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Debonding of coin-shaped osseointegrated implants: Coupling of experimental and numerical approaches
- Yoann Hériveaux
- Sophie Le Cann
- Katharina Immel
- Elsa Vennat
- Vu-Hieu Nguyen
- Vladimir Brailovski
- Patrick Karasinski
- Roger Sauer
- Guillaume Haiat
2023 Journal of the Mechanical Behavior of Biomedical Materials
While cementless implants are now widely used clinically, implant debonding still occur and is difficult to anticipate. Assessing the biomechanical strength of the bone–implant interface can help improving the understanding of osseointegration phenomena and thus preventing surgical failures. A dedicated and standardized implant model was considered. The samples were tested using a mode III cleavage device to assess the mechanical strength of the bone-implant interface by combining experimental and numerical approaches. Four rough (Sa = 24.5 μm) osseointegrated coin-shaped implants were left in sheep cortical bone during 15 weeks of healing time. Each sample was experimentally rotated at 0.03◦/sec until complete rupture of the interface. The maximum values of the torque were comprised between 0.48 and 0.72 Nm, while a significant increase of the normal force from 7-12 N to 31–43 N was observed during the bone-implant interface debonding, suggesting the generation of bone debris at the bone-implant interface. The experimental results were compared to an isogeometric finite element model describing the adhesion and debonding phenomena through a modified Coulomb’s law, based on a varying friction coefficient to represent the transition from an unbroken to a broken bone-implant interface. A good agreement was found between numerical and experimental torques, with numerical friction coefficients decreasing from 8.93 to 1.23 during the bone-implant interface rupture, which constitutes a validation of this model to simulate the debonding of an osseointegrated bone-implant interface subjected to torsion.
Decomposition of the induced magnetism degaussing problem for fast determination of currents in demagnetization coils wrapped outside an object under arbitrary external field conditions
- Mirosław Wołoszyn
- Jarosław Tarnawski
- Joanna Wołoszyn
2023 Pełny tekst JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
Safe passage of ships in the presence of sea mines can be ensured by limiting or reducing the ship’s magnetic footprint. For vessels with plastic hulls, the main component that requires magnetic damping is the engine. Demagnetization of such an object can be achieved by wrapping it with coils and setting the direct current appropriately. For each specific geographic location, the currents in the coils can be determined iteratively from measurements of the magnetic signature in the cardinal directions. In this paper the magnetic signatures are calculated using decomposition-based approach for each coil and each component of the external field separately. Hence the overall magnetic signature of the object can be reproduced in arbitrary external magnetic field (i.e. anywhere on the Earth). Knowing the influence of each coil, it is possible to formulate the optimization task (signature minimization) and determine the currents. The presented method is verified in FEM software with the use of engine models of both symmetrical and asymmetrical shapes. Since the determination of the currents takes place as a result of solving the optimization problem, the effectiveness of obtaining the results, the speed of convergence and the dependence on initial conditions is under investigation. The effect of the model mesh size on the quality of object signature reduction is also analyzed. The developed method can be used for a real object. In that case acquiring the data then requires the measurements of the object placed inside the Helmholtz coils.
Deep eutectic solvents – Ideal solution for clean air or hidden danger?
- Farooque Janjhi
- Roberto Castro Munoz
- Grzegorz Boczkaj
2023 SEPARATION AND PURIFICATION TECHNOLOGY
The industrial sector is one of the fastest-growing sources of greenhouse gases, due to its excessive energy consumption to meet the rapidly growing demand for energy-intensive products. The use of deep eutectic solvents (DESs) has been studied extensively in order to cope with these harmful gases, but their usage can be an issue in respect to ecological reasons. Do deep eutectic solvents harm the atmosphere? Yes, these solvents can be harmful if their constituents (HBA and HBD) that are volatile and toxic in nature. A number of scientific reports preset their application without care on cross-contamination of treated media. Herein, we highlight the ecotoxicity behavior of DESs as treatment materials for three major toxic gas treatment methods, including carbon dioxide (CO2) capture, biogas treatment and air purification. Special attention is given to the health consequences of HBDs due to their toxicity and emission outside of the treatment system into the environment. The physicochemical characteristics of DESs are evaluated and addressed in comparison to the benchmark solvents. Emission of DESs can be predicted based on simulation software like COSMO-RS or Molecular Dynamics (MD). Furthermore, we suggest some simple protocols to estimate this issue and thus make aware researchers to think about it when experimenting with DES for different applications.
