TY - JOUR A1 - Abel, Markus A1 - Bergweiler, Steffen A1 - Gerhard, Reimund T1 - Synchronization of organ pipes : experimental observations and modeling N2 - We report measurements on the synchronization properties of organ pipes. First, we investigate influence of an external acoustical signal from a loudspeaker on the sound of an organ pipe. Second, the mutual influence of two pipes with different pitch is analyzed. In analogy to the externally driven, or mutually coupled self-sustained oscillators, one observes a frequency locking, which can be explained by synchronization theory. Further, we measure the dependence of the frequency of the signals emitted by two mutually detuned pipes with varying distance between the pipes. The spectrum shows a broad '' hump '' structure, not found for coupled oscillators. This indicates a complex coupling of the two organ pipes leading to nonlinear beat phenomena. Y1 - 2006 UR - http://scitation.aip.org/jasa/ U6 - https://doi.org/10.1121/1.217044 SN - 0001-4966 ER - TY - JOUR A1 - Abel, Markus A1 - Stojkovic, Dragan A1 - Breuer, Michael T1 - Nonlinear stochastic estimation of wall models for LES N2 - A key technology for large eddy simulation (LES) of complex flows is an appropriate wall modeling strategy. In this paper we apply for the first time a fully nonparametric procedure for the estimation of generalized additive models (GAM) by conditional statistics. As a database, we use DNS and wall-resolved LES data of plane channel flow for Reynolds numbers, Re = 2800, 4000 (DNS) and 10,935, 22,776 (LES). The statistical method applied is a quantitative tool for the identification of important model terms, allowing for an identification of some of the near-wall physics. The results are given as nonparametric functions which cannot be attained by other methods. We investigated a generalized model which includes Schumann's and Piomelli et al.'s model. A strong influence of the pressure gradient in the viscous sublayer is found; for larger wall distances the spanwise pressure gradient even dominates the tau(w,zy). component. The first a posteriori LES results are given. Y1 - 2006 UR - http://www.sciencedirect.com/science/journal/0142727X U6 - https://doi.org/10.1016/j.heatfluidflow.2005.10.011 SN - 0142-727X ER - TY - JOUR A1 - Akpo, Claudia A1 - Weber, Edwin A1 - Reiche, Jürgen T1 - Synthesis, Langmuir and Langmuir-Blodgett film behaviour of new dendritic amphiphiles JF - New journal of chemistry N2 - New amphiphilic compounds 1-9 that feature a construction with dendronized hydrophilic and hydrophobic segment groups connected to a specific aromatic or aliphatic spacer unit have been synthesized, following a modular building block strategy. The hydrophilic dendrons are typically branched elements with peripheral carboxylic groups, unlike the hydrophobic dendrons that contain peripheral alkyl chains as part of respective amide functions. The hydrophilic dendrons are in different generations of branching, while the hydrophobic dendrons are all in the first generation of branching (three terminal branching), but differ in the length of the alkyl chains, thus giving rise to designed structure and amphiphilic properties in the new compounds. The resulting surfactants are capable of forming well-defined Langmuir films of remarkable stability when spread from a solution onto an aqueous subphase. Nevertheless, specific packing behaviour and orientation of the amphiphilic molecules were found, depending on the molecular structure, as determined using analysis of the surface pressure-area (pi-A) isotherms. Langmuir-Blodgett transfer of the first monolayer from a pure water subphase to a clean silicon wafer proved possible for the amphiphiles of peripheral alkyl chain length C-12, while the amphiphiles with the longer alkyl chains failed, possibly due to the more rigid monolayers they form, impeding the transfer. Y1 - 2006 U6 - https://doi.org/10.1039/b609645j SN - 1144-0546 SN - 1369-9261 VL - 30 SP - 1820 EP - 1833 PB - RSC CY - Cambridge ER - TY - JOUR A1 - Albers, Nicole A1 - Spahn, Frank T1 - The influence of particle adhesion on the stability of agglomerates in Saturn's rings N2 - In planetary rings, binary collisions and mutual gravity are the predominant particle interactions. Based on a viscoelastic contact model we implement the concept of static adhesion. We discuss the collision dynamics and obtain a threshold velocity for restitution or agglomeration to occur. The latter takes place within a range of a few cm s(-1) for icy grains at low temperatures. The stability of such two-body agglomerates bound by adhesion and gravity in a tidal environment is discussed and applied to the saturnian system. A maximal agglomerate size for a given orbit location is obtained. In this way we are able to resolve the borderline of the zone where agglomerates can exist as a function of the agglomerate size and thus gain an alternative to the classical Roche limit. An increasing ring grain size with distance to Saturn as observed by the VIMS-experiment on board the Cassini spacecraft can be found by our estimates and implications for the saturnian system will be addressed. Y1 - 2006 UR - http://www.sciencedirect.com/science/journal/00191035 U6 - https://doi.org/10.1016/j.icarus.2005.10.011 SN - 0019-1035 ER - TY - JOUR A1 - Albertini, Francesca Yardenit T1 - Bagdad und Jerusalem als "Städte des Friedens" nach der frühmittelalterlichen Religionsphilosophie im Judentum und im Islam Y1 - 2006 ER - TY - JOUR A1 - Albertini, Francesca Yardenit T1 - Jüdische Theologie und Ethik Y1 - 2006 ER - TY - JOUR A1 - Albertini, Francesca Yardenit T1 - Die Wirtschaftsethik aus jüdischer Sicht : der Aufstand der Armen als Herausforderung des 21. Jahrhunderts Y1 - 2006 SN - 0022-572X ER - TY - JOUR A1 - Albertini, Francesca Yardenit T1 - Hiob 2,1 - 7a: Aspekte zur "Wette" zwischen Gott und dem Satan in der jüdischen Philosophie des Mittelalters un der Neuzeit Y1 - 2006 ER - TY - JOUR A1 - Albertini, Francesca Yardenit T1 - Die religiöse und geschichtliche Gestalt Jesus von Nazareth im Denken Moses Maimonides Y1 - 2006 ER - TY - JOUR A1 - Albertini, Francesca Yardenit T1 - Theologie und Geschichtsphilosophie am Jüdisch-Theologischen Seminar in Breslau : der Fall von Baruch Spinoza Y1 - 2006 ER -