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1
Content available remote Optymalizacja parametrów pracy siłowni osiągającej zaawansowane super ultranadkrytyczne parametry pary świeżej oraz modyfikacje obiegu parowego pozwalające zwiększyć jego sprawność
Głuch S., Piwowarski M.
Instal
|
2018
|
nr 10
8--10
PL
W niniejszym artykule przedstawiono metody optymalizacji parametrów siłowni osiągającej zaawansowane super ultranadkrytyczne parametry pary. Stworzono modele obliczeniowe trzech nadkrytycznych obiegów parowych: z pojedynczym przegrzewem międzystopniowym, z podwójnym przegrzewem międzystopniowym oraz „Master Cycle”. Zaprezentowano wpływ dodatkowego przegrzewu międzystopniowego i konfiguracji Master Cycle na sprawność obiegu parowego. Przedstawiono wpływ temperatury wody zasilającej, oraz ciśnień podziałowych na sprawność. Obliczenia pokazują, że możliwe jest przekroczenie progu 50% sprawności netto elektrowni parowej.
EN
This paper presents methods of optimisation of steam cycles. A computational model of three supercritical cycles have been created: with singular interstage steam superheat, double interstage steam superheat and Master cycle. Impact of additional steam superheat and Master cycle on efficiency have been presented. Effect of feedwater temperature and division pressure on efficiency have been shown. The calculations show that it is possible to exceed 50% net efficiency of steam power plant.
2
Content available Design and investigations of the ethanol microturbine
Kosowski K., Piwowarski M., Stępień R., Włodarski W.
Archives of Thermodynamics
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2018
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Vol. 39, no 2
41--54
EN
The paper presents the results of the design analysis and experimental investigations of the microturbine set consisting of the microturbine with partial admission and permanent magnet generator. The microturbine was designed for operation with the vapour of ethanol as a working fluid. Microturbine unit was tested for different parameters of the working fluid and varying the electrical load. The examples and the comparison between experiment results and numerical simulations are shown and discussed in the paper.
3
Content available Possibilities of Increasing the Overall Efficiency of Gas-Steam CHP Microplant
Piwowarski M., Kwaśniewski T.
Acta Energetica
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2018
|
nr 2
81--86
EN
The paper presents ways to increase the efficiency of a gas-steam micro power plant by modifying the cycle combination. The modification consists in partial release of the fluid downstream of the gas turbine and using it for ORC fluid overheating and evaporation. Advantages of this solution over the simplest gas and steam cycles’ combination are demonstrated.
PL
W artykule przedstawiono sposoby zwiększenia sprawności mikrosiłowni gazowo-parowej poprzez modyfikację sposobu powią- zania obiegów. Modyfikacja polega na zastosowaniu upustu części czynnika zza turbiny gazowej i wykorzystaniu go do przegrzania oraz odparowania czynnika ORC. Wykazano przewagi tego rozwiązania nad najprostszym sposobem powiązania obiegu gazowego z parowym.
4
Analiza obiegów kogeneracyjnych z silnikami tłokowymi i mikroturbinami
Cieśliński A., Kosowski K., Piwowarski M., Stępień R., Włodarski W.
Rynek Energii
|
2015
|
Nr 6
41--46
PL
Przeprowadzono analizę dla układów kogeneracyjnych z mikroturbinami wykorzystującymi ciepło odpadowe z silników tłokowych. Rozważono cztery główne źródła ciepła odpadowego z silników tłokowych: spaliny wylotowe, woda chłodząca silnik, olej smarny i ciepło z systemu turbodaładowania. Obliczenia przeprowadzono dla silników General Electric Jerbacher typów: J320 GS-C25 i J416 GS-B05. Uwzględniono różne czynniki robocze siłowni (zarówno “suche”, jak i “mokre”) oraz różne cycle termodynamiczne. Nasze badanie wykazały, że wykorzystując ciepło odpadowe silników, można nie tylko podgrzewać wodę, ale także wytwarzać energię elektryczną. W ten sposób można podnieść sprawność ogólną wytwarzania energii elektrycznej nawet o 20%.
