Wyniki wyszukiwania - Biblioteka Nauki

1

Prognozowane wysokości opadów do 2050 roku w świetle obserwowanych zmian klimatu we Wrocławiu

100%

Kaźmierczak B. , Wartalska K. , Nowakowska M. , Kotowski A.

Gaz, Woda i Technika Sanitarna

|

2019

|

tom Nr 8

250--254

PL

W pracy podjęto próbę predykcji przyszłych opadów maksymalnych, miarodajnych do wymiarowania systemów odwodnień terenów zurbanizowanych. Materiałem badawczym były archiwalne zapisy pluwiograficzne ze stacji IMGW-PIB we Wrocławiu z 59. lat obserwacji (1960-2018). Opracowany model maksymalnych wysokości opadów ma zastosowanie dla czasów trwania od 5 do 4320 minut i częstości występowania od 1 do 50 lat dla okresu predykcji opadów na lata 2020-2050. Na podstawie przeprowadzonych badań przewiduje się wzrost wysokości opadów krótkotrwałych i spadek wysokości opadów długotrwałych w perspektywie do 2050 roku.

EN

The paper attempts to predict future maximum rainfall, reliable for dimensioning drainage systems. The research material was archival pluviographic records from the IMGW-PIB station in Wroclaw from 59 years of observations (1960-2018). The developed model of maximum rainfall amounts is applicable for durations from 5 to 4320 minutes and frequency of occurrence from 1 to 50 years for the period of rainfall prediction for 2020-2050. On the basis of the conducted research, an increase in short-term rainfall amounts and a decrease in long-term rainfall amounts are expected.

2

Analiza niestacjonarności czasoprzestrzennej deszczów na przykładzie walidacji modelu hydrodynamicznego SWMM

100%

Nowakowska M. , Kaźmierczak B. , Wartalska K. , Kotowski A.

Inżynieria Morska i Geotechnika

|

2021

|

tom nr 2

47--54

PL

Wybrane problemy związane z prowadzeniem badań symulacyjnych zjawiska opad – odpływ w programie SWMM. Metodyka i wyniki analizy czasoprzestrzennych zmian wysokości opadów deszczowych na obszarze zlewni miejskiej. Badania przeprowadzone na referencyjnej zlewni deszczowej osiedli mieszkaniowych Gaj i Tarnogaj we Wrocławiu, opomiarowanej w lokalnej sieci 6 deszczomierzy. Projekcja zastępczego hietogramu dla środka ciężkości badanej zlewni dokonana dla przykładowego, intensywnego deszczu w programie Surfer®13, z zastosowaniem metody odwrotnych odległości, dla 5-minutowych interwałów czasowych. Niestacjonarność badanego opadu co do czasu trwania i przedziałowej intensywności – już w najbliższym sąsiedztwie deszczomierza i jej wpływ na wyniki walidacji modeli hydrodynamicznych, stosowanych m.in. do ocen niezawodności działania systemów odwodnień terenów zurbanizowanych.

EN

Selected problems related to the simulation of the rainfall-runoff phenomenon in the SWMM program. The methodology and results of the analysis of space-time changes in the amount of rainfall in the urban catchment area. The research carried out on the reference rainwater catchment area of Gaj and Tarnogaj housing estates in Wrocław, measured in the local network of 6 rain gauges. A projection of a substitute hietogram for the center of gravity of the studied catchment made for an exemplary, intense rainfall in the Surfer®13 program, using the inverse distance method, for 5-minute time intervals. The non-stationarity of the rainfall under study in terms of duration and intensity interval – already in the immediate vicinity of the rain gauge and its impact on the results of validation of hydrodynamic models, used e.g. to assess the reliability of operation of drainage systems in urbanized areas.

3

The effect of spray distance on porosity, surface roughness and microhardness of WC-10Co-4Cr coatings deposited by HVOF

100%

Górnik M. , Jonda E. , Nowakowska M. , Łatka L.

Advances in Materials Science

|

2021

|

tom Vol. 21, nr 4(70)

99--111

EN

The paper presents the computational studies on the microstructure of WC-Co-Cr coatings deposited by High Velocity Oxy Fuel spraying (HVOF). The study covers the porosity assessment according to ASTM E2109-01 standard, carried out in ImageJ software, in terms of volume porosity, size and shape of the pores. The evaluation was preceded by scanning electron microscope (SEM) observations at magnifications of 2000x and 5000x. Additionally, topography analysis has been performed by confocal laser scanning microscope (CLSM), and the surface roughness Ra was evaluated by the contact method with use of a stylus profilometer. Finally, the influence of porosity was observed for coatings microhardness HV0.3. According to the results, the total closed porosity was found to be in the range of 5.01 vol.% and 5.38 vol.%. The dominated pores in the coatings were of size 0.1-1.0 μm. Studies showed that HVOF process enabled deposition of dense coatings, characterized by homogenous distribution of pores and low roughness.

4

The influence of injection mode and spray distance on wear resistance of Al2O3+13 wt.% TiO2 coatings

100%

Płatek K. , Łatka L. , Nowakowska M.

