Wyniki wyszukiwania dla: MICROWAVE PASTEURIZATION
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Shape control over microwave hydrothermally grown Y2O3:Eu by europium concentration adjustment
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Reduction of Tb4+ ions in luminescent Y2O3:Tb nanorods prepared by microwave hydrothermal method
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Numerically efficient algorithm for compact microwave device optimization with flexible sensitivity updating scheme
PublikacjaAn efficient trust-region algorithm with flexible sensitivity updating management scheme for electromagnetic (EM)-driven design optimization of compact microwave components is proposed. During the optimization process, updating of selected columns of the circuit response Jacobian is performed using a rank-one Broyden formula (BF) replacing finite differentiation (FD). The FD update is omitted for directions sufficiently well aligned...
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Accelerated design optimization of miniaturized microwave passives by design reusing and Kriging interpolation surrogates
PublikacjaElectromagnetic (EM) analysis has become ubiquitous in the design of microwave components and systems. One of the reasons is the increasing topological complexity of the circuits. Their reliable evaluation—at least at the design closure stage—can no longer be carried out using analytical or equivalent network representations. This is especially pertinent to miniaturized structures, where considerable EM cross-coupling effects occurring...
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Improved Modeling of Microwave Structures Using Performance-Driven Fully-Connected Regression Surrogate
PublikacjaFast replacement models (or surrogates) have been widely applied in the recent years to accelerate simulation-driven design procedures in microwave engineering. The fundamental reason is a considerable—and often prohibitive—CPU cost of massive full-wave electromagnetic (EM) analyses related to solving common tasks such as parametric optimization or uncertainty quantification. The most popular class of surrogates are data-driven...
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Design specification management with automated decision-making for reliable optimization of miniaturized microwave components
PublikacjaThe employment of numerical optimization techniques for parameter tuning of microwave components has nowadays become a commonplace. In pursuit of reliability, it is most often carried out at the level of full-wave electromagnetic (EM) simulation models, incurring considerable computational expenses. In the case of miniaturized microstrip circuits, densely arranged layouts with strong cross-coupling effects make EM-driven tuning...
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Reduced-cost surrogate modelling of compact microwave components by two-level kriging interpolation
PublikacjaFull-wave electromagnetic (EM) analysis is a versatile tool for evaluating the performance of high-frequency components. Its potential drawback is its high computational cost, inhibiting the execution of EM-driven tasks requiring massive simulations. The applicability of equivalent network models is limited owing to the topological complexity of compact microstrip components because of EM cross-coupling effects. Development of...
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A Generalized SDP Multi-Objective Optimization Method for EM-Based Microwave Device Design
PublikacjaIn this article, a generalized sequential domain patching (GSDP) method for efficient multi-objective optimization based on electromagnetics (EM) simulation is proposed. The GSDP method allowing fast searching for Pareto fronts for two and three objectives is elaborated in detail in this paper. The GSDP method is compared with the NSGA-II method using multi-objective problems in the DTLZ series, and the results show the GSDP method...
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Multi-Fidelity Local Surrogate Model for Computationally Efficient Microwave Component Design Optimization
PublikacjaIn order to minimize the number of evaluations of high-fidelity (“fine”) model in the optimization process, to increase the optimization speed, and to improve optimal solution accuracy, a robust and computational-efficient multi-fidelity local surrogate-model optimization method is proposed. Based on the principle of response surface approximation, the proposed method exploits the multi-fidelity coarse models and polynomial interpolation...
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Enhanced boron doping of thin diamond films grown in deuterium-rich microwave plasma
PublikacjaThe boron-doped diamond thin films were growth in deuterium rich microwave plasma in CVD process. The mechanism of influence of plasma composition on boron doping level was studied using optical emission spectroscopy. Deuterium rich plasma results in an increased dissociation of B2H6 precursor and intense boron-radicals' production. In consequence, a higher doping level of diamond films was observed by means of Laser Induced Breakdown...
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Compressed Projection Bases for Model-Order Reduction of Multiport Microwave Components Using FEM
PublikacjaThis paper presents a projection basis compression technique for generating compact reduced-order models (ROM) in the FE analysis of microwave devices. In this approach redundancy is removed from the projection basis by means of the proper orthogonal decomposition technique applied to the projected system of linear equations. Compression allows for keeping the size of a reduced-order model as small as possible without compromising...
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Rapid design closure of microwave components by means of feature-based optimization and adjoint sensitivities
PublikacjaIn this article, fast design closure of microwave components using feature-based optimization (FBO) and adjoint sensitivities is discussed. FBO is one of the most recent optimization techniques that exploits a particular structure of the system response to “flatten” the functional landscape handled during the optimization process, which leads to reducing its computational complexity. When combined with gradient-based search involving...