EN
The analysis was carried out for Combined Heat and Power generation systems with micro-turbines power plants working on heat rejected from the reciprocating engine. There are four main sources of heat rejected from the stroke engines: exhaust gases, engine cooling water, lubricating oil and intercooler. The calculations were performed for GE Jerbacher engines of J320 GS-C25 and J416 GS-B05 types. We considered different working media (both wet and dry fluids) and different thermodynamic cycles. Our results proved that using the heat rejected from the engines is possible not only to warm up water but also to produce some electric power and, in this way, increase the total electric output by even 20%.
5
Content available Design analysis of ORC micro-turbines making use of thermal energy of oceans
Piwowarski M.
Polish Maritime Research
|
2013
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nr 2
48--60
EN
The article presents the results of the analysis of energy conversion cycles making use of thermal energy of oceans. The objects of analysis were two cases of closed Organic Rankine Cycle (ORC) power plants, which were: the cycle in which the vapour of the working medium was produced by warm oceanic water in the circum-equatorial zone, and the so-called “arctic” cycle in which this vapour was produced by non-frozen water in the circumpolar zone. Between ten and twenty low-boiling media were examined for which operating parameters were optimised to obtain the highest cycle efficiency. A preliminary design of an ORC turbine which was obtained by optimising basic design parameters is included. It has been proved that realisation of the Ocean Thermal Energy Conversion (OTEC) cycle is possible both in the warm and permanently frozen regions. The results of the calculations have also revealed that the efficiency of the OTEC cycle is higher in the circumpolar zone. Selecting a low-boiling medium and designing a highly efficient turbine operating in both abovementioned regimes is technically realisable.
6
Content available remote Modelowanie preferencji użytkowników w serwisach zintegrowanych z Google Maps
Piwowarski M., Bochan S., Nermend K.
Zeszyty Naukowe. Studia Informatica / Uniwersytet Szczeciński
|
2012
|
Nr 31
185--199
PL
W artykule poruszono problematykę modelowania preferencji użytkowników w serwisach internetowych. Przybliżone zostały podstawowe pojęcia i rozwiązania wykorzystywane w serwisach internetowych zintegrowanych z Google Maps. Rozważania teoretyczne zostały wzbogacone opisem zrealizowanego projektu i uzyskanych wyników (wizualizacji), uwzględniających indywidualne preferencje użytkownika.
EN
This paper addresses the problem of modeling user preferences in web sites. Approximate were the basic concepts and solutions used in websites integrated with Google Maps. Theoretical considerations are enhanced description of the project and the results obtained (visual), taking into account individual preferences.
7
Content available remote Metoda personalizacji treści w serwisach internetowych
Piwowarski M., Szczyciński K., Nermend K.
Zeszyty Naukowe. Studia Informatica / Uniwersytet Szczeciński
|
2012
|
Nr 31
201--215
PL
Głównym celem artykułu jest zaprezentowanie autorskiej metody personalizacji zawartości serwisu internetowego. Pierwsza część publikacji zawiera krótki przegląd istniejących metod personalizacji treści w witrynach. W dalszej części znajduje się opis opracowanej metody personalizacji (połączenie metody MinHash w podejściu generowania rekomendacji opartym na podobieństwie użytkowników typu przedmiot–przedmiot oraz metody AHP), a następnie przedstawiane są wyniki badań symulacyjnych dla wybranego zestawu danych.
EN
The main purpose of this article is to present a content personalization method in the website. The document is divided into three chapters. The first chapter describes the analysis of existing content personalization methods in websites. The next part contains the description of created author’s method (a combination of methods MinHash and AHP) with description of implementation. The last chapter it presents test results for used dataset.
8
Content available Analiza czynników niskotemperaturowych do instalacji grzewczej w jednorodzinnym budynku mieszkalnym
Lenz M., Piwowarski M., Stępień R., Wiśniewski D., Hałacz J.
Biuletyn Wojskowej Akademii Technicznej
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2012
|
Vol. 61, nr 2
331-345
PL
W niniejszej pracy przeprowadzono analizę projektową instalacji grzewczej opartej na sprężarkowej pompie ciepła. Instalacja ta zasila systemy centralnego ogrzewania i przygotowania ciepłej wody użytkowej w jednorodzinnym budynku mieszkalnym znajdującym się w miejscowości Koleczkowo. W analizie zawarto ocenę strat i zysków cieplnych budynku, obliczenia zapotrzebowania na moc cieplną analizowanego obiektu oraz koncepcyjne rozwiązania instalacji grzewczej. Zaproponowano wariant optymalny ze względu na maksymalną sprawność, do którego dobrane zostały jego główne elementy. Przeanalizowano wpływ grupy wybranych czynników chłodniczych na sprawność oraz parametry pracy zaproponowanej pompy ciepła.
