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991.
Marcel Müri Bernd Gotsmann Yann Leroux Marius Trouwborst Emanuel Lörtscher Heike Riel Marcel Mayor 《Advanced functional materials》2011,21(19):3706-3714
Due to the increasing importance of modified electrodes for many applications in nanotechnology, including molecular electronics, bioelectronics, and sensors, there is a need to find ways to chemically attach suitable molecular films onto the electrodes. Combining the electroreduction of aryl diazonium salts with the Sonogashira cross‐coupling reaction, a new modular technique to modify electrodes is presented. The new technique allows a wide range of functional groups to be introduced onto electrode surfaces with high surface coverage by the functional subunit. Various organic subunits, including redox chromophores, are successfully attached to platinum electrodes. The corresponding films are characterized using cyclic voltammetry, X‐ray photoelectron spectroscopy, atomic force microscopy, and contact‐angle measurements. The electroreduction of diazonium salts is successfully achieved on a broad variety of conducting and semiconducting surfaces, which shows that the technique is applicable to a broad variety of substrates. 相似文献
992.
Martijn Kuik Gert‐Jan A. H. Wetzelaer Jurre G. Laddé Herman T. Nicolai Jurjen Wildeman Jörgen Sweelssen Paul W. M. Blom 《Advanced functional materials》2011,21(23):4502-4509
The effect of on‐chain ketone defects on the charge transport of the polyfluorene derivative poly(9,9‐dioctylfluorene) (PFO) is investigated. Using MoO3 as ohmic hole contact, the hole transport in a pristine PFO diode is observed to be limited by space‐charge, whereas fluorenone contaminated PFO (PFO‐F) is shown to be trap limited by the occurrence of an exponential trap distribution with a trap depth of 0.18 eV. The electron transport in PFO is also observed to be trap limited, but in order to describe the electron transport of PFO‐F, an additional trap level with a depth of 0.46 eV must be introduced. The obtained energy levels of the fluorenone trapping sites are in close agreement with cyclic voltammetry (CV) measurements reported in literature. As a result, the fluorenone defects are shown to simultaneously act as hole‐ and electron trap. Moreover, through ideality factor measurements, the green emission associated with these defects is observed to originate from trap‐assisted recombination. 相似文献
993.
Luigi Catuogno Hans Löhr Mark Manulis Ahmad-Reza Sadeghi Christian Stüble Marcel Winandy 《Datenschutz und Datensicherheit - DuD》2010,34(5):289-294
Trusted Virtual Domains (TVDs) provide a secure IT infrastructure offering a homogeneous and transparent enforcement of access
control policies on data and network resources. In this article, we give an overview of the fundamental ideas and basic concepts
behind TVDs, present a realization of TVDs, and discuss application scenarios. 相似文献
994.
James P.G. Sterbenz David Hutchison Egemen K. Çetinkaya Abdul Jabbar Justin P. Rohrer Marcus Schöller Paul Smith 《Computer Networks》2010,54(8):1245-1265
The Internet has become essential to all aspects of modern life, and thus the consequences of network disruption have become increasingly severe. It is widely recognised that the Internet is not sufficiently resilient, survivable, and dependable, and that significant research, development, and engineering is necessary to improve the situation. This paper provides an architectural framework for resilience and survivability in communication networks and provides a survey of the disciplines that resilience encompasses, along with significant past failures of the network infrastructure. A resilience strategy is presented to defend against, detect, and remediate challenges, a set of principles for designing resilient networks is presented, and techniques are described to analyse network resilience. 相似文献
995.
Mikael Wahlström Miika Aittala Helinä Kotilainen Tiina Yli-Karhu Janne Porkka Esa Nykänen 《Virtual Reality》2010,14(3):197-211
Several studies indicate that virtual reality (VR) systems are useful for end-user participation in an environmental design
process. However, these systems can be costly and thus support for the decision whether to invest in a VR of some type is
useful. This study presents a novel method for analysing the usefulness of a VR system for the purpose of end-user participation.
