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Wyniki wyszukiwania dla: MICROWAVE TREATMENT
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Microwave treatment in waste rubber recycling – recent advances and limitations
PublikacjaEnvironmentally-friendly microwave heating is increasingly used in polymer chemistry and technology. The selectivity and highly efficiency in the heat transfer present a huge advantage in systems based on recycling, improving their productivity and economic competitiveness. In case of the industrial recycling of waste rubbers, especially end-of-life tires, microwave-induced devulcanization and pyrolysis are nowadays considered...
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FTIR spectroscopic and thermogravimetric characterization of ground tyre rubber devulcanized by microwave treatment
PublikacjaIn this work, the phenomena involved in the microwave devulcanization of ground tyre rubber (GTR) were investigated. Three types of GTR with different content of organic compounds (elastomers, plasticizers, etc.), carbon black and ash have been studied. The chemical structure of GTR before and after a microwave devulcanization process was analyzed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA)...
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Synergistic Effects of Bitumen Plasticization and Microwave Treatment on Short-Term Devulcanization of Ground Tire Rubber
PublikacjaGround tire rubber (GTR) was mechano-chemically modified with road bitumen 160/220 and subsequently treated using a microwave radiation. The combined impact of bitumen 160/220 content and microwave treatment on short-term devulcanization of GTR was studied by thermal camera, wavelength dispersive X-ray fluorescence spectrometry (WD-XRF), static headspace, and gas chromatography-mass spectrometry (SHS-GC-MS), thermogravimetric analysis...
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Influence of microwave treatment conditions of GTR on physico-mechanical and structural properties of NBR/NR/GTR composites
PublikacjaThe increasing amount of tires used in the industry induces the researchers to find alternatives to the recycling of the end-of-life tires. Several alternatives in order to application of ground tire rubber GTR include their incorporation as a filler in composites. The main issue in this approach is the lack of compatibility between GTR and polymer matrix. In order to solve this problem the devulcanization by microwaves has been...
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Microwave heat treatment application to pasteurization of human milk
PublikacjaA prototype of microwave pasteurizer has been proposed as an alternative for holder pasteurization (HP) routinely used in Human Milk Bank (HMB), ensuring microbiological safety of human milk (HM). It was shown that the time of heat generation was about 15–16 min shorter by applying the microwave than in HP. Total inactivation of heat-sensitive bacteria Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus...
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Microwave plasma treatment of simulated biomass syngas: Interactions between the permanent syngas compounds and their influence on the model tar compound conversion
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Effect of microwave and convection heating on selected nutrients of human milk
PublikacjaThe aim of this study was to determine the influence of the microwave heating method (MWH) on selected determinants of the nutritional value of human milk (HM) and compare to the effect exerted by the standard convection heating (CH) method, including holder pasteurization (HoP). It was showed that using MWH under conditions assumed to ensure microbiological safety, changes in the level of the nutrients were not observed. In these...
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Mechanism of Reduced Sintering Temperature of Al2O3–ZrO2 Nanocomposites Obtained by Microwave Hydrothermal Synthesis
PublikacjaA novel method to obtain Al2O3–ZrO2 nanocomposites is presented. It consists of the co-precipitation step of boehmite (AlO(OH)) and ZrO2, followed by microwave hydrothermal treatment at 270 ◦ C and 60 MPa, and by calcination at 600 ◦ C. Using this method, we obtained two nanocomposites: Al2O3–20 wt % ZrO2 and Al2O3–40 wt % ZrO2. Nanocomposites were characterized by Fourier transformed infrared spectroscopy, Raman spectroscopy,...
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Tuning of the Electrochemical Properties of Transparent Fluorine-doped Tin Oxide Electrodes by Microwave Pulsed-plasma Polymerized Allylamine
PublikacjaWe report here the dry, one-step, and low-temperature modification of FTO surfaces using pulsed plasma polymerization of allylamine (PPAAm). PPAAm/FTO surfaces were characterized by X-ray photoelectron spectroscopy, spectroscopic ellipsometry, and contact angles to understand the morphological, structural, and optical properties. FTO were coated with a very thin layer of adherent cross-linked, pinhole-, and additive-free allylamine...
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The influence of sterilization with EnbioJet Microwave Flow Pasteurizer on composition and bioactivity of aronia and blue-berried honeysuckle juices
PublikacjaIn this study, fruit juices that are rich sources of anthocyanins, obtained from aronia (Am. chokeberry, Aronia melanocarpa) and blueberry honeysuckle (Lonicera caerulea L. var. edulis) were used to examine the preservation of plant phytochemicals and bioactivity upon sterilization -either thermal, or with an EnbioJet microwave flow pasteurizer. The chemical properties verified included determinations of anthocyanins and other...
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High-performance method of carbon nanotubes modification by microwave plasma for thin composite films preparation
PublikacjaIn this work we present a simple and efficient method of nitrogen plasma modification of carbon nanotubes (CNTs). The process allows for treatment of the nanotubes in the form of powder with quite a high yield (65 mg of CNTs per hour). The modified carbon nanotubes contain approx. 3.8% of nitrogen, mostly in the pyridinic form. Plasma treated CNTs exhibit better dispersibility in water and higher electric capacitance than pristine...
