2023 - Repozytorium publikacji - Politechnika Gdańska

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The use of Preston equation to determine material removal during lap-grinding with electroplated CBN tools
- Mariusz Deja
2023 Pełny tekst WEAR
Grinding executed in a lapping configuration is an alternative finishing process benefiting from both grinding and free-abrasive machining, while minimizing the heat effect impact. Electroplated tools can be effectively used in different abrasive processes, including high-speed grinding, however, the assessment of machining performance over time is a key factor in their correct use to achieve satisfactory technological results. In conventional grinding, bigger grain-coverage provides better results due to the higher bonding strength of grains. In lap- grinding, fracturing and crushing of the abrasive particles initially covered by the plating result in a suspension which is typically dosed continuously in free-abrasive machining. Due to this, the process transforms from two-body (grinding) to three-body abrasion (free abrasive machining) which may result in reduced grinding performance approaching asymptotically a specific value while improving surface finish. The main aim of the presented study is the evaluation of electroplated CBN tools used in lap-grinding of 40H alloy steel workpieces whose hardness was 54 HRC. The obtained results and observations of the working surface of CBN wheels and workpieces allowed for the identification of the wear characteristics for three nickel plating thicknesses corresponding to 35%, 50% and 65% of the nominal CBN crystal size and for specific process parameters. The surface roughness Ra parameter decreased gradually from the initial value 1.9 μm to the values below 0.7 μm for bigger B107 grains and for all plating thicknesses. For smaller B64 grains, the surface roughness and waviness parameters reached similar values to those obtained for the larger B107 grains at corresponding processing times. The lowest value of Ra parameter below 0.4 μm was obtained for B64 grains and for the thinnest plating but with a 50% reduction in material removal comparing to B107 grains. The Preston equation was employed to calculate the material removal as a function of time under variable process conditions in the machining zone due to the tool wear. This attempt extended the range of the material removal modeling, despite the fact that the electroplated wheels were subject to wearing down resulting in the gradual reduction in the efficiency, as well as in the change of the working conditions in the workpiece-tool contact zone.
Theoretical analysis and experimental tests of tilting pad journal bearings with shoes made of polymer material and low-boiling liquid lubrication
- Grzegorz Żywica
- Artur Olszewski
- Paweł Bagiński
- Artur Andrearczyk
- Tomasz Żochowski
- Piotr Klonowicz
2023 Pełny tekst TRIBOLOGY INTERNATIONAL
Selecting the appropriate bearing system for the rotor requires a good knowledge of the available solutions and the operating conditions of the machine. For newly designed machinery operating in adverse conditions, selecting bearings that ensure correct and long-lasting operation can be extremely challenging. Difficulties in- crease when the machine’s operating parameters are beyond the technical capabilities of available technical solutions. This article presents the course of the design process and results of numerical and experimental research of a prototype microturbine that uses an innovative rotor-bearing system. Due to the adverse operating conditions, new tilting pad journal bearings were designed, in which the sliding surfaces of the tilting pads were made of polymeric material and a low-viscosity medium in liquid form was used as the lubricating medium. The basic bearing parameters were selected and pre-checked by numerical calculations. The oil-free turbomachinery design thus developed was subjected to experimental testing under near-real conditions. The results of these tests confirmed that the developed bearings performed very well, ensuring stable operation of the high-speed rotor of the microturbine over a wide speed range. Despite the unfavourable lubrication conditions, no signs of bearing wear were observed. The results obtained indicate a new, promising direction for the development of bearing systems for turbomachinery, in which, with a suitable design of the bearings, a low-boiling working medium in liquid form can be used as a lubricating medium.
