Wyniki wyszukiwania - Biblioteka Nauki

1

Modeling Gas Prices in Poland with an Application of the Vector Autoregression Method (VAR)

100%

Mentel G.

Folia Oeconomica Stetinensia

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2012

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tom 12

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nr 2

46-57

EN

The paper presents examples of gas prices modeling in Poland by means of the VAR model (AutoRegression Vector Model). For comparison, the predictions are made for the models estimated by different variations of the generalized least squares method. The analysis is based on gas prices set by the Carpathian Gas Company after 2000 for the tariffs applied for individual customers. Thus, value forecasts were presented for this type of energy for the “ordinary” customers in the light of the existing regulations.

2

Eficient multimode mixed time-frequency domain analysis and optimization of waveguide structures

100%

Kręczkowski A. , Mrozowski M.

Kwartalnik Elektroniki i Telekomunikacji

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2004

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tom Vol. 50, z. 4

653-661

EN

Application of full-wave analysis and optimization method of waveguide structures having a desired topology is presented. Modeling of waveguide discontinuities by generalized scattering matrices are efficiently performed utilizing the modified FDTD-IBC method. Numerical optimization and model measurements of the 7-th order waveguide direct coupled cavity filter validate the presented approach.

3

Modeling of direct and inverse problems in light scattering by rough surfaces

100%

Łukianowicz C.

Optica Applicata

|

2003

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tom Vol. 33, nr 2-3

329-336

EN

The rough surface assessment by light scattering methods is mostly preceded by the solution to the so-called direct and inverse problem. It requires assuming the mutual theoretical model, describing the phenomenon of light scattering by rough surfaces, for both problems. In general, despite application of numerous simplifications, it is an intricate diffraction model. The description of the rough surface geometry is also quite often complicated. Therefore, in many cases experimental verification of analytical solutions to the direct and inverse problems is very difficult. Under such circumstances it is advisable to verify the correctness of the solutions obtained using the computer-modeling methods. The paper presents the process of the direct and inverse problem modeling and covers the results of the model tests on selected surfaces

4

Modelowanie charakterystyk przyczepności ogumienia samochodów ciężarowych

85%

Luty W. , Prochowski L.

Zeszyty Instytutu Pojazdów / Politechnika Warszawska

|

2002

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tom z. 1/44

37-47

PL

W pracy przedstawiono wyniki badań eksperymentalnych ogumienia do samochodu ciężarowego średniej ładowności. Badaniom poddano trzy typy opon: 9.00R20 z kordem poliamidowo-stalowym oraz tzw. całostalowe o rozmiarze 9.00R20 i 255/70R22.5. Przedstawiono przebiegi charakterystyk przyczepności obwodowej w funkcji poślizgu wzdłużnego koła. Na podstawie eksperymentalnie wyznaczonych charakterystyk określono wartości współczynników do dwóch modeli współpracy koła ogumionego z podłożem: model Dugoffa oraz "magis formula" Pacejki. Wskazano na zależność charakterystyk przyczepności opon i wartości współczynników ich modeli od zastosowanego kordu w oponie, wartości obciążenia normalnego oraz prędkości toczenia koła.

EN

Experimental research results of truck tires are presented in this paper. Three types of tires were teted: 9.00R20 with cord of nylon and steel, all-steel tires 9.00R20 and 255/70R22.5. Characteristics of grip due to longitudinal slip are presented. Basing on acquired characteristics, values of two models coefficients were evaluated: Dugoff`s model and "magic formula" Pacejka`s model. A dependence of grip characteristics and values of their coefficients due to tire cord material, normal load value and rolling velocity are shown.

5

Spatial and statistical analysis in the design and monitoring of the engineering objects using DTM

85%

Bojarowski K.

Reports on Geodesy

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2005

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tom z. 3/74

19-26

6

Assessment of potential transport of transport company for random demand for transport services

80%

Konopacki G.

Research in Logistics & Production

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2014

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tom Vol. 4, No. 4

283--291

EN

Will be considered transport company exploiting the uniform in the sense of destination, means of transport such as tankers, with a total transport potential equal to a loading units (e.g. tones). The company operates in the transport market, where demand for transport services is random. Formulate the problem of satisfying the transport demand in full by transport company and shall be given the formulas to calculating the probability of such an event with the general assumptions about the demand for transport services. Practically useful formulas for estimating such a probability is given for the demand for transport services the described by normal stationary stochastic process. The results are illustrated by an example of the calculation.

7

Modelling of material behaviour for Inconel 718 superalloy using experimental data

80%

Nieslony P. , Grzesik W. , Laskowski P.

