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Search results for: WEAKLY CONNECTED DOMINATION
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Minimization of the number of periodic points for smooth self-maps of closed simply-connected 4-manifolds
PublicationLet M be a smooth closed simply-connected 4-dimensional manifold, f be a smooth self-map of M with fast grow of Lefschetz numbers and r be a product of different primes. The authors calculate the invariant equal to the minimal number of r-periodic points in the smooth homotopy class of f.
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An algorithmic approach to estimating the minimal number of periodic points for smooth self-maps of simply-connected manifolds
PublicationFor a given self-map f of M, a closed smooth connected and simply-connected manifold of dimension m 4, we provide an algorithm for estimating the values of the topological invariant D^m_r [f], which equals the minimal number of r-periodic points in the smooth homotopy class of f. Our results are based on the combinatorial scheme for computing D^m_r [f] introduced by G. Graff and J. Jezierski [J. Fixed Point Theory Appl. 13 (2013),...
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Feedback Control of Doubly-Fed Generator Connected to Current Source Converter
PublicationDoubly-fed induction generator (DFIG) system supplied by current source converter (CSC) is considered in this article. The DFIG can work in two independent modes: AC grid connection and stand-alone mode. The DFIG is connected to the ac grid directly through its stator and the CSC links the rotor side. In this mode, the active and reactive powers of the DFIG must be controlled. This article proposes two control system structures...
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New hybrid quadrature schemes for weakly singular kernels applied to isogeometric boundary elements for 3D Stokes flow
PublicationThis work proposes four novel hybrid quadrature schemes for the efficient and accurate evaluation of weakly singular boundary integrals (1/r kernel) on arbitrary smooth surfaces. Such integrals appear in boundary element analysis for several partial differential equations including the Stokes equation for viscous flow and the Helmholtz equation for acoustics. The proposed quadrature schemes apply a Duffy transform-based quadrature...
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Computations of the least number of periodic points of smooth boundary-preserving self-maps of simply-connected manifolds
PublicationLet $r$ be an odd natural number, $M$ a compact simply-connected smooth manifold, $\dim M\geq 4$, such that its boundary $\partial M$ is also simply-connected. We consider $f$, a $C^1$ self-maps of $M$, preserving $\partial M$. In [G. Graff and J. Jezierski, Geom. Dedicata 187 (2017), 241-258] the smooth Nielsen type periodic number $D_r(f;M,\partial M)$ was defined and proved to be equal to the minimal number of $r$-periodic points...
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The computational complexity of the backbone coloring problem for bounded-degree graphs with connected backbones
PublicationGiven a graph G, a spanning subgraph H of G and an integer λ>=2, a λ-backbone coloring of G with backbone H is a vertex coloring of G using colors 1, 2, ..., in which the color difference between vertices adjacent in H is greater than or equal to lambda. The backbone coloring problem is to find such a coloring with maximum color that does not exceed a given limit k. In this paper, we study the backbone coloring problem for bounded-degree...
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Combinatorial scheme of finding minimal number of periodic points for smooth self-maps of simply connected manifolds
PublicationLet M be a closed smooth connected and simply connected manifold of dimension m at least 3, and let r be a fixed natural number. The topological invariant D^m_r [f], defined by the authors in [Forum Math. 21 (2009), 491-509], is equal to the minimal number of r-periodic points in the smooth homotopy class of f, a given self-map of M. In this paper, we present a general combinatorial scheme of computing D^m_r [f] for arbitrary dimension...
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Analysis of an Energy Management System of a Small Plant Connected to the Rural Power System
PublicationThis paper presents the analysis of an energy management system (EMS) implemented to fulfill the requirements of a microgrid (MG) power supply owned by a small industrial company and connected to the rural power system. The main goal of this system is to ensure connection with the existing rural power system in terms of energy exchange, as well as to perform islanding mode operation of the microgrid based on the energy demand of...
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Graphs with convex domination number close to their order
PublicationW pracy opisane są grafy z liczbą dominowania wypukłego bliską ilości ich wierzchołków.
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Lower bound on the paired domination number of a tree
PublicationW pracy przedstawione jest ograniczenie dolne dla liczby dominowania parami oraz scharakteryzowane są wszystkie drzewa ekstremalne.
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Weakly nonlinear dynamics of short acoustic waves in exponentially stratified gas
PublicationRozpatruje się dynamika krótkich (w porównywaniu z charakterystyczną skalą zmiany gęstości gazu atmosferycznego) fal akustycznych. Wyprowadzone nowe równanie ewolucyjne, które uwzględnia dyspersję i nieliniowy charakter propagacji tych fal. Porównuje sie liniowa i nieliniowa dynamika. Ilustracje propagacji, numeryczne wyliczione na podstawie nowych wzorów, są przedstawione. Indexed and abstracted (from vol. 32(1) 2007) in Science...
