Wyniki wyszukiwania - BazTech

1

The effect of long term service at elevated temperatures on microstructure degradation of austenitic reformer tubes

Łabanowski J., Jurkowski M., Landowski M.

Advances in Materials Science

|

2018

|

Vol. 18, nr 2(56)

27--36

EN

The paper analyses the relationship between an increase of the inner diameter of tubes made of Manaurite XM cast steel and transformations occurring in their microstructure due to long-lasting operation in methane reformer. Examinations included metallographic analysis with light microscope (LM), scanning electron microscope (SEM) and microanalysis of the chemical composition of precipitates (EDX). It was indicated that there is a relationship between the microstructure degradation ratio, morphology of the precipitates and an increase of the inner diameter of the tubes.

2

RDM interval method for solving quadratic interval equation

Landowski M.

Przegląd Elektrotechniczny

|

2017

|

R. 93, nr 1

65--68

EN

The main task of uncertainty theory is to find the solution with uncertain variable. The ways of uncertainty description are probability density distribution, possibility distribution or interval. To solve the problem with uncertainty variable the calculation on interval is needed. The article presents the usage of RDM interval arithmetic for solving quadratic interval equation. The results obtained from examples are compared with Moore’s standard interval arithmetic solutions.

PL

Głównym zadaniem teorii niepewnos´ci jest znalezienie rozwiazania ze zmienna˛ niepewna˛. Niepewnos´c´ moz˙na zapisac´ w postaci rozkładu ge˛stos´ci prawdopodobien´stwa, rozkładu moz˙liwos´ci lub przedziału. Do rozwia˛zania zadania ze zmienna˛ niepewna˛ potrzebne sa˛ obliczenia na przedziałach. Artykuł przedstawia wykorzystanie arytmetyki interwałowej RDM do rozwia˛zania interwałowych równan´ kwadratowych. Wyniki otrzymane z przykładów porównano z rozwia˛zaniami standardowej arytmetyki interwałowej Moore’a.

3

Is an interval the right result of arithmetic operations on intervals?

Piegat A., Landowski M.

International Journal of Applied Mathematics and Computer Science

|

2017

|

Vol. 27, no. 3

575--590

EN

For many scientists interval arithmetic (IA, I arithmetic) seems to be easy and simple. However, this is not true. Interval arithmetic is complicated. This is confirmed by the fact that, for years, new, alternative versions of this arithmetic have been created and published. These new versions tried to remove shortcomings and weaknesses of previously proposed options of the arithmetic, which decreased the prestige not only of interval arithmetic itself, but also of fuzzy arithmetic, which, to a great extent, is based on it. In our opinion, the main reason for the observed shortcomings of the present IA is the assumption that the direct result of arithmetic operations on intervals is also an interval. However, the interval is not a direct result but only a simplified representative (indicator) of the result. This hypothesis seems surprising, but investigations prove that it is true. The paper shows what conditions should be satisfied by the result of interval arithmetic operations to call it a “result”, how great its dimensionality is, how to perform arithmetic operations and solve equations. Examples illustrate the proposed method of interval computations.

4

Ocena stanu degradacji rur katalitycznych ze staliwa Manaurite XM po długotrwałej eksploatacji w podwyższonej temperaturze

Łabanowski J., Jurkowski M., Landowski M.

Instal

|

2017

|

nr 10

9-13

PL

W artykule poruszono temat dotyczący oceny stanu degradacji rur katalitycznych ze staliwa Manaurite XM po długotrwałej eksploatacji w podwyższonej temperaturze. Spośród wielu mierników stanu degradacji materiału rur analizowano przyrost średnicy wewnętrznej rury, obraz mikrostruktury oraz właściwości mechaniczne w temperaturze pokojowej. Przeprowadzono statyczne próby rozciągania materiału rur, badania metalograficzne mikroskopowe z wykorzystaniem mikroskopu świetlnego (LM) i skaningowego mikroskopu elektronowego (SEM). Z przeprowadzonych badań wynika, że przyrost średnicy wewnętrznej rury o około 3,0% wiąże się z istotnym postępem degradacji mikrostruktury, jednak jeszcze bez oznak tworzenia się porów pełzaniowych. Wykazano, że do statycznej próby rozciągania należy używać próbek zawierających tylko materiał ze środkowej części grubości ściany rury, bez surowych powierzchni, ponieważ pozwalają w sposób wiarygodny określić właściwości mechaniczne zdegradowanego materiału rury w temperaturze otoczenia.

