Benchmarking semiconductor manufacturing performance using apairwise-comparison method

Benchmarking performance against competitors is an increasingly popular activity within the semiconductor industry. Owing to the high variability in manufacturing metrics, a simple monthly metric score is usually insufficient to accurately benchmark performance. However, in the rapidly changing semiconductor world, data which are one to two years old may be irrelevant to the current situation. We propose a simple ranking method based on a method of paired-comparisons for unbalanced data which gives a good ranking and is also reliable under fluctuations in the data. Using semiconductor manufacturing performance data from the Competitive Semiconductor Manufacturing Study at the University of California at Berkeley, we give an example of this method and compare its reliability and accuracy against other techniques through simulations     

Comparison of RRR-alpha- and all-rac-alpha-tocopherol uptake by permanent rat skeletal muscle myoblasts (L6 cells): effects of exogenous lipoprotein lipase

The purpose of the present investigation was to test whether permanent skeletal muscle cells (rat L6 cells) could serve as an in vitro model for alpha-tocopherol (alphaTocH) biodiscrimination studies. L6 cells were incubated in the presence of high density lipoprotein (HDL), low density lipoprotein (LDL), and very low density lipoprotein (VLDL) labeled in the lipid moiety with either all-rac- or RRR-[14C]alphaTocH. These incubations were performed either in the absence or in the presence of exogenously added bovine lipoprotein lipase (LPL) since skeletal muscle is one of the major expression sites of LPL in vivo. Time-dependent uptake studies (up to 24 h) in the absence of LPL have shown that equipotent doses of all-rac- and RRR-[14C]alphaTocH (1.36:1) led to almost identical accumulation of the tracer, independent of the lipoprotein class used as alphaTocH carrier. With regard to alphaTocH donor capacity, it appeared that HDL is the most potent alphaTocH donor, followed by LDL and VLDL. In the presence of LPL, all-rac- and RRR-[14C]alphaTocH uptake was significantly enhanced (between two- and tenfold). Biodiscrimination studies using chiral high-performance liquid chromatographic analysis with radiometric detection of the corresponding methyl ether derivatives on a Chiralcel OD column have demonstrated that the 2S-and 2R-isomers of alphaTocH were taken up in a 1:1 ratio by L6 cells independent of the absence or presence of LPL. In addition, we have not observed biodiscrimination between the four 2R-isomers, i.e., there was no preferential accumulation of the RRR-isomer. These data suggest that L6 cells do not discriminate between different alphaTocH isomers and that the addition of endogenous LPL significantly enhances the uptake of RRR- and all-rac-alphaTocH.     

Acquisition, Synthesis, and Rendering of Bidirectional Texture Functions

One of the main challenges in computer graphics is still the realistic rendering of complex materials such as fabric or skin. The difficulty arises from the complex meso structure and reflectance behavior defining the unique look‐and‐feel of a material. A wide class of such realistic materials can be described as 2D‐texture under varying light‐ and view direction, namely, the Bidirectional Texture Function (BTF). Since an easy and general method for modeling BTFs is not available, current research concentrates on image‐based methods, which rely on measured BTFs (acquired real‐world data) in combination with appropriate synthesis methods. Recent results have shown that this approach greatly improves the visual quality of rendered surfaces and therefore the quality of applications such as virtual prototyping. This state‐of‐the‐art report (STAR) will present the techniques for the main tasks involved in producing photo‐realistic renderings using measured BTFs in details.     

Prospects of solar thermal hydrogen production processes

This article provides a critical discussion of prospects of solar thermal hydrogen production in terms of technological and economic potentials and their possible role for a future hydrogen supply. The study focuses on solar driven steam methane reforming, thermochemical cycles, high temperature water electrolysis and solar methane cracking. Development status and technological challenges of the processes and objectives of ongoing research are described. Estimated hydrogen production costs are shown in comparison to other options. A summary of current discussions and today's scenarios of future use of hydrogen as an energy carrier and a brief overview on the development status of end-use technologies characterise uncertainties whether hydrogen could emerge as important energy carrier until 2050. Another focus is on industrial hydrogen demand in areas with high direct solar radiation which may be the main driver for the further development of solar thermal hydrogen production processes in the coming decades.     

