Search results for: canonical circuit
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Warunek zwarciowy SkQ/Sn>=20 ograniczeniem rozwoju OZE
PublicationW referacie omówiono zagadnienia związane z warunkiem zwarciowym, czyli ilorazem mocy zwarciowej w rozpatrywanym miejscu przyłączenia do sieci elektroenergetycznej źródła energii i mocy znamionowej tego źródła. Wskazano jego pochodzenie oraz przedyskutowano zasadność jego stosowania w analizach przyłączeniowych.
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Hybrid Technique Combining the FDTD Method and Its Convolution Formulation Based on the Discrete Green's Function
PublicationIn this letter, a technique combining the finite-difference time-domain (FDTD) method and its formulation based on the discrete Green's function (DGF) is presented. The hybrid method is applicable to inhomogeneous dielectric structures that are mutually coupled with wire antennas. The method employs the surface equivalence theorem in the discrete domain to separate the problem into a dielectric domain simulated using the FDTD method...
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Application of the discrete Green's function-based antenna simulations for excitation of the total-field/scattered-field interface in the FDTD method
PublicationIn this article, the discrete Green's function formulation of the finite-difference time-domain (DGF-FDTD) method is proposed for simulation of wire antennas irradiating inhomogeneous dielectric scatterers. Surface equivalence theorem in the discrete domain is used to separate the problem into an inhomogeneous domain and a wire antenna that are simulated with the use of FDTD and DGF-FDTD, respectively. Then, the excitation of the...
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The occurrence and role of Nitrospira in nitrogen removal systems
PublicationApplication of the modern microbial techniques changed the paradigm about the microorganisms performing nitrification. Numerous investigations recognized representatives of the genus Nitrospira as a key and predominant nitrite-oxidizing bacteria in biological nutrient removal systems, especially under low dissolved oxygen and substrate conditions. The recent discovery of Nitrospira capable of performing complete ammonia oxidation...
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Implementation of power transformer controlled switching algorithm
PublicationThe article presents two new algorithms of controlled switching the power transformer. The main aim of the paper is to obtain formulas that determine the moments of closing of the circuit breaker poles. The study contains projects of control systems for both algorithms. Mathematical formulas for the time instants of the breaker poles closing were developed on the basis of electric circuit theory and magnetic circuit theory. The...
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The microstructure of aluminium alloys AA1050 and AA7075 subjected to anodic polarization at 8V in KOH electrolyte
Open Research DataThe dataset contains SEM pictures of the microstructure of aluminum alloy AA1050 and AA7075 exposed in aqueous KOH in the pH range between 14–11. Two sets of samples are presented, revealing the topography of the alloys when exposed to aggressive media under open circuit potential conditions as well as when subjected potentiodynamic polarization ranging...
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Results of EIS measuremnts and DRT analysis of SrTi0.30Fe0.70O3-d oxygen electrode at 800 °C and 1% oxygen partial pressure by using three R-CPE fiting elements
Open Research DataThis dataset contains electrochemical impedance spectroscopy and Distribution of Relaxation Times analysis results for symmetrical cell with porous SrTi0.30Fe0.70O3-d oxygen electrodes sintered at 800 °C. EIS spectra were measured at 800 °C and 1% of oxygen partial pressure. EIS and DRT spectra of simmulated three R-CPE elements from equivalent circuit,...
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Results of EIS measuremnts and DRT analysis of SrTi0.30Fe0.70O3-d oxygen electrode at 800 °C and 1% oxygen partial pressure by using two R-CPE fiting elements
Open Research DataThis dataset contains electrochemical impedance spectroscopy and Distribution of Relaxation Times analysis results for symmetrical cell with porous SrTi0.30Fe0.70O3-d oxygen electrodes sintered at 800 °C. EIS spectra were measured at 800 °C and 1% of oxygen partial pressure. EIS and DRT spectra of simmulated two R-CPE elements from equivalent circuit,...
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ESPAR Antenna-Based WSN Node With DoA Estimation Capability
PublicationIn this paper, we present a low-cost energy-efficient electronically steerable parasitic array radiator (ESPAR) antenna-based wireless sensor network (WSN) node designed for IEEE 802.15.4 standard that is capable of performing direction of arrival (DoA) estimation in real-life outdoor environments. To this end, we propose the WSN node architecture, design and realization that utilizes NXP JN5168 radio frequency (RF) wireless transceiver...
