The standard PN-EN_1993-1-5:_2008 (Eurocode 3) compared with the standard (PN-B-03200:_1990) used previously in Poland, introduces extended rules referring to the computations of the bearing capacity of the plated structural elements including the shear lag effect. The stress distribution in the width flanges is variable. Therefore in the case of the beam with the shear lag effect cannot be calculated by the classic beam theory.

In this article a comparison of the results of the calculations of forces distribution, stresses and displacement according to the rule presented in PN-EN_1993 and results of the numerical computations for_3D model (using finite element method) is presented. The elastic shear lag effects, the elastic shear lag effects including effects of the plate buckling and the elastic-plastic shear lag effects including the local instabilities were analysed. The calculations were performed for beams with a small and a large span and an influence of stiffeners was analysed.

Prof. Michał Kowal (National Centre for Nuclear Research, NCBJ) talks about the complexities of theoretical work, long-lived and excited nuclear states, and the frontier of our knowledge about superheavy atomic nuclei.

The research involved coal from 11 coal mines in the USCB in Poland, intended for combustion in power plants and for home furnaces. It has been stated that the content of As, Cd, Co, Cr, Cu, Mo, Ni, Pb, Sb and Zn in the ash of coal fines from the USCB with a density of <1.30 × 103 kg/m3 is the largest, and in the ash fraction with a density >2.00 × 103 kg/m3 is the smallest The fraction ash of coal fine with a density> 2.00 × 103 kg/m3 has the greatest impact on the content of As, Cd, Co, Cr, Mo, Pb and Zn in whole coal fines from the USCB. In turn, the largest impact on the content of Cu, Ni and Sb in whole fine coal ash has the fraction of coal fine having a density of 1.60–2.00 × 103 kg/m3 (for Cu) and fraction with a density <1.35 × 103 kg/m3 (Ni and Sb). The main carriers of elements in fine coal ash, thus in future furnace waste, are the grains of aluminosilicates and iron oxides resulting from the combustion of probably fusinite and semifusinite and the combustion of adhesions of these macerals with dolomite, ankerite and pyrite. The purification of fine coal from the matter with a density >2.00 × 103 kg/m3 may reduce the sulfur content (by 40%), the content of main element oxides (from 33% to 85%) and the content of ecotoxic elements (from 7% to 59%) in fine coal ash, i.e. in potential furnace wastes. Due to the small content of mineral matter, ash and sulfur in coal, small content of Al, Fe, Ca, Mg, Na, K, P oxides and high content of SiO2 in coal ash, low value of the Rogi sinterability index, small inclination of coal fine to slag the furnaces and boiler fouling by sludge, the investigated coal was favorable for technological reasons, fuel in power plants and for home furnaces

The present work focuses on the modeling and analysis of mechanical properties of structural steel. The effect of major alloying elements

namely carbon, manganese and silicon has been investigated on mechanical properties of structural steel. Design of experiments is used to

develop linear models for the responses namely Yield strength, Ultimate tensile strength and Elongation. The experiments have been

conducted as per the full factorial design where all process variables are set at two levels. The main effect plots showed that the alloying

elements Manganese and Silicon have positive contribution on Ultimate tensile strength and Yield strength. However, Carbon and

Manganese showed more contribution as compared to Silicon. All three alloying elements are found to have negative contribution

towards the response- Elongation. The present work is found to be useful to control the mechanical properties of structural steel by varying

the major alloying elements. Minitab software has been used for statistical analysis. The linear regression models have been tested for the

statistical adequacy by utilizing ANOVA and statistical significance test. Further, the prediction capability of the developed models is

tested with the help of test cases. It is found that all linear regression models are found to be statistically adequate with good prediction

capability. The work is useful to foundrymen to choose alloying elements composition to get desirable mechanical properties.