EN

This paper discusses the assessment of the degradation of Manaurite XM catalytic tubes after long term service at elevated temperatures. Out of numerous measures of the degradation state of the catalytic tube material, the increase of the inner diameter of the tube, the microstructure image and the mechanical properties at room temperature were analysed. Static tensile tests, metallographic examinations with Light Microscope (LM) and Scanning Electron Microscope (SEM) were performed. The research shows that increasing the inner diameter of the tube by about 3.0% is associated with significant progression of the microstructure degradation, but without the signs of voids forming. It has been shown that specimens containing only the central portion of the wall thickness of the tube, without raw surfaces should be used for static tensile testing, as they reliably determine the mechanical properties of the degraded catalytic tube material at room temperature.

5

Effect of Long Term Service at Elevated Temperatures on Mechanical Properties of Manaurite XM Reformer Tubes

Łabanowski J., Jurkowski M., Landowski M.

Advances in Materials Science

|

2016

|

Vol. 16, nr 4(50)

38--44

EN

Microstructure transformations occur in the Manaurite XM cast steel tubes during long-term operation in the reformer furnace were revealed and described. The relationship between mechanical properties, an increase of internal diameter of the tube and microstructure degradation is discussed. Static tensile test was performed on two types of samples with different shapes. It has been shown differences in the results of tests and an explanation of this phenomenon.

6

Spawalność tytanu Grade 2 na przykładzie płaszczowo-rurowego wymiennika ciepła

Rogalski G., Fydrych D., Landowski M., Łabanowski J.

Przegląd Spawalnictwa

|

2015

|

R. 87, nr 10

17--22

PL

W artykule scharakteryzowano właściwości, obszary zastosowania i problemy związane ze spawalnością tytanu i jego stopów. Opracowano technologię spawania metodą TIG płaszczowo-rurowego wymiennika ciepła typu JAD B z tytanu Grade 2, zaprezentowano wyniki badań nieniszczących i niszczących złączy spawanych. Szczególną uwagę zwrócono na trudności związane z przygotowaniem krawędzi elementów do spawania i wynikające z nich niezgodności spawalnicze.

EN

The article describes the properties, application areas and problems with the weldability of titanium and its alloys. Procedure of TIG welding of shell and tube heat exchanger JAD B made of Grade 2 titanium was qualified and the results of non-destructive and destructive testing of welds were presented. Particular attention was paid to the difficulties associated with the preparation of edges before welding and as a result to the welding imperfections.

7

Impact behaviour of glass fribre /epoxy composites with nano-enhanced resin after water exposure

Landowski M., Imielińska K.

Advances in Materials Science

|

2015

|

Vol. 15, nr 2(44)

30--35

EN

Impact behaviour of glass fibre /epoxy composites with nano- SiO2 modified resin was studied in terms of low velocity impact after water exposure. Nanocomposites with 1%, 2%, 3% 5% 7% nano-SiO2 (Nanopox- Evonic) were investigated. Peak impact load and impact damage area as a function of nanoparticle contents were compared for dry specimens and for samples exposed to water (0.7 %wt. 1.7% water absorbed) at 1J, 2J 3J impact energies. For unmodified composite peak force was higher than for 3% modified specimens and higher for dry specimens than those exposed to water. Impact damage areas were plotted as a function of water contents for modified and unmodified samples. Failure modes were illustrated using SEM micrographs. Numeropus matrix cracks were the dominating failure mode in dry speciemens both unmodified and the modified. Fibre fracture was observed at 3J impact energy in all dry unmodified samples, however water exposure prevented early fibre fracture in nanocomposites. The proposed energy absorption mechanism is nanoparticles debonding.

8

Preliminary studies of seamless flux-cored wires stored in extreme conditions

Fydrych D., Świerczyńska A., Landowski M.

