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Gdańsk University of Technology

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  • On thermal stability of piezo-flexomagnetic microbeams considering different temperature distributions
    • Mohammad Malikan
    • Tomasz Wiczenbach
    • Victor Eremeev
    2021 Full text CONTINUUM MECHANICS AND THERMODYNAMICS

    By relying on the Euler–Bernoulli beam model and energy variational formula, we indicate critical temperature causes in the buckling of piezo-flexomagnetic microscale beams. The corresponding size-dependent approach is underlying as a second strain gradient theory. Small deformations of elastic solids are assessed, and the mathematical discussion is linear. Regardless of the pyromagnetic effects, the thermal loading of the thermal environment varies in three states along with the thickness, which is linear, uniform, and parabolic forms. We then establish the results by developing consistent shape functions that independently evaluate boundary conditions. Next, we analytically develop and explore the effective properties of the studied beam concerning vital factors. It was achieved that piezomagnetic-flexomagnetic microbeams are more affected by the thermal environment while the thermal loading is parabolically distributed across the thickness, particularly when the boundaries involve simple supports.

  • On thio‐substituted N‐heterocyclic arsines
    • Johannes Bender
    • Agnieszka Skowrońska
    • Anna Dołęga
    • Martin Nieger
    • Dietrich Gudat
    2021 Full text ZEITSCHRIFT FUR ANORGANISCHE UND ALLGEMEINE CHEMIE

    Metathesis of N-heterocyclic chloroarsines with sulfur-based nucleophiles furnished thio-substituted 1,3,2-diazarsolidines and 1,3,2-diazarsolenes. Crystallographic and NMR spectroscopic studies revealed that a thiocyanato-diazarsolene exhibits a salt-like structure composed of weakly interacting thiocyanate and arsenium ions, while the remaining products formed neutral molecules. The structural data indicate that the heterocyclic framework induces an elongation of exocyclic As−S bonds that is more prominent in diazarsolenes than in diazarsolidines and parallels the bond polarisation effect established for N-heterocyclic phosphines. The NMR data suggest that diazarsolenes undergo facile inversion of the pyramidal configuration at arsenic, which was successfully modelled by DFT studies.

  • On topology optimization of large deformation contact-aided shape morphing compliant mechanisms
    • Prabhat Kumar
    • Roger Sauer
    • Anupam Saxena
    2021 Full text MECHANISM AND MACHINE THEORY

    A topology optimization approach for designing large deformation contact-aided shape morphing compliant mechanisms is presented. Such mechanisms can be used in varying operating conditions. Design domains are described by regular hexagonal elements. Negative circular masks are employed to perform dual task, i.e., to decide material states of each element and also, to generate rigid contact surfaces. Each mask is characterized by five design variables, which are mutated by a zero-order based hill-climbing optimizer. Geometric and material nonlinearities are considered. Continuity in normals to boundaries of the candidate designs is ensured using a boundary resolution and smoothing scheme. Nonlinear mechanical equilibrium equations are solved using the Newton–Raphson method. An updated Lagrange approach in association with segment-to-segment contact method is employed for the contact formulation. Both mutual and self contact modes are permitted. Efficacy of the approach is demonstrated by designing four contact-aided shape morphing compliant mechanisms for different desired curves. Performance of the deformed profiles is verified using a commercial software. The effect of frictional contact surface on the actual profile is also studied.

  • On weak solutions of boundary value problems within the surface elasticity of Nth order
    • Victor Eremeev
    • Leonid Lebedev
    • Michael Cloud
    2021 ZAMM-Zeitschrift fur Angewandte Mathematik und Mechanik

    A study of existence and uniqueness of weak solutions to boundary value problems describing an elastic body with weakly nonlocal surface elasticity is presented. The chosen model incorporates the surface strain energy as a quadratic function of the surface strain tensor and the surface deformation gradients up to Nth order. The virtual work principle, extended for higher‐order strain gradient media, serves as a basis for defining the weak solution. In order to characterize the smoothness of such solutions, certain energy functional spaces of Sobolev type are introduced. Compared with the solutions obtained in classical linear elasticity, weak solutions for solids with surface stresses are smoother on the boundary; more precisely, a weak solution belongs to 1()∩() where ⊂≡ and ⊂ℝ3 .

  • On Wrinkling in Sandwich Panels with an Orthotropic Core
    • Zbigniew Pozorski
    • Jolanta Pozorska
    • Ireneusz Kreja
    • Łukasz Smakosz
    2021 Full text Materials

    This paper deals with the local loss of stability (wrinkling) problem of a thin facing of a sandwich panel. Classical solutions to the problem of facing instability resting on a homogeneous and isotropic substructure (a core) are compared. The relations between strain energy components associated with different forms of core deformations are discussed. Next, a new solution for the orthotropic core is presented in detail, which is consistent with the classic solution for the isotropic core. Selected numerical examples confirm the correctness of the analytical formulas. In the last part, parametric analyses are carried out to illustrate the sensitivity of wrinkling stress to a change in the material parameters of the core. These analyses illustrate the possibility of using the equations derived in the article for the variability of Poisson’s ratio from -1 to 1 and for material parameters strongly deviating from isotropy.

  • Onboard Energy Storage and Power Management Systems forAll-Electric Cargo Vessel Concept
    • Dariusz Karkosiński
    • Wojciech Aleksander Rosiński
    • Piotr Deinrych
    • Szymon Potrykus
    2021 Full text ENERGIES

    This paper presents an innovative approach to the design of a forthcoming, fully electric-powered cargo vessel. This work begins by defining problems that need to be solved when designingvessels of this kind. Using available literature and market research, a solution for the design of apower management system and a battery management system for a cargo vessel of up to 1504 TEUcapacity was developed. The proposed solution contains an innovative approach with three parallelenergy sources. The solution takes into consideration the possible necessity for zero-emission workwith the optional function of operation as an autonomous vessel. Energy storage system based onlithium-ion battery banks with a possibility of expanding the capacity is also described in this work asit is the core part of the proposed solution. It is estimated that the operation range for zero-emissionwork mode of up to 136 nautical miles can be achieved through the application of all fore-mentioned parts.

  • Ongoing progress on novel nanocomposite membranes for the separation of heavy metals from contaminated water
    • Roberto Castro Munoz
    • Luisa Loreti González-Melgoza
    • Octavio García-Depraect
    2021 Full text CHEMOSPHERE

    Membranes, as the primary separation element of membrane-based processes, have greatly attracted the attention of researchers in several water treatment applications, including wastewater treatment, water purification, water disinfection, toxic and non-toxic chemical molecules, heavy metals, among others. Today, the removal of heavy metals from water has become challenging, in which chemical engineers are approaching new materials in membrane technologies. Therefore, the current review elucidates the progress of using different concepts of membranes and potential novel materials for such separations, identifying that polymeric membranes can exhibit a removal efficiency from 77 up to 99%; while novel nanocomposite membranes are able to offer complete removal of heavy metals (up to 100%), together with unprecedented permeation rates (from 80 up to 1, 300 L m−2 h−1). Thereby, the review also addresses the highlighted literature survey of using polymeric and nanocomposite membranes for heavy metal removal, highlighting the relevant insights and denoted metal uptake mechanisms. Moreover, it gives up-to-date information related to those novel nanocomposite materials and their contribution to heavy metals separation. Finally, the concluding remarks, future perspectives, and strategies for new researchers in the field are given according to the recent findings of this comprehensive review.

