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11.
The problem of arbitrarily incident plane-wave scattering from rod structures of thick conducting plates arranged with two-dimensional (2D) periodicity has been examined. The square approximation as well as truncated-square approximation of circular cross sections is used in this study. The impedance of cascaded screens and the reflection coefficient is calculated using the multimodal variational method for both TE- and TM-polarized incident electric field. The 2D periodic structure of holes described in this paper can be used for the purpose of designing new guiding microwave structures. A transverse resonance method is applied to solve this problem. The convergence behavior of the technique has also been examined. The numerical results of the reflection coefficient, surface impedance, and dispersion curves are presented 相似文献
12.
13.
Knowledge representation issues related to the modelling of imprecision and uncertainty are discussed in the framework of possibility theory. Differences and relations between possibility theory, fuzzy sets, probability theory and Shafer evidence theory are presented. Then, patterns of reasoning and inference and control procedures are studied in presence of uncertainty and imprecision using a possibilistic approach. the basic ideas and the main trends are emphasized rather than the mathematical and logical foundations or the technical details of implementation which can be found in the references. 相似文献
14.
Michel Dorbon Pierre Henri Bigeard Jacques Denis Christian Bernasconi 《Petroleum Science and Technology》1992,10(8):1313-1341
As established by several previous works, nitrogen compounds play a prominent role in the evolution of middle distillates containing cracked components, particularly regarding sediment formation and color evolution.
In a first part, this paper describes and compares stability properties of fuel blends using both an accelerated ageing method at 120°C (248°F ) and long term storage methods at 43°C(110°F) -ASTM 0 4625 - and at ambient temperature. Effectiveness of stabilizing additives is also evaluated. In mixtures containing LCOs, insoluble products are formed progressively during ageings, more or less rapidly according to the chemical constitution of the mixtures.
Then, it reports the complete identification of nitrogen compounds using gas chromatography equipped with a selective nitrogen detector and mass spectrometry showing that in light cycle oils, alkyl indoles and carbazoles are the main families.
Evolution of these compounds was followed kinetically during ageings in absence and presence of additives and alkyl indoles appeared as the moat evolutionary.
It appeared that some additives avoided evolutions of alkyl indoles without preventing sediment formation and color evolution. Oxidation mechanism involving nitrogen compounds should not be the only one to explain the storage evolutions of middle distillates.
Hydrotreatment converts all the alkyl indoles of LCO and prevents coloration end deposits in the storage of the mixtures of steaight-run distillates and LCOs. 相似文献
In a first part, this paper describes and compares stability properties of fuel blends using both an accelerated ageing method at 120°C (248°F ) and long term storage methods at 43°C(110°F) -ASTM 0 4625 - and at ambient temperature. Effectiveness of stabilizing additives is also evaluated. In mixtures containing LCOs, insoluble products are formed progressively during ageings, more or less rapidly according to the chemical constitution of the mixtures.
Then, it reports the complete identification of nitrogen compounds using gas chromatography equipped with a selective nitrogen detector and mass spectrometry showing that in light cycle oils, alkyl indoles and carbazoles are the main families.
Evolution of these compounds was followed kinetically during ageings in absence and presence of additives and alkyl indoles appeared as the moat evolutionary.
It appeared that some additives avoided evolutions of alkyl indoles without preventing sediment formation and color evolution. Oxidation mechanism involving nitrogen compounds should not be the only one to explain the storage evolutions of middle distillates.
Hydrotreatment converts all the alkyl indoles of LCO and prevents coloration end deposits in the storage of the mixtures of steaight-run distillates and LCOs. 相似文献
15.
Nadia Ben Atti Gema M. Diaz–Toca Henri Lombardi 《Applicable Algebra in Engineering, Communication and Computing》2006,17(1):75-82
We propose a slight modification of the Berlekamp-Massey Algorithm for obtaining the minimal polynomial of a given linearly
recurrent sequence. Such a modification enables to explain it in a simpler way and to adapt it to lazy evaluation.
partially supported by the Galois Theory and Explicit Methods in Arithmetic Project HPRN-CT-2000-00114
partially supported by the European Union funded project RAAG CT-2001-00271 相似文献
16.