Deep eutectic solvents in analytical sample preconcentration Part B: Solid-phase (micro)extraction
- Justyna Werner
- Agnieszka Zgoła-Grześkowiak
- Julia Płatkiewicz
- Justyna Płotka-Wasylka
- Natalia Jatkowska
- Alina Kalyniukova
- Serhii Zaruba
- Vasil Andruch
2023 MICROCHEMICAL JOURNAL
One of the key challenges of modern analytical chemistry is the monitoring of trace amounts of contaminants using sensitive and selective instrumental techniques. Due to the variety and complexity of some samples, it is often necessary to properly prepare a sample and to perform a preconcentration of trace amounts of analytes. In line with the principles of Green Analytical Chemistry (GAC), it is important for an analytical procedure to reduce labor and time consumption and to decrease the use of volatile and hazardous solvents. Therefore, solvent-free extraction techniques, such as SPE, μSPE, SPME and their various modifications, which are mainly aimed at increasing their “greenness”, have been very popular for many years. Deep eutectic solvents fit perfectly into GAC principles, which is why they have been used as extractants in liquid-phase microextraction techniques for a long time. This review is a follow-up to our recently published article on the use of deep eutectic solvents (DESs) in liquid-phase microextraction techniques and summarizes the most important applications of DES in solid-phase (micro)extraction techniques.
Deep Eutectic Solvents: Properties and Applications in CO2 Separation
- Iwona Cichowska-Kopczyńska
- Bartosz Nowosielski
- Dorota Warmińska
2023 Pełny tekst MOLECULES
Nowadays, many researchers are focused on finding a solution to the problem of global warming. Carbon dioxide is considered to be responsible for the “greenhouse” effect. The largest global emission of industrial CO2 comes from fossil fuel combustion, which makes power plants the perfect point source targets for immediate CO2 emission reductions. A state-of-the-art method for capturing carbon dioxide is chemical absorption using an aqueous solution of alkanolamines, most frequently a 30% wt. solution of monoethanolamine (MEA). Unfortunately, the usage of alkanolamines has a number of drawbacks, such as the corrosive nature of the reaction environment, the loss of the solvent due to its volatility, and a high energy demand at the regeneration step. These problems have driven the search for alternatives to that method, and deep eutectic solvents (DESs) might be a very good substitute. Many types of DESs have thus far been investigated for efficient CO2 capture, and various hydrogen bond donors and acceptors have been used. Deep eutectic solvents that are capable of absorbing carbon dioxide physically and chemically have been reported. Strategies for further CO2 absorption improvement, such as the addition of water, other co-solvents, or metal salts, have been proposed. Within this review, the physical properties of DESs are presented, and their effects on CO2 absorption capacity are discussed in conjunction with the types of HBAs and HBDs and their molar ratios. The practical issues of using DESs for CO2 separation are also described.
Deep-Learning-Based Precise Characterization of Microwave Transistors Using Fully-Automated Regression Surrogates
- Nurullah Calik
- Filiz Gunes
- Sławomir Kozieł
- Anna Pietrenko-Dąbrowska
- Mehmet Belen
- Peyman Mahouti
2023 Pełny tekst Scientific Reports
Accurate models of scattering and noise parameters of transistors are instrumental in facilitating design procedures of microwave devices such as low-noise amplifiers. Yet, data-driven modeling of transistors is a challenging endeavor due to complex relationships between transistor characteristics and its designable parameters, biasing conditions, and frequency. Artificial neural network (ANN)-based methods, including deep learning (DL), have been found suitable for this task by capitalizing on their flexibility and generality. Yet, rendering reliable transistor surrogates is hindered by a number of issues such as the need for finding good match between the input data and the network architecture and hyperparameters (number and sizes of layers, activation functions, data pre-processing methods), possible overtraining, etc. This work proposes a novel methodology, referred to as Fully Adaptive Regression Model (FARM), where all network components and processing functions are automatically determined through Tree Parzen Estimator. Our technique is comprehensively validated using three examples of microwave transistors and demonstrated to offer a competitive edge over the state-of-the-art methods in terms of modeling accuracy and handling the aforementioned issues pertinent to standard ANN-based surrogates.
