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Effect of waviness and roughness components on transverse profiles of turned surfaces
PublikacjaThis paper presents the authors method of simultaneous analysis of roughness and waviness irregularity components, with the aim of better defining the key qualities and characteristics.Periodical surface machining traces may be analyzed spectrally, with the irregularity's peaks and troughs being used to define the wave's amplitude.In this work the standard composition for filtering waviness and roughness components of a surface...
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Deep Eutectic Solvents and Their Uses for Air Purification
PublikacjaChemical compounds released into the air by the activities of industrial plants and emitted from many other sources, including in households (paints, waxes, cosmetics, disinfectants, plastic (PVC) flooring), may affect the environment and human health. Thus, air purification is an important issue in the context of caring for the condition of the environment. Deep eutectic solvents (DESs) as liquids with environmentally friendly...
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Numerical Study of the Impinging Jets Formed by an Injector with Different Nozzle Diameters
PublikacjaThe collision of two or more liquid jets may provide considerable atomisation and efficient mixing of injected substances at the same time. This phenomenon is used, among others, in rocket engines, where the fuel and oxidiser are introduced separately and almost immediately mixed through self-impingement. Depending on the injection and operating conditions, diverse configurations of impinging jets are used, such as doublets,...
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Open extensive IoT research and measurement infrastructure for remote collection and automatic analysis of environmental data.
PublikacjaInternet of Things devices that send small amounts of data do not need high bit rates as it is the range that is more crucial for them. The use of popular, unlicensed 2.4 GHz and 5 GHz bands is fairly legally enforced (transmission power above power limits cannot be increased). In addition, waves of this length are very diffiult to propagate under field conditions (e.g. in urban areas). The market response to these needs are the...
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Stationary underwater channel experiment: Acoustic measurements and characteristics in the Bornholm area for model validations
PublikacjaThe underwater acoustical channel is time-variant, and even on small time scales there is often existing no ‘acoustical frozen ocean’. Popular is the use of WSSUS-channel transmission modeling (Wide-Sense Stationary Uncorrelated Scattering) for the stochastic description of bandpass signals in GSM mobile phones with moving participants; since this results in a halved number of model parameters. For underwater sound applications...
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TINKTEP: A fully self-consistent, mutually polarizable QM/MM approach based on the AMOEBA force field
PublikacjaWe present a novel quantum mechanical/molecular mechanics (QM/MM) approach in which a quantum subsystem is coupled to a classical subsystem described by the AMOEBA polarizable force field. Our approach permits mutual polarization between the QM and MM subsystems, effected through multipolar electrostatics. Self-consistency is achieved for both the QM and MM subsystems through a total energy minimization scheme. We provide an expression...
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Comparative analysis of the flow control over a circular cylinder with detached flexible and rigid splitter plates
PublikacjaA comparative study is performed on a circular cylinder with both flexible and rigid splitter plates (SPs). This study has the novelty of using single and dual detached SPs located downstream of the cylinder. The dimensionless gap distance between the first splitter plate and the cylinder as well as the distance between the SPs are varied. The strain of flexible SPs can be used for energy harvesting from the flow. Therefore, a...
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Normalized Partial Scattering Cross Section for Performance Evaluation of Low-Observability Scattering Structures
PublikacjaThe development of diffusion metasurfaces created new opportunities to elevate the stealthiness of combat aircraft. Despite the potential significance of metasurfaces, their rigorous design methodologies are still lacking, especially in the context of meticulous control over the scattering of electromagnetic (EM) waves through geometry parameter tuning. Another practical issue is insufficiency of the existing performance metrics,...
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ENERGY ANALYSIS OF THE PROPULSION SHAFT FATIGUE PROCESS IN A ROTATING MECHANICAL SYSTEM PART II IDENTIFICATION STUDIES – DEVELOPING THE FATIGUE DURABILITY MODEL OF A DRIVE SHAFT
PublikacjaThe article presents a continuation of research carried out concerning identification of energy consequences of mechanical fatigue within a propeller shaft in a rotating mechanical system, while working under conditions of the loss of the required alignment of shaft lines. Experimental research was carried out on a physical model reflecting a full-sized real object: i.e., the propulsion system of the ship. It is proven, by means...
