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Wyniki wyszukiwania dla: NUMERICAL MODELING DOUFOURE AND SORRET EFFECT INCLINED MHD NONLINEAR RADIATIONS MICRO MOTILE ORGANISMS NANOFLUID MULTI SLIP CONDITIONS
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Effect of multi-walled carbon nanotubes properties on the photocatalytic activity of bismuth-based composites synthesised via an imidazolium ionic liquid
PublikacjaThe use of various types of multi-walled carbon nanotubes in the synthesis of bismuth oxybromide semiconductors via imidazolium ionic liquid was studied in detail. The effect of the MWCNT shape, specific surface area, and various diameters on the morphology, surface properties and photoactivity of the Bi-based composites has been investigated for the first time. So far, the literature has only shown the enhancement of photocatalytic...
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Numerical study of turbulent flow and heat transfer of nanofluids in pipes
PublikacjaIn this work, Nusselt number and friction factor are calculated numerically for turbulent pipe flow (6 000 < Re < 12 000) with constant heat flux boundary condition using nanofluids. The nanofluid is modelled with the single-phase approach and the simulation results are compared with experimental data of Vajjha et al. [1]. Ethylene glycol and water, 60:40 EG/W mass ratio, as base fluid and SiO2 nanoparticles are used as nanofluid...
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Effectiveness of a mathematical model in simulating nonlinear mechanical behaviour of a seismic isolation system made of polymeric bearings
PublikacjaThe present study was focused on determining the effectives of a nonlinear mathematical model in simulating complex mechanical behaviour of a seismic isolation system made of Polymeric Bearings. The proposed mathematical model defines the lateral force as a nonlinear function of the shear displacement and the deformation velocity. The effectiveness of the proposed mathematical model was verified by comparing the seismic response...
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Effect of operating conditions on N 2 O production in an anammox sequencing batch reactor containing granular sludge
PublikacjaNitrous oxide (N2O) is one of the gases with the greatest impact in the atmosphere due to its persistence and significant contribution to the greenhouse effect. This study provides an insight into the dynamics of N2O production in wastewater nitrogen removal systems. A 10 L sequencing batch reactor containing enriched anammox biomass was subjected to different operational conditions, i.e., temperature, feed time, NO2 /NH4 þ ratio...
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Modeling of hazards, consequences and risk for safety assessment of ships in damaged conditions in operation
PublikacjaPraca dotyczy problematyki związanej z modelowaniem zagrożeń, konsekwencji i ryzyka, w metodzie oceny bezpieczeństwa statków w stanie uszkodzonym. Metoda oparta jest na podejściu zorientowanym na ocenę zachowania się statku i ocenę ryzyka wypadku. Kolejne moduły metody dotyczą identyfikacji zagrożeń i scenariuszy wypadków oraz oceny i kontroli ryzyka. Ocenę ryzyka można przeprowadzić przy zastosowaniu elementów metodyki Przypadku...
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Time Domain Modeling of Propeller Forces due to Ventilation in Static and Dynamic Conditions
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Electrochemical degradation of textile dyes in a flow reactor: effect of operating conditions and dyes chemical structure
PublikacjaIn this study, electrochemical oxidation of five azo dyestuffs (Yellow D-5GN, Red D-B8, Ruby F-2B, Blue D-5RN, Black DN), that are widely used in the textile industry, was investigated in a flow reactor. BDD electrode with a high boron doping level (C/B = 10 000) was prepared and used. Two configurations of reactor were considered, i.e., one with the undivided cell, and the other with the cell divided by anodic and cathodic compartments....
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The effect of unfavourable process conditions on the water desalination by membrane distillation
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Effect of boundary conditions in shear testers on properties of bulk solids.
PublikacjaPrzedstawiono wpływ warunków brzegowych w dwóch różnych aparatach ścinania na wielkość odkształceń i naprężeń. Obliczenia wykonano przy zastosowaniu metody elementów skończonych i mikropolarnego prawa hipoplastycznego.
