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221.
This work is mainly an investigation of some of the liquid-to-solid properties of pure benzene on a restricted domain of high pressures (20.6< or =P< or =102.9 MPa). Newly obtained equilibrium experimental data and recently developed analytical equation of state are exploited and compared with each other and with previous experimental data. Curves fitted to the pressure, volume discontinuity, and enthalpy change at liquid-to-solid equilibrium points are provided. Concerning the metastable liquid benzene, both experimental and theoretical data for the minimum nucleation temperatures (limits of liquid metastability) are provided and correlated to each other. 相似文献
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224.
Mustapha?El JarroudiEmail author Alain?Brillard 《NoDEA : Nonlinear Differential Equations and Applications》2004,11(4):511-528
This work is mainly motivated by the study of shape optimization problems within the linear elastic framework and posed in general variable subdomains of a domain of
or 3. We precisely study the sets of measures which can be obtained through the relaxed optimization process. The case of an homogeneous and isotropic elastic material is specially emphasized. 相似文献
225.
Jihen Ben Slimen Mohammed Mehnaoui Samira Jebahi Khaled Boughzala Mustapha Hidouri 《印度化学会志》2022,99(6):100475
Ion-doping in hydroxyapatite bioceramics has attracted a lot of interest particularly for biomedical applications in repairing and replacing failure parts of musculoskeletal systems. Thus the multiple doping aims to mimic and resemble the chemical composition of the bone mineral component. Herein strontium hydroxyapatites bioceramics containing sodium Na+ and potassium K+ as cationic substituent and carbonate CO32? and fluoride as anionic substituent were synthesized and characterized by several analysis techniques. Therefore the chemical assays indicated that obtained compounds were less stoichiometric comparably to bone tissues. The X-ray diffraction diagrams and the infrared spectra revealed that pure phases of hydroxyfluorapatite containg the cited ions were obtained. The triple insertion of sodium, potassium and carbonate into the apatite structure leaded to the B-type carbonate apatite. The FE-SEM micrographs of the powders were formed by agglomerates. Moreover, the particles' morphology strongly depends on the ions nature and amount. The D-GTA curves indicated that the heating of the powders from the room temperature to 1000 °C didn't affect the structural and thermal stability of the materials apart from a partial decomposition of the apatite inducing the formation of the β-tristrontium phosphate phase and enhancing the biomaterial character of the materials. 相似文献
226.
A bone remodeling model taking into account the viscoelastic properties of the material is proposed. The nonlinear equations governing the evolution of the bone apparent density are solved by a finite difference method in the unidimensional case of a n-unit elements model. The results show the effects of the viscous damping on the structure for a controlled mechanical loading. To cite this article: S. Baïotto, M. Zidi, C. R. Mecanique 332 (2004). 相似文献
227.
The present work presents an experimental study on a free-falling rigid sphere in a quiescent incompressible newtonian fluid, placed in an oscillating frame. The goal of this investigation is to examine the effect of the history force acting on the sphere at small Reynolds numbers (Re2.5) and finite Strouhal numbers (1Sl20). The particle trajectory is measured by using a high-speed video camera and modern techniques of image processing. The average terminal velocity, the oscillation magnitude, and the phase shift with the oscillating frame are measured and compared with those obtained from theoretical approaches. The comparison is made by solving the equation of motion of the sphere with and without the history force. In addition to the significant role that this force plays in the momentum balance, it was found that the correction of the added mass force and the history force by the empirical coefficients of Odar and Hamilton (J Fluid Mech 18:302–314, 1964; J Fluid Mech 25:591–592, 1966) are not necessary in our Re and Sl ranges. The added mass is the same as that obtained by the potential flow theory and the history force is well predicted by the Basset expression (Treatise on hydrodynamics, 1888). 相似文献
228.
Damien Nativel Philipp Niegemann Jürgen Herzler Mustapha Fikri Christof Schulz 《Proceedings of the Combustion Institute》2021,38(1):901-909
Ethanol is known to be prone to pre-ignition in internal combustion engines under high-load conditions and its ignition shows large deviations from ideal, spatially, and temporally-homogeneous ignition in shock tubes at moderate temperatures (800–950 K). In this context, the ignition of stoichiometric ethanol/O2 mixtures with various levels of inert gas dilution was investigated in a high-pressure shock tube at ?20 bar between 800 and 1250 K. Ignition delay times were determined from spatially integral detection of chemiluminescence emission. Additionally, high-repetition-rate color imaging enabled the differentiation of the luminescence in time, space, and spectral range between various ignition modes. In the low-temperature range (800–860 K), different inhomogeneous ignition modes were identified. The addition of small amounts of helium into the undiluted fuel/air mixture was found to be efficient to mitigate pre-ignition, attributed to a variation in heat transfer and thus suppression of the build-up of local temperature inhomogeneities. The experiments in case of spatially homogeneous ignition show very good agreement with the predictions based on three detailed kinetics mechanisms (Zhang et al., CNF 190 (2018) 74, Frassoldati et al., CNF 159 (2012) 2295, and Zhou et al. CNF 197 (2018) 423), inhomogeneities, however, resulted in a shortening of the ignition delay times up to a factor of 2.6. 相似文献
229.
Farida Benmouna Ulrich Maschke Xavier Coqueret Mustapha Benmouna 《Macromolecular theory and simulations》1999,8(5):479-491
Model calculations of phase diagrams of side chain liquid crystal polymers (SCLCP) and low molecular weight liquid crystals (LMWLC) are presented. The polymer is assumed to have grafted side chain units characterized by a nematic‐isotropic transition temperature TNI 2, and the LMWLC presents also a similar transition at a temperature TNI 1 . The model calculations can accommodate for the cases where the latter two temperatures are comparable or widely different. For the sake of illustration, the case TNI 1 = 60°C and TNI 2 = 80°C is adopted here. The main point of interest here is to perform a comparative study of the equilibrium phase diagrams of SCLCP made either of linear free chains or crosslinked chains forming a single network. To our knowledge this is the first comparative study of the phase behavior of binary nematic mixtures involving linear and crosslinked polymer matrices which permits to clearly identify the effects of crosslinks present in the polymer matrix. The crosslinks attribute elasticity to the polymer constituent which induces important distortions in the phase diagram. To highlight these distortions, examples of hypothetical binary nematic mixtures are chosen involving both linear and crosslinked polymers with side chain mesogen units. The quadrupole interaction parameter between the two nematogens is related to individual parameters via a geometric average ν212 = κν11ν22 with a coupling parameter κ. Different values of this parameter are considered and the impact of coupling strength on the phase diagram is discussed for crosslinked and linear polymers. 相似文献
230.
This work discusses the static and dynamic scattering properties of (A-B)r ring diblock copolymer chains in the semi-dilute solutions. The case of a symmetric diblock is considered in details. The results show substantial differences with respect to linear diblock copolymers. This is mainly due to the effect of connectivity of the chain extremities A and B leading to different conformations for both types of architectures. The additional entropic interaction in cyclic chains induces a decrease of the elastic scattering intensity and a shift of the location of its maximum to a higher q value. As for the dynamics, the fact that the two extremities are connected speeds up the frequency of the interdiffusion mode and shifts its minimum to higher q value. A discussion of hydrodynamic interactions is also included. 相似文献