Theoretical and experimental analysis of guided wave propagation in plate-like structures with sinusoidal thickness variations
- Beata Zima
- Jochen Moll
2023 Pełny tekst Archives of Civil and Mechanical Engineering
Guided waves have attracted significant attention for non-destructive testing (NDT) and structural health monitoring (SHM) due to their ability to travel relatively long distances without significant energy loss combined with their sensitivity to even small defects. Therefore, they are commonly used in damage detection and localization applications. The main idea of incorporating guided waves in NDT and SHM is based on processing the received signals and appropriate interpretation of their characteristics. A great amount of research devoted to diagnostics of plate-like structures considers specimens with constant thickness, which significantly facilities the diagnostic process. In such a case the velocity is also assumed to be constant. However, the developed diagnostic methods should be applicable, especially for the structures exposed to an aggressive environment, excessive load, or unfavorable weather conditions, etc., when the probability of damage occurring is much higher. In such cases, the assumption about the uniform thickness alongside the propagation path cannot be applied in every case. Thus, the present study is focused on wave propagation in metallic plates with variable thickness. The results of theoretical, numerical and experimental investigations of antisymmetric Lamb mode propagation in aluminum plates with a sine-shaped surface are presented. In the first step, the influence of non-uniform thickness distribution on wave velocity has been described. Next, the inverse problem aimed at shape reconstruction based on time of flight (ToF) analysis and spatially varying wave velocity was solved and compared with the standard dispersion curve-fitting method.
Therapeutic biomaterials - application in neurology and cardiology
- Klaudia Malisz
- Beata Świeczko-Żurek
2023
Biomaterials are of interest in most medical fields. It's hard to imagine life without them. And due to the ever-increasing demand, scientists are developing new materials. Diseases of the nervous and cardiovascular systems are still a big problem, which are associated with a limited ability to regenerate brain or heart tissues. Therefore, this review discusses the advancement in biomaterial engineering for the treatment of neurological and cardiovascular diseases. Neurodegenerative diseases affect a large percentage of older people. Therefore, the review presents treatment options for Alzheimer's (AD), and Parkinson's diseases (PD). Another serious problem is cardiac ischemia. To regenerate heart tissue, scientists have proposed the use of extracellular vesicles, injectable hydrogels, and biomaterial-based cardiac patches. In addition to tissue engineering, implants are also developing in the field of cardiology. More and more modern materials are being created, e.g., for valve prostheses or vascular stents.
Thermal analysis of Magnetohydrodynamics (MHD) Casson fluid with suspended Iron (II, III) oxide-aluminum oxide-titanium dioxide ternary-hybrid nanostructures
- Hajra Kaneez
- Awab Baqar
- Irum Andleeb
- Muhammad Bilal Hafeez
- Marek Krawczuk
- Wasim Jamshed
- Mohamed Eid
- Assmaa Abd-elmonem Assmaa
2023 JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
This study is carried out to enhance and analyze the thermal performance of non-Newtonian Casson fluid by immersing Ternary hybrid nanoparticles Fe3O4-Al2O3-TiO2 uniformly. To model the behaviour of such complex phenomena mathematically, a system of complex transport differential equations is developed by utilizing a non-Fourier heat transfer model for energy transport. The non-dimensional system of transport equations involving physical parameters is analyzed numerically by employing the Galerkin finite element methodology (G-FEM). The simulations predicted promising enhanced heat transfer characteristics in Ternary hybrid Casson fluid. The Casson fluid parameter has shown remarkable behavior on temperature distribution. Ternary hybrid nanoparticles have increased the overall thermal conductivity of the fluid and consequently, the temperature distribution is significantly raised. Hence ternary hybridity of nano-structures in Casson fluid is shown as an effective technique in improving the thermal performance of complex fluid.
Thermal Energy Storage with PCMs in Shell-and-Tube Units: A Review
- Janusz Cieśliński
- Maciej Fabrykiewicz
2023 Pełny tekst ENERGIES
The paper presents a survey of the experimental and numerical studies of shell-and-tube systems in which phase change material (PCM) is used. Due to the multitude of design solutions for shell-and-tube systems, the emphasis is placed on double-tube (DT), triplex-tube (TT), and multitube (MT) units. Additionally, only single-pass systems are considered. Particular attention is paid to the method of heat transfer intensification. The analysis of the research results begins with the classification of each of the three mentioned systems. The systems are divided according to the angle of inclination, the method of heat transfer enhancement (HTE), the flow direction of heat transfer fluid (HTF), and the arrangement of tubes in the bundle. Moreover, the simplified schemes of the particular research cases are proposed. Then, the works on each of the mentioned systems, i.e., DT, TT, and MT, are discussed chronologically. Finally, in the corresponding tables, details of the discussed cases are presented, such as geometric dimensions, and the type of PCM or HTF used. A novelty in the present work is the precise classification of PCM TESUs as DT, TTH, and MTH. In the literature, there is a lot of discretion in this regard. Second, the methods of heat transfer intensification in the presented PCM TESUs are listed and discussed. Third, unified schemes of design solutions for the discussed PCM TESUs are proposed. The review shows that development directions for shell-and-tube TESUs include systems with high conductivity fins of different shapes, heights, and spacing, several PCMs, and modified shells.