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Enhanced Spectroscopic Insight into Acceptor-Modified Barium Strontium Titanate Thin Films Deposited via the Sol–Gel Method
PublicationIn the present paper, composite thin films of barium strontium titanate (BaxSr1−xTiO3) with an acceptor modifier (magnesium oxide—MgO) were deposited on metal substrates (stainless steel type) using the sol–gel method. The composite thin films feature BaxSr1−xTiO3 ferroelectric solid solution as the matrix and MgO linear dielectric as the reinforcement, with MgO concentrations ranging from 1 to 5 mol%. Following thermal treatment...
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The Multiplatform Environment for Simulation and Features Estimation of Mixed-Signal Devices
PublicationThe use of simulation laboratories is gaining popularity in thedomains of engineering programs. However, the experience in teaching showsthat the simulation itself is not very effective in didactic processes. Teachingprocesses in thefield of specialist subjects, designed for students of technicaluniversities, should be based on direct operations performed by the student onreal devices. At the same time, at the later stages of didactic...
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Validation of result of STM probe fabrication
Open Research DataThe scanning tunneling microscope [1] is a powerful research tool that allows, among other things, to obtain images with atomic resolution. A serious limitation of the described microscope is its limited applicability relating to conductive and semiconductor materials and the reproducibility of measurements depending on the preparation of the measuring...
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Quasi-resonant DC-link voltage inverter with enhanced zero-voltage switching control
PublicationA new topology modification of the parallel quasi-resonant circuit for a dc-link voltage inverter enables regulation of the zero voltage dc-link subperiods and the dc-link voltage gradient settings. The proposed circuit is based on four MOSFET switches with free-wheeling diodes for controlled quasi-resonant recharging between L-C tank in order to assure inverter zero voltage switching (ZVS) conditions. Design optimization of the...
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Multiple output second-generation current conveyor utilizing high frequency output stage
PublicationIn this paper a multiple output second-generation current conveyor (MOCCII) is presented. The main advantage of the proposed general circuit architecture over a typical structure, well known in the literature, is the use of a high passband multiple output current mplifier block instead of cascaded current mirrors. It gives similar frequency responses for all the outputs of the current conveyor and also maintains simplicity of the...
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STANY NIEUSTALONE TOWARZYSZĄCE POMIAROWI IMPEDANCJI PĘTLI ZWARCIA W OBWODACH WYJŚCIOWYCH ZASILACZY BEZPRZERWOWYCH UPS
PublicationW pracy przedstawiono metodykę i wyniki pomiarów stanów nieustalonych w zasilaczu bezprzerwowym (UPS) typu on - line. Do rejestracji zdarzeń po stronie zasilania i na wyjściu UPS wykorzystano dwa przyrządy do pomiaru jakości energii elektrycznej zsynchronizowane czasowo. Rejestratory kompresują uzyskane dane pomiarowe, co może wprowadzać dodatkowe błędy pomiaru wielkości mierzonych – napięć i prądów. Dodatkowe rejestracje oscyloskopem...
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SEM micrographs of cavitation erosion-corrosion of aluminium alloy 2024 with anodic polarization
Open Research DataThe dataset contains Scanning Electron Micrographs of aluminium alloy 2024 samples made after cavitation erosion-corrosion exposure using a vibratory transducer (in accordance with ASTM G32). The experiment duration was 240 min, with cyclic cavitation exposure in on/off cycles 30s:30s. The electrolyte was 0.1 M KNO3 solution. Some samples were anodically...
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A 0.5-V bulk-driven voltage follower / DC level shifter and its application in class AB output stage
PublicationA simple realization of a 0.5-V bulk-driven voltage follower/DC level shifter, designed in a 0.18um CMOS technology is presented in the paper. The circuit is characterized by large input and output voltage swings, and a DC voltage gain close to unity. The DC voltage shift between input and output terminals can be regulated in a certain interval around zero, by means of biasing current sinks. An application of the proposed voltage...
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The behavioural model of graphene field-effect transistor
PublicationThe behavioural model of a graphene field-effect transistor (GFET) is proposed. In this approach the GFET element is treated as a “black box” with only external terminals available and without considering the physical phenomena directly. The presented circuit model was constructed to reflect steady-states characteristics taking also into account GFET capacitances. The authors’ model is defined by a relatively small number of equations...