Journal of Machine Engineering

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2017

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tom Vol. 17, No. 3

75--84

EN

In this paper parameters of the Johnson-Cook (J-C) constitutive material model were predicted more accurately based on the static and dynamic material tests and mathematical modelling of relevant response surfaces using specially developed Matlab scripts. Experimental tests were performed under strain rates of 10-3 and 101 1/s and the temperature ranging from the ambient up to 700°C. As a result, a set of mathematical models which fit the experimental data was determined. The experimentally-derived constitutive models were implemented into FEM-based simulations of real machining processes of Inconel 718.

8

Modeling and optimization of activated carbon carbonization process based on support vector machine

80%

Liu G. , Zhang C. , Dou D. , Wei Y.

Physicochemical Problems of Mineral Processing

|

2021

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tom Vol. 57, iss. 2

131--143

EN

Product prediction and process parameter optimization in the production process of activated carbon are very important for production. It can stabilize product quality and improve the economic efficiency of enterprises. In this paper, three process parameters of a carbonization furnace, namely feeding rate, rotation speed, and carbonization temperature, were adopted to build a quality optimization model for carbonized materials. First, an orthogonal test was designed to obtain the preliminary relationship between the process parameters and the quality indicators of a carbonized material and prepare data for modeling. Then, an improved SVR model was developed to establish the relationship between product quality indicators and process parameters. Finally, through the singlefactor experiments and the Monte Carlo method, the process parameters affecting the quality of a carbonized material were determined and optimized. This showed that a high-quality carbonized material could be obtained with a smaller feeding rate, larger rotation speed, and higher carbonization furnace temperature. The quality of activated carbon reached its maximum when the feeding rate was 1.0 t/h, the rotation speed was 90 r/h, and the temperature was 836°C. It can effectively improve the quality of carbonized materials.

9

Semi-active linear vacuum packed particles damper

80%

Zalewski R. , Chodkiewicz P.

Journal of Theoretical and Applied Mechanics

|

2016

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tom Vol. 54 nr 1

311--316

EN

In this paper, the authors focus on the proposition of an innovative semi-active linear damper prototype working on the basis of granular materials. Vacuum Packed Particles (VPP) belong to the class of materials whose mechanical (rheological, dissipative) properties may be quickly changed by applying a partial vacuum inside the system. The concept of an innovative linear damper based on VPP is presented in the paper. Typical experimental results are presented to reveal changeable damping characteristics of the device. Additionally, the mathematical model is proposed to capture extraordinary features of the investigated damper.

10

Visualizing the high-resolution models and microscopic images using web-based systems

80%

Dudek K. J. , Bożek O.

Computer Methods in Materials Science

|

2015

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tom Vol. 15, No.3

427-434

EN

Despite the ongoing automation of image processing and analysis, the need of manual browsing, i. e. visual examination has not diminished. The following article presents a dynamic and highly efficient method of presenting and streaming the large resolution images, using the Linux web-based front-end, built on top of the IIP Image library and tools. This kind of approach solves the problem of local storage and duplication of results, as well as allows a wider group of users to browse and annotate the images. The central image repository, dedicated for managing significant amount of data, has a variety of potential applications, both in research and in teaching. Taking a step sideways, this paper is meant to walk through the initial work and plans related to applying IIP Image in metallurgical imaging, current applications on other fields and suggested teaching scenarios. The system description is followed by a brief performance analysis.

PL

Mimo szybko postępującego rozwoju automatyzacji przetwarzania obrazów, w dalszym ciągu zachodzi potrzeba analizy wizualnej. Praca z obrazami oznacza jednakże przetwarzanie danych o znacznej objętości. Metody generowania, zapisu i przechowywania obrazów są uznawane za detal techniczny, co prowadzi do wykorzystywania nieoptymalnych i nieprzenośnych narzędzi, utrudniających wymianę i prezentowanie informacji w formie obrazów. Poprawa tej sytuacji umożliwiłaby łatwiejszą współpracę (między zespołami i oprogramowaniem), otwierając przy okazji szereg dodatkowych możliwości. Podejmując temat związany' z technicznym zapleczem działalności badawczej, niniejsza praca przedstawia sugerowane rozwiązanie tej zaniedbanej kwestii, oferując system oparty na serwerze obrazów IIP Image, konwerterze VIPS i platformie Apache w środowisku Linux. Opisowi systemu towarzyszy dyskusja nad responsywnością oraz przydatnością w dydaktyce.

11

Ladle nozzle opening and genetic programming

80%

Kovacic M. , Jurjovec B. , Krajnc L.

