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

Thermal Tolerance of Alligator Gar (Atractosteus spatula)

Alligator gar belong to an ancient lineage that dates back over 215 million years. Historically, alligator gar populations occurred in the Mississippi River basin from Illinois (USA) to Mexico. Alligator gar populations have been reduced or extirpated throughout much of their range, and introductory programs have been implemented by some state and federal agencies attempting to reestablish historical populations. Efforts have been aided by studies investigating many ecological and life-history aspects of this species. However, thermal minima has yet to be evaluated for alligator gar. The goal of this thesis is to provide quantified estimates of alligator gar minima temperatures and to forecast potential range distribution based on current and predicted future climate scenarios. Newly hatched alligator gar were collected from a hatchery. The gar were acclimated to three different aquarium temperatures (21°C, 24.5°C, and 28°C) and then the water temperature was slowly decreased until the gar lost equilibrium. Variables (temperature[°C], total length [mm], and weight [g]) were tested for correlation and logistic regression models were used to determine the relationship between loss of equilibrium temperature and length or weight. Akaike’s information criterion scores were used to evaluate the best model. Additionally, alligator gar occurrence data was obtained from published papers, historical photos, field observations, and by downloading existence records from the Global Biodiversity Information Facility. These occurrences were combined with bioclimatic variables, terrestrial, aquatic and elevation data and then run in Maxent to estimate a current range and to forecast potential future ranges under different predicted climate scenarios. All variables were tested for correlation and Akaike’s information criterion scores in addition to receiver operating characteristics were used to evaluate models. Mean critical thermal minima temperatures obtained for each acclimation were 11.57°C, SD = 1.39 (21°C), 12.83°C, SD = 1.47 (24.5°C), and 14.16°C, SD = 1.60 (28°C). Alligator gar suitable habitat is expected to increase and shift to the north under all climate scenarios. The furthest shift north occurs under the most extreme warming scenario. This study provides the first quantified estimates of juvenile alligator gar thermal minima temperatures and fills a gap in alligator gar life history. The results from this study can be used in future studies aimed at conservation and management of alligator gar. Additionally, findings from this study can aid in determining the future northern extent of alligator gar distribution. Future research should investigate critical thermal minima of alligator gar larger than 519mm (the largest individual used in this study). Also, the survival of alligator gar that have been introduced at the northern edge of current projected suitable habitats should be followed to verify recruitment

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