PL
 |
EN
Ograniczanie wyników
Czasopisma help
  1. 20 Przegląd Elektrotechniczny
  2. 9 Computational Methods in Science and Technology
  3. 6 Bulletin of the Polish Academy of Sciences. Technical Sciences
  4. 4 Maszyny Elektryczne : zeszyty problemowe
  5. 3 Mosty
Więcej...
Autorzy help
  1. 64 Sikorski A.
  2. 9 Korzeniewski M.
  3. 8 Kulikowski K.
  4. 7 Ruszczyk A.
  5. 4 Polanowski P.
Więcej...
Lata help
  1. 1 2021
  2. 4 2020
  3. 1 2018
  4. 3 2017
  5. 4 2016
Więcej...
Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 64

Liczba wyników na stronie
first rewind previous Strona / 4 next fast forward last
Wyniki wyszukiwania
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 4 next fast forward last
1
Content available remote Computer Simulation of the Dynamic Behavior of Double Polymer Brush-Solvent Systems
Hałagan K., Banaszak M., Jung J., Polanowski P., Sikorski A.
Computational Methods in Science and Technology
|
2021
|
Vol. 27, No. 4
141--149
EN
Opposing polymer brush systems were investigated by computer simulations. In a coarse-grained model, chains were restricted to a face-centered cubic lattice with the excluded volume interactions only. The macromolecules were grafted onto two parallel impenetrable surfaces. The dynamic properties of these systems were studied by means of Monte Carlo simulations. The Dynamic Lattice Liquid model and a highly efficient parallel machine ARUZ were employed, which enabled studying large systems at long time scales. The influence of the surface grating density on the system dynamic was shown and discussed. It was demonstrated that the self-diffusion coefficient of solvent depended strongly on the grafting density.
2
Content available remote The influence of temperature on the percolation threshold in two-dimensional polymer systems
Sikorski A.
Computational Methods in Science and Technology
|
2020
|
Vol. 26, No. 4
143--149
EN
The structure of a two-dimensional film formed by strongly adsorbed polymer chains was studied by means of Monte Carlo simulations. We investigated the percolation in systems consisting of flexible polymer chains. A coarse-grained polymer chains representation was assumed and polymer chains were represented by linear sequences of lattice beads. The positions of these beads were restricted to vertices of a two-dimensional square lattice. Properties of the model system were determined by means of Monte Carlo simulations with a refined Verdier-Stockmayer sampling algorithm. Percolation thresholds macromolecules were determined. The methodology concerning the determination of the percolation thresholds for an infinite chain system was discussed. The influence of the chain length and the temperature on the percolation was discussed. It was shown that the introduction of long-range interactions changes the behavior of the percolation threshold dramatically. The percolation threshold initially decreases with the chain length while for longer ones it is stable.
3
Content available remote Technology of Real-World Analyzers (TAUR) and its practical application
Jung J., Kiełbik R., Hałagan K., Polanowski P., Sikorski A.
Computational Methods in Science and Technology
|
2020
|
Vol. 26, No. 3
69--75
EN
The article describes the most important details of the project for reconfigurable construction of dedicated electronic machines intended for performing analyses of phenomena that occur in multi-component systems containing at least several million mutually interacting elements. Devices built in the presented technology can be characterized by the use of reconfigurable integrated circuits, spatial construction ensuring scalability, a redundant panel system as well as specially developed data transmission and work control systems. Machines work in a parallel manner and can solve problems in various fields of science and technology by competing with the speed of data processing with the latest supercomputing systems. As an example, we present details of the ARUZ machine containing 26,000 FPGAs, which was made using this technology.
4
Content available Properties of active rectifier with LCL filter in the selection process of the weighting factors in finite control set-MPC
Falkowski P., Sikorski A., Kulikowski K., Korzeniewski M.
Bulletin of the Polish Academy of Sciences. Technical Sciences
|
2020
|
Vol. 68, nr 1
51--60
EN
One of the main problems of multivariable cost functions in model predictive control is the choice of weighting factors. Two finite control set model predictive control algorithms, applied to the three-phase active rectifier with an LCL filter, are described in the paper. The investigated algorithms, i.e. PCicuc and PCigicuc, implement multivariable approaches applying line (grid) current, capacitor voltage and converter current. The main problem dealt with in the paper is the choice of optimum values of the cost function weighting factors. The values of the factors calculated using the method proposed in the paper are very close to the values represented by the lowest THDi of the line current. Moreover, simulations verifying the equations used in the prediction of controlled values, i.e. line current, capacitor voltage and converter current, are presented. Both simulation and experimental results are presented to verify effectiveness of the investigated control strategies under change of the load (P = 5 kW and 2.5 kW), during transient states, under unbalanced and balanced line voltage.
