2021 - Publications Repository - Gdańsk University of Technology

Show publications from the year

Publications from the year 2021

Show all

Novel fast non-linear electrochemical impedance method for corrosion investigations
- Paweł Ślepski
- Michał Szociński
- Grzegorz Lentka
- Kazimierz Darowicki
2021 MEASUREMENT
The paper presents a novel approach to corrosion rate monitoring using non-linear electrochemical impedance spectroscopy. The authors propose a new variant of non-linear impedance measurement using amplitude-modulated multi-frequency ac perturbation signal. It allows shortening of measurement duration so it is possible to monitor corrosion rate of the systems experiencing rapid changes. In this way a limitation resulting from lack of stationarity condition during the impedance measurements is overcome. Potentialities of the proposed method were presented on the example of carbon steel corrosion in 1 M HCl solution. Sudden changes in the corrosion rate were induced by injection of urotropine as a corrosion inhibitor. The investigations provided time-evolution of charge transfer resistance and corrosion current, clearly reflecting the changes occurring in the investigated system triggered by the inhibitor introduction. Obtained corrosion current values were in a good agreement with the ones acquired using classic method of polarization in the Tafel range.
Novel hierarchical nonlinear control algorithm to improve dissolved oxygen control in biological WWTP
- Robert Piotrowski
- Hubert Sawicki
- Konrad Żuk
2021 Full text JOURNAL OF PROCESS CONTROL
Wastewater treatment is a problem known to humankind for centuries. The quality of treated sewage determines the condition of reservoirs around the world. Control of such a complex and nonlinear system as a wastewater treatment plant requires thorough knowledge of the process. The paper presents a hierarchical control system of a Sequencing Batch Reactor (SBR) in Wastewater Treatment Plant (WWTP) taking into account a model based on actual measurements taken from a WWTP in Swarzewo, Poland. The authors designed and implemented a nonlinear model predictive controller (MPC) that allows for the optimal implementation of the desired DO level while minimising the operation of actuators (aeration system). The design description of the predictive controller was associated with the need to specify the performance function and define the optimisation problem. In a two-layer structure, a supervisory controller was implemented based on an actual time-based controller in Swarzewo WWTP. The overview showed the improved performance of the treatment plant and the versatility of the created solution. Results of simulation tests for the wastewater treatment plant case study are presented.
Novel insights into conjugation of antitumor-active unsymmetrical bisacridine C-2028 with glutathione: characteristics of non-enzymatic and glutathione S-transferase-mediated reactions
- Agnieszka Potęga
- Michał Kosno
- Zofia Mazerska
2021 Full text Journal of Pharmaceutical Analysis
Unsymmetrical bisacridines (UAs) are a novel potent class of antitumor-active therapeutics. A significant route of phase II drug metabolism is conjugation with glutathione (GSH), which can be non-enzymatic and/or catalyzed by GSH-dependent enzymes. The aim of this work was to investigate the GSH-mediated metabolic pathway of a representative UA, C 2028. GSH supplemented incubations of C-2028 with rat, but not with human, liver cytosol led to the formation of a single GSH-related metabolite. Interestingly, it was also revealed with rat liver microsomes. Its formation was NADPH-independent and was not inhibited by co-incubation with the cytochrome P450 inhibitor 1-aminobenzotriazole. Therefore, the direct conjugation pathway occurred without the prior P450-catalyzed bioactivation of the substrate. In turn, incubations of C-2028 and GSH with human recombinant GSTP1-1 or with heat-/ethacrynic acid-inactivated liver cytosolic enzymes resulted in the presence or lack of GSH conjugated form, respectively. These findings proved the necessary participation of glutathione S-transferase (GST) in the initial activation of the GSH thiol group to enable a nucleophilic attack on the substrate molecule. Another C-2028-GSH S-conjugate was also formed during non-enzymatic reaction. Both GSH S-conjugates were characterized by combined liquid chromatography/tandem mass spectrometry. Mechanisms for their formation were proposed. The ability of C-2028 to GST mediated and/or direct GSH conjugation is suspected to be clinically important. This may affect the patient’s drug clearance due to GST activity, loss of GSH, or the interactions with GSH conjugated drugs. Moreover, GST mediated depletion of cellular GSH may increase tumor cell exposure to reactive products of UA metabolic transformations.
