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Planctonic Rotifera in the Collapse Pond on the Łąkawka River (Bojszowy - Jedlina)

Irena Bielańska-Grajner Anna Niesler
Archives of Environmental Protection | 2002 | vol. 28 | No 4 | 81-88
Keywords Collapse pond Rotifera biodiversity Trophy water pollution
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Abstract

From March to November 2000 planctonic Rotifera of the collapse pond Bojszowy - Jedlina were studied. Rich fauna of Rotifera (71 taxons) was recorded. One new for Silesia Region species Erignatha clastopis (Gosse) was found. The qualitative composition of the Rotifera community in that pond differed from other investigated collapse ponds. In spite of high eutrophy domination and constance structure indicated staid character of the Rotifera community in the Bojszowy - Jedlina pond.
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Authors and Affiliations

Irena Bielańska-Grajner
Anna Niesler

Evaluation of Collapsibility of Selected Core Systems

T. Obzina V. Merta J. Rygel P. Lichý K. Drobíková
Archives of Foundry Engineering | 2022 | vol. 22 | No 1 | 48-52 | DOI: 10.24425/afe.2022.140216
Keywords Foundry Foundry cores De-coring Knocking-out Collapsibility
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Abstract

There are mainly two different ways of producing sand cores in the industry. The most used is the shooting moulding process. A mixture of sand and binder is injected by compressed air into a cavity (core), where it is then thermally or chemically cured. Another relatively new method of manufacturing cores is the use of 3D printing. The principle is based on the method of local curing of the sand bed. The ability to destroy sand cores after casting can be evaluated by means of tests that are carried out directly on the test core. In most cases, the core is thermally degraded and the mechanical properties before and after thermal exposure are measured. Another possible way to determine the collapsibility of core mixtures can be performed on test castings, where a specific casting is designed for different binder systems. The residual strength is measured by subsequent shake-out or knock-out tests. In this paper, attention will be paid to the collapsibility of core mixtures in aluminium castings.
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Bibliography

[1] Dietert, H.W. (1950). Core knock-out, in Foundry Core Practice, 2nd ed. Chicago: American Foundrymen’s Society.
[2] Jorstad, J.L. (2008). Expendable-mold casting processes with permanent patterns, in ASM Handbook Vol. 15 Casting, 10th ed. ASM International
[3] Almaghariz, E.S., Conner, B.P., Lenner, L., Gullapalli, R., Manogharan, G.P. (2016). Quantifying the role of part design complexity in using 3D sand printing for molds and cores. International Journal of Metalcasting. 10, 240-252. DOI: 10.1007/s40962-016-0027-5.
[4] Vykoukal, M., Burian, A., Přerovská, M., Bajer, T., Beňo, J. (2019). Gas evolution of GEOPOL® W sand mixture and comparison with organic binders. Archives of Foundry Engineering. 19(2), 49-54.
[5] Steinhäuser, T. (2017). Inorganic binders-Benefits, State of the art, Actual use. In World Cast in Africa, Innovative for Sustainability, Proceedings of the South African Metal Casting Conference, Johannesburg, South Africa, 13–17 March 2017; WFO: Johannesburg, South Africa, p. 26
[6] Ramrattan, S. (2019). Evaluating a ceramic resin-coated sand for aluminum and iron castings. International Journal of Metalcasting. 13(3), 519-527. DOI: https://doi.org/10.1007/s40962-018-0269-5
[7] Ettemeyer, F., Schweinefuß, M., Lechner, P., Stahl, J., Greß, T., Kaindl, J., Durach, L., Volk, W. & Günther, D. (2021). Characterisation of the decoring behaviour of inorganically bound cast-in sand cores for light metal casting. Journal of Materials Processing Technology. 296, 117201, ISSN 0924-0136. DOI: https://doi.org/10.1016/j.jmatprotec.2021. 117201.
[8] Dobosz, P., Jelínek, K., Major-Gabryś, K. (2011). Development tendencies of moulding and core sands. China Foundry. 8, 438-446.

