal changes have effects on P removal. Based on the findings, some of the species such as Azolla and water hyacinth had the highest uptake ability up to 90% while algae species such as Chlorella showed about 70% of P removal. In addition, the mixed culture of aquatic plants can increase P removal if the interaction of the species is considered before cultivation in CWs.

  • Recent Applications of 1D GC-MS and 2D GC-MS in Foodomics Studies
    • Tomasz Majchrzak
    • Kaja Kalinowska
    • Martyna Lubinska-Szczygeł
    • Anna Różańska
    • Tomasz Dymerski
    • Waldemar Wardencki
    • Jacek Namieśnik
    2021

    Gas chromatography coupled with mass spectrometry and food chemistry have been tightly linked since the 1960s. This setup is also an integral part of the omics studies when it comes to low mass metabolites. Therefore, the marriage of GC-MS and foodomics is obvious. Two-dimensional gas chromatography coupled with mass spectrometry fits perfectly within the latest trends in foodomics, since it is tailored for holistic food analysis. In this article, the authors will focus on the current trends in 1D and 2D GC-MS-based foodomics.

  • Recent Developments in Data-Assisted Modeling of Flexible Proteins
    • Cezary Czaplewski
    • Zhou Gong
    • Emilia Lubecka
    • Kai Xue
    • Chun Tang
    • Adam Liwo
    2021 Full text Frontiers in Molecular Biosciences

    Many proteins can fold into well-defined conformations. However, intrinsically-disordered proteins (IDPs) do not possess a defined structure. Moreover, folded multi-domain proteins often digress into alternative conformations. Collectively, the conformational dynamics enables these proteins to fulfill specific functions. Thus, most experimental observables are averaged over the conformations that constitute an ensemble. In this article, we review the recent developments in the concept and methods for the determination of the dynamic structures of flexible peptides and proteins. In particular, we describe ways to extract information from nuclear magnetic resonance small-angle X-ray scattering (SAXS), and chemical cross-linking coupled with mass spectroscopy (XL-MS) measurements. All these techniques can be used to obtain ensemble-averaged restraints or to re-weight the simulated conformational ensembles.

  • Recovering Evaluation of Narrow-Kerf Teeth of Mini Sash Gang Saws
    • Kazimierz Orłowski
    • Daniel Chuchała
    • Tomasz Przybyliński
    • Stanisław Legutko
    2021 Full text Materials

    Sash gang saws with narrow-kerf saw blades are used in the production of glued laminate flooring elements in plants where dry technology is applied. This means that boards or friezes are sawn into top layer lamellae in dry conditions (moisture content of about 10–12%) from expensive wood species, often exotic. The object of this research was stellite-tipped teeth of narrow kerf saw blades sharpened under industrial conditions. A NIKON ECLIPSE Ti-S microscope equipped with a NIKON DS-Fi2 recording camera was used to take pictures of teeth, which were analysed in a graphical software to measure the radii of the main cutting edges. The high-quality images obtained were used to determine the values of the rounding radii of the cutting edges. It was noted that the quality of edges regenerated in industrial conditions, some of which had chipping, was lower than that of brand new saw blades.

  • Recovery of Valuable Materials and Methods for Their Management When Recycling Thin-Film CdTe Photovoltaic Modules
    • Anna Kuczyńska-Łażewska
    • Ewa Klugmann-Radziemska
    • Agnieszka Witkowska
    2021 Full text Materials

    Due to the development of new photovoltaic technologies, there is a need to research new recycling methods for these new materials. The recovery of metals from photovoltaic (PV) modules would reduce the consumption of raw materials. Therefore, the development of recycling technologies for used and damaged modules of newer generations is important for environmental reasons. The aim of the research is to shed light on the nature of the chemical reactions that occur in recycling technology for second-generation photovoltaic modules. This work is focused mainly on cells made of Cadmium Telluride (CdTe). It was proven that prior thermal delamination was necessary. Moreover, an improvement in understanding of the recovery process depending on used leaching solution was achieved.

  • Recycling of Polyurethanes Containing Flame-Retardants and Polymer Waste Transformed into Flame-Retarded Polyurethanes
    • Marcin Włoch
    2021

    The growing number of polyurethanes (PUs) produced every year has developed methods for their mechanical and chemical recycling which yield valuable products like substitutes for commercial polyols or flame-retardants. PUs can be produced in different shapes and forms (i.e., elastomers, flexible or rigid foams, coatings, etc.) using several different components (i.e., di- or polyisocyanates, ester- or ether-based polyols, low-molecular weight chain extenders, fillers, and other modifiers). Therefore, different recycling methods should be considered for a wide range of materials, including postproduction of postconsumer wastes) depending on their chemical structure and properties. This chapter presents a review of selected mechanical (e.g., regrinding and using as a filler, rebonding, and compression molding) and chemical (e.g., glycolysis, glycerolysis, acidolysis and phosphorolysis) recycling methods applicable for PUs. This chapter also presents examples of flame-retardants and flame-retarded PUs obtained by PU recycling, poly(ethylene terephthalate), and melamine formaldehyde foam.

