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451.
452.
Francesco Laccone Luigi Malomo Maurizio Froli Paolo Cignoni Nico Pietroni 《Computer Graphics Forum》2020,39(1):260-273
We propose an optimization algorithm for the design of post-tensioned architectural shell structures, composed of triangular glass panels, in which glass has a load-bearing function. Due to its brittle nature, glass can fail when it is subject to tensile forces. Hence, we enrich the structure with a cable net, which is specifically designed to post-tension the shell, relieving the underlying glass structure from tension. We automatically derive an optimized cable layout, together with the appropriate pre-load of each cable. The method is driven by a physically based static analysis of the shell subject to its service load. We assess our approach by applying non-linear finite element analysis to several real-scale application scenarios. Such a method of cable tensioning produces glass shells that are optimized from the material usage viewpoint since they exploit the high compression strength of glass. As a result, they are lightweight and robust. Both aesthetic and static qualities are improved with respect to grid shell competitors. 相似文献
453.
Sven Annas Michael Elfering Nico Volbert Hans‐Arno Jantzen Jürgen Scholz Uwe Janoske 《化学,工程师,技术》2019,91(7):969-979
The development of agitators in biogas plants is based on empirical values. Here, the influence of altered agitator positions and fluid properties on the flow field of a paddle agitator was examined by particle image velocimetry (PIV) measurements. The viscosity characteristics of fermenter slurries were analyzed by a pipe viscometer to adapt the viscosity characteristics of a model fluid with regards to similarity laws. An altered position reduces the dead zones significantly by up to 55 %. 相似文献
454.
Wirsing Tobias Kühlers Dirk Maier Matthias Schönthal Michael Roth Karl Goldscheider Nico 《Grundwasser》2018,23(3):219-232
Grundwasser - Die ökologisch nachhaltige Bewirtschaftung von Grundwasservorkommen zum Schutz grundwasserabhängiger Ökosysteme ist gesetzlich vorgeschrieben. In der aktuellen... 相似文献
455.
We report on the fabrication of hexagonally ordered, sub-wavelength hole arrays (SWHA) by colloidal lithography combined with reactive ion etching and a lift-off process, and their characterization with scanning electron microscopy and ellipsometry. 相似文献
456.
Z Yu S Blaak ZY Chang J Yao JG Bosch C Prins CT Lancée N de Jong MA Pertijs GC Meijer 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2012,59(7):1500-1512
There is a clear clinical need for creating 3-D images of the heart. One promising technique is the use of transesophageal echocardiography (TEE). To enable 3-D TEE, we are developing a miniature ultrasound probe containing a matrix piezoelectric transducer with more than 2000 elements. Because a gastroscopic tube cannot accommodate the cables needed to connect all transducer elements directly to an imaging system, a major challenge is to locally reduce the number of channels, while maintaining a sufficient signal-to-noise ratio. This can be achieved by using front-end receiver electronics bonded to the transducers to provide appropriate signal conditioning in the tip of the probe. This paper presents the design of such electronics, realizing time-gain compensation (TGC) and micro-beamforming using simple, low-power circuits. Prototypes of TGC amplifiers and micro-beamforming cells have been fabricated in 0.35-μm CMOS technology. These prototype chips have been combined on a printed circuit board (PCB) to form an ultrasound-receiver system capable of reading and combining the signals of three transducer elements. Experimental results show that this design is a suitable candidate for 3-D TEE. 相似文献
457.
Nico Hotz Nurten Koc Timo Schwamb Niklas C. Schirmer Dimos Poulikakos 《American Institute of Chemical Engineers》2009,55(7):1849-1859
In this study, a novel flow‐based method is presented to place catalytic nanoparticles into a reactor by sol‐gelation of a porous ceramic consisting of Rh/ceria/zirconia nanoparticles, silica sand, ceramic binder, and a gelation agent. This method allows for the placement of a liquid precursor containing the catalyst into the final reactor geometry without the need of impregnating or coating of a substrate with the catalytic material. The so generated foam‐like porous ceramic shows properties highly appropriate for use as catalytic reactor material, e.g., reasonable pressure drop due to its porosity, high thermal and catalytic stability, and excellent catalytic behavior. To investigate the catalytic activity, microreactors containing this foam‐like ceramic are employed for the production of hydrogen and carbon monoxide‐rich syngas from butane. The effect of operating parameters such as the inlet flow rate on the hydrocarbon processing is analyzed and the limitation of the reactor by diffusion mass transport is investigated. © 2009 American Institute of Chemical Engineers AIChE J, 2009 相似文献
458.
