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41.
We present pseudo-potential calculations of geometrical structures of stable isomers of LiAr
n
clusters with both an electronic ground state and excited states of the lithium atom. The Li atom is perturbed by argon atoms
in LiAr
n
clusters. Its electronic structure obtained as the eigenfunctions of a single-electron operator describing the electron in
the field of a Li+Ar
n
core, the Li+ and Ar atoms are replaced by pseudo-potentials. These pseudo-potentials include core-polarization operators to account for
the polarization and correlation of the inert core with the valence Lithium electron [J Chem Phys 116, 1839 1]. The geometry optimization of the ground and excited states of LiAr
n
(n = 1–12) clusters is carried out via the Basin-Hopping method of Wales et al. [J Phys Chem 101, 5111 2; J Chem Phys 285, 1368 3]. The geometries of the ground and ionic states of LiAr
n
clusters were used to determine the energy of the high excited states of the neutral LiAr
n
clusters. The variation of the excited state energies of LiAr
n
clusters as a function of the number of argon atoms shows an approximate Rydberg character, corresponding to the picture
of an excited electron surrounding an ionic cluster core, is already reached for the 3s state. The result of optical transitions calculations shows that the absorption spectral features are sensitive to isomer
structure. It is clearly the case for transitions close to the 2p levels of Li which are distorted by the cluster environment. 相似文献
42.
Mounir Laroussi William T. Anderson 《Journal of Infrared, Millimeter and Terahertz Waves》1998,19(3):453-464
Plasma layers at atmospheric pressure, are good broad band absorbers of electromagnetic radiation. However, to get substantial attenuations, two parameters have to be optimized. These are the plasma number density, and the thickness of the plasma layer. It is found that in order to be an effective attenuator of microwave radiation, a plasma layer has to have a number density in the 1013 cm?3 range, and a thickness equal or larger than the wavelength of the incident wave. However, as the frequency increases, the amount of attenuation tends to reach a limiting value directly proportional to the number density. 相似文献
43.
Fatimetou mint El Mounir 《Positivity》2007,11(3):485-495
We give here some characterizations for normality and nuclearity of convex cones. We obtain a sufficient condition for weakly
normal cone to be normal (respectively nuclear).
Work partially supported by FNARS, Project 003. 相似文献
44.
We construct a dual semigroup of kernels associated to a semidynamical system. The above semigroup is in duality with the deterministic semigroup defined by Koopmann. We also prove the existence of right dual process associated to a semidynamical system. 相似文献
45.
Mounir Laroussi 《Journal of Infrared, Millimeter and Terahertz Waves》1996,17(12):2215-2232
In this paper, the total scattering and back-scattering cross-sections (respectively represented by σ and σb) of an air plasma layer surrounding a conducting cylinder are studied. The plasma layer can be turned ON and OFF to allow for a comparison between the scattering cross-section of the bare cylinder and the plasma covered cylinder. The plasma layer is generated at atmospheric pressure, which results in a very highly collisional case. The scattered fields are calculated using a cylindrical expansion, with coefficients satisfying the appropriate boundary conditions, and which are a function of the refractive index of the air plasma. The results of our study are presented as plots of the total scattering cross-section, σ, and back-scattering cross-section, σb, versus frequency. The scattering cross-section gives an average characteristic of the scattering process from obstacles. Once the scattering cross-section is known, the actual scattered energy per unit length per second can be calculated by multiplying σ by the incident energy per unit area per second. 相似文献
46.
Mounir Laroussi 《Journal of Infrared, Millimeter and Terahertz Waves》1995,16(12):2069-2083
In this paper, the interaction of microwaves with a plasma, generated at atmospheric pressure, is studied. The refractive index, attenuation index, skin depth, attenuation coefficient, phase coefficient, and reflectivity are investigated as functions of the plasma number density, the wave frequency and type of polarization, and the grazing angle. It is found that two frequency regimes characterize these type of plasmas. The first is a range where the phase velocity and attenuation of the wave both increase with frequency. The second is a frequency range in which the phase velocity and attenuation of the wave remain constant. It is also found that to have a shallow skin depth, the plasma number density has to be in the 1013 cm?3 range. The reflectivity is found to be an increasing function of the number density. In horizontal polarization, the reflectivity is a decreasing function of the grazing angle. But in vertical polarization and for grazing angle less than 20°, the reflectivity has a maximum at a frequency $f = f_s = \frac{{2\pi f_{pe}^2 }}{\nu }$ , where fpe is the electron plasma frequency and v is the collision frequency. 相似文献
47.
