Real-Time Solution of Bi-Level Optimal Control Problems

Bi-level optimal control problems are presented as an extension to classical optimal control problems. Hereby, additional constraints for the primary problem are considered, which depend on the optimal solution of a secondary optimal control problem. A demanding problem is the numerical complexity, since at any point in time the solution of the optimal control problem as well as a complete solution of the secondary problem have to be determined. Hence we deal with two dependent variables in time. The numerical solution of the bi-level problem is illustrated by an application of a container crane. Jerk and energy optimal trajectories with free final time are calculated under the terminal condition that the crane system comes to be at rest at a predefined location. In enlargement additional constraints are investigated to ensure that the crane system can be brought to a rest position by a safety stop at a free but admissible location in minimal time from any state of the trajectory. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

The Chemistry of Cyborgs—Interfacing Technical Devices with Organisms

The term “cyborg” refers to a cybernetic organism, which characterizes the chimera of a living organism and a machine. Owing to the widespread application of intracorporeal medical devices, cyborgs are no longer exclusively a subject of science fiction novels, but technically they already exist in our society. In this review, we briefly summarize the development of modern prosthetics and the evolution of brain–machine interfaces, and discuss the latest technical developments of implantable devices, in particular, biocompatible integrated electronics and microfluidics used for communication and control of living organisms. Recent examples of animal cyborgs and their relevance to fundamental and applied biomedical research and bioethics in this novel and exciting field at the crossroads of chemistry, biomedicine, and the engineering sciences are presented.     

B-CALM: An open-source GPU-based 3D-FDTD with multi-pole dispersion for plasmonics

Numerical calculations with finite-difference time-domain (FDTD) on metallic nanostructures in a broad optical spectrum require an accurate approximation of the permittivity of dispersive materials. In this paper, we present the algorithms behind B-CALM (Belgium-California Light Machine), an open-source 3D-FDTD solver operating on Graphical Processing Units with multi-pole dispersion models. Our modified architecture shows a reduction in computing times for multi-pole dispersion models. We benchmark B-CALM by computing the absorption efficiency of a metallic nanosphere on a broad spectral range with a six-poles Drude-Lorentz model and compare it with Mie theory.

     

Asynchronous sampling for ultrafast experiments with low momentum compaction at the ANKA ring

A high‐repetition‐rate pump–probe experiment is presented, based on the asynchronous sampling approach. The low‐α mode at the synchrotron ANKA can be used for a time resolution down to the picosecond limit for the time‐domain sampling of the coherent THz emission as well as for hard X‐ray pump–probe experiments, which probe structural dynamics in the condensed phase. It is shown that a synchronization of better than 1 ps is achieved, and examples of phonon dynamics of semiconductors are presented.     

Crystallographic report: Octameric sodium trimethylsilanolate hemihydrate hemi‐THF solvate, [$\hbox{NaOSiMe}_{3}{ \cdot} {1 \over 2} \hbox{H}_{2}\hbox{O}{\cdot} {1 \over 2}$THF]8

The title compound is composed of two Na₄O₄ heterocubanes which are connected via four µ‐OSiMe₃ groups. The oxygen atoms of the water molecules occupy two corners of an Na₄O₄ cube and additionally form hydrogen bonds to the µ‐OSiMe₃ groups with O·O distances in the range 2.649(4)–2.714(4) Å. Copyright © 2004 John Wiley & Sons, Ltd.