5
Content available Predictive current control of three-phase matrix converter with GaN HEMT bidirectional switches
Nowaszewski K., Sikorski A.
Bulletin of the Polish Academy of Sciences. Technical Sciences
|
2020
|
Vol. 68, nr 5
1077--1085
EN
This paper presents an analysis and simulation studies of three-phase matrix converter with GaN HEMT bidirectional switches with predictive control of grid currents and converter output currents. Two methods of grid currents shaping are described and compared. The first method is based on calculations of instantaneous grid reactive power and the second one uses the active power of the load. The analyzed converter works with the resistive-inductive load, and from the grid side the LC filter with damping resistor has been used.
6
Content available remote From the Dynamic Lattice Liquid Algorithm to the Dedicated Parallel Computer – mDLL Machine
Jung J., Kiełbik R., Rudnicki K., Hałagan K., Polanowski P., Sikorski A.
Computational Methods in Science and Technology
|
2018
|
Vol. 24, No. 4
235--247
EN
The designing, production and testing of the mDLL machine led to the development of such a structure in which operational cells (e.g. KDLL) were located in the nodes of a three-dimensional torus network and the device was scalable. Thus, the future expansion of this device with additional Printed Circuit Boards (PCB) will not result in lengthened wire connections between Field-Programmable Gate Arrays (FPGA) or slow down the operation of the machine. The conducted tests confirmed the correctness of the adopted design assumptions and showed that by using mDLL one can effectively perform molecular simulations. Despite some structural shortcomings, the mDLL machine was a prototype that has already been sufficiently tested to allow the technology used in it to be used to build a device with a number of 1 million to 5 million KDLL cells. Such a device would already be suitable for simulating multi-particle systems with unprecedented speed.
7
Content available FACET5 in the recruitment and managing process as regards production personnel – case study
Sikorski A.
Production Engineering Archives
|
2017
|
Vol. 15
36--40
EN
The hereby article describes the study of two cases, the recruitment process as regards a newly created position and the decision concerning promotion to a managerial position. In both cases tool called Facet5 (used for measuring employees' potential) was applied to support decisions connected with human resources. As far as the first case is concerned, the profile of an ideal candidate was established. Then the profiles of three candidates selected based on content were compared to the aforementioned profile of an ideal candidate. As regards the second case, the analysis of the strengths and weaknesses in the employee profile and comparing the benchmarks concerning the particular position confirmed the subjective assessments of the supervisors and contributed to making the right decision. The issues connected to the increasing significance of soft competences, talent management in organization and organizational culture in terms of employee effectiveness and corporate competitive were discussed as well. Analyzed situations indicate the potential value resulting from the usage of tools for researching employees’ potential.
8
Content available Frequency based islanding detection methods in power electronic converters
Dmitruk K., Korzeniewski M., Sikorski A.
Power Electronics and Drives
|
2017
|
Vol. 2 (37), No. 1
27--41
EN
Frequency based methods developed to detect an islanding condition in modern power grid structures have been discussed. The condition may occur in power grid lines to which additional energy sources with power electronic converters have been connected such as solar panels or wind turbines. It is a hazardous operating state for grid workers and devices connected to the islanded part of the grid. Such a state results from the inability to control amplitude and frequency of basic harmonic of the grid voltage. An islanding problem in a power grid with additional small energy sources has been discussed. A basic passive and active islanding detection method have been presented and compared with known frequency based algorithms, namely active frequency drift and active frequency drift with a positive feedback algorithm. Finally, a laboratory test of the proposed islanding detection methods in a three-phase grid with an AC-DC converter has been conducted. To demonstrate differences between the tested methods, total harmonic distortion injected into the output converter current and detection time of islanding state have been measured.
9
Content available remote Monte-Carlo Simulations of Two-Dimensional Polymer Solutions with Explicit Solvent Treatment
Polanowski P., Jeszka J. K., Sikorski A.
Computational Methods in Science and Technology
|
2017
|
Vol. 23, No. 4
305--316
EN
The static properties of two dimensional athermal polymer solutions with explicit solvent molecules were studied by Monte Carlo lattice simulations using the cooperative motion algorithm (CMA). The simulations were performed for a wide range of polymer chain length N (from 16 to 1024) and polymer concentration (from 0.0156 to 1.00). The results obtained for short chains (N < 256) were in good agreement with theoretical predictions and previous simulations. For the longest chains (512 or 1024 beads) some unexpected behavior in the dilute and semidilute regimes was found. A rapid change in the concentration dependence of the end-to-end distance, the radius of gyration and the chain asphericity was observed below a critical concentration of the microphase separation, ϕc = 0.6 (for N = 1024). At concentrations lower than _c, the chains tends to be more rod-like. Single chain scattering structure factors showed changes in the fractal dimension of the chain as a function of the polymer concentration. The observed phenomena can be related to the excluded volume of solvent molecules, which leads to a modification of chain statistics in the vicinity of other chains.