Metallurgy and Foundry Engineering

|

2014

|

Vol. 40, no. 4

211--220

EN

In this paper, we describe the preliminary experimental studies of flux-cored wires moisturized under controlled conditions. Three seamless wires of different grades have been placed in an environmental chamber and moisturized in extremely adverse conditions (temperature T = 60°C, relative humidity H = 90%) for 240 hours. During this time, measurements of weight gain as well as surface observations of the wires have been carried out. Also, the amount of diffusible hydrogen in deposited metal was determined by the mercury method for one of the moisturized wires. A significant increase in the level of hydrogen was observed (from H5 to H10). Further research will aim to determine the effect of storage conditions on the hydrogenation of deposited metal and quality of flux-cored wires.

PL

Praca dotyczy badań drutów proszkowych nawilżanych w kontrolowanych warunkach. Trzy gatunki drutów bezszwowych umieszczono w komorze klimatycznej i nawilżano w niekorzystnych warunkach (temperatura T = 60°C, wilgotność względna H = 90%) przez 240 h. Badania polegały na pomiarze nasiąkliwości i ocenie stanu powierzchni badanych drutów. Ponadto dla jednego z nawilżanych drutów oznaczono metodą rtęciową zawartość wodoru dyfundującego w stopiwie. Stwierdzono znaczny wzrost poziomu wodoru (z H5 do H10). Dalsze badania powinny zmierzać do ilościowego ustalenia wpływu warunków przechowywania na nawodorowanie stopiwa i jakość badanych drutów.

9

RDM interval arithmetic for solving economic problem with uncertain variables

Landowski M.

Logistyka

|

2014

|

nr 6

EN

Uncertain variables are often used for solving realistic problems. To find the solution of a realistic problem the model with uncertain variable has to be built. Based on the model with uncertain variables operations on intervals are necessary. The article presents the multidimensional RDM interval arithmetic and its application to solving an economic problem. Obtained solutions are compared with results from the one dimensional Moore interval arithmetic and global optimization.

10

Specialized, MSE-optimal m-estimators of the rule probability especially suitable for machine learning

Piegat A., Landowski M.

Control and Cybernetics

|

2014

|

Vol. 43, no. 1

133--160

EN

The paper presents an improved sample based rule- probability estimation that is an important indicator of the rule quality and credibility in systems of machine learning. It concerns rules obtained, e.g., with the use of decision trees and rough set theory. Particular rules are frequently supported only by a small or very small number of data pieces. The rule probability is mostly investigated with the use of global estimators such as the frequency-, the Laplace-, or the m-estimator constructed for the full probability interval [0,1]. The paper shows that precision of the rule probability estimation can be considerably increased by the use of m-estimators which are specialized for the interval [phmin, phmax] given by the problem expert. The paper also presents a new interpretation of the m-estimator parameters that can be optimized in the estimators.

11

Mean square error optimal completeness estimator Eph2 of probability

Piegat A., Landowski M.

Journal of Theoretical and Applied Computer Science

|

2013

|

Vol. 7, nr 3

3--20

EN

The paper presents the optimal estimator of probability for the binomial and multinomial case that was called ”completeness estimator Eph2” and theoretical proof of its optimality. The estimator accuracy was compared with accuracy of the universally used frequency estimator. The comparison was realized both theoretically and experimentally. Both comparison ways show superiority of the completeness estimator Eph2 over the frequency estimator frh = nh=n. A prooved solution of the single case problem is given.

12

Analiza obciążeń działających na dzieci w fotelikach zamocowanych przodem i tyłem do kierunku jazdy w czasie zderzenia czołowego

Zdunek B., Landowski M., Taryma S., Woźniak R., Imielińska K., Muszyński A.

Autobusy : technika, eksploatacja, systemy transportowe

|

2013

|

R. 14, nr 10

311-314

PL

W artykule omówione zostały podstawowe problemy ochrony dzieci w czasie kolizji drogowych. Przedstawione zostały dwa sposoby mocowania fotelików: przodem i tyłem do kierunku jazdy. Opisane i porównane zostały przebiegi obciążeń głowy w czasie uderzenia pojazdu w sztywną ścianę betonową.