  • On-line assessment of oil quality during deep frying using an electronic nose and proton transfer reaction mass spectrometry
    • Tomasz Majchrzak
    • Wojciech Wojnowski
    • Agnieszka Głowacz-Różyńska
    • Andrzej Wasik
    2021 FOOD CONTROL

    We describe a novel method for the quality assessment of oil utilized for deep frying. The method is based on the analysis of frying fumes using a custom electronic nose. The quality score could be obtained after less than 3 min of analysis and without interrupting the frying process or sampling the oil directly. The obtained results were correlated with the peroxide value using a multivariate linear regression model. The most relevant variables were selected based on heat maps and on the analysis of variance. The coefficients of determination for palm oil and rapeseed oil were 0.920 and 0.935, respectively. Real-time monitoring of selected VOCs in the frying fumes was performed using proton transfer reaction mass spectrometry. It was shown that 1-heptanol is a possible indicator of rapeseed oil’s quality. The proposed method might be used to supplement the currently available techniques and could find implementation in the non-invasive on-line assessment of frying oils’ quality during deep frying of foodstuffs

  • Ontological Model for Contextual Data Defining Time Series for Emotion Recognition and Analysis
    • Teresa Zawadzka
    • Wojciech Waloszek
    • Aleksandra Karpus
    • Sara Zapalowska
    • Michał Wróbel
    2021 Full text IEEE Access

    One of the major challenges facing the field of Affective Computing is the reusability of datasets. Existing affective-related datasets are not consistent with each other, they store a variety of information in different forms, different formats, and the terms used to describe them are not unified. This paper proposes a new ontology, ROAD, as a solution to this problem, by formally describing the datasets and unifying the terms used. The developed ontology allows information about the origin and meaning of the data to be modeled, i.e., time series, representing both emotional states and features derived from biosignals. Furthermore, the ROAD ontology is extensible and not application-oriented, thus it can be used to store data from a wide range of Affective Computing experiments. The ontology was validated by modeling data obtained from one experiment on the AMIGOS dataset. The approach proposed in the paper can be used both by researchers who create new datasets or want to reuse existing ones, and for those who want to process data from experiments in a more automated way.

  • Open Innovation Competence for a Future-Proof Workforce: A Comparative Study from Four European Universities
    • Marita Mcphillips
    • Magdalena Licznerska
    2021 Full text Journal of Theoretical and Applied Electronic Commerce Research

    Digital transformation is a key driving force of open innovation to capture and transfer knowledge inside and outside of a company’s bounds. New challenges in organizing multiple knowledge flows imply the need for increased competences related to this paradigm of future employees. In this article, we organize and aggregate the competencies required for open innovation collaboration and develop a competence profile that organizes individual competencies in an open innovation context. Based on elements of the European Entrepreneurship Competence Framework, we delineate an OI Competence Profile and list the core competencies to manage and accelerate the inflow and outflow of knowledge. We explore this profile by comparing data from 2332 students from four European universities to find differences in the distribution of OI competencies between countries. The study contributes to understanding the individual competencies that target the future OI needs of companies necessary in the context of digital transformation. It also introduces an interdisciplinary approach to integrate the research streams of management practice, open innovation, and entrepreneurial education.

  • Opinia na temat celowości oraz zakresu rzeczowego remontu tokarki karuzelowej FKD-60/80. Ekspertyza techniczna opracowana na zlecenie ENEROMONTAŻ-PÓŁNOC GDYNIA S.A.
    • Wojciech Blacharski
    2021

    Opracowana Opinia Jednostki Naukowej dotyczyła ciężkiej tokarki karuzelowej typu FKD-60/80 ze sterowaniem CNC. Na podstawie przeprowadzonego w miejscu użytkowania tej obrabiarki audytu, dokonano oceny obecnego stanu maszyny oraz przeanalizowano przyczyny awarii, które zdarzały się w okresie jej eksploatacji. Zakres analizy przyczyn stanów awaryjnych obejmował: - awarie zespołu elektrowrzeciona oraz układów hydraulicznych zawartych w tym zespole; - obserwowane ugięcia i błędy geometryczne stołu obrotowego (oś C) ulokowanego na prowadnicy hydrostatycznej oraz ocenę dopuszczalnej obciążalności tego stołu; - problemy z napędem ruchu belki w kierunku pionowym (oś W); - usterki w układach smarowania i układach hydraulicznych; - problemy z układem sterowania. W opracowaniu określono zakres koniecznych prac remontowych oraz zaproponowano wprowadzenie działań zapobiegawczych w ramach utrzymania ruchu. Przeanalizowano również ograniczenia możliwości obróbkowych tokarki FKD-60/80 w kontekście potrzeb produkcyjnych firmy użytkującej tą maszynę. Opracowanie zawiera 28 stron, 7 rysunków i 7 fotografii.

  • Opinia na temat celowości oraz zakresu rzeczowego remontu wytaczarko-frezarki płytowej typu FLF16/CNC. Ekspertyza techniczna opracowana na zlecenie ENEROMONTAŻ-PÓŁNOC GDYNIA S.A.
    • Wojciech Blacharski
    2021

    Opracowana Opinia Jednostki Naukowej dotyczyła ciężkiej wytaczarko-frezarki płytowej typu FLF16/CNC ze sterowaniem CNC. Na podstawie przeprowadzonego w miejscu użytkowania tej obrabiarki audytu, dokonano oceny obecnego stanu maszyny oraz przeanalizowano przyczyny awarii, które zdarzały się w okresie jej eksploatacji. Zakres analizy przyczyn problemów eksploatacyjnych i stanów awaryjnych obejmował: - awarie zespołu elektrowrzeciona oraz układów hydraulicznych zawartych w tym zespole; - usterki głowicy przechylnej do elektrowrzeciona; - usterki w układach napędowych osi liniowych, w tym osi X (ruch liniowy stojaka w kierunku poziomym, osi Y (ruch liniowy suwaka w kierunku pionowym), osi Z (ruch liniowy belki wrzeciennika); - problemy ze zbyt dużymi błędami geometrycznymi ustawienia głównych zespołów obrabiarki i niedotrzymywaniem wymagań WOT; - usterki układów smarowania i hydrauliki; - problemy z układem sterowania. W opracowaniu określono zakres prac remontowych, które byłyby konieczne dla przywrócenia maszyny do jej stanu początkowego. Wskazano również na istotne ograniczenia możliwości obróbkowych wytaczarko frezarki FLF16/CNC w kontekście aktualnych potrzeb produkcyjnych firmy użytkującej tą maszynę. Opracowanie zawiera 25 stron, 1 rysunek i 10 fotografii.

  • Opioid Growth Factor and its Derivatives as Potential Non-toxic Multifunctional Anticancer and Analgesic Compounds
    • Justyna Budka
    • Szymon Kowalski
    • Monika Chylińska
    • Krystyna Dzierzbicka
    • Iwona Inkielewicz-Stępniak
    2021 Full text CURRENT MEDICINAL CHEMISTRY

    In this paper, we review the structure-activity relationship of OGF and its analogues. We highlight also OGF derivatives with analgesic, immunomodulatory activity and the ability to penetrate the blood-brain barrier and may be used as safe agents enhancing chemotherapy efficacy and improving quality of life in cancer patients. The reviewed papers indicate that Met-enkephalin and its analogues are interesting candidates for the development of novel, non-toxic, and endowed with an analgesic activity anticancer drugs. More preclinical and clinical studies are needed to explore these opportunities.