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Directed electromagnetic pulse dynamics: projecting operators method
PublikacjaIn this article, we consider a one-dimensional model of electromagnetic pulse propagation in isotropic media, takinginto account a nonlinearity of the third order. We introduce a method for Maxwell's equation transformation on thebasis of a complete set of projecting operators. The operators correspond to wave dispersion branches including thedirection of propagation. As the simplest result of applying the method, we derive a system...
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Velocity measurement using the fdoa method in ground-based radio navigation system
PublikacjaVelocity is one of the main navigation parameters of the moving objects. However some systems of position estimation using radio wave measurements cannot provide velocity data due to limitation of their performance. In this paper a velocity measurement method for DS-CDMA radio navigation system is proposed, which doesn’t require full synchronization of reference stations carrier frequencies. The article presents basics of FDOA...
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Ultrawideband transmission in physical channels: a broadband interference view
PublikacjaThe superposition of multipath components (MPC) of an emitted wave, formed by reflections from limiting surfaces and obstacles in the propagation area, strongly affects communication signals. In the case of modern wideband systems, the effect should be seen as a broadband counterpart of classical interference which is the cause of fading in narrowband systems. This paper shows that in wideband communications, the time- and frequency-domain...
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A robust design of a numerically demanding compact rat-race coupler
PublikacjaA fast and accurate design procedure of a computationally expensive microwave circuit has been presented step-by-step and experimentally validated on the basis of a compact rat-race coupler (RRC) comprising slow-wave resonant structures (SWRSs). The final compact RRC solution has been obtained by means of a sequential optimization scheme exploiting the implicit space mapping (ISM) algorithm. A well-suited surrogate optimization...
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Calculation of electron scattering lengths on Ar, Kr, Xe, Rn and Og atoms
PublikacjaFocusing on the noble gases, we calculate the scattering potential using the Dirac-Coulomb Hamiltonian supplemented with a model polarization potential. We determine the scattering lengths using two methods, namely phase shifts for very small scattering energies and the shape of the wave function for zero scattering energy. We compare our theoretical electron scattering length results on Ar, Kr and Xe atoms with existing experimental...
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On the convergence of a nonlinear finite-difference discretization of the generalized Burgers–Fisher equation
PublikacjaIn this note, we establish analytically the convergence of a nonlinear finite-difference discretization of the generalized Burgers-Fisher equation. The existence and uniqueness of positive, bounded and monotone solutions for this scheme was recently established in [J. Diff. Eq. Appl. 19, 1907{1920 (2014)]. In the present work, we prove additionally that the method is convergent of order one in time, and of order two in space. Some...
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Displacement Sensors Based on the Phase of the Reflection Coefficient of a Split Ring Resonator Loaded Transmission Line
Publikacja— In this paper, novel displacement sensors using a microstrip loaded with a pair of split ring resonators (SRRs) are proposed. It is shown that the phase of the reflection coefficient from the loading SRRs can be used for displacement sensing. The paper also proposes a differential version of the sensor that benefits from a higher sensitivity and reference zero, which is useful for alignment purposes. It is further shown that...
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Formulation of Time-Fractional Electrodynamics Based on Riemann-Silberstein Vector
PublikacjaIn this paper, the formulation of time-fractional (TF) electrodynamics is derived based on the Riemann-Silberstein (RS) vector. With the use of this vector and fractional-order derivatives, one can write TF Maxwell’s equations in a compact form, which allows for modelling of energy dissipation and dynamics of electromagnetic systems with memory. Therefore, we formulate TF Maxwell’s equations using the RS vector and analyse their...
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Extending the Frequency Limit of Microstrip-Coupled CSRR Using Asymmetry
PublikacjaAbstract— This article explains the frequency limitation in designing microstrip circuits based on a complementary split-ring resonator (CSRR) and reports a novel technique for increasing its operating frequency, which makes the CSRR suitable for high-frequency applications. This study helps in synthesizing the dimensions of symmetric CSRR (SCSRR) and asymmetric CSRR (ACSRR) circuits, which shows the applicability of the proposed...
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Recent advances in high-frequency modeling by means of domain confinement and nested kriging
PublikacjaDevelopment of modern high-frequency components and circuits is heavily based on full-wave electromagnetic (EM) simulation tools. Some phenomena, although important from the point of view of the system performance, e.g., EM cross-coupling effects, feed radiation in antenna arrays, substrate anisotropy, cannot be adequately accounted for using simpler means such as equivalent network representations. Consequently, the involvement...