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Errors caused by microwave part of the microwave heating system
PublikacjaPrzedstawiono skrótowo zasadę pracy i konstrukcję systemu do badań naukowych procesów grzania mikrofalowego. Wyprowadzono wyrażenie opisujące wartość średniokwadratową błędu pomiaru energii mikrofalowej i przeanalizowano składowe błędu pomiaru powodowane przez rzeczywiście występujące w układzie pomiarowym parametry techniczne jego części mikrofalowej.
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Unraveling a novel microwave strategy to fabricate exposed {001}/{101} facets anatase nanocrystals: Potential for use to the elimination of environmentally toxic metronidazole waste
PublikacjaThis study present a novel microwave strategy to fabricate highly active anatase particles, exposing {101} and {001} facets. Microwave treatment time was shown to determine the growth of crystals in a certain direction. To the best of our knowledge, it is the first report revealing that the contact time of TiO2 crystals with fluorine ions during the microwave process affects the formed morphology, in particular exposed facets ratio....
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Surface modification of PMMA polymer and its composites with PC61BM fullerene derivative using an atmospheric pressure microwave argon plasma sheet
PublikacjaThis paper presents the results of experimental investigations of the plasma surface modification of a poly(methyl methacrylate) (PMMA) polymer and PMMA composites with a [6,6]-phenyl-C61-butyric acid methyl ester fullerene derivative (PC61BM). An atmospheric pressure microwave (2.45 GHz) argon plasma sheet was used. The experimental parameters were: an argon (Ar) flow rate (up to 20 NL/min), microwave power (up to 530 W), number...
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Kriging Models for Microwave Filters
PublikacjaSurrogate modeling of microwave filters’ response is discussed. In particular, kriging is used to model either the scattering parameters of the filter or the rational representation of the filter’s characteristics. Surrogate models for these two variants of kriging are validated in solving a microwave filter optimization problem. A clear advantage of surrogate models based on the rational representation over the models based on scattering...
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Evaluation of the potential of Microwave Plasma–Atomic Emission Spectrometry for trace elements leaching assessment from the concrete matrix with sewage sludge ash additives
PublikacjaThe management of ash generated during the thermal utilization of sewage sludge is a significant environmental problem requiring an effective technological solution. One alternative way to dispose of sewage sludge is to bind it in concrete as a substitute for part of the aggregate. The properties of the C-S-H phase enable effective immobilization of harmful substances that sewage sludge contains. The amount of individual compounds...
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Microwave-assisted silication of potato starch
PublikacjaSilication of potato starch was performed by microwave irradiation and convectional heating of starch with sodium metasilicate. The study has shown that microwaves offered more selective silication thanconvectional heating. Depending on the dose of metasilicate products of either monoesterification or crosslinking esterification were formed. Increase in the amount of the silicating agent favoured crosslinking of starch. In the...
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Synthesis of amides under microwave irradiation
PublikacjaAmides belong to the most important carboxylic acid derivatives. They are constituents of natural compounds like peptides and proteins. They found applications in many branches of science and industry, especially in pharmaceutical and polymer science. Conventional procedures for amide preparation involve reaction between amine and carboxylic acid or their more active derivatives such as acid chlorides, acid anhydrides or esters....
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Microwave radiation in the synthesis of urethane prepolymers
PublikacjaThis paper describes the use of microwave radiation in the synthesis of urethane prepolymers in bulk (without solvent). The prepolymers were synthesized using 1,6-hexamethylene diisocyanate (HDI) and poly (ε-caprolactone) diol (PCL) at a molar ratio of 4:1. The reaction was carried out without a catalyst in the reactor with a conventional heating system (oil bath) or in the microwave reactor (MW Reactor NOVA 09) at temperatures...
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Low-Cost Surrogate Models for Microwave Filters
PublikacjaA novel low-cost kriging-based multivariable parametric macromodeling technique for microwave filters is presented. Kriging is used to model both the residues and poles of a microwave filter's reflection coefficient, and the zeros of the transmission coefficient. The proposed residue-pole-zero (RPZ) technique is demonstrated to efficiently model a high dimensional (8D) microwave filter with pseudoelliptic characteristics.
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Near Field Coupled Wireless Microwave Sensor
PublikacjaThis paper presents a wireless planar microwave sensor operating at industrial scientific and medical (ISM) frequency for the detection of dielectric materials. The microwave sensor consists of a reader (ground defected microstrip coupled line) and a passive tag where a complementary split-ring resonator (CSRR) is made on the commercially available copper-foil. The CSRR is a peel-off type tag that is excited using the near field...
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Low cost microwave X-band generator
PublikacjaA low cost microwave X-band generator for educational purposes was designed and built. Its simple construction and user's interface makes it suitable for a student laboratory.The generator is based on a single frequency conversion concept. It uses a digitally tunable PLL chip for intermediate frequency generation and an active frequency multiplier for frequency conversion. The generator covers 9,7 - 11 GHz part of the X frequency...
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Design of Microwave-Based Angular Displacement Sensor
PublikacjaThis letter presents a novel microwave-based rotation sensor having a wide dynamic range to detect and measure the angular displacement in terms of the change in resonant frequency. The proposed sensor is based on the microstrip technology, where a rotor comprised of a complementary splitring resonator (CSRR) placed on the ground plane of the microstrip line is free to rotate around its axis. The mechanical rotation of CSRR determines...
