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Search results for: PERIODIC BOUNDARY CONDITIONS
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Modelling of Hydraulic Fracturing in Rocks in Non-isothermal Conditions Using Coupled DEM/CFD Approach with Two-Phase Fluid Flow Model
PublicationSkała łupkowa jest materiałem silnie niejednorodnym, nieciągłym i porowatym. W warunkach nieizotermicznych ruch płynu w układzie porów i kapilar jest silnie sprzężony z przenoszeniem ciepła. Przebieg szczeliny hydraulicznej silnie zależy od stopnia nasycenia skały. Opracowano innowacyjny model termo-hydro-mechaniczny oparty na modelu DEM w celu szczegółowego śledzenia frakcji ciecz/gaz w porach i pęknięciach pod kątem ich różnej...
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Linear Pantographic Sheets: Existence and Uniqueness of Weak Solutions
Publicationwe address the well-posedness of the planar linearized equilibrium problem for homogenized pantographic lattices. To do so: (i) we introduce a class of subsets of anisotropic Sobolev’s space as the most suitable energy space E relative to assigned boundary conditions; (ii) we prove that the considered strain energy density is coercive and positive definite in E ; (iii) we prove that the set of placements for which the strain...
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Buckling Analysis of a Micro Composite Plate with Nano Coating Based on the Modified Couple Stress Theory
PublicationThe present study investigates the buckling of a thick sandwich plate under the biaxial non-uniform compression using the modified couple stress theory with various boundary conditions. For this purpose, the top and bottom faces are orthotropic graphene sheets and for the central core the isotropic soft materials are investigated. The simplified first order shear deformation theory (S-FSDT) is employed and the governing differential...
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Clarke duality for Hamiltonian systems with nonstandard growth
PublicationWe consider the existence of periodic solutions to Hamiltonian systems with growth conditions involving G-function. We introduce the notion of symplectic G-function and provide relation for the growth of Hamiltonian in terms of certain constant CG associated to symplectic G-function G. We discuss an optimality of this constant for some special cases. We also provide applications to the Φ-laplacian type systems.
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Thermal Buckling Analysis of Circular Bilayer Graphene sheets Resting on an Elastic Matrix Based on Nonlocal Continuum Mechanics
PublicationIn this article, the thermal buckling behavior of orthotropic circular bilayer graphene sheets embedded in the Winkler–Pasternak elastic medium is scrutinized. Using the nonlocal elasticity theory, the bilayer graphene sheets are modeled as a nonlocal double–layered plate that contains small scale effects and van der Waals (vdW) interaction forces. The vdW interaction forces between the layers are simulated as a set of linear springs...
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On instabilities and post-buckling of piezomagnetic and flexomagnetic nanostructures
PublicationWe focus on the mechanical strength of piezomagnetic beam-like nanosize sensors during post-buckling. An effective flexomagnetic property is also taken into account. The modelled sensor is selected to be a Euler-Bernoulli type beam. Long-range interactions between atoms result in a mathematical model based on the nonlocal strain gradient elasticity approach (NSGT). Due to possible large deformations within a post-buckling phenomenon,...
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Designing Atomic Resonance Conditions for $^{93m}$Mo Isomer Depletion Via Nuclear Excitation by Electron Capture in a Beam-based Scenario for Selected Targets
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Biogeochemical and mineralogical effects of Fe-P-S dynamics in sediments of continental shelf sea: Impact of salinity, oxygen conditions, and catchment area characteristics
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Impact of the Cultivation System and Pre-Sprouting of Selected Potato Cultivars on the Physico-Chemical Properties and Enzymatic Activity of Soil in the Conditions of Central-Eastern Poland
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Has a High Dose of Vitamin D3 Impacted Health Conditions in Older Adults?—A Systematic Review and Meta-Analysis Focusing on Dose 100,000 IU
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Modelling of SO2 and NOx Emissions from Coal and Biomass Combustion in Air-Firing, Oxyfuel, iG-CLC, and CLOU Conditions by Fuzzy Logic Approach
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Analysis of Cutting Force and Power Under the Conditions of Minimized Cooling in the Process of Turning AISI-1045 Steel with the Use of the Parameter Space Investigation Method
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Regulacja osi toru w warunkach pomiarów satelitarnych :(program badań) = Geometrical adjustment of the railway track in the conditions of the satellite surveying : (research program)
PublicationW pracy zwrócono uwagę na uwarunkowania związane z zastosowaniem technik pomiarów satelitarnych GPS w pomiarach inwentaryzacyjnych linii kolejowych. Wskazano na konieczność nawiązania współpracy pomiędzy specjalistami z dziedziny pomiarów satelitarnych i środowiskiem kolejowym. Może to spowodować radykalną poprawę w zakresie poziomu utrzymania kształtu geometrycznego torów, gdzie występująca obecnie sytuacja budzi poważne zastrzeżenia....