Computer Methods in Materials Science

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2013

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tom Vol. 13, No. 1

147--152

EN

Štore Steel Ltd. faces a huge problem with ladle nozzle opening during the production of a wide variety of steel grades. After the ladle treatment the steel melt is poured from the ladle through the sliding gate and the nozzle into the tundish on the continuous casting machine. Due to often cloggings the ladle nozzle must be opened with the oxygen which can cause melt pollution. The purpose of this paper is to present the attempt for reducing ladle nozzle openings. In this attempt genetic programming method was used. The experimental data on 115 consequently cast heats was used. The steelmaking technology number, batch sequence number, time spent for secondary metallurgy, sustainability of upper nozzle brick, sustainability of nozzle seating block, sustainability of lower nozzle brick, ladle number, sustainability of the ladle, foreman of the secondary metallurgy and melt chemical composition (Al, C, Mn and Si) were taken into account for the prediction of ladle nozzle opening. The best genetically developed model for ladle nozzle opening prediction correctly predicts 107 out of 115 situations of opening the ladle. The results of the genetic programming based modeling have been used in practice for the changing of several steelmaking technologies.

PL

Firma Štore Steel Ltd. napotkała na poważne problemy związane z otwieraniem wylotu kadzi podczas produkcji szerokiej gamy gatunków stali. W procesie ciągłego odlewania, po stopieniu stali w kadzi otwierana jest przesuwna zasuwa i stal przepływa przez dyszę do kadzi pośredniej. Z powodu częstego zatykania się dyszy kadzi jest ona otwierana przy pomocy tlenu, co powoduje zanieczyszczenie wytopu. Celem niniejszej pracy jest opracowanie technologii eliminującej problem z otwieraniem dyszy kadzi. Do jego realizacji wykorzystano metodę programowania genetycznego. Model oparto na zbiorze danych z różnych wytopów liczącym 115 przypadków. Pojedynczy przypadek zawierał informacje o numerze technologii produkcji stali, numerze partii wytopu, czasie rafinacji pozapiecowej, trwałości górnych cegieł wylotu, trwałości bloków osadzania wylotu, trwałości dolnych cegieł wylotu, numerze kadzi, trwałości kadzi, technologu nadzorującym rafinację pozapiecową oraz składzie chemicznym stopu (Al, C, Mn and Si). Najlepiej dopasowany w oparciu o programowanie genetyczne model otwierania dyszy kadzi przewidywał prawidłowo 107 na 115 przypadków. Wyniki modelowania zastosowano w praktyce usprawniając kilka technologii produkcji stali.

12

Influence of oxygen concentration on combustion characteristics of hydrocarbon-air mixtures under high temperature and pressure

80%

Kanno A. , Kawakami T. , Sutkowski M. , Teodorczyk A.

Journal of KONES

|

2006

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tom Vol. 13, No. 2

197-203

EN

The emission of NOx, SOx, HC and CO2 from internal combustion engines is still a major issue in the development of modern engines. Especially for new concepts, like EGR (Exhaust gas recirculation), developed, detailed information about the pollutant formation is required. However, the experiments of actual standard engines are generally very complicated processes including the residual gas from the last cycle and the flow in an engine cylinder. Thus, experimental data measured using actual engines become unreliable. To obtain the essential data on combustion of hydrocarbon-CO2-N2-O2 mixtures, the experiments have been performed under conditions of high temperature and pressure, which are achieved by a spark ignited opposed rapid compression machine. The main conclusions are as follows: (1) The maximum burning pressure decreases with decreasing oxygen concentration at same EGR ratio. (2) The total burning time decreases with decreasing the concentration of O2 in methane-COx-N2-O2 and propane-CO2-N2-O2 mixtures. (3) The reduction ratio of flame speed is relatively larger on the fuel rich side than that on the lean side. Numerical modeling was focused on the influence of EGR ratio on exhaust emission. Methane fuel was used in the modeling

13

Nagrzewanie indukcyjne w procesie depolimeryzacji

80%

Wesołowski M. , Niedbała R. , Kucharski D.

Zeszyty Naukowe. Elektryka / Politechnika Łódzka

|

2012

|

tom z. 124

241-249

PL

Liczba zastosowań nagrzewania indukcyjnego znacznie wzrosła w stosunku do stanu sprzed kilku lat. Oprócz zwiększenia zakresu typowych zastosowań oraz upowszechnienia grzejnictwa w aplikacjach bytowych, istnieje szereg zastosowań nowych, w których dotychczas wykorzystywano inne metody elektrotermiczne. W niniejszej pracy przedstawiono zastosowanie nagrzewnicy indukcyjnej w procesie termicznej depolimeryzacji plastików. Z punktu widzenia obiektu elektrotermicznego, prezentowany układ stanowi nagrzewnica do objętościowego grzania wsadów w postaci kawałkowej. Zaprezentowano uogólnioną koncepcję układu grzejnego oraz wyniki badań świadczących o pozytywnych cechach tego rodzaju nagrzewania w stosunku do klasycznych rozwiązań opartych o pośrednie nagrzewanie rezystancyjne. Omówiono również problematykę modelowania i projektowania tego typu nietypowych przetworników energii.