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Effect of Microwave Radiation Power on the Size of Aggregates of ZnO NPs Prepared Using Microwave Solvothermal Synthesis
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Microwave Ring Resonator Based Pressure Sensor
PublikacjaThis paper demonstrates a microwave pressure sensor, which is based on microstrip line-fed ring resonators. The first ring resonator is loaded with the concentric cylindrical shafts, while the same number of the hollow shanks as the shafts are mounted on the second ring resonator. The arrangement of the cylindrical shaft and hollow shank allows for mechanical movement between two substrates while maintaining electrical contact....
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Preparation of exfoliated graphite by microwave irradiation
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Microwave-assisted boration of potato starch
PublikacjaZiarnistą skrobię ziemniaczaną boranowano za pomocą kwasu borowego i dziesięciowodnego tetraboranu sodu (boraksu) w reakcji wspomaganej mikrofalami. Określono wpływ stosunku substratów oraz czasu trwania i mocy naświetlania na stopień estryfikacji (DE) produktów. Maksymalna wartość DE w próbkach skrobi boranowanej kwasem wyniosła 0,27, a boranowanej boraksem 0,18. Ustalono, że chociaż zmodyfikowana skrobia, o strukturze estrów...
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A review of amide bond formation in microwave organic synthesis
PublikacjaMicrowave-Assisted Organic Synthesis (MAOS) is one of the most current trends in organic chemistry. Herein, both the most popular and new approaches in microwave-syntheses of very important linkage in Nature - amide bond - are overviewed and compared with conventional synthetic routes.
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Modelling of dielectric properties of BiNbO4-based microwave ceramics
PublikacjaIn the present paper results of the studies devoted to computer simulations of dielectric response of electroceramics in a frequency domain as well as analysis of the experimental data are given. As an object of investigations BiNbO4-based microwave ceramics was taken. Simulations of the hypothetical impedance response of the ceramic system were performed under assumption of the brick-layer model. A strategy for analysis and modelling...
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Microwave-assisted synthesis of zinc derivatives of potato starch
PublikacjaZincatated potato starch was prepared in a solid-state, microwave-assisted reaction using generated in situ sodium tetrahydroxozincate [Na2Zn(OH)4]. For comparison, zincatation of starch was also carriedout on convectional heating. Depending on the irradiation conditions, the products of either mono- or crosslinking esterification were formed. Higher power applied at shorter exposition offered products ofmonoesterification, and...
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Zero-Pole Approach in Microwave Passive Circuit Design
PublikacjaIn this thesis, optimization strategies for design of microwave passive structures including filters, couplers, antenna and impedance transformer and construction of various surroogate models utilized to fasten the design proces have been discussed. Direct and hybrid optimization methodologies including space mapping and multilevel algorithms combined with various surrogate models at different levels of fidelity have been utilized...
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Size Reduction of Microwave Couplers by EM-Driven Optimization
PublikacjaThis work addresses simulation-driven design optimization of compact microwave couplers that explicitly aims at circuit footprint area reduction. The penalty function approach allows us to minimize the area of the circuit while ensuring a proper power division between the output ports and providing a sufficient bandwidth with respect to return loss and isolation around the operating frequency. Computational cost of the optimization...
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Measurement accuracy of the system to control the microwave heating.
PublikacjaPrzedstawiono skrótowo zasadę pracy i konstrukcję systemu do badań naukowych procesów grzania mikrofalowego. Wyprowadzono wyrażenie opisujące wartość średniokwadratową błędu pomiaru energii mikrofalowej i przeanalizowano składowe błędu pomiaru powodowane przez rzeczywiście występujące w układzie pomiarowym parametry techniczne jego części mikrofalowej.
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Macromodels in the frequency domain analysis of microwave resonators.
PublikacjaW artykule zaprezentowana jest technika włączania makromodeli do metod siatkowych sformułowanych w dziedzinie częstotliwości.W odróżnieniu do poprzednich, nowy schemat nie wprowadza zależności częstotliwościowej do macierzy systemowej i dzięki temu może być użyta w analizie rezonatorów. Testy numeryczne pokazują wzrost dokładności obliczeń w szerokim zakresie częstotliwości, przy czym właściwości zbieżności iteracyjnego algorytmu...
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Planar Microwave Bragg Reflector Resonant Dielectric Sensor
PublikacjaIn this paper, a periodic structure is used to design a microwave Bragg reflector with the help of hexagonal lattice, which provides a 5 GHz wide stopband between the low-pass band with cut-off frequency 2.6 GHz and the bandpass response with start and stop frequency 7.8 GHz and 10.5 GHz, respectively. A defect in lattice allows passing a narrowband signal at 6 GHz which is found, from the dispersion relation, to be in the region...
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Microwave-assisted preparation of potato starch silicated with silicic acid
PublikacjaApplication of microwave irradiation for the silication of granular potato starch with silicic acid, and the properties of silicated starch were investigated. Potato starch was esterified on 20 min microwave irradiation of starch with silicic acid, applying the power of 450 or 800Wand, for comparison, on 120 min convectional heating of the reagent blend at 100 ◦C. The degree of esterification and the reaction efficiency did not...