Novel luminescent calixarene-based lanthanide materials: From synthesis and characterization to the selective detection of Fe3+
- Ilária Martina Silva Lins
- José Daniel da Silva Fonseca
- Leonis Lourenço
- Jarosław Chojnacki
- Severino Júnior
- Bráulio Barros
- Joanna Kulesza
2021 JOURNAL OF SOLID STATE CHEMISTRY
Calix[n]arene-based coordination networks are an emerging class of materials with intriguing properties resulted from the presence of the cavity-like structure of the macrocycle and metallic nodes. In this work, four novel luminescent materials based on calix[4]arene-carboxylate and lanthanides (Eu3þ and Tb3þ) were prepared by two synthetic approaches, solvothermal (CDA-Eu-ST) and slow diffusion (CDA-Eu-RT, CDA-Tb-RT, CTA-Tb-complex) methods. The coordination networks were characterized by PXRD, FTIR, SEM and solid-state photoluminescence, and the results indicated the formation of two different CDA-Eu-structures governed by the synthesis parameters. Single-crystal X-ray diffraction of CTA-Tb-complex revealed the formation of a new dinuclear complex of calix[4] arene-tetracarboxylate containing Naþ and Tb3þ coordinated within the lower rim of the molecule. Preliminary studies showed that CDA-Eu-RT was capable of selectively sensing Fe3þ ions in water via quenching the luminescence, demonstrating the possibility of using calix[4]arene-based platforms as efficient luminescent sensors
Novel molecules containing structural features of NSAIDs and 1,2,3-triazole ring: Design, synthesis and evaluation as potential cytotoxic agents
- Jyoti Mareddy
- Kazi Hossain
- N. Sudhakar Yadav
- Venkanna Banothu
- Jaya Shree Anireddy
- Sarbani Pal
2021 Full text JOURNAL OF MOLECULAR STRUCTURE
For the first time the template containing structural features of more than one NSAIDs and the 1,2,3-triazole ring was explored for the identification of potential cytotoxic agents. These new and complex molecules were predicted to be effective inhibitors of PDE4B by molecular modelling studies in silico. The multi-step synthesis of these compounds were carried out starting from the well-known drug nimesulide and involved the use of coppercatalyzed azide-alkyne cycloaddition (CuAAC) approach as the key step. Mainly two types of compounds e.g. 1- aryl-1H-1,2,3-triazoles and N-aryl-2-(1H-1,2,3-triazol-1-yl)acetamide derivatives were synthesized by using this method in good yields. The in vitro screening of these compounds against two cancer cell lines e.g. HCT-15 (human colon cancer cell line) and NCI-H226 (human lung cancer cell line) using a colorimetric MTT assay allowed identification of two preliminary hit molecules i.e. 8a and 8f. The SAR (Structure Activity Relationship) analysis indicated that the presence of an amide linker between the aryl ring and the 1,2,3-triazole moiety was favorable for the activities. The compound 8a and 8f showed significant inhibition of PDE4B in vitro and good interactions with this protein in silico suggesting PDE4B as their potential target. The usefulness and concerns of these molecules in the light of computational ADME prediction were analyzed. Overall, novel molecules were identified as potential cytotoxic agents for further study.
