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Open access

M. Dacko and R. Brodzik

Abstract

The article presents numerical analysis of the portion of concrete airport pavement that consists of two concrete panels connected with dowels, subjected to thermal and service loads, in terms of changes in base rigidity, plate thickness and diameters, and spacing of dowels. Modifications of the thickness of the plates, diameter and spacing of dowels, and base rigidity were considered by assessing the level of stress and displacement in the analysed concrete plate, as well as normal and tangential stresses in dowels by using finite element method. On the basis of an analysis of examples, an optimal solution of dowelling connections in concrete plates with established loads was proposed. The results of the calculations were presented as a contour level distributions and comparison tables.

Open access

M. Iwańska, A. Oleksy, M. Dacko, B. Skowera, T. Oleksiak and E. Wójcik-Gront

Summary

Wheat is one of the modern world’s staple food sources. Its production requires good environmental conditions, which are not always available. However, agricultural practices may mitigate the effects of unfavorable weather or poor-quality soils. The influence of environmental and crop management variables on yield can be evaluated only based on representative long-term data collected on farms through well-prepared surveys.The authors of this work analyzed variation in winter wheat yield among 3868 fields in western and eastern Poland for 12 years, as dependent on both soil/weather and crop management factors, using the classification and regression tree (CART) method. The most important crop management deficiencies which may cause low wheat yields are insufficient use of fungicides, phosphorus deficiency, non-optimal date of sowing, poor quality of seeds, failure to apply herbicides, lack of crop rotation, and use of cultivars of unknown origin not suitable for the region. Environmental variables of great importance for the obtaining of high yields include large farm size (10 ha or larger) and good-quality soils with stable pH. This study makes it possible to propose strategies supporting more effective winter wheat production based on the identification of characteristics that are crucial for wheat cultivation in a given region.