  • Opłacalność zastosowania pompy ciepła w układach centralnego ogrzewania i ciepłej wody użytkowej
    • Karol Olszewski
    • Blanka Jakubowska
    2021 Ciepłownictwo, Ogrzewnictwo, Wentylacja

    W artykule przedstawiono problem opłacalności ekonomicznej stosowania pompy ciepła, w układach ciepłej wody użytkowej oraz centralnego ogrzewania. Zasadność zastosowania takich źródeł ciepła w tych instalacjach spowodowana jest ogólnoświatowymi kierunkami i stopniowym odchodzeniem od konwencjonalnych źródeł energii takich jak kotły olejowe lub gazowe. Przedmiotem artykułu był budynek jednorodzinny o powierzchni użytkowej ok. 145 m2, w którym instalacja c.o. oraz c.w.u. byłaby zasilana gruntową pompą ciepła. Do analizy przyjęto dwa warianty instalacji c.o., tj. dwururową grzejnikową z rozdziałem dolnym oraz ogrzewanie podłogowe. W przypadku instalacji ciepłej wody użytkowej przyjęto jeden wariant układu centralnego przygotowaniu c.w.u. i magazynowanej w zbiorniku znajdującym się wewnątrz obudowy pompy ciepła. Do analizy opłacalności użyto metodę prostego czasu zwrotu nakładów inwestycyjnych, w której pompa ciepła została porównana z konwencjonalnym źródłem ciepła.

  • Optical fiber aptasensor for label-free bacteria detection in small volumes
    • Monika Janik
    • Ewa Brzozowska
    • Paula Czyszczoń
    • Anna Celebańska
    • Marcin Koba
    • Andrzej Gamian
    • Wojtek J. Bock
    • Mateusz Śmietana
    2021 SENSORS AND ACTUATORS B-CHEMICAL

    Highly sensitive devices for fast bacteria detection are sought to be developed with the task of quantifying the worldwide problem of pathogenic bacteria and thus helping to take control over spreading bacterial infections. This work concerns a sensing solution based on microcavity in-line Mach-Zehnder interferometer (μIMZI) induced in an optical fiber. Such a device exhibits ultrahigh sensitivity to refractive index changes in the microcavity. We show that for well-adjusted chemical surface functionalization combined with highly specific low-molecular-weight bioreceptor the μIMZI can also be used for efficient label-free bacteria detection. The detection capability has been shown for peptide aptamers and pathogenic E. coli O157:H7 bacteria used as a bioreceptor and a target, respectively. We have found that the sensor is capable of detecting bacteria concen-trations as low as 10 colony-forming units per mL in a sample which volume may be as small as hundreds of picoliters. The selectivity of the synthesized peptides is additionally confirmed by Enzyme-Linked Immunosor-bent Assay (ELISA). Based on the presented performance, the μIMZI sensor is one of the most sensitive and lowest-analyte-volume label-free biosensors among fiber optical platforms to date

  • Optical flow method for measuring deformation of soil specimen subjected to torsional shearing
    • Piotr Srokosz
    • Marcin Bujko
    • Marta Bocheńska
    • Rafał Ossowski
    2021 Full text MEASUREMENT

    In this study optical flow method was used for soil small deformation measurement in laboratory tests. The main objective was to observe how the deformation distributes along the whole height of cylindrical soil specimen subjected to torsional shearing (TS test). The experiments were conducted on dry non-cohesive soil specimens under two values of isotropic pressure. Specimens were loaded with low-amplitude cyclic torque to analyze the deformation within the small strain range (0.001–0.01%). Optical flow method variant by Ce Liu (2009) was used for motion estimation from series of images. This algorithm uses scale-invariant feature transform (SIFT) for image feature extraction and coarse-to-fine matching scheme for faster calculations. The results were validated with the Particle Image Velocimetry (PIV). The results show that the displacement distribution deviates from commonly assumed linearity. Moreover, the observed deformation mechanisms analysis suggest that the shear modulus G commonly determined through TS tests can be considerably overestimated.

  • Optical Spectroscopic Studies of Tetrahydrofuran Fragmentation Induced by Collisions with Dihydrogen Cations
    • Tomasz Wąsowicz
    • Bogusław Pranszke
    2021 Full text ACTA PHYSICA POLONICA A

    Collisions of dihydrogen cations with tetrahydrofuran molecules have been studied. Luminescence spectra and the emission functions of the excited products at projectile energies ranging from 8 to 1000 eV have been measured using collision-induced emission spectroscopy. The recorded spectra are dominated by the atomic lines of the hydrogen Balmer series, whose intensities decrease more quickly than derived by the quantum-theoretical principle. The spectra also exhibit weak molecular bands of vibrationally and rotationally excited diatomic CH fragments created in the A2D and B2S ectronic states. The collisional processes are identified and compared with the latest results on cation-induced fragmentation of tetrahydrofuran.

  • Optical-Fiber Microsphere-Based Temperature Sensors with ZnO ALD Coating—Comparative Study
    • Paulina Listewnik
    • Mikhael Bechelany
    • Paweł Wierzba
    • Małgorzata Szczerska
    2021 Full text SENSORS

    This study presents the microsphere-based fiber-optic sensor with the ZnO Atomic Layer Deposition coating thickness of 100 nm and 200 nm for temperature measurements. Metrological properties of the sensor were investigated over the temperature range from 100 °C to 300 °C, with a 10 °C step. The interferometric signal was used to monitor the integrity of the microsphere and its attachment to the connecting fiber. For the sensor with a 100 nm coating, a spectrum shift of the reflected signal and the optical power of the reflected signal were used to measure temperature, while only the optical power of the reflected signal was used in the sensor with a 200 nm coating. The R2 coefficient of the discussed sensors indicates a linear fit of over 0.99 to the obtained data. The sensitivity of the sensors, investigated in this study, equals 103.5 nW/°C and 19 pm/°C or 11.4 nW/°C for ZnO thickness of 200 nm and 100 nm, respectively.

  • OPTIMAL FARM SIZE AND EFFECTIVENESS OF AGRICULTURE IN THE EU: THE CASE OF WHEAT YIELDS
    • Roman Skalicky
    • Elżbieta Rogalska
    • Michał Pietrzak
    • Marek Zinecker
    • Jana Meluzinova
    2021 Full text Transformations in Business & Economics

    The article concentrates on the relationship between the size of a farm and its efficiency in relation to wheat production in the European Union (EU). The issue is not new, however fundamental from the point of view of the agricultural policy, as the appropriate shape of the agrarian structure affects the economic rationality in agriculture and significantly improves the productivity. We analysed data for the period between 2004 to 2016 while using the Farm Accountancy Data Network. The fixed effects model was used to identify the explanatory variables for farm size and wheat yields. We calculate the yields per hectare as the ratio of the sum of input costs per hectare to the cost of producing a unit of yield per hectare. Using the 1st derivative, we then estimate the marginal cost of the inputs for each of the farm size categories. Our main conclusion is that with the growing size of a farm, there is a continuous increase in yields of wheat per hectare. This result is achieved by increasing the specific crop costs, a significant part of which are fertilizers and crop protection products, both with respect to the cultivated area and the production achieved. When evaluating the efficiency of production, the optimal size of the economic unit (according to the FADN categorization) is 5. Up to the size category 5, there is an increase in production with respect to the monetary value of production inputs. In the case of larger farms, the ratio is declining.

