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The multi-effect-coupling pH-electric-stimuli (MECpHe) model for polyelectrolyte hydrogels subjected to coupled changes in the solution pH and an external electric field is reported. The model provides insight into the effect of changes on the deformation of the hydrogel and distribution of ionic species, electric potential, and fixed charge density, both inside the hydrogel as well as in the surrounding solvent.

In this paper, we study the effects of initial fixed-charge density on the response behavior of pH-sensitive hydrogels subjected to coupled stimuli, namely, solution pH and externally applied electric,field. This is the first instance in which a coupled stimuli numerical analysis has been carried out for these polymer gels, which are used as active sensing/actuating elements in advanced biomicroelectromechanical systems devices. In this work, a chemo-electro-mechanical formulation, termed the multi-effect-coupling pH-stimulus (MECpH) model is first presented. This mathematical model takes into account the ionic species diffusion, electric potential coupling, and large mechanical deformation. In addition, a correlation between the diffusive hydrogen ions and fixed-charge groups on the hydrogel polymeric chains is established based on the Langmuir absorption isotherm, and incorporated accordingly into the MECpH model. To solve the resulting highly nonlinear and highly coupled partial differential equations of this mathematical model the Hermite-Cloud method, a novel true meshless technique, is employed. To demonstrate the accuracy and robustness the MECpH model computed numerical results are compared with experimental data available from literature. Following this validation, several numerical studies are carried out to investigate the effects of initial fixed-charge density on the volumetric variations of these pH-stimulus-responsive hydrogels when immersed in buffered solutions. [DOI: 10.1115/1.2472370] Keywords: bioMEMS, pH-sensitive hydrogel, chemo-electro-mechanical coupling, ionic species diffusion, electric potential coupling, MECpH model meshless method

Based on the generalized differential quadrature (GDQ) method, this paper presents, for the first instance, the free-vibration behavior of a rotating thin truncated open conical shell panel. The present governing equations of free vibration include the effects of initial hoop tension and the centrifugal and Coriolis accelerations due to rotation. Frequency characteristics are obtained to study in detail the influence of panel parameters and boundary conditions on the frequency characteristics. Further, qualitative differences between the vibration characteristics of rotating conical panels and that of rotating full conical shells are investigated. To ensure the accuracy of the present results using the GDQ method, comparisons and verifications are made for the special case of a stationary panel. [DOI: 10.1115/1.1577600]

This report describes a left adrenal tumour in a 16 year old Chinese girl who presented with fever of unknown origin. The histological and ultrastructural features of the adrenal tumour [...]

Dynamic plastic response of a submarine oil pipeline to an underwater explosion bubble is studied in this paper. A detailed fluid-structure analysis is given to find the fluid forces acting on the pipeline. Assuming the pipeline is made from rigid, perfectly plastic material we obtain the hydroplastic equation governing the dynamic plastic deflection of such a pipeline. The equation is analytically solved. Three examples are given to discuss the features of the dynamic plastic response and the applicability range of the present analysis. The relation between the half pipe length and maximum permanent plastic deflection is also given. [S0021-8936(00)01004-7]

A finite element approach for predicting transient responses of layered structures to low-velocity impact is presented. Data demonstrate that both thickness and modulus ratios have effects on the impact response and influence structural damping of the flexural wave propagation.

A strip element method is presented for analyzing wave scattering by a crack in a composite laminate submerged in a fluid. In this method, the fluid and laminated plate are modeled using two-nodal-line and three-nodal-line strip elements, respectively. A system of governing equations of the fluid and solid strip elements in frequency domain are derived using a variational method and the Hamilton principle, which are converted as a set of characteristic equations in wave number domain by applying Fourier transform techniques. A particular solution to the equations is obtained using a modal analysis method in conjunction with inverse Fourier transform techniques. A complementary solution to the equations is found employing horizontal boundary conditions on cross sections at the crack tips. The addition of the particular and complementary solutions yields a general solution. Numerical examples are presented for immersed steel and composite plates with either a horizontal or a vertical crack. Computed results indicate that the fluid has considerable influence on the wave fields scattered by a crack in a composite laminate.

A simple procedure is proposed in this paper to estimate the global failure probabilities of a submarine oil pipeline subjected to underwater explosion shock wave. The deterministic response of a pipeline subjected to an underwater shock loading is first given by solving a simplified fluid-structure interaction problem. Compared with an FEM/BEM coupling model, the present method gives good results at much lower computational efforts. Then, the Monte Carlo method is used to find the global failure probabilities of the pipeline. Finally, a practical example is given.