Nonlinear Vibrations and Chaos in Rectangular Functionally Graded Plates with Thermo-mechanical Coupling

We analyze the nonlinear dynamics of a simply supported, rectangular, and functionally graded plate in terms of a newly derived coupled system of thermo-elasticity and energy equations, which is then expanded here in derivations and explored for chaotic responses through a parameter study in the state space. The plate properties vary linearly in thickness. Three-dimensional stress-strain relations are considered in general case and nonlinear strain-displacement relations are deployed to account for the plate’s large deflection. A lateral harmonic force is applied on the plate, and there is a heat generation source within it and the surfaces are exposed to free convection. By integrating over the thickness, four new thermal parameters are introduced, which together with the midplane displacements constitute a system of seven partial differential equations. These equations are changed into ordinary differential equations in time using Galerkin’s approximation and solved by using the 4th order RungeKutta method. Finally, a parameter study is performed and the appropriate conditions resulting in chaotic solutions are determined by using numerical features such as the Lyapunov exponent and power spectrum

Flux-corrected dispersion-improved CABARET schemes for linear and nonlinear wave propagation problems

The new two-time-level dispersion improved CABARET scheme is developed as an upgrade of the original CABARET for improved wave propagation modelling in multiple dimensions and for nonlinear conservation laws including gas dynamics. The new upgrade retains many attractive features of the original CABARET scheme such as shock-capturing and low dissipation. It is simple for implementation in the existing CABARET codes and leads to a greater accuracy for solving linear wave propagation problems. A non-linear version of the dispersion-improved CABARET scheme is introduced to efficiently deal with contact discontinuities and shocks. The properties of the new linear and nonlinear CABARET schemes are analysed for numerical dissipation and dispersion error based on Von Neumann analysis and Pirrozolli's method. Numerical examples for one-dimensional and two-dimensional linear advection, the one-dimensional inviscid Burger's equation, and the isothermal gas dynamics problems in one and two dimensions are presented

Zonal jets in the Southern Ocean: a semi-analytical model based on scale separation

A reduced-order semi-analytic model of multiple zonal jets in the Southern Ocean is proposed based on the statistical approach and scale decomposition. By introducing two dominant scales in the vorticity equation, the model describes the large-scale and mesoscale dynamics using the explicit momentum dissipation in the horizontal and vertical directions. For validation and physical insights, the results of the reduced-order model are compared with solutions of two eddy-resolving ocean models: i) a realistic primitive-equation HYCOM (HYbrid Coordinate Ocean Model) simulation of the Southern Ocean and ii) an idealized quasi-geostrophic model of a shear-driven channel flow

Excitations of the Earth’s Chandler Wobble and Length Of Day by the Southern Ocean

In this paper, the effect of Southern Ocean on Chandler wobble and length of day excitations is investigated. To this end, the motion terms of excitations are calculated using the primitive equation ocean model, HYCOM (HYbrid Coordinate Ocean Model). The resulting excitations are analysed in time and frequency domains and compared to the previous studies for regional oceanic excitations of Chandler wobble and length of day. The excitations caused by the Southern Ocean are also compared with those caused by the global oceans in the same general circulation ocean model, HYCOM. Our results suggest that, amongst all oceanic regions, the Southern Ocean is a key contributor to both Chandler wobble and length of day excitations. The predicted excitations caused by the global oceans are also compared with geodetic observation of the Chandler wobble and length of day after subtraction of mass terms estimated from GRACE (Gravity Recovery and Climate Experiment) satellite gravimetry data

HPLC DETERMINATION OF PARTHENOLIDE AND APIGENIN CONTENTS VERSUS LABEL CLAIMS IN IRANIAN PRODUCTS

In this study parthenolide content of feverfew product (Tanamigraine capsule) and apigenin content of chamomile products (Chamomill drop, Kamisol solution, Prostatan drop, Prostatan tablet) were determined as effective compound by HPLC. Feverfew product was extracted by methanol/distilled de-ionized water (50: 50) and chamomile products by methanol. The HPLC operating conditions were C-18 reversed phase column (VP-ODS 250×4.6 mm, 5 mm), methanol/ distilled de-ionized water (60: 40) as the mobile phase at a flow rate of 1 ml/min and UV detection at 214 nm for parthenolide and 2% acetic acid: acetonitril with linear program 80 to 40 % of acetic acid 2% with a flow rate of 1 ml/min and UV detection at 275nm for apigenin. The amount of parthenolide and apigenin obtained in Tanamigraine capsules and chamomile products is 0.13- 016% and 0.04- 35% respectivel