  • Optimal Rotating Receiver Angles Estimation for Multicoil Dynamic Wireless Power Transfer
    • Bohdan Pakhaliuk
    • Viktor Shevchenko
    • Jan Mućko
    • Oleksandr Husev
    • Mykola Lukianov
    • Piotr Kołodziejek
    • Natalia Strzelecka
    • Ryszard Strzelecki
    2021 Full text ENERGIES

    This study proposed an approach to dynamic wireless charging that uses a rotating receiver coil. Our simulation study focused on the verification of a novel way of increasing the coupling coefficient and power transfer stability by following the flux of the transmitting coils. To obtain the highest possible coupling by means of the FEM analysis, we studied the optimization of the trajectory of the angular velocity of the rotating receiver. The coupling coefficient trajectories that were obtained were simulated by means of the state space model with three transmitters. Our comprehensive analysis showed that the proposed approach of wireless power transmission enabled a 40% increase in the usage of track space

  • Optimisation and field assessment of poroelastic wearing course bond quality
    • Piotr Jaskuła
    • Dawid Ryś
    • Cezary Szydłowski
    • Marcin Stienss
    • Łukasz Mejłun
    • Mariusz Jaczewski
    • Grzegorz Ronowski
    2021 Full text Road Materials and Pavement Design

    Compared to typical asphalt mixtures, poroelastic mixtures are characterised by high porosity and high flexibility, which are desirable for traffic noise reduction. However, the same properties increase the risk of debonding from the lower layer, which is a significant source of premature damage. The study investigates which of the factors – tack coat agent, type and texture of the lower layer – have the greatest impact on interlayer bonding quality. From 27 variants of interface bond techniques investigated in laboratory, 8 were selected and constructed on two full-scale test sections. Monotonic direct shear loading and cyclic direct shear loading tests with normal force were used for this purpose. The tests indicated that softer bitumen used for the tack coat and the milled texture of the lower layer improves bond quality. However the appropriate laying compaction has the major influence. Poroelastic mixtures are much more sensitive to technological imperfections than standard asphalt mixtures.

  • Optimization of carbamazepine photodegradation on defective TiO2-based magnetic photocatalyst
    • Szymon Dudziak
    • Zuzanna Bielan
    • Paweł Kubica
    • Anna Zielińska-Jurek
    2021 Full text Journal of Environmental Chemical Engineering

    In this work, carbamazepine (CBZ) degradation over defective Fe3O4@SiO2/d-TiO2/Pt photocatalyst was studied. Within the titania structure, Ti vacancies and Pt nanoparticles were introduced to enhance the photocatalyst’s light absorption and influence charge carriers’ mobility. For the carbamazepine degradation, process parameters, e.g., temperature, flux intensity, photocatalyst loading, aeration, pH, and addition of H2O2, were optimized for 4 or 5 different levels, with the quadratic model including 2-factor interactions determined to analyze the effect of these parameters. Carbamazepine presence and by-product formation were monitored using the HPLC-DAD system together with additional HPLC-TOFMS analysis for further identification of created compounds. Acridine was selected as an additional factor, indicating differences in the performed process of photolysis and photocatalytic CBZ degradation. Pure TiO2 exhibited the highest efficiency of CBZ degradation under alkaline conditions, while the performed optimization shows that a combination of H+ and H2O2 addition is crucial to achieve high CBZ removal and its mineralization in the presence of Fe3O4@SiO2/d-TiO2/Pt photocatalyst. The obtained results were discussed concerning photocatalyst structure, generation of reactive oxygen species inside H+/H2O2/photocatalyst system, and the possible effect of introduced Ti vacancies. In terms of reusability, the performance of Fe3O4@SiO2/d-TiO2/Pt photocatalyst was stable after 8 subsequent cycles of carbamazepine degradation.

  • Optimization of Data Assignment for Parallel Processing in a Hybrid Heterogeneous Environment Using Integer Linear Programming
    • Tomasz Boiński
    • Paweł Czarnul
    2021 Full text COMPUTER JOURNAL

    In the paper we investigate a practical approach to application of integer linear programming for optimization of data assignment to compute units in a multi-level heterogeneous environment with various compute devices, including CPUs, GPUs and Intel Xeon Phis. The model considers an application that processes a large number of data chunks in parallel on various compute units and takes into account computations, communication including bandwidths and latencies, partitioning, merging, initialization, overhead for computational kernel launch and cleanup. We show that theoretical results from our model are close to real results as differences do not exceed 5% for larger data sizes, with up to 16.7% for smaller data sizes. For an exemplary workload based on solving systems of equations of various sizes with various compute-to-communication ratios we demonstrate that using an integer linear programming solver (lp_solve) with timeouts allows to obtain significantly better total (solver+application) run times than runs without timeouts, also significantly better than arbitrary chosen ones. We show that OpenCL 1.2’s device fission allows to obtain better performance in heterogeneous CPU+GPU environments compared to the GPU-only and the default CPU+GPU configuration, where a whole device is assigned for computations leaving no resources for GPU management.

  • Optimization of the Aeration Strategies in a Deammonification Sequencing Batch Reactor for Efficient Nitrogen Removal and Mitigation of N2O Production
    • Hussein Al-Hazmi
    • Lu Xi
    • Joanna Majtacz
    • Przemysław Kowal
    • Li Xie
    • Jacek Mąkinia
    2021 Full text ENVIRONMENTAL SCIENCE & TECHNOLOGY

    In deammonification systems, nitrite-oxidizing bacteria (NOB) suppression and nitrous oxide (N2O) mitigation are two important operational objectives. To carry out this multivariable analysis of response, a comprehensive model for the N cycle was developed and evaluated against experimental data from a laboratory-scale deammonification granular sludge sequencing batch reactor. Different aeration strategies were tested, and the manipulated variables comprised the dissolved oxygen (DO) set point in the aerated phase, aeration on/off frequency (F), and the ratio (R) between the non-aerated and aerated phase durations. Experimental results showed that a high ammonium utilization rate (AUR) in relation to the low nitrate production rate (NPR) (NPR/AUR = 0.07−0.08) and limited N2O emissions (EN2O < 2%) could be achieved at the DO set point = 0.7 mg O2/L, R ratio = 2, and F frequency = 6−7 h−1 . Under specific operational conditions (biomass concentration, NH4 + -N loading rate, and temperature), simulation results confirmed the feasible aeration strategies for the trade-offs between the NOB suppression and N2O emission. The intermittent aeration regimes led to frequent shifts in the predominating N2O production pathways, that is, hydroxylamine (NH2OH) oxidation (aerated phase) versus autotrophic denitrification (non-aerated phase). The inclusion of the extracellular polymeric substance mechanism in the model explained the observed activity of heterotrophs, especially Anaerolineae, and granule formation.

  • OPTIMIZATION OF THE LAST STAGE OF GAS-STEAM TURBINE USING A HYBRID METHOD
    • Paweł Ziółkowski
    • Łukasz Witanowski
    • Piotr Klonowicz
    • Stanisław Głuch
    2021

    This paper relates to the CFD calculation of a new turbine type which is in the phase of theoretical analysis, because the working fluid is a mixture of steam and gas generated in wet combustion chamber. At first, this article concentrates on a possibility of streamlining the flow efficiency of a last stage of axial turbine working on gas-steam mixture using a hybrid of the particle swarm optimization algorithm with the Nelder-Mead method called HNMPSO. Subsequently, this article aim is to redesign and analyze the flow characteristics of the last stage of the gas-steam turbine. Values of the maximized objective function, which is the isentropic efficiency of the turbine stage, are found from 3D RANS computation of the flowpath geometry changing during the improving scheme. Among the optimized variables are parameters characterising the shape of the endwall contours within the rotor domain.

