Wyniki wyszukiwania - BazTech

1

Role of Sand Grains in Sorption Processes by Surface Layers of Components of Sand Moulds

Kaźnica N.

Archives of Foundry Engineering

|

2017

|

Vol. 17, iss. 1

87--92

EN

The results of researches of sorption processes of surface layers of components of sand moulds covered by protective coatings are presented in the hereby paper. Investigations comprised various types of sand grains of moulding sands with furan resin: silica sand, reclaimed sand and calcined in temperature of 700 oC silica sand. Two kinds of alcoholic protective coatings were used – zirconium and zirconium – graphite. Tests were performed under condition of a constant temperature within the range 30 – 35oC and high relative air humidity 75 - 80%. To analyze the role of sand grains in sorption processes quantitavie moisture sorption with use of gravimetric method and ultrasonic method were used in measurements. The tendency to moisture sorption of surface layers of sand moulds according to the different kinds of sand grains was specified. The effectiveness of protective action of coatings from moisture sorption was analyzed as well. Knowledge of the role of sand grains from the viewpoint of capacity for moisture sorption is important due to the surface casting defects occurrence. In particular that are defects of a gaseous origin caused by too high moisture content of moulds, especially in surface layers.

2

Psammon algae: composition and spatial distribution in hygroarenal of eutrophic lake

Kalinowska K., Gorelysheva Z., Ejsmont-Karabin J.

Polish Journal of Ecology

|

2011

|

Vol. 59, nr 1

193-200

EN

Psammon habitats like freshwater sandy shores are the peculiar sites due to high fluctuation of physico-chemical conditions and due to the specific composition of the organisms communities distributed along the horizontal pattern related to the wave action. Taxonomic composition, numbers and biomass of phytopsammon were studied in hygroarenal (shore sand beach wetted by lake waves) of the small beach of the eutrophic Lake Mikołajskie (area 498 ha, max. depth 26 m) (Masurian Lake District, Poland). Samples were collected on one occasion (26 June 2003) from 30 sampling stations distributed parallel to lake shore along 10 m line at three different distances (sampling points A, B, C) from 0 to 60 cm from water line. The studies showed distinct horizontal distribution of psammon algae. Their numbers and biomass varied from 2.22 to 31.85 x 10[^3] cm[^-3] of sand and from 0.49 to 4.69 [my]g cm[^-3] of sand, respectively. Mean numbers in all sampling distances were very similar, while the biomass increased with increasing distance from water line. Cyanoprokaryota, among which Oscillatoria spp. were most numerous species, dominated in the numbers, whereas Bacillariophycea (mainly Stephanodiscus hantzschii Grun. and Fragillaria spp.) constituted significant proportion of the total algae biomass. There were no significant correlations between abundance of algae and size fractions of sand. Among taxonomic groups, only the biomass of Cyanoprokaryota showed positive correlations with trophic parameters (TP, TN). The studies did not show any correlations between phytopsammon and the abundances of ciliates and rotifers, suggesting that different environmental factors as well as organisms of the higher trophic levels may play a decisive role in the development and horizontal distribution of algae in hygroarenal of the beach of the eutrophic lake.

3

ANN modelling for the determination of moulding sand matrix grain size

Jakubski J., Dobosz S. M., Major-Gabryś K.

Archives of Foundry Engineering

|

2011

|

Vol. 11, iss. 4

61-64

EN

One of the modern methods of the production optimisation are artificial neural networks. Neural networks are gaining broader and broader application in the foundry industry, among others for controlling melting processes in cupolas and in arc furnaces, for designing castings and supply systems, for controlling moulding sand processing, for predicting properties of cast alloys or selecting parameters of pressure castings. An attempt to apply neural networks for controlling the quality of bentonite moulding sands is presented in this paper. This is the assessment method of sands suitability by means of detecting correlations between their individual parameters. The presented investigations were obtained by using the Statistica 9.0 program. The aim of the investigations was to select the neural network suitable for prediction the moulding sand matrix grain size on the basis of the determined sand properties such as: permeability, compactibility, and compressive strength.

4

Are community composition and abundance of psammon Rotifera related to grain-size structure of beach sand in lakes?

Ejsmont-Karabin J.

Polish Journal of Ecology

|

2004

|

Vol. 52, nr 3

363-368

EN

The aim of the study was top test the hypothesis that the size distribution of sand grains in lake beach should affect the species composition, densities and body-size structure of psammon communities of Rotifera. Studies were carried out in hydro-, hydro- and euarenal zones of 38 beaches (5 to 50 m long and 1 to 10 m wide) in 16 lakes of different trophic status and morphometry (Masurian Lakeland, Poland). Porosity has no impact on psammon rotifer numbers as well as body-size of animals does not seem to play a significant role in species preference to different size classes of sand grains. However, the significant correlations were found between the rotifer numbers and the share of grain size fraction 0.25 - 1.00 mm (positive) and the share of the largest (i.e. > 1 mm) fraction (negative). The psammobionts generally are more related to the grain size ffraction 0.5-1.0 mm than the psammoxenes and psammophiles. Although particular rotifer species prefer different grain size fractions, bdelloids arre the only grroup of Rotifera preferring the smallest (<0.125 mm) grain fraction.

5

Исследование возможности увеличения прочности формовочной смеси

Gruzman V. M., Burdakov K. A.

Archiwum Odlewnictwa

|

2004

|

R. 4, nr 13

81--83

RU

В статье рассматривается метод альтернативного нанесения связующего на зерна песка. Показана возможность получения формовочной смеси с большей удельной прочностью.

EN

The paper considers questions of alternate drawing binder on grains of sand. Displays an opportunity of a sand mix reception with the greater unit strength.

PL

W artykule przedstawiono dwa sposoby nanoszenia materiału wiążącego na powierzchnię ziarn osnowy piaskowej i wpływ tych sposobów na uzyskiwaną wytrzymałość masy. Celem tych badań było wyeksponowanie takich sposobów nanoszenia materiału wiążącego na powierzchnię ziarn osnowy, które umożliwiają uzyskanie wymaganej wytrzymałości masy przy zmniejszonym dodatku materiału wiążącego. Pierwszy sposób dotyczył mas zamrożonych. Wodę, stanowiącą materiał wiążący, nanoszono na powierzchnię ziarn osnowy metodą desublimacji w warstwie fluidyzacyjnej. Pozwoliło to na naniesienie wody tylko na występy chropowatej powierzchni ziarn (bez wnikania wody w zagłębienia tej powierzchni). Przeprowadzone badania masy zawierającej dodatek 1% wody, sporządzonej metodą standardową (w mieszarce laboratoryjnej) i metodą desublimacji wykazały, że masa sporządzona metodą desublimacji miała wytrzymałość na ściskanie około dwukrotnie większą (0,24-0,26 MPa) od masy sporządzonej w mieszarce laboratoryjnej (0,10-0,12 MPa). Druga metoda polepszenia wytrzymałości miała na celu wykazanie, że stworzenie warunków do adhezyjnego niszczenia wiązań między ziarnami masy może dać lepsze wyniki pod względem wytrzymałości masy. Przeprowadzone badania wykazały, że przy tej samej grubości warstewki organicznego materiału wiążącego stworzenie warunków do adhezyjnego niszczenia wiązania znacznie zwiększa wytrzymałość masy.