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Non-linear FEM analysis of pounding-involved response of buildings under non-uniform earthquake excitation
PublikacjaThe aim of the paper is to show the results of the study investigating the influence of non-uniform earthquake excitation, due to spatial seismic effects connected with the propagation of seismic wave, on the pounding-involved response of two buildings. The three-dimensional non-linear FEM analysis has been conducted using the detailed models of colliding structures. Acceleration records for different structural supports have been...
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Approximate Cramér–Rao bound on Doppler error in correlation-processing relatively narrowband noise radar
PublikacjaThe paper studies limitations on accuracy of Doppler estimation in continuous-wave noise radar with correlation processing. Second order properties of output of the correlation receiver are evaluated and an approximate Cram´er-Rao bound on errors of Doppler measurement is derived. The accuracy of Doppler measurements is found to be affected by the following factors: power spectral density of noise signal, frequency response of the...
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Monosubstituted hydrazone β-cyclodextrin derivatives for pH-sensitive complex formation with aromatic drugs
PublikacjaA new and convenient synthetic pathway was developed to produce monosubstituted cyclodextrins with high yields. Each of the β-cyclodextrin derivatives described in this work has an aromatic substituent connected with cyclodextrin core by a pH-sensitive hydrazone linker and a carbon chain. Carbon chains differ in lengths having one or three carbon atoms. The correlation between water solubility and linker length was determined using...
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Rapid Design Tuning of Miniaturized Rat-Race Couplers Using Regression-Based Equivalent Network Surrogates
PublikacjaA 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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Cost-efficient simulation-driven design of compact impedance matching transformers
PublikacjaIn this paper, an algorithmic framework for cost-efficient design optimization of miniaturized impedance matching transformers has been presented. Our approach exploits a bottom-up design that involves translating the overall design specifications for the circuit at hand to its elementary building blocks (here, compact microstrip resonant cells, CMRCs), as well as fast surrogate-assisted optimization of the cells followed by simulation-based...
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Digital microcontroller for sonar waveform generator
PublikacjaGenerating sounding signals is essential for the operation of active sonar. The system should be highly reliable. This can be achieved through architecture, communication between the devices, and a well-designed and self–testing software. The system presented in the article is responsible for the generation of hydroacoustic sounding signals, and ensures proper interaction between power amplifiers and power supplies. Thanks to its...
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Extended phase diagram of RNiC2 family: Linear scaling of the Peierls temperature
PublikacjaPhysical properties for the late-lanthanide-based RNiC2 (R = Dy, Ho, Er, and Tm) ternary compounds are reported. All the compounds show antiferromagnetic ground state with the Néel temperature ranging from 3.4 K for HoNiC2 to 8.5 K for ErNiC2. The results of the transport and galvanomagnetic properties confirm a charge density wave state at and above room temperature with transition temperatures TCDW = 284, 335, 366, and 394 K for...
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Earthquake-induced pounding between superstructure segments of isolated bridge
PublikacjaThe use of seismic isolation in bridges is considered as one of the most promising advanced technologies to enhance the structural safety during earthquakes. However, the method results in larger displacements of superstructure segments increasing the probability of pounding between them. Reports after severe ground motions show that the earthquake-induced structural pounding may lead to significant damage in isolated bridges....
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One-Dimensional Modeling of Flows in Open Channels
PublikacjaIn this chapter, modeling of the unsteady open channel flow using one-dimensional approach is considered. As this question belongs to the well-known and standard problems of open channel hydraulic engineering, comprehensively presented and described in many books and publications, our attention is focused on some selected aspects only. As far as the numerical solution of the governing equations is considered, one can find out that...
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On Design Optimization of Miniaturized Microscrip Dual-Band Rat-Race Coupler with Enhanced Bandwidth
PublikacjaIn the paper, a novel topology of a miniaturized wideband dual-band rat-race coupler has been presented. Small size of the circuit has been obtained by meandering transmission lines of the conventional circuit. At the same time, the number of independent geometry parameters has been increased in order to secure sufficient circuit flexibility in the context of its design optimization for dual-band operation. Optimum dimensions of...
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Efficient analysis of structures with rotatable elements using model order reduction
PublikacjaThis paper presents a novel full-wave technique which allows for a fast 3D finite element analysis of waveguide structures containing rotatable tuning elements of arbitrary shapes. Rotation of these elements changes the resonant frequencies of the structure, which can be used in the tuning process to obtain the S-characteristics desired for the device. For fast commutations of the response as the tuning elements are rotated, the...