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Study of anticorrosion and microwave absprption properties of NiZn ferrite pigments
PublikacjaPurpose - The purpose of this paper is to report the electrochemical verification of anticorrosive properties of NiZn ferrites as pigments in protective coatings and evaluation of their microwave absorbing properties. Design/methodology/approach - Ferrites, represented by formula NixZn(1-x)Fe2O4, where x=0, 0.2, 0.4, 0.6, 0.8, 1.0, were synthesized using a ceramic method. The samples of ferrites were examined by X-ray diffraction...
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Novel MNZ-type microwave sensor for testing magnetodielectric materials
PublikacjaA novel microwave sensor with the mu-near-zero (MNZ) property is proposed for testing magnetodielectric material at 4.5 GHz. The sensor has a double-layer design consisting of a microstrip line and a metal strip with vias on layers 1 and 2, respectively. The proposed sensor can detect a unit change in relative permittivity and relative permeability with a difference in the operating frequency of 45 MHz and 78 MHz, respectively....
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Automated microwave planar filter design with generalized Chebyshev characteristics.
PublikacjaIn this paper a technique of automatization of design of microwave filters with generalized Chebyshev characteristics is presented. A full wave electromagnetic simulator linked with the Matlab computing environment is used to ensure a rigorous numerical analysis while at the same time allowing automatization. To decrease time of optimization and overall design process, the Cauchy interpolation technique was used. An automated design...
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Interactive Application for Visualization of the Basic Phenomena in RF and Microwave Devices
PublikacjaAn interactive computer application visualizing the basic phenomena in RF and microwave devices is presented. Such kind of educational package can be a very helpful tool for the students as well as for the teachers (of electronics and related fields). This paper is focused on three exemplary problems only and involves: movement of electric charge, filtering of electromagnetic waves and interference phenomena in antenna arrays. The...
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Computationally Efficient Design Optimization of Compact Microwave and Antenna Structures
PublikacjaMiniaturization is one of the important concerns of contemporary wireless communication systems, especially regarding their passive microwave components, such as filters, couplers, power dividers, etc., as well as antennas. It is also very challenging, because adequate performance evaluation of such components requires full-wave electromagnetic (EM) simulation, which is computationally expensive. Although high-fidelity EM analysis...
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Frequency-dependent coupling model for microwave band-pass filter
PublikacjaThe goal of this work was to create a circuit model which represents frequency-dependent coupling between microwave resonators. Our models are designed for in-line filters. The frequency-dependent coupling enables one to realize a transmission zero which is not possible in classical approach with frequency independent inverters. In addition, the proposed model allows us to observe out-of-band behavior, e.g. spurious resonance....
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On measurements applied in scientific researches of microwave heating processes
PublikacjaPrzedstawiono trudności techniczne wykonywania pomiarów w systemach gdzie stosuje się duże poziomy mocy mikrofalowej. Omówiono zasadę pracy do badania procesu grzania mikrofalowego oraz wybrane problemy występujące przy realizacji takiego systemu. Uzasadniono celowość prowadzenia przedstawionych rodzajów pomiarów w badaniach procesów grzania mikrofalowego materiałów.
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Internet as a new platform for delivery of microwave CAD services.
PublikacjaZaprezentowano aplikację przeznaczoną do syntezy filtrów rezonatorowych, która jest realizacją nowego sposobu myślenia związanego z rewolucją usług internetowych, które charakteryzują się niskim kosztem tworzenia oraz szybką i bezpieczną dystrybucją. Opisano stworzoną wielowarstwową aplikację, która gwarantuje łatwy, bezpieczny oraz ograniczony dostęp do aplikacji dla szerokiego kręgu osób. Zawarto w niej algorytm szybkiej syntezy...
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The role of hydrogen in microwave plasma valorization of producer gas
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Artificial Neural Networks in Microwave Components and Circuits Modeling
PublikacjaArtykuł dotyczy wykorzystania sztucznych sieci neuronowych (SNN) w projektowaniu i optymalizacji układów mikrofalowych.Zaprezentowano podstawowe zasady i założenia modelowania z użyciem SNN. Możliwości opisywanej metody opisano wykorzystując przykładowyprojekt anteny łatowej. Przedstawiono różne strategie modelowania układów, które wykorzystują możliwości opisywanej metody w połączeniu zwiedzą mikrofalową. Porównano również dokładność...
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Surrogate models and automated cad of passive microwave components
PublikacjaW pracy pokazane zostały techniki modelowania złożonych układów elektronicznych wysokiej częstotliwości. Modele zastępcze mają postać sparametryzowanych modeli matematycznych tworzonych za pomocą schematów interpolacyjnych lub skupionych, pasywnych układów zastępczych dedykowanych analizie w dziedzinie czasu. Do konstrukcji modeli wykorzystywane są wyniki symulacji elektromagnetycznych, co pozwala na osiągnięcie lepszej dokładności...
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Towards automated full-wave design of microwave structures
PublikacjaArtykuł przedstawia problematykę automatycznego projektowania układów mikrofalowych i jego znaczenie. przedstawia stan rynku narzędzi projektowania, pojawiąjące się rozwiązania i przyszłe trendy.
