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Abstract

The thermal, anemometric and bioclimatic conditions on the topoclimatic scale were investigated in the summer season in the EbbaValley region in central Spitsbergen. Eight measurement sites, representing different ecosystems and different types of active surfaces typical of Spitsbergen, were chosen and automatic, hourly recorded, measurements were per− formed at the sites between 11 and 25 of July 2009. The analysis of the spatial distribution of the air temperature and thewind−chill temperature, both for the dayswith radiation and non−ra− diation weather, indicates that the most favorable regions in the interior of Spitsbergen are those situated in the shielded central parts of the valleys and in the lower parts of the slopes with southern exposure. The thermal and wind conditions are definitely less favorable at the tops of elevations and on the glacier. Large differences between the air temperature and the wind−chill temperature were noted, particularly during the unfavorable non−radiation weather, on the glacier and on open peaks due to a large horizontal and vertical wind−chill temperature gradient. The thermal inversions observed in the Ebba Valley in July 2009 were not of the typi− cal, glacier katabatic wind origin. They appeared during the western air circulation, which brings advection of cooled air from above the cold waters of Petunia Bay. The cold air pene− trates into the valley and pushes upwards themass of warmer air in the valley, creating a rather thin inversion layer, whose upper edge is marked with thin Stratus clouds.
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Abstract

In modern times, there are increasing requirements for products quality in every part of manufacturing industry and in foundry industry it is not different. That is why a lot of foundries are researching, how to effectively produce castings with high quality. This article is dealing with search of the influence of using different types of risers or chills on shrinkage cavity production in ductile iron castings. Differently shaped risers were designed using the Wlodawer´s modulus method and test castings were poured with and without combination of chills. Efficiency of used risers and chills was established by the area of created shrinkage cavity using the ultrasound nondestructive method. There are introduced the production process of test castings and results of ultrasound nondestructive reflective method. The object of this work is to determine an optimal type of riser or chill for given test casting in order to not use overrated risers and thus increase the cost effectiveness of the ductile iron castings production.
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Abstract

The article is a case study of the steel milling ring casting of about 6 tonnes net weight. The casting has been cast in the steel foundry the authors have been cooperating with. The aim was to analyse the influence of the shape of the chills and the material which was used to make them on the casting crystallization process. To optimally design the chills the set of the computer simulation has been carried out with 3 chills’ shape versions and 3 material’s versions and the results have been compared with the technology being in use (no chills). The proposed chills were of different thermal conductivity from low to high. Their shapes were obviously dependant on the adjacent casting surface geometry but were the result of the attempt to optimise their effect with the minimum weight, too. The chills working efficiency was analysed jointly with the previously designed top feeders system. The following parameters have been chosen to compare their effectiveness and the crystallization process: time to complete solidification and so-called fed volume describing the casting feeding efficiency. The computer simulations have been carried out with use of MagmaSoft v. 5.2 software. Finally, the optimisation has led to 15% better steel yield thanks to 60% top feeders weight reduction and 40% shorter solidification time. The steel ring cast with use of such technology fulfil all quality criteria.
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