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951.
Karl-Robert Deibel Fabian KaiserRemo Zimmermann Linus MeierPeter Bolt Konrad Wegener 《Ultrasonics》2014
Ultrasonic vibration assisted cutting is a complex process with high dynamics. The interaction between cutting tool and workpiece is of key interest to understand the entire process. Experimental investigations are limited by the dynamics of the measurement system, and thus appropriately modeling of the ultrasonic vibration assisted cutting process is essential. In this investigation, a dynamic model regarding the ultrasonic vibration assisted guillotining of stacked paper sheets is developed. A Kelvin–Voigt material model, representing the individual sheets, is chosen, with its stiffness and damping parameters being empirically determined. A novel measurement strategy for studying the contact time and interaction between cutting tool and workpiece is introduced. It allows the verification of the highly dynamic behavior of the developed model. With the dynamic model, the experimentally observed cutting forces can be calculated. It is found that the dynamic forces cause a quicker failure of the material, which leads to a lower compression of the stack prior to reaching the critical cutting force. 相似文献
952.
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954.
Fabian Fertig Karin Krauß Johannes Greulich Florian Clement Daniel Biro Ralf Preu Stefan Rein 《固体物理学:研究快报》2014,8(5):381-384
The BOSCO solar cell represents a bifacial structure with double‐sided collection. The structure allows the use of standard module interconnection technology and favours the use of material with low to medium diffusion length and low resistivity for maximum benefit towards other structures, such as Al‐BSF and PERC. Within this work, we present first results on different multicrystalline silicon materials yielding a monofacial efficiency of 17.4% on large‐area wafers from block‐cast mc‐Si. This value represents a gain of ~0.7%abs compared to Al‐BSF cells processed in parallel. The applicability for bifacial operation is demonstrated by a significantly increased quantum efficiency for rear side illumination. These results make the BOSCO solar cell concept a promising candidate to further boost the output of utility‐scale PV plants even when using low‐cost wafers of low to medium diffusion length material.
955.
Efficient and reliable home delivery is crucial for the economic success of online retailers. This is especially challenging for attended home deliveries in metropolitan areas where logistics service providers face congested traffic networks and customers expect deliveries in tight delivery time windows. Our goal is to develop and compare strategies that maximize the profits of a logistics service provider by accepting as many delivery requests as possible, while assessing the potential impact of a request on the service quality of a delivery tour. Several acceptance mechanisms are introduced, differing in the amount of travel time information that is considered in the decision of whether a delivery request can be accommodated or not. A real-world inspired simulation framework is used for comparison of acceptance mechanisms with regard to profits and service quality. Computational experiments utilizing this simulation framework investigate the effectiveness of acceptance mechanisms and help identify when more advanced travel time information may be worth the additional data collection and computational efforts. 相似文献
956.
Mid-to-late transition metal complexes that feature terminal, multiply bonded ligands such as oxos, imides, and nitrides have been invoked as intermediates in several catalytic transformations of synthetic and biological significance. Until about ten years ago, isolable examples of such species were virtually unknown. Over the past decade or so, numerous chemically well-defined examples of such species have been discovered. In this context, the presentreview summarizes the development of 4- and 5-coordinate Fe(E) and Co(E) species under local three-fold symmetry. 相似文献
957.
Ruben Bartholomäus Fabian Dommershausen Dr. Markus Thiele Narayan S. Karanjule Dr. Klaus Harms Prof. Dr. Ulrich Koert 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(23):7423-7436
A total synthesis of the proposed structures of fulicineroside and its aglycone fulicinerine is reported. The tetrasubstituted dibenzofuran substructure was accessible either through a Pd‐mediated ortho‐metalation or by an Ir‐catalyzed meta‐borylation. The synthesis of the β,β,α‐linked trisaccharide consisting of D ‐olivose, L ‐rhodinose, and L ‐rhamnose was challenged by the unprecedented β‐linked rhodinose. A Pd‐catalyzed β‐selective glycosylation of a 4‐epi‐rhodinose and a subsequent Mitsunobu inversion provided selectively the β‐linked L ‐rhodinose‐L ‐rhamnose disaccharide. Comparison with the reported data for the natural product and the aglycone suggests a misassignment of the structure of the natural product. 相似文献
958.
Irén Fischer Dr. Adrien Kaeser Mauraline A. M. Peters‐Gumbs Dr. Albertus P. H. J. Schenning 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(33):10928-10934
Fluorescent nanoparticles based on π‐conjugated small molecules and polymers are two different classes of π‐conjugated systems that have attracted much interest. To date, both emerging classes have only been studied separately and showed no clear differences in their properties. Herein these nanoparticles are compared on the basis of a fluorene co‐polymer and its corresponding small molecule. Both systems formed nanoparticles with the same diameter, whereas the fluorescence properties clearly differed. In case of the polymer the fluorescence diminished, whereas for the small molecules the fluorescence increased. In addition, the capability of encapsulation and release of a hydrophobic dye from the fluorescent nanoparticles was studied. For the polymer system, encapsulation was highly efficient and no release was observed, whereas for the small molecule system encapsulation was less efficient and release of the dye was observed. These studies show a clear difference between small molecules and polymers which has important implications for the design of fluorescent nanoparticles. 相似文献
959.
W. Kuchen D. Langsch W. Peters 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):55-61
Abstract P.P-Dialkylthiophosphinsäureamide R2P(S)NHR' (R=Me, 'Pr, 'Bu; R'=Me, Et, iPr. cHex. tBu. Ph. etc.) wurden erhalten durch Umsetzung von R2PNHR' mit Schwefel oder durch Reaktion von Me2P(S)CI mit primaren Aminen. Ihre 31P- und 13C-NMR-Spektren werden diskutiert. Insbesondere die Di-t-butylthiophosphinsäureamide sind auszilg;ergewöhnlich stabil gegen Hydrolyse und Luftsauerstoff. P,P-Dialkylthiophosphinic acid amides R2P(S)NHR' (R=Me. iPr. tBu; R'=Me, Et, iPr, cHex. tBu, Ph. etc.) have been obtained by reaction of the corresponding aminophosphines with sulfur or by reaction of dimethylthiophosphorylhalides with primary amines. Their 31P- and 13C-NMR spectra are discussed. The di-t-butylthiophosphinic compounds proved to be remarkably stable against moisture and oxygen. 相似文献
960.
J. Fabian P. Schönfeld R. Mayer 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):151-153
Abstract The significantly enhanced acidity of C[sbnd]H bonds attached to a σ-bivalent sulfur atom can be explained without taking into account the octet expansion of sulfur. The higher carbanion stabilization effect of sulfur in comparison to oxygen has been related to the greater capability of the σ-bivalent sulfur to take up excess charge into the sp-valence shell. 相似文献