Thermal Image Processing for Respiratory Estimation from Cubical Data with Expandable Depth
- Maciej Szankin
- Alicja Kwaśniewska
- Jacek Rumiński
2023 Pełny tekst Journal of Imaging
As healthcare costs continue to rise, finding affordable and non-invasive ways to monitor vital signs is increasingly important. One of the key metrics for assessing overall health and identifying potential issues early on is respiratory rate (RR). Most of the existing methods require multiple steps that consist of image and signal processing. This might be difficult to deploy on edge devices that often do not have specialized digital signal processors (DSP). Therefore, the goal of this study is to develop a single neural network realizing the entire process of RR estimation in a single forward pass. The proposed solution builds on recent advances in video recognition, capturing both spatial and temporal information in a multi-path network. Both paths process the data at different sampling rates to capture rapid and slow changes that are associated with differences in the temperature of the nostril area during the breathing episodes. The preliminary results show that the introduced end-to-end solution achieves better performance compared to state-of-the-art methods, without requiring additional pre/post-processing steps and signal-processing techniques. In addition, the presented results demonstrate its robustness on low-resolution thermal video sequences that are often used at the embedded edge due to the size and power constraints of such systems. Taking that into account, the proposed approach has the potential for efficient and convenient respiratory rate estimation across various markets in solutions deployed locally, close to end users.
Thermal Instability of Gold Thin Films
- Marcin Łapiński
- Piotr Dróżdż
- Mariusz Gołębiowski
- Piotr Okoczuk
- Jakub Karczewski
- Marta Sobanska
- Aleksiej Pietruczik
- Zbigniew R. Zytkiewicz
- Ryszard Zdyb
- Wojciech Sadowski
- Barbara Kościelska
2023 Pełny tekst Coatings
The disintegration of a continuous metallic thin film leads to the formation of isolated islands, which can be used for the preparation of plasmonic structures. The transformation mechanism is driven by a thermally accelerated diffusion that leads to the minimalization of surface free energy in the system. In this paper, we report the results of our study on the disintegration of gold thin film and the formation of nanoislands on silicon substrates, both pure and with native silicon dioxide film. To study the processes leading to the formation of gold nanostructures and to investigate the effect of the oxide layer on silicon diffusion, metallic film with a thickness of 3 nm was deposited by molecular beam epitaxy (MBE) technique on both pure and oxidized silicon substrates. Transformation of the thin film was observed by low-energy electron microscopy (LEEM) and a scanning electron microscope (SEM), while the nanostructures formed were observed by atomic force microscope (AFM) method. Structural investigations were performed by low-energy electron diffraction (LEED) and X-ray photoelectron spectroscopy (XPS) methods. Our experiments confirmed a strong correlation between the formation of nanoislands and the presence of native oxide on silicon substrates.
Thermomagnetic behavior of a semiconductor material heated by pulsed excitation based on the fourth-order MGT photothermal model
- Ahmed Abouelregal
- Hamid M. Sedighi
- Victor Eremeev
2023 Pełny tekst CONTINUUM MECHANICS AND THERMODYNAMICS
This article proposes a photothermal model to reveal the thermo-magneto-mechanical properties of semiconductor materials, including coupled diffusion equations for thermal conductivity, elasticity, and excess carrier density. The proposed model is developed to account for the optical heating that occurs through the semiconductor medium. The Moore–Gibson–Thompson (MGT) equation of the fourth-order serves as the theoretical framework to establish the photothermal model. It is well-known that the optical and heat transfer properties of such materials behave as random functions of photoexcited-carrier density; therefore, the current model is remarkably more reliable compared to the earlier closed-form theories which are limited to a single form. The constructed theoretical framework is able to investigate the magneto-photo-thermoelastic problems in a semiconductor medium due to laser pulse excitation as a case study. Some parametric studies are used to exhibit the impact of thermal parameters, electromagnetic fields, laser pulses and thermoelectric coupling factors on the thermomagnetic behavior of physical variables. Finally, several numerical examples have been presented to draw the distributions of the examined field variables.