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Magnetic properties of BiFeO3micro-cubes synthesized by microwave agitation
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Reliable Microwave Modeling By Means of Variable-Fidelity Response Features
PublikacjaIn this work, methodologies for low-cost and reliable microwave modeling are presented using variable-fidelity response features. The two key components of our approach are: (i) a realization of the modeling process at the level of suitably selected feature points of the responses (e.g., S-parameters vs. frequency) of the structure at hand, and (ii) the exploitation of variable-fidelity EM simulation data, also for the response...
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Hydrogen production from ethanol In nitrogen microwave plasma At atmospheric pressure
PublikacjaHydrogen seems to be one of the most promising alternative energy sources. It is a renewable fuel as it could be produced from e.g. waste or bio-ethanol. Furthermore hydrogen is compatible with fuel cells and is environmentally clean. In contrast to conventional methods of hydrogen production such as water electrolysis or coal gasification we propose a method based on atmospheric pressure microwave plasma. In this paper we present...
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Rheology of potato starch chemically modified with microwave-assisted reactions
PublikacjaNative potato starch was sulfated, selenated, borated, silicated and zincatated by means of microwave-assisted reactions with varying doses of relevant reagents. Resulting products were characterized involving rheological behavior of pastes, their weight-average molecular weight (Mw), and radius of gyration (Rg). Most of the pastes showed shear-thinning behavior, with the flow behavior index (n) below unity. The pastes of starch...
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Direct Constraint Control for EM-Based Miniaturization of Microwave Passives
PublikacjaHandling constraints imposed on physical dimensions of microwave circuits has become an important design consideration over the recent years. It is primarily fostered by the needs of emerging application areas such as 5G mobile communications, internet of things, or wearable/implantable devices. The size of conventional passive components is determined by the guided wavelength, and its reduction requires topological modifications,...
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The Design of Cavity Resonators and Microwave Filters Applying Shape Deformation Techniques
PublikacjaThis article introduces shape deformation as a new approach to the computer-aided design (CAD) of high-frequency components. We show that geometry deformation opens up new design possibilities and offers additional degrees of freedom in the 3-D modeling of microwave structures. Such design flexibility is highly desirable if the full potential of additive manufacturing (AM) is to be exploited in the fabrication of RF and microwave...
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Reduced-Cost Microwave Modeling Using Constrained Domains and Dimensionality Reduction
PublikacjaDevelopment of modern microwave devices largely exploits full-wave electromagnetic (EM) simulations. Yet, simulation-driven design may be problematic due to the incurred CPU expenses. Addressing the high-cost issues stimulated the development of surrogate modeling methods. Among them, data-driven techniques seem to be the most widespread owing to their flexibility and accessibility. Nonetheless, applicability of approximation-based...
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Efficient Complex Root Finding Algorithm for Microwave and Optical Propagation Problems
PublikacjaArticle relates to the use of innovative root finding algorithm (on a complex plane) to study propagation properties of microwave and optical waveguides. Problems of this type occur not only in the analysis of lossy structures, but also in the study of complex and leaky modes (radiation phenomena). The proposed algorithm is simple to implement and can be applied for functions with singularities and branch cuts in the complex plane...
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Reduced-Cost Constrained Modeling of Microwave and Antenna Components: Recent Advances
PublikacjaElectromagnetic (EM) simulation models are ubiquitous in the design of microwave and antenna components. EM analysis is reliable but CPU intensive. In particular, multiple simulations entailed by parametric optimization or uncertainty quantification may considerably slow down the design processes. In order to address this problem, it is possible to employ fast metamodels. Here, the popular solution approaches are approximation...
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Fast geometry scaling of miniaturized microwave couplers with power split correction
PublikacjaRedesigning a microwave circuit for various operating conditions is a practically important yet challenging problem. The purpose of this article is development and presentation of a technique for fast geometry scaling of miniaturized microwave couplers with respect to operating frequency. Our approach exploits an inverse surrogate model constructed using several reference designs that are optimized for a set of operating frequencies...
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A new approach to a fast and accurate design of microwave circuits with complex topologies
PublikacjaA robust simulation-driven design methodology of microwave circuits with complex topologies has been presented. The general method elaborated is suitable for a wide class of N-port unconventional microwave circuits constructed as a deviation from classic design solutions. The key idea of the approach proposed lies in an iterative redesign of a conventional circuit by a sequential modification and optimisation of its atomic building...
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Rapid multi-objective simulation-driven design of compact microwave circuits
PublikacjaA methodology for rapid multi-objective design of compact microwave circuits is proposed. Our approach exploits point-by-point Pareto set identification using surrogate-based optimization techniques, auxiliary equivalent circuit models, and space mapping as the major model correction method. The proposed technique is illustrated and validated through the design of a compact rat-race coupler. A set of ten designs being trade-offs...
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A Novel Synthesis Technique for Microwave Bandpass Filters with Frequency-Dependent Couplings
PublikacjaThis paper presents a novel synthesis technique for microwave bandpass filters with frequency-dependent couplings. The proposed method is based on the systematic extraction of a dispersive coupling coefficient using an optimization technique based on the zeros and poles of scattering parameters representing two coupled resonators.The application of this method of synthesis is illustrated using two examples involving four and five-pole...