EN

The utility and the number of applications of induction heating systems increases in last time. In the article, new induction furnace for thermal depoly-merization was described. The general concept of heating system and the measurement results of physical model of device were discussed. Some aspects of numerical modeling of such unusual electrothermal devices were additionally given.

14

Analytical Method of a Calculation of a Torque Ripple of a Two-Phase Asynchronous Motor Supplied by a PWM Controlled Inverter

80%

Záskalický P.

Maszyny Elektryczne : zeszyty problemowe

|

2013

|

tom Nr 4(100), cz. 2

131--135

EN

The paper deals with steady state calculation of torque and currents ripples of a two-phase asynchronous machine, which is supplied by an IGBT transistors half-bridge connected inverter. The inwerter output voltage is controlled by a PWM of the input DC voltage. The complex Fourier series analysis of the inverter output voltage was made, to obtain a spectrum of the harmonic supply voltages. The different voltage harmonic was applied to the two-phase induction machine model to obtain the electromagnetic torque and currents waveforms for various operation conditions.

15

Evaluation of the impact of changes in the city road system on traffic flows

80%

Pasini L.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

|

2018

|

tom Vol. 22. No 2

135--171

EN

This paper outlines a study carried out to answer the questions asked by an architect of the Siena Municipality Office during a conference at our Department on the managementof traffic flows through the Siena North city road system. The purpose of the study was to ascertain if changes in the road system introduced and included in the new City Developmen tPlan would resolve the current traffic congestion issues. In order to answer this question, we used the technology for the development of vehicle traffic system simulators which was introduced during our previous projects (TASKQuart.14(4) 405,17(3) 155,20(1) 9,20(3) 273).

16

Reliability and maintainability and REMM model

80%

Lewitowicz J.

Journal of KONBiN

|

2006

|

tom No. 2

141--144

EN

The Reliability Enhancement Methodology and Modeling (REMM) can provide alternative metrics from those traditionally used in the engineering community. This problem have outline the metrics available from such techniques and compares them with the more commonly used engineering metrics such as removal rate: MTTF, MTBF, MMFH, MTTR, MTBT, MTBCD.

17

Reliability modelling of water distribution system (WDS) for operation and maintenance needs

80%

Kwietniewski M.

Archives of Hydro-Engineering and Environmental Mechanics

|

2004

|

tom Vol. 51, nr 1

85-92

EN

From the point of view of enterprises dealing with WDS operation and maintenance, parameter assessment of reliability of WDS functioning is one of the basics for the assessment of the quality of water-supply services afforded by enterprises. To make reliability assessment possible, a two-state model of WDS reliability has been proposed. The basic parameter of this model is the probability of satisfactory performance of the system as a function of its reliability. Other, no less important parameters characterizing the model are probability of part fault state, intensity of occurrence of part fault states, average time of satisfactory performance state and average time of part fault state of the system. The model has been used to estimate the function of a definite WDS reliability on the basis of operational research of reliability during 3years of its functioning.

18

Model proposal for total productivity measurement and evaluationin a small and medium manufacturing organisation

80%

Kortisova M. , Gregor M.

Applied Computer Science

|

2006

|

tom Vol. 2, no 2

7---29

19

Dynamic model of nuclear power plant steam turbine

80%

Kulkowski K. , Kobylarz A. , Grochowski M. , Duzinkiewicz K.

Archives of Control Sciences

|

2015

|

tom Vol. 25, no. 1

65--86

EN

The paper presents the dynamic multivariable model of Nuclear Power Plant steam turbine. Nature of the processes occurring in a steam turbine causes a task of modeling it very difficult, especially when this model is intended to be used for on-line optimal process control (model based) over wide range of operating conditions caused by changing power demand. Particular property of developed model is that it enables calculations evaluated directly from the input to the output, including pressure drop at the stages. As the input, model takes opening degree of valve and steam properties: mass flow and pressure. Moreover, it allows access to many internal variables (besides input and output) describing processes within the turbine. The model is compared with the static steam turbine model and then verified by using archive data gained from researches within previous Polish Nuclear Power Programme. Presented case study concerns the WWER-440 steam turbine that was supposed to be used in ˙ Zarnowiec. Simulation carried out shows compliance of the static and dynamic models with the benchmark data, in a steady state conditions. Dynamic model also shows good behavior over the transient conditions.

20

Urban flows simulator based on complex system of queues: procedures for simulator generation

80%

Pasini L. , Sabbatini S.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

|

2016

|

tom Vol. 20, No 1

9--31

EN

In a previous work [1], we have defined an object library that allows the building of architectural models of urban traffic systems. In this work we illustrate the procedures that enable us to produce a system simulator starting from the architectural model of an urban vehicular traffic system.