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Investigation on the edge forces in ball end milling of inclined surfaces
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Nonlinear properties of the Gotland Deep – Baltic Sea
PublikacjaThe properties of the nonlinear phenomenon in water, including sea water, have been well known for many decades. The feature of the non homogeneous distribution of the speed of sound along the depth of the sea is very interesting from the physical and technical point of view. It is important especially in the observation of underwater area by means of acoustical method ( Grelowska et al ., 2013; 2014). The observation of the underwater...
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Performance of the PVT solar collector operated with water-Al2O3 nanofluid
PublikacjaAn experimental investigation of the hybrid module photovoltaic panel -solar collector (PVT) cooled by water-Al2O3 nanofluids has been conducted. The weight fractions of the nanoparticles were 1% and 3%. Thermal efficiency, power efficiency and overall efficiency have been determined for artificial source of light and sunlight. No noticeable effect of the nanoparticle concentration on the overall efficiency of the PVT module has...
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PERFORMANCE OF THE PVT SOLAR COLLECTOR OPERATED WITH WATER –AL2O3 NANOFLUID
PublikacjaAn experimental investigation of the hybrid module photovoltaic panel -solar collector (PVT) cooled by water-Al2O3 nanofluids has been conducted. The weight fractions of the nanoparticles were 1% and 3%. Thermal efficiency, power efficiency and overall efficiency have been determined for artificial source of light and sunlight. No noticeable effect of the nanoparticle concentration on the overall efficiency of the PVT module has...
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Numerical and experimental propeller noise investigations
PublikacjaThe standard propeller has been investigated in model scale, using medium size cavitation tunnel. The hydroacoustic characteristics of propellers under different loading conditions have been investigated. Additionally the presented experimental results have been used for the verification of applied numerical approach. During both numerical and experimental analyses non-uniform inflow propeller’s conditions have been adapted. Good...
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Modeling in Machine Design
Kursy OnlineThe course is meant to show the students how to build calculation models in machine design
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Numerical modeling of exciton impact in two crystalographic phases of the organo-lead halide perovskite (CH3NH3PbI3) solar cell
PublikacjaTo improve the power conversion efficiency of solar cells based on organo–lead halide perovskites, a detailed understanding of the device physics is fundamental. Here, a computational analysis of excitons impact is reported for these types of photocell. Numerical calculations based on the model, which take into account electronic charge carriers (electrons and holes), excitons and ions, have been carried out. The role of excitons...
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Elastoplastic nonlinear FEM analysis of FGM shells of Cosserat type
PublikacjaThe paper is a continuation of [1] where the formulation of the elastic constitutive law for functionally graded materials (FGM) on the grounds of nonlinear 6-parameter shell theory with the 6th parameter (the drilling degree of freedom) was presented. Here the formulation is extended to the elasto-plastic range. The material law is based on Cosserat plasticity and employs the well-known Tamura-Tomota-Ozawa (TTO) [2] mixture...
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Method of lines for nonlinear first order partial functional differential equations.
PublikacjaClassical solutions of initial problems for nonlinear functional differential equations of Hamilton--Jacobi type are approximated by solutions of associated differential difference systems. A method of quasilinearization is adopted. Sufficient conditions for the convergence of the method of lines and error estimates for approximate solutions are given. Nonlinear estimates of the Perron type with respect to functional variables...
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Knowledge-based performance-driven modeling of antenna structures
PublikacjaThe importance of surrogate modeling techniques in the design of modern antenna systems has been continuously growing over the recent years. This phenomenon is a matter of practical necessity rather than simply a fashion. On the one hand, antenna design procedures rely on full-wave electromagnetic (EM) simulation tools. On the other hand, the computational costs incurred by repetitive EM analyses involved in solving common tasks...
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Grand Challenges on the Theory of Modeling and Simulation
PublikacjaModeling & Simulation (M&S) is used in many different fields and has made many significant contributions. As a field in its own right, there have been many advances in methodologies and technologies. In 2002 a workshop was held in Dagstuhl, Germany, to reflect on the grand challenges facing M&S. Ten years on, a series of M& S Grand Challenge activities are marking a decade of progress and are providing an opportunity to reflect...