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LOW COST MEASUREMENT MODULE FOR MATRIX OF AMPEROMETRIC GAS SENSOR
PublicationThis paper describes an amperometric sensor module for gas concentration measurement. A module can be used for many types of electrochemical gas sensors without major hardware changes. Device is based on AVR ATmega8 microcontroller. As signal processing circuit a specialized integrated circuit LMP9l000 configurable via I2C interface is used. The concept of a measuring system composed of several modules dedicated for a gas sensors...
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Nowa metoda obliczania rozpływu prądów zwarciowych w przewodach odgromowych linii wysokiego napięcia
PublicationReferat przedstawia nowatorską metodę obliczania wartości prądów płynących w przewodach odgromowych w czasie zwarć, pozwalającą na dobór przewodów odgromowych pod względem wytrzymałości cieplnej. Proponowana metoda charakteryzuje się większą dokładnością i większą uniwersalnością niż powszechnie stosowane metody, pozwalając tym samym na dobór przewodów odgromowych z mniejszym ryzykiem niepewności. Prezentowana metoda obliczeniowa...
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Stability Analysis of Shunt Active Power Filter with Predictive Closed-Loop Control of Supply Current
PublicationThis paper presents a shunt active power filter connected to the grid via an LCL coupling circuit with implemented closed‐loop control. The proposed control system allows selective harmonic currents compensation up to the 50th harmonic with the utilization of a model‐based predictive current controller. As the system is fully predictive, it provides high effectiveness of the harmonic reduction, which is proved by waveforms achieved...
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Verification and Benchmarking in MPA Coprocessor Design Process
PublicationThis paper presents verification and benchmarking required for the development of a coprocessor digital circuit for integer multiple-precision arithmetic (MPA). Its code is developed, with the use of very high speed integrated circuit hardware description language (VHDL), as an intellectual property core. Therefore, it can be used by a final user within their own computing system based on field-programmable gate arrays (FPGAs)....
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Low cost set-up for supercapacitors parameters evaluation
PublicationSupercapacitors are capable to store relatively high amount of energy comparing to its mass. Growing number of these devices applications requires development of new testing methods. Standard methods of evaluation of supercapacitor parameters, as cycling voltammetry, CV, galvanostatic cycling with potential limitation, GCPL, impedance measurements, require equipment of high cost...
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Rapid optimization of compact microwave passives using kriging surrogates and iterative correction
PublicationDesign 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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Errors in the analysis of series resonant inverter/converter assuming sinusoidal waveforms of voltage and current
PublicationIn this paper the theory and simulation results of the series resonant inverter / converter are presented. In this work the authors carried out a detailed comparative analysis of results obtained using the method of AC analysis in the steady state for the first harmonic with the results of computer simulation. The AC analysis under certain conditions can lead to errors disqualifying this method. In particular, these errors appear...
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Power and energy measurement problems in transmission line between Poland-Lithuania
PublicationThe paper discusses problem of power and energy metering in double circuit overhead transmission line. Considerations are based on example of transmission line connecting Polish substation Bis Elk and Lithuanian substation Alytus.
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Multi-mode vibronic interactions in the five lowest electronic states of the fluorobenzene radical cation
PublicationThe multi-mode vibronic interactions between the five lowest electronic states of the fluorobenzene radical cation are investigated theoretically, based on ab initio electronic structure data, and employing the linear vibronic coupling model. Low-energy conical intersections, and strong vibronic couplings are found to prevail within the set of X-A and B-C-D cationic states, while the interactions between these two sets of states...
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The influence of SVC on the progress of voltage collapse
PublicationThe article presents the simulation concerning the cooperation of SVC circuit with a generative set in time, when of power system reaches low values which may lead to the fall-out of generator from the synchronous operation.
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Analysis of noise properties of the optocoupler device
PublicationIn the paper the localization of a source of Random Telegraph Signal noise (RTS noise) in optocoupler devices type CNY 17 were defined. The equivalent noise circuit in low frequency noise for these type optocouplers was proposed.
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GaN Nanowire Array for Charge Transfer in Hybrid GaN/P3HT:PC71BM Photovoltaic Heterostructure Fabricated on Silicon
PublicationAbstract: We demonstrate that a GaN nanowire array can be used for efficient charge transfer between the organic photovoltaic layer and silicon in a Si/GaN/P3HT:PC71BM inverted hybrid heterostructure. The band alignment of such a material combination is favorable to facilitate exciton dissociation, carrier separation and electron transport into Si. The ordered nature of the GaN array helps to mitigate the intrinsic performance...