Novel Research on Biomedical Polyurethanes
- Józef Haponiuk
- Justyna Kucińska-Lipka
- Paweł Szarlej
- Przemysław Gnatowski
2021
The variety of mechanical properties characterizes properly designed PURs. They may be biocompatible and reveal compatibility with blood, making them attractive materials for the fabrication of tissue scaffolds; however, like all synthetic materials, PURs don’t reveal sufficient biocompatibility. PURs may undergo certain chemical modifications (e.g., 1,4:3,6-dianhydro-D-sorbitol, ascorbic acid (AA), growth factors, covering with gelatin, plasma modifications to impart them the bioactivity. In the regeneration of soft and hard tissues, as well as in cardiovascular system regeneration, more common have become the scaffolds - three-dimensional (3D), porous structures, which are biological substitutes enabling for regeneration, maintenance, and improvement of tissues functions representing mechanical properties suitable to support regenerated tissue. Moreover, in specific applications, it is required that such material, after application to the human body, undergo gradual degradation, at a rate directly proportional to the growth of the reconstructed tissue, and the degradation products cannot be harmful and toxic for the system. The tissue scaffolds degradation rate, according to the literature, has to be controlled in a way that the tissue scaffold maintains its physicochemical and mechanical properties for at least 3-6 months. Searching for new materials of described characteristic lead me to undertake the design of new PUR systems, which will be undergoing degradation and at the same time will be biocompatible and of physicochemical, mechanical, and thermal properties suitable for this purpose. In the literature was reported an application of aromatic diisocyanates for PUR synthesis, which are used for the fabrication of tissue scaffolds. Such materials, after long-term in vitro interaction with the living tissues, undergo degradation to the harmful for the living system aromatic diamines. In performed studies, we have applied aliphatic and cycloaliphatic diisocyanates (1,6-hexamethylene diisocyanate (HDI) and 4,4’-methylene bis(cyclohexyl isocyanate) (HMDI), which degradation products (in the living system) are nontoxic amines removable from the system in natural life cycles .In our research we were using an amorphous α,ω-dihydroxy(ethylene-butylene adipate) macrodiol (PEBA) to improve the degradation behavior of PURs and tissue scaffolds fabricated with their use, and we proposed modificators of their biological properties.
Novel staphylococci nucH taxonomical marker used in identification of human-associated Staphylococcus succinus subsp. casei
- Katarzyna Garbacz
- Roman Kotłowski
- Ewa Kwapisz
2021 Environmental Microbiology Reports
The aim of our study was to assess the sequencing of unique nucH gene fragment based on performed bioinformatics analysis as a novel diagnostic method for the identification of difficult to identify staphylococcal human pathogenic strains. Initially, PCR-RFLP-rrn analysis specific to the spacers between 16SrDNA and 23SrDNA followed by HhaI restriction analysis was performed. Further, sequencing of nucH and 16S rDNA genes fragments was carried out. Blast analysis from the NCBI showed 99% similarity of nucH gene fragment with reference genomic DNA for S. succinus with the accession no. CP018199. This result was also confirmed by MALDI-TOF analysis. Sequencing analysis of 16S rDNA gene fragment allowed for 100% identification of two strains isolated from human samples as Staphylococus succinus subsp. casei. Sequencing of identified unique nucH gene fragment seems to be a promising diagnostic assay for the identification of Staphylococcus species. Based on our results, we can assume that probably other Staphylococcus species originated from different clinical samples could be identified using nucH gene sequencing method we developed. However, an extension of the genetic databases with a substantially bigger number of reference staphylococcal species for nucH gene is needed to make this method better than widely used standard 16S rDNA sequencing assay. To the best of our knowledge, it is the second published isolation of S. succinus subsp. casei from human clinical specimens. Moreover, possibility of decreasing the number of dimensions from multi-PCR-bands results using ribotyping analysis is also described.