We collected qualitative end-user opinion data in the real environment and then contrasted this data with the capabilities
of a VR system. Additionally, to better understand the capabilities of the VR used, we examined how the end-users perceive
the used virtual environment, which in this case was CAVE, an immersive VR system where projectors are directed to the walls
of a room-sized cube. In this way, we analysed whether the same functions and elements identified by end-users on the actual
wards could also be evaluated in the CAVE. Eleven nurses and 11 patients participated in the study by evaluating a bathroom
and/or four patient rooms modelled by the CAVE and the actual hospital wards. The CAVE was convenient for evaluating most
issues identified by the study participants in the actual hospital wards, i.e. aesthetics; correct location of equipment,
supplies and materials; distraction by or the good companion of other patients as well as window position and size and living/workspace.
However, it was not possible to evaluate with full certainty the possibilities for bracing against grab bars or other objects
in the VR, and this was found to be relevant to the independent functioning of patients with limited mobility. Also, due to
the relatively low luminance levels of projectors, evaluations regarding lighting were considered unreliable. Moreover, end-users
were not always certain about the sizes and sufficiency of space in the CAVE. Solutions to overcome these limitations were
proposed. 相似文献
996.
Owing to the influence of two‐dimensional heat transfer, fire tests and heat transfer calculations show that charring on the narrow side of rectangular timber cross‐sections may be considerably greater than charring on the wide side. For timber members unprotected throughout the time of fire exposure as well as members initially protected from fire exposure, it is shown by calculation, that the relationship between charring on the narrow side and time is nonlinear. In order to take into account increased charring on the narrow side of timber members a section factor ks was determined. By calculation it is shown that bending moment resistance is only insignificantly influenced by the effect of two‐dimensional heat transfer and the factor ks can therefore be neglected, making the fire design of timber members easier. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
997.
D. Habel O. Görke M. Tovar M. Willinger M. Ziemann O. Schwarz R. Schomäcker H. Schubert 《Journal of the European Ceramic Society》2009,29(6):1093-1099
Commonly used catalysts in industry are compositions of highly dispersed particles. Typical systems consist of precious metals or transition metal oxides like V2O5 on oxide supports, especially TiO2, Al2O3 and SiO2. Support and active compound show a different chemical and material behaviour. A very important influence of the support on the active compound is the formation of microstrains due to the different thermal expansion behaviour. On the surface of a stiff linear elastic support the active compound is certainly strain hindered. In order to monitor the development of strain hindrance and further effects, in situ experiments were carried out at temperature both in an X-ray and in a neutron powder diffractometer. The width of the reflexes indicated a strong influence of the thermal expansion mismatch on peak width. The strain hindrance creates mismatch stresses high enough to overcome the yield stress of V2O5. The Williamson–Hall plots showed both a particle size effect as well as a stress widening but the measurements were difficult because of the materials anisotropy. The TEM work showed again very fine particles which agrees with the X-ray measurements. The support effect may be seen as thermal stress induced formation of a mosaic structure in the active compound. Moreover, the peak width correlated with the catalytic activity. The low ordered regimes in the mosaic structure are acting as further active centres for the catalytic reaction. 相似文献
998.
Ibrahim Onifade Yared Dinegdae Björn Birgisson 《Frontiers of Structural and Civil Engineering》2017,11(3):257-269
In this paper, a hierarchical approach is proposed for the evaluation of fatigue cracking in asphalt concrete pavements considering three different levels of complexities in the representation of the material behaviour, design parameters characterization and the determination of the pavement response as well as damage computation. Based on the developed hierarchical approach, three damage computation levels are identified and proposed. The levels of fatigue damage analysis provides pavement engineers a variety of tools that can be used for pavement analysis depending on the availability of data, required level of prediction accuracy and computational power at their disposal. The hierarchical approach also provides a systematic approach for the understanding of the fundamental mechanisms of pavement deterioration, the elimination of the empiricism associated with pavement design today and the transition towards the use of sound principles of mechanics in pavement analysis and design. 相似文献
999.
1000.
U. Götze Th. Weber C. Linke A. Schmidt 《Materialwissenschaft und Werkstofftechnik》2009,40(7):566-572
Target Costing for Materials – Potentialities and Methodology Target Costing is a standard instrument of cost management in business administration, but hardly mentioned in the economic oriented literature on material sciences. Nevertheless there are high potentialities for developers, producers, or users of materials regarding the improvement of efficiency. Therefore, this article will present these potentialities of a material oriented Target Costing. Besides, the general methodology of Target Costing will be modified to meet the specifics of materials from the perspectives of users of materials on the one hand and developers respectively producers of materials on the other. 相似文献