The present paper is dedicated to presentation and energy verification of the methods of stabilization the strain energy by penalty coefficients. Verification of the methods is based on the consistency and ellipticity conditions to be satisfied by the finite elements. Three methods of stabilization are discussed. The first does not satisfy the above requirements. The second is consistent but cannot eliminate parasitic energy terms. The third method, proposed by the author, is based on the decomposition of the element stiffness matrix. The method can help to eliminate locking of the finite elements. For two-noded beam element with linear shape functions and exact integration a stabilized free of locking (and elliptical) element is received (equivalent to reduced integration element). Two plate finite elements are analyzed: four-noded rectangular element and DSG triangle. A new method of stabilization with the use of four independent parameters is proposed. The finite elements with this kind of stabilization satisfy the consistency condition. In the rectangular element it was not possible to eliminate one parasitic term of energy which appears during the procedure. For DSG triangle all parasitic terms of energy are eliminated. The penalty coefficients depends on the geometry of the triangle.

A numerical analysis of the initially clamped bolt joint subject to the working pressure is presented in the paper. Special, hexahedral 21- and 28-node isoparametric finite elements have been employed to model the contact zone. In this model, one takes into account loading due to the working pressure in the gap between the gasket and the flange arising as an effect of the progressing joint opening, what has not been considered in recent papers. Nonlinear stiffness characteristics of the bolt and the flange with the gasket are developed. Working pressure corresponding to the critical bolt force resulting in the joint leakage (complete opening between the gasket and the flange) is determined. FE computational results are compared with the available experimental results. The numerical results are presented using the authors' own graphical postprocessor.

In the paper, a mechanical set composed of a robot (manipulator) and of an elastic beam is considered. The beam is fixed to the top of the robot structure. In most of similar cases, undesired vibrations can be excited in the beam. They create an especially significant problem when dynamics in the robot braking period is examined. In the paper, estimation and modification of length of the braking period is proposed, in order to reduce the undesired vibrations. Investigations are restricted to numerical models, only. The rigid finite elements modelling and the multibody modelling are used together to obtain the numerical model required for the system. Instead of the classical rigid finite elements, its modified version is used, where some of the relative deformations are locked between the neighbour elements. As a result, sizes of the obtained matrices can be reduced as well as the time of the numerical calculations.

The determination of the content of ecotoxic elements directly in flue gas is important for determining its actual emission from coal combustion. Moreover, in the BAT for large combustion plants conclusions adopted in 2017, apart from tightening of pollutants emission standards, i.e. SO 2, NO x and dusts, and setting emission limits, among others, for mercury, the monitoring of the actual emission of toxic elements has been established with the use of specific analytical methods. The review and comparison of available methods of analyzing the content of elements in flue gases in accordance with American and European standards has been presented in the article. Moreover, the factors influencing the quality of the obtained measurement results were identified.

The potential of five plants namely Atriplex halimus L., A. canescens (Pursh) Nutt., Suaeda fruticosa (Forssk. ex J.F. Gmel.), Marrubium vulgare L. and Dittrichia viscosa (L.) Greuter from two selected wetlands in northwest Algeria subjected to house and industrial effluents were examined to assess their arbuscular mycorrhizal fungal (AMF) diversity and colonization, as well as to determine their tolerance and ability in accumulating metallic trace elements (MTEs). The purpose was to investigate whether, or not, these fungi are related to metallic uptake. Arbuscular mycorrhizal association was observed in all plant species, since the dual association between AMF and dark septate endophytes (DSE) was found in roots of 80% plants species. Hence, the decreasing trend of metal accumulation in most plant organs was Zn>Cu>Pb, and the most effi cient species were M. vulgare> S. fruticosa> A. canescens> D. viscosa> A. halimus. The bioaccumulator factors exceeded the critical value (1.0) and the transport factors indicated that all these species were phytoremediators. Pearson correlation showed that Cd bioaccumulation and translocation were inhibited by AMF infection; meanwhile Zn, Pb and Cd accumulation were affected by AMF spore density and species richness, DSE frequency, pH, AMF and plant host. Native halophytes showed a multi-metallic resistance capacity in polluted wetlands. M. vulgare was the most efficient in metal accumulation and the best host for mycorrhizal fungi. AMF played a major role in metal accumulation and translocation.