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A method for evaluating the performance of a marine piston internal combustion engine used as the main engine on a ship during its voyage in different sailing conditions
PublicationPrzedstawiono metodę oceny działania tłokowych silników spalinowych napędu głównego staków morskich, nazywanych silnikami głównymi, działających w typowych warunkach ich eksploatacji. Warunki te zostały opisane z uwzględnieniem pola osiągów tego rodzaju silników. Metoda ta umożliwia obliczenie wartości działania w wyniku zastosowania rachunku całkowego. Znamienne jest to, że działanie wspomnianych silników spalinowych zostało przyrównane...
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Influence of adjustment of gas turbine controller on ship propulsion system behaviour in rough sea conditions. Part 1. The dynamic model of propulsion system.
PublicationPrzedstawiono model dynamiki układu napędowego okrętowego, wykorzystując metodę elementów skończonych. Układ napędowy składa się z dwóch turbin gazowych napędzających poprzez przekładnię mechaniczną zębatą pędnik o nastawnym skoku. W symulacji układu napędowego można zadawać wymuszenia wartością zadaną nastaw prędkości na regulatorze, wymuszenia od falowania morza w zależności od stanu morza, jak również zmianą ustawienia skoku...
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Fractional Problems with Right-Handed Riemann-Liouville Fractional Derivatives
PublicationIn this paper, we investigate the existence of solutions for advanced fractional differential equations containing the right-handed Riemann-Liouville fractional derivative both with nonlinear boundary conditions and also with initial conditions given at the end point T of interval [0,T ]. We use both the method of successive approximations, the Banach fixed point theorem and the monotone iterative technique, as well. Linear problems...
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Bernstein-type theorem for ϕ-Laplacian
PublicationIn this paper we obtain a solution to the second-order boundary value problem of the form \frac{d}{dt}\varPhi'(\dot{u})=f(t,u,\dot{u}), t\in [0,1], u\colon \mathbb {R}\to \mathbb {R} with Sturm–Liouville boundary conditions, where \varPhi\colon \mathbb {R}\to \mathbb {R} is a strictly convex, differentiable function and f\colon[0,1]\times \mathbb {R}\times \mathbb {R}\to \mathbb {R} is continuous and satisfies a suitable growth...
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Estimation of Stresses in a Dry Sand Layer Tested on Shaking Table
PublicationTheoretical analysis of shaking table experiments, simulating earthquake response of a dry sand layer, is presented. The aim of such experiments is to study seismic-induced compaction of soil and resulting settlements. In order to determine the soil compaction, the cyclic stresses and strains should be calculated first. These stresses are caused by the cyclic horizontal acceleration at the base of soil layer, so it is important...
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On asymptotic periodicity of kernel double Markovian operators
PublicationIt is proved that a kernel, doubly Markovian operator T is asymptotically periodic if and only if its deterministic σ-field Σd(T)(equivalently Σd(T∗)) is finite. It follows that kernel doubly Markovian operator T is asymptotically periodic if and only if T∗ is asymptotically periodic.
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Temperature influences on shear stability of a nanosize plate with piezoelectricity effect
PublicationPurpose The purpose of this paper is to predict the mechanical behavior of a piezoelectric nanoplate under shear stability by taking electric voltage into account in thermal environment. Design/methodology/approach Simplified first-order shear deformation theory has been used as a displacement field. Modified couple stress theory has been applied for considering small-size effects. An analytical solution has been taken into account...
