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排序方式: 共有103条查询结果,搜索用时 31 毫秒
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2.
Aycha Jellali Slim Elleuch Besma Hamdi Ridha Zouari 《Journal of Saudi Chemical Society》2019,23(5):600-611
In this work, a new hybrid material (C5H6N2Cl)2[FeCl4].Cl abbreviated (CAP)2[FeCl4].Cl was prepared using room temperature slow evaporation technique. The X-ray diffraction analysis revealed that the compound is crystallized in the centrosymmetric space group P21/c of the monoclinic system. The crystallographic network consists of an Fe(III) ion located on an inversion center and coordinated by four chlorine, isolated Cl– and two (CAP)+ protonated cations linked by N–H...Cl and C–H...Cl hydrogen bonds to form a zero-dimensional network. Hirshfeld surface analysis was used to analyze intermolecular interactions present in the crystal structure. The vibrational properties were inspected by means of Infra-Red absorption and Raman diffusion spectroscopy techniques. In addition, theoretical calculations based on the DFT/B3LYP/LanL2DZ method and the time-dependent density functional theory (TD–DFT) were performed in order to gain more information and help in the examination of over-all properties of the title compound. Good and interesting experimental findings were presented and good consistency was found with the calculated results. 相似文献
3.
Barbu Vlad Stefan Beltaief Slim Pergamenshchikov Sergey 《Statistical Inference for Stochastic Processes》2019,22(2):187-231
Statistical Inference for Stochastic Processes - We consider the nonparametric robust estimation problem for regression models in continuous time with semi-Markov noises. An adaptive model... 相似文献
4.
Comparison of multicomponent fuel droplet vaporization experiments in forced convection with the Sirignano model 总被引:2,自引:0,他引:2
A. Daï f M. Bouaziz X. Chesneau A. Ali Ch rif 《Experimental Thermal and Fluid Science》1998,18(4):282-290
The vaporization of multicomponent fuel droplets was studied experimentally in a heated flow and the results were compared to the model proposed by Abramzon and Sirignano. The droplet was suspended on a permanent holder which was set up in a thermal wind-tunnel. This wind-tunnel was fitted with a video recording system and an infra-red camera. The period during which the droplet was suspended on the holder before the opening of the hot air flow damper was recorded. This first sequence corresponds to the droplet vaporization in natural convection, whose initial experiment conditions, especially diameter, temperature, composition of the droplet, are well known. Then the damper was turn on, and the sequence of forced convection begun. The initial diameter of the droplet was recorded by the video system. The other initial conditions of this second sequence cannot be determined experimentally. The distribution of temperature in the droplet and the surface temperature, the mass fraction distribution in the droplet and the surface mass fraction were unknown. These unknown parameters were determined by coupling our experiment with a model using “the film concept” in natural convection. Experimental results were compared with the calculations and found satisfactory, in natural convection as well as in forced convection initiated by this method. The method was tested in the case of a fuel mixture droplets (heptane–decane) for different initial concentrations and variable durations of the sequence in natural convection. 相似文献
5.
Nesrine Mechi Ismahen Ben Khemis Houcine Dhaou Slim Zghal Abdelmottaleb Ben Lamine 《Chinese Journal of Physics (Taipei)》2018,56(2):449-467
The Mg50Ni45Cr5 alloy for hydrogen storage is prepared by mechanical alloying. First, using the X-ray diffraction (XRD) and the scanning electron microscopy (SEM) we examine the morphology and the structure of the substrate. The obtained results highlight the effectiveness of this alloy in loading hydrogen as it is a nanocrystalline and a ductile one. Second, we attempt to justify these expectations using the statistical physic, precisely the model monolayer with two levels of energy, in modeling a hydrogen absorption and desorption isotherms on Mg50Ni45Cr5 alloy at four temperatures T?=?275?K, T?=?300?K, T?=?325?K and T?=?350?K. The model has six physicochemical parameters deduced from the fitting of the isotherms, they are divided by two categories of steric and energetic parameters. Thanks to these parameters we compare the absorption and desorption processes, in order to highlight the hysteresis phenomenon encountered during the hydrogen sorption. 相似文献
6.