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NP-completeness of convex and weakly convex domiating set decision problems.
PublicationLiczby dominowania wypukłego i słabo wypukłego są nowymi rodzajami liczb dominowania. W tym artykule pokazujemy, że problemy decyzyjne dominowania wypukłegi i słabo wypukłego są NP-zupełne w przypadku grafów dwudzielnych oraz split grafów. Posługując się zmodyfikowanym algorytmem Washalla możemy w czasie wielomianowym określić, czy dany podzbiór wierzchołków grafu jest spójny bądź słabo spójny.
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Fixed point theorems for weakly commuting and compatible multi-valued mappings.
PublicationW pracy podano twierdzenia o wspólnych punktach stałych czwórki odwzorowań: dwóch jednowartościowych T i S oraz dwóch wielowartościowych F i G, spełniających nieliniowy uogólniony warunek kontrakcyjny, przy pewnych założeniach dotyczących uogólnionej komutatywności T,S i F,G. W pracy zamieszczono przykłady ilustrujące udowodnione twierdzenia.
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Connected components of the space of proper gradient vector fields
PublicationWe show that there exist two proper gradient vector fields on Rn which are homotopic in the category of proper maps but not homotopic in the category of proper gradient maps.
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Assessment of risks connected with economic activity in the SME sector
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Voltage Conditions in Low Voltage Grid with Connected Mictogeneration
PublicationThe introduction of distributed generation into a low voltage grid may cause voltage problems in it. The paper discusses the effect of microgeneration on voltage levels in a low voltage grid. A real low voltage grid of considerable length was selected for the analysis. The grid primarily supplies residential buildings in a rural area. Results of tests that consider potential measures which could be applied in this grid to improve...
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Porous structure of clinoptilolite and problems connected with its characterization.
PublicationPrzedstawiono: stan wiedzy nt technik oznaczania porowatości i powierzchni właściwej różnego typu materiałów, oraz wyniki badań fizykochemicznych naturalnych zeolitów pochodzących z obszaru Zakarpacia (Ukraina).
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Algebraic periods and minimal number of periodic points for smooth self-maps of 1-connected 4-manifolds with definite intersection forms
PublicationLet M be a closed 1-connected smooth 4-manifolds, and let r be a non-negative integer. We study the problem of finding minimal number of r-periodic points in the smooth homotopy class of a given map f: M-->M. This task is related to determining a topological invariant D^4_r[f], defined in Graff and Jezierski (Forum Math 21(3):491–509, 2009), expressed in terms of Lefschetz numbers of iterations and local fixed point indices of...
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Reducing the number of periodic points in the smooth homotopy class of a self-map of a simply-connected manifold with periodic sequence of Lefschetz numbers
PublicationLet f be a smooth self-map of an m-dimensional (m >3) closed connected and simply-connected manifold such that the sequence of the Lefschetz num- bers of its iterations is periodic. For a fixed natural r we wish to minimize, in the smooth homotopy class, the number of periodic points with periods less than or equal to r. The resulting number is given by a topological invariant J[f] which is defned in combinatorial terms and is...
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Induction Generator with Direct Control and a Limited Number of Measurements on the Side of the Converter Connected to the Power Grid
PublicationThe article presents an induction generator connected to the power grid using the AC/DC/AC converter and LCL coupling filter. Three-level inverters were used in the converter, both from the generator side and the power grid side. The algorithm realizing Pulse Width Modulation (PWM) in inverters has been simplified to the maximum. Control of the induction generator was based on the Direct Field-Oriented Control (DFOC) method. At...
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Improved Modeling of Microwave Structures Using Performance-Driven Fully-Connected Regression Surrogate
PublicationFast replacement models (or surrogates) have been widely applied in the recent years to accelerate simulation-driven design procedures in microwave engineering. The fundamental reason is a considerable—and often prohibitive—CPU cost of massive full-wave electromagnetic (EM) analyses related to solving common tasks such as parametric optimization or uncertainty quantification. The most popular class of surrogates are data-driven...
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Joanna Raczek dr inż.
PeopleEmployment 2003 -- 2019: Faculty of Applied Physics and Mathematics, Gdańsk University of Technology. 2019 - present: Faculty of Electronic, Informatics and Telecominications, Gdańsk University of Technology. Education May 2007: Doctor of Philosophy in Mathematics, University of Gdańsk. Doctoral dissertation: "Paired domination and doubly domination in graphs". Supervisor: dr hab. Jerzy Topp. 2000 -- 2004 Bachelor of Science...