EN

Paper describes the basic problems of children protection during collisions. Presented and compared were head deceleration during vehicle impact with a rigid concrete wall for two ways of fixing child seats: front and rear-facing.

13

Dynamic mechanical behaviour of gfrp composites with SiO2 nano particles reinforced epoxy matrix

Landowski M., Budzik M., Imielińska K.

Advances in Materials Science

|

2013

|

Vol. 13, nr 4(38)

5--8

EN

Dynamic mechanic (DMA) tests were performed to compare the mechanical behaviour of glass fibre reinforced epoxy laminate composites with SiO2 nanoparticle reinforced matrix. The selection of the most promising nanoparticle concentrations was considered in terms of elastic modulus and glass transition temperature. The reference specimens (0% nanoparticles) did not contain diluent accordingly the results do not allow the exact comparison with unreinforced composite, nevertheless the ranking of the nanocomposites was made. In terms of stiffness requirements 20% nanoparticles composites offer the best behaviour, 25% higher elastic modulus than 5% nanoparticles. For nano composites the glass transition temperature TG is the highest: 80°C, 77°C for 3%, 5% nanoparticles respectively and the lowest 75°C, 72°C , 71°C for 15%, 10% and 20% nanoparticles is respectively .

14

Degradation of GFRP Marine Laminates with Nano Particle Modified Coatings

Landowski M., Imielińska K.

Advances in Materials Science

|

2013

|

Vol. 13, nr 2(36)

19--22

EN

Water absorption and surface blistering behaviour was studied for polyester-matrix laminates with SiO2 nanoparticle reinforced gel coats. Accelerated water immersion tests at 37°C showed that addition of 10% nanoparticles increases blisters incubation time by ca. 50% compared to 5% and 0% nanoparticles composites.

15

Is the conventional interval arithmetic correct?

Piegat A., Landowski M.

Journal of Theoretical and Applied Computer Science

|

2012

|

Vol. 6, nr 2

27-44

EN

Interval arithmetic as part of interval mathematics and Granular Computing is unusually important for development of science and engineering in connection with necessity of taking into account uncertainty and approximativeness of data occurring in almost all calculations. Interval arithmetic also conditions development of Artificial Intelligence and especially of automatic thinking, Computing with Words, grey systems, fuzzy arithmetic and probabilistic arithmetic. However, the mostly used conventional Moore-arithmetic has evident weak-points. These weak-points are well known, but nonetheless it is further on frequently used. The paper presents basic operations of RDM-arithmetic that does not possess faults of Moore-arithmetic. The RDM-arithmetic is based on multi-dimensional approach, the Moore-arithmetic on one-dimensional approach to interval calculations. The paper also presents a testing method, which allows for clear checking whether results of any interval arithmetic are correct or not. The paper contains many examples and illustrations for better understanding of the RDM-arithmetic. In the paper, because of volume limitations only operations of addition and subtraction are discussed. Operations of multiplication and division of intervals will be presented in next publication. Author of the RDM-arithmetic concept is Andrzej Piegat.

16

Optimal estimator of hypothesis probability for data mining problems with small samples

Piegat A, Landowski M.

International Journal of Applied Mathematics and Computer Science

|

2012

|

Vol. 22, no. 3

629-645

EN

The paper presents a new (to the best of the authors' knowledge) estimator of probability called the "[...] completeness estimator" along with a theoretical derivation of its optimality. The estimator is especially suitable for a small number of sample items, which is the feature of many real problems characterized by data insufficiency. The control parameter of the estimator is not assumed in an a priori, subjective way, but was determined on the basis of an optimization criterion (the least absolute errors).The estimator was compared with the universally used frequency estimator of probability and with Cestnik's m-estimator with respect to accuracy. The comparison was realized both theoretically and experimentally. The results show the superiority of the [...] completeness estimator over the frequency estimator for the probability interval ph (0.1, 0.9). The frequency estimator is better for ph [0, 0.1] and ph [0.9, 1].

17

Water sorption and blistering of GFRP laminates with varying structures

Landowski M., Budzik M., Imielińska K.

