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Abstract

Scientific research is activities aimed at discovering previously unknown facts, phenomena, processes, mechanisms, etc., using objective, repeatable and verifiable methods. In practice, this means that if we strive to investigate something unknown, it is impossible to precisely plan what we discover, because we do not know it. This human activity differs from all the others, where, although the goals set can be both easy and simple as well as ambitious and difficult, it is possible to precisely indicate the specific end goal of the activity that we want to achieve, specific measures that are needed for this and specific methods what we need to apply. Therefore, if we can predict what exactly is needed to achieve the assumed goals, it can be any human activity but scientific research, because its results cannot be predicted by definition. This has profound consequences, both in the conditions that must be created for the practice of science, and in the results of scientific research. This unpredictability of the results of scientific work causes that, on the one hand, many legal provisions that work well in other spheres of life, become absurd in science and inhibit its development, and on the other hand, obtaining surprising results is relatively frequent in science. Such surprises, sometimes the result of unintentional mistakes by researchers, have led to many groundbreaking discoveries. It is also important to realize that attempts to subordinate science to political goals can lead to dramatic effects, so such actions should never take place. Politicians should support scientific research, point to its enormous social role, but never indicate what the results of scientific work are to be.
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Authors and Affiliations

Grzegorz Węgrzyn
1

  1. Uniwersytet Gdański, Wydział Biologii, Katedra Biologii Molekularnej
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Abstract

Abstract The paper presents the extent of fault effects in FPGA based systems and concentrates on transient faults (induced by single event upsets - SEUs) within the configuration memory of FPGA. An original method of detailed analysis of fault effect propagation is presented. It is targeted at microprocessor based FPGA systems using the developed fault injection technique. The fault injection is performed at HDL description level of the microprocessor using special simulators and developed supplementary programs. The proposed methodology is illustrated for soft PicoBlaze microprocessor running 3 programs. The presented results reveal some problems with fault handling at the software level.
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Authors and Affiliations

Mariusz Węgrzyn
Janusz Sosnowski
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Abstract

The paper presents an approach of numerical modelling of alloy solidification in permanent mold and transient heat transport between the casting and the mold in two-dimensional space. The gap of time-dependent width called "air gap", filled with heat conducting gaseous medium is included in the model. The coefficient of thermal conductivity of the gas filling the space between the casting and the mold is small enough to introduce significant thermal resistance into the heat transport process. The mathematical model of heat transport is based on the partial differential equation of heat conduction written independently for the solidifying region and the mold. Appropriate solidification model based on the latent heat of solidification is also included in the mathematical description. These equations are supplemented by appropriate initial and boundary conditions. The formation process of air gap depends on the thermal deformations of the mold and the casting. The numerical model is based on the finite element method (FEM) with independent spatial discretization of interacting regions. It results in multi-mesh problem because the considered regions are disconnected.

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Authors and Affiliations

T. Skrzypczak
L. Sowa
E. Węgrzyn-Skrzypczak
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Abstract

Presented paper shows the mathematical and numerical approaches for modelling of binary alloy solidification solved by the Finite Element Method (FEM). The phenomenon of shrinkage cavities formation process is included in the numerical model. Multiple macroscopic cavities can be modelled within the single casting volume. Solid, liquid and gaseous phases with different material properties are taken into account during solidification process. Mathematical model uses the differential equation of heat diffusion. Modification of specific heat is used to describe the heat releasing during liquid-solid phase change. Numerical procedure of shrinkage cavities evolution is based on the recognition of non-connected liquid volumes and local shrinkage computation in the each of them. The recognition is done by the selection of sets of interconnected nodes containing liquid phase in the finite element mesh. Original computer program was developed to perform calculation process. Obtained results of temperature and shrinkage cavities distributions are presented and discussed in details.

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Authors and Affiliations

T. Skrzypczak
L. Sowa
E. Węgrzyn-Skrzypczak
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Abstract

This paper presents results of experimental research concerning the impact of an innovative method of micro-jet cooling on the padding

weld performed with MIG welding. Micro-jet cooling is a novel method patented in 2011. It enables to steer the parameters of weld

cooling in a precise manner. In addition, various elements which may e.g. enhance hardness or alter tribological properties can be entered

into its top surface, depending on the applied cooling gas. The material under study was steel 20MnCr5, which was subject to the welding

process with micro-jet cooling and without cooling. Nitrogen was used as a cooling gas. The main parameter of weld assessment was wear

intensity. The tests were conducted in a tribological pin-on-disc type position. The following results exhibit growth at approximately 5% in

wear resistance of padding welds with micro-jet cooling.

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Authors and Affiliations

T. Węgrzyn
W. Tarasiuk
J. Piwnik
D. Sieteski

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