Deformation of an elastic second gradient spherical body under equatorial line density of dead forces
- Isola dell'Isola
- Victor Eremeev
- V Korolenko
- Yuri Solyaev
2023 EUROPEAN JOURNAL OF MECHANICS A-SOLIDS
We consider deformations of an elastic body having initially a spherical shape. Assumed deformation energy depends on the first and second gradient of displacements. We apply an equatorial line density of dead loads, that are forces per unit line length directed in radial direction and applied along the equator of the sphere. We restrict ourselves our analysis to the case of linearized second strain gradient isotropic elasticity (for which the more general energy was determined by Mindlin) with only one characteristic length. Differently to what happens in first gradient continua, i.e. in classic linear elasticity, we show that for the particular class second gradient continua considered here these forces do not determine infinite displacements in the direction of applied dead line forces. Instead, using a series method for the solution of the considered boundary-value problem, we demonstrate that the displacements are finite. So in the deformed configuration there is not the formation of an edge at the material points where the forces are applied. Further investigations are therefore needed for establishing if this elastic-regime edge formation is made possible: (I) either in the case of more general linear elastic constitutive equations or (II) only when large deformations are considered or (III) if non-elastic phenomena are involved.
Degradation of bisphenol S – a contaminant of emerging concern - by synergistic ozone and percarbonate based AOP
- Zahra Askarniya
- Manoj P Rayaroth
- Xun Sun
- Zhaohui Wang
- Grzegorz Boczkaj
2023 Pełny tekst Water Resources and Industry
Degradation of bisphenol S was studied using ozone activated by sodium percarbonate and the effectiveness of optimized process was compared with the peroxone process. The influence of several factors including sodium percarbonate concentration, ozone dose, pH, and water matrix were investigated. A synergetic coefficient of 3.84 was achieved for the combination of sodium percarbonate and ozone, confirming the effectiveness of this hybrid process. Scavenging tests revealed, that carbonate radicals, hydroxyl radicals, superoxide radicals, and singlet oxygen contributed to the degradation of bisphenol S. At the same operating condition, degradation effectiveness values of 99% and 81% were obtained by ozone combined with sodium percarbonate and hydrogen peroxide, respectively, demonstrating the superiority of sodium percarbonate over hydrogen peroxide in combination with ozone for the degradation of bisphenol S. Low concentration of inorganic anions had a negligible effect on the degradation, while carbonate ions increased the first-order degradation rate constant by 56%.