Zouhaier Bouallagui Mohamed Bouaziz Salwa Lassoued Jean Marc Engasser Mohamed Ghoul Sami Sayadi 《Applied biochemistry and biotechnology》2011,163(5):592-599
We previously reported the production of high yields of hydroxytyrosol through the bioconversion of tyrosol. In the present
work, hydroxytyrosol was subjected to the lipase catalyzed acylation aiming for the recovery of more lipophilic esters that
might be easily incorporated in cosmetic and food preparations. Hydroxytyrosyl acetate and hydroxytyrosyl oleate were produced
with respective molar esterification yields of 98% and 78%. DPPH free radical quenching potency demonstrated that the acylation
of hydroxytyrosol did not alter its antioxidant activity. The acylated esters were shown to be more effective than the natural
antioxidant: caffeic acid and two synthetic ones as BHA and BHT. Antiproliferative activity on human cervical cells (HeLa)
resulted in IC50 values of 0.46, 0.42 and 0.33 mM for hydroxytyrosol and its acetyl and oleyl esters, respectively. Additionally, when used
at a non-cytotoxic concentration (100 μM), these compounds showed significant effectiveness in preventing iron-induced oxidative
stress, resulting in a reduction of 30%, 36% and 38% in thiobarbituric acid-reactive substance production, respectively. 相似文献
7.
We show that the heat semigroup is well defined on the Banach space \({\mathcal{X}_{m,\gamma} = \{ \psi:\Omega_m \to \mathbb{R} ;\; |x|^{\gamma +2m}(\prod_{i=1}^m x_i)^{-1}\psi(x) \in L^\infty(\Omega_m)\},}\) \({0 < \gamma < N}\), where \({\Omega_m=\{(x_1,\, x_2,\, \ldots,\, x_N) \in \mathbb{R}^{N};\; x_i > 0,\, 1\leq i\leq m\},}\) \({1\leq m\leq N}\). We then investigate the large time behavior of solutions of the heat equation \({u_{t}-\Delta u=0}\) for t > 0 and \({x \in \Omega_m.}\) Using certain notions from dynamical systems, we show that the large time behavior is related to the spatial asymptotic behavior of its initial value. Since the space \({\mathcal{X}_{m, \gamma}}\) contains highly singular initial data, which can be extended to all of \({\mathbb{R}^{N}}\) by antisymmetry, we also obtain new results on the complexity in the asymptotic behavior of solutions for the heat equation on the whole space. 相似文献
8.
We consider the general nonlinear heat equation on where and g satisfies certain growth conditions. We prove the existence of global solutions for small initial data with respect to a
norm which is related to the structure of the equation. We also prove that some of those global solutions are asymptotic for
large time to self-similar solutions of the single power nonlinear heat equation, i.e. with
Received: 23 July 1999 / Accepted: 14 December 2000 / Published online: 23 July 2001 相似文献
9.
In this paper we are studying a robotic assembly line balancing problem. The goal is to maximize the efficiency of the line and to balance the different tasks between the robots by defining the suitable tasks and components to assign to each robot. We are interested in a robotic line which consists of seizing the products on a moving conveyor and placing them on different location points. The performances evaluations of the system are done using a discret event simulation model. This latter has been developed with C++ language. As in our industrial application we are bounded by the execution time, we propose some resolution methods which define the suitable component and point positions in order to define the strategy of pick and place for each robot. These methods are based on the ant colony optimization, particle swarm optimization and genetic algorithms. To enhance the quality of the developed algorithms and to avoid local optima, we have coupled these algorithms with guided local search. After that, an exact method based on full enumeration is also developed to assess the quality of the developed methods. Then, we try to select the best algorithm which is able to get the best solutions with a small execution time. This is the main advantage of our methods compared to exact methods. This fact represents a great interest taking in consideration that the selected methods are used to manage the functioning of real industrial robotic assembly lines. Numerical results show that the selected algorithm performs optimally for the tested instances in a reasonable computation time and satisfies the industrial constraint. 相似文献
10.
Abderrazak Bouaziz 《Inventiones Mathematicae》1994,115(1):163-207
Sans résuméOblatum 28-I-1992 & 13-VII-1992 相似文献