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921.
The knowledge of response times of active material is essential for their efficient use as actuators. In this paper the heating and cooling times of a shape memory alloy wire (NiTi) under a constant load are predicted by the integration of the corresponding heat equation. The comparison with a ‘fictitious’ material with the same material characteristics but without phase transformation shows that the response times are longer for the SMA (around 2.7 times for heating and 1.5 times for cooling). To cite this article: N. Chaillet et al., C. R. Mecanique 332 (2004). 相似文献
922.
Il Ayranc Guillaume Pinguet Dany Escudi Nevin Seluk Rodolphe Vaillon Frdric Andr 《Experimental Thermal and Fluid Science》2007,31(8):839-847
Measurement of particle concentration by laser Doppler anemometry (LDA) is studied on a vertical air jet seeded by a powder disperser with controlled particle and air flow rates. Particle arrival rate is utilized to retrieve particle number densities from conventional LDA operation. The effect of polydisperse nature of the particles is assessed. Comparisons between measured and estimated particle number densities suggest that only a certain portion of the particle population with a particle size to fringe spacing ratio around unity can be detected. Results indicate that reliable measurement of absolute particle concentration is possible for a particle population of narrow size distribution with an average diameter equivalent to fringe spacing. Present number density measurement technique which is useful for practical purposes with conventional LDA systems is found to yield physically reasonable profiles in both laminar and turbulent regimes. 相似文献
923.
A simple one-dimensional model is used to simulate numerically the propagation oflinear and nonlinear waves in a deformable ceramic.The nummrical scheme used providesthe response in stress or strain and electric field within the sample and the voltage at aresistive external circuit connecting the two faces of the sample.Space-time diagrams of thepropagation are obtained for various mechanical loads.The voltage response obtainedagress well with experimental results in the linear regime.In the nonlinear one,thesteepening of the electromechanical wave yielding a shock wave is exhibited. 相似文献
924.
925.
M.Düldül 《应用数学和力学(英文版)》2003,24(8):945-949
The Steiner formula and the mixture area formula given by M(U|¨)ller were expressed under the one-parameter closed planar homothetic motions in the complex sense . Also, using the generalization of Steiner formula, the result of Holditch theorem for homothetic motions is got. In the case of the homothetic scale h≡1 the results given by M(U|¨)ller are obtained as a special case. 相似文献
926.
The present paper reports an experimental investigation on atomizing liquid flows produced by simplified cavity nozzles. The Weber number being kept low, the sprays produced by these injectors depend on the liquid flow characteristics only, and more precisely, on the non-axial kinetic energy and of the turbulent kinetic energy at the nozzle exit. The investigation reported here concentrates on the characterization of liquid flows during atomization by measuring the spatial variation of the local interface length and of the local interface fractal dimension. Both parameters were found representative of the physics of atomization process: they depend on the characteristics of the flow issuing from the nozzle and they are related to the subsequent drop size distribution. The local interface length is representative of the amount of liquid–gas interface surface area, and is a function of both the non-axial and the turbulent kinetic energies at the nozzle exit. The fractal dimension is representative of the tortuosity of the liquid–gas interface and, as expected, is mainly related to the turbulent kinetic energy at the nozzle exit. As far as the drop size distribution is concerned, it is found that the local interface length at the instant of break-up determines a representative drop diameter of some kind, whereas the fractal dimension at the same instant controls the dispersion of the distribution. 相似文献
927.
In this paper, a differentially heated square/cubic cavity is studied by performing three-dimensional direct numerical simulations. The first bifurcation observed at is due to the 3D vortex structures generated at the end regions of vertical boundary layers near the median plane. The main results of this Note are that the flow returns to a steady state for higher values of the Rayleigh number (7×107 and 108 for example) still exhibiting these 3D vortex structures, and that multiple steady flows which differ by their symmetry properties, are obtained for . However, the flow reverts to unsteadiness for . In this latter case, the instability is due to the vertical boundary layers. To cite this article: G. de Gassowski et al., C. R. Mecanique 331 (2003). 相似文献
928.
Cemal Özeroğlu Emine Doğan Gönül Keçeli 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):577-586
In this study, a crosslinked copolymer bearing sodium methacrylate functional groups has been proposed to remove Cs(I) ions
from aqueous solutions. For this purpose, the crosslinked copolymer of ethylene glycol dimethacrylate (EGDM) and methacrylic
acid (MA) containing 25% MA as weight percentage was synthesized by using benzoyl peroxide (BPO)-N,N-dimethyl aniline initiator system. The available carboxyl groups in copolymer were converted to the groups of sodium methacrylate
using 2 N NaOH. The adsorption behavior of cesium ions on the densely crosslinked poly(sodium methacrylate) from aqueous solutions
were investigated by the technique of ICP-MS measurements of cesium ions in solutions. Batch adsorption method was used to
analyze the Cs(I) adsorption as a function of parameters such as the amount of adsorbent, contact time, pH of solution, initial
Cs(I) concentration and temperature. The adsorption data were evaluated by the Freundlich, Langmuir and Dubinin–Radushkevich
(D–R) isotherms. The adsorption capacity and free energy change were calculated by using D–R isotherm. The adsorption data
obtained from experimental results have been tested by the fractional power, the Elovich, the pseudo-first order and the pseudo-second
order kinetic models. 相似文献
929.
Betül Taşdelen Aysun Ergun Fikret Büyükkaya 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):573-575
DOTA-conjugated peptides, such as [DOTA0, Tyr3]ocreotide (DOTATOC) and [DOTA0, Tyr3]octreotate (DOTATATE) can be labeled with radionuclides such as 90Y, 177Lu and 111In at high specific activities. These radiolabelled somatostatin analogues are used for peptide receptor radionuclide therapy
(PRRT). Currently, radio-high performance liquid chromatography (radio-HPLC) and radio-thin layer chromatography (radio-TLC)
are the methods of choice for the analysis of the labeled compounds. In literature, radiochemical purity of the radiolabelled
DOTATATE was investigated using gradient reversed-phase radio-HPLC. However, these studies indicate long retention time of
the radiolabelled compound of 14.52 min. In our study, a new simple and rapid reversed-phase isocratic system enables the
radiochemical purity of the radiolabelled DOTATATE within a few minutes. 相似文献
930.
Three-dimensional models of the quantum-mechanical current density J(B) , induced in the electron cloud of the C(10)H(10) pentaprismane molecule by a magnetic field B applied along the C(5) (a C(2)) symmetry axis, orthogonal to the pentagonal (a rectangular) face, and denoted by B(‖) (B(⊥)), have been constructed. Predictions of near Hartree-Fock quality are reported for the diagonal components of magnetic tensors, magnetizability (ξ), nuclear shielding of carbon (σ(C)) and hydrogen (σ(H)), and virtual shielding at the center of mass (σ(CM)). The complicated spatial features of the induced electronic current-density field have been rationalized and compactly described via stagnation graphs that elucidate the details of its topological structure. A representation of J(B) is obtained by three-dimensional perspective plots and by planar maps visualizing phase portraits of electron flow in a series of molecular domains. Both streamline J(B) /|J(B) | and modulus |J(B) | are analyzed. These graphic tools illustrate the competition between diatropic and paratropic regimes which determine the magnitude of various components of magnetizability and magnetic shielding of hydrogen and carbon nuclei. Shielding density maps show that the differential Biot-Savart law explains magnetic shielding at hydrogen and carbon nuclei, and virtual shielding at ring and cage centers. Similarities and/or contrasting ring current effects on magnetotropicity are discussed by a comparison with triprismane C(6)H(6) and cubane C(8)H(8) . 相似文献