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Transient response of oscillated carbon nanotubes with an internal and external damping
PublicationThe present works aims at modeling a viscoelastic nanobeam with simple boundary conditions at the two ends with the introduction of the Kelvin-Voigt viscoelasticity in a nonlocal strain gradient theory. The nanobeam lies on the visco-Pasternak matrix in which three characteristic parameters have a prominent role. A refined Timoshenko beam theory is here applied, which is only based on one unknown variable, in accordance with the...
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Analytical predictions for the buckling of a nanoplate subjected to non-uniform compression based on the four-variable plate theory
PublicationIn the present study, the buckling analysis of the rectangular nanoplate under biaxial non-uniform compression using the modified couple stress continuum theory with various boundary conditions has been considered. The simplified first order shear deformation theory (S-FSDT) has been employed and the governing differential equations have been obtained using the Hamilton’s principle. An analytical approach has been applied to obtain...
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Ewa Klugmann-Radziemska prof. dr hab.
PeopleEwa Klugmann-Radziemska graduated from the University of Gdansk with a degree in physics, and since 1996 has been associated with the Gdansk University of Technology, when she began PhD studies. Currently, he is a professor at the Faculty of Chemistry at the Gdansk University of Technology, since 2006 head of the Department of Chemical Apparatus and Machinery. In the years 2008–2016 she was the Vice-Dean for cooperation and development,...
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Nonlinear generation of non-acoustic modes by low-frequency sound in a vibrationally relaxing gas
PublicationTwo dynamic equations referring to a weakly nonlinear and weakly dispersive flow of a gas in which molecular vibrational relaxation takes place. are derived. The first one governs an excess temperature associated with the thermal mode, and the second one describes variations in vibrational energy. Both quantities refer to non-wave types of gas motion. These variations are caused by the nonlinear transfer of acoustic energy into...
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Optimal conditions of ramentaceone and plumbagin separation and isolation from carnivorous plants extracts using reverse phase-high performance liquid chromatography (RP-HPLC)
PublicationPreparatywna chromatografia cieczowa jest szczególnie przydatną techniką do rozdzielania i izolacji użytecznych ilości substancji z różnych skomplikowanych mieszanin. Praca prezentuje optymalne warunki rozdzielania i izolacji ramentaceonu i plumbaginy uwzględniając maksymalną selektywność rozdzielania naftochinonów od substancji balastowych z chloroformowych ekstraktów roślinnych D. aliciae i D. capensis z zastosowaniem techniki...
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Optimal conditions of ramentaceone and plumbagin separation and isolation from carnivorous plants extracts using normal phase-high performance liquid chromatography (NP-HPLC)
PublicationPraca prezentuje optymalne warunki rozdzielania i izolacji plumbaginy i ramentacenu z matrycy analitycznej, którą stanowią chloroformowe ekstrakty z roślin D.aliciae i D.capensis z wykorzystaiem techniki NP-HPLC. Skład eluentu dla żelu krzemionkowego jako fazy stacjonarnej był optymalizowany. Zostały przedstawione optymalne warunki powiększania skali procesu izolacji badanych metabolitów z ekstrakrów roślinnych. Określono również...
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Regionalne obserwatorium kultury w wojewwdztwie podlaskim - uwarunkowania i planowane kierunki rozwoju (Regional Cultural Observatory in the Podlaskie Voivodeship - Conditions and Development Trends)
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Wpływ warunków hydraulicznych w sieci wodociągowej na wtórne zanieczyszczenie wody = Effect of hydraulic conditions in the water distribution system on the secondary water pollution
PublicationCelem badań jest próba empirycznego wykazania wpływu zmian prędkości i czasu przebywania wody w przewymiarowanej sieci wodociągowej na wtórne jej zanieczyszczenie. Podstawą analizy są pomiary hydrauliczne wykonane podczas realizacji płukania rurociągów żeliwnych D=100 mm oraz badania laboratoryjne popłuczyn w zakresie suchej pozostałości, w tym zawartości związków żelaza. Każdą pobraną próbkę popłuczyn z hydrantów poddano szczegółowej...