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Influence of excitons interaction with charge carriers on photovoltaic parameters in organic solar cells
PublicationWe report on theoretical analysis of excitons annihilation on charge carriers in organic solar cells. Numerical calculations based on transient one-dimensional drift-diffusion model have been carried out. An impact of three quantities (an annihilation rate constant, an exciton mobility and a recombination reduction factor) on current density and concentrations of charge carriers and excitons is investigated. Finally, we discuss...
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Bandwidth-size design trade-offs for compact spline-parameterised patch couplers by means of electromagnetic-driven multi-objective optimisation
PublicationBroad bandwidth and small size are the key performance figures for contemporary microwave couplers. These requirements are conflicting, i.e. improvement of one generally leads to degradation of the other assuming fixed topology of the circuit at hand. From a designer's perspective, the knowledge about available design trade-offs is indispensable as it permits for tailoring the circuit for particular applications as well as comparing...
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Objectivity in the non-Markovian spin-boson model
PublicationObjectivity constitutes one of the main features of the macroscopic classical world. An important aspect of the quantum-to-classical transition issue is to explain how such a property arises from the microscopic quantum theory. Recently, within the framework of open quantum systems, there has been proposed such a mechanism in terms of the so-called spectrum broadcast structures. These are multipartite quantum states of the system...
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Size Reduction of Microwave Couplers by EM-Driven Optimization
PublicationThis 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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Novel structure and EM-driven design of miniaturized microstrip rat-race coupler
PublicationIn this paper, a novel structure and design procedure of a miniaturized microstrip rat-race coupler (RRC) is described. Small size of the RRC is achieved by folding the transmission lines of the conventional circuit into its interior, as well as by implementation of the structure on three layers. The final size of the coupler realized for the operating frequency of 1 GHz is only 220 mm2, which gives over 95% footprint reduction...
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Single and Three -Phase PWM AC/AC Converters as Semiconductor Transformers
PublicationAC voltage transformation circuits contain pure or reactance PWM AC/AC converters. These circuits can be treated as AC/AC semiconductor transformers. This paper reviews single-phase and three-phase topologies: both non-isolated and isolated, single as well as two quadrant structure. Additionally, this paper present selected examples of their applications.
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Cost-Efficient Two-Level Modeling of Microwave Passives Using Feature-Based Surrogates and Domain Confinement
PublicationA variety of surrogate modelling techniques has been utilized in high-frequency design over the last two decades. Yet, the curse of dimensionality still poses a serious challenge in setting up re-liable design-ready surrogates of modern microwave components. The difficulty of the model-ing task is only aggravated by nonlinearity of circuit responses. Consequently, constructing a practically usable surrogate model, valid across...
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Rapid Design Tuning of Miniaturized Rat-Race Couplers Using Regression-Based Equivalent Network Surrogates
PublicationA simple technique for fast design tuning of compact rat-race couplers is presented. Our approach involves equivalent circuit representation, corrected by nonlinear functions of frequency with coefficients extracted through nonlinear regression. At the same time, the tuning process connects two levels of coupler representation: EM simulation of the entire circuit and re-optimization of the coupler building blocks (slow-wave cells...
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Model of the double-rotor induction motor in terms of electromagnetic differential
PublicationThe paper presents a concept, a construction, a circuit model and experimental results of the double-rotor induction motor. This type of a motor is to be implemented in the concept of the electromagnetic differential. At the same time it should fulfill the function of differential mechanism and the vehicle drive. One of the motor shafts is coupled to the direction changing mechanical transmission. The windings of the external rotor...
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An Implementation of a Compact Smart Resistive Sensor Based on a Microcontroller with an Internal ADC
PublicationIn the paper a new implementation of a compact smart resistive sensor based on a microcontroller with internal ADCs is proposed and analysed. The solution is based only on a (already existing in the system) microcontroller and a simple sensor interface circuit working as a voltage divider consisting of a reference resistor and the resistive sensor connected in parallel with an interference suppression capacitor. The measurement...
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Marek Wójcikowski dr hab. inż.
