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  • Author: Ivan Němec x
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PARAMETRIC STUDY OF THE STRUCTURAL RESPONSE OF NPP CONTAINMENT TO IMPACT LOADING

Abstract

The presented article is a contribution to the discussion concerning nuclear safety which has intensified after the Fukushima Daiichi nuclear disaster. A parametric study concerning various materials, containment wall thicknesses and different aircraft speeds at the time of impact was performed. The aim of this study was to establish damage extent of various variants of a containment structure. Containment damage was evaluated by means of the value of maximum permanent deformation and plastic strain extent. The purpose of this study was also to foster experiential suggestions for improving the explicit method in the RFEM program in order to release it for RFEM users.

Open access
Parallel Computation on Multicore Processors Using Explicit Form of the Finite Element Method and C++ Standard Libraries

Abstract

In this paper, the form of modifications of the existing sequential code written in C or C++ programming language for the calculation of various kind of structures using the explicit form of the Finite Element Method (Dynamic Relaxation Method, Explicit Dynamics) in the NEXX system is introduced. The NEXX system is the core of engineering software NEXIS, Scia Engineer, RFEM and RENEX. It has the possibilities of multithreaded running, which can now be supported at the level of native C++ programming language using standard libraries. Thanks to the high degree of abstraction that a contemporary C++ programming language provides, a respective library created in this way can be very generalized for other purposes of usage of parallelism in computational mechanics.

Open access
DESIGN OF INITIAL SHAPE OF MEMBRANE STRUCTURES

Abstract

The subject of this article is the question of design and analysis of membrane structures. The first part of this article deals with the problem of form-finding. It is the problem of searching for the initial shape of membrane structure. In the second part of the article, an example of design and analysis of the membrane structure of a stadium roof is presented. This work was carried out with respect to the intention of companies Dlubal Software, s.r.o. and FEM consulting, s.r.o. to create the module for finding initial shapes of membrane structures, which would consequently be implemented into the software RFEM.

Open access
A New Cable-Pulley Algorithm in RFEM

Abstract

The cable-pulley system is widely used for its advantages. In this paper, application of a new algorithm for the calculation of cables on pulleys is presented. Unlike other algorithms, this algorithm enables to take the magnitude of the radius of each pulley into account. This new algorithm is implemented in the RFEM program because of its higher accuracy and efficiency. Comparison of the commonly used algorithm, which ignores pulley radius, and the new algorithm is presented.

Open access
Effects of HSQ e–beam Resist Processing on the Fabrication of ICP–RIE Etched TiO2 Nanostructures

Abstract

Patterning of metal oxide nanostructures with different shapes and well-defined size may play an important role in the improvement of MEMS systems, sensors and optical devices. We investigated the effects of HSQ e-beam resist processing on the fabrication of sputtered TiO2 nanostructures. They were patterned using direct write e-beam lithography combined with ICP-RIE etching in CF4/Ar plasma. Experimental results confirmed that the HSQ resist with a thickness of about 600 nm is suitable as a masking material for optimal etching process and allows patterning of the dots array in TiO2 sputtered films with a thickness up 150 nm. TiO2 arrays with a minimal dots diameter of 180 nm and spacing of 1000 nm were successfully developed.

Open access
Health policy in the Czech Republic: General character and selected interesting aspects

Abstract

Transformation of the health care system was a task faced by all formerly socialist Central and Eastern European countries. The years of changes revealed a large number of problems, including those induced by the limited capacity of governments to formulate and implement health care reforms. The goal of this article is to reflect the Czech situation. We start by summarizing the historical development of the Czech health care system in the context of government capacity for implementing health policy. In the core parts of this article, we highlight the main features of Czech health policy making and implementation and present an in-depth analysis of two selected country-specific issues - a low level of patient co-payments and a pluralistic insurance-based financing of health services.

Open access