Novel strategies to enhance hydrodynamic cavitation in a circular venturi using RANS numerical simulations
- Nilanjan Dutta
- Prasad Kopparthi
- Asim Kumar Mukherjee
- Neelkanth Nirmalkar
- Grzegorz Boczkaj
2021 WATER RESEARCH
Hydrodynamic cavitation is a popular advanced oxidation technique and it has received wide range of applications from waste water treatment to the nanoparticles synthesis in recent years. The enhancement of the intensity of the hydrodynamic cavitation is always been an emerging field of research. Within this framework, we have proposed and investigated three distinct strategies to enhance the intensity of cavitation in a circular venturi, namely, (1) by introducing the surface roughness on the wall (2) single or multiple circular hurdles in the diverging section (3) By modifying the diverging section from planer to the trumpet shape. RANS (Reynolds Averaged Navier-Stokes) based numerical simulations are carried out the over wide range of conditions: (pressure ratio), (half divergent angle), (half convergent angle), and (throat length). An extensive numerical and experimental validation with the literature have been presented to ensure the reliability and accuracy of present work. Detailed results on velocity fields, local and average volume fraction, pressure loss coefficients, cavitation number, discharge coefficient and pressure distribution are reported as function of dimensionless parameters. Five designs of various combinations of surface roughness, circular hurdles, and trumpet diverging section have been compared. The effect of surface roughness on trumpet diverging wall has been observed to be more pronounced than the other designs. Trumpet diverging wall with surface roughness is found to be optimum for the practical applications.
Novel Structures and Applications of Graphene-Based Semiconductor Photocatalysts: Faceted Particles, Photonic Crystals, Antimicrobial and Magnetic Properties
- Marcin Janaczek
- Maya Endo-Kimura
- Zhishun Wei
- Zuzanna Bielan
- Tharishinny R. Mogan
- Tamer M. Khedr
- Kunlei Wang
- A. Markowska-Szczupak
- Kowalska Ewa
- Agata Markowska-Szczupak
2021 Full text Applied Sciences
Graphene, graphene oxide, reduced graphene oxide and their composites with various compounds/materials have high potential for substantial impact as cheap photocatalysts, which is essential to meet the demands of global activity, offering the advantage of utilizing “green” solar energy. Accordingly, graphene-based materials might help to reduce reliance on fossil fuel supplies and facile remediation routes to achieve clean environment and pure water. This review presents recent developments of graphene-based semiconductor photocatalysts, including novel composites with faceted particles, photonic crystals, and nanotubes/nanowires, where the enhancement of activity mechanism is associated with a synergistic effect resulting from the presence of graphene structure. Moreover, antimicrobial potential (highly needed these days), and facile recovery/reuse of photocatalysts by magnetic field have been addresses as very important issue for future commercialization. It is believed that graphene materials should be available soon in the market, especially because of constantly decreasing prices of graphene, vis response, excellent charge transfer ability, and thus high and broad photocatalytic activity against both organic pollutants and microorganisms.
Novel two-step synthesis method of thin film heterojunction of BiOBr/Bi2WO6 with improved visible-light-driven photocatalytic activity
- Anna Pancielejko
- Justyna Łuczak
- Wojciech Lisowski
- Adriana Zaleska-Medynska
- Paweł Mazierski
2021 Full text APPLIED SURFACE SCIENCE
A novel two-step ionic liquid assisted procedure was applied for a controllable synthesis of BiOBr/Bi2WO6 heterojunction thin films. The preparation route involved an anodic oxidation of tungsten foil and hydrothermal transformation of as-anodized oxide in the presence of bismuth precursor and ionic liquid, N-butylpyridinium bromide [BPy][Br]. The BiOBr plates with irregular shapes adhered to the surface of flower-like Bi2WO6 and formed a heterojunction between BiOBr and Bi2WO6, as confirmed by the analysis of their structure and composition. The highest efficiency of phenol degradation was achieved when the highest amount of IL was used (the apparent quantum efficiency was almost 8 and 71.5 times higher compared to BiOBr and Bi2WO6, respectively). In addition, superoxide radicals (•O2–) were found as the main factor responsible for the photodegradation. A possible reaction mechanism was further investigated as a function of monochromatic irradiation to determine the exact range of the composite photoactivity.
