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排序方式: 共有152条查询结果,搜索用时 31 毫秒
81.
Nicolas Javahiraly Ayoub Chakari Lionel Calegari Patrick Meyrueis 《Optics & Laser Technology》2004,36(3):239-243
We propose a new optical method for the determination of the rigidity modulus G of solid materials. The rigidity modulus is determined by measuring the twisted angle θ as a response of the material sample, depending on the applied force. The measuring of this twisted angle can be carried out by using an adapted polarimetric sensor. The effective measurement of rigidity modulus G for aluminum, Plexiglas and steel was experimentally obtained 1.4464×1010,0.99417×109 and 1.0395×1011 N m, respectively. The study has demonstrated the effective usefulness of our method for evaluating the rigidity modulus. A good agreement between the theoretical and experimental results was achieved. 相似文献
82.
Imine macrocyclic ligand M1 was involved in homo‐ and co‐polymerization of some vinyl monomers via atom transfer radical polymerization technique (ATRP). Hereby, vinyl acetate, styrene and methyl acrylate monomers were homopolymerized. On the other hand, they were involved in copolymerization with MMA. M1∶CuBr∶initiator∶monomer percentages were 1∶2∶4∶400. 1HNMR confirmed the structures of the resulting polymers. The thermal behaviors of some selected polymers were studied. 相似文献
83.
The free-vibration behavior of symmetrically laminated fiber-reinforced composite beams with different boundary conditions
is examined. The effects of shear deformation and rotary inertia, separately and/or in combination, on the free-vibration
properties of the beams are investigated. The finite-difference method is used to solve the partial differential equations
describing the free-vibration motion in each case. The effect of shear deformation on the natural frequencies is considerable,
especially for higher frequencies, whereas the influence of rotary inertia is less significant. The study includes comparisons
with results available in the literature. In addition, the impact of such factors as the span/depth ratio, fiber orientation,
stacking sequence, and material type on free vibrations of the composite beams is investigated.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 42, No. 3, pp. 331–346, May–June, 2006. 相似文献
84.
Mahmoud Filali 《Journal of Functional Analysis》2007,250(1):144-166
The paper proposes a unified approach to many key theorems proved in the last twenty years in different areas of abstract harmonic analysis. This approach is based on the so-called slowly oscillating functions which were introduced in coarse geometry. In addition to this method being the most natural and simple, it also leads to the generalisation of some of the results and to the achievement of some new results. Several of these results concern the topological centres of convolution algebras and semigroup compactifications. 相似文献
85.
Pereira CL Pedroso EF Doriguetto AC Ellena JA Boubekeur K Filali Y Journaux Y Novak MA Stumpf HO 《Dalton transactions (Cambridge, England : 2003)》2011,40(3):746-754
Three new bimetallic oxamato-based magnets with the proligand 4,5-dimethyl-1,2-phenylenebis(oxamato) (dmopba) were synthesized using water or dimethylsulfoxide (DMSO) as solvents. Single crystal X-ray diffraction provided structures for two of them: [MnCu(dmopba)(H(2)O)(3)](n)·4nH(2)O (1) and [MnCu(dmopba)(DMSO)(3)](n)·nDMSO (2). The crystalline structures for both 1 and 2 consist of linearly ordered oxamato-bridged Mn(II)Cu(II) bimetallic chains. The magnetic characterization revealed a typical behaviour of ferrimagnetic chains for 1 and 2. Least-squares fits of the experimental magnetic data performed in the 300-20 K temperature range led to J(MnCu) = -27.9 cm(-1), g(Cu) = 2.09 and g(Mn) = 1.98 for 1 and J(MnCu) = -30.5 cm(-1), g(Cu) = 2.09 and g(Mn) = 2.02 for 2 (H = -J(MnCu)∑S(Mn),(i)(S(Cu,i) + S(Cu),(i-1))). The two-dimensional ferrimagnetic system [Me(4)N](2n){Co(2)[Cu(dmopba)](3)}(n)·4nDMSO·nH(2)O (3) was prepared by reaction of Co(II) ions and an excess of [Cu(dmopba)](2-) in DMSO. The study of the temperature dependence of the magnetic susceptibility as well as the temperature and field dependences of the magnetization revealed a cluster glass-like behaviour for 3. 相似文献
86.