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Microwave-assisted synthesis of a TiO2-CuO heterojunction with enhanced photocatalytic activity against tetracycline
PublikacjaA microwave method was used for the synthesis of TiO2-CuO oxide systems. A detailed investigation was made of the effect of the molar ratio of components (TiO2:CuO=9:1, 7:3, 5:5, 3:7, 1:9) on the crystalline structure and morphology. Transmission electron microscopy (TEM) confirmed the presence of octahedral and rod-shaped titania particles and sheet copper(II) oxide particles; moreover, HRTEM analysis indicated the presence of...
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Accelerated multi-objective design of miniaturized microwave components by means of nested kriging surrogates
PublikacjaDesign of microwave components is an inherently multiobjective task. Often, the objectives are at least partially conflicting and the designer has to work out a suitable compromise. In practice, generating the best possible trade‐off designs requires multiobjective optimization, which is a computationally demanding task. If the structure of interest is evaluated through full‐wave electromagnetic (EM) analysis, the employment of...
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A Microwave Sensor with Operating Band Selection to Detect Rotation and Proximity in the Rapid Prototyping Industry
PublikacjaThis paper presents a novel sensor for detecting and measuring angular rotation and proximity, intended for rapid prototyping machines. The sensor is based on a complementary split-ring resonator (CSRR) driven by a conductor-backed coplanar waveguide. The sensor has a planar topology, which makes it simple and cost-effective to produce and accurate in measuring both physical quantities. The sensor has two components, a rotor, and...
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Rapid tolerance‐aware design of miniaturized microwave passives by means of confined‐domain surrogates
PublikacjaThe effects of uncertainties, primarily manufacturing tolerances but also incomplete information about operating conditions or material parameters, can be detrimental to the performance of microwave components. Quantification of such effects is essential to ensure a meaningful evaluation of the structure, in particular, its reliability under imperfect fabrication procedures. The improvement of the circuit robustness can be achieved...
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Tolerance-Aware Optimization of Microwave Circuits by Means of Principal Directions and Domain-Restricted Metamodels
PublikacjaPractical microwave design is most often carried out in the nominal sense. Yet, in some cases, performance degradation due to uncertainties may lead to the system failing to meet the prescribed specifications. Reliable uncertainty quantification (UQ) is therefore important yet intricate from numerical standpoint, especially when the circuit at hand is to be evaluated using electromagnetic (EM) simulation tools. Tolerance-aware...
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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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Algoritmically improved microwave radar monitors breathing more acurrate than sensorized belt
PublikacjaThis paper describes a novel way to measure, process, analyze, and compare respiratory signals acquired by two types of devices: a wearable sensorized belt and a microwave radar-based sensor. Both devices provide breathing rate readouts. First, the background research is presented. Then, the underlying principles and working parameters of the microwave radar-based sensor, a contactless device for monitoring breathing, are described....
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Globalized Simulation-Driven Miniaturization of Microwave Circuits by Means of Dimensionality-Reduced Constrained Surrogates
PublikacjaSmall size has become a crucial prerequisite in the design of modern microwave components. Miniaturized devices are essential for a number of application areas, including wireless communications, 5G/6G technology, wearable devices, or the internet of things. Notwithstanding, size reduction generally degrades the electrical performance of microwave systems. Therefore, trade-off solutions have to be sought that represent acceptable...
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An NO2 sensor based on WO3 thin films for automotive applications in the microwave frequency range
PublikacjaA microwave system dedicated to the detection of nitrogen dioxide in the harsh environment of the Norway highways is proposed. An optimized transmission line type of sensor coated with a tungsten trioxide thin film that changes its electrical properties under NO2 gas exposure is developed. The sensors' response (S) is given in °/GHz and it is calculated based on wideband measurements. The advantage of wideband measurements in comparison...
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Uncertainty Quantification of Additive Manufacturing Post-Fabrication Tuning of Resonator-Based Microwave Sensors
PublikacjaReconfigurability, especially in terms of the ability of adjusting the operating frequency, has become an important prerequisite in the design of modern microwave components and systems. It is also pertinent to microwave sensors developed for a variety of applications such as characterization of material properties of solids or liquids. This paper discusses uncertainty quantification of additive-manufacturing-based post-fabrication...
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Very High Frequency Technique Laboratory - First Step to the World of Microwaves
PublikacjaArtykuł opisuje nowe podejście do zajęć dydaktycznych związanych z przedmiotem Technika Bardzo Wysokich Częstotliwości.
