195 research outputs found
S.E. Tran Thanh Dat : nouveau Ministre de l'Education nationale
No full text[ndlr] Reproduction de l'article biographique dédié au lettré Trần Thanh Đạt paru dans Indochine hebdomadaire illustré (1942). Né le 18 décembre 1891 au village de Tiên-nôn, canton de Mâu-tài, huyên de Phu-vang, province de Thua-thiên, de feu Tran-Nha, Quang-lôc-tu-khanh, et de feue Mme Huynh-thi-Diêu, S. E. Tran-thanh-Dat a fait de brillantes études qui l'ont conduit successivement au diplôme de l'Enseignement franco-annamite, obtenu en 1908, à l’École de Droit et d'Administration de Hanoi,..
S.E. Tran Thanh Dat : nouveau Ministre de l'Education nationale
No full text[ndlr] Reproduction de l'article biographique dédié au lettré Trần Thanh Đạt paru dans Indochine hebdomadaire illustré (1942). Né le 18 décembre 1891 au village de Tiên-nôn, canton de Mâu-tài, huyên de Phu-vang, province de Thua-thiên, de feu Tran-Nha, Quang-lôc-tu-khanh, et de feue Mme Huynh-thi-Diêu, S. E. Tran-thanh-Dat a fait de brillantes études qui l'ont conduit successivement au diplôme de l'Enseignement franco-annamite, obtenu en 1908, à l’École de Droit et d'Administration de Hanoi,..
Aqueous uranium activity removal by CoFe2O4 nanoparticles
No full textCobalt ferrite (CoFe2O4) nanoparticles have been prepared by the method of spraying-co-precipitation. The advantages of this approach are high productivity, excellent repeatability and high magnetic performances of the fabricated materials. The obtained materials were characterized by different techniques as X-ray diffraction, transmission electron microscopy, scanning electron microscopy. It was shown that CoFe2O4 has the face-centered cubic trevorite structure and particle size of about 18 nm. The vibrating sample magnetometer measurement had shown that obtained material had saturation magnetization of about 40 emu/g, remanences was 14 emu/g, and coercive forces (Hc) was 0.9 kOe. An investigation of uranium adsorption onto CoFe2O4 magnetic nanoparticles was studied in this research. This was confirmed by our experimental results using the method of inductively coupled plasma mass spectrometry. The pH effect, adsorption kinetics, and adsorption isotherms were examined in batch experiments. The sorption isotherm agreed well with the Langmuir model, having a maximum sorption capacity of 53.36 mg/g at pH = 6 and T = 298 K. Present research might eventually lead to a simple and low-cost method for fabricating magnetic materials and application for efficient removal of uranium from aqueous solution.(Copied from article
Figure 1 from: Tran TB, Han LN, Hai DV, Quang BH, Huong NTT, Ha BT, Hai TV, Rodda M (2020) Heterostemma cucphuongense (Apocynaceae, Asclepiadoideae), a new species from Vietnam. PhytoKeys 148: 119-124. https://doi.org/10.3897/phytokeys.148.50029
No full textFigure 1 Heterostemma cucphuongense T.B.Tran & Rodda A flowering branch B flower, view from above (adaxial) C flower, from underneath D corona, from above E ovary F pollinarium. (Photographs by N.Q. Dat, T.B. Tran, Thuong V.A., photo edit by M. Rodda
A modeling to understand where a vertical crack can propagate in pavements
No full textInternational audienceTo understand how a pre-existing vertical crack can propagate and damage pavements an alternative modeling is proposed to be used. For the multilayered pavement structures, the simplified modelling, named the multi-particle model of multi-layer materials (M4) with 5n equilibrium equations (n: number of pavement layers) is linked to the Boussinecq solution for the soil (Tran, 2004) (Chabot et al., 2005). This approach has the advantage of reducing the real 3D problem to the determination of regular plane fields (x,y) per layer and interface. Heavy loads, thermal loadings and thermal shrinkage phenomena have been integrated and validated with respect to finite element computations. It shows that the bond between layers near vertical cracks is damaged by normal and shear stresses. These combined effects are proposed to be medeled to understand corner crack initiation phenomenon of cemented concrete slab. Surface observations on concrete pavements with joints help the discussion
A modeling to understand where a vertical crack can propagate in pavements
No full textInternational audienceTo understand how a pre-existing vertical crack can propagate and damage pavements an alternative modeling is proposed to be used. For the multilayered pavement structures, the simplified modelling, named the multi-particle model of multi-layer materials (M4) with 5n equilibrium equations (n: number of pavement layers) is linked to the Boussinecq solution for the soil (Tran, 2004) (Chabot et al., 2005). This approach has the advantage of reducing the real 3D problem to the determination of regular plane fields (x,y) per layer and interface. Heavy loads, thermal loadings and thermal shrinkage phenomena have been integrated and validated with respect to finite element computations. It shows that the bond between layers near vertical cracks is damaged by normal and shear stresses. These combined effects are proposed to be medeled to understand corner crack initiation phenomenon of cemented concrete slab. Surface observations on concrete pavements with joints help the discussion