Degradation of cefadroxil drug by newly designed solar light responsive alcoholic template-based lanthanum ferrite nanoparticles
- Ammara Nazir
- Muhammad Imran
- Farah Kanwal
- Shoomaila Latif
- Ayesha Javaid
- Tak H. Kim
- Grzegorz Boczkaj
- Ashwag Shami
- Hafiz M.N. Iqbal
2023 ENVIRONMENTAL RESEARCH
In this work, lanthanum ferrite nanoparticles were synthesized via a simple co-precipitation method. Two different templates, namely sorbitol and mannitol, were used in this synthesis to tune the optical, structural, morphological, and photocatalytic properties of lanthanum ferrite. The synthesized lanthanum ferrite-sorbitol (LFOCo-So) and lanthanum ferrite-mannitol (LFOCo-Mo) were investigated through Ultraviolet–Visible (UV–Vis), X-ray diffraction (XRD), Fourier Transform Infra-Red (FTIR), Raman, Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX), and photoluminescence (PL) techniques to study the effects of the templates on the tunable properties of lanthanum ferrite nanoparticles. The UV–Vis study revealed a remarkably small bandgap (2.09 eV) of LFOCo-So compared to the LFOCo-Mo having a band gap of 2.46 eV. XRD analysis revealed a single-phased structure of LFOCo-So, whereas LFOCo-Mo showed different phases. The calculated crystallite sizes of LFOCo-So and LFOCo-Mo were 22 nm and 39 nm, respectively. FTIR spectroscopy indicated the characteristics of metal-oxygen vibrations of perovskites in both lanthanum ferrite (LFO) nanoparticles, whereas a slight shifting of Raman scattering modes in LFOCo-Mo in contrast to LFOCo-So showed the octahedral distortion of the perovskite by changing the template. SEM micrographs indicated porous particles of lanthanum ferrite with LFOCo-So being more uniformly distributed, and EDX confirmed the stoichiometric ratios of the lanthanum, iron, and oxygen in the fabricated lanthanum ferrite. The high-intensity green emission in the photoluminescence spectrum of LFOCo-So indicated more prominent oxygen vacancies than LFOCo-Mo. The photocatalytic efficiency of synthesized LFOCo-So and LFOCo-Mo was investigated against cefadroxil drug under solar light irradiation. At optimized photocatalytic conditions, LFOCo-So showed higher degradation efficiency of 87% in only 20 min than LFOCo-Mo having photocatalytic activity of 81%. The excellent recyclability of the LFOCo-So reflected that it could be reused without affecting photocatalytic efficiency. These findings showed that sorbitol is a useful template for the lanthanum ferrite particles imparting outstanding features, enabling it to be used as an efficient photocatalyst for environmental remediation.
Degradation of Rhodamine dyes by Advanced Oxidation Processes (AOPs) – Focus on cavitation and photocatalysis - A critical review
- Ashish V. Mohod
- Malwina Momotko
- Noor S. Shah
- Mateusz Marchel
- Mohammad Imran
- Lingshuai Kong
- Grzegorz Boczkaj
2023 Pełny tekst Water Resources and Industry
This review evaluates selected advanced oxidation processes (AOPs) - cavitation and photocatalysis - successfully used for wastewater treatment towards degradation of Rhodamine (Rh) dyes. Reactor configuration and impact of process parameters and oxidants addition (hydrogen peroxide, ozone, persulfates) on degradation effectiveness along with degradation mechanisms are discussed. Best technologies provide 100% degradation within 10–30 min. Rhodamine B is effectively degraded in highly acidic conditions (pH 2), while Rhodamine 6G requires basic conditions (pH 10). The most effective oxidants were hydrogen peroxide and ozone. Ecological Structure Activity Relationships (ECOSAR) revealed acute toxicities of the intermediates and by-products of the Rh dye.
Dehydrogenation in electron-induced dissociative ionization of pyridine molecule
- Michał Jurkowski
- Tomasz Wąsowicz
2023 Romanian Journal of Physics
The electron-impact dissociative ionization of pyridine has been investigated using mass spectrometry. Thirty-two well-resolved mass peaks have been identified in the cation mass spectra and assigned to the most likely ionic molecular fragments. The new sixteen ionic fragments' appearance energies have been determined, and sixteen others remeasured. The total cross-section for electron-impact ionization of pyridine has been measured at 100 eV. Thorough analysis indicates that at least three peaks' groups in the mass spectra occur via the shake-off dehydrogenation mechanism, i.e., by sequential hydrogen atoms elimination from the pyridine parent cation or its fragmentation products. The nature of this process is deciphered.
Dekodowanie kodów iterowanych z użyciem sieci neuronowej
- Oskar Fiedot
- Marek Blok
2023 Pełny tekst Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne
Nadmiarowe kody iterowane są jedną z prostych metod pozyskiwania długich kodów korekcyjnych zapewniających dużą ochronę przed błędami. Jednocześnie, chociaż ich podstawowy iteracyjny dekoder jest prosty koncepcyjnie oraz łatwy w implementacji, to nie jest on rozwiązaniem optymalnym. Poszukując alternatywnych rozwiązań zaproponowano, przedstawioną w pracy, strukturę dekodera tego typu kodów wspomaganą przez sieci neuronowe. Zaproponowane rozwiązanie pozwala na wykrywanie oraz korekcję błędów w odbieranych ciągach.
