The carbon budget of the Baltic Sea

This paper presents the results of a comprehensive study of the Baltic Sea carbon budget. The Baltic Sea is very much influenced by terrestrial carbon input. Rivers are the largest carbon source, and their input amounts to 10.90 Tg C yr<sup>−1</sup> (Tg = 10<sup>12</sup> g) with a 37.5% contribution of organic carbon. On the other hand, carbon is effectively exported from the Baltic to the North Sea (7.67 Tg C yr<sup>−1</sup>) and is also buried in bottom sediments (2.73 Tg C yr<sup>−1</sup>). The other sources and sinks of carbon are of minor importance. The net CO<sub>2</sub> emission (1.05 Tg C yr<sup>−1</sup>) from the Baltic to the atmosphere was calculated as the closing term of the carbon budget presented here. There is a net loss of organic carbon, which indicates that the Baltic Sea is heterotrophic

Elastic waves : selected issues

W artykule zaprezentowano i omówiono wybrane rodzaje występujących w przyrodzie fal, tj. fal słabej nieciągłości oraz fal silnej nieciągłości (tzw. fale uderzeniowe). Ponadto w pracy przedstawiono możliwe zastosowanie opisanych fal, jak również dokonano przeglądu literaturowego ze wskazaniem prac, w których wykorzystuje się metodę elementów skończonych do walidacji opisów matematycznych i wyników badań prezentowanych fal.In this paper there are presented and discussed two different naturally occurring wave types i.e. low discontinuity waves and strong discontinuity waves called impact waves. Moreover, in this paper there are presented possible applications of described waves and a small literature overview has been performed indicating the works, where finite element method is used to validate the mathematical problem descriptions and the experimental results of presented wave types

Comparative analysis of displacements and stress calculated in computer programs supporting design of building

W artykule przedstawiono analizę porównawczą przemieszczeń i naprężeń obliczonych przy użyciu programów opartych na metodzie elementów skończonych: ADINA oraz Autodesk ROBOT Structural Analysis. Do obliczeń numerycznych przyjęto jednostronnie utwierdzoną belkę stalową o skrzynkowym przekroju poprzecznym (kształtownik zamknięty prostokątny wg PN-EN 10210-2:2000) z zaokrąglonymi krawędziami zewnętrznymi oraz wewnętrznymi. Obliczenia zostały wykonane w przestrzeni trójwymiarowej (3D), a otrzymane wyniki omówione w podsumowaniu.This paper through the comparative analysis of displacement and stress results broaches the subject of computer aided design software for building structures. In the analysis there were used commonly used programs like ADINA and Autodesk ROBOT Structural Analysis, which are based on finite element method. In both programs one end of cantilever beam was modeled as a steel box with rounded edges. Dimensions of the beam were 140x80x5 mm. Loads acting on the beam were: dead load, concentrated moment acting in longitudinal cutting plane and concentrated force acting in oblique direction to the cross-section cutting plane. Calculations by above-mentioned programs were done in three-dimensional space (3D). Received results showed differences, which took place by using those two programs and next in this paper causes of those differences were discussed. Selected computation model, which is box profile with rounded external and internal edges, allowed to indicate limitations of the programs. In the essential part of this paper dedicated to computer aided design an example and computation models were shown as figures. Received results were put into tables, which allows to compare differences in obtained values. In sum-up obtained results of stress and displacement were discussed. Moreover, there were discussed limitations in programs encountered at modeling, finite element method nets types and their influence on results using FEM

Człowiek, środowisko, narzędzia - podstawy oceny ergonomicznej i działań polepszających warunki pracy

Ergonomia to dziedzina nauki zajmujaca się relacjami pomiędzy człowiekiem i jego materialnym otoczeniem, której celem jest - najogólniej rzecz ujmując - optymalne dopasowanie przestrzeni i przedmiotów do naszych potrzeb

A Fast Method of Identifying Rechargeable Batteries Condition and Defects

The paper presents fast method of identifying industrial and general use rechargeable batteries condition and defects exemplary lithium-ion cells. The proposed method is based on measuring a internal battery electrical impedance for selected frequency points and the next the results are compare with reference characteristics. Diagnostic process is performed for a few minutes when the battery is charging or discharging. So far used, the most popular methods require controlled charging and discharging cells to determine approximately of their capacity and need a long time of the diagnostic process (about few hours to over a dozen hours). The new method allows the dramatically reduction of measurement time and in effect reduces financial work costs of service. The paper shows a various setup systems with commonly use RLC impedance bridges were used in the research. The analysis of measurements allowed to determine the specific spectral function, which indicates rechargeable battery condition. Moreover, it is also possible to apply the obtain method to another electrochemical cell type

Non-linear vibrations of a non-uniform beam with symmetrically located piezoelectric patches

In this paper the non-linear vibration behaviour and its modification due to the piezoelectric actuation of a beam with varying cross section and resting on an elastic foundation has been discussed. Due to assumed end conditions the stretching force emerges during the system vibrations. That force can be modified by an axial residual force to enhance or reduce the value of vibrations frequency of the beam. The system is divided onto three segments with the central segment consisted of the core beam and two colocally and perfectly bonded piezo patches. In order to obtain the approximate solutions of the non-linear frequency of the systems the Lindstedt-Poincare method has been utilized. Vast number of numerical results shows that not only the structural parameters of the system have significant effect on its non-linear vibration behaviour at a given amplitude but also the residual force and the elastic foundation modulus

Connections in composite steel concrete structures : review of utilized solutions

W artykule zaprezentowano historyczne i współczesne stosowane rozwiązania połączeń w konstrukcjach zespolonych stalowo-betonowych. Dodatkowo w pracy omówiono wymagania, jakie współcześnie muszą spełniać łączniki mechaniczne.In this paper there were shown historical and present utilized solutions of connections in composite steel-concrete structures. Moreover, current requirements for bolts in accordance with European Eurocode have been presented

Buckling of stepped beams resting on an elastic foundation

The influence of structural parameters of a stepped beam with two ends fixed and resting on Winkler foundation on its buckling critical force has been discussed in this paper. The structure inhomogeneity results from two piezoceramic plates perfectly bonded at the top and bottom surface of the beam. For the performed analysis five different supports of beam ends which prevent longitudinal displacements have been adopted. Numerical analysis has been divided into two parts. The first part concerns the influence of the system geometry on its critical force, whereas in the second part, a modification of the buckling load resulting from the electric field applied to the piezosegment has been investigated