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Authors and Affiliations

T. Obzina
1
V. Merta
1
ORCID: ORCID
J. Rygel
1
P. Lichý
1
ORCID: ORCID
K. Drobíková
1
  1. VSB - Technical University of Ostrava, Czech Republic

Area collapse algorithm computing new curve of 2D geometric objects

Michał Mateusz Buczek
Geodesy and Cartography | 2017 | vol. 66 | No 1 | DOI: 10.1515/geocart-2017-0004
Keywords shape analysis Polygon collapse medial axis geometry processing spatial database
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Abstract

The processing of cartographic data demands human involvement. Up-to-date algorithms try to automate a part of this process. The goal is to obtain a digital model, or additional information about shape and topology of input geometric objects. A topological skeleton is one of the most important tools in the branch of science called shape analysis. It represents topological and geometrical characteristics of input data. Its plot depends on using algorithms such as medial axis, skeletonization, erosion, thinning, area collapse and many others. Area collapse, also known as dimension change, replaces input data with lower-dimensional geometric objects like, for example, a polygon with a polygonal chain, a line segment with a point. The goal of this paper is to introduce a new algorithm for the automatic calculation of polygonal chains representing a 2D polygon. The output is entirely contained within the area of the input polygon, and it has a linear plot without branches. The computational process is automatic and repeatable. The requirements of input data are discussed. The author analyzes results based on the method of computing ends of output polygonal chains. Additional methods to improve results are explored. The algorithm was tested on real-world cartographic data received from BDOT/GESUT databases, and on point clouds from laser scanning. An implementation for computing hatching of embankment is described.
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Authors and Affiliations

Michał Mateusz Buczek

The Role of Acid Hardener on the Hardening Characteristics, Collapsibility Performance, and Benchlife of the Warm-Box Sand Cores

I. Budavári H. Hudák G. Fegyverneki
Archives of Foundry Engineering | 2023 | vol. 23 | No 1 | 68-74 | DOI: 10.24425/afe.2023.144282
Keywords Warm-box Sand cores bending strength Collapsibility Benchlife
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Abstract

The heat-cured core-making process has been applied for over 60 years to produce molds and cores for different types of castings. The following technologies can be classified into the terminology of “heat-cured coremaking process”: croning-, hot-box -, and warm-box process. The latest technology provides good workability of core mixture, good strength properties, dimensional stability, and good knockout performance of the sand cores. Despite all its advantages, the warm-box technology is less widespread in foundries due to the cost of the high quality thermosetting resin and the maintenance cost of the core box. In this study, the influence of the acid hardener content on the hardening characteristics (bending strength), collapsibility, and the benchlife of the warm-box sand cores were investigated. From the results, it can be said, that within the investigated composition range, increasing the acid hardener content will improve the bending strength of the sand cores. The increased acid hardener content results in higher thermal stability at the beginning of the thermal exposure, and smaller residual bending strength after 15 minutes of thermal loading. The acid hardener level has little effect on the benchlife of the warm-box sand cores, although the sand core mixture is very sensitive to the combined effect of the sand temperature and dwelling time.
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Authors and Affiliations

I. Budavári
1
ORCID: ORCID
H. Hudák
1
G. Fegyverneki
1
  1. University of Miskolc, Faculty of Materials Science of Engineering, Institute of Foundry, Hungry

Development of Water-Soluble Composite Salt Sand Cores Made by a Hot-Pressed Sintering Process

Xiaona Yang Long Zhang Xing Jin Jun Hong Songlin Ran Fei Zhou
Archives of Foundry Engineering | 2023 | vol. 23 | No 3 | 51-58 | DOI: 10.24425/afe.2023.146662
Keywords Water-soluble cores Hollow composite castings Salt cores Collapsibility
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Abstract

A wide variety of water-soluble cores are widely used in hollow composite castings with internal cavities, curved channels, and undercuts. Among them, the cores made by adding binders of inorganic salts in the form of aqueous solutions have excellent solubility in water. However, excellent collapsibility is often accompanied by poor moisture absorption resistance. In this study, a water-soluble core with moderate strength and moisture absorption resistance was prepared by hot pressing and sintering the core sand mixture of sand, bentonite, and composite salts, and a tee tube specimen was cast. The experimental results showed that the cores with KCl-K2CO3 as binder could obtain strength of more than 0.9 MPa and still maintain 0.3 MPa at 80±5% relative humidity for 6 hours; the subsequent sintering process can significantly improve the resistance to moisture absorption of the hot pressed cores (0.6 MPa after 24 hours of storage at 85±5% relative humidity); the water-soluble core prepared by the post-treatment can be used to cast tee pipe castings with a smooth inner surface and no porosity defects, and it is easy to remove the core.
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Authors and Affiliations