10
Content available remote Predykcyjne sterowanie napięciem wejściowym prądowego przekształtnika AC/DC
Godlewska A., Sikorski A.
Przegląd Elektrotechniczny
|
2016
|
R. 92, nr 5
167--171
PL
Praca dotyczy sieciowego przekształtnika AC/DC pracującego jako źródło prądowe. Referat przedstawia nowy sposób sterowania przekształtnikiem, opierający się na predykcji napięcia wejściowego, który zapewnia jednostkowy współczynnik mocy i minimalizuje zawartość wyższych harmonicznych w prądzie pobieranym z sieci. Zaproponowana metoda opiera się na wyborze wektorów prądu prostownika w zależności od najmniejszej wartości współczynnika jakości. Poprawność działania algorytmu potwierdzają wyniki symulacji w środowisku MATLAB/Simulink.
EN
The paper presents a new control algorithm for Current Source Rectifier supplied from the grid, based on input voltage prediction. Proposed method corrects power factor and reduces higher harmonics in phase current. The algorithm chooses proper space vector of CSR according to the smallest value of the cost function. Properties of the new method are shown in simulations carried out using MATLAB/Simulink.
11
Technologia przęsło po przęśle na przykładzie mostu w ciągu DTŚ w Gliwicach
Salamak M., Klikowicz P., Sikorski A.
Mosty
|
2016
|
nr 4
28--31
PL
Artykuł prezentuje najdłuższy obiekt mostowy, jaki wykonano w ramach budowy ostatniego odcinka Drogowej Trasy Średnicowej w Gliwicach. Szczegółowo opisano konstrukcję tego mostu i zastosowaną technologię przęsło po przęśle z urządzeniem formującym przejezdnym po terenie. Pokazano specyfikę układu sprężenia tego typu obiektów oraz podział procesu realizacji na etapy z przyjętym 14-dniowym cyklem.
EN
The article presents the longest bridge which has been constructed within the completion of the last section of the DTŚ central highway in Gliwice. It describes in detail the construction of the bridge and the span-by-span technology used with the forming device running on the ground. The specificity of prestressing layout of this type of structures, as well as the division of the construction process into stages with the accepted 14-day cycle have been presented.
12
Content available remote The Comparison of Monte Carlo Algorithms Applied for Off-Lattice Models of Polymer Chains
Kuriata A., Gront D., Sikorski A.
Computational Methods in Science and Technology
|
2016
|
Vol. 22, No. 4
179--185
EN
We designed two simplified models of macromolecular systems. Model chains were built of united atoms (statistical segments): the first one was a bead-spring model while in the second one beads were connected by bonds of constant length. The only potential introduced was the excluded volume and thus the system was athermal. Monte Carlo simulations of these models were carried out using Metropolis-like algorithms appropriate for each model: the one-bead displacement and the backrub algorithm. The scaling analysis of the chain’s static and dynamic properties was carried out. The universal behavior of the chain’s properties under consideration was found and discussed. The efficiency of both algorithms was compared and discussed.
13
Content available Integracja oprogramowania klasy Open BIM w inżynierii projektów budowlanych
Wiatr T., Sikorski A.
Biuletyn Wojskowej Akademii Technicznej
|
2016
|
Vol. 65, nr 4
178--192
PL
Klasyczne zarządzanie projektami w budownictwie oparte jest na wielu wyspecjalizowanych aplikacjach komputerowych, które w nikłym zakresie wymieniają między sobą dane. Metodyka BIM (Building Information Modelling) umożliwia współpracę i wymianę danych — w szczególności w oparciu o format IFC (Industrial Foundation Classes) — obejmując projektowanie budowlane w CAD i FEM oraz planowanie budowy z użyciem PMS. Integracja BIM napotyka na ograniczenia metodyczne i biznesowe. Ograniczenia biznesowe to duże koszty oprogramowania niezbędne do poniesienia w celu wykonania analizy kompleksowej. Problemy te pozwala pokonać Open BIM i koncepcja autorów oparta na dekompozycji obiektu budowlanego i selektywnym przetwarzaniu danych, możliwa do uzyskania dzięki powiązaniu wiedzy o projektowaniu budynków i procesów ich budowy. Artykuł zawiera przegląd systemów i opis koncepcji w kontekście polskiego budownictwa.
