FEM analysis of hollow hub forming in rolling extrusion process

In this paper are presented the results of numerical calculations of rolling extrusion process of a hollow hub. As the flanges manufacturing at both sides of the product is required, in the analyzed process of rolling extrusion, a rear bumper was implemented as additional tool limiting axial metal flow. Numerical calculations of the hub forming process were conducted basing on finite element method, applying software Deform3D and Simufact in conditions of three dimensional state of strain. The obtained satisfactory results show that it is possible to conduct the further research works of experimental character, with the application of a modernized aggregate for the rolling extrusion process PO-2

FEM analysis of hollow hub forming in rolling extrusion process

In this paper are presented the results of numerical calculations of rolling extrusion process of a hollow hub. As the flanges manufacturing at both sides of the product is required, in the analyzed process of rolling extrusion, a rear bumper was implemented as additional tool limiting axial metal flow. Numerical calculations of the hub forming process were conducted basing on finite element method, applying software Deform3D and Simufact in conditions of three dimensional state of strain. The obtained satisfactory results show that it is possible to conduct the further research works of experimental character, with the application of a modernized aggregate for the rolling extrusion process PO-2

Atmospheric Computations to Assess Acidification in Europe: Work in Process

This Research Report contains extended summaries of papers presented at an international technical meeting on atmospheric computations held in Warsaw, September, 1985. The topics discussed include uncertainty analysis of long-range transport models, the current status of selected long-range transport models of particular relevance to policy analysis, and technical problems associated with the linkage of air pollution and ecological models

An Approach to Uncertainty of a Long Range Air Pollutant Transport Model

This paper presents a preliminary framework for analyzing uncertainty of a long range air pollutant transport model. This framework was used to assess EMEP model uncertainty. The uncertainty problem is defined in a decision-making context and a distinction is made between uncertainty analysis, sensitivity analysis, and model calibration/verification. A taxonomy is introduced to organize uncertainty sources. The taxonomy includes: model structure, parameters, forcing functions, initial state and model operation. These categories are further subdivided into diagnostic and forecasting components. To limit the number of uncertainties for quantitative evaluation, some uncertainties are "screened". Methods are introduced to evaluate uncertainties. These include (1) Monte Carlo simulation of composite parameter, forcing function and initial state uncertainties, and (2) statistical analysis of EMEP source-receptor matrices. Preliminary results of applying this methodology to the EMEP model are presented

Nitrogen Deposition Calculations for Europe

Nitrogen deposition calculations for Europe were performed by separate models describing the long range transport of ammonia and oxidized nitrogen. Tests of model results against observations are briefly described. Nitrogen deposition was computed for several NOx emissions reduction scenarios. These reductions were adapted from an OECD study and applied to the 27 largest countries in Europe. They do not refer to a particular target year. A "Maximum feasible NOx emissions reduction" scenario reduced overall European emissions by 62% relative to 1980 emissions. Other scenarios, such as point source reduction or traffic limits, reduced European emissions by 9-35%. Most reduction scenarios affected the pattern of NOx-nitrogen deposition, but did not change very much the overall pattern of total (NOx plus NHx) nitrogen deposition. Depending on the desired level of environmental protection, it may be necessary to reduce ammonia emissions in addition to NOx emissions in order to reduce nitrogen deposition in Europe

Heavy Metals Contamination in Eastern Europe: Background Load from the Atmosphere

In recent years there has been an increased interest in trace metals in the atmosphere and the environmental effects of their deposition. This is to large extent because heavy metals can accumulate in the biosphere and may be toxic to living systems. On the basis of IIASA's TRACE model, the total (wet plus dry) deposition of As, Cd, Pb and Zn has been estimated for Eastern Europe. These are annual averages for rural areas, and relate to the situation in Europe in the mid-1980s. The maximum deposition value is 3.5 mg m^{-2} yr^{-1} for As, 1.5 mg m^{-2} yr^{-1} for Cd and 50 mg m^{-2} yr^{-1} for Zn. All these maxima occur in Southern Poland. The highest total deposition of Pb (15.0-20.0 mg m^{-2} yr^{-1}) has been computed for western Czechoslovakia and also for southern Poland. Deposition levels throughout most of Eastern Europe are at least one or two orders of magnitude greater than observed in remote parts of the world. The annual average concentration of metals in some rural areas are lower, but within a factor of two of drinking water guidelines. This is cause for concern because some short-term concentrations are almost assuredly much higher than the annual average. Because of long-range transport, there is a very significant transboundary exchange of heavy metals within Eastern Europe. As with acid-causing pollutants, the problem of heavy metals contamination in the region depends on the reduction of this transboundary pollution

An Efficient Positive Definite Method for the Numerical Solution of the Advection Equation

A numerical Positive Definite Pseudo-Spectral (PDPS) method for the solution of the advection equation is presented. The method consists of two parts. For each time step first a solution using a pseudospectral method is computed. Then the solution is corrected by a filtering procedure which eliminates negative values. The numerical test with the rotational velocity field and different initial conditions shows that the present method has the accuracy of the pseudospectral one without producing negative values. An additional advantage of the PDPS method is the elimination of spurious artificial shortwaves typical for the pseudospectral solution

Atmospheric deposition of nitrogen to the Baltic Sea in the period 1995–2006

The EMEP/MSC-W model has been used to compute atmospheric nitrogen deposition into the Baltic Sea basin for the period of 12 yr: 1995–2006. The level of annual total nitrogen deposition into the Baltic Sea basin has changed from 230 Gg N in 1995 to 199 Gg N in 2006, decreasing 13 %. This value corresponds well with the total nitrogen emission reduction (11 %) in the HELCOM Contracting Parties. However, inter-annual variability of nitrogen deposition to the Baltic Sea basin is relatively large, ranging from −13 % to +17 % of the averaged value. It is mainly caused by the changing meteorological conditions and especially precipitation in the considered period. The calculated monthly deposition pattern is similar for most of the years showing maxima in the autumn months October and November. The source allocation budget for atmospheric nitrogen deposition to the Baltic Sea basin was calculated for each year of the period 1997–2006. The main emission sources contributing to total nitrogen deposition are: Germany 18–22 %, Poland 11–13 % and Denmark 8–11 %. There is also a significant contribution from distant sources like the United Kingdom 6–9 %, as well as from the international ship traffic on the Baltic Sea 4–5 %

Atmospheric Models and Acidification

Three topics are discussed in this report: sensitivity/uncertainty analysis of long range transport models, the interface between atmospheric models of different scales, and linkage between atmospheric and ecological models. In separate analyses of long range transport models, it was found that uncertainty of annual S deposition was mostly affected by uncertainty of wind velocity, mixing height and wet deposition parameterization. Uncertain parameters collectively caused S deposition errors of around 10-25% (coefficient of variation) in the models examined. The effect of interannual meteorological variability on computed annual S deposition was relatively small. Different methods were presented for combining models of regional and interregional scale. It was found to be more important to include interregional information in regional-scale models for annual computations compared to episodic computations. A variety of linkage problems were noted between atmospheric and ecological models. The vertical distribution of pollutants and "forest fittering" of pollutant deposition were found to be important in ecological impact calculations but lacking in the output of most interregional atmospheric models