thestats: An Open-Data R Package for Exploring Turkish Higher Education Statistics
- Mustafa Cavus
- Olgun Aydin
2023 Pełny tekst Yuksekogretim Dergisi
There are open datasets available for official statistics, finance, education, and a variety of other domains. The open datasets are published by third-party vendors as well as official authorities. For example, The Turkish Higher Education Council maintains a web portal dedicated to higher education in Türkiye. Detailed datasets about universities, faculties, and departments can be obtained from the portal. Using the data provided by the portal, detailed analysis can be done such as the understanding impact of higher education on activities in the economy connected to movements of the students within or between cities. Especially such activity can be observed in real estate since students rent flats or rooms. Moreover, this data helps researchers analyze changes in students’ preferences in terms of higher education over time. Although this site contains a variety of important information, it does not provide any Application Programming Interfaces (API) or any other possibilities to easily download or query the data in one place. This paper introduces thestats, a user-friendly R data package designed to make higher education statistics easily accessible. Researchers can use the package to query data, which is already scraped from the portal, using the R functions provided by the package. Thanks to the package, researchers do not need to perform any further effort to delve into Turkish higher education statistics. It is sufficient for the researchers to use the package to begin exploring.
Three-dimensional numerical investigation of hybrid nanofluids in chain microchannel under electrohydrodynamic actuator
- Milad Amiri
- Dariusz Mikielewicz
2023 Pełny tekst NUMERICAL HEAT TRANSFER PART A-APPLICATIONS
Energy efficiency enhancement methods have received considerable attentionwithin the industry and scientific community, owing to the rising concern ofglobal energy sustainability. The present article attempts to scrutinize the effectsof electrohydrodynamics and nanofluids on the rate of heat transfer and fluidflow in the 3-D chain microchannels. Improved heat exchangers (e.g., chainmicrochannel) would have a key role in increasing of the performance of suchsystems since they provide efficient thermal management needed for morerobust computational power. To date, analysis of electrohydrodynamics andnanofluids in the chain microchannel was not comprehensively discussed. Here,steady-state, laminar, and three-dimensional chain microchannel are numeric-ally modeled based on a control volume method in Fluent. Results show thatby increasing the volume fraction of nanoparticles, the viscosity of the nanofluidincreases leading to an increase in pressure drops. Moreover, Nusselt at Re¼125, 250, 500 and 1000 for hybrid nanofluid (; AL2O3¼; CuO¼4%) is 1.206,1.541, 2.075 and 2.707, respectively which, in turn, depicts surging by 22.94%,24.17%, 24.70% and 24.707% in comparison to water, respectively. In addition,at low Reynolds number (0.416Re4:166Þ, the lower Reynolds results indecreasing of percentage of pressure drop. Meanwhile, imposing electrohydro-dynamic (V¼30 KV) at Re¼125, 250, 500 and 1000 leads to increasing by 23%,22%, 20% and 18% of Nusselt number in comparison to absence of electricfield, respectively. It means that the considered effect of the increasing theNusselt number at lower Reynolds number is more effective. Moreover, heattransfer rises with augmentation of supplied voltage and Reynolds number.
ThreSpect – A Program for the Determination of the Appearance Energies of Neutral and Ionized Species
- Michał Jurkowski
- Damian Głowienka
- Tomasz Wąsowicz
2023 Romanian Journal of Physics
Collisions of photons and charged particles with molecules lead to their excitation, ionization, and dissociation into neutral and ionized fragments. Accurately determining thresholds of the formation of particular products plays a vital role in analyzing processes occurring during these interactions. Therefore, we present a computer program, “ThreSpect,” that allows calculating threshold energies of various species generated in these collisions irrespective of whether they are recorded with mass spectrometric or emission spectroscopic techniques.