DEM Analyses of Interface Behaviour Between Cohesionless Sand and Rigid Wall of Different Roughness
- Aleksander Grabowski
- Michał Nitka
- Andrzej Tejchman-Konarzewski
2023
Artykuł dotyczy trójwymiarowych symulacji numerycznych quasi-statycznego ścinania między niespoistym piaskiem a sztywnymi ścianami w aparacie bezpośredniego ścinania ścian. Chropowatość ścian sztywnych wahała się od gładkiej do bardzo szorstkiej. Na górną ścianę działało stałe ciśnienie normalne. Symulacje numeryczne przeprowadzono metodą elementów dyskretnych (DEM). Ziarna piasku opisywano jako kulki z momentami kontaktowymi lub jako niesymetryczne nieregularne grudki. Zbadano wpływ chropowatości powierzchni na makroskopowe krzywe siła-przemieszczenie oraz na wyniki mikroskopowe na poziomie ziarna. Dla różnych chropowatości ścian obliczono wysokość strefy zlokalizowanej ścinania, rotacje ziaren oraz stosunek między poślizgami i rotacjami ziaren. Zaproponowano dwa różne warunki brzegowe wzdłuż ściany dla kontinuów mikropolarnych, biorąc pod uwagę rotacje i poślizgi ziaren oraz znormalizowaną chropowatość granicy faz. Wyniki DEM pozwalają lepiej zrozumieć zachowanie interfejsu między ciałami ziarnistymi a sztywnymi strukturami.
Dependent self-employed individuals: are they different from paid employees?
- Ondřej Dvouletý
- Dagmara Nikulin
2023 Pełny tekst Employee Relations
This study focuses on dependent self-employment, which covers a situation where a person works for the same employer as a typical worker while on a self-employment contractual basis, i.e., without a traditional employment contract and without certain rights granted to "regular" employees. The research exploits the individual-level dataset of 35 European countries extracted from the 2017 edition of the European Labour Force Survey and compares the characteristics of employees and dependent self-employed individuals. Methodologically, the study relies on the estimation of a multivariate logistic regression model. The main hypothesis assuming that dependent self-employed work most often in low-skilled occupations was empirically supported. There was also a non-linear (u-shaped) relationship between the years of accumulated experience (with a turning point at 35 years) and the likelihood of being dependent self-employed. Other results showed that dependent self-employed are less likely to be women, and they are more likely born outside of the countries where they participate in the labour markets. The study contributes to the field by adopting a comparable definition of dependent self-employment and exploiting the recent theoretical support of The Work Precarity Framework. The phenomenon should still be addressed by policymakers and labour office representatives, aiming to protect, primarily, vulnerable lower-skilled workers. The ongoing research should study the longitudinal dimension of dependent self-employment with a focus on motivational aspects.
Depolarisation Model for a BAN Indoor Scenario
- Manuel M. Ferreira
- Filipe D. Cardoso
- Sławomir Ambroziak
- Mariella Särestöniemi
- Kenan Turbic
- Luis M. Correia
2023 Pełny tekst
In this paper, an analysis of depolarisation in Body Area Networks for Body-to-Infrastructure communications based on a measurement campaign in the 5.8 GHz band in an indoor environment is performed. Measurements were made with an offbody antenna transmitting linearly polarised signals and dualpolarised receiving antennas carried by the user on the body. A Normal Distribution with a mean of 2.0 dB and a standard deviation of 4.3 dB is found to be the best fit for modelling crosspolarisation discrimination. The average correlation between the signals received by the orthogonally polarised antennas is below 0.5, showing that polarisation diversity can be used. A model is proposed for the average value of the standard deviation of the cross-polarisation discrimination ratio as a function of the transmitted polarisation, the mobility of users and link dynamics.