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Fast Full-Wave Multilevel Zero-Pole Optimization of Microwave Filters
PublikacjaA new concept is proposed for the full-wave computer-aided design of microwave filters. The method consists of two stages and operates on the zeros and poles of the transfer function and their derivatives. These quantities are evaluated from the response computed by a full-wave electromagnetic solver with two levels of accuracy. The two stages make use of different models that are optimized using a low-accuracy electromagnetic...
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Effect of convection and microwave heating on the retention of bioactive components in human milk
PublikacjaBioactive substances are very important components of human milk (HM), especially for premature newborns. The effects of convection (CH) and microwave heating (MWH) at 62.5 and 66 °C, on the level of selected bioactive components of HM: lysozyme (LZ), lactoferrin (LF), secretory immunoglobulin A (sIgA), basal lipase (BL), cytokine TGF-2, vitamin C and total antioxidant capacity (TAC) was compared. Regardless of the used heating methods...
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Rapid dimension scaling of compact microwave couplers with power split correction
PublikacjaIn this paper, a technique for rapid re-design ofcompact microwave couplers with respect to operating frequency is discussed. Our methodology involves an inverse surrogate model setup using several reference designs optimized (at the level of equivalent circuit representation of the coupler) for a set of operating frequencies within a range of interest. The surrogate establishes the relationship between the operating frequency...
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Metamaterial-Based Sub-Microwave Electromagnetic Field Energy Harvesting System
PublikacjaThis paper presents the comprehensive analysis of the sub-microwave, radio frequency band resonant metastructures’ electromagnetic properties with a particular emphasis on the possibility of their application in energy harvesting systems. Selected structures based on representative topologies of metamaterials have been implemented in the simulation environment. The models have been analyzed and their substitute average electromagnetic...
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Application of atmospheric pressure microwave plasma source for hydrogen production from ethanol
PublikacjaIn contrast to conventional technologies of hydrogen production like water electrolysis or coal gasification we propose a method based on the atmospheric pressure microwave plasma. In this paper we present results of the experimental investigations of the hydrogen production from ethanol in the atmospheric pressure plasma generated in waveguidesupplied cylindrical type nozzleless microwave (915 MHz and 2.45 GHz) plasma source (MPS)....
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Multi-objective optimization of microwave couplers using corrected domain patching
PublikacjaPractical design of microwave components and circuits is a compromise between various, often conflicting objectives. In case of compact structures, the trade-offs are typically concerned with the circuit size and its electrical performance. Comprehensive information about the best possible trade-offs can be obtained by means of multi-objective optimization. In this paper, we propose a computationally efficient technique for identifying...
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Accurate simulation-driven modeling and design optimization of compact microwave structures
PublikacjaCost efficient design optimization of microwave structures requires availability of fast yet reliable replacement models so that multiple evaluations of the structure at hand can be executed in reasonable timeframe. Direct utilization of full-wave electromagnetic (EM) simulations is often prohibitive. On the other hand, accurate data-driven modeling normally requires a very large number of training points and it is virtually infeasible...
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Multivariate models of inter-resonator couplings for microwave filter synthesis
PublikacjaArtykuł przedstawia technikę budowy modeli częstotliwości rezonansowej, współczynnika sprzężenia między rezonatorami oraz sprzężenia ze źródłem/obciążeniem. Przedstawiony jest model siedmiu zmiennych uwzglęgniający topologię rezonatorów. Na podstawie modelu wykonana została synteza filtrów mikrofalowych.
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Study of anticorrosion and microwave absorption properties of NiZn ferrite pigments
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A Novel Reactor for Microwave Hydrothermal Scale-up Nanopowder Synthesis
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Microwave solvothermal synthesis and characterization of manganese-doped ZnO nanoparticles
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Hydrothermal, microwave and mechanochemical modification of amorphous zirconium phosphate structure
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Y2O3:Eu nanocrystals as biomarkers prepared by a microwave hydrothermal method
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A New Microwave Ceramic – Polymer Composite with 0-3 Connectivity
PublikacjaGoal of the present research was to fabricate and study two-phase BiNbO4//PVDF composites with 0-3 connectivity. Such composite consists of there-dimensionally connected polymer matrix loaded with dielectric ceramic particles. In the present case BiNbO4 powder acted as an active phase (dispersed phase) whereas polyvinylidene fluoride (PVDF) acted as a non-active (passive) phase (matrix). BiNbO4//PVDF composites with the volume...
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A Highly Sensitive Planar Microwave Sensor for Detecting Direction and Angle of Rotation
PublikacjaThis article presents a technique based on a modified complementary split-ring resonator (CSRR) to detect angular displacement and direction of rotation with high resolution and sensitivity over a wide dynamic range. The proposed microwave planar sensor takes advantage of the asymmetry of the sensor geometry and measures the angle of rotation in terms of the change in the relative phase of the reflection coefficients. The sensor...