Nowe kierunki usuwania azotu w oczyszczalniach ścieków
- Dominika Sobotka
- Katarzyna Hrynkiewicz
- Marcin Marcinkowski
- Joanna Majtacz
- Dominika Grubba
- Jacek Mąkinia
2021 Forum Eksploatatora
W 2015 roku Komisja Europejska przyjęła nową strategię gospodarki o obiegu zamkniętym (ang. Circular Economy), której celem jest efektywne wykorzystanie zasobów, a także zwiększenie roli gospodarki odpadami. Działania prowadzone w ostatnich latach w sektorze oczyszczania ścieków były ukierunkowane na rozwój efektywnej, niskoemisyjnej gospodarki zasobami, sprzyjającej wzrostowi bezpieczeństwa energetycznego i poprawie stanu jakości wód. Działania te spowodowały zmianę paradygmatu, zgodnie z którym ścieki, zarówno komunalne jak i powstające w trakcie procesów produkcyjnych, traktowane są jako źródło energii i surowców, takich jak woda, biogeny czy związki organiczne.
Nowe sposoby instrumentalnego określania wybranych cech zapachu za pomocą technik czujnikowych
- Bartosz Szulczyński
2021 Full text
Rozprawa doktorska zawiera opis rozwoju nowych metod instrumentalnego określania wybranych cech zapachu za pomocą technik czujnikowych (elektronicznych nosów). Jest ona oparta na sześciu artykułach opublikowanych w recenzowanych czasopismach naukowych. Głównym celem tej pracy było określenie możliwości wykorzystania elektronicznego nosa do instrumentalizacji pomiaru wybranych cech zapachu – intensywności i jakości hedonicznej, z uwzględnieniem występujących w badanych mieszaninach interakcji zapachowych. Badania prowadzono z wykorzystaniem samodzielnie zaprojektowanych i skonstruowanych prototypów elektronicznych nosów, a uzyskane wyniki porównywano z wynikami analizy sensorycznej oraz wartościami teoretycznymi obliczonymi z wykorzystaniem modeli percepcyjnych i psychofizycznych. Jako metody analizy danych stosowano regresję głównych składowych, sztuczne sieci neuronowe oraz logikę rozmytą. Zastosowanie tych metod pozwoliło również określać interakcje zapachowe występujące w badanych próbkach, które pokrywają się w ponad 75% ze wskazaniami panelu sensorycznego. Opracowaną sztuczną sieć neuronową wykorzystano do monitorowania procesu dezodoryzacji powietrza metodą biofiltracji ze złożem zraszanym.
Nowe technologie w procesie projektowania architektonicznego
- Jan Cudzik
2021 Zawód: Architekt
Projektowanie architektoniczne zmienia się wraz z wprowadzaniem nowych technologii. Zmiany, które są wynikiem cyfrowej rewolucji z końca XX wieku przyczyniły się do zmiany metod stosowanych w projektowaniu, ale nie sposobu myślenia o projektach i ich etapach. Można stwierdzić, że tradycyjna deska kreślarska została zastąpiona cyfrową. Jednak dziś w związku ze wzrostem skomplikowania procesów projektowych, ich wielowarstwowości oraz rosnącymi możliwościami komputacyjnymi, możemy projektować bardziej efektywnie i dokładnie. Badacz architektury cyfrowej Wasim Jabi zauważa, że projektowanie jest z natury rzeczy iteracyjne, każda nowa tura stawie pytania i odpowiedzi, na które wpływają później na uzyskiwany efekt przestrzenny. Ciągłe modyfikowanie projektu jest więc konieczne, a bez zastosowania form automatyzacji w projekcie jest to czasochłonne i często przyczynia się do powstawania błędów. Co więcej, im bardziej zaawansowany projekt i jego etap, tym czas konieczny na zmiany oraz prawdopodobieństwo wystąpienia błędu znacząco wzrasta. Projekt zbudowany o zasady algorytmiczne pozwala na wprowadzanie dowolnych zmian w projekcie na każdym etapie jego tworzenia bez konieczności ręcznego przerysowywania, czy modelowania każdej z jego wersji. Powyższe zmiany zachodzące w architekturze są zauważalne na różnych etapach procesu projektowego, a ich skalę dekadę temu potrafiło ocenić niewielu. Dziś ta świadomość jest już większa, ale z uwagi na ciągły rozwój narzędzi wymaga ciągłej nauki i otwartości.
