Fatigue analysis of miniaturized lead-free solder contacts based on a novel test concept

The paper presents the method of generating lifetime-prediction-laws on special prepared very stiff specimen. The combination of thin- and thick-film technology allows building up test samples on ceramic very similar to electronic packages including the measurement issues. Influences of pad surface metallurgy, microstructure of solder, ineutectic solder alloys and assembly process parameter are regarded now. The investigation objects provide monitoring of electrical and mechanical damage process of SnAgCu solder bump. Different thermo-mechanical loads will be applied in temperature ranges of 0 to +80 °C, −40 to +125 °C and −50 to +150 °C, where the temperature gradient and cycle frequency also vary. A Variation of four different chip sizes allows the determination of fatigue laws for each temperature profile, to be able to compare in between them. The results of these tests will give universal lifetime-prediction laws for SnAgCu base solder joints. Main goals are to find coefficients for lifetime prediction models such as Coffin–Manson- or Norris–Landzberg-relation, which are transferable in between different electronic packages.     

CD2/CD21 index: A new marker to evaluate udder health in dairy cows

Lymphocytes play a significant role in the immunological processes of the bovine mammary gland and were found to be the dominant cell population in the milk of healthy udder quarters. The objective of this study was to investigate the quantitative relationship between CD2⁺ T and CD21⁺ B lymphocytes using flow cytometry. In a first study, quarter foremilk samples from apparently healthy udder quarters [somatic cell counts (SCC) ≤100,000 cells/mL; n = 65] were analyzed and compared with diseased quarters (SCC >100,000 cells/mL; n = 15). Percentages of CD2⁺ T cells were significantly higher in milk samples with SCC ≤100,000 cells/mL than in those with SCC >100,000 cells/mL, whereas percentages of CD21⁺ B cells developed in the opposite direction. As a result of this opposing trend, a new variable, the CD2/CD21 index—representing the percentages of CD2⁺ cells per CD21⁺ cells—was defined. Although diseased quarters with SCC >100,000 cells/mL and the detection of major pathogens revealed generally CD2/CD21 indices <10, values >10 were observed in apparently healthy quarters. Hence, a CD2/CD21 index cutoff value of 10 may be suitable to aid differentiation between unsuspicious and microbiologically suspicious or diseased udder quarters. To test whether CD2/CD21 indices <10 were primarily related to pathogens, quarters with SCC ≤100,000 cells/mL and >100,000 cells/mL with different bacteriological status (culture negative, or minor or major pathogens) were selectively examined in a second biphasic study. In the first trial, 63 udder quarters were analyzed and 55 of these quarters were able to be sampled again in the second trial carried out 14 d later. In both trials, results of the first study were confirmed. Indeed, CD2/CD21 indices <10 were also found in quarters showing SCC ≤100,000 cells/mL and containing minor or major pathogens at the time of the current or previous bacteriological analysis. The results of our examinations indicated a clear relationship between the CD2/CD21 index and the bacteriological status of the mammary gland. In combination with SCC, it offers a new marker for quick differentiation of unsuspicious and microbiologically suspicious or diseased udder quarters.     

Fast 3D inverse simulation of hot forging processes via Medial Axis Transformation: an approach for preform estimation in hot die forging

In hot die forging processes, the selection of an ideal preform is of great importance with respect to cavity filling and mechanical load. The common procedure in order to define an adequate preform is the usage of Finite-Element-Analysis (FEA), usually as an iterative process in which various preforms are tested with regard to their suitability. An approach that aims at reducing the number of trials by proposing a first estimation of a suitable preform is presented in this paper. It is conjectured that the material flow paths and resistance can be described by the cavity shape using the Medial Axis Transformation. Based on this, a local inverse material flow for time discrete steps is calculated. The result is a first estimation of an adequate preform shape within a few minutes as an input for further FEA. FE-based parametric design optimization procedure is then presented and compared to the inverse approach, which is identified as a useful complement for the forward simulation technique.     

The influence of diffuse pollution on groundwater content patterns for the groundwater bodies of Germany.

Commissioned by Germany's Working Group of the Federal States on Water Problems (LAWA) the authors developed a procedure to define natural groundwater conditions from groundwater monitoring data. The distribution pattern of a specific groundwater parameter observed by a number of groundwater monitoring stations within a petrographically comparable groundwater typology is reproduced by two statistical distribution functions, representing the "natural" and "influenced" component. The range of natural groundwater concentrations is characterized by confidence intervals of the distribution function of the natural component. The applicability of the approach was established for 17 hydrochemical different groundwater typologies occurring throughout Germany. Based on groundwater monitoring data from ca. 26,000 groundwater-monitoring stations, 40 different hydrochemical parameters were evaluated for each groundwater typology. For all investigated parameters the range of natural groundwater concentrations has been identified. According to the requirements of the EC Water Framework Directive (article 17) (WFD) this study is a basis for the German position to propose criteria for assessing a reference state for a "good groundwater chemical status".     

Vaporization study of sodium sulphate — potassium sulphate binary system by Knudsen effusion mass spectrometry

The vaporization of samples of different chemical and phase compositions in the Na₂SO₄-K₂SO₄ system was investigated over the temperature range 1100 K–1400 K by the use of Knudsen effusion mass spectrometry. The gaseous species Na(g), Na₂SO₄(g), K(g), K₂SO₄(g), SO₂(g), O₂(g) and NaKSO₄(g) were identified in the vapour over the samples investigated. The thermodynamic activities of sulphates in the examined system at 1350 K were obtained, which allowed calculating the chemical composition of the vapours present in the high temperature zone of cement kilns.     