Non-metallic inclusions and their relation to the J-integral, Ji, phys, at physical crack initiation for different steels and weld metals

For two types of steel, the heat-resistant 12% Cr–steel X 20 CrMoV 12 1 and the fine-grained pressure vessel steel 20 MnMoNi 5 5 (A 508 cl.3), a wide range of toughness values in the upper shelf was realized by different sulfur contents and the inclusion of similar weld metals. Additionally, the pressure vessel steel 22 NiMoCr 3 7 (A 508 cl.2) was also investigated. Tensile, fracture mechanics and Charpy V-notch impact tests, as well as detailed microstructural investigations with respect to the size distribution and density of non-metallic inclusions and precipitates, were carried out. In order to ensure ductile behaviour, a test temperature of 150 °C was chosen. The relevance of two quantitative relations available for the calculation of the J-integral, Ji, phys, at physical crack initiation using tensile test data and microstructural parameters, were examined by comparison with the corresponding experimental Ji, phys-values. Only one quantitative relation was able to give good agreement between calculated and experimental Ji, phys-values. This holds not only for the base materials but also for the weld metals. The importance of the size and density of the non-metallic inclusions became quantitatively obvious with the consequence that their size times density is a decisive parameter for toughness. Observations of void initiation, growth and coalescence illustrate the fracture process. © 1998 Chapman & Hall     

Semiautomatic method for histomorphometry

A semiautomatic measurement system for histomorphometry is presented. The system is based on a steppermotor-driven scanning stage which the operator controls via a digitizer. Movement in the scanning stage is carried out with respect to stationary cross-wires in the ocular of the microscopy. The system is connected to a PC-AT computer which utilizes the x- and y-coordinates of these movements for the calculation of the morphometric measurements. In addition, the system is supplemented by software for storage and analysis of measurement data.     

Thermodynamic analysis of two‐step solar water splitting with mixed iron oxides

A two‐step thermochemical cycle for solar production of hydrogen from water has been developed and investigated. It is based on metal oxide redox pair systems, which can split water molecules by abstracting oxygen atoms and reversibly incorporating them into their lattice. After successful experimental demonstration of several cycles of alternating hydrogen and oxygen production, the present work describes a thermodynamic study aiming at the improvement of process conditions and at the evaluation of the theoretical potential of the process. In order to evaluate the maximum hydrogen production potential of a coating material, theoretical considerations based on thermodynamic laws and properties are useful and faster than actual tests. Through thermodynamic calculations it is possible to predict the theoretical maximum output of H₂ from a specific redox‐material under certain conditions. Calculations were focussed on the two mixed iron oxides nickel–iron‐oxide and zinc–iron‐oxide. In the simulation the amount of oxygen in the redox‐material is calculated before and after the water‐splitting step on the basis of laws of thermodynamics and available material properties for the chosen mixed iron oxides. For the simulation the commercial Software FactSage and available databases for the required material properties were used. The analysis showed that a maximum hydrogen yield is achieved if the reduction temperature is raised to the limits of the operation range, if the temperature for the water splitting is lowered below 800°C and if the partial pressure of oxygen during reduction is decreased to the lower limits of the operational range. The predicted effects of reduction temperature and partial pressure of oxygen could be confirmed in experimental studies. The increased hydrogen yield at lower splitting temperatures of about 800°C could not be confirmed in experimental results, where a higher splitting temperature led to a higher hydrogen yield. As a consequence it can be stated that kinetics must play an important role especially in the splitting step. Copyright © 2009 John Wiley & Sons, Ltd.     

Experimental study on sulfur trioxide decomposition in a volumetric solar receiver–reactor

Process conditions for the direct solar decomposition of sulfur trioxide have been investigated and optimized by using a receiver–reactor in a solar furnace. This decomposition reaction is a key step to couple concentrated solar radiation or solar high‐temperature heat into promising sulfur‐based thermochemical cycles for solar production of hydrogen from water. After proof‐of‐principle a modified design of the reactor was applied. A separated chamber for the evaporation of the sulfuric acid, which is the precursor of sulfur trioxide in the mentioned thermochemical cycles, a higher mass flow of reactants, an independent control and optimization of the decomposition reactor were possible. Higher mass flows of the reactants improve the reactor efficiency because energy losses are almost independent of the mass flow due to the predominant contribution of re‐radiation losses. The influence of absorber temperature, mass flow, reactant initial concentration, acid concentration, and residence time on sulfur trioxide conversion and reactor efficiency has been investigated systematically. The experimental investigation was accompanied by energy balancing of the reactor for typical operational points. The absorber temperature turned out to be the most important parameter with respect to both conversion and efficiency. When the reactor was applied for solar sulfur trioxide decomposition only, reactor efficiencies of up to 40% were achieved at average absorber temperature well below 1000°C. High conversions almost up to the maximum achievable conversion determined by thermodynamic equilibrium were achieved. As the re‐radiation of the absorber is the main contribution to energy losses of the reactor, a cavity design is predicted to be the preferable way to further raise the efficiency. Copyright © 2009 John Wiley & Sons, Ltd.