Advances in Materials Science

|

2024

|

tom Vol. 24, nr 3(81)

5--17

EN

Atmospheric plasma spraying (APS) allows deposition of ceramic coatings on metallic substrate, significantly increasing the wear resistance of the component. Coating’s microstructure and consequently its properties, depend on heat treatment of the feedstock particles. This property can be controlled by process parameters, especially electric power and spray distance. On the other hand, some plasma torches allow introducing another variable, an injection mode, which could be realized in external or in internal way. In the presented research, wear resistance of Al2O3+13 wt.% TiO2 coatings deposited under various values of spray distance and different injection modes were examined using ASTM G-99 procedure. The impact of spraying parameters on the coating’s microstructure was established and connected to the functional properties of the manufactured deposits. Observed differences indicated influence of injection mode and spray distance value. Coatings deposited with internal feedstock injection exhibit lower porosity and slightly higher hardness than these made with external injection mode. In terms of wear resistance for both spray distance the wear factor was lower for internal injection system. Obtained results confirmed assumed thesis, that internal injection mode improves heat treatment and consequently ameliorate wear performance of plasma sprayed alumina-titania coatings.

5

Współczesne standardy obliczeń hydraulicznych kanałów ściekowych i deszczowych

100%

Kotowski A. , Kaźmierczak B. , Nowakowska M. , Wartalska K.

Technologia Wody

|

2019

|

tom Nr 3 (65)

32--37

PL

W pracy zaprezentowano aktualny stan wiedzy w zakresie bezpiecznego wymiarowania hydraulicznego kanałów, zgodnie z najlepszą dostępną wiedzą techniczną. Omówiono trzy metody obliczeń przepływów cieczy w kanałach: metodę opartą na uniwersalnym wzorze Colebrooka-White’a z zastępczą chropowatością (k) – zalecaną przez normę PN-EN 752; metodę opartą na wzorze Manninga ze współczynnikiem szorstkości (n) – dla przepływów turbulentnych w strefie kwadratowego prawa oporów oraz metodę opartą na zmienionej postaci wzoru Manninga – z zastępczą chropowatością (k), zalecaną przez normę PN-EN 752 dla tej strefy. Sformułowano także zalecenia do doboru parametrów hydraulicznych kanałów ściekowych i deszczowych.

EN

The paper presents the current state of knowledge in the field of safe hydraulic dimensioning of channels, in accordance with the best available technical knowledge. Three methods of calculating liquid flows in channels are discussed: a method based on the universal Colebrook-White formula with substitute roughness (k) – recommended by the PN-EN 752 standard; the method based on the Manning formula with the coefficient of roughness (n) – for turbulent flows in the square zone of the resistance law; and a method based on the changed form of the Manning formula – with substitute roughness (k), recommended by the PN-EN 752 standard for this zone. Recommendations for the selection of hydraulic parameters for sewage and rain channels were also formulated.

6

Al2O3-TiO2 coatings deposition by intermixed and double injection SPS concepts

88%

Nowakowska M. , Sokołowski P. , Tesař T. , Mušálek R. , Kiełczawa T.

Materials Science Poland

|

2021

|

tom Vol. 39, No. 4

599--614

EN

This work focuses on the study on the novel hybrid method of simultaneous spraying from two different materials (Al2O3 and TiO2) by means of suspension plasma spraying (SPS) using submicron powder and water suspension. The goal was to attempt the deposition of intermixed alumina-titania coatings, namely: Al2O3 + 3 wt.% TiO2, Al2O3 + 13 wt.% TiO2, and Al2O3 + 40 wt.% TiO2. Such compositions are already used but in the form of conventionally plasma sprayed coatings, with micrometer-sized powder. Meanwhile, the injection of feedstocks with submicron-sized particles has not been established yet. In particular, this paper uses two routes of feedstock injection, (i) with the use of an intermixed suspension and (ii) a double injection of separate suspensions. The attention was paid to the characterization of the feedstock materials, description of deposition parameters as well as the morphology, microstructure, and phase composition of the obtained coatings. Among all coatings, Al2O3 + 40 wt.% TiO2 sprayed with double injection contained the most homogeneously distributed and melted splats. The results from this work demonstrate the possibility of coating deposition both by intermixed and double injection concepts but also the need for the further application-relevant optimization, related to the presence of intercolumnar gaps in the microstructure of the coatings.

7

Influence of spray distance on mechanical and tribological properties of HVOF sprayed WC-Co-Cr coatings

88%

Górnik M. , Jonda E. , Łatka L. , Nowakowska M. , Godzierz M.

Materials Science Poland

|

2021

|

tom Vol. 39, No. 4

545--554

EN

In this work, the tungsten carbide reinforcement in cobalt matrix (WC-Co-Cr) coatings was studied. The deposition process was carried out by high-velocity oxy-fuel spraying (HVOF). The study aimed to investigate the influence of one of the key process parameters, namely spray distance, on the coatings’ microstructure and phase composition, as well as their mechanical and tribological properties. The manufactured coatings were analysed by scanning electron microscopy, X-ray diffraction (XRD), instrumented indentation test, pull-off adhesion test and ball-on-disc method. The results revealed that selection of proper spray distance caused a high index of carbide retention (ICR) amounting to 0.95, which promoted higher hardness and better wear resistance. Instrumental microhardness was in the range of 14.2–14.8 GPa, whereas the Young modulus exhibited values from 336 GPa up to 342 GPa. The bond strength of deposited coatings was in the range of 55–65 MPa. Wear factor values were in the range of 73–81 × 10−7 mm3/(N · m) and the friction coefficient was about 0.4. The dominant wear mechanism is abrasion and adhesive mode supported by the fatigue-induced material delamination.