Red basil (Ocimum basilicum L.) cv. Red Rubin was cultivated in model pot experiment in the soil amended by arsenic, cadmium and lead solutions in stepwise concentrations representing the soil concentration levels of former mining area in the vicinity of Příbram, Czech Republic. The element levels added to the soil reached up to 40 mg Cd, 100 mg As, and 2000 mg Pb per kg of soil. Moreover, essential macro-and microelements as well as cyanidine contents were investigated to assess their potential interactions with the risk elements. The extractable element portions in soils determined at the end of vegetation period differed according to the individual elements. Whereas the plant-available (extractable with 0.11M CH3COOH) content of Cd represented 70-100% of the added Cd, the mobile portion of Pb did not exceed 1%. The risk element content in plants reflected the increasing element contents in soil. The dominant element portions remained in plant roots indicating the limited translocation ability of risk elements to the aboveground biomass of this plant species. Although the risk element contents in amended plants significantly increased, no visible symptoms of phytotoxicity occurred. However, the effect of enhanced risk element contents on the essential element uptake was assessed. Considering inter-element relationships, elevated sulphur levels were seen in amended plants, indicating its possible role of phytochelatin synthesis in the plants. Moreover, the molybdenum contents in plant biomass dropped down with increasing risk element uptake by plants confirming As-Mo and Cd-Mo antagonism. The increasing content of cyanidine in the plant biomass confirmed possible role of anthocyanins in detoxification mechanism of risk element contaminated plants and suggested the importance of anthocyanin pigments for risk element tolerance of plants growing in contaminated areas.

Laboratory and field experiments have been conducted to study mobility of chromium and lead in

floodplain sediments. The main goal of the research was to verify a hypothesis whether changes of chromium

and lead concentration could be used to estimate the relative age of floodplain deposits. The basis for undertaking such research was the presence of weaving industry centers in the Obra River valley between the 16th and

the 19th century and using Cr and Pb compounds in paint recipes. The Cr and Pb contents were also analyzed in

three vertical profiles unaffected by the field experiments. The age of organic sediments in each of the profiles

was determined using the radiocarbon analysis. The results of the laboratory experiments have shown that the

highest contents of the elements were noted in the surface layer of the sediments placed in the column. However,

the contents decreased during the last phase of the experiments and both vertical and horizontal migration of

both elements was observed. A more intensive mobility was observed in the field test. Its cause could be the

changes of the groundwater level, floodplain inundation and pH conditions in alluvial deposits. Such processes

may have influenced migration of the compounds originating from the weaving industry production; Cr and Pb

contents detected in the profiles unaffected by the field experiment were too small to be used for relative dating of alluvial deposits. Moreover, the alluvial deposits with increased contents of the studied elements may be

older than the period of the weaving industry development. Cr and Pb mobility was especially intensive in the

profiles situated within the near bed zone of the floodplain due to regular inundation, and the activity of erosion

and accumulation processes entraining the studied elements back to transport in the river bed.

This paper aims at providing a framework for comprehensive steady-state time-domain analysis of rotating machines considering motion. The steady-state waveforms of electromagnetic and circuit quantities are computed via iterative solution of the nonlinear field-circuit-and-motion problem with constraints of time periodicity. The cases with forced speed and forced load torque are considered. A comparison of execution times with a conventional time-stepping transient model is carried out for two different machines. The numerical stability of a time-periodic model with forced speed is shown to be worse than that of traditional transient time-stepping one, although the model converges within a reasonable number of iterations. This is not the case if forced load via equation of mechanical balance is accounted for. To ensure convergence of the iterative process the physical equation of motion is replaced by the fixed-point equation. In this way the model delivers time-periodic solutions regarding not only the electromagnetic quantities but also the rotational speed.