  • Recycling of Waste Rubber by the Manufacturing of Foamed Polyurethane-Based Composites—Current State and Perspectives
    • Aleksander Hejna
    • Krzysztof Formela
    • Łukasz Zedler
    • Paulina Kosmela
    • Adam Olszewski
    2021 Full text Proceedings

    Worn car tires are disruptive waste, and the issue of their management is crucial for the natural environment. In many countries, the primary method of end-of-life tires utilization is energy recovery. However, more effective and beneficial for the environment is material recycling. Using them for the production of polymer-rubber composites seems to be an auspicious direction of research. Incorporation of ground tire rubber into polyurethane matrix should be considered as a method of waste rubber utilization. Moreover, it could significantly reduce the use of petroleum-based polyols and isocyanates, which are commonly considered as toxic chemicals. Therefore, the total impact on the environment could be noticeably reduced, which should be considered as very beneficial step towards more “green” polymer composites. This work aims to summarize the literature reports related to the foamed polyurethane/ground tire rubber composites. It particularly emphasizes the need for compatibilization of these materials by the enhancement of interfacial interactions between the polyurethane matrix and rubber filler phase, which significantly affect the performance properties of prepared materials. As an example, we presented our research results. Besides, future trends and limitations related to this type of composite materials are underlined.

  • Recycling of Waste Rubber by Thermo-Mechanical Treatment in a Twin-Screw Extruder
    • Łukasz Zedler
    • Paulina Kosmela
    • Adam Olszewski
    • Paulina Burger
    • Krzysztof Formela
    • Aleksander Hejna
    2021 Full text Proceedings

    Recycling of waste tires is a significant issue considering both environmental and economic aspects. One of the leading recycling routes is the shredding of tires resulting in the generation of ground tire rubber. This material can be easily introduced into various polymer matrices as a filler, reducing the use of conventionally applied petroleum-based materials. In such cases, it is essential to ensure sufficient interfacial compatibility, which could be achieved by the proper modification of the rubber surface. Different methods of treatment of ground tire rubber aim to activate its surface and introduce functional groups, which could provide the possibility for interfacial interactions and incorporation of the significant amounts of recycled material. Therefore, in the presented paper, we examined the impact of thermo-mechanical treatment in twin-screw extruder on the appearance and chemical structure of ground tire rubber. Moreover, for each set of process parameters, the specific mechanical energy required for the processing was calculated, which could provide essential insights for the potential industrial application of the analyzed process. The energy demand should be considered as a very important issue during development of “greener” processes and materials.

  • Redox property switching in MOFs with open metal sites for improved catalytic hydrogenation performance
    • Longlong Geng
    • Wenfeng Zhou
    • Xiaoli Wang
    • Tingting Li
    • Andrzej Nowak
    • Zhongmin Liu
    • Yong-Zheng Zhang
    • Da-Shuai Zhang
    • Xiuling Zhang
    • Haixiang Han
    2021 JOURNAL OF ALLOYS AND COMPOUNDS

    In this study, a decompression-thermalization strategy was utilized for a Cu-containing metal-organic framework (MOF) to tune its redox and catalytic hydrogenation properties. Remarkably, at just 120 °C, open metal sites (OMSs) were successfully constructed by removing coordinated solvent molecules to generate the daughter MOF-120. The tailored redox property of MOF-120 is correlated with the presence of OMSs. Compared with the pristine MOF where copper cations were capped by DMF, MOF-120 exhibited improved kinetics, showed a reduction of activation energy and outstanding recyclability in the hydrogenation of 4-nitrophenol under mild conditions (25 °C, 1 atm). Both experimental studies and theoretical calculation results reveal that the generation of OMSs endows the Cu species with unique electronic properties, which assist the adsorption and electron transfer between substrate molecules and is responsible for the enhanced performance in the hydrogenation process.

  • Reduced-Cost Microwave Design Closure by Multi-Resolution EM Simulations and Knowledge-Based Model Management
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    • Piotr Płotka
    2021 Full text IEEE Access

    Parameter adjustment through numerical optimization has become a commonplace of contemporary microwave engineering. Although circuit theory methods are ubiquitous in the development of microwave components, the initial designs obtained with such tools have to be further tuned to improve the system performance. This is particularly pertinent to miniaturized structures, where the cross-coupling effects cannot be adequately accounted for using equivalent networks. For the sake of reliability, design closure is normally performed using full-wave electromagnetic (EM) simulation models, which entails considerable computational expenses, often impractically excessive. Available mitigation techniques include acceleration of the conventional (e.g., gradient-based) routines using adjoint sensitivities or sparse sensitivity updates, surrogate-assisted and machine learning algorithms, the latter often combined with nature-inspired procedures. Another alternative is the employment of variable-fidelity simulations (e.g., space mapping, co-kriging), which is most often limited to two levels of accuracy (coarse/fine). This work discusses an EM model management approach coupled with trust-region gradient-based routine, which exploits problem-specific knowledge for continuous (multi-level) modification of the discretization density of the microwave structure at hand in the course of the optimization run. The optimization process is launched at the lowest discretization level, thereby allowing for low-cost exploitation of the knowledge about the device under study. Subsequently, based on the convergence indicators, the model fidelity is gradually increased to ensure reliability. The simulation fidelity selection is governed by the algorithm convergence indicators. Computational speedup is achieved by maintaining low resolution in the initial stages of the optimization run, whereas design quality is secured by eventually switching to the high-fidelity model when close to concluding the process. Numerical verification is carried out using two microstrip circuits, a dual-band power divider and a dual-band branch-line coupler, with the average savings of almost sixty percent when compared to single-fidelity optimization.