EN
This study involves a design analysis of the heating system based on a compression heat pump. This installation supplies central heating and tap water heating systems in a detached residential building situated in Koleczkowo. The analysis includes an assessment of heat loss and gain of the building, calculations of the demand for the heating power of the building under analysis and conceptual solutions concerning the heating system. The optimal variant was proposed with regard to its maximum efficiency, for which the main elements were chosen. The effects of the set of selected cooling factors on the efficiency and operating parameters of the proposed heat pump are also analysed.
9
Content available remote Procedure of reducing website assessment criteria and user preference analyses
Ziemba P., Piwowarski M.
Foundations of Computing and Decision Sciences
|
2011
|
Vol. 36, No. 3-4
315-325
EN
The article outlines the issues of website quality assessment, reduction of website assessment criteria and factors that users employ in the assessment of websites. The article presents a selection procedure concerning significant choice criteria and revealing undisclosed user preferences based on news portals and the eQual assessment model. The formulated procedure utilizes statistical metrics, multiple criteria decision making, rough sets and data mining tools. Results concerning undisclosed preferences were verified through a comparison to those declared by website users. The obtained results were further verified through a comparison of website assessments obtained via a full and reduced set of website assessment criteria.
10
Dobór platformy e-learningowej za pomocą metody Promethee GDSS
Ziemba P., Piwowarski M.
Metody Informatyki Stosowanej
|
2010
|
nr 4 (24)
109-124
EN
In the article four most popular e-learning platforms spread on OpenSource principles were characterised. These systems were subjected to the evaluation of the experts group using the Promethee GDSS method. Assumptions of this method were presented in contents of the article besides guidelines of Promethee procedures II and GAlA, which procedures are using GDSS method. In the end conducted examinations were get ranking of e-learning platforms. This ranking was formed by the group of experts. In the obtained solution appearing of conflicts be twe en experts was examined. Next it stayed modified with using sensitivity analyses.
11
Content available Optimization of steam cycles with respect to supercritical parameters
Piwowarski M.
Polish Maritime Research
|
2009
|
S 1
45-51
EN
This paper contains an analysis of supercritical power stations have been presently built worldwide. The analysis concerns cycles with single and double interstage superheating and, additionally, with regenerative feed water preheating system equipped with six, seven, eight, nine and ten regenerative heat exchangers, respectively. Relevant calculations were performed for various values of fresh steam temperature and pressure, various pressure values of secondary superheating, as well as with value of condenser internal pressure maintained constant. The calculations show that to increase efficiency of steam cycle with double interstage superheating and extended regeneration even to a value greater than 51%, is possible. In the age of greater and greater demand for electric power and stronger and stronger limitations imposed on emission of noxious compounds to the atmosphere, the developing of power production technologies based on supercritical parameters seems inevitable.
12
Content available Evaluation of technical efficiency of heat and electric power generation
Piwowarska H., Piwowarski M.
Polish Maritime Research
|
2009
|
S 1
39-44
EN
This paper presents an evaluation of technical efficiency and time-dependent changes in productivity of Polish professional electric power and heat & electric power stations by using Data Envelopment Analysis non-parametric method. The research covered the enterprises whose total available electric power amounted to about 98% of that of all professional thermal electric power stations in this country. The analysis has concerned the years 2000÷2004. Impact was considered of such factors as: scale of enterprise activity, form of ownership as well as type of carried out activity, on technical efficiency and time-dependent productivity changes. Changes in productivity of the power generation sector were determined by means of Malmquist index.
13
Content available Design analysis of turbines for co-generating micro-power plant working in accordance with organic Rankine’s cycle
Mikielewicz J., Piwowarski M., Kosowski K.
Polish Maritime Research
|
2009
|
S 1
34-38
EN
This paper presents results of a design analysis of turbines for co-generating micro-power plant working in accordance with organic Rankine’s cycle and using biofuel. The heat power range from 25 kW to 100 kW with corresponding available electric power from 2kW to 12kW, was considered. Designs of axial-flow turbines (single-stage and multi-stage ones, also those partially fed), radial-flow and axial-radial -flow ones, were analyzed. Particular variants of the solutions were compared to each other.