Der Begriff des Mythos bei Cassirer: zwischen UIdealismus, Ethnologie, politischer Philosophie und allgemeine Kulturphilosophie
- Andrzej Karalus
2023
Der Mythos war eines der bevorzugten Forschungsobjekte Cassirers, denen er zwei Bücher, zahlreiche Artikel und wichtige längere Aufsätze widmete. In diesem Artikel versuche ich Cassirers Mythendeutung kurz zu rekapitulieren, um ihre Position in der Gesamtheit seines philosophischen Systems festzulegen und ihr Erklärungspotenzial zu gewinnen. In erstem Teil handle ich das allgemeine Problem des mythischen Denkens hauptsächlich aufgrund des zweiten Teils der Philosophie der symbolischen Formen ab. Ich möchte hierbei aufzeigen, dass der Mythos als symbolische Form einen Versuch der Vereinheitlichung der theoretischen Impulse des Deutschen Idealismus mit Feststellungen empirisch orientierter Kulturwissenschaften repräsentiert. Im zweiten Teil bespreche ich das Problem des Mythos aus Sicht der politischen Philosophie und im Hinblick auf die Totalitarismus-Debatte. In drittem Teil bespreche ich schließlich die Vorteile und Beschränkungen der Konzeption des totalitären Staates Cassirers und versuche seine Mythenauffassung in seine allgemeine Kulturphilosophie einzupflegen. Ich schlage vor, dass der Schlüssel zur fruchtbarsten Behandlung dieser Thematik vorerst in Das mythischen Denken zu finden ist, nicht in The Myth of the State. Ich weise auch auf die potentiellen Anwendungsbereiche seiner Betrachtungen hin.
Design advantages and analysis of a novel five-phase doubly-fed induction generator
- Roland Ryndzionek
- Michał Michna
- Filip Kutt
- Grzegorz Kostro
- Krzysztof Blecharz
2023 Pełny tekst COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING
Purpose – The purpose of this paper is to provide an analysis of the performance of a new five-phase doubly fed induction generator (DFIG). Design/methodology/approach – This paper presents the results of a research work related to fivephase DFIG framing, including the development of an analytical model, FEM analysis as well as the results of laboratory tests of the prototype. The proposed behavioral level analytical model is based on the winding function approach. The developed DFIG model was used at the design stage to simulate the generator’s no-load and load state. Then, the results of the FEM analysis were shown and compared with the results of laboratory tests of selected DFIG operating states. Findings – The paper provides the results of analytical and FEM simulation and measurement tests of the new five-phase dual-feed induction generator. The use of the MATLAB Simscape modeling language allows for easy and quick implementation of the model. Design assumptions and analytical model-based analysis have been verified using FEM analysis and measurements performed on the prototype. The results of the presented research validate the design process as well as show the fivephase winding design advantage over the three-phase solution regarding the control winding power quality. Research limitations/implications – The main disadvantage of the winding function approach-based model development is the simplification regarding omitting the tangential airgap flux density component. However, this fault only applies to large airgap machines and is insignificant in induction machines. The results of the DFIG analyses were limited to the basic operating states of the generator, i.e. the no-load state, the inductive and resistive load. Practical implications – The novel DFIG with five phase rotor control winding can operate as a regular three-phase machine in an electric power generation system and allows for improved control winding power quality of the proposed electrical energy generation system. This increase in power quality is due to the rotor control windings inverter-based PWM supply voltage, which operates with a wider per-phase supply voltage range than a three-phase system. This phenomenon was quantified using control winding current harmonic analysis.