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Inverse Modeling and Optimization of CSRR-based Microwave Sensors for Industrial Applications
PublikacjaDesign optimization of multivariable resonators is a challenging topic in the area of microwave sensors for industrial applications. This paper proposes a novel methodology for rapid re-design and parameter tuning of complementary split-ring resonators (CSRRs). Our approach involves inverse surrogate models established using pre-optimized resonator data as well as analytical correction techniques to enable rapid adjustment of geometry...
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Rapid Microwave Design Optimization in Frequency Domain Using Adaptive Response Scaling
PublikacjaIn this paper, a novel methodology for cost-efficient microwave design optimization in the frequency domain is proposed. Our technique, referred to as adaptive response scaling (ARS), has been developed for constructing a fast replacement model (surrogate) of the high-fidelity electromagnetic-simulated model of the microwave structure under design using its equivalent circuit (low-fidelity model). The basic principle of ARS is...
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Step on It Bringing Fullwave Finite-Element Microwave Filter Design up to Speed
PublikacjaThere are many steps in the design of a microwave filter: mathematically describing the filter characteristics, representing the circuit as a network of lumped elements or as a coupling matrix, implementing the distributed elements, finding the initial dimensions of the physical structure, and carrying out numerical tuning using electromagnetic (EM) simulators. The whole process is painstaking and time-consuming, and it requires...
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Inverse surrogate modeling for low-cost geometry scaling of microwave and antenna structures
PublikacjaPurpose–The purpose of this paper is to investigate strategies for expedited dimension scaling ofelectromagnetic (EM)-simulated microwave and antenna structures, exploiting the concept of variable-fidelity inverse surrogate modeling.Design/methodology/approach–A fast inverse surrogate modeling technique is described fordimension scaling of microwave and antenna structures. The model is established using referencedesigns obtained...
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Rapid optimization of compact microwave passives using kriging surrogates and iterative correction
PublikacjaDesign of contemporary microwave components is—in a large part—based on full-wave electromagnetic (EM) simulation tools. The primary reasons for this include reliability and versatility of EM analysis. In fact, for many microwave structures, notably compact components, EM-driven parameter tuning is virtually imperative because traditional models (analytical or network equivalents) are unable to account for the cross-coupling effects,...
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Expedited Optimization of Passive Microwave Devices Using Gradient Search and Principal Directions
PublikacjaOver the recent years, utilization of numerical optimization techniques has become ubiquitous in the design of high-frequency systems, including microwave passive components. The primary reason is that the circuits become increasingly complex to meet ever growing performance demands concerning their electrical performance, additional functionalities, as well as miniaturization. Nonetheless, as reliable evaluation of microwave device...
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Global Design Optimization of Microwave Circuits Using Response Feature Inverse Surrogates
PublikacjaModern microwave design has become heavily reliant on full-wave electromagnetic (EM) simulation tools, which are necessary for accurate evaluation of microwave components. Consequently, it is also indispensable for their development, especially the adjustment of geometry parameters, oriented towards performance improvement. However, EM-driven optimization procedures incur considerable computational expenses, which may become impractical...
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Globalized parametric optimization of microwave components by means of response features and inverse metamodels
PublikacjaSimulation-based optimization of geometry parameters is an inherent and important stage of microwave design process. To ensure reliability, the optimization process is normally carried out using full-wave electromagnetic (EM) simulation tools, which entails significant computational overhead. This becomes a serious bottleneck especially if global search is required (e.g., design of miniaturized structures, dimension scaling over...
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Low-Cost Surrogate Modeling of Miniaturized Microwave Components Using Nested Kriging
PublikacjaIn the paper, a recently reported nested kriging methodology is employed for modeling of miniaturized microwave components. The approach is based on identifying the parameter space region that contains high-quality designs, and, subsequently, rendering the surrogate in this subset. The results obtained for a miniaturized unequal-power-split rat-race coupler and a compact three-section impedance transformer demonstrate reliability...
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Fast Design Closure of Compact Microwave Components by Means of Feature-Based Metamodels
PublikacjaPrecise tuning of geometry parameters is an important consideration in the design of modern microwave passive components. It is mandatory due to limitations of theoretical design methods unable to quantify certain phenomena that are important for the operation and performance of the devices (e.g., strong cross-coupling effects in miniaturized layouts). Consequently, the initial designs obtained using analytical or equivalent network...
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GPU Acceleration of Multilevel Solvers for Analysis of Microwave Components With Finite Element Method
PublikacjaThe letter discusses a fast implementation of the conjugate gradient iterative method with ${rm E}$-field multilevel preconditioner applied to solving real symmetric and sparse systems obtained with vector finite element method. In order to accelerate computations, a graphics processing unit (GPU) was used and significant speed-up (2.61 fold) was achieved comparing to a central processing unit (CPU) based approach. These results...
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Expedited Variable-Resolution Surrogate Modeling of Miniaturized Microwave Passives in Confined Domains
PublikacjaDesign of miniaturized microwave components is largely based on computational models, primarily, full-wave electromagnetic (EM) simulations. EM analysis is capable of giving an accurate account for cross-coupling effects, substrate and radiation losses, or interactions with environmental components (e.g., connectors). Unfortunately, direct execution of EM-based design tasks such as parametric optimization or uncertainty quantification,...