  • Optimization of the Relative Humidity of Reactant Gases in Hydrogen Fuel Cells Using Dynamic Impedance Measurements
    • Ewa Janicka
    • Michał Mielniczek
    • Łukasz Gaweł
    • Kazimierz Darowicki
    2021 Full text ENERGIES

    Water management is a key factor affecting the efficiency of proton exchange membrane fuel cells (PEMFCs). The currently used monitoring methods of PEMFCs provide limited information about which processes or components that humidity has a significant impact upon. Herein, we propose the use of a novel approach of impedance measurements using a multi-sinusoidal perturbation signal, which enables impedance measurements under dynamic operating conditions. The manuscript presents the effect of the relative humidity (RH) of the reactants on the instantaneous impedance of the middle cell in the PEMFC stack as a function of the current load. Analysis of changes in the values of equivalent circuit elements was carried out to determine which process determines the stack’s performance depending on the load range of the fuel cell during operation. Comprehensive impedance analysis showed that to ensure optimal cell operation, the humidity of the reactants should be adjusted depending on the load level. The results showed that at low-current loads, the humidity of gases should be at least 50%, while at high-current loads, the cell should operate optimally at a gas humidity of 30% or lower. The presented methodology provides an important tool for optimizing and monitoring the operation of fuel cells.

  • Optimization of thermal backfill configurations for desired high-voltage power cables ampacity
    • Stanisław Czapp
    • Filip Ratkowski
    2021 Full text ENERGIES

    The ampacity of high-voltage power cables depends, among others, on their core cross-sectional area as well as thermal resistivity of the thermal backfill surrounding the cables. The cross-sectional area of the power cables’ core is selected according to the expected power to be transferred via the cable system. Usually, the higher the power transfer required, the higher the cross-sectional area of the core. However, the cost of high-voltage power cables is relatively high and strictly depends on the dimensions of the core. Therefore, from the economic point of view, it is interesting to focus on the improvement of the thermal condition around the cables, by changing the dimension of the thermal backfill, instead of increasing the power cables’ core cross-sectional area. In practice, it is important to find the optimal dimensions of both cable core and thermal backfill to achieve the economically attractive solution of the power cable transfer system. This paper presents a mathematical approach to the power-cable system design, which enables selecting the cost-optimal cross-section of a power cable core depending on the dimensions of the thermal backfill. The proposal herein allows us to indicate the condition in which it is advantageous to increase the core cross-sectional area or to expand the dimension of the backfill. In this approach, the optimal backfill geometry can also be evaluated. The investment costs of the 110 kV power cable system with the core cross-sectional areas consecutively equal to 630, 800 and 1000 mm2 have been compared.

  • Optimization of Train Energy Cooperation Using Scheduled Service Time Reserve
    • Michał Urbaniak
    • Ewa Kardas-Cinal
    2021 Full text ENERGIES

    The main aim of the paper was to develop an innovative approach to the preliminary estimation possibility of train energy cooperation based on data from timetables, without traction calculations. The article points out the need to strive for sustainable and environmentally friendly transport. It was pointed out that rail transport using electric traction is one of the more ecological branches of transport. It also offers a number of possibilities for improving energy efficiency and reducing energy consumption, one of which is the recovery and reuse of energy lost in the electrodynamic braking process. The main ways in which such energy can be used are listed, but the focus is mainly on the aspect of the so-called “energy cooperation” of trains. Then, the current state of the research and knowledge on the narrowed scope of rail traffic management and recuperative braking in rail transportation is presented; an innovative approach to the indirect optimization of the amount of recuperated electrical energy immediately usable by another vehicle by maximizing the duration of energy co-optimization is proposed; and the authors’ function is proposed to enable optimization, taking into account various parameters. The optimization was performed with the use of a proprietary, multi-criteria objective function and the Solver optimization module. Finally, the results obtained using the proposed approach are presented and illustrated with the example of train timetables used by some of the largest railway stations in Poland.

  • Optimization-based antenna miniaturization using adaptively-adjusted penalty factors
    • Marzieh Mahrokh
    • Sławomir Kozieł
    2021 Full text Electronics

    The continuing trend for miniaturization of electronic devices necessitates size reduction of the comprising components and circuitry. Specifically, integrated circuit-antenna modules therein require compact radiators in applications such as 5G communications, implantable and on-body devices, or internet of things (IoT). The conflict between the demands for compact size and elec-trical and field performance can be mitigated by means of constrained numerical optimization. Evaluation of performance-related constraints requires expensive electromagnetic (EM) analysis of the system at hand, therefore their explicit handling is inconvenient. A workaround is the penalty function approach where the primary objective (typically, antenna size) is complement-ed by additional terms quantifying possible constraint violations. The penalty coefficients that determine contributions of these terms, are normally adjusted manually, which hinders precise control over antenna performance figures and often leads to inferior results in terms of achieved miniaturization rates. This paper proposes a novel algorithm featuring an automated adjust-ment of the penalty factors throughout the optimization process. Our methodology is validated using three broadband antenna structures. The obtained results demonstrate that the presented adaptive adjustment permits a precise control over the constraint violations while leading to better miniaturization rates as compared to manual penalty term setup.

  • Optimizing FSO networks resilient to adverse weather conditions by means of enhanced uncertainty sets
    • Ilya Kalesnikau
    • Marinela Shehaj
    • Dritan Nace
    • Michał Pióro
    2021 Optical Switching and Networking

    This work deals with dimensioning of wireless mesh networks (WMN) composed of FSO (free space optics) links. Although FSO links realize broadband transmission at low cost, their drawback is sensitivity to adverse weather conditions causing transmission degradation on multiple links. Hence, designing such FSO networks requires an optimization model to find the cheapest configuration of link capacities that will be able to carry an acceptable level of the demanded traffic in all weather states that can be foreseen in network operation. Such a model can be achieved using robust optimization techniques, and for that it is important to find a tractable way of characterizing possible link (capacity) degradation states corresponding to weather conditions not known in advance. In the paper we show how the set of link degradation states may be represented mathematically in a compact and tractable way to be exploited in optimization. To solve this task we will make use of a generalization of a combinatorial problem of finding a minimum hitting set to deduce a compact set approximating a given set of link degradation states, (called uncertainty set). Finally, we provide a mathematical model with respect to a general form of uncertainty sets and illustrate the effectiveness of our model by means of a numerical study.

  • Organic syntheses greenness assessment with multicriteria decision analysis
    • Marek Tobiszewski
    • Witold Przychodzeń
    • Marta Bystrzanowska
    • Maria Milewska
    2021 Full text GREEN CHEMISTRY

    Green chemistry requires a metrics system that is comprehensive by the criteria included and simple in the application at the same time. We propose the application of multicriteria decision analysis for com- parative greenness assessment of organic synthesis procedures. The assessment is based on 9 criteria (the reagent, reaction efficiency, atom economy, temperature, pressure, synthesis time, solvent, catalyst and reactant) for which data points are easily extractable from synthesis protocols. The criteria are given weights by two experts to differentiate their relative importance. Two datasets are created, one of the pro- cedures for benzoic acid synthesis, the second one of procedures for γ-valerolactone synthesis. In both cases, the greenest procedure is identified and the remaining ones are ranked according to their green- ness. The proposed assessment procedure incorporates more assessment criteria than product/waster ratio mass-based metric and is much less tedious than the application of life-cycle assessment.