Advances in Materials Science

|

2012

|

Vol. 12, nr 4(34)

23-29

EN

The microstructures, water absorption as well as blistering was studied for bi- and tri- axial glass fibre vinyl ester and polyester -matrix laminates coated with gel coat layer and uncoated. The effect of manufacturing technique on water sorption characteristics was considered. It was found that water sorption characteristics of GFRP depend on manufacturing methods. The least water intake was found for specimens having perfect microstructure due to manufacturing by infusion process. Water sorption saturation value was reached after ca. 50 days of accelerated test at 70°C and was found to correspond to 250 days conditioning at 20°C. Blistering evolution was illustrated and SEM images shown corresponding to degradation of the gel coat layer and the laminate during the exposure in water.

18

Nowy estymator prawdopodobieństwa hipotez Eph1 i wyniki badań jego dokładności

Piegat A., Landowski M.

Metody Informatyki Stosowanej

|

2011

|

nr 1

93-106

PL

W artykule przedstawiono nowy, kompletnościowy estymator prawdopodobieństwa Eph1 oraz wyniki badań porównujących dokładność tego estymatora jak również powszechnie stosowanego obecnie estymatora częstościowego frh = nt/n. Wyniki badań obejmujące łącznie 11000 eksperymentów, z których każdy zawierał 10000 liczb (0 lub 1) generowanych z zadanym prawdopodobieństwem ph, (0.01, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.99) wykazały dużą przewagę, pod względem dokładności, kompletnościowego estymatora Eph1 nad estymatorem częstościowym frh dla małej liczby próbek n < 25 oraz bardzo zbliżoną dokładność obydwu estymatorów dla większej liczby próbek n > 25 . W szczególno-ści, estymator Ephi ze wzrostem liczby próbek n jest zbieżny do estymatora frh i do prawdopodobieństwa ph, gdy n -∝, tak samo jak estymator częstościowy. W artykule podano także przybliżone, średnie liczby próbek n0,05 i n0,01 konieczne do estymacji prawdopodobieństwa ph, z błędem poniżej 0.05 oraz 0.01 określone na podstawie eksperymentów. Badania wykazały, że estymator częstościowy frh, umożliwia oszacowanie z wysoką dokładnością jedynie prawdopodobieństw zbliżonych do zera lub jedności. Największy błąd wykazuje w przypadku prawdopodobieństw zbliżonych do 0.5. Natomiast nowy estymator kompletnościowy posiada w przybliżeniu podobną dokładność dla każdej wartości prawdopodobieństwa. W przypadku małej liczby próbek dokładność ta jest znacznie wyższa niż dokładność estymatora częstościowego frh = nh/n. W niniejszym artykule autorem estymatora kompletnościowego Eph1 jest A. Piegat, natomiast oprogramowanie do eksperymentów oraz same eksperymenty przeprowadził M. Landowski.

EN

The frequency estimator of probability frh=nh/n is widely used in science. However, scientists discovered many weakpoints of this estimator and therefore proposed afew other interpretations of probability that differ form the frequency interpretation. In this paper a new (according to authors' knowledge) completeness estimator of probability, denoted as Eph1, is proposed. Computer experiments realized by authors for comparative aims shown identical accuracy of he new estimator Eph1 and frequency estimator frh for large numbers of samples and a considerably higher accuracy of EpM estimator for small numbers of samples n<25. Because with insufftcient small number of samples we often have to do in practical problems therefore application of the new estimator seems very useful and recommendable.

19

Wpływ metody wytwarzania na właściwości laminatów poliestrowo/ szklanych do budowy małych jednostek pływających

Landowski M., Budzik M. K., Imielińska K.