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Recent and Emerging Applications of Graphene-based metamaterials in Electromagnetics
PublikacjaSurface Plasmon Polaritons (SPPs) operating in mid-infrared up to terahertz (THz) frequencies have been traditionally manufactured on expensive metals such as gold, silver, etc. However, such metals have poor surface confinement that limits the optical applications of SPPs. The invention of graphene is a breakthrough in plasmon-based devices in terms of design, fabrication and applications, thanks to its plasmonic wave distribution,...
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Imaging polarimeter with high-accuracy measuring principles in crystal optics
PublikacjaAn imaging polarimeter based on the principles of high-accuracy polarimetry well known in crystal optics is proposed. The application of scientific digital cameras for performance light measurements leads to precise data on polarizers quality, i.e., maps of extinction ratio and transmission axis. Processing of numerous images, acquired at various settings in the polarizer-sample-analyser system, allows to determine the two-dimensional...
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Using the ultrasonic tomography method to study the condition of wooden beams from historical buildngs
PublikacjaThe need to evaluate the integrity of wooden structural elements is constantly increasing. Non-destructive methods are becoming more popular in this field of research. One type of non-destructive testing is the ultrasonic imaging method, which allows the analysis of internal wood structures without disturbing their state and integrity. In this study, we are interested in assessing the effect of wood condition on the ultrasound...
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A Conformal Circularly Polarized Series-Fed Microstrip Antenna Array Design
PublikacjaA conformal circularly polarized series-fed microstrip array design for broadside radiation is presented. The array aperture under design is conformal to a cylindrical surface of a given radius. The approach we present primarily addresses focusing of the circularly polarized major lobe of the conformal array by proper dimensioning of the aperture spacings. The proposed analytical models yield the values of the element spacings...
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The role of low-energy electrons in the charging process of LISA test masses
PublikacjaThe estimate of the total electron yield is fundamental for our understanding of the test-mass charging associated with cosmic rays in the Laser Interferometer Space Antenna (LISA) Pathfinder mission and in the forthcoming gravitational wave observatory LISA. To unveil the role of low energy electrons in this process owing to galactic and solar energetic particle events, in this work we study the interaction of keV and sub-keV...
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Simulation of the response of base-isolated buildings under earthquake excitations considering soil flexibility
PublikacjaThe accurate analysis of the seismic response of isolated structures requires the incorporation of the flexibility of supporting soil. However, it is often customary to idealize the soil as rigid during the analysis of such structures. In the present paper, seismic response time history analyses of base-isolated buildings modelled as single degree-of-freedom (SDOF) and multi degree-of-freedom (MDOF) systems with linear and nonlinear...
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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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Fast multi-objective optimization of antenna structures by means of data-driven surrogates and dimensionality reduction
PublikacjaDesign of contemporary antenna structures needs to account for several and often conflicting objectives. These are pertinent to both electrical and field properties of the antenna but also its geometry (e.g., footprint minimization). For practical reasons, especially to facilitate efficient optimization, single-objective formulations are most often employed, through either a priori preference articulation, objective aggregation,...
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Cost-Efficient Globalized Parameter Optimization of Microwave Components through Response-Feature Surrogates and Nature-Inspired Metaheuristics
PublikacjaDesign of contemporary microwave devices predominantly utilizes computational models, including both circuit simulators, and full-wave electromagnetic (EM) evaluation. The latter constitutes the sole generic way of rendering accurate assessment of the system outputs that considers phenomena such as cross-coupling or radiation and dielectric losses. Consequently, for reliability reasons, the final tuning of microwave device parameters...
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Linear-scaling calculation of Hartree-Fock exchange energy with Non-orthogonal Generalised Wannier Functions
PublikacjaWe present a method for the calculation of four-centre two-electron repulsion integrals in terms of localised non-orthogonal generalised Wannier functions (NGWFs). Our method has been imple- mented in the ONETEP program and is used to compute the Hartree-Fock exchange energy component of Hartree-Fock and Density Functional Theory (DFT) calculations with hybrid exchange-correlation functionals. As the NGWFs are optimised in situ...
