Leibniz University of Hanover

About: Leibniz University of Hanover is a education organization based out in Hanover, Niedersachsen, Germany. It is known for research contribution in the topics: Finite element method & Computer science. The organization has 14283 authors who have published 29845 publications receiving 682152 citations.

Observation of a kilogram-scale oscillator near its quantum ground state

Abstract: We introduce a novel cooling technique capable of approaching the quantum ground state of a kilogram-scale system—an interferometric gravitational wave detector. The detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) operate within a factor of 10 of the standard quantum limit (SQL), providing a displacement sensitivity of 10−18 m in a 100 Hz band centered on 150 Hz. With a new feedback strategy, we dynamically shift the resonant frequency of a 2.7 kg pendulum mode to lie within this optimal band, where its effective temperature falls as low as 1.4 μK, and its occupation number reaches about 200 quanta. This work shows how the exquisite sensitivity necessary to detect gravitational waves can be made available to probe the validity of quantum mechanics on an enormous mass scale.

Dynamics of oscillators with impact and friction

Abstract: In the present paper two types of nonsmooth oscillators are investigated: an impact oscillator and a self-sustained friction oscillator. Both are nonsmooth one degree of freedom oscillators with harmonic external excitation. Here the different types of motion, bifurcation diagrams and Poincare maps are determined from experiments. These results will be compared with numerical results on the basis of the identified impact and friction models. The nonsmooth third-order systems show rich bifurcational behaviour which is analysed by numerical simulations but also using mapping approaches. Two different formalisms for the calculation of the Lyapunov exponents are applied. The latter one requires special considerations in the given case of nonsmooth systems. Furthermore, the embedding dimension is gained applying the method of false nearest neighbours. In the case of coexisting solutions further analysis is done by means of bifurcation and stability analysis and the cell-mapping approach.

What is the Value of Luxury? A Cross‐Cultural Consumer Perspective

Abstract: International luxury businesses are challenged by the identification and satisfaction of the common needs and desires of global market segments. Although luxury goods have become available to a wider range of consumers, the traditional conspicuous consumption model has been transformed into a new experiential luxury sensibility that is marked by a change in the way that consumers define luxury. Based on an empirical study in collaboration with American, European, and Asian researchers, the results provide evidence that consumers in various parts of the world purchase or wish to purchase luxury products for varied reasons but that such consumers generally possess similar values. Regardless of their countries of origin, the basic motivational drivers of luxury consumers are similar among the financial, functional, personal, and social dimensions of luxury value perceptions, although the relative importance of these dimensions varies.

In situ synthesis of MOF membranes on ZnAl-CO3 LDH buffer layer-modified substrates

Abstract: We develop here a urea hydrolysis method to in situ prepare asymmetric ZnAl-CO3 layered double hydroxide (LDH) buffer layers with various stable equilibrium morphology on porous Al2O3 substrates. In particular it is found that well-intergrown ZIF-8 membranes can be directly synthesized on the ZnAl-CO3 LDH buffer layer-modified substrates, owing to the specific metal–imidazole interaction between ZnAl-CO3 LDHs and ZIF-8. Other Zn-based MOF membranes, like ZIF-7 and ZIF-90, can also be synthesized with this method. Our finding demonstrates that LDH buffer layer represents a new concept for substrate modification.

Phase Relations and Liquid Lines of Descent in Hydrous Ferrobasalt—Implications for the Skaergaard Intrusion and Columbia River Flood Basalts

Abstract: Crystallization experiments using a hydrous ferrobasalt as starting material, conducted at 200MPa, 940^12008C, at a wide range of water activities (0 1^1) and redox conditions (QFM 3 to QFMþ 4, where QFM is the quartz^fayalite^magnetite oxygen buffer), show that H2O influences significantly the differentiation history of ferrobasaltic magmas. A combination of our data with published experiments on dry ferrobasalt at 1atm provides an extensive experimental database for modeling and quantifying crystallization and differentiation processes within a typical Fe-rich tholeiitic system under both dry and hydrous conditions.The addition of H2O decreases liquidus temperatures and changes significantly the proportions, temperature range and sequence of crystallizing mineral phases. The dry liquidus is at about 11708C whereas the liquidus for H2O-saturated melts is at 10608C.The main phases crystallizing from H2O-bearing ferrobasalt at the investigated conditions are olivine (OL), clinopyroxene (CPX), plagioclase (PL), magnetite (MT), hematite (HM), ilmenite (ILM) and amphibole (AM). The phase assemblage is similar to that of the dry system except for the presence of HM at extremely oxidizing conditions and AM at low temperatures (59508C) and H2O-saturated conditions. The important observation made in this study is that the stability of Fe^Ti-oxides, and in particular MT, as well as the simultaneous coprecipitation of MTand ILM, are almost independent of the activity of H2O (aH2O) in the system, whereas the liquidus temperatures of the silicate minerals are dramatically depressed by increasing aH2O.The stabilities of oxides are controlled mainly by the redox conditions prevailing in the system.The most pronounced effect of aH2O on the liquidus temperatures of silicates is observed for PL, which shows a considerable delay in crystallization with progressive magma differentiation. Early crystallization of Fe^Ti-oxides in H2O-bearing ferrobasaltic compositions precludes any significant Fe enrichment during differentiation. As Fe enrichment is a characteristic feature of the Skaergaard intrusion, it implies that the Skaergaard parental magma did not contain considerable amounts of water. On the other hand, our experiments indicate that the differentiation of some ferrobasaltic series from the Columbia River flood basalt province might have occurred in magmatic systems containing significant amounts of volatiles ( 0 5^3 wt%H2O).