The role of reversible temper embrittlement in TM-rolling of HSLA-steels

In TM-rolling of strip and plate the mill parameters can be adjusted such that reversible temper embrittlement (RTE) happens. This leads, together with the TM-typical grain elongation, to a special fracture appearance which consists of sub-fracture (split, separation) formation starting from the main fracture plane. The lower toughness in the thickness direction is connected with a sloping shelf of the otherwise sigmoidal energy temperature curve of impact bending tests with ISO-V(CVN) specimens. It is shown how RTE can be avoided, namely by low phosphorus contents of the material and/or by low coiling temperatures at strip rolling. Accelerated cooling of plates can avoid RTE, but care must be taken not to produce plates with lower toughness.     

Development of new concepts and software tools for the optimization of manual assembly systems

Due to growing numbers of differing products and variants, assembly systems with optimized manual workstations have become an efficient alternative to highly automated but less flexible production systems. Especially in the final stage of the product assembly, the flexibility of human employees enables them to meet the requirements for assembling various products and changing volumes. In order to create highly efficient production systems based on human work, it is necessary to develop innovative concepts for the design and organization of manual assembly structures. Another major issue is the development of software tools allowing the facility planner to simulate and optimize the complete design of the assembly structure such as the material flow or manual workstations, e.g. with respect to ergonomics, before construction. These requirements have led to a comprehensive research framework for manual assembly systems.     

Development of Specific Technologies and Assembly Systems for the New Challenge of Electro-Optical Devices

Today's information and communication systems are especially characterized by their capability and reliability of high data rate transmission. An integration of optical wave guides into printed circuit boards allows a hybrid electronics packaging in order to increase the data transmission rate. The success of this technology depends in particular on the availability of efficient production solutions. For this reason, the development of automated assembly systems for electro-optical components has become a main research field at the Institute for Manufacturing Automation and Production Systems. This paper describes the challenges of the placement systems and presents a continuous process chain for the automated assembly of electro-optical components.     

Tunable Volatility of Ge2Sb2Te5 in Integrated Photonics

The operation of a single class of optical materials in both a volatile and nonvolatile manner is becoming increasingly important in many applications. This is particularly true in the newly emerging field of photonic neuromorphic computing, where it is desirable to have both volatile (short‐term transient) and nonvolatile (long‐term static) memory operation, for instance, to mimic the behavior of biological neurons and synapses. The search for such materials thus far have focused on phase change materials where typically two different types are required for the two different operational regimes. In this paper, a tunable volatile/nonvolatile response is demonstrated in a photonic phase‐change memory cell based on the commonly employed nonvolatile material Ge₂Sb₂Te₅ (GST). A time‐dependent, multiphysics simulation framework is developed to corroborate the experimental results, allowing us to spatially resolve the recrystallization dynamics within the memory cell. It is then demonstrated that this unique approach to photonic memory enables both data storage with tunable volatility and detection of coincident events between two pulse trains on an integrated chip. Finally, improved efficiency and all‐optical routing with controlled volatility are demonstrated in a ring resonator. These crucial results show that volatility is intrinsically tunable in normally nonvolatile GST which can be used in both regimes interchangeably.     

Bemessung von Stahlbauten für Anprall‐ und Explosionslasten

Die zunehmende Gefahr von Anschlägen und Industrieunfällen haben zu neuen Anforderungen an die Auslegung und Bemessung von Bauwerken geführt. Diesen neuen Anforderungen wird derzeit in Normen jedoch nur unzureichend Rechnung getragen. Insbesondere für Bauwerke in Stahl‐ und Verbundbauweise führen die gegenwärtig üblichen Auslegungskonzepte nicht zu wirtschaftlichen Bemessungen. Das bauforumstahl hat daher in Zusammenarbeit mit dem Institut für Stahlbau der RWTH Aachen und HOCHTIEF Construction AG einen Bemessungsleitfaden für Anprall‐ und Explosionslasten erarbeitet, mit dem die Möglichkeiten des Werkstoffes Stahl wesentlich effizienter ausgenutzt werden können. In diesem Beitrag werden die wesentlichen Elemente dieses Leitfadens vorgestellt, der sowohl eine Bewertung von Entwurfsstrategien für robuste Bauwerke enthält, als auch ein Bemessungskonzept zur Auslegung von Stahlbauten gegen spezifische kurzzeit‐dynamische Einwirkungen bereitstellt. Design of steel structures against impact and blast loads. The increasing threat of terroristic attacks as well as industrial hazards have led to new demands for the conception and design of buildings. Current standards, however, do not provide sufficient guidance to cope with these new requirements. Particularly for steel and composite structures there is a lack of appropriate and therefore economic design concepts. Hence, bauforumstahl in cooperation with the Institute for Steel Structures at RWTH Aachen University and HOCHTIEF Construction AG has published a new design guide to exploit the capabilities of steel more efficiently. This paper presents the main aspects of this design guide. It includes the assessment of strategies for robust structures and a concept to design steel structures against specific high dynamic loads.     

RLadyBug—An R package for stochastic epidemic models

RLadyBug is an S4 package for the simulation, visualization and estimation of stochastic epidemic models in R. Maximum likelihood and Bayesian inference can be performed to estimate the parameters in a susceptible-exposed-infectious-recovered (SEIR) model, which is a stochastic model for describing a single outbreak of an infectious disease. The package is thus one step towards statistical software supporting parameter estimation, calculation of confidence intervals and hypothesis testing for transmission models.     

Application of UV depth lithography in micro system technology

This letter reports on new types of photo resists allowing UV-light exposure of thick layers. Optimized processes Cthat for the positive resist AZ 9260 and the negative resist Epon SU-8 have been developed enabling the fabrication of high aspect ratio metallic and polymer micro components. The high potential of this technology will be demonstrated on the basis of two examples, a variable reluctance micro motor with compensated attractive force and an optical microphone developed for application in electro-magnetic interference environments.     

Scaling analysis of conservative cascades, with applications tonetwork traffic

Previous studies have demonstrated that measured wide-area network traffic such as Internet traffic exhibits locally complex irregularities, consistent with multifractal behavior. It has also been shown that the observed multifractal structure becomes most apparent when analyzing measured network traffic at a particular layer in the well-defined protocol hierarchy that characterizes modern data networks, namely the transport or transmission control protocol (TCP) layer. To investigate this new scaling phenomenon associated with the dynamics of measured network traffic over small time scales, we consider a class of multiplicative processes, the so-called conservative cascades, that serves as a cascade paradigm for and is motivated by the networking application. We present a wavelet-based time/scale analysis of these cascades to determine rigorously their global and local-scaling behavior. In particular, we prove that for the class of multifractals generated by these conservative cascades the multifractal formalism applies and is valid, and we illustrate some of the wavelet-based techniques for inferring multifractal scaling behavior by applying them to a set of wide-area traffic traces     

Multi‐view reconstruction of dynamic real‐world objects and their integration in augmented and virtual reality applications

We present a flexible system for high‐quality three‐dimensional reconstruction of dynamic real‐world objects based on a modular multi‐camera capture setup. The proposed algorithmic pipeline aims at the acquisition and digitization of natural and realistic representations of real people that can be easily integrated into augmented and virtual reality applications. In this context, we discuss the reduction of mesh complexity as one of the key challenges for visualizing reconstructed three‐dimensional content with augmented and virtual reality glasses and demonstrate different fields of application.