14
Content available Design analysis of Tesla micro-turbine operating on a low-boiling medium
Lampart P., Kosowski K., Piwowarski M., Jędrzejewski Ł.
Polish Maritime Research
|
2009
|
S 1
28-33
EN
This paper presents results of the design analysis of a Tesla bladeless turbine intended for a co-generating micro-power plant of heat capacity 20 kW, which operates in an organic Rankine cycle on a low-boiling medium. Numerical calculations of flow in several Tesla turbine models were performed for a range of design parameters. Results of investigations exhibit interesting features in the distribution of flow parameters within the turbine interdisk space. The calculated flow efficiency of the investigated Tesla turbine models show that the best obtained solutions can be competitive as compared with classical small bladed turbines.
15
Metody analizy wielokryterialnej we wspomaganiu porównania produktów w Internecie
Ziemba P., Piwowarski M.
Metody Informatyki Stosowanej
|
2008
|
nr 2 (Tom 15)
137-147
PL
Celem niniejszego artykułu jest dokonanie przeglądu funkcjonalności istniejących serwisów porównawczych na polskim rynku oraz wskazanie możliwości ich rozwoju. Proponowane rozwiązanie obejmuje zwiększenie liczby kryteriów porównywania produktów oraz zaadoptowania metod wielokryterialnej analizy decyzyjnej do uzyskania najlepszych wariantów decyzyjnych z punktu widzenia użytkownika serwisu.
EN
The following paper is dealing with directions developing in the literature on choosing the MCDA method best suited to solve a given decision problem. When considering factors originating from the subject of the decision, the main focus was on case studies which support applying a particular method to a given problem - price comparison in the Internet.
16
MCDA model approach to the Business Process Modeling methods evaluation
Szarafińska M., Konys A., Piwowarski M.
Metody Informatyki Stosowanej
|
2008
|
nr 3 (Tom 16)
237--246
EN
The purpose of this paper is a recapitulation of research conducted hitherto on the evaluation of business process modeling methods and techniques. Due to the systemizing the recognized knowledge of existing modeling method it is necessary to identify the information that allow further specification. Multitude of available solutions as well as wide applicable area indicates that the synthesis of current state condition is being required as well. This paper present comparative analysis which has been processed at use of the modeling concept which is based on proposes of levels of abstraction. Furthermore the results of presented estimates have been transformed into a Multi Criteria Decision-Making process and explore for further research using the AHP method implementation. The methodology used in this paper refers to criteria of business process modeling method. Finally based on the conducted research, conclusion and direction for further research ends the study.
17
Algorytm doboru metod wielokryterialnych do zadanej sytuacji decyzyjnej
Piotrowski Z., Wątróbski J., Piwowarski M.
Metody Informatyki Stosowanej
|
2008
|
nr spec. (Tom 14)
223-234
EN
Each decision situation is described by a set of distinguishing characterises a factor which classifies it into a category of decision problems. Many times the chosen category determines the choice of the most suitable MCDA method to apply for supporting a decision maker. The following paper is dealing with directions developing in the literature on choosing the MCDA method best suited to solve a given decision problem. In the study, two sources of factors which influence the choice of the method were identified: a subject of the decision and a characteristic of dependencies in the problem, description. When considering factors originating from the subject of the decision, the main focus was on case studies which support applying a particular method to a given problem. Dependencies between parameters describing a problem were analysed from the impact that the existence of various data sources has on them. The selected group of factors was consecutively generalised and its impact on the result of the decision support using a collection of methods pointed out. The performed analysis constitutes a source of the strategy for choosing one method from the considered group of methods.
18
Content available remote Propagation of temperature waves in rigid conductors with a plain periodic structure
Piwowarski M.
Vibrations in Physical Systems
|
2004
|
Vol. 21
307--310
19
Impact of sea wave stochastic characteristics on ship propulsion control system design
Domachowski Z., Próchnicki W., Dzida M., Piwowarski M.