EN
The conventional approach to project management in construction industry is based on multiple specialized software tools which have very limited capability of data exchange. The BIM methodology allows for co-operation and data transfers among various member subsystems relying on IFC which supports construction designing with CAD, FEM, and construction planning using PMS. The most challenging obstacles to full integration are of two kinds: methodological and business related. The business-related problems result from high costs of a complete analysis and software tools. These challenges can be overcome with Open BIM, an approach proposed by the authors, which is based on the model decomposition and independent processing resulting from combination of the design and management processes awareness of the building features. This survey includes both proposed systems and the underlying concepts in Polish construction context.
14
Content available remote Computer Simulation of Cyclic Polymers in Disordered Media
Kuriata A., Sikorski A.
Computational Methods in Science and Technology
|
2015
|
Vol. 21, No. 1
21--27
EN
In order to determine the structure and dynamical properties of cyclic polymers (rings) in a random environment we developed and studied an idealized model. All atomic details were suppressed, chains were represented as a sequence of identical beads and were embedded to a simple cubic lattice. A set of obstacles was also randomly introduced into the system and it can be viewed as a model of porous media. A Monte Carlo sampling algorithm using local changes of chain conformation was used to sample the conformational space. It was shown that the mean dimensions of the chain changed with the concentration of obstacles but these changes were non-monotonic. The long-time (diffusion) dynamic properties of the system were also studied. The differences in the mobility of chains depending on the obstacle density were shown and discussed.
15
Content available remote Nowa metoda sterowania trójfazowym przekształtnikiem AC/DC
Godlewska A., Sikorski A.
Przegląd Elektrotechniczny
|
2014
|
R. 90, nr 11
70--73
PL
Praca dotyczy sieciowego przekształtnika AC/DC pracującego jako źródło prądowe. Referat przedstawia nowy sposób sterowania przekształtnikiem, bazujący na metodzie DPC, który zapewnia jednostkowy współczynnik mocy i minimalizuje zawartość wyższych harmonicznych w prądzie pobieranym z sieci. Zaproponowana metoda opiera się na zasadzie wyboru wektorów prądu prostownika w zależności od zadanej wartości prądu stałego i prądu pobieranego przez filtr pojemnościowy. Poprawność działania algorytmu potwierdzają wyniki symulacji w środowisku MATLAB/Simulink.
EN
The paper presents a new control algorithm for Current Source Rectifier supplied from the grid, based on Direct Power Control. Proposed method corrects power factor and reduces higher harmonics in phase current. The algorithm chooses proper space vector of CSR according to the reference direct current and filter current. Properties of the new method are shown in simulations carried out using MATLAB/Simulink.
16
Content available remote Wpływ parametrów maszyny indukcyjnej na predykcyjną regulację momentu i strumienia
Falkowski P., Sikorski A.
Przegląd Elektrotechniczny
|
2013
|
R. 89, nr 9
19-22
PL
W artykule wyznaczono zależności umożliwiające predykcyjne sterowanie momentu i strumienia silnika indukcyjnego zasilanego z przekształtnika DC/AC. Zaproponowano sposób wyznaczania funkcji kosztów Jk określającej warunki predykcji. Przedstawiono wyniki badań symulacyjnych, obrazujących wpływ współczynnika wagowego wPSI (wykorzystywanego w funkcji kosztów Jk) na wielkości takie jak: średnie wartości momentu Ms(av) i strumienia Ψs(av), współczynnik odkształcenia momentu ΔM(RMS) i strumienia ΔΨ(RMS), oraz średnią częstotliwość przełączeń fs(av).W artykule wyznaczono zależności umożliwiające predykcyjne sterowanie momentu i strumienia silnika indukcyjnego zasilanego z przekształtnika DC/AC. Zaproponowano sposób wyznaczania funkcji kosztów Jk określającej warunki predykcji. Przedstawiono wyniki badań symulacyjnych, obrazujących wpływ współczynnika wagowego wPSI (wykorzystywanego w funkcji kosztów Jk) na wielkości takie jak: średnie wartości momentu Ms(av) i strumienia Ψs(av), współczynnik odkształcenia momentu ΔM(RMS) i strumienia ΔΨ(RMS), oraz średnią częstotliwość przełączeń fs(av).
