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71.
On a novel expression of the field scattered by an arbitrary constant impedance plane 总被引:1,自引:0,他引:1
J.M.L. Bernard 《Wave Motion》2011,48(7):635-646
The electromagnetic field scattered by an impedance plane is generally given by its plane wave expansion (Fourier representation). Here we derive an alternative expression which is more suitable for point source illumination. For this, we consider an original expression of the Hertz potentials for the incident field and express the scattered potentials in a novel form. A special function then involved can be expressed in an integral which is in turn expanded in a convergent series. The expression presented also permits us to express complete asymptotics. Our development considers an arbitrary impedance, passive or active. 相似文献
72.
J. Co?r C. Bernard H. Laurent A. Andrade-Campos S. Thuillier 《Experimental Mechanics》2011,51(7):1185-1195
The temperature influence on the mechanical behaviour during plastic deformation of an AA5754-O aluminium alloy has been investigated by several experimental tests. First, monotonous tensile tests were carried out from room temperature up to 200°C with a classical tensile machine and with a less conventional testing apparatus involving the heating of the sample by Joule effect. With this second testing apparatus, the strain fields and tensile curves were obtained in function of temperature by means of a non-contacting optical 3D deformation measuring system. Moreover, shear tests were performed in the same temperature range. It is shown that the anisotropy coefficients are rather constant within this temperature range, with a relative variation less than 8%. For both tensile and shear tests, the stress levels are similar at the beginning of straining at room temperature and 150°C, except that the Portevin?CLe Chatelier (PLC) phenomenon disappears at elevated temperature, and then evolves differently. At 200°C, the stress level is clearly below whatever the deformation. In the framework of drawing process, the formability of this alloy at temperatures higher than 150°C seems to be improved. 相似文献
73.
François Bentosela Horia D. Cornean Bernard H. Fleury Nicola Marchetti 《Mathematical Methods in the Applied Sciences》2011,34(8):963-976
We develop a deterministic ab initio model for the input–output relationship of a multiple‐input multiple‐output (MIMO) wireless channel, starting from the Maxwell equations combined with Ohm's law. The main technical tools are scattering and geometric perturbation theories. The derived relationship can lead us to a deep understanding of how the propagation conditions and the coupling effects between the elements of multiple‐element arrays affect the properties of an MIMO channel, e.g. its capacity and its number of degrees of freedom. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
74.
We study the relationship between the Ferrers property and the notion of interval order in the context of valued relations.
Given a crisp preference structure without incomparability, the strict preference relation satisfies the Ferrers property
if and only if the associated weak preference relation does. These conditions characterize a total interval order. For valued
relations the Ferrers property can be written in two different and non-equivalent ways. In this work, we compare these properties
by finding the kind of completeness they imply. Moreover, we study whether they still characterize a valued total interval
orders. 相似文献
75.
Bernard L. G. Bakker 《Few-Body Systems》2011,49(1-4):177-181
Calculations in light-front quantization are sometimes found to lead to singularities that are not present in the corresponding manifestly covariant treatment. We give some examples that were found in the framework of perturbation theory, but must also occur in nonperturbative calculations. In the case of anomalies, regularization-scheme dependences were found that not only occur between the light-front approach and manifestly covariant calculations, but also among the latter ones. 相似文献
76.
Avik Khan Khanh Dang Vu Gregory Chauve Jean Bouchard Bernard Riedl Monique Lacroix 《Cellulose (London, England)》2014,21(5):3457-3468
Microfluidization, which is a high-pressure homogenization technique, was used to develop highly dispersed cellulose nanocrystal (CNC) reinforced chitosan based nanocomposite films. A three factor central composite design with five levels was designed to systematically optimize the microfluidization process. The three factors were the CNC content, the microfluidization pressure and the number of microfluidization cycles. Response surface methodology was used to obtain relationship between the mechanical properties of the nanocomposite films and the factors. Polynomial equations were generated based on the regression analysis of the factors and the predicted properties of the nanocomposite films were in good agreement with the experimental results. Microfluidization effectively reduced the CNC–chitosan aggregates and improved the mechanical properties of the nanocomposite films. Microscopic analysis of the microfluidized nanocomposite films revealed a 10–15 times reduction in the size of the aggregates compared to the non-microfluidized CNC/chitosan films and an increase in the root mean square surface roughness (Rq). 相似文献
77.