The results of some mechanical properties of four Mg-5Al-xRE-0.4Mn (x = 1 – 5) alloys are presented. The microstructure of

experimental alloys consisted of an α-Mg phase and an α+γ semi-divorced eutectic, Al11RE3 phase and an Al10RE2Mn7 intermetallic

compound. For gravity casting in metal mould alloys, Brinell hardness, impact strength, tensile and compression properties at ambient

temperature were determined. The performed mechanical tests allowed the author to determine the proportional influence of the mass

fraction of rare earth elements in the alloys on their tensile strength, yield strength, compression strength and Brinell hardness. The

impact strength of the alloys slightly decreases with a rise in the rare earth elements mass fraction.

The paper presents an analysis of the effect of shape of primary silicon crystals on the sizes of stresses and deformations in a surface layer

of A390.0 alloy by Finite Elements Method (FEM). Analysis of stereological characteristics of the studied alloy, performed based on a

quantitative metallographic analysis in combination with a statistical analysis, was used for this purpose. The presented simulation tests

showed not only the deposition depth of maximum stresses and strains, but also allowed for determining the aforementioned values

depending on the shape of the silicon crystals. The studied material is intended for pistons of internal combustion engines, therefore the

analysis of the surface layer corresponded to conditions during friction in a piston-cylinder system of an internal combustion engine having

power of up to 100 kW. The obtained results showed important differences in the values of stresses and strains up to 15% between various

shape of the silicon crystals. Crystals with sharp edges caused higher stresses and deformation locally than those with rounded shapes.

Magnesium alloy with 5 wt% Al, 0.35 wt% Mn and 5 wt% rare earth elements (RE) was prepared and gravity cast into a sand mould.

Microstructure investigations were conducted. Analyses of the Mg-Al-RE alloy microstructure were carried out by light microscopy,

scanning electron microscopy and the XRD technique. In the as-cast condition, the alloy was composed of α-Mg, Al11RE3 and

Al10RE2Mn7 intermetallic phases. Additionally, due to non-equilibrium solidification conditions, an Al2RE intermetallic phase was

revealed.

The modification of the chemical composition of non-metallic inclusions by rare-earth elements in the new-developed microalloyed steels was discussed in the paper. The investigated steels are assigned to production of forged elements by thermomechanical treatment. The steels were melted in a vaccum induction furnace and modification of non-metallic inclusions was carried out by the michmetal in the amount of 2.0 g per 1 kg of steel. It was found that using material charge of high purity and a realization of metallurgical process in vacuous conditions result in a low concentration of sulfur (0.004%), phosphorus (from 0.006 to 0.008%) and oxygen (6 ppm). The high metallurgical purity is confirmed by a small fraction of non-metallic inclusions averaging 0.075%. A large majority of non-metallic inclusions are fine, globular oxide-sulfide or sulfide particles with a mean size 17 µm2 . The chemical composition and morphology of non-metallic inclusions was modified by Ce, La and Nd, what results a small deformability of nonmetallic inclusions during hot-working.

The paper presents the methodology that makes it possible to evaluate computational model and introduce current corrections to it. The methodology ensures proper interpretation of nonlinear results of numerical analyses of thin-walled structures. The suggested methodology is based on carrying out, in parallel to nonlinear numerical analysis, experimental research on some selected crucial zones of loadcarrying structures. Attention is drawn to the determinants concerning the performance of an adequate experiment. The author points out on indicating the role of model tests as a fast and economically justified research instruments practicable when designing thin-walled load-carrying structures.

The presented considerations are illustrated by an example of a structure whose geometrical complexity and ranges of deformation are characteristic for modern solutions applied in the load-carrying structures of airframes. As the representative example, one selected the area of the load-carrying structure that contains an extensive cut-out, in which the highest levels and stress gradients occur in the conditions of torsion evoking the post-buckling states within the permissible loads. The stress distributions within these ranges of deformations were used as the basis for determining the fatigue life of the structure.