Simplified modelling of a cracked composite pavement
No full textInternational audienceFor the last ten years, new composite pavement structures have raised a significant interest. These are made of a concrete layer bonded on an asphalt sub-base. If the durability of this bond is proved, these structures benefit by a reduction both on the layers thickness and the cost (Pouteau et al., 2004). However, the restrained shrinkage of the concrete layer leads to vertical cracks. As the two materials have different elastic properties, stress singularities appear at the interface on the free edges generated by these cracks. To make a proper analysis of crack initiation and propagation in such a pavement structures, a simplified model (named the multi-particle model of multi-layer materials, M4) linked to the Boussinesq model for the soil has been developed (Tran et al., 2004). This approach has the advantage of reducing the real 3D problem to the determination of regular plane fields per layer and interface. To study the bond of composite pavement structures, an in-situ experiment has been done using an accelerated pavement loading facility. With that so-called M4-Boussinesq model, the aim of this study is to analysed the initial mechanical fields of that in-situ experiment
Modèle simplifié pour les chaussées fissurées multicouches
No full textMost of design pavement models can not be used to simulate cracking in pavements. This problem can be modelled by using 3D finite element methods, but such calculations can be very time-consuming. In the objective to build a software for the evaluation of cracked pavements, and design solution for rehabilitation, we propose here to use a simplified plate model for bending problem linked to the Boussinesq model for the soil. The complete algorithm is programmed in the Matlab software. This model gives, very quickly, good approximations of the design stress fields near interfaces and vertical cracks in comparison with 3D finite element calculations. Thermal and shrinkage problem are studied and validated. In the aim to simulate some fatigue problems, a method is presented to accelerate the calculations.Les modèles simplifiés usuels de dimensionnement des chaussées ne permettent pas de modéliser des chaussées fissurées et une modélisation par éléments finis 3D peut s'avérer très lourde. Dans l'objectif de construire un outil rapide et efficace de diagnostic et d'entretien des chaussées dégradées par le trafic, un modèle simplifié est proposé. Ce modèle repose sur un modèle simplifié adapté aux problèmes de flexion, le modèle multiparticulaire des matériaux multicouches (M4) à 5n équations (n: nombre total de couches) et le modèle élastique de Boussinesq pour le massif de sol. Programmé sous Matlab, dans le cas de bicouches de chaussées fissurées verticalement, ce modèle donne très rapidement d'excellents résultats par comparaison avec des calculs éléments finis 3D. Les cas de chargement de retrait thermique et de gradient thermique sont intégrés dans la modélisation et validés. Pour accélérer encore plus l'obtention des solutions dans le cadre de calculs multi- cycles, une méthode d'extrapolation des résultats du 2D pour estimer le 3D est exposée
STUDY ON INFLUENCE OF TEMPERATURE AND DURATION OF HYDROTHERMAL TREATMENT TO PROPERTIES OF NANO FERRITE NiFe2O4 MATERIALS
No full textNiFe2O4 superparamagnetic nanoparticles have been prepared by the method of spraying - co-precipitation subsequent by hydrothermal treatment. This procedure allowed to produce efficiently nanoparticles with high performances. Different techniques such as XRD, TEM, EDX, VSM were used to investigate the morphology, structure and magnetic properties of the obtained materials. It is shown that the materials have face-centered cubic trevorite structure, and their degree of crystallinity and magnetic properties improved with increasing temperature and time of hydrothermal treatment. After 32 hours of hydrothermal treatment at 160°C, NiFe2O4 nanomaterial has particle size of about 23 nm and saturation magnetization (Ms) of 49 emu/g.</jats:p
ADSORPTION OF URANIUM FROM AQUEOUS SOLUTION BY Cu0.5Ni0.5Fe2O4 – REDUCED GRAPHENE OXIDE NANOCOMPOSITES
No full textCu0.5Ni0.5Fe2O4 – reduced graphene oxide composites (CNF-rGO) as an efficient adsorbent for the adsorption of uranium (VI) have been synthesized by a two-steps methods. The structures and the physicochemical properties of adsorbents are characterized by Scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy (RAMAN) and Vibrating sample magnetometer (VSM) measurement. It was found that rGO were exfoliated and decorated homogeneously with CNF nanoparticles having diameters of 20 nm. The saturated magnetization (Ms) value was estimated to be 60 emu/g, remanences (Mr) and coercive forces (Hc) near to zero, indicating that obtained material is superparamagnetic. The pH effect, contact time and adsorption isotherms were examined in batch experiments. The adsorption isotherm agreed well with the Langmuir model, having a maximum adsorption capacity of 256 mg/g, at pH = 6, T = 298 K
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