Throughput Accounting – Rachunkowość Zarządcza w rękach managerów
- Jerzy Kuncicki
- Joanna Czerska
2023
Literatury na temat rachunkowości zarządczej i rachunku kosztów jest tak dużo, że każdy zainteresowany łatwo znajdzie coś dla siebie w dobrych księgarniach. Nie będziemy cytowali definicji, kategorii czy rozwiązań w rachunku kosztu ani nie dajemy czytelnikom podręcznika z zakresu stosowania rachunku kosztów. Chcemy natomiast podzielić się naszym – dyrektora finansowego oraz dyrektora produkcji – doświadczeniem, odkryciami, a także pasją, jaką jest rachunek kosztów i którą od wielu lat stosujemy w życiu zawodowym. W dość długiej już drodze zawodowej mieliśmy przyjemność poznania wielu firm o różnym profilu działalności, z różnych branż i o różnej wielkości. W każdej z nich Jerzy Kuncicki zajmował się bezpośrednio bądź pośrednio rachunkiem kosztów, a Joanna Czerska ponosiła skutki tego rachunku, realizując projekty doskonalące, nakierowane na poprawę wyników firmy i redukcję kosztów. Mieliśmy przyjemność pracować na wysokich stanowiskach, co umożliwiło nam szersze spojrzenie na systemy informacyjne, w tym na rachunek kosztów w powiązaniu ze strategią firmy. Oboje mieliśmy możliwość dogłębnego poznania produkcji w różnych branżach i związanych z tą produkcją systemów rachunku kosztów. A teraz chcemy podzielić się z czytelnikami tym doświadczeniem i wynikającymi z niego spostrzeżeniami. Książkę zbudowaliśmy tak, jak wyglądała nasza droga do znalezienia odpowiedzi na nurtujące nas pytania. Zaczynamy zatem od ustalenia, do czego potrzebny jest nam, managerom, rachunek kosztów i jakie błędy popełnialiśmy, stosując tradycyjny rachunek kosztów. W kolejnym rozdziale skupiamy się na zidentyfikowaniu przyczyny tych błędów. Dalej przedstawiamy Throughput Accounting, który pomógł rozwiązać nasze problemy. Najwięcej miejsca poświęciliśmy na pokazanie czytelnikom możliwości użycia Throughput Accounting do podejmowania decyzji managerskich. Decyzji, z którymi mierzyliśmy się w zawodowej pracy, a które z pewnością są wyzwaniem i dla czytelników. Ponieważ decyzje managerów zależą od sytuacji rynkowej firmy, podzieliliśmy przykłady na dwie grupy. Pierwsza grupa – to scenariusze dla firm, które wykorzystały moce wytwórcze, ograniczające możliwości dowolnego kształtowania sprzedaży. Druga grupa – to scenariusze dla przedsiębiorstw mierzących się z ograniczeniem rynkowym, czyli posiadających niewykorzystane moce wytwórcze. Zapraszamy do lektury! Joanna Czerska, Jerzy Kuncicki
Ti-Fe2O3/In2O3 as photoactive material: The role of the substrate in photoelectrochemical water oxidation
- Mariusz Szkoda
- Anna Ilnicka
- Zuzanna Zarach
- Daria Roda
- Andrzej Nowak
- Konrad Trzciński
2023 JOURNAL OF ALLOYS AND COMPOUNDS
The layers of Ti-Fe2O3/In2O3 were prepared on the different substrates using hydrothermal method: Ti/TiO2 nanotubes, Ti foil, FTO and FTO/TiO2. Materials were characterized using scanning electron microscopy, XRD, Raman, UV-Vis, and X-ray photoelectron spectroscopy and tested as photoanodes for water oxidation under illumination. The formation of heterojunction on the TiO2 nanotubes increases photocurrent of water oxidation at 0.7 V vs. RHE to over 520 μA/cm2, while Ti/Ti-Fe2O3/In2O3, FTO/Ti-Fe2O3/In2O3, and FTO/TiO2/Ti-Fe2O3/In2O3 exhibit 130, 31 and 152 μA/cm2, respectively. Thus, the work indicates that the presence of TiO2 in the form of nanotubes as a substrate increases the efficiency of photocurrent generation.