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Lower bound on the distance k-domination number of a tree
PublicationW artykule przedstawiono dolne ograniczenie na liczbę k-dominowania w drzewach oraz scharakteryzowano wszystkie grafy ekstremalne.
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Domination numbers in graphs with removed edge or set of edges
PublicationW artykule przedstawiony jest wpływ usuwania krawędzi lub zbioru krawędzi na liczby dominowania spójnego i słabo spójnego.
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Nordhaus-Gaddum results for the convex domination number of a graph
PublicationPraca dotyczy nierówności typu Nordhausa-Gadduma dla dominowania wypukłego.
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Interfacial behavior of polar, weakly polar, and nonpolar compounds bound to activated carbons
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Packing Three-Vertex Paths in 2-Connected Cubic Graphs
PublicationW pracy rozważano problem rozmieszczanie ścieżek P3 w 2-spójnych grafach 3-regularnych. Pokazano, że w 2-spójnym grafie 3-regularnym o n wierzchołkach można zawsze pokryć 9/11 n wierzchołków przez ścieżki P3; podano także odpowiednie oszacowania górne.
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Low Frequency Conducted Emissions of Grid Connected Static Converters
PublicationPulse-width modulated rectifiers are nowadays commonly used for AC to DC power conversion. PWM rectification technology is very effective and allows for bidirectional power flow with the possibility of power factor improvement and low-order harmonic emission limitation. Unfortunately, employed PWM boost topology results with generation of input current harmonic distortions in a frequency range tightly correlated to modulation frequency....
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SAE International Journal of Connected and Automated Vehicles
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Weakly non-local theories of damage and plasticity based on balance of dissipative material forces
PublicationWykazano, że założenie o siłach materialnych oraz odpowiadających im równaniach równowagi w połączeniu z klasycznymi prawami dynamiki w przestrzeni fizycznej, pozwoliło na sformułowanie teoretycznych podstaw w zakresie słabo-nielokalnych gradientowych modeli zniszczenia i plastyczności. Odpowiednie równania równowagi w przestrzeni fizycznej i materialnej oraz pierwsze i drugie prawo termodynamiki zapisano w postaci całkowej. Następnie...
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Numerical modelling of water transport processes in partially-connected tidal basins
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Investor focused placement and sizing of photovoltaic grid-connected systems in Pakistan
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Minimal number of periodic points for smooth self-maps of simply-connected manifolds
Open Research DataThe problem of finding the minimal number of periodic points in a given class of self-maps of a space is one of the central questions in periodic point theory. We consider a closed smooth connected and simply-connected manifold of dimension at least 4 and its self-map f. The topological invariant D_r[f] is equal to the minimal number of r-periodic points...
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All graphs with restrained domination number three less than their order
PublicationW pracy opisana jest rodzina wszystkich grafów, dla których liczbadominowania zewnętrznego jest o trzy mniejsza od ich rzędu.
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Anion–water interactions of weakly hydrated anions: molecular dynamics simulations of aqueous NaBF4 and NaPF6
PublicationIn aqueous ionic solutions, both the structure and the dynamics of water are altered dramatically with respect to the pure solvent. The emergence of novel experimental techniques makes these changes accessible to detailed investigations. At the same time, computational studies deliver unique possibilities for the interpretation of the experimental data at the molecular level. Here, using molecular dynamics simulations, we demonstrate...
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Key activities to improve energy management in DC microgrids connected by urban traction
PublicationDC MicroGrids must have Energy Management Systems to guarantee efficient, dependable, and environmentally friendly electricity. The application of Model Predictive Control, proved to be helpful due to its adaptability and capacity to use non-linear models. This paper, based on an extensive literature review, identifies and discusses the three key activities to improve the characteristics of DC MicroGrids, i.e.: the use of Energy...
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Numerical simulation of temperature distribution of heat flow on reservoir tanks connected in a series
PublicationThe flow of temperature distribution through a medium in thermodynamic studies plays an important role in understanding physical phenomena in chemical science and petroleum engineering, while temperature distribution indicates the degree of reaction that must be undergone to obtain the final product. Therefore, this paper aims to present and apply the exponential matrix algorithm (EMA), differential transformation algorithm (DTA),...
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Minimizing the number of periodic points for smooth maps. Non-simply connected case
PublicationNiech f będzie gładkim odwzorowaniem zamkniętej rozmaitości o wymiarze wiekszym niż 2, a r ustaloną liczbą naturalną. W artykule zdefiniowany został niezmiennik topologiczny równy minimalnej liczbie punktów r-periodycznych w gładkiej klasie homotopii f.