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Określenie szybkości korozji stopu AlSi13Mg1CuNi nadtopionego laserowo w warunkach kriogenicznych = Corrosion rate determination of AlSi13Mg1CuNi alloy laser remelted at cryogenic conditions
PublicationW pracy przedstawiono wyniki badania szybkości korozji stopu AlSi13Mg1CuNi nadtopionego laserowo w warunkach kriogenicznych. Stop eksponowano w 0,01 M roztworze kwasu siarkowego H2SO4
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Comparisson of area specific resistance of the SrTi1-xFexO3-d porous oxygen electrodes and state-of-the-art LSCF sintered at optimal conditions
Open Research DataIn this dataset are presented results of the polarization resistance of optimaly sintered SrTi1-xFexO3-d porous oxygen electrodes in symetrical cell (1000 °C; 800 °C and 800°C respectively x = 0.35; 0.50 and 0.70). For commparison were selected commercially avilable state-of-the-art LSCF (Europa) sintered at 1050 °C. The measurement temperature range...
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Method of identification of the slide tribological system top layer condition by assessment of the t-02 four-ball tester friction node operation
Publicationa method is proposed of the assessment of t-02 four-ball tester friction node operation during extreme unit loads on the tribological system for identification of the top layer condition in that system lubricated with the tested lubricating oil. by identification of the friction node with a thermodynamic system, that operation is treated as an energy generating process of the created servo-layer structure. the friction node operation...
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Explicit and implicit difefrence methods for quasilinear first order partial functional differential equations.
PublicationInitial boundary value problems of the Dirichlet type for quasilinear functional differential equations are considered. Explicit difference schemes of the Euler type and implicit difference methods are investigated. Suffcient conditions for the convergence of approximate solutions are given and comparisons of the methods are presented. It is proved that assumptions on the regularity of given functions are the same for both classes...
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CLASSIFICATION OF RESTRAINTS IN THE OPTIMIZATION PROBLEM OF A COLD-FORMED PROFILE
PublicationThis work describes the restraints in the optimization problem. This is an important and complicated issue because it requires taking into account a vast range of information related to the design and production. In order to describe the relations of a specific optimization problem, it is essential to adopt appropriate criteria and to collect information on all kinds of restraints, i.e. boundary conditions. The following paper...
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NUMERICAL SIMULATION OF CRATER CREATING PROCESS IN DYNAMIC REPLACEMENT METHOD BY SMOOTH PARTICLE HYDRODYNAMICS
PublicationA theoretical base of SPH method, including the governing equations, discussion of importance of the smoothing function length, contact formulation, boundary treatment and finally utilization in hydrocode simulations are presented. An application of SPH to a real case of large penetrations (crater creating) into the soil caused by falling mass in Dynamic Replacement Method is discussed. An influence of particles spacing on method...
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Novel Analytic-Numerical Model of Free Convection: with Leading Edge Considered
PublicationA novel solution of the free convection boundary problem is represented in analytical form for velocity and temperature for an isothermal vertical plate, as an example. These fields are built as a Taylor Series in the x coordinate with coefficients as functions of the vertical coordinate (y). We restrict ourselves by cubic approximation for both functions. The basic Navier-Stokes and Fourier-Kirchhoff equations and boundary conditions...
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Simulations of flows in the coastal zone of the Baltic Sea
Open Research DataThe study area is located in the Southern Baltic, within Polish Marine Areas, adjacent to the coastline in the vicinity of Lubiatowo village, where The Coastal Research Station (CRS) – a field laboratory of the Institute of Hydro-Engineering of the Polish Academy of Sciences (IBW PAN) –is situated. The numerical reconstruction of the coastal flow was...
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A model of stealth maritime object having some innovative solutions concerning the object form, structure and materials.
Open Research DataThe aim of the project is to work out a model of the stealth maritime object which will have innovative solutions concerning the object form, structure and materials. These solutions should enable a modification of combinations of the object features defining the object stealth characteristics (difficulty of the object detection in the water). It is...
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Mathematical analysis of a generalised p53-Mdm2 protein gene expression model
PublicationWe propose the generalisation of the p53-Mdm2 protein gene expression model introduced by Monk (2003). We investigate the stability of a unique positive steady state and formulate conditions which guarantee the occurrence of the Hopf bifurcation. We show that oscillatory behaviour can be caused not only by time lag in protein transcription process, but also can be present in the model without time delay. Moreover, we investigate...