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Design of a Coplanar Waveguide-Fed Wideband Compact-Size Circularly Polarized Antenna and polarization-sense alteration
PublikacjaThis paper presents the design and validation of a geometrically simple circularly polarized(CP) structure featuring flat gain in the sub-6 GHz 5th generation spectrum. The proposed structure is based on coplanar-waveguide-fed, modified wide slot etched in the ground plane. For generating CP waves, the coplanar ground planes are designed with slight asymmetry in both the horizontal and vertical directions. Furthermore, the ground...
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Supervised-learning-based development of multi-bit RCS-reduced coding metasurfaces
PublikacjaCoding metasurfaces have been introduced as efficient tools allowing meticulous control over the electromagnetic (EM) scattering. One of their relevant application areas is radar cross section (RCS) reduction, which principally relies on the diffusion of impinging EM waves. Despite its significance, careful control of the scattering properties poses a serious challenge at the level of practical realization. This article is concerned...
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A new index for statistical analyses and prediction of travelling ionospheric disturbances
PublikacjaTravelling Ionospheric Disturbances (TIDs) are signatures of atmospheric gravity waves (AGWs) observed in changes in the electron density. The analysis of TIDs is relevant for studying coupling processes in the thermosphere–ionosphere system. A new TID index is introduced, which is based on an easy extension of the commonly used approach for TID detection. This TID activity index, which can be applied for individual Global Navigation...
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Analiza wezbrania rzeki Kaczej w Gdyni po opadzie z 14 lipca 2016 roku
PublikacjaW połowie lipca 2016 r. w Trójmieście, zanotowano opad atmosferyczny o sumie przekraczającej 150 mm. Opadom deszczu od godzin popołudniowych dnia 14 lipca do godzin rannych 15 lipca towarzyszył okresami bardzo silny i gwałtowny wiatr początkowo z kierunku północno-wschodniego następnie z kierunku północno-zachodniego. Opisana sytuacja hydro-meteorologiczna spowodowała znaczne wezbrania w rzekach i potokach rejonu Zatoki Gdańskiej,...
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Images of the Seabed of the Gulf of Gdansk Obtained by Means of the Parametric Sonar
PublikacjaThe main goal of this paper is to present results of the experimental investigation of the seabed by means of parametric echosounder in the form of chosen images. The phenomena of nonlinear interaction between two parallel beams of high intensity gives as a results very narrow beam of low frequency wave, that enables to penetrate the sea bottom. The first step of our investigations was calibration of all the elements of the measuring...
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An analysis of solar energy conversion systems based on photon and thermal processes
PublikacjaSolar spectral irradiance covers a fairly broad wavelength range. Solar radiation is part of the electromagnetic spectrum which is described by the concept of wave-particle duality. The corpuscular theory of electromagnetic radiation states that energy is transmitted by photons. Photons carry specific amounts of energy which can be used to convert solar energy into other types of energy, in particular electricity. The internal...
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Multi-objective optimization of compact UWB impedance matching transformers using Pareto front exploration and adjoint sensitivities
PublikacjaIn this paper, a technique for fast multi-objective optimization of impedance matching transformers has been presented. In our approach, a set of alternative designs that represent the best possible trade-offs between conflicting objectives (here, the maximum reflection level within a frequency band of interest and the circuit size) is identified by directly exploring the Pareto front. More specifically, the subsequent Pareto-optimal...
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Modelling and simulations in time-fractional electrodynamics based on control engineering methods
PublikacjaIn this paper, control engineering methods are presented with regard to modelling and simulations of signal propagation in time-fractional (TF) electrodynamics. That is, signal propagation is simulated in electromagnetic media described by Maxwell’s equations with fractional-order constitutive relations in the time domain. We demonstrate that such equations in TF electrodynamics can be considered as a continuous-time system of...
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Detection of gaseous compounds with different techniques
PublikacjaSensing technology has been developed for detection of gases in some environmental, industrial, medical, and scientific applications. The main tasks of these works is to enhance performance of gas sensors taking into account their different applicability and scenarios of operation. This paper presents the descriptions, comparison and recent progress in some existing gas sensing technologies. Detailed introduction to optical sensing...
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Analysis of the Hydrodynamic Properties of the 3-Column Spar Platform for Offshore Wind Turbines
PublikacjaThe article presents a design of a floating platform for offshore wind turbines. The concept is a modification of the Spar design and consists of three variable section columns connected to each other by a ballast tank in the lower part of the platform. This solution makes it possible to influence the position of the centre of buoyancy and the centre of mass of the structure. Compared to the classic Spar platform structure, the...