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Excitation energy migration in uniaxially oriented polymer films: a comparison between strongly and weakly organized systems
PublicationMechanizm wieloetapowej migracji energii w osiowo rozciąganych foliach polimerowych jest analizowany w układach o silnej i słabej orientacji molekuł barwników umieszczonych w matrycach poliwinylowych. Porównanie tych różnie orientujących się układów bazuje na zjawisku depolaryzacji stężeniowej anizotropii emisji, symulacjach Monte Carlo i wartościach liniowego dichroizmu. Pokazano, że uporządkowanie momentów przejścia fluoroforów...
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The domination of ionic conductivity in tetragonal phase of the organometal halide perovskite CH3NH3PbI3-xClx
PublicationOrganometal trihalide perovskites have recently gained extreme attention due to their high solar energy conversion in photovoltaic cells. Here, we investigate the contribution of iodide ions to a total conductivity of the mixed lead halide perovskite CH3NH3PbI3−xClx with a use of the modified DC Hebb–Wagner polarization method. It has been identified that an ionic conductivity dominates in tetragonal phase which is associated with room...
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Cascaded doubly fed induction generator for mini and micro power plants connected to grid
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Chiral Molecular Cages Based on Cyclotriveratrylene and Sucrose Units Connected with p ‐Phenylene Linkers
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Innovative consciousness and threats estimation connected with implementation of innovations to SMEs cooperating with shipbuilding industry
PublicationPodejmowanie działań innowacyjnych przez małe i średnie przedsiębiorstwa nie jest szeroko rozpowszechnione. Wynika to, między innymi, ze specyfiki tego sektora. MSP często dysponują ograniczonymi środkami finansowymi i nisko wykwalifikowanymi pracownikami, co stanowi w wielu przypadkach barierę we wprowadzaniu innowacji. Nie mniej istotne są inne podmioty działające w otoczeniu MSP włączające się w realizacje procesu innowacyjnego....
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Estimates for minimal number of periodic points for smooth self-maps of simply-connected manifolds
Open Research DataWe consider a closed smooth connected and simply-connected manifold of dimension at least 4 and its self-map f. The topological invariant Dr[f] is equal to the minimal number of r-periodic points in the smooth homotopy class of f. We assume that r is odd and all coefficients b(k) of so-called periodic expansion of Lefschetz numbers of iterations are...
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Non-Adaptive Speed and Position Estimation of Doubly-Fed Induction Generator in Grid-Connected Operations
PublicationThe nonadaptive speed and position estimation scheme for a doubly-fed induction generator (DFIG) is presented in this article. The observer structure is based on the extension of the mathematical model of DFIG to the introduced H vector. Based on the defined H vector, the nonadaptive position and speed estimation is proposed. The Lyapunov method is extended to the practical stability theorem to stabilize the structure. The classic...
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Connected early-career experiences of equality in academia during the pandemic and beyond: Our liminal journey
PublicationIn this paper, we draw on our subjective experiences as two female early-career academics during the global COVID-19 pandemic. While we acknowledge that the pandemic had negative implications for many female scholars due to compulsory telework or increased family responsibilities, we also want to shed light on the empowering experiences shaped by collegial support that became an important part of our pandemic story. We build on...
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Stability Enhancement of Grid-Connected Wind Power Generation System Using PSS, SFCL and STATCOM
PublicationThe stability related issues may occur in a power system due to disturbances in generating or loading conditions, especially in the presence of distributed generation (DG) based on renewable energy resources (RERs). This paper proposes a novel strategy for the stability enhancement of a wind power generation system (WPGS) by using a combination of three devices, namely, a power system stabilizer (PSS), resistive superconductor...
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An Extended Control of the Input Angle for Matrix Converters Connected with the Non-Unity Power Factor Loads.
PublicationThis paper proposes a novel PWM modulation algorithm for Multiphase Conventional Matrix Converters (MCMC), with 3 inputs and k outputs, using the transfer function of the load angle. The proposed approach extends the range of power angle control at the input during the operation with a maximum voltage transfer ratio. The proposed concept is based on the Direct Analytic Voltage PWM (DAV--PWM) modulation with an elliptical trajectory...
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T-House. Shaping Ergonomic and Flexible Interiors in Modular Form Connected to Horticultural Therapy Zone
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Minimal number of periodic points for C^1 self-maps of compact simply-connected manifolds
PublicationNiech f będzie odwzorowaniem gładkiej zwartej i jednospójnej rozmaitości o wymiarze większym lub równym 3. W pracy zdefiniowany został topologiczny niezmiennik będący najlepszym dolnym oszacowaniem liczby punktów periodycznych w klasie gładkich odwzorowań homotopijnych z f.