排序方式: 共有14条查询结果,搜索用时 15 毫秒
1.
In this paper, we introduce for the first time a new eligible kernel function with a hyperbolic barrier term for semidefinite programming(SDP). This add a new type of functions to the class of eligible kernel functions. We prove that the interior-point algorithm based on the new kernel function meets O(n3/4 logε/n)iterations as the worst case complexity bound for the large-update method. This coincides with the complexity bound obtained by the first kernel function with a trigonometri... 相似文献
2.
This paper proposes a new approach for decision making under uncertainty based on influence diagrams and possibility theory. The so-called qualitative possibilistic influence diagrams extend standard influence diagrams in order to avoid difficulties attached to the specification of both probability distributions relative to chance nodes and utilities relative to value nodes. In fact, generally, it is easier for experts to quantify dependencies between chance nodes qualitatively via possibility distributions and to provide a preferential relation between different consequences. In such a case, the possibility theory offers a suitable modeling framework. Different combinations of the quantification between chance and utility nodes offer several kinds of possibilistic influence diagrams. This paper focuses on qualitative ones and proposes an indirect evaluation method based on their transformation into possibilistic networks. The proposed approach is implemented via a possibilistic influence diagram toolbox (PIDT). 相似文献
3.
4.
Brahmi Khaled Bouguerra Wided Hamrouni Béchir Elaloui Elimame Loungou Mouna Tlili Zied 《Arabian Journal of Chemistry》2019,12(8):1848-1859
This study investigates the effect of reactor design parameters on cadmium removal from industrial wastewater discharged by the Tunisian Chemical Group (TCG) to improve as much as possible efficiency and cost of electrocoagulation (EC) process. Based on an examination of the design parameters one by one, the best cadmium removal was achieved for an inter-electrode distance (die) of 0.5 cm, monopolar connection mode, stirring speed of 300 rev min?1, surface-area-to-volume ratio (S/V) of 13.6 m?1, and an initial temperature of 50 °C. These operating conditions are allowed to achieve efficient removal in a relatively short operating time with the lowest energy consumption and cost possible. The present study proved that the parameters that have an effect on the operating cost are the electrode configuration, inter-electrode distance and S/V ratio. The energy consumption, the pH evolution, and the treatment cost were studied. The investigation of the effect of all the selected optimum EC design parameters together on the removal of cadmium from the TCG wastewater proved that the treatment was highly efficient; 100% of cadmium removal was reached in 5 min, with a very low power consumption (1.6 kW h m?3) and very low cost (0.116 TND m?3). Moreover, EC was found to be capable of removing cadmium as well as other pollutants at the same time from the case-study industrial wastewater. The investigation carried out in this work explores and proposes a very cost-effective treatment method to remove heavy metals from industrial wastewater if compared to results reported about cost of this treatment process through other widely used technologies such as coagulation (4.36 Tunisian National Dinar (TND) m?3) and precipitation (9.96 TND m?3) employed in previous studies. 相似文献
5.
A study is performed on polychlorinated biphenyl (PCB) congener residues in samples of human blood and milk as well as in falcon and pigeon eggs. Most of the PCB congeners found in these biological samples were quantified by high-resolution gas chromatography (HRGC). A PCB technical mixture--namely, DP6 (Phenochlor)--was used for the calibration as its composition was previously determined by HRGC-mass spectrometry. The usefulness of such a congener analysis is outlined. It is the first time to the best of our knowledge that a Phenochlor mixture is used for standardization. 相似文献
6.
Photo-oxidation process of indole in aqueous solution with ZnO Catalyst: Study and optimization 总被引:1,自引:0,他引:1
M. Samah S. Merabet M. Bouguerra M. Bouhelassa S. Ouhenia A. Bouzaza 《Kinetics and Catalysis》2011,52(1):34-39
The photo-oxidation of indole has been investigated using the catalytically active ZnO in aqueous solution, under various
physical and chemical conditions. First of all, a structural analysis with X ray diffraction (XRD) shows that ZnO powder crystallizes
in wurtzite with a main grain size estimated to be about 270 nm. An increase in catalyst loading greatly enhances the process
efficiency until a certain. limit. Indole photodegradation improves with increasing air flow. The effect of the pH on the
photo-oxidation efficiency was carried out from 3.88 to 11.16. The activity exhibits its maximal value around the natural
pH (6.68). Photocatalytic degradation showed that the activity of ZnO improved with increasing light intensity. This was ascribed
to the fact that there was a more efficient generation of electron-hole pairs used in the degradation process. 相似文献
7.