Henri Prade 《Journal of Intelligent and Robotic Systems》1990,3(2):93-101
In this note, we are interested in the evaluation of conditions of the form The value of attribute a for Q items of X is in F or more shortly Q items of X are F, where X is a set of items, Q denotes a possibly vague proportion (which may be linguistically expressed, e.g. most), F is a (possibly fuzzy) subset of the attribute domain of a. and where the available knowledge about the value a(x) of the attribute a for any item x may be imprecise or even vague. The evaluation is based on a fuzzy pattern matching procedure repeated two times. Such conditions may be encountered in queries addressed to an incomplete information data base or in the if-part of expert rules. 相似文献
17.
Fouad Laoutid Henri Vahabi Elnaz Movahedifar Pascal Laheurte Christelle Vagner Marianne Cochez Loïc Brison Mohammad Reza Saeb 《乙烯基与添加剂工艺杂志》2021,27(2):264-274
In this study, the effect of the chemical nature of different calcium (Ca)-based minerals as flame retardant additives in combination with ammonium polyphosphate (APP), in 1:1 proportions, on the flame retardancy behavior and performance of ethylene vinyl acetate copolymer was discussed. Combining APP with partly and completely hydrated calcium oxide led to superior flame-retardant function detected in mass loss calorimeter measurements with respect to the corresponding system containing carbonated calcium. This privileged character was attributed to the higher reactivity of hydrated Ca-based fillers toward APP in comparison with Ca carbonate, which induced the formation of an intumescent residue. The difference between reactivity potential of hydrated and dry Ca was demonstrated by the newly formed thermally stable species, and further evidenced by thermogravimetric analysis performed on APP/fillers blends. Moreover, the presence of more crystalline domains in the Ca/phosphorus-based compounds was evidenced by XRD analysis of the mass loss calorimeter test residues. The results of this work highlight the role of blend additive systems on the performance of flame retardancy of polymer materials. 相似文献
18.
Sara Cavaliere-Jaricot Arnaud Etcheberry Michel Herlem Henri Perez 《Electrochimica acta》2007,52(6):2285-2293
Platinum nanoparticles (n-Pt), over-grafted with 2-thiophenecarbonyl chloride are assembled on gold electrodes, by the Langmuir Blodgett (LB) technique using behenic acid (BHA) as promoting agent. These layers are electrochemically active without any preliminary activation. The [Fe(CN)6]3−/4− redox couple was used as electrochemical probe. This paper reports on the influence of the number of deposited LB layers, and the n-Pt density on the electrochemical response. n-Pt density was modified by the change of the “BHA/n-Pt” ratio. Cyclic voltammograms of “[Fe(CN)6]3−/4−” were observed whatever the coating conditions. As soon as the first layer was deposited the electrochemical response was associated to the n-Pt coverage, its response slightly increased up to a steady state for five or seven layers. As expected, the increase of the Pt density favored the increase of the current density. XPS analysis performed before and after electrochemical cycling showed that 4-mercaptoaniline capped platinum nanoparticles, and their over grafting were chemically and electrochemically stable. Analysis of influence of the number or the n-Pt density of the layers showed that the electrochemically active part of LB electrodes was provided by the last layer plus a part of the underlying one. 相似文献
19.
Copolymerization of norbornene with norbornene terminated polystyrene macromonomer in the presence of Ni-based/MAO catalytic systems 总被引:1,自引:0,他引:1
Copolymerization of -norbornenyl polystyrene macromonomer (NBE-PS) with norbornene (NBE) using Ni-based catalysts in combination with methylaluminoxane (MAO) was investigated. The nature of the catalyst, the
of the polystyrene macromonomer as well as the [NBE-PS]/[NBE] ratio have been shown to be important parameters to obtain graft copolymers with high NBE-PS incorporation (up to 43 wt%). The compatibilization ability of these graft copolymers has been checked for PS/PNBE blends. The length of the grafts was proved not to be an important parameter to consider compatibilization of the PS/PNBE blend. 相似文献
20.
The reactions of trans-2,5-dimethoxy-4′-aminostilbene with poly(maleic anhydride-co-methylvinyl ether) and trans-2,5-dimethoxy-4′-isocyanatostilbene with poly(oxy-1,4-phenyleneisopropylidene:1,4-phenyleneoxy-2-hydroxytrimethylene) yield polymeric systems which undergo rapid crosslinking upon short exposure to ultraviolet light. The extent of photocrosslinking as a function of exposure time was determined by the decrease of the trans-stilbene ultraviolet absorption at 350 nm. 相似文献