  • Regularized identification of fast time-varying systems - comparison of two regularization strategies
    • Artur Gańcza
    • Maciej Niedźwiecki
    2021 Full text

    The problem of identification of a time-varying FIR system is considered and solved using the local basis function approach. It is shown that the estimation (tracking) results can be improved by means of regularization. Two variants of regularization are proposed and compared: the classical L2 (ridge) regularization and a new, reweighted L2 one. It is shown that the new approach can outperform the classical one and is computationally attractive.

  • Regularized Identification of Time-Varying FIR Systems Based on Generalized Cross-Validation
    • Artur Gańcza
    • Maciej Niedźwiecki
    2021 Full text

    A new regularization method is proposed and applied to identification of time-varying finite impulse response systems. We show, that by a careful design of the regularization constraint, one can improve estimation results, especially in the presence of strong measurement noise. We also show that the the most appropriate regularization gain can be found by direct optimization of the generalized cross-validation criterion.

  • Regularized Local Basis Function Approach to Identification of Nonstationary Processes
    • Artur Gańcza
    • Maciej Niedźwiecki
    • Marcin Ciołek
    2021 Full text IEEE TRANSACTIONS ON SIGNAL PROCESSING

    The problem of identification of nonstationary stochastic processes (systems or signals) is considered and a new class of identification algorithms, combining the basis functions approach with local estimation technique, is described. Unlike the classical basis function estimation schemes, the proposed regularized local basis function estimators are not used to obtain interval approximations of the parameter trajectory, but provide a sequence of point estimates corresponding to consecutive instants of time. Based on the results of theoretical analysis, the paper addresses and solves all major problems associated with implementation of the new class of estimators, such as optimization of the regularization matrix, adaptive selection of the number of basis functions and the width of the local analysis interval, and reduction of complexity of the computational algorithms.

  • Reinforcement Learning Algorithm and FDTD-based Simulation Applied to Schroeder Diffuser Design Optimization
    • Adam Kurowski
    • Bożena Kostek
    2021 Full text IEEE Access

    The aim of this paper is to propose a novel approach to the algorithmic design of Schroeder acoustic diffusers employing a deep learning optimization algorithm and a fitness function based on a computer simulation of the propagation of acoustic waves. The deep learning method employed for the research is a deep policy gradient algorithm. It is used as a tool for carrying out a sequential optimization process the goal of which is to maximize the fitness function based on parameters characterizing the autocorrelation diffusion coefficient of the designed acoustic diffuser. As the autocorrelation acoustic diffusion coefficients are calculated from the polar response of a diffuser, the FDTD (finite-difference time-domain) simulation method is used to obtain a set of impulse responses necessary to calculate the polar responses of the optimized Schroeder diffusers. The results obtained from optimization based on the deep learning algorithm were compared with the outcomes of an analogous algorithm employing a genetic algorithm, and based on random selection of the Schroeder diffuser well depth pattern. We found that the best result was achieved by the deep policy gradient, as it produced outcomes, which, in terms of the provided autocorrelation diffusion coefficient, were statistically better than properties of designs provided by two other baseline approaches.

  • Relacja mistrz – uczeń – w jaki sposób kształtować doskonałość akademicką, na przykładzie postaci prof. dr. hab. inż. Romualda Kolmana
    • Piotr Grudowski
    • Małgorzata Wiśniewska
    2021 Problemy Jakości

    W niniejszym artykule skoncentrowano się na zagadnieniu fundamentalnym w kontekście edukacji i rozwoju badań naukowych – relacji mistrz – uczeń. W nawiązaniu do wielowiekowej tradycji instytucji akademickich przedstawiono istotę i znaczenie tych relacji, wskazując pożądane cechy mistrza jako osoby kształtującej oczekiwane ze względów społecznych postawy swoich podopiecznych. Jako przykład postaci mistrza w obszarze nauk o jakości zaprezentowano sylwetkę śp. Profesora Romualda Kolmana oraz wspomnienia niektórych z jego wychowanków. W nawiązaniu do obecnej sytuacji w systemie szkolnictwa wyższego i nauki w Polsce autorzy pragną w ten sposób zwrócić uwagę na – ich zdaniem – zdecydowanie niewystarczające, a wręcz pomijane w różnego rodzaju regulacjach, wsparcie tej sfery aktywności akademickiej