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Spectroscopic study of atmospheric pressure 915 MHz microwave plasma at high argon flow rate
PublikacjaIn this paper results of optical emission spectroscopic (OES) study of atmospheric pressure microwave 915 MHz argon plasma are presented. The plasma was generated in microwave plasma source (MPS) cavity- resonant type. The aim of research was determination of electron excitation temperature Texc gas temperature Tg and electron number density ne. All experimental tests were performed with a gas flow rate of 100 and 200 l/min and...
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Nested Space Mapping Technology for Expedite EM-driven Design of Compact RF/microwave Components
PublikacjaA robust simulation-driven methodology for rapid and reliable design of RF/microwave circuits comprising compact microstrip resonant cells (CMRCs) is presented. We introduce a nested space mapping (NSM) technology, in which the inner space mapping layer is utilized to improve the generalization capabilities of the equivalent circuit model corresponding to a constitutive element of the circuit under consideration. The outer layer...
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Expedited EM-Driven Design of Miniaturized Microwave Hybrid Couplers Using Surrogate-Based Optimization
PublikacjaMiniaturization of microwave hybrid couplers is important for contemporary wireless communication engineering. Using standard computer-aided design methods for development of compact structures is extremely challenging due to a general lack of computationally efficient and accurate simulation models. Poor accuracy of available equivalent circuits results from neglecting parasitic cross-couplings that greatly affect the performance...
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Biopolyols obtained via microwave-assisted liquefaction of lignin: structure, rheological, physical and thermal properties
PublikacjaThe present study examined the application of polyols obtained via microwave-assisted liquefaction of lignin in the production of rigid polyurethane foam. Lignin was liquefed in crude glycerol and 1,4-butanediol at diferent temperatures (130–170 °C), without a catalyst and using various biomass concentrations (15 and 30 wt%). The physicochemical properties, process yield, and FTIR-based identifcation of the obtained polyols were...
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Expedited Multi-Objective Design Optimization of Miniaturized Microwave Structures Using Physics-Based Surrogates
PublikacjaIn this paper, a methodology for fast multi-objective design optimization of compact microwave circuits is presented. Our approach exploits an equivalent circuit model of the structure under consideration, corrected through implicit and frequency space mapping, then optimized by a multi-objective evolutionary algorithm. The correction/optimization of the surrogate is iterated by design space confinement and segmentation based on...
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Strategies for computationally feasible multi-objective simulation-driven design of compact RF/microwave components
PublikacjaMulti-objective optimization is indispensable when possible trade-offs between various (and usually conflicting) design objectives are to be found. Identification of such design alternatives becomes very challenging when performance evaluation of the structure/system at hand is computationally expensive. Compact RF and microwave components are representative examples of such a situation: due to highly compressed layouts and considerable...
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Rapid multi-objective design optimisation of compact microwave couplers by means of physics-based surrogates
PublikacjaThe authors introduce a methodology for fast multi-objective design optimisation of miniaturised microwave couplers. The approach exploits the surrogate-based optimisation paradigm with an underlying low-fidelity model constructed from an equivalent circuit of the structure under consideration, corrected through implicit and frequency space mapping. A fast prediction tool obtained this way is subsequently optimised by a multi-objective...
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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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Microwave-Reactor-Based Preparation of Red Iron Oxide Pigment from Waste Iron Sulfate
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Development of New UV–vis Spectroscopic Microwave-Assisted Method for Determination of Glucose in Pharmaceutical Samples
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Structural and Magnetic Properties of Co‒Mn Codoped ZnO Nanoparticles Obtained by Microwave Solvothermal Synthesis
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Influence of mechanochemical and microwave modification on ion-exchange properties of tin dioxide with respect to uranyl ions
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Low-cost EM-Simulation-based Multi-objective Design Optimization of Miniaturized Microwave Structures
PublikacjaIn this work, a simple yet reliable technique for fast multi-objective design optimization of miniaturized microwave structures is discussed. The proposed methodology is based on point-by-point identification of a Pareto-optimal set of designs representing the best possible trade-offs between conflicting objectives such as electrical performance parameters as well as the size of the structure of interest. For the sake of computational...
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Optical emission spectroscopy of plasma generated by a waveguide-supplied microwave plasma source operated at 915MHz
PublikacjaIn this paper we present the results of an optical emission spectroscopic study of an atmospheric pressure microwave (915 MHz) nitrogen and nitrogen with carbon dioxide (1%) plasma at high working gas flow rate. This study was aimed at determining rotational Trot and vibrational Tvib temperatures of N+2 ions and N2, CN molecules. The plasma was generated in a waveguide-supplied cavity-resonant type microwave plasma source. All...