EN
In the article relationships enabling a torque and flux predictive control of the induction motor fed by DC/AC inverter were calculated. The solution of a cost function Jk calculation characterizing prediction conditions was proposed. The results of simulations illustrating the influence of the weighting factor wPSI (used in cost function Jk) on quantities such as average value of the torque and flux, coefficients of the torque and flux distortions, average switching frequency were shown.
17
Content available remote Predykcyjna regulacja mocy czynnej przekształtnika AC/DC ze stałą średnią częstotliwością przełączeń
Falkowski P., Sikorski A.
Przegląd Elektrotechniczny
|
2013
|
R. 89, nr 12
53-56
PL
W artykule omówiono zasadę działania predykcyjnej regulacji mocy czynnej opartej o model przekształtnika AC/DC. Zaproponowano wskaźnik kosztów Jk2, rozbudowany o dodatkowy współczynnik wagowy wx, który umożliwia utrzymywanie stałej średniej częstotliwości przełączeń fs(av). Przedstawiono wyniki badań symulacyjnych obrazujących, wpływ współczynnika wagowego wx na utrzymywanie zadanej średniej wartości częstotliwości przełączeń fs(av) *.
EN
In the article discussed the principle of predictive control of active power converter based on the model of AC/DC converter. A cost function Jk2 expanded by an additional weighting factor wx which enable to maintain a constant average switching frequency fs(av) was proposed. The results of simulations illustrating the influence of the weighting factor wx to maintain the set average switching frequency fs(av) * where shown.
18
Content available remote Percolation in Systems Containing Ordered Elongated Objects
Romiszowski P., Sikorski A.
Computational Methods in Science and Technology
|
2013
|
Vol. 19, No. 2
115--121
EN
We studied the percolation and jamming of elongated objects using the Random Sequential Adsorption (RSA) technique. The objects were represented by linear sequences of beads forming needles. The positions of the beads were restricted to vertices of two-dimensional square lattice. The external field that imposed ordering of the objects was introduced into the model. The percolation and the jamming thresholds were determined for all systems under consideration. The influence of the chain length and the ordering on both thresholds was calculated and discussed. It was shown that for a strongly ordered system containing needles the ratio of percolation and jamming thresholds cp=cj is almost independent on the needle length d.
19
Content available Modern Direct Torque and Flux Control methods of an induction machine supplied by three-level inverter
Sikorski A., Kulikowski K., Korzeniewski M.
Bulletin of the Polish Academy of Sciences. Technical Sciences
|
2013
|
Vol. 61, nr 4
771--778
EN
This paper describes two modern direct torque and flux control methods of an induction machine supplied by a three-level inverter. Additionally, it presents a comparison of the methods both in static and dynamic states. The methods, in a specific way, make use of an increased number of active vectors of the three-level inverter in order to improve control quality and reduce switching frequency. The two methods modify the DTC method by using its advantages and eliminating, at the same time its drawbacks. In static states the comparison was based on the results of investigations performed for two different load values and three set values of angular speed, whereas in dynamic states the comparison was focused on the behavior of the machine at startup. The results of the investigations have shown that both methods give very good performance. They are characterized by both sinusoidal shape of flux and low current deformations even at low angular speeds i.e. less than 10% of the nominal value. The presented methods also allow to generate nominal flux for set zero angular speed in order to achieve excitation of the induction machine. The switching frequencies for both methods are very similar in almost the whole range of control but the methods have shown some differences in control quality, particularly for higher torque values.
20
Content available remote Wybrane problemy współpracy małej elektrowni wodnej z przekształtnikiem AC/DC/AC
Korzeniewski M., Sikorski A.
Przegląd Elektrotechniczny
|
2012
|
R. 88, nr 4b
128-133
PL
W artykule przedstawiono wybrane problemy dotyczące współpracy przekształtnika AC/DC/AC z generatorem asynchronicznym małej mocy zainstalowanym w elektrowni wodnej. Generator asynchroniczny w połączeniu z przekształtnikiem energoelektronicznym umożliwia oddawanie energii do sieci energetycznej lub na wydzieloną grupę odbiorników nawet przy niskich prędkościach turbiny. W artykule przedstawiono wyniki badań generatora i przekształtnika AC/DC/AC w stanach ustalonych, przejściowych oraz podczas rozruchu w przypadku braku napięcia sieci.
EN
The article discusses application of AC/DC/AC converter cooperating with an asynchronous generator in small hydroelectric power plants. The asynchronous generator works with power grid or a separated group of receivers, enabling to generate power even at low speeds of the turbine. The article provides also results of the investigation concerning the functioning of the generator coupled with AC/DC/AC converter in steady and transient states during start-up and voltage decay.
first rewind previous Strona / 4 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.