Design and Evaluation of the Compact and Autonomous Energy Subsystem of a Wave Energy Converter
- Marcin Drzewiecki
- Jarosław Guziński
2023 Pełny tekst ENERGIES
This paper presents the results of the design process focused on the development of the energy subsystem (ES) of a wave energy converter (WEC). The ES is an important electrical part that significantly affects the energy reliability and energy efficiency of the entire WEC device. The designed ES was intended for compact WECs powering IoT network devices working in the distributed grid. The developed ES is an electronic circuit consisting of three cooperating subsystems used for energy conversion, energy storage, and energy management. The energy conversion subsystem was implemented as a set of single-phase bridge rectifiers. The energy storage subsystem was a battery-less implementation based on the capacitors. The energy management subsystem was implemented as a supervisory circuit and boost converter assembly. The designed ES was verified using the physical experiment method. The model experiment reflected the operation of the designed ES with a piezoelectric PZT-based WEC. The experimental results showed a 41.5% surplus of the energy supplied by ES over the energy demanded by the considered load at a duty cycle of ca. 6 min—37.2 mJ over 26.3 mJ, respectively. The obtained results have been evaluated and discussed. The results confirmed the designed ES as a convenient solution, which makes a significant contribution to the compact WECs that can be applied among others to a distributed grid of autonomous IoT network devices powered by free and renewable energy of sea waves. Finally, it will also enable sustainable development of mobile and wireless communication in those maritime areas where other forms of renewable energy may not be available.
Design and Optimization of a Compact Super-Wideband MIMO Antenna with High Isolation and Gain for 5G Applications
- Bashar Esmail
- Sławomir Kozieł
- Anna Pietrenko-Dąbrowska
2023 Pełny tekst Electronics
This paper presents a super-wideband multiple-input multiple-output (SWB MIMO) antenna with low profile, low mutual coupling, high gain and compact size for microwave and millimeter wave (mm-wave) fifth-generation (5G) applications. A single antenna is a simple elliptical-square shape with a small physical size of 20 × 20 × 0.787 mm3. The combination of both square and elliptical shapes results in an exceptionally broad impedance bandwidth spanning from 3.4 to 70 GHz. An-tenna dimensions are optimized using the trust-region algorithm to enhance its impedance band-width, and maintain the gain within a predefined limit across the entire band. For that purpose, regularized merit function is defined, which permits to control both the single antenna reflection response and gain. Subsequently, the SWB MIMO system is constructed with four radiators ar-ranged orthogonally. This arrangement results in high isolation, better than 20 dB, over a fre-quency band from 3.4 to 70 GHz band. Further, the system achieves an average gain of approxi-mately 7 dB below 45 GHz and a maximum gain equal to 12 dB for 70 GHz. The system exhibits excellent diversity performance throughout the entire bandwidth, as evidenced by the low enve-lope correlation coefficient (ECC) (<3∙10−3), total active reflection coefficient (TARC) (≤−10 dB), and channel capacity loss (CCL) (<0.3 bit/s/Hz) metrics, as well as high diversity gain (DG) of approxi-mately 10 dB. Experimental validation of the developed SWB MIMO demonstrates a good match-ing between the measurements and simulations.
Design and Optimization of Metamaterial-Based 5G Millimeter Wave Antenna for Gain Enhancement
- Bashar Esmail
- Sławomir Kozieł
2023 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS
In this brief, a low profile, broadband, high-gain antenna array based on optimized metamaterials (MMs) with dual-beam radiation is reported for 5G millimeters wave (mm-wave) applications. The design is a simple bow tie operating at a 5G band of 28 GHz. It consists of two bow ties with substrate integrated waveguide (SIW)-based power splitter. A broad impedance bandwidth of 26.3−29.8 GHz is obtained by appropriately combining the resonances of the bow ties and the SIW. Further, the antenna exhibits symmetrical dual-beam radiation at ±25˚ over a broad bandwidth in the end-fire direction due to the arrangement of the two radiators. A MM array has been etched in the same substrate shared with the antenna to improve the gain performance while preserving compact size. The trust-region (TR) gradient-based algorithm is used to optimize the structure dimensions and to achieve a maximum gain of 12.2 dB at 29 GHz. The developed MM-based antenna is validated experimentally with a good matching between the simulated and measured data. The system features a small size, low profile, high gain, broad bandwidth, and dual-beam in the E-plane, demonstrating its suitability for 5G mm-wave indoor scenarios.