Multilayer beams: A geometrically exact formulation

Summary We review and extend our recent work on a new theory of multilayer structures, with particular emphasis on sandwich beams/1-D plates. Both the formulation of the equations of motion in the general dynamic case and the computational formulation of the resulting nonlinear equations of equilibrium in the static case based on a Galerkin projection are presented. Finite rotations of the layer cross sections are allowed, with shear deformation accounted for in each layer. There is no restriction on the layer thickness; the number of layers can vary between one and three. The deformed profile of a beam cross section is continuous, piecewise linear, with a motion in 2-D space identical to that of a planar multibody system that consists of three rigid links connected by hinges. With the dynamics of this multi (rigid/flexible) body being referred directly to an inertial frame, the equations of motion are derived via the balance of (1) the rate of kinetic energy and the power of resultant contact (internal) forces/couples, and (2) the power of assigned (external) forces/couples. The present formulation offers a general method for analyzing the dynamic response of flexible multilayer structures undergoing large deformation and large overall motion. With the layersnot required to have equal length, the formulation permits the analysis of an important class of multilayer structures with ply drop-off. For sandwich structures, an approximated theory with infinitesimal relative outer-layer rotations superimposed onto finite core-layer rotation is deduced from the general nonlinear equations in a consistent manner. The classical linear theory of sandwich beams/1-D plates is recovered upon a consistent linearization. Using finite element basis functions in the Galerkin projection, we provide extensive numerical examples to verify the theoretical formulation and to illustrate its versatility. Dedicated to the memory of Professor Juan Carlos Simo, whose early demise is a great loss for the applied and computational mechanics community This paper was solicited by the editors to be part of a volume dedicated to the memory of Juan Simo.     

Spontaneously created ring structures in free-standing liquid crystal films and their dependence on temperature and material parameters

A rotating electric field can induce a spontaneous formation of ring structures in free-standing ferroelectric liquid crystal films. A phase delay between the field rotation and the director movement on the smectic cone is the reason for the ring creation. The appearance of these structures depends on the field parameters, on the material parameters of the liquid crystal compound used, and on the temperature. The temperature dependence of the pattern formation and of material parameters (spontaneous polarization, rotational viscosity, pitch) have been investigated in more detail. It could be shown that the rotational viscosity of the liquid crystal is the most important parameter with respect to the influence of temperature. The experimental results are compared with the theoretical interpretation of the ring formation.     

The Removal of Victoria Blue from Aqueous Solution by Adsorption on a Low-Cost Material

The use of perlite for the removal of victoria blue from aqueous solution at different concentration, ionic strength, pH and temperature has been investigated. Adsorption process is attained to the equilibrium within 1 h. It is found that the adsorption capacity of perlite samples for the removal of victoria blue increased by increasing pH and temperature, and decreased by expansion and ionic strength. The adsorption isotherms are described by means of the Langmuir and Freundlich isotherms. The adsorption isotherm was measured experimentally at different conditions, and the experimental data were correlated reasonably well by the adsorption isotherm of the Langmuir, and the isotherm parameters (Q _m and K) have been calculated for perlite samples as well. It is concluded that victoria blue is physically adsorbed onto the perlite. The removal efficiency (P) and dimensionless seperation factor (R) have shown that perlite can be used for removal of victoria blue from aqueous solutions, but unexpanded perlite is more effective.     

Using an adaptive neuro-fuzzy inference system-based interpolant for impulsive noise suppression from highly distorted images

A new impulsive noise (IN) suppression filter, entitled Adaptive neuro-fuzzy inference system (ANFIS)-based impulsive noise suppression Filter, which shows a high performance at the restoration of images distorted by IN, is proposed in this paper. The extensive simulation results show that the proposed filter achieves a superior performance to the other filters mentioned in this paper in the cases of being effective in noise suppression and detail preservation, especially when the noise density is very high.     

连续波激光辐照PV型HgCdTe探测器的新效应

 用连续波DF激光辐照PV型HgCdTe红外探测器，得到不同辐照功率密度下，探测器响应输出的一系列实验结果，观察到器件饱和以外的如探测器混沌、探测器单极化等一些新现象，这些结果与理论预期有着较大差别。给出了实验结果的初步解释，该实验结果为今后更好地研究PV型HgCdTe探测器提供了新的线索。     

Bosonic construction of the Lie algebras of some non-compact groups appearing in supergravity theories and their oscillator-like unitary representations

We give a construction of the Lie algebras of the non-compact groups appearing in four dimensional supergravity theories in terms of boson operators. Our construction parallels very closely their emergence in supergravity and is an extension of the well-known construction of the Lie algebras of the non-compact groups $\text{SP}\text{(2n,}\text{R}$ and $\text{SO}\text{(2n)}{}^1$ from boson operators transforming like a fundamental representation of their maximal compact subgroup U(n). However this extension is non-trivial only for n?4 and stops at n = 8 leading to the Lei algebras of SU(4) × SU(1, 1), SU(1, 1), SU(5, 1), SO(12)¹ and E₇(7). We then give a general construction of an infinite class of unitary irreducible representations of the respective non-compact groups (except for E₇₍₇₎ and SO(12)¹ obtained from the extended construction). We illustrate our construction with the examples of SU(5, 1) and SO(12)¹.     

Kinetic Analysis of Multi Enzyme Systems: A Case Study of the Closed System of Creatine Kinase, Hexokinase and Glucose 6-Phosphate Dehydrogenase

This paper describes a general methodology to handle closed multi enzyme systems using mixture of symbolic (which depends on the Gröbner Basis technique) and numerical computation methods. The applicability of the proposed method has been examined for the closed three-enzyme system of rabbit heart creatine kinase (EC 2.7.3.2), yeast hexokinase (EC 2.7.1.1) and human erythrocyte glucose 6-phosphate dehydrogenase (EC 1.1.1.49) using experimental data.     

Crucial role of electron correlation in both the upper and lower states in optical transitions

The merits of the various methods, used for the determination of relativistic energies, are discussed on the basis of numerical results. It is concluded that, at present, the perturbation approach, based on the Pauli approximation of the Dirac-Breit equation, is more accurate (up to Z < 48) than the variational approach. Furthermore it is expected that, in any case, the prediction of ionization potentials and energy levels will be equally satisfactory by either method. Consequently, and taking into account the importance of the correlation effects (not only because of the contribution of the correlation energy but also because of their influence on the prediction of the hyperfine structure), it is suggested that it may be worthwhile to direct more efforts towards multiconfigurational Dirac-Breit-Pauli calculations.This work has been supported in part by the National Research Council of Canada.