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A multi‑criteria approach to investigate spatial distribution,sources, and the potential toxicological effect of polycyclic aromatic hydrocarbons (PAHs) in sediments of urban retention tanks
PublikacjaBottom sediments deposited in retention tanks (RTs) located on two urban streams (Oliwski and Strzyza) in the central part of Gdansk (Poland) were analysed for polycyclic aromatic hydrocarbons’ (PAHs) content. PAHs were extracted from samples with methylene chloride, then the extracts were subjected to clean-up applying the solid phase extraction (SPE) method. Quantitative and qualitative determination of 16 PAHs was performed...
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Effect of grain crushing on shear localization in granular bodies within micro-polar hypoplasticity
PublikacjaW artykule przedstawiono efekt miażdżenia ziaren na zachowanie się materiału granulowanego podczas ścinania nieskończenie długiej warstwy piasku. Obliczenia wykonano przy pomocy mikropolarnego prawa hipoplastycznego rozszerzonego o efekt miażdżenia ziaren w oparciu o teorię mechaniki zniszczenia. Zbadano wpływ wstępnego zagęszczenia i poziomu naprężeń na strefy lokalizacji.
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Closed Form Constraint Equations Used to Express Frictionless Slip of Multibody Systems Attached to Finite Elements—Application to a Contact between a Double Pendulum and a Beam
PublikacjaThis paper focuses on the numerical modeling of the dynamics of mechanical systems. Robots that can inspect high-voltage lines inspired this research. Their control systems must anticipate potential grab positions appropriately. We intend to formulate equations dedicated to the numerical description of the robot/cable contact. The investigated problem is not straightforward, since parts of the modeled systems are numerically inhomogeneous....
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Journal of Chemical Information and Modeling
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Studying the Effect of Working Conditions on WEDM Machining Performance of Super Alloy Inconel 617
PublikacjaWire electrical discharge machining (WEDM) has been for many years a precise and efficient non-conventional manufacturing solution in various industrial applications, mostly involving the use of hard-to machine materials like, among other, the Inconel super alloys. The focus of the present study is on exploring the effect of selected control parameters, including pulse duration, pulse-off time and the dielectric flow pressure on...
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Recent Advances in Performance-Driven Surrogate Modeling of High-Frequency Structures
PublikacjaDesign of high‐frequency structures, including microwave and antenna components, heavily relies on full‐wave electromagnetic (EM) simulation models. Their reliability comes at a price of a considerable computational cost. This may lead to practical issues whenever numerous EM analyses are to be executed, e.g., in the case of parametric optimization. The difficulties entailed by massive simulations may be mitigated by the use of...
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The equations for interactions of polarization modes in optical fibres including the kerr effect
PublikacjaWe have derived coupled nonlinear Schro¨ dinger equations (CNLSE) for arbitrary polarized light propagation in a single-mode fibre employing electromagnetic field complete description. We used a basis of transverse eigenmodes with appropriate projecting; hence, the nonlinear constants depend on the waveguide geometry. Accounting for a weak nonlinearity, which is connected to the Kerr effect, we have given explicit expressions for...
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Nonlinear electrical properties of glass-ceramics nanocomposites containing ferroelectric nanocrystallites of Bi2VO5.5
PublikacjaNonlinear A.C. impedance measurements were conducted in the 50BiV-50SrBAlO nanocomposite as a function of frequency, temperature and A.C. voltage. This material is ferroelectric below temperature of 730 K, and above 730 K is a good ion-conductor. For this nanocomposite a low A.C. voltage of 1 V rms is enough to observe high nonlinearities. The origin of these nonlinear effects depends on the temperature and frequency. In the high...
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Effect of Na doping on photoluminescence and laser stimulated nonlinear optical features of ZnO nanostructures
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The effect of nonlinear restraint on torsional buckling and post-buckling behaviour of a thin-walled column
PublikacjaW pracy rozważa się wyboczenie skrętne i zachowanie pokrytyczne osiowo ściskanego swobodnie podpartego pręta cienkosciennego o przekroju otwartym ze sprężytą nieliniową podporą w środku rozpietości. Rozwiązanie problemu wyznaczono za pomocą metody małego parametru. W przykładzie numerycznym wyznaczono siłę krytyczną i ścieżkę początkowego zachowania pokrytycznego dwuteowego pręta z podporą sprężystą o charakterystyce składającej...