Time fractional analysis of Casson fluid with application of novel hybrid fractional derivative operator
- Aziz Ur Rehman
- Muhammad Riaz
- Ilyas Khan
- Abdullah Mohamed
2023 Pełny tekst AIMS Mathematics
A new approach is used to investigate the analytical solutions of the mathematical fractional Casson fluid model that is described by the Constant Proportional Caputo fractional operator having non-local and singular kernel near an infinitely vertical plate. The phenomenon has been expressed in terms of partial differential equations, and the governing equations were then transformed in non-dimensional form. For the sake of generalized memory effects, a new mathematical fractional model is formulated based on the newly introduced Constant Proportional Caputo fractional derivative operator. This fractional model has been solved analytically, and exact solutions for dimensionless velocity, concentration and energy equations are calculated in terms of Mittag-Leffler functions by employing the Laplace transformation method. For the physical significance of various system parameters such as α , β , Pr , Gr , Gm , Sc on velocity, temperature and concentration profiles, different graphs are demonstrated by Mathcad software. The Constant Proportional Caputo fractional parameter exhibited a retardation effect on momentum and energy profile, but it is visualized that for small values of Casson fluid parameter, the velocity profile is higher. Furthermore, to validated the acquired solutions, some limiting models such as the ordinary Newtonian model are recovered from the fractionalized model. Moreover, the graphical representations of the analytical solutions illustrated the main results of the present work. Also, from the literature, it is observed that to deriving analytical results from fractional fluid models developed by the various fractional operators is difficult, and this article contributes to answering the open problem of obtaining analytical solutions for the fractionalized fluid models.
Time series analysis and impact assessment of the temperature changes on the vegetation and the water availability: A case study of Bakun-Murum Catchment Region in Malaysia
- Vipin Kumar Oad
- Adam Szymkiewicz
- Nabeel Ali Khan
- Shahzad Ashraf
- Rab Nawaz
- Abdelrazek Elnashar
- Syed Saad
- Abdul Hannan Qureshi
2023 Remote Sensing Applications: Society and Environment
The Bakun-Murum (BM) catchment region of the Rajang River Basin (RRB), Sarawak, Malaysia, has been under severe threat for the last few years due to urbanization, global warming, and climate change. The present study aimed to evaluate the time series analysis and impact assessment of the temperature changes on the vegetation/agricultural lands and the water availability within the BM region. For this purpose, the Landsat data for the past thirty years (1990–2020) were used. Remote sensing techniques for estimating the surface temperatures and variation within the vegetation and water bodies were utilized, and validation was done using on-ground weather stations. Google Earth Engine (GEE) and other RS & GIS tools were used for analyzing the time series trends of land surface temperature (LST), normalized difference vegetation index (NDVI), and normalized difference water index (NDWI). The results exposed an overall rise of 1.06 °C in the annual mean temperatures over the last thirty years. A maximum annual mean NDVI of 0.48 was recorded for 2018 and 2019. The lowest annual mean NDVI (0.27) was observed in 2005. The annual mean NDWI increased to 0.48 in 2018 and 2019, respectively. The statistical correlation results revealed the coefficient of determination (R2) of 0.09 and 0.13 for the annual mean LST and annual mean NDVI and the annual mean LST and annual mean NDWI, respectively. Moreover, the Mann-Kendall trend test for the annual mean temperature series indicates a slightly increasing trend with Sen's slope of 0.03 °C/year. It is found that there is a positive trend in the annual mean rainfall patterns, as Sen's slope indicates a yearly increase of 50.58 mm/year. This study found significant changes in the LST, NDVI, and NDWI of the BM catchment region during the last thirty years, demanding the concerned authorities' instant attention to alleviate the adverse effects of such changes to protect the ecosystem.