  • Otwarte innowacje w polskich małych i średnich przedsiębiorstwach
    • Natalia Przybylska
    2021

    Niniejsza monografia poświęcona jest analizie związku między działalnością in­nowacyjną małych i średnich przedsiębiorstw a otwartymi innowacjami. Publikacja wpisuje się w szeroki nurt badań empirycznych nad otwar­tymi innowacjami oraz stanowi uzupełnienie luki poznawczej dotyczącej badania zależności między wykorzystaniem OI a aktywnością innowacyjną polskich małych i średnich przedsiębiorstw. Badania empiryczne, których fragment zaprezentowano w monografii, zostały przeprowadzone w 2015 roku na reprezenta­tywnej próbie małych i średnich przedsiębiorstw w Polsce.

  • Otwarte zasoby edukacyjne - przegląd inicjatyw w Polsce i na świecie
    • Kamila Kokot-Kanikuła
    • Anna Wałek
    2021 Full text e-mentor

    Otwarte zasoby edukacyjne (OZE) to materiały szkoleniowe oraz narzędzia wspierające zarówno uczenie, jak i nauczanie. Zjawisko to nierozerwalnie łączy się z szerszym pojęciem otwartej edukacji (OE), które postuluje zniesienie barier w nauczaniu tak, aby uczący się mogli zdobywać wiedzę zgodnie ze swoimi potrzebami edukacyjno-szkoleniowymi. Celem artykułu jest zapoznanie czytelników z zagadnieniem otwartych zasobów edukacyjnych, prezentacja kluczowych dla ich powstania i rozwoju podstaw prawnych i organizacyjnych oraz przedstawienie najnowszych inicjatyw podejmowanych w zakresie upowszechniania OZE. W pierwszej części artykułu wyjaśnione zostały pojęcia oraz rola otwartych zasobów edukacyjnych w procesie nauczania, a następnie zaprezentowane wybrane inicjatywy realizowane przez członków European Network of Open Education Librarians (ENOEL), a także wyniki ankiety przeprowadzonej wśród pracowników europejskich bibliotek akademickich przez organizację SPARC Europe. Analiza piśmiennictwa, treści dokumentów prawnych, raportów i rekomendacji pozwoliła na precyzyjne określenie znaczenia otwartych zasobów edukacyjnych dla ich użytkowników. Wieloaspektowość działań oraz ich skala potwierdzają, że nowoczesne nauczanie może rozwijać się szybciej w oparciu o otwarte materiały edukacyjne.

  • Oxidation step in the preparation of benzocamalexin: The crystallographic evidence
    • Yordan Stremski
    • Anife Ahmedova
    • Anna Dołęga
    • Stela Statkova-Abeghe
    • Desislava Kirkova
    2021 MENDELEEV COMMUNICATIONS

    The study of oxidation step in the preparation of benzocamalexin by the α-amidoalkylation–oxidation sequence revealed the formation of perchloro-1,2-phenylene dibenzoate as the product of transformation of tetrachloro- 1,2-benzoquinone applied as the oxidant. The structures of benzocamalexin and perchloro-1,2-phenylene dibenzoate were confirmed by X-ray diffraction analysis. The extraction step in the final isolation of benzocamalexin is supposed to be crucial for the complete transformation of mono- and di- acylated perchloropyrocatechol.

  • Palm Oil Fuel Ash-Based Eco-Efficient Concrete: A Critical Review of the Short-Term Properties
    • Mugahed Amran
    • G. Murali
    • Roman Fediuk
    • Nikolai Vatin
    • Yuriy Vasilev
    • Hakim Abdelgader
    2021 Full text Materials

    The huge demand for concrete is predicted to upsurge due to rapid construction developments. Environmental worries regarding the large amounts of carbon dioxide emanations from cement production have resulted in new ideas to develop supplemental cementing materials, aiming to decrease the cement volume required for making concrete. Palm-oil-fuel-ash (POFA) is an industrial byproduct derived from palm oil waste’s incineration in power plants’ electricity generation. POFA has high pozzolanic characteristics. It is highly reactive and exhibits satisfactory micro-filling ability and unique properties. POFA is commonly used as a partially-alternated binder to Portland cement materials to make POFA-based eco-efficient concrete to build building using a green material. This paper presents a review of the material source, chemical composition, clean production and short-term properties of POFA. A review of related literature provides comprehensive insights into the potential application of POFA-based eco-efficient concrete in the construction industry today.

  • Paradoks decyzyjny – racjonalne i intuicyjne podejmowanie decyzji
    • Henryk Krawczyk
    2021

    W pracy scharakteryzowano poszczególne etapy działań prowadzące do znajdowania najlepszych rozwiązań dla rozpatrywanego problemu. Zwrócono uwagę na paradoks decyzyjny który wskazuje, że mądre rozwiązanie problemu wymaga zarówno racjonalnego, jak i intuicyjnego podejścia. Na przykładzie sortowania obrazów zaprezentowano niezależnie oba podejścia podkreślając potrzebę ich wzajemnego uzupełniania się. Podkreślono trudność budowy algorytmów, które będą uwzględniać jednocześnie te dwa odmienne podejścia. Prowadzi to do znalezienia rozwiązań nieoptymalnych, ale satysfakcjonujących wszystkich zainteresowanych. Pozwoli też na stopniowe wyjaśnianie ludzkiej mądrości i jej roli przy rozwiązywaniu życiowych problemów.

  • PARAMETRIC ANALYSIS OF THE EFFICIENCY OF THE COMBINED GAS-STEAM TURBINE UNIT OF A HYBRID CYCLE FOR THE FPSO VESSEL
    • Serhiy Serbin
    • Nikolay Washchilenko
    • Marek Dzida
    • Jerzy Kowalski
    2021 Full text Polish Maritime Research

    A thermal diagram of the combined gas‒steam turbine unit of a hybrid cycle, which is an energy complex consisting of a base gas turbine engine with a steam turbine heat recovery circuit and a steam-injected gas turbine operating with overexpansion, is proposed. A mathematical model of a power plant has been developed, taking into consideration the features of thermodynamic processes of simple, binary, and steam-injected gas‒steam cycles. Thermodynamic investigations and optimization of the parameters of a combined installation of a hybrid cycle for the generation of electrical energy have been carried out. Three-dimensional calculations of the combustion chamber of a steam-injected gas turbine were carried out, which confirmed the low emissions of the main toxic components.

  • Parseval Wavelet Frames on Riemannian Manifold
    • Marcin Bownik
    • Karol Dziedziul
    • Anna Kamont
    2021 Full text JOURNAL OF GEOMETRIC ANALYSIS

    We construct Parseval wavelet frames in L 2 (M) for a general Riemannian manifold M and we show the existence of wavelet unconditional frames in L p (M) for 1 < p < ∞. This is made possible thanks to smooth orthogonal projection decomposition of the identity operator on L 2 (M), which was recently proven by Bownik et al. (Potential Anal 54:41–94, 2021). We also show a characterization of Triebel–Lizorkin F sp,q (M) and Besov B sp,q (M) spaces on compact manifolds in terms of magnitudes of coefficients of Parseval wavelet frames. We achieve this by showing that Hestenes operators are bounded on F sp,q (M) and B sp,q (M) spaces on manifolds M with bounded geometry.