Marine Technology Transactions. Technika Morska
|
2004
|
Vol. 15
393-409
EN
A sea wave resistance to the ship motion is of stochastic nature. Therefore any design and optimization of ship propulsion control system requires a knowledge of wave resistance stochastic characteristics. Sea waving is usually considered as the most important disturbance affecting the dynamics of ship propulsion unit. In rough sea conditions it causes high amplitudes of torsional torques which lead to torsional vibrations of the elements of propulsion system. Limitation of tordional stresses is vitally important in order to avoid damage or even fracture of the propulsion system components. Torsional stresses involve the whole shaft system of the ship's propulsion engineering: engine crank shaft, intermediate shafts, propeller and propeller shaft, engine running gear, flywheel, and where appropriate reduction gearing, flexible couplings, clutches, and electric generator shaft. For a cost effective ship propulsion plant with the best counter measures against torsional stresses, it is important that torsional vibration aspects areconsidered at the earliest stage possible in the ship design process. In such circumstances the role of propulsion plant controller can be significant. With regard to sea wave stochastic characteristics a method of design and optimization of ship propulsion controller architecture and parameters has been discussed. Several simulations have been carried out based on sea wave stochastic characteristics. Some different sea areas in the world have been taken into account, and four seasons of year. The ship propulsion system bas been treated as a multidimensional control system of angular velocity od diesel engine. The dynamic processes of the propulsion system have been determined as a response to the disturbance caused by the ship propeller.
PL
Siła oporu statku jest procesem stochastycznym. Z tego powodu projektowanie i ewentualna optymalizacja układu sterowania napędu statku wymaga znajomości charakterystyk statycznych fali morskiej. Oddziaływanie zakłócające fali morskiej wywołuje, między innymi, zmiany momentów skręcających w elementach zespołu napędowego statku. Jest niezbędne ograniczenie momentów skręcających i wywołanych nimi drgań skrętnych, w celu uniknięcia ewentualnych uszkodzeń w zespole napędowym. Naprężenia skrętne występują w całym zespole napędowym statku: w walw silnika, wałach pośrednich, w wale pędnika, w sprzęgłach, przekładni. W tych warunkach dobór parametrów regulatora napędu statku umoże okazać się istotny. Wskazano sposoby doboru transmisji regulatora w warunkach stochastycznych. Wybrano do rozważań 8 rejonów morskich w 4 porach roku. Określono w nich gęstość widmową amplitudy fali morskiej. Założono, regulator typu proporcjonalno-całkująco-różniczkujący. Dla wybranego typu statku wykonane badania symulacyjne odnoszą się do wybranych rejonów mórz i pór roku. Okazuje się, że dobierając zarówno współczynnik wzmocnienia regulatora jak i stałą całkowania, można minimalizować wartość wariancji, na przykład, momentów skręcających w wybranych przekrojach zespołu napędowego lub prędkości kątowych wału. Przedstawiono przykłady tego rodzaju optymalizacji regulatora ze wzgledu na współczynnik wzmocnienia.
20
Application of neural networks for turbine rotor trajectory investigation
Pilarczyk B., Piwowarski M.
Marine Technology Transactions. Technika Morska
|
2004
|
Vol. 15
383-391
EN
Investigation of rotor systems ' vibration allows to monitor the technical condition continuosly and also to conduct diagnosing in failure cases. Vibration processes derive from the forces generated during the machine operation and they depend on, among others, on the change in eccentricity, axial clearance, rotor skew position as well as on the change in the shaft revolution frequency. The research aimed to check if application of neural networks enables it to determine the turbine rotor trajectory. A model single-stage air turbine was tested. measurements of horizontal and vertical displacements of the turbine rotor were taken by a measurement system and they were also recorded by a digital ascilloscope. Rotor motion trajectories were measured in different operating conditions considering the changes in eccentricity, axial clearance, rotor axis skewing with respect to the casing axis as well as in the rotor revolution frequency. Having obtained a lot of experimental data, an attempt was made to create a neural network determining the rotor trajectory for the pre-set operating conditions. A number of analyses of the rotor trajectories were conducted using variety of neural network initiation functions. Networks with unidirectional data transmission and the regressive propagation of error, with the cascade data transmission and the regressive propagation of error, as well as a regressive network were used. The obtained findings proved that the network is a good tool of forecasting of the rotor trajectory for variable turbine operational parameters. Exemplary calculations and their verification are given in the paper, too.
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