D. N. Abdurashitov V. N. Gavrin V. L. Matushko M. F. Mustafin A. A. Shikhin I. E. Veretenkin V. E. Yants J. S. Nico A. K. Thompson 《Instruments and Experimental Techniques》2009,52(1):25-32
Development of a capture gated spectrometer on the basis of a liquid organic scintillator doped with enriched 6Li is discussed. Particular interest is evoked by the good pulse height resolution of the spectrometer for 14-MeV neutrons, which is expected to be very high, ~10–15%. This resolution is attained by compensating for the nonlinearity of the light yield in the scintillator owing to the use of separate optically isolated sections, which independently detect scintillations from each recoil proton. The detector is sensitive to fluence rates ranging from 10?4 to 102 cm?2 s?1 above a threshold of 500 keV under conditions of uncorrelated γ-ray background at a level of up to 102 s?1 (E > 100 keV). A pilot model of the detector based on a scintillator without a lithium dopant has been produced and tested. The detector efficiency is governed by the scintillator volume (~1.2 l); for 3-MeV neutrons, its value is 0.2–0.5%. The response of the pilot detector to neutrons from a Pu-α-Be source with energies of up to 10 MeV has been measured. Initial testing indicates a low threshold at an ~600-keV energy of a recoil proton. A good spectral response is obtained using the criterion that three optical sections of the detector operate at a time. This spectrometer can find application in low-background experiments in basic physics research, as well as in space research and nuclear medicine for measuring the parameters of the neutron flux. 相似文献
459.
Chengkun Song Nico Kerber Jan Rothörl Yuqing Ge Klaus Raab Boris Seng Maarten A. Brems Florian Dittrich Robert M. Reeve Jianbo Wang Qingfang Liu Peter Virnau Mathias Kläui 《Advanced functional materials》2021,31(19):2010739
Magnetic skyrmions are topological magnetic structures, which exhibit quasi-particle properties and can show enhanced stability against perturbation from thermal noise. Recently, thermal Brownian diffusion of these quasi-particles has been found in continuous films, and unconventional computing applications have received significant attention, requiring structured elements. Thus, as the next necessary step, skyrmion diffusion in confined geometries is studied, and it is found to be qualitatively different: The diffusion is governed by the interplay between the total number of skyrmions and the structure geometry. In particular, the effect of circular and triangular geometrical confinement is ascertained. It is found that for triangular geometries, the behavior is drastically different for the cases when the number of skyrmions in the element is either commensurate or incommensurate with a symmetric filling of the element. This influence of commensurability is corroborated by simulations of a quasi-particle model. 相似文献
460.
Boris Seng Daniel Schönke Javier Yeste Robert M. Reeve Nico Kerber Daniel Lacour Jean-Loïs Bello Nicolas Bergeard Fabian Kammerbauer Mona Bhukta Tom Ferté Christine Boeglin Florin Radu Radu Abrudan Torsten Kachel Stéphane Mangin Michel Hehn Mathias Kläui 《Advanced functional materials》2021,31(33):2102307
The evolution of chiral spin structures is studied in ferrimagnetic Ta/Ir/Fe/GdFeCo/Pt multilayers as a function of temperature using scanning electron microscopy with polarization analysis (SEMPA). The GdFeCo ferrimagnet exhibits pure right-handed Néel-type domain wall (DW) spin textures over a large temperature range. This indicates the presence of a negative Dzyaloshinskii–Moriya interaction that can originate from both the top Fe/Pt and the Co/Pt interfaces. From measurements of the DW width, as well as complementary magnetic characterization, the exchange stiffness as a function of temperature is ascertained. The exchange stiffness is surprisingly more or less constant, which is explained by theoretical predictions. Beyond single skyrmions, it is identified by direct imaging a pure Néel-type skyrmionium, which due to the expected vanishing skyrmion Hall angle, is a promising topological spin structure to enable applications by next generation of spintronic devices. 相似文献