Bojan Šarac Janez Cerkovnik Bernard Ancian Guillaume Mériguet Gaëlle M. Roger Serge Durand-Vidal Marija Bešter-Rogač 《Colloid and polymer science》2011,289(14):1597-1607
The complex aggregation processes of dodecyltrimethylammonium chloride (DTAC) have been studied in dilute solutions of sodium
salicylate (NaSal) by isothermal titration calorimetry and electrical conductivity at temperatures between 278.15 K and 318.15 K.
A structural transformation that was dependent on the concentrations of DTAC and NaSal was observed. The micellization process
in dilute solutions of DTAC has been subjected to a detailed thermodynamic analysis and shown to occur at considerably lower
critical micelle concentrations than reported for DTAC in water and NaCl solutions. Gibbs free energy, Δ
mic
G
o, and entropy, Δ
mic
S
o, were deduced by taking into account the degree of micelle ionization, β, estimated from conductivity measurements. From the temperature dependence of the enthalpy of micellization, Δ
mic
H
o, the heat capacities of micellization, Dmic cpo {\Delta_{{{\rm mic} }}}c_p^o were determined and discussed in terms of the removal of large areas of non-polar surface from contact with water upon micellization.
The process is exothermic at all temperatures, indicating, in addition to the hydrophobic effect, the presence of strong interactions
between surfactant and salicylate ions. These were confirmed by 1H NMR spectroscopy and diffusion NMR experiments. Salicylate ions not only interact with the headgroups but also insert further
into the micelle core. At c
NaSal/c
DTAC > 2.5, the structural rearrangements occur even at relatively low concentrations of NaSal. 相似文献
78.
Tingting Yan Dr. Binglei Song Dr. Xiaomei Pei Prof. Zhenggang Cui Prof. Bernard P. Binks Dr. Hengquan Yang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(2):647-651
A surfactant, R-6-AO, derived from dehydroabietic acid has been synthesized. It behaves as a highly efficient low-molecular-weight hydrogelator with an extremely low critical gelation concentration (CGC) of 0.18 wt % (4 mm ). R-6-AO not only stabilizes oil-in-water (O/W) emulsions at concentrations above its critical micelle concentration (cmc) of 0.6 mm , but also forms gel emulsions at concentrations beyond the CGC with the oil volume fraction freely adjustable between 2 % and 95 %. Cryo-TEM images reveal that R-6-AO molecules self-assemble into left-handed helical fibers with cross-sectional diameters of about 10 nm in pure water, which can be turned to very stable hydrogels at concentrations above the CGC. The gel emulsions stabilized by R-6-AO can be prepared with different oils (n-dodecane, n-decane, n-octane, soybean oil, olive oil, tricaprylin) owing to the tricyclic diterpene hydrophobic structure in their molecules that enables them to adopt a unique arrangement in the fibers. 相似文献
79.
Basener W Brooks B Radin M Wiandt T 《Nonlinear dynamics, psychology, and life sciences》2008,12(1):29-53
We analyze a discrete version of a recently developed ratio dependent population-resource model. This model has been used to study the decline of the human and resource populations on Easter Island and the chaotic dynamics of moose and wolf populations in Canada. The dynamical system exhibits a rich behavior of fractal basins of attraction and a Neimark-Sacker bifurcation route to chaos. The model consists of a coupled pair of logistic equations, with the carrying capacity for the predators proportional to the number of prey. 相似文献
80.
Les Sels de Bismuth (III) Comme Catalyseurs Dans la Reaction D'ouverture Des Epoxydes Par Les Amines
Adyl Oussaid Bernard Garrigues Boualem Oussaid Fatima Benyaquad 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2315-2320
BiCl 3 and Bi (OTf) 3 catalyze the opening of epoxides ( 1-7 ) by amines ( 8-12 ). High regioselectivities are observed. BiCl 3 et Bi (OTf) 3 catalysent la réaction d'ouverture des époxydes ( 1-7 ) par les amines ( 8-12 ). La réaction est fortement régiosélective. 相似文献