Numerical and experimental study on effect of boundary conditions during testing of stiffened plates subjected to compressive loads
- Krzysztof Wołoszyk
- Yordan Garbatov
- Jakub Kowalski
- Leszek Samson
2021 Full text ENGINEERING STRUCTURES
This study analyses the effect of boundary conditions during testing on the structural behaviour stiffened plates with different thicknesses subjected to compressive loads. The goal of the compressive tests is to analyse the ultimate strength of a stiffened plate. During the test, relevant physical quantities are measured and investigated. The supporting structure's behaviour is investigated by analysing the force-displacements relationship and post-collapse shapes of tested specimens. The experimental results are compared with the ones made by FE analyses. The FE model is explored in two variants, considering clamped and simply supported boundary conditions. A detailed comparison of the lateral deflections of plates near the supports is also performed. The analysis has shown that nearly clamped boundary conditions were achieved during the test, leading to an almost complete restriction of plate rotations during the experimental testing, which complies with the real ship structural behaviour of similar components when deep girders transversally support them.
Numerical Estimation of Hull Hydrodynamic Derivatives in Ship Maneuvering Prediction
- Radosław Kołodziej
- Paweł Hoffmann
2021 Full text Polish Maritime Research
Prediction of the maneuvering characteristics of the ship at the design stage can be done by means of model tests, computational simulations or a combination of both. The model tests can be realized as direct simulation of the standard maneuvers with the free running model, which gives the most accurate results, but is also the least affordable as it requires very large tank or natural lake, as well as complex equipment of the model. Alternatively, captive model test can be used to identify the hydrodynamic characteristics of the hull which can be used to simulate the standard maneuvers with the use of dedicated software. Two types of captive model tests are distinguished: circular motion tests (CMT) and planar motion mechanism tests (PMM). The paper presents an attempt on developing computational method for ship maneuverability prediction in which the hydrodynamic characteristics of the hull are identified by means of computational fluid dynamics (CFD). The CFD analyses presented here simulate directly the circular motion test. The resulting hull characteristics are verified against the available literature data, and the results of the simulations are verified against the results of free running model tests. Reasonable agreement shows large potential of the proposed method.
NUMERICAL ESTIMATION OF HULL HYDRODYNAMIC DERIVATIVES IN SHIP MANOUVERING PREDICTION
- Radosław Kołodziej
- Paweł Hoffmann
2021
Operating in crowded waterways pose a risk of accidents and disasters due to maneuvering limitations of the ship. In order to predict ship’s maneuvering characteristics at the design stage, model tests are often executed as the most accurate prediction tool. Two approaches can be distinguished here: free running model tests and numerical simulations based on planar motion model with the use of hydrodynamic derivatives obtained from captive model tests. However, although the model tests give very accurate prediction of ship’s maneuvering performance, they are often not affordable both due to the cost and due to their duration, making them less efficient in iterative design process. Thus, CFD simulations became one of the most commonly used research methods in ship hydrodynamics, offering reasonable compromise between the accuracy and the cost. Along with continuously improving computing power and increasingly accurate numerical methods, it became possible to develop new ways of assessing ship maneuvering performance with the use state of the art CFD tools. The purpose of this paper is to present one of such methods which is established for practical use in design process of a ship. The analysis is focused on evaluation of hydrodynamic derivatives for the hull based on CFD simulation equivalent to the rotating arm test - one of the variants of captive tests. The results are verified versus the results of model tests carried out in Maritime Advanced Research Centre CTO S.A. with the use of planar motion mechanism - PMM.
