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51.
The development of mathematical models for the design of controlstrategies for spark ignition automotive engines is described. The objectiveof the models, used for both simulation and optimization analysis, is theprediction of the effects of control strategies on fuel consumption andemissions of a vehicle over arbitrary driving cycles. In order to achievethe best compromise between precision, experimental costs, computationaltime and flexibility, a mixed modelling approach is used, withphenomenological and input-output models integrated within a hierarchicalsystem.Mean value models have been used to describe the most significant dynamiceffects: (i) air flow. (ii) two phases fuel flow in the intake manifold, and(iii) thermal flow in the cylinder walls. Stochastic effects due to sensorsand actuators can be also predicted.Two-zone and multizone thermodynamic models for the prediction ofpressure cycle sub-models for engine emissions (HC, CO, andNO
x
and mechanical losses have been developed. Experimentaldesign techniques are also under development to optimize the interactionsbetween experimental analysis and models. Most of the models have beenintegrated in a computer code, used by a major automotive supplier. 相似文献
52.
Giuseppe Cirillo Francesco Puoci Manuela Curcio Ortensia Ilaria Parisi Francesca Iemma Umile Gianfranco Spizzirri Nevio Picci 《Colloid and polymer science》2010,288(6):689-693
The aim of this study is the preparation of molecularly imprinted polymers by employing a redox pair as initiator system.
Bulk molecularly imprinted polymers were synthesized by using Fenton reagents as initiator system. Theophylline, methacrylic
acid, and ethylene glycol dimethacrylate were employed as model template, functional monomer, and crosslinking agent, respectively.
Conventional imprinted polymers were also prepared by using 2,2′-azoisobutyronitrile in order to evaluate the efficiency of
the proposed initiator system. Redox molecularly imprinted polymers and conventional molecularly imprinted polymers were characterized
by water uptake measurement, while the imprinting effect of synthesized polymers were evaluated by performing binding experiments
in organic (acetonitrile) and in water (buffered water solution at pH = 7.4) media. 相似文献
53.
Luca Schiaffino Dr. Gianfranco Ercolani Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(10):3147-3156
The mechanism of the Soai reaction has been thoroughly investigated at the M05‐2X/6‐31G(d) level of theory, by considering ten energetically distinct paths. The study indicates the fully enantioselective catalytic cycle of the homochiral dimers to be the dominant mechanism. Two other catalytic cycles are shown to both be important for correct understanding of the Soai reaction. These are the catalytic cycle of the heterochiral dimer and the non‐enantioselective catalytic cycle of the homochiral dimers. The former has been proved to be not really competitive with the principal cycle, as required for the Soai reaction to manifest chiral amplification, whereas the latter, which is only slightly competitive with the principal one, nicely explains the experimental enantioselectivity observed in the reaction of 2‐methylpyrimidine‐5‐carbaldehyde. The study has also evidenced the inadequacy of the B3LYP functional for mechanistic investigations of the Soai reaction. 相似文献
54.
55.
Francesco Napoli Dr. Mario Chiesa Dr. Elio Giamello Prof. Gloria Preda Dr. Cristiana Di Valentin Dr. Gianfranco Pacchioni Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(23):6776-6785
The formation of O2? radical anions by contact of O2 molecules with a Na pre‐covered MgO surface is studied by a combined EPR and quantum chemical approach. Na atoms deposited on polycrystalline MgO samples are brought into contact with O2. The typical EPR signal of isolated Na atoms disappears when the reaction with O2 takes place and new paramagnetic species are observed, which are attributed to different surface‐stabilised O2? radicals. Hyperfine sublevel correlation (HYSCORE) spectroscopy allows the superhyperfine interaction tensor of O2?Na+ species to be determined, demonstrating the direct coordination of the O2? adsorbate to surface Na+ cations. DFT calculations enable the structural details of the formed species to be determined. Matrix‐isolated alkali superoxides are used as a standard to enable comparison of the formed species, revealing important and unexpected contributions of the MgO matrix in determining the electronic structure of the surface‐stabilised Na+? O2? complexes. 相似文献
56.
Indirect control of corporations 总被引:4,自引:0,他引:4
We consider situations in which shares ofn firms are held by the samen firms as well as by individual investors. The probelm is to determine the actual control of the firms by the individual investors.In part 1, we develop the mathematical model, and explain the basic notions of clutter and of effective reduction. In part 2 we introduce the idea of a consistent reduction, prove existence of such, and show the relation between consistent and effective reductions. In part 3 we introduce multilinear extensions and show how these can be used to calculate the effective and consistent reductions. Several examples are worked out in detail. 相似文献
57.
A rigorous wave-theoretic approach to the Michelson-Morley (M-M) experiment is presented, with special emphasis on the Huygens' principle derivation of the laws of reflection by a moving mirror. A detailed discussion of the Lorentz-Fitzgerald contraction hypothesis (CH) is included. Several mistakes appearing in the standard textbook treatments of these issues are pointed out, and a number of related historical questions are considered. 相似文献
58.
Martina Mazzoni Lorenzo Franco Alberta Ferrarini Carlo Corvaja Giovanni Zordan Gianfranco Scorrano Michele Maggini 《Liquid crystals》2002,29(2):203-208
A nitroxide [60]fullerene adduct containing a pyrrolidine-1-oxyl group has been synthesized. Its orientational order in the nematic phase of the liquid crystal solvent 4,4'-azoxyanisole (PAA) has been measured from the variation of the EPR spectral parameters on passing from the isotropic to the nematic phase. Highly resolved EPR lines allow for precise evaluation of the shifts of the g , a N and a H values. Since the g and the hyperfine tensors are known, the order matrix could be obtained. This is compared with the one calculated with a theoretical model based on short range solute-solvent interactions, which predicts a considerable degree of orientation of the molecular axes, despite the almost spherical shape of the molecule. The agreement with experimental findings is quite good and it is further improved if a bent structure of the pyrrolidine ring is taken into account. 相似文献
59.
60.
Gianfranco Capriz 《Meccanica》1967,2(4):213-217
Summary To obtain an accurate forecast of the behaviour of a shaft rotating on lubricated bearings under excitation, an adequate model must be introduced to represent the response of the bearings; a linear model of the response is sufficient for many practical purposes, but allowance must be made for the variation of film stiffness, cross-stiffness, etc., with direction. As a consequence the shaft must be assumed to move in an elliptical, rather than circular, whirl. The phenomenon which must be analyzed is thus more complex than that envisaged in König's study, for instance, see Ref. [2]. We show here nevertheless that it is possible to devise an appropriate generalization of the Myklestad-Holzer method, so that the problem can be solved by matrix manipulations.
Sommario Per prevedere con accuratezza l'ampiezza di vibrazione di un asse lievemente sbilanciato che ruoti su supporti lubrificati è necessario rappresentare adeguatamente il comportamento dei supporti stessi.Un modello lineare è sufficiente per molti scopi pratici purchè si tenga conto che la risposta non ha generalmente simmetria assiale. Di conseguenza è necessario poter considerare casi nei quali la traiettoria di ciascun punto dell'asse è ellittica piuttosto che circolare. Perciò si richiede una generalizzazione del metodo di König; generalizzazione che è indicata nel presente lavoro. Il metodo proposto fa però ancora uso di semplici operazioni matriciali.相似文献