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Baumgart J.,Ravensburg-Weingarten University of Applied Sciences
Advanced Optical Technologies

Light guiding backlights are a good solution to attain ambient or display illuminations. Generally, they are attained using intended macroscopic defects (dots). Their size, shape and density are designed using ray tracing software. Smaller defects have the fascinating feature that they may not be perceived by the eye. Such a light guide will therefore look transparent and undisturbed. However, such microscopic or even nanoscaled defects are well beyond the limitations of geometrical optics and therefore need other approaches for their design. An interesting alternative to surface defects are particles inside the material or a well-defined surface roughness. In contrast to a defect structure, particle densities or surface roughness cannot be changed without difficulty. These may, however, be much more easily manufactured. In this paper, a simple analytical method for the design of such light guides will be presented. This method is compared to the results of commercial software and will be used to design a homogeneous illumination adopting constant particle density inside the material. © 2013 Thoss Media & De Gruyter. Source

Weber B.,University of Innsbruck | Mutschler B.,Ravensburg-Weingarten University of Applied Sciences | Reichert M.,University of Ulm
Science of Computer Programming

Business Process Management (BPM) technology has become an important instrument for supporting complex coordination scenarios and for improving business process performance. When considering its use, however, enterprises typically have to rely on vendor promises or qualitative reports. What is still missing and what is demanded by IT decision makers are quantitative evaluations based on empirical and experimental research. This paper picks up this demand and illustrates how experimental research can be applied to technologies enabling enterprises to coordinate their business processes and to associate them with related artifacts and resources. The conducted experiment compares the effort for implementing and maintaining a sample business process either based on standard workflow technology or on a case handling system. We motivate and describe the experimental design, discuss threats for the validity of our experimental results (as well as risk mitigations), and present the results of our experiment. In general, more experimental research is needed in order to obtain valid data on the various aspects and effects of BPM technology and BPM tools. © 2009 Elsevier B.V. All rights reserved. Source

Mutschler B.,Ravensburg-Weingarten University of Applied Sciences | Reichert M.,University of Ulm
Studies in Computational Intelligence

Providing effective IT support for business processes has become crucial for enterprises to stay competitive in their market. Business processes must be defined, configured, implemented, enacted, monitored and continuously adapted to changing situations. Process life cycle support and continuous process improvement have therefore become critical success factors in enterprise computing. In response to this need, a variety of process support paradigms, process specification standards, process management tools, and supporting methods have emerged. Summarized under the term Business Process Management (BPM), they have become a successcritical instrument for improving overall business performance. However, introducing BPM approaches in enterprises is associated with significant costs. Though existing economic-driven IT evaluation and software cost estimation approaches have received considerable attention during the last decades, it is difficult to apply them to BPM projects. In particular, they are unable to take into account the dynamic evolution of BPM projects caused by the numerous technological, organizational and project-specific factors influencing them. The latter, in turn, often lead to complex and unexpected cost effects in BPM projects making even rough cost estimations a challenge. What is needed is a comprehensive approach enabling BPM professionals to systematically investigate the costs of BPM projects. This chapter takes a look at both known and often unknown cost factors in BPM projects, shortly discusses existing IT evaluation and software cost estimation approaches with respect to their suitability for BPM projects, and finally introduces the Eco- POST framework. EcoPOST utilizes evaluation models to describe the interplay of technological, organizational, and project-specific BPM cost factors as well as simulation concepts to unfold the dynamic behavior and costs of BPM projects. © Springer-Verlag Berlin Heidelberg 2013. Source

Tokic M.,Ravensburg-Weingarten University of Applied Sciences | Tokic M.,University of Ulm
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

This paper presents "Value-Difference Based Exploration" (VDBE), a method for balancing the exploration/exploitation dilemma inherent to reinforcement learning. The proposed method adapts the exploration parameter of ε-greedy in dependence of the temporal-difference error observed from value-function backups, which is considered as a measure of the agent's uncertainty about the environment. VDBE is evaluated on a multi-armed bandit task, which allows for insight into the behavior of the method. Preliminary results indicate that VDBE seems to be more parameter robust than commonly used ad hoc approaches such as ε-greedy or softmax. © 2010 Springer-Verlag Berlin Heidelberg. Source

Kurniawan T.A.,Ravensburg-Weingarten University of Applied Sciences | Kurniawan T.A.,University of Eastern Finland | Sillanpaa M.E.T.,University of Eastern Finland | Sillanpaa M.,Finnish Environment Institute
Critical Reviews in Environmental Science and Technology

The authors present an overview with critical analysis of technical applicability of various nanoadsorbents such as carbon nanotubes, nano-zerovalent iron, and metal oxides-based and polymeric nanoparticles in treating contaminated water. To highlight their performance, selected information such as synthesis method, pH, dose required, pollutant's concentrations, reaction time, and treatment efficiency is presented based on the literature survey of 276 articles (1989-2010). Their advantages and drawbacks in applications are evaluated. Nanoadsorbents that stand out for outstanding performance are compared to bulk activated carbon. The implications of nanoadsorbents to public health and their way forward for facilitating environmental sustainability are also discussed. © 2012 Taylor & Francis Group, LLC. Source

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