  • Partial inhibition of borohydride hydrolysis using porous activated carbon as an effective method to improve the electrocatalytic activity of the DBFC anode
    • Małgorzata Graś
    • Łukasz Kolanowski
    • Zhijie Chen
    • Katarzyna Lota
    • Kacper Jurak
    • Jacek Ryl
    • Bing-Jie Ni
    • Grzegorz Lota
    2021 Sustainable Energy & Fuels

    Carbon materials are commonly used catalyst supports in various types of fuel cells. Due to the possibility of designing their properties, they seem to be attractive and functional additives. In Direct Borohydride Fuel Cells (DBFCs), the electrooxidation reaction of borohydride competes with the undesirable hydrolysis reaction, therefore our work aimed to modify anodes based on a multi-component hydrogen storage alloy with a small number of activated carbons obtained from coffee waste to improve the hydrogen electrosorption properties. The produced activated carbons differed in terms of their physicochemical properties due to the different coffee waste-to-KOH ratio (1 : 1–1 : 4). Pressure measurements confirmed their effectiveness in relation to unconsumed hydrogen release, which initially hindered fuel diffusion. Nevertheless, it has been established that the addition of activated carbons improved the electrocatalytic activity of the anode, especially during cyclic operation (coulombic efficiency increased from 23% to 44% of the theoretical value). Moreover, X-ray photoelectron spectroscopy revealed that borohydride as a known reducing agent caused the reduction of oxygen functional groups on the carbon surface during DBFC operation, which made it possible to eliminate one of the factors influencing the BOR characteristics, and thus a more precise comparison of the analyzed activated carbons.

  • PAYMENT TRANSACTIONS’ ENERGY EFFICIENCY
    • Tetiana Osadcha
    • Oleksandr Melnychenko
    2021 Full text Współpraca Europejska

    The payment system and infrastructure is a sector that is not given enough attention today in the context of energy efficiency. This sector plays a big role in organizing and ensuring money circulation and funds. It has its value consisting on the one hand of the cost of payment equipment, infrastructure, payment instruments. On other hand, its value consists of the cost of energy for their manufacture and maintenance. The European Commission has proposed raising the target for reducing greenhouse gas emissions, including emissions and removals, to at least 55% by 2030 compared to 1990. The EU's ambitions to improve energy efficiency can be enhanced either by improving the energy efficiency of each sector or by improving some sectors more than others. And there are thousands upon thousands of areas in which energy efficiency can and should be improved: from matchmaking to, in fact, payment transactions. The payment system and money circulation seem to be not the biggest problems in the energy sector. However, this is a very delicate topic, because often people pay in supermarkets the money earned, buying food and basic necessities. They spend their energy in vain, waiting in line for a payment transaction. Modern means of payment and payment methods do not address the problem of reducing the time for servicing payments, which entails the overuse of time, energy, and money. And the latest method of payment using cryptocurrencies can not change the situation for the better today. The use of new and advanced technologies such as new generation data transmission systems, the use of modern computers' computing power, the replacement of means of payment with "faster" ones, the use of more efficient cashiers, or their replacement by functional machines can reduce these indicators.

  • Perfect thermal contact of hyperbolic conduction semispaces with an interfacial heat source
    • Oleksii Nosko
    2021 Full text INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER

    The problem of thermal contact between two bodies with a heat source at their interface presents great scientific and practical interest. On the time scale of a nanosecond or shorter, heat propagation should be considered in the form of thermal waves of finite speeds. This study investigated the thermal behaviour of hyperbolic conduction semispaces in perfect thermal contact subjected to the action of an interfacial heat source. An analytical solution was derived using the Laplace integral transform approach. The contact temperature and heat fluxes were analysed for different ratios of thermal conductivities K 1 and K 2 , thermal diffusivities k 1 and k 2 , and thermal relaxation times τ1 and τ2 of the semispaces. It was shown that the interfacial heat generation results in a step-wise change in the contact temperature. It was also found that the initial partition of heat between the semispaces occurs due to the ratio of K 1 / k 1 τ1 and K 2 / k 2 τ2 . The applicability of the obtained solution and its particular expressions was illustrated on the example of microscopic problems of ultra-short laser pulse welding and sliding friction.

  • Performance and Emission Modelling and Simulation of Marine Diesel Engines using Publicly Available Engine Data
    • Mohammad Ghaemi
    2021 Full text Polish Maritime Research

    To analyse the behaviour of marine diesel engines in unsteady states for different purposes, for example to determine the fuel consumption or emissions level, to adjust the control strategy, to manage the maintenance, etc., a goal-based mathematical model that can be easily implemented for simulation is necessary. Such a model usually requires a wide range of operating data, measured on a test stand. This is a time-consuming process with high costs and the relevant data are not available publicly for a selected engine. The present paper delivers a rapid and relatively simple method for preparing a simulation model of a given marine diesel engine, based only on the widely available data in the project guides indicated for steady state conditions. After establishing the framework of the mathematical model, it describes how the parameters of the model can be adjusted for the simulation model and how the results can be verified as well. Conceptually, this is a trial and error method, but the presented case example makes clear how the parameters can be selected to reduce the number of trials and quickly determine the model parameters. The necessary descriptions are given through a case study, which is the MAN-B&W 8S65ME-C8 marine diesel engine. The engine is assumed to be connected to a constant pitch propeller. The presented mathematical model is a mean-value zero-dimensional type with seven state variables. The other variables of the engine are determined based on the state independent variables and the input value, which is the fuel rate. The paper can be used as a guideline to prepare a convenient mathematical model for simulation, with the minimum publicly available data.

  • Performance Evaluation of GAM in Off-Body Path Loss Modelling for Body Area Networks
    • Michał Laskowski
    • Sławomir Ambroziak
    • Luis M. Correia
    • Krzysztof Świder
    2021 Full text

    This paper addresses the performance evaluation of an off-body path loss model, based on measurements at 2.45 GHz, which has been developed with the use of the Generalised Additive Model, allowing to model a non-linear dependence on different predictor variables. The model formulates path loss as a function of distance, antennas’ heights, antenna orientation angle and polarisation, results showing that performance is very sensitive to the orientation angle and to the polarisation of the transmitting and receiving antennas. Considering the model’s global performance, the obtained overall value of the adjusted coefficient of determination equals 0.60, while the mean error and the root mean square error equal 0 dB and 5.6 dB, respectively, which can be considered quite good for such a large diversity of addressed scenarios. One can then conclude that, regardless of the low performance of the method for some particular cases, the overall model accuracy may be considered good.

  • Performance Models of a Multidomain IMS/NGN Service Stratum
    • Sylwester Kaczmarek
    • Maciej Sac
    2021

    This paper quantifies call processing performance (CPP) of a multidomain IMS/NGN architecture, which was proposed to deliver current and future telecommunication services with strict quality requirements, independently of the transport network technologies. A realistic simulation model is used as a reference for evaluation of the analytical results, in which vari-ous types of queuing systems are applied to model the opera-tion of servers and links in a multidomain IMS/NGN. The compared results include mean Call Set-up Delay (E(CSD)) and mean Call Disengagement Delay (E(CDD)), a subset of standardized CPP parameters, which are very important for satisfaction of users and must be taken into account during network design. As a result, complete recommendations on queuing systems for a design process of a multidomain IMS/NGN are presented, given both accuracy and computation complexity.