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Combined numerical and experimental approach to determine numerical model of abdominal scaffold
PublikacjaA proper junction of the prosthesis and the abdominal wall is important in successful hernia repair. The number of tacks should be balanced to assure appropriate mesh fixation and not to induce post-operative pain. Numerical simulations help to find this balance. The study is aimed at creating a proper numerical model of a knitted surgical mesh subjected to boundary conditions and load occurring in the abdominal cavity. Continuous,...
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The nonlinear effects of sound in a liquid with relaxation losses
PublikacjaThe nonlinear effects of sound in electrolyte with a chemical reaction are examined. The dynamic equations that govern non-wave modes in the field of intense sound are derived, and acoustic forces of vortex, entropy, and relaxation modes are determined in the cases of low-frequency sound and high-frequency sound. The difference in the nonlinear effects of sound in electrolyte and in a gas with excited vibrational degrees of molecules,...
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Numerical simulation of hardening of concrete plate
PublikacjaThe paper presents a theoretical formulation of concrete curing in order to predict temperature evolution and strength development. The model of heat flow is based on a well-known Fourier equation. The numerical solution is implemented by means of the Finite Difference Method. In order to verify the model, the in situ temperature measurements at the top plate of a road bridge were carried out. A high agreement between numerical...
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Antenna Modeling Using Variable-Fidelity EM Simulations and Constrained Co-Kriging
PublikacjaUtilization of fast surrogate models has become a viable alternative to direct handling of fullwave electromagnetic (EM) simulations in EM-driven design. Their purpose is to alleviate the difficulties related to high computational cost of multiple simulations required by the common numerical procedures such as parametric optimization or uncertainty quantification. Yet, conventional data-driven (or approximation) modeling techniques...
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Hydrodynamic reanalysis of ice conditions in the Baltic Sea using the PM3D model
Dane BadawczeThe dataset contains the results of numerical modeling of sea ice in the Baltic Sea since 1998. A long-term reanalysis was performed using the three-dimensional hydrodynamic model PM3D (Kowalewski and Kowalewska-Kalkowska, 2017), a new version of the M3D model (Kowalewski, 1997). A numerical dynamic-thermodynamic model of sea ice (Herman et al. 2011)...
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Ship Dynamic Positioning Based on Nonlinear Model Predictive Control
PublikacjaThe presented work explores the simulation test results of using nonlinear model predictive control algorithm for ship dynamic positioning. In the optimization task, a goal function with a penalty was proposed with a variable prediction step. The results of the proposed control algorithm were compared with backstepping and PID. The effect of estimation accuracy on the control quality with the implemented algorithms was investigated....
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Effect of crystallization process at cryogenic conditions on the functional properties of the SUPERSTON alloy used in production the ship's propellers
PublikacjaThe purpose of this paper is to show results of laser treatment at cryogenic conditions of the SUPERSTON alloy used for ship's propellers. That modification process ought to bring beneficial changes of microstructure and residual stresses in the surface layer. During the laser remelting at cryogenic conditions the microstructure changes significantly. This is related to synergistic effects of the solidification rate, phase transformations...
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A Nonlinear Model of a Mesh Shell
PublikacjaFor a certain class of elastic lattice shells experiencing finite deformations, a continual model using the equations of the so-called six-parameter shell theory has been proposed. Within this model, the kinematics of the shell is described using six kinematically independent scalar degrees of freedom — the field of displacements and turns, as in the case of the Cosserat continuum, which gives reason to call the model under consideration...
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Design analysis of Tesla micro-turbine operating on a low-boiling medium
PublikacjaThis paper presents results of the design analysis of a Tesla bladeless turbine intended for a co-generating micro-power plantof heat capacity 20 kW, which operates in an organic Rankine cycle on a low-boiling medium. Numerical calculations of flowin several Tesla turbine models were performed for a range of design parameters. Results of investigations exhibit interestingfeatures in the distribution of flow parameters within the...
