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231.
232.
An‐Jian Xie Yuan‐Feng Yang Cheng‐Li Yao Yu‐Hua Shen Yong‐Mei Yang Xue‐Rong Yu Chun‐Yan Zhang Xue‐Mei Zhu 《Crystal Research and Technology》2006,41(12):1214-1218
In our experiments, the thermodynamic effect of calcium binding proteins (CBP) on the growth of calcium carbonate (CaCO3) was studied in vitro. The CaCO3 crystals obtained in systems with and without CBP were characterized by scanning electron microscope (SEM), Fourier Transform Infrared spectrograph (FT‐IR) and powder X‐ray diffractometer (XRD). The kinetic process was studied by monitoring the conductivity and pH value, which revealed the obvious inducement effect of CBP on the CaCO3 crystals growth, and the possible formation mechanism of CaCO3 in CBP solution was discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
233.
The thermal, phase transition and spectral studies of erythromycin A dihydrate and acetone solvate were performed by Differential Scanning calorimetry (DSC), Thermo Gravimetry (TG‐DTA), X‐Ray Powder Diffraction (XRPD) and Fourier Transform Infra‐Red (FTIR) spectrum. The non‐thermal kinetic analysis of erythromycin A dihydrate was carried out by DSC at different heating rates in dynamic nitrogen atmosphere. The result showed that heating rate has substantial influence on the thermal behavior of erythromycin dihydrate. The Arrhenius parameters were estimated according to the Kissinger method. Corresponding to dehydration of dihydrate, melting of dehydrated dihydrate, phase transition from dehydrated dihydrate to anhydrate, and melting of anhydrate, the calculated activation energy were 39.60, 269.85, 261.23, and 582.16 kJmol–1, the pre‐exponential factors were 3.46 × 103, 8.06 × 1032, 9.23 × 1030, and 7.29 × 1063 s–1, respectively. Ozawa method was used to compare activation energy values calculated by Kissinger method. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
234.
The time-dependent electro-viscoelastic performance of a circular dielectric elastomer (DE) membrane actuator containing an inclusion is investigated in the context of the nonlinear theory for viscoelastic dielectrics. The membrane, a key part of the actuator, is centrally attached to a rigid inclusion of the radius a, and then connected to a fixed rigid ring of the radius b. When subject to a pressure and a voltage, the membrane inflates into an out-of-plane shape and undergoes an inhomogeneous large deformation. The governing equations for the large deformation are derived by means of non-equilibrium thermodynamics, and viscoelasticity of the membrane is characterized by a rheological spring-dashpot model. In the simulation, effects of the pressure, the voltage, and design parameters on the electromechanical viscoelastic behaviors of the membrane are investigated. Evolutions of the considered variables and profiles of the deformed membrane are obtained numerically and illustrated graphically. The results show that electromechanical loadings and design parameters significantly influence the electro-viscoelastic behaviors of the membrane. The design parameters can be tailored to improve the performance of the membrane. The approach may provide guidelines in designing and optimizing such DE devices. 相似文献
235.
236.
混凝土材料动态性能的经验公式、强度理论与唯象本构模型 总被引：13，自引：0，他引：13
混凝土是一种应用广泛的结构工程材料, 其材料组份复杂、变化因素多, 因而力学特性也复杂多变. 动linebreak态/强冲击载荷作用下, 还涉及了材料应变率敏感效应和静水压力相关特性等诸多影响因素, 使得其本构理论的研究更加困难. 本文中, 回顾了近20多年来混凝土材料动态力学特性和本构关系研究方面的进展状况, 主要总结了混凝土材料动态本构特性研究中的经验公式、强度理论和本构模型, 并在分析比较的基础上给出了相应的讨论和评述. 相似文献
237.
T.M.A. EL‐Mistikawy F.M.N. El‐Fayez 《ZAMM - Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik》2013,93(9):706-712
An electrically conducting fluid is driven by a rotating disk, in the presence of a magnetic field that is strong enough to produce significant Hall currents. The disk is porous, allowing mass transfer through suction or injection. The limiting behavior of the flow is studied, as the magnetic field strength grows indefinitely. The flow variables are properly scaled, and uniformly valid asymptotic expansions of the velocity components are obtained through parameter straining. The leading order approximations show sinusoidal behavior that is decaying exponentially, as we move away from the disk surface. The two‐term expansions of the radial and azimuthal surface shear stress components, as well as the far field inflow speed, compare well with the corresponding finite difference solutions; even at moderate magnetic fields. 相似文献
238.
Mechanical behavior and microstructure evolution of polycrystalline copper with nano-twins were investigated in the present work by finite element simulations. The fracture of grain boundaries are described by a cohesive interface constitutive model based on the strain gradient plasticity theory. A systematic study of the strength and ductility for different grain sizes and twin lamellae distributions is performed. The results show that the material strength and ductility strongly depend on the grain size and the distribution of twin lamellae microstructures in the polycrystalline copper. 相似文献
239.
This paper is concerned with the dynamic behaviors of wave propagation in layered periodic composites consisting of piezoelectric and piezomagnetic phases. The dispersion relations of Lamb waves axe derived. Dispersion curves and displacement fields are calculated with different piezoelectric volume fractions. Numerical results for BaTiO3/CoFe2O4 composites show that the dispersion curves resemble the symmetric Lamb waves in a plate. Exchange between the longitudinal （i.e. thickness） mode and coupled mode takes place at the crossover point between dispersion curves of the first two branches. With the increase of BaTiO3 volume fraction, the crossover point appears at a lower wave number and wave velocity is higher. These findings are useful for magnetoelectric transducer applications. 相似文献
240.
在总结了型钢混凝土(SRC)柱承载力计算一般方法的基础上,针对T形型钢混凝土柱,结合中国现行规范,分析了此种柱的受力特点和破坏模式,提出T形型钢混凝土柱正截面极限承载力的计算方法,并采用该方法对一T形型钢混凝土柱的承载力进行验算. 结果表明与试验数据吻合较好,说明本文方法具有较好的精确度和适用性. 相似文献