Xiaona Yang
1
Long Zhang
1
Xing Jin
2
Jun Hong
3
Songlin Ran
2
Fei Zhou
3
  1. School of Metallurgical Engineering, Anhui University of Technology, China
  2. Anhui Province Key Laboratory of Metallurgical Engineering & Resources Recycling, Anhui University of Technology, China
  3. Technical Department, Anhui Highly Precision Casting Co., Ltd, China

Parametric Study of Geometry Effect on Response to Applied Loadings of Metallic Honeycomb Structures by Virtual Testing of Mesoscale Models

T. Sadowski D. Pietras
Archives of Metallurgy and Materials | 2018 | vol. 63 | No 2 | DOI: 10.24425/122427
Keywords virtual testing Aluminium hexagonal honeycomb compression behaviour quasi-static deformation effective elastic property buckling collapse
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Abstract

In this paper were conducted virtual tests to assess the impact of geometry changes on the response of metallic hexagonal honeycomb structures to applied loadings. The lateral compressive stress state was taken into consideration. The material properties used to build numerical models were assessed in laboratory tests of aluminium alloy 7075. The modelling at meso-scale level allow to comprehensive study of honeycomb internal structure. The changes of honeycomb geometry elements such as: fillets radius of the cell edges in the vicinity of hexagonal vertexes, wall thickness were considered. The computations were conducted by using finite element method with application of the ABAQUS finite element method environment. Elaborated numerical models allowed to demonstrate sensitivity of honeycomb structures damage process response to geometry element changes. They are a proper tools to perform optimization of the honeycomb structures. They will be also helpful in designing process of modern constructions build up of the considered composite constituents in various branches of industry. Moreover, the obtained results can be used as a guide for engineers. Conducted virtual tests lead to conclusion that simplification of the models of internal honeycomb structure which have become commonplace among both engineers and scientist can lead to inaccurate results.
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Authors and Affiliations

T. Sadowski
D. Pietras

Resistance to Progressive Collapse Performance Analysis of Steel Open-Web Sandwich Plate Structure

Weiyi Zeng Jie Luo Jianchun Xiao
Archives of Civil Engineering | Vol. 66 | No 3 | 281-303 | DOI: 10.24425/ace.2020.134398
Keywords sensitivity analysis rod failure steel open-web sandwich plate structure progressive collapse redundancy index
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Abstract

In order to investigate the progressive collapse performance of steel open-web sandwich plate structure, the sensitivity index and the importance coefficient of the bars are analyzed by the alternate path method. The condition that the model has perimeter supports with different parameters shows the result that: the redundancy index of structure increases at the structural edge, and the redundancy index will be reduced to changing degrees at the middle structure, when the stiffness of higher ribs increases. The redundancy index has little change, when the stiffness of lower ribs or shear keys increases. The sensitivity index of the shear keys dropped significantly, but the sensitivity index of the higher ribs and lower ribs increase, when the span to depth ratio increases. The sensitivity index of the higher ribs in L1 line increases significantly, when the span to depth ratio declines. So it is advisable to strengthen the higher ribs to avoid excessive sensitivity of ribs, when the span to depth ratio declines.

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Authors and Affiliations

Weiyi Zeng
Jie Luo
Jianchun Xiao

INTERMEDIATE BRONZE AGE IN SOUTHERN LEVANT(4200–4000 BP) – WHY DID FOUR CITIES IN TRANSJORDAN SURVIVE URBAN COLLAPSE?

Michał E. Bieniada
Studia Quaternaria | 2016 | Vol. 33 | Iss. 1
Keywords Palestine 4200 BP collapse of urbanism Intermediate Bronze Age climatic niche in Transjordan influence of Dead Sea
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Authors and Affiliations

Michał E. Bieniada

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