Numerical evaluation of dynamic response of an experimentally tested base-isolated and fixed-base steel structure model
- Tomasz Falborski
- Tomasz Jaroszewski
- Robert Jankowski
2021 Full text
Seismic isolation is recognized as one of the most popular and effective methods of protecting structures during earthquake. The present paper is focused on the comparison be-tween the dynamic responses of buildings with fixed and isolated bases exposed to seismic exci-tations. The aim of the study is to investigate the effectiveness of a simplified base isolation numerical modelling technique using the linear springs. One-storey steel structure model has been considered using ETABS software, which was previously tested during the shaking table tests. The comparison of the structural response has been performed between the numerical and experimental results. High compatibility of the results for the fixed-base steel model between the numerical and experimental analyses has been obtained which proves the effectiveness of the modelling techniques used in the ETABS software. It has also been found that the isolation system is effective in improving the response of the steel structure during earthquake. However, modelling the isolation system using the linear springs is not an accurate technique due to the large differences in the structural responses obtained between the numerical and experimental analyses.
Numerical investigation on distribution characteristics of oxidation air in a lime slurry desulfurization system with rotary jet agitators
- Longhao Xiang
- Xun Sun
- Xuesong Wei
- Guichao Wang
- Grzegorz Boczkaj
- Joon Yong Yoon
- Songying Chen
2021 Full text CHEMICAL ENGINEERING AND PROCESSING
Rotary jet agitator is an effective device for mixing, dispersing, dissolving, and suspending dispersed phases in liquid, and is particularly advantageous to the homogenization of oxygen-enriched air within the lime slurry desulfurization system. The distribution of oxygen-enriched air in agitators is vital for the process of gypsum crystallization and the homogeneous and sufficient oxygen-enriched air can promote the formation of an economically useful by-product. The present study investigated the diffusion performance of oxygen-enriched air in a rotary jet agitator during the wet flue gas desulfurization process by utilizing computational fluid dynamics. The consistency of numerical and experimental results is validated under identical conditions. Investigation results show that the rotation velocities and the inlet velocities of rotary jet machines significantly affect the distribution and homogeneity of the oxygen-enriched air distribution. However, these effects deteriorate with increasing rotation angular and jet outlet velocities. Under the optimal condition, the oxygen-enriched air concentration, within the cross-sections, fluctuates by approximately 20%. The Rotary jet agitator appears to be a remarkable method for the homogenization of oxygen-enriched air in the lime slurry tank, and in other gas-liquid stirring tanks, due to its high efficacy and good stirring effect.
Numerical Model of Surface and Quasi-Spherical Sea Noise and Its Application to Analysis of DIFAR Systems
- Mariusz Rudnicki
- Roman Salamon
- Jacek Marszal
2021 Full text Archives of Acoustics
Various types of passive sonar systems are used to detect submarines. These activities are complex and demanding. Therefore, computer simulations are most often used at the design stage of these systems. For this reason, it is also necessary to simulate the acoustic ambient noise of the sea. The article proposes a new numerical model of surface and quasi-spherical sea noise and presents its statistical parameters. The results of the application of the developed noise model to analyse the received signals of the DIFAR1 sonobuoy are also presented.
Numerical Model of the Aortic Valve Implanted Within Real Human Aorta
- Marcin Nowak
- Wojciech Adamczyk
- Bartlomiej Melka
- Ziemowit Ostrowski
- Ryszard Bialecki
2021
Cardiovascular system diseases are the main cause of deaths in developed and developing countries. The main reasons are myocardial infarction, heart failure, stroke and valvular diseases. These are caused mainly by arteriosclerosis. The valvular diseases involve a significant burden for the health care system and their frequency is rising with the patient age. This work describes the tools and numerical models appropriate for modeling the blood flow through the synthetic aortic valve and demonstrates the preliminary model used by authors. The overset mesh technique was applied to capture synthetic valve movement implanted within the aortic root, the aorta arch and the main branches of cardiovascular system. As the analyzed geometry scope does not include the whole cardiovascular system, there are artificial boundaries present at the inlet and at the outlets. To capture the cardiac system influence on the pressure values at these boundaries, the lumped parameter model was implemented.