Analysis of results from the operation of a pilot plasma gasification/vitrification unit for optimizing its performance

Plasma gasification/vitrification is an innovative and environmentally friendly method of waste treatment. A demonstration plasma gasification/vitrification unit was developed and installed in Viotia region in order to examine the efficiency of this innovative technology in dealing with hazardous waste. The preliminary results from the trial runs of the plasma unit, as well as the study of the influence of certain parameters in the system performance are presented and analyzed in this paper, contributing to the improvement of the operation performance. Finally, data on the final air emissions and the vitrified ash toxicity characteristic leaching procedure (TCLP) results are provided in order to assess the environmental performance of the system. The produced slag was found to be characterized by extremely low leaching properties and can be utilized as construction material, while the values of the polluting parameters of the air emissions were satisfactory.     

Sustainable energy development in Austria until 2020: Insights from applying the integrated model "e3.at"

This paper reports on the Austrian research project "Renewable energy in Austria: Modeling possible development trends until 2020". The project investigated possible economic and ecological effects of a substantially increased use of renewable energy sources in Austria. Together with stakeholders and experts, three different scenarios were defined, specifying possible development trends for renewable energy in Austria. The scenarios were simulated for the period 2006-2020, using the integrated environment-energy-economy model "e3.at". The modeling results indicate that increasing the share of renewable energy sources in total energy use is an important but insufficient step towards achieving a sustainable energy system in Austria. A substantial increase in energy efficiency and a reduction of residential energy consumption also form important cornerstones of a sustainable energy policy.     

Somatic cell counts and bacteriological status in quarter foremilk samples of cows in Hesse, Germany--a longitudinal study

Somatic cell counts (SCC) are generally used as an indicator of udder health. Currently in Germany, 100,000 cells/mL is the threshold differentiating infected and noninfected mammary glands. The aim of our study was the detailed analysis of udder health in a representative part of the dairy cow population in Hesse, Germany. Between 2000 and 2008, 615,187 quarter foremilk samples were analyzed. In addition to evaluation of distribution of SCC and prevalence of mastitis pathogens, pathogen prevalence was also calculated depending on SCC. The data indicated that 38% of all samples had SCC >100,000 cells/mL and 62% showed SCC ≤100,000 cells/mL; 31% of all samples revealed SCC ≤25,000 cells/mL. Coagulase-negative staphylococci were the dominant pathogens in the Hessian quarter foremilk samples (17.17% of all samples) followed by Corynebacterium spp. (13.56%), Streptococcus uberis (8.7%), and Staphylococcus aureus (5.01%). Mastitis pathogens were detected in 83% of all samples with SCC >100,000 cells/mL. However, the prevalence of mastitis pathogens in the SCC range from 1,000 to ≤100,000 cells/mL was 8.5% (5.51% minor pathogens, 2.01% major pathogens, and 0.98% other pathogens). For farms producing high quality milk, exceptional hygiene management is compulsory. One of the farms randomly selected showed clearly different results from the Hessian survey. Fifteen percent more samples lay in the SCC range ≤100,000 cells/mL with a lower prevalence of mastitis pathogens of 1.91% (1.03% minor pathogens, 0.83% major pathogens, and 0.05% other pathogens). Based on these results, inflammatory processes can obviously be detected in mammary glands of udder quarters healthy according to the current definitions. However, we argue that such inflammation can be detected by examination of the relationship of immune cells in milk.     

Impact of sourdough fermented with Lactobacillus plantarum FST 1.7 on baking and sensory properties of gluten-free breads

Sourdoughs were produced from buckwheat, oat, quinoa, sorghum, teff and wheat flour using the heterofermentative lactic acid bacteria Lactobacillus plantarum FST 1.7 and added to a basic bread formulation of flour from the same grain type (20 % addition level). Dough rheology, textural (crumb hardness, specific volume) and structural bread characteristics (crumb porosity, cell volume, brightness) of sourdough-containing breads were compared to non-sourdough-containing breads (control). Changes in protein profiles as analysed with capillary electrophoresis were observed in all sourdoughs. Furthermore, sourdough addition led to decreased dough strength resulting in softer dough. No influences on specific volume and hardness on day of baking were found for gluten-free sourdough breads. The staling rate was reduced in buckwheat (from 8 ± 2 to 6 ± 2 N/day) and teff sourdough bread (13 ± 1 to 10 ± 4 N/day), however, not significantly in comparison with the control breads. On the contrary, in wheat sourdough bread, the staling rate was significantly reduced (2 ± 1 N/day) in comparison with control bread (5 ± 1 N/day). Sourdough addition increased the cell volume significantly in sorghum (+61 %), teff (+92 %) and wheat sourdough breads (+78 %). Therefore, crumb porosity was significantly increased in all gluten-free and wheat sourdough breads. Shelf life for sourdough breads was one (teff and oat), two (buckwheat, quinoa and sorghum) and 3 days (wheat) and was not prolonged by sourdough addition. The inferior aroma of breads prepared from the gluten-free flours was also not improved by sourdough addition.