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Spectroscopic study of atmospheric pressure 915 MHz microwave plasma at high argon flow rate
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A non-quasi-static small-signal model of the four-terminal MOSFET for radio and microwave frequencies.
PublikacjaW pracy zaprezentowano nowy małosygnałowy model tranzystora MOS, w którymuwzględnia się efekt nasycenia prędkości nośników. Model jest spójny fizycznie i może być stosowany w analizie dowolnej konfiguracji włączenia tranzystora.
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Luminescence enhancement in nanocrystalline Eu2O3 nanorods – Microwave hydrothermal crystallization and thermal degradation of cubic phase
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Estimating Traffic Intensity Employing Passive Acoustic Radar and Enhanced Microwave Doppler Radar Sensor
PublikacjaInnovative road signs that can autonomously display the speed limit in cases where the trac situation requires it are under development. The autonomous road sign contains many types of sensors, of which the subject of interest in this article is the Doppler sensor that we have improved and the constructed and calibrated acoustic probe. An algorithm for performing vehicle detection and tracking, as well as vehicle speed measurement,...
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Constrained multi-objective optimization of compact microwave circuits by design triangulation and pareto front interpolation
PublikacjaDevelopment of microwave components is an inherently multi-objective task. This is especially pertinent to the design closure stage, i.e., final adjustment of geometry and/or material parameters carried out to improve the electrical performance of the system. The design goals are often conflicting so that the improvement of one normally leads to a degradation of others. Compact microwave passives constitute a representative case:...
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Assessment of the devulcanization process of EPDM waste from roofing systems by combined thermomechanical/microwave procedures
PublikacjaEthylene-propylene-diene rubber (EPDM) is a elastomer widely used in common industrial applications. EPDM can be shaped into sheets and employed as isolating material for roofing systems. In this study, scraps of EPDM from commercial, industrial and residential roofing systems were treated by combined thermo-mechanical and microwave devulcanization processes including peroxide of benzoyl (BPO). The devulcanized EPDM (Dev-EPDM)...
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Comparing traffic intensity estimates employing passive acoustic radar and microwave Doppler radar sensor
PublikacjaThe purpose of our applied research project is to develop an autonomous road sign with built-in radar devices of our design. In this paper, we show that it is possible to calibrate the acoustic vector sensor so that it can be used to measure traffic volume and count the vehicles involved in the traffic through the analysis of the noise emitted by them. Signals obtained from a Doppler radar are used as a reference source. Although...
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Optimization-Based Robustness Enhancement of Compact Microwave Component Designs with Response Feature Regression Surrogates
PublikacjaThe ability to evaluate the effects of fabrication tolerances and other types of uncertainties is a critical part of microwave design process. Improving the immunity of the device to parameter deviations is equally important, especially when the performance specifications are stringent and can barely be met even assuming a perfect manufacturing process. In the case of modern miniaturized microwave components of complex topologies,...
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Selection of circuit geometry for miniaturized microwave components based on concurrent optimization of performance and layout area
PublikacjaThe paper presents a framework for automated EM-driven circuit geometry selection of miniaturized microwave components. Selection of a particular layout is based directly on miniaturization rates achieved for a set of candidate circuit geometries. Size reduction of the considered structures is obtained by replacing their main building blocks (i.e., conventional transmission lines) with slow-wave composite cells and meander lines....
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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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Computationally efficient two-objective optimization of compact microwave couplers through corrected domain patching
PublikacjaFinding an acceptable compromise between various objectives is a necessity in the design of contemporary microwave components and circuits. A primary reason is that most objectives are at least partially conflicting. For compact microwave structures, the design trade-offs are normally related to the circuit size and its electrical performance. In order to obtain comprehensive information about the best possible trade-offs, multi-objective...
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A Multifunctional Microwave Filter/Sensor Component Using a Split Ring Resonator Loaded Transmission Line
PublikacjaThis research is focused on the design and realiza2 tion of a microwave component with multifunctional filter/sensor 3 operation using a resonator-loaded transmission line (TL). It is 4 shown that while the structure acts as a bandstop filter, the 5 phase of the reflection coefficient from the loading resonator(s) 6 on a movable layer can be used for displacement sensing, thus 7 allowing for combining filtering with sensing in...
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Rapid Yield Optimization of Miniaturized Microwave Passives by Response Features and Variable-Fidelity EM Simulations
PublikacjaThe operation of high-frequency devices, including microwave passive components, can be impaired by fabrication tolerances but also incomplete knowledge concerning operating conditions (temperature, input power levels) and material parameters (e.g., substrate permittivity). Although the accuracy of manufacturing processes is always limited, the effects of parameter deviations can be accounted for in advance at the design phase...