PeopleMarek Wójcikowski graduated in 1993 from the Department of Electronics at Gdansk University of Technology (GUT). In 2002 he obtained a doctoral degree in the field of electronics and in 2016 he obtained a habilitation at the Faculty of Electronics, Telecommunications and Informatics at GUT. From the beginning of his career he is associated with GUT: first as an assistant (years 1994-2002) and then as assistant professor (since...
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Implementation of Addition and Subtraction Operations in Multiple Precision Arithmetic
PublicationIn this paper, we present a digital circuit of arithmetic unit implementing addition and subtraction operations in multiple-precision arithmetic (MPA). This adder-subtractor unit is a part of MPA coprocessor supporting and offloading the central processing unit (CPU) in computations requiring precision higher than 32/64 bits. Although addition and subtraction operations of two n-digit numbers require O(n) operations, the efficient...
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Dielectric Properties of BiNbO<sub>4</sub>-Based Ceramic-Polymer Composites with 0-3 Connectivity
PublicationIn the present study two-phase BiNbO4//PVDF composites with 0-3 connectivity were studied by impedance spectroscopy within the frequency range Δν=100Hz-1MHz at room temperature. Polyvinylidene fluoride (PVDF) acted as a matrix whereas bismuth niobate (BiNbO4) powder acted as a dispersed phase. The volume fraction of the ceramic phase was cV=2, 4, 6, 8, 10, 16 and 20vol%. Analysis of the impedance data registered for composites...
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Optimization-based antenna miniaturization using adaptively-adjusted penalty factors
PublicationThe continuing trend for miniaturization of electronic devices necessitates size reduction of the comprising components and circuitry. Specifically, integrated circuit-antenna modules therein require compact radiators in applications such as 5G communications, implantable and on-body devices, or internet of things (IoT). The conflict between the demands for compact size and elec-trical and field performance can be mitigated by...
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Optimized Hydrodynamic Vortex Separator
PublicationThe invention discloses an optimized hydrodynamic vortex separator which comprises an outer cylinder (1), an inner cylinder (2), a sludge hopper (3), an inlet (4), an outlet (5) and a conical structure (7), wherein the outer cylinder (1) is the boundary of the outer wall of the separator; wherein the inner cylinder (2) is arranged in an inner cavity of the outer cylinder (1); the sludge hopper (3)is taken as the bottom of the...
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Frequency-Variant Double-Zero Single-Pole Reactive Coupling Networks for Coupled-Resonator Microwave Bandpass Filters
PublicationIn this work, a family of frequency-variant reactive coupling (FVRC) networks is introduced and discussed as new building blocks for the synthesis of coupled-resonator bandpass filters with real or complex transmission zeros (TZs). The FVRC is a type of nonideal frequency-dependent inverter that has nonzero elements on the diagonal of the impedance matrix, along with a nonlinear frequency-variation profile of its transimpedance...
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Knowledge-Based Expedited Parameter Tuning of Microwave Passives by Means of Design Requirement Management and Variable-Resolution EM Simulations
PublicationThe importance of numerical optimization techniques has been continually growing in the design of microwave components over the recent years. Although reasonable initial designs can be obtained using circuit theory tools, precise parameter tuning is still necessary to account for effects such as electromagnetic (EM) cross coupling or radiation losses. EM-driven design closure is most often realized using gradient-based procedures,...
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Improved-Efficacy Optimization of Compact Microwave Passives by Means of Frequency-Related Regularization
PublicationElectromagnetic (EM)-driven optimization is an important part of microwave design, especially for miniaturized components where the cross-coupling effects in tightly arranged layouts make traditional (e.g., equivalent network) representations grossly inaccurate. Efficient parameter tuning requires reasonably good initial designs, which are difficult to be rendered for newly developed structures or when re-design for different operating...
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Computationally efficient two-objective optimization of compact microwave couplers through corrected domain patching
PublicationFinding 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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Computationally-Efficient Statistical Design and Yield Optimization of Resonator-Based Notch Filters Using Feature-Based Surrogates
PublicationModern microwave devices are designed to fulfill stringent requirements pertaining to electrical performance, which requires, among others, a meticulous tuning of their geometry parameters. When moving up in frequency, physical dimensions of passive microwave circuits become smaller, making the system performance increasingly susceptible to manufacturing tolerances. In particular, inherent inaccuracy of fabrication processes affect...