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A Goal-Oriented Error Estimator for Reduced Basis Method Modeling of Microwave Devices
PublikacjaThis letter proposes a novel a-posteriori error estimator suitable for the reduced order modeling of microwave circuits. Unlike the existing error estimators based on impedance function residuals, the new one exploits the residual error associated with the computation of the scattering matrix. The estimator can be effectively used in the Reduced Basis Method (RBM) to automatically generate reduced-order models. The results of numerical...
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Fast multi-criterial statistical analysis and design optimization of compact microwave couplers
Publikacja—A rapid statistical analysis and yield estimation of compact microwave couplers involving multiple performance parameters has been presented. The analysis is realized using a fast surrogate model representing appropriate characteristic points of the coupler response. Because of less nonlinear dependence of the characteristic points on the structure geometry (compared to the original response, i.e., S-parameters vs. frequency),...
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A Compact and Lightweight Microwave Tilt Sensor Based on an SRR-Loaded Microstrip Line
PublikacjaIn this paper, the symmetry property of split ring resonators (SRRs) is exploited to develop a tilt sensor. The sensor is composed of an SRR-loaded microstrip line operating at microwave frequencies. It is shown that the depth of notch in the reflection characteristic of the microstrip is a function of the tilt angle of the SRR. Thus, it can be used for sensing inclination. The sensor benefits from very compact size and light weight....
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Nested Kriging Surrogates for Rapid Multi-Objective Optimization of Compact Microwave Components
PublikacjaA procedure for rapid EM-based multi-objective optimization of compact microwave components is presented. Our methodology employs a recently developed nested kriging modelling to identify the search space region containing the Pareto-optimal designs, and to construct a fast surrogate model. The latter permits determination of the initial Pareto set, further refined using a separate surrogate-assisted process. As an illustration,...
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Design centering of compact microwave components using response features and trust regions
PublikacjaFabrication tolerances, as well as uncertainties of other kinds, e.g., concerning material parameters or operating conditions, are detrimental to the performance of microwave circuits. Mitigating their impact requires accounting for possible parameter deviations already at the design stage. This involves optimization of appropriately defined statistical figures of merit such as yield. Alt-hough important, robust (or tolerance-aware)...
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Fast surrogate-assisted simulation-driven design of compact microwave hybrid couplers
PublikacjaThis work presents a robust methodology for expedited simulation-driven design optimization of compact microwave hybrid couplers. The technique relies on problem decomposition, and a bot-tom–up design strategy, starting from the level of basic building blocks of the coupler, and finishing with a tuning procedure that exploits a fast surrogate model of the entire structure. The latter is constructed by cascading local response surface...
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Nested Space Mapping Technique for Design and Optimization of Complex Microwave Structures with Enhanced Functionality
PublikacjaIn this work, we discuss a robust simulation-driven methodology for rapid and reliable design of complex microwave/RF circuits with enhanced functionality. Our approach exploits nested space mapping (NSM) technology, which is dedicated to expedite simulation-driven design optimization of computationally demanding microwave structures with complex topologies. The enhanced func-tionality of the developed circuits is achieved by means...
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Efficient Multi-Fidelity Design Optimization of Microwave Filters Using Adjoint Sensitivity
PublikacjaA simple and robust algorithm for computationally efficient design optimiza-tion of microwave filters is presented. Our approach exploits a trust-region (TR)-based algorithm that utilizes linear approximation of the filter response obtained using adjoint sensitivity. The algorithm is sequentially executed on a family of electromagnetic (EM)-simulated models of different fidelities, starting from a coarse-discretization one, and...
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The effect of convective heating and microwave heating on antioxidant enzymes in pooled mature human milk
PublikacjaThe effects of convective and microwave heating at constant temperature (62.5, 66 and 70 °C) on the activity of antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPx) in pooled mature human milk were compared. Activities of the enzymes were determined using spectrophotometric kits. Activity of GPx decreased significantly in the first stage of heating when milk samples were warmed to pasteurisation...
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Expedited two-objective dimension scaling of compact microwave passives using surrogate models
PublikacjaGeometry scaling of compact microwave structures is a challenging problem because of complex relationships between the physical dimensions and electrical characteristics, mostly caused by considerable cross-couplings in densely arranged layouts. Here, a procedure for expedited dimension scaling of compact microwave couplers with respect to two independent criteria has been presented. Our approach involves inverse surrogate models...
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Rapid Simulation-Driven Multiobjective Design Optimization of Decomposable Compact Microwave Passives
PublikacjaIn this paper, a methodology for fast multiobjective optimization of the miniaturized microwave passives has been presented. Our approach is applicable to circuits that can be decomposed into individual cells [e.g., compact microstrip resonant cells (CMRCs)]. The structures are individually modeled using their corresponding equivalent circuits and aligned with their accurate, EM simulated...
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Expedited Geometry Scaling of Compact Microwave Passives by Means of Inverse Surrogate Modeling
PublikacjaIn this paper, the problem of geometry scaling of compact microwave structures is investigated. As opposed to conventional structures (i.e., constructed using uniform transmission lines), re-design of miniaturized circuits (e.g., implemented with artificial transmission lines, ATSs) for different operating frequencies is far from being straightforward due to considerable cross-couplings between the circuit components. Here, we...