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Numerical and physical modeling of water flow over the ogee weir of the new Niedów barrage
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Free surface flow modeling in numerical estimation of flood risk zones: a case study
PublikacjaNa przykładzie doliny Wisły w Warszawie przedstawiono metodę wyznaczenia stref zagrożenia powodziowego. Symulowana numerycznie powódź wywołana została potencjalnym przerwaniem obwałowania rzeki w okolicach Saskiej Kępy. Do obliczeń zastosowano opracowany w Katedrze Hydrotechniki Wydziału Inżynierii Lądowej i Środowiska Politechniki Gdańskiej model dwuwymiarowego, płaskiego przepływu wody ze swobodną powierzchnią.
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Numerical modeling of cross-flow heat exchanger for air-conditioning purposes in preliminary study.
PublikacjaPraca przedstawia wyniki obliczeń numerycznych krzyżowego płytowo-rurowego wymiennika ciepła przeznaczonego do celów klimatyzacyjnych w początkowym etapie jego projektowania.
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Computing internodal conductivities in numerical modeling of two dimensional unsaturated flow on rectangular grid
PublikacjaW artykule porównano rozwiązania numeryczne dwuwymiarowego równania przepływu nienasyconego z użyciem różnych metod uśredniania współczynnika przewodności hydraulicznej między sąsiednimiwęzłami. Uwzględniono średnia arytmetyczną, geometryczną, "pod prad" oraz całkową, a także niedawno zaproponowany sposób uśredniania oparty na analizie przepływu ustalonego. Ten ostatni sposób okazałsię najbardziej uniwersalny, gdyż umożliwiał otrzymanie...
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Numerical analysis of mechanical properties of an infill structure used in 3D printings
PublikacjaThe paper presents results of a numerical analysis focused on an identification of mechanical properties of an element created by using Fused Deposition Modelling additive manufacturing technique (FDM). There is presented a description of technology of the 3D printing, numerical model created by using the finite element method (FEM), as well as some problems referred to estimation of the mechanical properties of the printout. The...
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Systems of Nonlinear Fractional Differential Equations
PublikacjaUsing the iterative method, this paper investigates the existence of a unique solution to systems of nonlinear fractional differential equations, which involve the right-handed Riemann-Liouville fractional derivatives D(T)(q)x and D(T)(q)y. Systems of linear fractional differential equations are also discussed. Two examples are added to illustrate the results.
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Effect of Porosity on the Thermo-Mechanical Behavior of Friction-Stir-Welded Spark-Plasma-Sintered Aluminum Matrix Composites with Bimodal Micro- and Nano-Sized Reinforcing Al2O3 Particles
PublikacjaThe thermo-mechanical behavior of nanosized Al2O3 particles reinforcing aluminum was analyzed in the present paper. The material was prepared by spark plasma sintering and friction stir welding. The thermal stresses affecting the composite behavior during welding were modeled through COMSOL MultiPhysics, and the results were validated by the analyses of the composites’ mechanical properties. The spark-plasma-sintered materials...
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Performance-Driven Surrogate Modeling of High-Frequency Structures
PublikacjaThe development of modern high-frequency structures, including microwave and antenna components, heavily relies on full-wave electromagnetic (EM) simulation models. Notwithstanding, EM-driven design entails considerable computational expenses. This is especially troublesome when solving tasks that require massive EM analyzes, parametric optimization and uncertainty quantification be-ing representative examples. The employment of...
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Very high altitude micro air vehicle deployment method
PublikacjaThe paper presents the original work and method for high altitude micro air vehicle deployment. The method is based on the scientific ballooning, and adapted for stratospheric flight of commercial off-the-shelf micro air vehicle in flying wing configuration. The High Altitude Micro Air Vehicle, built for this research, was deployed during a test experiment at the lower level of the stratosphere. The results of the experiment and...
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Textile reinforced concrete members subjected to tension, bending, and in-plane loads: Experimental study and numerical analyses
PublikacjaTextile reinforced concrete has raised increasing research interest during the last years, mainly due to its potential to be used for freeform shell structures involving complex load situations. Yet, most experimental work has focused on test setups with primarily uniaxial loading. In the current work, such setups are complemented with a novel test setup of deep beams, including in-plane bending and shear. Further, nonlinear finite...
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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...