Volatilization and Transport Mechanisms During Cr Oxidation at 300 °C Studied In Situ by ToF-SIMS

The oxidation of chromium at 300 °C was investigated in situ by ToF-SIMS for three different oxygen pressures (\(P_{{{\text{O}}_{2} }} = 2.0 \times 10^{ - 7}\), 6.0 × 10^?7 and 2.0 × 10^?6 mbar). Sequential exposure to the ¹⁸O isotopic tracer was performed to reveal the governing transport mechanism in the oxide film. The evolution of the oxide thickness was monitored. Volatilization of Cr₂O₃ was evidenced. A model was used to describe the kinetics resulting from the measurements. Both the parabolic and volatilization constants showed a dependence on oxygen partial pressure like \(P_{{{\text{O}}_{2} }}^{ - 1/n}\), with n = 1.9 ± 0.1, indicating a defect structure mainly consisting of oxygen vacancies. The re-oxidation in ¹⁸O₂ shows a growth of the oxide layer at the metal/oxide interface, demonstrating an oxidation process governed by anionic transport via oxygen vacancies. The diffusion coefficient of oxygen in the oxide was determined by fitting the ToF-SIMS depth profiles. It is 2.0 × 10^?18 cm² s^?1.     

An integrated system solution for supply chain optimization in the chemical process industry

This paper considers a complex scheduling problem in the chemical process industry involving batch production. The application described comprises a network of production plants with interdependent production schedules, multi-stage production at multi-purpose facilities, and chain production. The paper addresses three distinct aspects: (i) a scheduling solution obtained from a genetic algorithm based optimizer, (ii) a mechanism for collaborative planning among the involved plants, and (iii) a tool for manual updates and schedule changes. The tailor made optimization algorithm simultaneously considers alternative production paths and facility selection as well as product and resource specific parameters such as batch sizes, and setup and cleanup times. The collaborative planning concept allows all the plants to work simultaneously as partners in a supply chain resulting in higher transparency, greater flexibility, and reduced response time as a whole. The user interface supports monitoring production schedules graphically and provides custom-built utilities for manual changes to the production schedule, investigation of various what-if scenarios, and marketing queries. RID="*" ID="*" The authors would like to thank Hans-Otto Günther and Roland Heilmann for helpful comments on draft versions of this paper.     

Views and Patterns in E-Commerce Application Design

Separation of concerns is a well-established principle in software engineering that supports reuse by hiding complexity through abstraction mechanisms. The Abstract Design Views model was created with reuse in mind and allows the designer to apply separation of concerns in a software system from the design to the implementation. In this model, viewed objects represent the basic concern, i.e., the algorithms that provide the essential functionality relevant to an application domain, and viewer objects represent the special concerns related to other software issues, such as user interface presentation, synchronization, and timing. In this paper we use a reuse taxonomy to analyze and validate this model. Using this analysis and the properties of the relationship between viewer and viewed objects, called views, we also indicate how to map the views-based designs into implementations based on design patterns that satisfy the views properties. Finally, we show how to apply the principles of our approach, using views and the design patterns, to design e-commerce applications.     

Robust inference of trees

This paper is concerned with the reliable inference of optimal tree-approximations to the dependency structure of an unknown distribution generating data. The traditional approach to the problem measures the dependency strength between random variables by the index called mutual information. In this paper reliability is achieved by Walley's imprecise Dirichlet model, which generalizes Bayesian learning with Dirichlet priors. Adopting the imprecise Dirichlet model results in posterior interval expectation for mutual information, and in a set of plausible trees consistent with the data. Reliable inference about the actual tree is achieved by focusing on the substructure common to all the plausible trees. We develop an exact algorithm that infers the substructure in time O(m ⁴), m being the number of random variables. The new algorithm is applied to a set of data sampled from a known distribution. The method is shown to reliably infer edges of the actual tree even when the data are very scarce, unlike the traditional approach. Finally, we provide lower and upper credibility limits for mutual information under the imprecise Dirichlet model. These enable the previous developments to be extended to a full inferential method for trees.     

Location Models for Augmented Environments

In this paper we describe two projects on contextualized computer systems and audio augmented environments we are currently working on at the Fraunhofer Institutes FIT and IMK. In this paper we will only focus on the world models and the augmentation layer. Both projects are based on completely different technologies, and use different representation methods and interaction facilities. While in hippie users are moving with small laptop computers or wearable computers with a small visual display, in LISTEN users will have only a wireless headphone displaying spatially rendered sound-scenes. Correspondence to: J. Goβmann, Fraunhofer-IMK, Schloss Birlinghoven, D-53754 St Augustin, Germany.     

The Golden Section in Architectural Theory

The never-ending—but always young—discussion about the Golden Section in architecture never lacks a hint at Luca Pacioli and architectural theory. But what it always lacks is a thorough study of the Golden Section in architectural theory. This paper aims to present this analysis. Marcus Frings traces the Golden Section from the mathematical and rather theoretical character of Pacioli’s concept, the the treatises of Alberti, Serlio, and Palladio, to Adolf Zeising in the nineteenth century. and to theorist Matila Ghyka and the practitioners Ernst Neufert and Le Corbusier in the twentieth. In the latter’s writings and designs the Golden Section seems to play the role of a scholarly element which shows the master’s theoretical erudition, leading to contemporary architects such as Ricardo Bofill.