  • Performance of a new commercial high-definition 3D patient specific quality assurance system for CyberKnife robotic radiotherapy and radiosurgery
    • Md Abdullah Al Kafi
    • Akram Al Moussa
    • Mohd Fahmi Mohd Yousof
    • Marek J. Maryański
    • Belal Moftah
    2021 RADIATION MEASUREMENTS

    Conventional two dimensional and low-definition measurement techniques for dosimetric verification of radiotherapy treatment deliveries are no longer adequate in the era of hypofractionation and extremely high dose gradients. New quality assurance (QA) tools with 3D capability and high definition are urgently needed. The purpose of this study was to evaluate the performance of one of the first such commercial systems as applied to CyberKnife (CK) radiotherapy/radiosurgery system. This study employed the recently developed commercial 3D patient-specific quality assurance (PSQA) system. Tissue-equivalent radiochromic polymer gel dosimeters, sealed in light protective thin-wall glass spheres (CrystalBalls), were mounted in a high-precision acrylic QA stand. Patient treatment plans were superimposed on the simulator CT scan of one selected CrystalBall and were irradiated in CK machine. CrystalBalls were then scanned using a laser CT scanner (OCTOPUS, MGS Research, Inc., DBA 3D Dosimetry, Madison, CT, USA). The simulator CT scan and the laser CT scan of the CrystalBall were registered in 6D using the VOLQA (MGS Research, Inc., DBA 3D Dosimetry, Madison, CT, USA) software. Planned and delivered dose distributions were compared by means of 3D gamma passing rates at user-selected acceptance criteria. Cumulative 3D dose-volume histograms and overlays of orthogonal profiles and isodoses both in 2D and in 3D were also generated, along with voxel statistics for dose difference and distance-to-agreement criteria. Twelve stereotactic radiosurgery/stereotactic radiotherapy/stereotactic body radiation therapy patients were selected randomly such that each set of two represented one of the six diagnoses: brain metastasis, trigeminal neuralgia, spine metastasis, prostate cancer, lung cancer and liver cancer. [...] The 3D gamma passing rate averaged over all patients studied was (90.5 ± 6.7) % at acceptance criteria of 2% (local) dose difference and 2 mm distance-to-agreement down to 20% isodose. For 3% (local) dose difference and 3 mm distance-to-agreement (also down to 20% cutoff dose), the average passing rate was (96.0 ± 3.1) %. The results of the study presented here form part of the information needed to assess suitability of a system and hence, the results suggest that the new high-definition 3D CrystalBall system can be a useful PSQA tool as a part of quality assurance for CK.

  • Performance of acicular grindable thermocouples for temperature measurements at sliding contacts
    • Oleksii Nosko
    • Wojciech Tarasiuk
    • Yurii Tsybrii
    • Andrey Nosko
    • Adolfo Senatore
    • Veronica D'Urso
    2021 Full text MEASUREMENT

    The present study investigates the performance of acicular grindable thermocouples based on a constantan wire / steel hollow cylinder construction. The experiments showed that the measuring junction electrical resistance, temperature–voltage characteristic, measuring junction rise time and signal noise standard deviation of the acicular thermocouples are comparable to those of conventional J-type thermocouples with bare wire diameter 0.25–0.5 mm. A pin-on-disc tribometer study of brake friction materials revealed that the acicular thermocouple involved in friction indicates up to 30% higher temperature than the contact temperature rise measured by infrared thermography. Another finding is that the infrared thermography contact temperature can be predicted with significantly higher accuracy by combining the acicular and conventional thermocouple techniques and taking the weighted sum of the respective temperatures.

  • Performance of Passive and Active Balancing Systems of Lithium Batteries in Onerous Mine Environment
    • Wojciech Kurpiel
    • Przemysław Deja
    • Bartosz Polnik
    • Marcin Skóra
    • Bogdan Miedziński
    • Marcin Habrych
    • Grzegorz Debita
    • Monika Zamłyńska
    • Przemysław Falkowski-Gilski
    2021 Full text ENERGIES

    To use lithium-iron-phosphate battery packs in the supply systems of any electric mining equipment and/or machines, the required conditions of work safety must be met. This applies in particular to coal mines endangered by fire and/or explosion. To meet the spark-safety conditions, the cells (together with the battery management system—BMS) must be isolated from the influence of the environment, and therefore placed in special fire-tight housings. This significantly degrades the heat dissipation, thus affecting the operating conditions of the cell-packs. Therefore, their usage without the so-called BMS is not recommended, as shown in the authors’ preliminary research. In practice, various BMS are used, most often with the so-called passive balancing. However, their application in mines is uncertain, due to the effect of heating under operation. When it comes to active BMS, they usually possess a quite complex structure and hence, are relatively expensive. Therefore, the authors conducted research for two specially developed active and one commercial passive BMS cooperating with selected lithium-iron-phosphate (LiFePO4) batteries when used in a suspended mining vehicle type PCA-1. The tests were carried out under environmental temperatures ranging from +5 °C to +60 °C. The effect of mismatching (12.5% to 37.5% of total cells number) of the cell parameters on the temperature distribution and voltage fading at the terminals of individual cells was checked. As a result of the investigations, the practical usefulness of the developed active BMS was determined, enabling the extension of the lithium-iron-phosphate battery life under onerous mine conditions, for a single recharge, which is a novelty. On the basis of the obtained results, appropriate practical conclusions were formulated.

  • Persistent homology as a new method of the assessment of heart rate variability
    • Grzegorz Graff
    • Beata Graff
    • Paweł Pilarczyk
    • Grzegorz Jabłoński
    • Dariusz Gąsecki
    • Krzysztof Narkiewicz
    2021 Full text PLOS ONE

    Heart rate variability (hrv) is a physiological phenomenon of the variation in the length of the time interval between consecutive heartbeats. In many cases it could be an indicator of the development of pathological states. The classical approach to the analysis of hrv includes time domain methods and frequency domain methods. However, attempts are still being made to define new and more effective hrv assessment tools. Persistent homology is a novel data analysis tool developed in the recent decades that is rooted at algebraic topology. The Topological Data Analysis (TDA) approach focuses on examining the shape of the data in terms of connectedness and holes, and has recently proved to be very effective in various fields of research. In this paper we propose the use of persistent homology to the hrv analysis. We recall selected topological descriptors used in the literature and we introduce some new topological descriptors that reflect the specificity of hrv, and we discuss their relation to the standard hrv measures. In particular, we show that this novel approach provides a collection of indices that might be at least as useful as the classical parameters in differentiating between series of beat-to-beat intervals (RR-intervals) in healthy subjects and patients suffering from a stroke episode.

  • Pervaporation in food processing
    • Roberto Castro-Muñoz
    • Grzegorz Boczkaj
    2021 Full text

    This chapter is about pervaporation in food processing

  • Pervaporation Zeolite-Based Composite Membranes for Solvent Separations
    • Roberto Castro-Muñoz
    • Grzegorz Boczkaj
    2021 Full text MOLECULES

    Thanks to their well-defined molecular sieving and stability, zeolites have been proposed in selective membrane separations, such as gas separation and pervaporation. For instance, the incorporation of zeolites into polymer phases to generate composite (or mixed matrix) membranes revealed important advances in pervaporation. Therefore, the goal of this review is to compile and elucidate the latest advances (over the last 2-3 years) of zeolite applications in pervaporation membranes either combining zeolites or polymers. Here, particular emphasis has been focused on relevant insights and findings in using zeolites in pervaporative azeotropic separations and specific aided applications, together with novel concepts of membranes. A brief background of the pervaporation process is also given. According to the findings of this review, we provide future perspectives and recommendations for new researchers in the field.