87.
Sukhanova T. E. Vylegzhanina M. E. Volkov A. Ya. Gasilova E. R. Kutin A. A. Samy Moshera Abdallah Heba M. Ayoub Magdy M. H. 《Technical Physics》2019,64(12):1729-1737
Technical Physics - The morphology, structure, and optical properties of composites with biodegradable polymeric particles, which are based on poly-ε-caprolactone–polyvinyl alcohol... 相似文献
88.
Philippe Gaborit Ayoub Otmani Hervé Talé Kalachi 《Designs, Codes and Cryptography》2018,86(7):1391-1403
Encryption schemes based on the rank metric lead to small public key sizes of order of few thousands bytes which represents a very attractive feature compared to Hamming metric-based encryption schemes where public key sizes are of order of hundreds of thousands bytes even with additional structures like the cyclicity. The main tool for building public key encryption schemes in rank metric is the McEliece encryption setting used with the family of Gabidulin codes. Since the original scheme proposed in 1991 by Gabidulin, Paramonov and Tretjakov, many systems have been proposed based on different masking techniques for Gabidulin codes. Nevertheless, over the years most of these systems were attacked essentially by the use of an attack proposed by Overbeck. In 2005 Faure and Loidreau designed a rank-metric encryption scheme which was not in the McEliece setting. The scheme is very efficient, with small public keys of size a few kiloBytes and with security closely related to the linearized polynomial reconstruction problem which corresponds to the decoding problem of Gabidulin codes. The structure of the scheme differs considerably from the classical McEliece setting and until our work, the scheme had never been attacked. We show in this article that for a range of parameters, this scheme is also vulnerable to a polynomial-time attack that recovers the private key by applying Overbeck’s attack on an appropriate public code. As an example we break in a few seconds parameters with 80-bit security claim. Our work also shows that some parameters are not affected by our attack but at the cost of a lost of efficiency for the underlying schemes. 相似文献
89.
Larbi Filali Yamina Brahmi Jamal Dine Sib Fatiha Kail Yahya Bouizem Djamel Benlakehal Kacem Zellama Ahmed Bouhekka Aissa Kebab Larbi Chahed 《Surface and interface analysis : SIA》2019,51(5):531-540
Highly crystallized hydrogenated silicon layers were obtained via the treatment of hydrogenated polymorphous silicon films in a molecular hydrogen ambient. This contrasts other postdeposition studies that obtained nanocrystalline silicon films but necessitated either a plasma activation or high-temperature annealing. The structure of the samples was analyzed by Raman spectroscopy to determine the crystallite volume fraction, which was found to increase up to 80% within 1 hour of treatment. Atomic force microscopy (AFM) showed that the roughness of the surfaces was found to increase after the H2 treatment. Optical transmission and spectroscopic ellipsometry revealed the pronounced porosity of the films characterized by a static refractive index that is below three, which is a low value for hydrogenated silicon films and a void fraction that is around 15% in the bulk of the films. The effect of the hydrogen molecules on the structure of the films was discussed in terms of the compressive stress exerted by the molecules, trapped in structural inhomogeneities, on the amorphous tissue. It is suggested that for this process to take effect, the films need to be porous and that the amorphous network needs to be in a “relaxed” state. 相似文献
90.
Ayoub Taavoni‐Gilan 《中国化学会会志》2019,66(6):600-607
In this study, we synthesized ofloxacin‐loaded MnFe2O4 nanoparticles (NPs) surface modified with chitosan (CS‐MnFe2O4) for prolonged antibiotic release in a controlled manner. It was found that the synthesized CS‐MnFe2O4 was spherical in shape with an average size of 30–50 nm, low aggregation, and good magnetic responsibility. An in vitro drug loading and release kinetics study reveals that the drug delivery system can take 86% of drug load and can release ofloxacin over a sustained period of 3 days. The release kinetics study reveals that the drug follows zero order kinetics and the mechanism of drug release is diffusion‐controlled type. These results indicated that CS‐MnFe2O4 NPs with pH‐sensitive properties can be used as candidates for intestinal targeted drug delivery through oral administration by avoiding the drug release in the highly acidic gastric fluid region of the stomach. 相似文献