Inżynieria Materiałowa

|

2011

|

Vol. 32, nr 5

868-872

PL

W pracy porównano jakość laminatów poliestrowo/szklanych (pod względem mikrostrukturalnym i wybranych wskaźników wytrzymałościowych) wytworzonych w zakładzie budowy dużych łodzi motorowych za pomocą metod: ręcznej, worka próżniowego i infuzji. Badano jakość struktury pod kątem udziału osnowy żywicznej i liczby pęcherzy za pomocą SEM (rys. 3) i analizy ilościowej obrazu. Próbki wykonane metodą ręczną, worka próżniowego i infuzji wykazały udział objętościowy osnowy odpowiednio: Vm = 51%, 23%, 35%. Zróżnicowany udział żywicy w kompozycie wpłynął na jego grubość: 3,8 mm - metoda ręczna, 2,6 mm - metoda worka próżniowego i 2,7 mm - metoda infuzji. Porównano własności mechanicznena podstawie wyników prób: trzypunktowego zginania (rys. 4), ścinania międzywarstwowego (rys. 5), udarności wyznaczonej metodą Charpy'ego i spadającej masy (rys. 6). Wyniki badań wytrzymałości na zginanie nie ujawniły znaczących różnic w wytrzymałości na zginanie i modułu Younga próbek wykonanych różnymi metodami. Różnica rzędu 10% na niekorzyść metody ręcznej wynika z większego udziału słabej osnowy żywicznej i nieco większej liczby pęcherzy. Zaobserwowano natomiast 20% mniejsze odkształcenie przy pękaniu (rys. 4) i 25% mniejszą udarność (rys. 6) w przypadku metody worka próżniowego w porównaniu z metodą infuzji. Było to spowodowane licznymi mikropęknięciami pomiędzy włóknami (rys. 3d, e.), które pojawiły się w miejscach "suchego" styku włókien w laminacie na skutek lokalnie nadmiernego odessania żywicy. Ogólnie stwierdzono, że biorąc pod uwagę uzyskane wyniki, lepszą wydajność oraz mniejszą szkodliwość dla zdrowia pracowników jest uzasadnione propagowanie metody infuzji w polskim przemyśle okrętowym.

EN

Microstructural SEM characteristics (Fig. 3) and mechanical behaviour were compared for glass/polyester laminates manufactured in the boatbuilding plant using three methods: hand lay-up, vaccum bagging, infusion. Microstructure was assessed in terms of matrix Vm and void volume fraction using quantitative image analysis. Vm was found 51%, 23%, 35%, respectively. Differences in Vm affected laminate thickness which was fund 3.8 mm for hand lay-up method, 2.6 mm for vacuum bagging and 2.7 mm for infusion. Mechanical behaviour was characterized using three point bending test (Fig. 4), interlaminar shear strength (Fig. 5), Charpy impact and drop weight tests (Fig. 6). Bending test results did not vary much between the methods. Maximum difference of flexural strength and Young's modulus of about 10% in favour of the two vacuum methods (Fig. 4) was due lesser Vm and VV. However, significantly (20%) reduced deformation at fracture and 25% reduced impact strength were observed (Fig. 6) for vacuum bagging method compared to infusion. This was due to numerous debondings and microcracks which formed between the fibres (Fig. 3d, e) in the "dry" spots where fibres were not separated by the resin layer because of locally excessively small matrix content. Based on the results of experiments and knowledge about the impact of polymer laminate manufacturing methods on the environment it has been concluded that infusion method should be recommended to the Polish boat building plants not only due to improved efficiency and harmlessness to the workers' health but also because of improved mechanical behaviour of the materials.

20

On degradation of glass/polyester laminate immersed in water

Landowski M., Budzik M., Imielińska K.

Advances in Materials Science

|

2011

|

Vol. 11, nr 1(27)

35-39

EN

Mechanical behaviour was compared for glass/ polyester laminates manufactured in the boatbuilding plant using three methods: hand lay-up, vacuum bagging, infusion. Specimens were tested in dry condition and following accelerated water immersion test (700C- corresponding to the exposure of 30 years at 190C). In three point bending test 40-50% reduction in laminate strength was observed due to water immersion. The highest degradation was in samples manufactured using hand lay-up method, the differences in strength between both vacuum methods were insignificant. Interlaminar shear strength was reduced by 25% for infusion method which is recommended as the most efficient. Matrix plasticization and debondings as well as surface microcracks were responsible for reduction in strength for water conditioned specimens. However, no microstructural difference in type or intensity of internal damage was observed for the three sample types.