TIME-DOMAIN NUMERICAL EVALUATION OF SHIP RESISTANCE AND MOTION IN REGULAR WAVES BY USING THE CFD URANS METHOD
- Mohamad Sadeghi
- Hamid Zeraatgar
- Mohammad Ghaemi
- Mojtaba Barjasteh
2023 Pełny tekst
Taking into account the International Maritime Organisation’s (IMO) strategy to radically reduce the GHG emitted by the shipping industry towards zero emission operation, today's assessment of ship behaviour in waves, its seakeeping characteristics and resistance and their interrelation with fuel consumption and emissions are one of the most attended research subject. There are three methods to conduct this analysis, which are Experimental Fluid Dynamics (FED), numerical methods e.g. Computational Fluid Dynamics (CFD) and empirical analysis. This study shows the results of time-domain analysis of ship motions and resistance in head sea waves by using the CFD method, which is then verified using the experimental results. The tests were run for different wavelengths for a KCS model. Numerical results, which are based on solving Unsteady Reynolds Averaged Navier-Stokes equations (URANS) show that the CFD method applied by using STAR CCM+ can be reliable for evaluating the ship seakeeping characteristics and resistance in waves.
Time-Gating method with automatic calibration for accurate measurements of electrically small antenna radiation patterns in Non-Anechoic environments
- Adrian Bekasiewicz
- Sławomir Kozieł
- Michał Czyż
2023 Pełny tekst MEASUREMENT
Non-anechoic sites represent a cheap alternative to measurements of antennas in dedicated facilities. However, due to a high noise—from the external EM signal sources and multipath interferences—the quality of radiation patterns obtained in non-anechoic conditions is poor. The characteristics can be corrected using a time-gating method (TGM), which involves filtering of the noise based on temporal analysis of the measured signals. Unfortunately, determination of appropriate TGM setup is prone to failure due to its manual, or semi-manual nature. In this work, an automatic TGM calibration algorithm for accurate measurements in non-anechoic environments has been proposed. The method involves calibration of the test site using the antenna with known accurate responses. The process is implemented as an optimization routine where TGM intervals are adjusted through a curve fitting of the on-site measurements to the reference radiation patterns. The proposed framework has been demonstrated using four compact radiators and validated against the state-of-the-art techniques. Applicability of the method for calibration of the measurements in distinct test sites, as well as the analysis of the aliasing and external noise on the quality of corrected measurements have also been investigated.
TIME-OF-FLIGHT DIFFERENTIAL ELECTRON SCATTERING FROM MOLECULAR TARGETS: BENCHMARK CROSS SECTIONS
- Mateusz Zawadzki
- Murtadha Khakoo
2023
We report time-of-flight differential cross section (DCS) measurements for the electron impact excitation transition in H2. In this work, agreement between available theory and experiment is excellent overall, and marks a transition in electron molecule scattering where differential scattering of excitation is found to be in such precise agreement. We also prove that the newly built apparatus can be used for accurate measurement of the mass stopping power for low energy electrons for H2 for which agreement between theory and experiment is found to be excellent.
TiO2-C nanocomposite synthesized via facile surfactant-assisted method as a part of less energy-consuming LED-based photocatalytic system for environmental applications
- Adam Kubiak
- Anna Grzegórska
- Elżbieta Gabała
- Joanna Zembrzuska
- Mirosław Szybowicz
- Hubert Fuks
- Anna Szymczyk
- Anna Zielińska-Jurek
- Marek Sikorski
- Teofil Jesionowski
2023 JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
A novel facile method was used to incorporate carbon into the titania structure. An alternative synthesis method of carbon-doped TiO2 has been proposed by using a widely used and cheap surfactant. During the process, cetyltrimethylammonium bromide plays a dual role, as a morphology modifier and as a carbon source. The presented approach allows obtained TiO2-C nanostructures to be anatase nanocrystals with carbon being deposited either on the surface or between the TiO2 nanoparticles. The innovative nature of the research subject is related to the design of cheap LED solutions and facile synthesis of TiO2-C for use in novel energy-saving photocatalytic systems. Photocatalytic studies showed promising activity in the oxidation of 4-chlorophenol. Furthermore, it was indicated that LED-based photocatalytic systems allow a significant reduction in energy consumption compared to conventional photocatalytic sets. In addition, the high thermal efficiency of LED systems was confirmed with a thermal imaging camera. Hence, the presented novel LED photocatalytic systems can be an important part of a broad strategy for the protection of the environment.