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81.
82.
Antoine Debuigne Marie HurtgenChristophe Detrembleur Christine JérômeChristopher Barner-Kowollik Thomas Junkers 《Progress in Polymer Science》2012,37(7):1004-1030
The current review focuses on the relevance and practical benefit of interpolymer radical coupling methods. The latter are developing rapidly and constitute a perfectly complementary macromolecular engineering toolbox to the controlled radical polymerization techniques (CRP). Indeed, all structures formed by CRP are likely to be prone to radical coupling reactions, which multiply the available synthetic possibilities. Basically, the coupling systems can be divided in two main categories. The first one, including the atom transfer radical coupling (ATRC), silane radical atom abstraction (SRAA) and cobalt-mediated radical coupling (CMRC), relies on the recombination of macroradicals produced from a dormant species. The second one, including atom transfer nitroxide radical coupling (ATNRC), single electron transfer nitroxide radical coupling (SETNRC), enhanced spin capturing polymerization (ESCP) and nitrone/nitroso mediated radical coupling (NMRC), makes use of a radical scavenger in order to promote the conjugation of the polymer chains. More than a compilation of macromolecular engineering achievements, the present review additionally aims to emphasize the particularities, synthetic potential and present limitations of each system. 相似文献
83.
André Lecomte Jean-Michel Mechling Cécile Diliberto 《Construction and Building Materials》2009,23(10):3279-3286
Knowing the virtual packing densities of all the components in a mixture is necessary to calculate its granular packing density with the compressible packing model. The calculation of these virtual packing densities is based on real packing density measurements carried out according to specific operating modes, each one with a different compaction index K. For powders, the current method consists in adding water to powder in a mixer until obtaining a smooth paste (K = 6.7). But this method remains subjective since the degree of smoothness achieved is estimated by the operator. The objective of this work is to put forward a more rational alternative method based on tests of normal consistency used in cement plants. This paper presents experiments on binary mixtures (cement–mineral admixtures), with or without superplasticizer, which have resulted in a compaction index K = 4.8. Using these results, the amount of water (given in the technical data sheet) needed to obtain a normal consistency allows the calculation of virtual packing densities of standardized cements. However, if a superplasticizer is used it is necessary to carry out this test. Its saturation proportion can also be estimated with the test of normal consistency. 相似文献
84.
This paper proposes an original numerical method and studies its performance for solving high-frequency scattering problems involving elongated scatterers. The approach is based on coupling a high-order Padé-type non-reflecting boundary condition with plane wave finite element formulations. It is shown that for some numerical examples the approximate solution of suitable accuracy can be obtained using a small number of degrees of freedom. 相似文献
85.
Paule Njiwa Clotilde Minfray Thierry Le Mogne Béatrice Vacher Jean-Michel Martin Shigeki Matsui Masaru Mishina 《Tribology Letters》2011,44(1):19-30
In this study, we are interested in the anti-wear properties of zinc dialkyl phosphate additive (ZP) in comparison with ‘classical’ zinc dialkyldithiophosphate (ZDDP). Friction tests were performed on a reciprocating tribometer using both ball-on-flat and cylinder-on-flat configurations
under a Hertzian contact pressure of 0.9 GPa. Experiments were carried out as a function of temperature (25 and 100 °C), sliding
speed (25, 50 and 100 mm/s) and additives concentrations. Ball wear scar diameters as well as friction coefficient were measured.
In order to better understand the anti-wear mechanisms of these additives, friction tests were followed by surface analyses
such as AES (Auger Electron Spectroscopy) and XPS (X-Ray Photoelectron Spectroscopy). Transmission Electron Microscopy (TEM)
observations of the ZDDP and ZP tribofilms were also carried out to visualise the generated layers. The anti-wear capability of ZP molecule is discussed. 相似文献
86.
News
Fifth International Deer Biology Congress 相似文献87.
Effects of club size in the provision of public goods. Network and congestion effects in the case of the French municipalities 总被引:2,自引:0,他引:2
The article formalizes and measures the impact of club size on the quality of the public good provided to its members. Under
a general framework we describe various functional forms that allow either network or crowding effects. Mechanisms of provision
are that of a political process in which both the demand and the supply sides are considered. Estimations use the whole set
of French municipalities. The supply model performs better than the demand model in the case of small municipalities, while
for large cities the demand model has higher explanatory power. In so far as impact of city size on the quality of club goods
is concerned, crowding does appear, but it does so in different patterns. For small towns marginal congestion first decreases
then increases with population. Marginal congestion is decreasing for cities of intermediate size. For larger cities no significant
effects are observed.
Received: 27 June 2000 / Accepted: 20 August 2001
RID="*"
ID="*" We have received particularly helpful comments from the editor-in-chief and two anonymous referees. We also thank Danièle
Moret-Bailly for her friendly computational assistance. 相似文献
88.
The quality of the image produced by an outdoor optical system is affected by the presence of atmospheric aerosols between object and receiver. The properties of the point-spread function that result from aerosol particles were calculated by a new Monte Carlo code called MEDIA (an acronym for Modélisation des Effets de Diffusion Inhérents à l'Atmosphère). The influence of the scattering phase function's angular dependence on the irradiance of the focal plane of a detector was studied. Calculations were performed by use of Mie theory and of the Henyey-Greenstein formulation for the same asymmetry parameter and various detector optical characteristics and atmospheric conditions. Major variations were observed for strong forward-peaked scattering phase functions and a large detector field of view. 相似文献
89.
The Basic Linear Algebra Subprograms (BLAS) define one of the most heavily used performance‐critical APIs in scientific computing today. It has long been understood that the most important of these routines, the dense Level 3 BLAS, may be written efficiently given a highly optimized general matrix multiply routine. In this paper, however, we show that an even larger set of operations can be efficiently maintained using a much simpler matrix multiply kernel. Indeed, this is how our own project, ATLAS (which provides one of the most widely used BLAS implementations in use today), supports a large variety of performance‐critical routines. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
90.
Jean-Christophe Zufferey Alexis Guanella Antoine Beyeler Dario Floreano 《Autonomous Robots》2006,21(3):243-254
Because of their ability to naturally float in the air, indoor airships (often called blimps) constitute an appealing platform
for research in aerial robotics. However, when confronted to long lasting experiments such as those involving learning or
evolutionary techniques, blimps present the disadvantage that they cannot be linked to external power sources and tend to
have little mechanical resistance due to their low weight budget. One solution to this problem is to use a realistic flight
simulator, which can also significantly reduce experimental duration by running faster than real time. This requires an efficient
physical dynamic modelling and parameter identification procedure, which are complicated to develop and usually rely on costly
facilities such as wind tunnels. In this paper, we present a simple and efficient physics-based dynamic modelling of indoor
airships including a pragmatic methodology for parameter identification without the need for complex or costly test facilities.
Our approach is tested with an existing blimp in a vision-based navigation task. Neuronal controllers are evolved in simulation
to map visual input into motor commands in order to steer the flying robot forward as fast as possible while avoiding collisions.
After evolution, the best individuals are successfully transferred to the physical blimp, which experimentally demonstrates
the efficiency of the proposed approach.
Jean-Christophe Zufferey and Alexis Guanella contributed equally to this work. 相似文献