Y. Bouguerra M. Maamache A. Bounames 《International Journal of Theoretical Physics》2006,45(9):1791-1797
We use the Lewis-Riesenfeld theory to determine the exact form of the wavefunctions of a two-dimensionnal harmonic oscillator with time-dependent mass and frequency in presence of the Aharonov-Bohm effect (AB). We find that the auxiliary equation is independent of the AB magnetic flux. In the particular case of quantized AB magnetic flux the wavefunctions coincide exactly with the wavefunctions of the 2D time-dependent harmonic oscillator.
PACS: 03.65Ge; 03.65Fd; 03.65Bz 相似文献
8.
Lair V Bouguerra S Turmine M Letellier P 《Langmuir : the ACS journal of surfaces and colloids》2004,20(20):8490-8495
Dodecyldimethylamine N-oxide (DDAO) is a zwitterionic surfactant with acid-base properties. The proton dissociation constant of this surfactant was determined by a novel potentiometric method at "controlled chemical potential" of the proton using a classical pH-glass electrode. When the DDAO was in its monomeric form, the pKa was about 5, consistent with the value commonly reported in the literature. However, a unique proton dissociation constant specific to the micellar form of this surfactant could not be obtained. We found that the acid-base behavior of the DDAO micelles depended on their environment. Indeed, we were able to establish thermodynamic relations linking the critical micellar concentration to the degree of protonation of the micelles. The experimental values were in good accordance with this model. 相似文献
9.
Rania Ben Hmida Nourzed Frikha Soumaya Bouguerra Neji Geoffrey Kit Francisco Medina Mohamed Bouaziz 《国际化学动力学杂志》2020,52(2):124-133
An effective procedure was developed to produce high-value added phenolic compounds through the conversion of 2-phenylethanol (2-PhEt) by using acid-activated clays KSF for the hydrogen peroxide. Owing to KSF's ability to catalyze a variety of complex oxidations, it was likely to convert 2-PhEt to hydroxytyrosol (HTY) and tyrosol (TY) derivatives. The analyses of catalytic solution revealed that the optimum conditions, giving a higher concentration of oxidation products such as HTY, were as follows: 2-PhEt concentration 10−2 mol/L, the hydrogen peroxide concentration 5.05 × 10−2 and 0.6 g L–1 of KSF clays . The yield during the conversion reaction into HTY was around 25%. All compounds in the reaction mixture were identified by mass spectrophotometry using a LC-MS apparatus. HTY, TY, meta-tyrosol and ortho-tyrosol were the major compounds. The antioxidant activity was realized by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. In fact, it is revealed that the strongest inhibition percentage (PI = 96) was detected with the increase in the concentration of HTY. The approach proposed in the present work presents an environment friendly method. 相似文献
10.
Wided Mejri Ilhem Ben Salah Mohamed Mouldi Tlili 《Crystal Research and Technology》2015,50(3):236-243
The present work was carried out to investigate separately the effect of Fe2+ and Fe3+ on the precipitation kinetics and the microstructure of CaCO3. For this an experimental procedure was proposed. Precipitation tests were made by using the dissolved‐CO2 degassing method. Both air and nitrogen were employed to strip the CO2 from a Ca(HCO3)2 solution initially rich in this gas. At anoxic medium, it was shown that iron (II) prolongs the nucleation step and decelerates the crystalline growth rate. X‐ray diffraction analysis shows that its presence inhibits calcite and promotes aragonite variety. By using air, the reaction medium is rich in oxygen and iron (II) is rapidly oxidized. Seeing the higher solution pH (> 6.5), iron hydroxide forms before the onset of CaCO3 precipitation and plays a role of seed permitting to initiate CaCO3 nucleation. So, contrary to the observed effect of iron (II), the presence of iron (III) accelerates the precipitation rate of CaCO3. As for iron (II), iron (III) inhibits calcite formation but favored the vaterite variety instead of the aragonite one. 相似文献