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51.
A. Hachemi S. Mouhtamid D. Weichert 《Archive of Applied Mechanics (Ingenieur Archiv)》2005,74(11-12):762-772
This paper reports on recent developments in the field of direct methods, in particular shakedown analysis (SA) from theoretical and numerical points of view. Emphasis is placed on problems connected with the failure of fibre-reinforced periodic composites under variable loads where special attention is paid to the problem of interface debonding between fibre and matrix materials. The approach is based on a local SA in a representative volume element of the composite and the use of averaging techniques to study the influence of each component (matrix, fibre and interface) on the macroscopic response of such composite. For numerical applications, the interior-point difference-of-convex-functions algorithm (IPDCA) is proposed as an efficient method for solving large-scale problems. 相似文献
52.
Metal complexes as color indicators for the determination of acid-base properties of solid catalysts
The Lewis acid-basicity of a solid catalyst was determinated by using solution of Cu(tmen) (acac) (NO3) and Fe(phen)2 (CN)2 as Lewis acid-base indicators. 相似文献
53.
Mohamed Yacine Ameur Messaoud Ghenia Bentabed-Ababsa Ziad Fajloun Monzer Hamze Yury S. Halauko Oleg A. Ivashkevich Vadim E. Matulis Thierry Roisnel Vincent Dorcet Florence Mongin 《Molecules (Basel, Switzerland)》2021,26(20)
Five protocols were first compared for the copper-catalyzed C-N bond formation between 7-azaindole and aryl/heteroaryl iodides/bromides. The 1-arylated 7-azaindoles thus obtained were subjected to deprotometalation-iodolysis sequences using lithium 2,2,6,6-tetramethylpiperidide as the base and the corresponding zinc diamide as an in situ trap. The reactivity of the substrate was discussed in light of the calculated atomic charges and the pKa values. The behavior of the 1-arylated 7-azaindoles in direct iodination was then studied, and the results explained by considering the HOMO orbital coefficients and the atomic charges. Finally, some of the iodides generated, generally original, were involved in the N-arylation of indole. While crystallographic data were collected for fifteen of the synthesized compounds, biological properties (antimicrobial, antifungal and antioxidant activity) were evaluated for others. 相似文献
54.
Halim Yacine Khelifa Amira Berkal Messaoud Bouchair Abderrahmane 《Periodica Mathematica Hungarica》2022,85(1):109-127
Periodica Mathematica Hungarica - In this paper we present the well-defined solution of the following system of higher-order rational difference equations: $$\begin{aligned}... 相似文献
55.
Dr. Alessandro Sorrenti Dr. Zoubir El‐Hachemi Dr. Oriol Arteaga Dr. Adolf Canillas Dr. Joaquim Crusats Prof. Josep M. Ribo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(28):8820-8826
The aggregation of achiral sulfonatophenyl‐ and phenyl‐meso‐substituted diprotonated porphyrins to chiral J‐aggregates is a hierarchical noncovalent polymerization process preceded by a critical nucleation stage. This allows significant enantiomeric excesses by the formation of a few primary nuclei and the control of their growth by the effect that flows (imperfect mixing) have on the secondary nucleation of the J‐aggregate particles. In addition, the results strongly suggest that when only one species of aggregate predominates, the CD signals of the three excitonic bands in the visible region (around 420, 490, and 700 nm) show the same sign. Thus, differences on their relative sign would be due to the presence of different species. 相似文献
56.
57.
We prove the existence of solutions for the state depending convex sweeping processes in p-uniformly smooth and q-uniformly convex Banach spaces via new recent results on proximal analysis in reflexive smooth Banach spaces. 相似文献
58.
Ramdani M Lograda T Chalard P Chalchat JC Figueredo G 《Natural product communications》2011,6(1):87-92
Essential oils extracted from dried leaves of Cupressus dupreziana A. Camus, an endemic species in the Tassili n'Ajjer (Central Sahara of Algeria), were analyzed by gas chomatography coupled to mass spectrometry (GC-MS). Analyses were carried out on 164 trees of 26 natural populations in order to determine the intra-specific variability. Thirty-two terpenoids were identified, the major ones being alpha-pinene (11.5-44.2), delta3-carene (5.7-31.7) and germacrene-D (15.7-54.1). The terpenoid markers used made it possible to determine the individual patterns of chemotypic variability. This variability confirmed that genetic factors were not responsible for the decrease in the number of this species, the main reason probably being the Tassili n'Ajjer desertification. 相似文献
59.
The volatile compounds obtained by hydrodistillation of the aerial parts of Rosmarinus tournefortii De Noé. growing wild in the occidental region of Algeria were analyzed by GC/MS. Thirty-six compounds were characterized representing 95.6% of the essential oil, with camphor (37.6%), 1,8-cineole (10.0%), p-cymene-7-ol (7.8%), and borneol (5.4%) as the major components. The antimicrobial activity was evaluated against three pathogenic bacteria: Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus). The minimum inhibitory concentration (MIC; mg/mL) was determined by sub-culture on Muller Hinton agar plates. The essential oil exhibited strong antibacterial activity against E. coli and P. aeruginosa, and was also active against Staphylococcus aureus. 相似文献
60.
Nizar El?Hachemi Michel Gendreau Louis-Martin Rousseau 《Annals of Operations Research》2011,184(1):163-178
Scheduling problems in the forest industry have received significant attention in the recent years and have contributed many challenging applications for optimization technologies. This paper proposes a solution method based on constraint programming and mathematical programming for a log-truck scheduling problem. The problem consists of scheduling the transportation of logs between forest areas and woodmills, as well as routing the fleet of vehicles to satisfy these transportation requests. The objective is to minimize the total cost of the non-productive activities such as the waiting time of trucks and forest log-loaders and the empty driven distance of vehicles. We propose a constraint programming model to address the combined scheduling and routing problem and an integer programming model to deal with the optimization of deadheads. Both of these models are combined through the exchange of global constraints. Finally the whole approach is validated on real industrial data. 相似文献