Guangwei He Shiqi Huang Luis Francisco Villalobos Mohammad Tohidi Vahdat Michael D. Guiver Jing Zhao Wan‐Chi Lee Mounir Mensi Kumar Varoon Agrawal 《Advanced functional materials》2020,30(39)
High‐flux nanoporous single‐layer graphene membranes are highly promising for energy‐efficient gas separation. Herein, in the context of carbon capture, a remarkable enhancement in the CO2 selectivity is demonstrated by uniquely masking nanoporous single‐layer graphene with polymer with intrinsic microporosity (PIM‐1). In the process, a major bottleneck of the state‐of‐the‐art pore‐incorporation techniques in graphene has been overcome, where in addition to the molecular sieving nanopores, larger nonselective nanopores are also incorporated, which so far, has restricted the realization of CO2‐sieving from graphene membranes. Overall, much higher CO2/N2 selectivity (33) is achieved from the composite film than that from the standalone nanoporous graphene (NG) (10) and the PIM‐1 membranes (15), crossing the selectivity target (20) for postcombustion carbon capture. The selectivity enhancement is explained by an analytical gas transport model for NG, which shows that the transport of the stronger‐adsorbing CO2 is dominated by the adsorbed phase transport pathway whereas the transport of N2 benefits significantly from the direct gas‐phase transport pathway. Further, slow positron annihilation Doppler broadening spectroscopy reveals that the interactions with graphene reduce the free volume of interfacial PIM‐1 chains which is expected to contribute to the selectivity. Overall, this approach brings graphene membrane a step closer to industrial deployment. 相似文献
48.
Sidi Ahmed Ezzahidi Essaid Sabir Mounir Ghogho 《International Journal of Communication Systems》2019,32(2)
We deal in this article with the content forwarding problem in delay tolerant networks (DTNs). We first formulate the content delivery interaction as a noncooperative satisfaction game. On one hand, the source node seeks to ensure a delivery probability above some given threshold. On the other hand, the relay nodes seek to maximize their own payoffs. The source node offers a reward (virtual coins) to the relay, which caches and forwards the file to the final destination. Each relay has to solve the dilemma of accepting/rejecting to cache the source's file. Cooperation incurs energy cost due to caching, carrying, and forwarding the source's file. Yet when a relay accepts to cooperate, it may receive some reward if it succeeds to be the first relay to forward the content to the destination. Otherwise, the relay may receive some penalty in the form of a constant regret; the latter parameter is introduced to make incentive for cooperation. Next, we introduce the concept of satisfaction equilibrium (SE) as a solution concept to the induced game. Now, the source node is solely interested in reaching a file delivery probability greater than some given threshold, while the relays behave rationally to maximize their respective payoffs. Full characterizations of the SEs for both pure and mixed strategies are derived. Furthermore, we propose two learning algorithms allowing the players (source/relays) to reach the SE strategies. Finally, extensive numerical investigations and some learning simulations are carried out to illustrate the behavior of the interacting nodes and to give some insightful thoughts on how to fine‐tune the network setting. 相似文献
49.
Salim Ben?Chaabane Mounir Sayadi Farhat Fnaiech Eric Brassart Franck Betin 《Circuits, Systems, and Signal Processing》2011,30(1):55-71
In this paper, the problem of colour image segmentation is addressed using the Dempster–Shafer (DS) theory. Examples are provided
showing that this theory is able to take into account a large variety of special situations that occur and which are not well
solved using classical approaches. Modelling both uncertainty and imprecision, and computing the conflict between images and
introducing a priori information are the main features of this theory. Consequently, the performance of such a segmentation
scheme is largely conditioned by the appropriate estimation of mass functions in the DS evidence theory. In this paper, a
new method of automatically determining the mass function for colour-image segmentation problems is presented. The mass function
of each pixel is determined by applying possibilistic c-means (PCM) clustering to the grey levels of the three primitive colours.
A reliability criterion, associated with each pixel and the mass functions of its neighbouring pixels, is used into a fuzzy
based reasoning system in order to decide on the appropriate segmentation. Experimental segmentation results on medical and
textured colour images highlight the effectiveness of the proposed method. 相似文献
50.
Let {SHt, t ≥ 0} be a linear combination of a Brownian motion and an independent sub-fractional Brownian motion with Hurst index 0 H 1. Its main properties are studied.They suggest that SHlies between the sub-fractional Brownian motion and the mixed fractional Brownian motion. We also determine the values of H for which SHis not a semi-martingale. 相似文献