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Standing Waves in a Rectangular Resonator Containing Acoustically Active Gases
PublicationThe distribution of perturbations of pressure and velocity in a rectangular resonator is considered. A resonator contains a gas where thermodynamic processes take place, such as exothermic chemical reaction or excitation of vibrational degrees of a molecule’s freedom. These processes make the gas acoustically active under some conditions. We conclude that the incident and reflected compounds of a sound beam do not interact in the...
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Approximative sequences and almost homoclinic solutions for a class of second order perturbed Hamiltonian systems
PublicationIn this work we will consider a class of second order perturbed Hamiltonian systems with a superquadratic growth condition on a time periodic potential and a small aperiodic forcing term. To get an almost homoclinic solution we approximate the original system by time periodic ones with larger and larger time periods. These approximative systems admit periodic solutions, and an almost homoclinic solution for the original system...
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Economic conditions for the development of energy efficient civil engineering using RES in the policy of cohesion of the European Union (2014–2020). Case study: The town of Zielona Gora
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Optimization of submerged fermentation conditions for immunosuppressant mycophenolic acid production by Penicillium roqueforti isolated from blue-molded cheeses: enhanced production by ultraviolet and gamma irradiation
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Investigations of quasi-static vortex structures in 2D sand specimen under passive earth pressure conditions based on DEM and Helmholtz-Hodge vector field decomposition.
PublicationArtykuł przedstawia wyniki obliczeń quasi-statycznych struktur wirowych w 2-wymiarowej próbce piasku w warunkach pasywnego parcia gruntu. Zastosowano metodę elementów dyskretnych i dekompozycję Helmholtza-Hodge’a pola wektorowego. Stwierdzono bliską zależność między wirami a miejscem powstania strefy lokalizacji odkształceń stycznych.
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Resonant Frequencies in the Open Microstrip Structures Placed on Curved Surfaces
PublicationThe paper presents the research on open microstrip structures placed on curved surfaces such as cylindrical, elliptical or spherical. The numerical analysis of investigated structures is based on expansion of electric and magnetic fields into suitable function series. Utilizing the continuity conditions the boundary problem is formulated which is solved with the use of method of moments. The investigated structures find application...
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Jerzy Kowalski dr hab. inż.
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Numerical Methods for Partial Differential Equations
e-Learning CoursesCourse description: This course focuses on modern numerical techniques for linear and nonlinear elliptic, parabolic and hyperbolic partial differential equations (PDEs), and integral equations fundamental to a large variety of applications in science and engineering. Topics include: formulations of problems in terms of initial and boundary value problems; finite difference and finite element discretizations; boundary element approach;...
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Firing map for periodically and almost-periodically driven integrate-and-fire models: a dynamical systems approach
PublicationWe consider the Leaky Integrate-and-Fire and Perfect Integrator models of neuron’s dynamics with the input function being periodic and almost-periodic (in the sense of Stepanov). In particular we analyze properties and dynamics of the so-called firing map, which iterations give timings of consecutive spikes of a neuron. In case of a periodic input function we provide a detailed description of the sequence of interspike-intervals,...
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Resonant Frequencies in Microstrip Structure with Omega Medium Substrate
PublicationThe paper presents the research on a rectangular microstrip structure with multilayer substrate containing dielectric and omega medium layers. The effect of pseudochiral medium layer location in the substrate and its thickness on the resonant frequency of the rectangular microstrip structure is investigated. The numerical analysis of investigated structures is based on expansion of electric and magnetic fields. Utilizing the continuity...
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Numerical tests of time-stepping schemes in the context of FEM for 6-field shell dynamics
PublicationThe paper deals with integration of dynamic equations of irregular shells performed with relatively long time steps. Numerical instability appearing often in this kind of analysis motivated the authors to present some studies based on numerical tests referring to convergence problems of finite element analysis as well the applied stability conditions. The analysis is carried out on simulations of shell dynamics with the where the...
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Stanisław Galla dr inż.
PeopleStanisław Galla was born in 1970 in Gdańsk. He graduated from the Secondary Technical School of Mechanical and Electrical Engineering in Gdansk (1990). He studied at the Faculty of Electrical Engineering at Gdansk University of Technology (graduated in 1996). His PhD thesis entitled "Methodology for increasing the accuracy of low frequency measurements of periodic disturbance indicators in low voltage networks" was defended in...