Controlled Release Formulation of Indomethacin Prepared With Bee Glue Extracts

Purpose: To prepare and evaluate new sustained release formulations of indomethacin based on extracts of propolis (bee glue).Methods: Standardization of propolis (bee glue) extracts was performed by high performance liquid chromatography (HPLC) and determination of the values of fat and fixed oils. Several indomethacin capsule formulations (F1 - F18) containing varying amounts of chloroform (0.75 - 75 mg) and ethanol extracts (30 - 75 mg) of propolis were prepared. The dissolution rate of the formulations was evaluated by USP dissolution (rotating basket) method I and the release data subjected to various kinetic models. Probable interaction between the drug and propolis extracts was studied by differential scanning calorimetry (DSC).Results: The results show that, although the release rate of formulations F1 - F7 did not show any significant difference (p < 0.05) compared to F18 as blank, the other formulations did. DSC results indicate that incorporation of propolis extract in the formulations lowered indomethacin melting point by between 5 and 30 ºC, indicating interaction between the drug and the waxy extract. Kinetic analysis of the in vitro release data of the formulations showed that the best-fit drug release model varied with the drug:propolis extract ratio of the formulations.Conclusion: Formulation F13 (with equal proportion of drug and bee glue extract) came out best from the dissolution test for indomethacin extended-release capsules as it exhibited zero order kinetics. This fpormulation is therefore suitable for further development as a matrix formulation for controlled release.Keywords: Propolis (bee glue), Indomethacin, Controlled release, Zero order kinetics, Waxy material

Fast spectral solutions of the double-gyre problem in a turbulent flow regime

Several semi-analytical models are considered for a double-gyre problem in a turbulent flow regime for which a reference fully numerical eddy-resolving solution is obtained. The semi-analytical models correspond to solving the depth-averaged Navier–Stokes equations using the spectral Galerkin approach. The robustness of the linear and Smagorinsky eddy-viscosity models for turbulent diffusion approximation is investigated. To capture essential properties of the double-gyre configuration, such as the integral kinetic energy, the integral angular momentum, and the jet mean-flow distribution, an improved semi-analytical model is suggested that is inspired by the idea of scale decomposition between the jet and the surrounding flow

Excitation of the Earth's Chandler wobble by a turbulent oceanic double-gyre

We develop a layer-averaged, multiple-scale spectral ocean model and show how an oceanic double-gyre can communicate with the Earth's Chandler wobble. The overall transfers of energy and angular momentum from the double-gyre to the Chandler wobble are used to calibrate the turbulence parameters of the layer-averaged model. Our model is tested against a multilayer quasi-geostrophic ocean model in turbulent regime, and base states used in parameter identification are obtained from mesoscale eddy resolving numerical simulations. The Chandler wobble excitation function obtained from the model predicts a small role of North Atlantic ocean region on the wobble dynamics as compared to all oceans, in agreement with the existing observations

Green Synthesis of Silver Nanoparticles Induced by the Fungus Penicillium citrinum

Purpose: To evaluate a green process for the extracellular production of silver (Ag) nanoparticles synthesized and stabilized using Penicillium citrinum isolated from soil.Methods: The pure colonies of Penicillium citrinum were cultured in Czapek dox broth. The supernatant of the broth was examined for the ability to produce silver nanoparticles. The reactions were performed in a dark compartment at 28 oC. After 24 h, the synthesized silver nanoparticles were filtered through a membrane filter (0.45 ƒÊ) and characterized by UV-visible spectroscopy, fluorescence spectroscopy, photon correlation spectroscopy (PCS), scanning electron microscopy (SEM) and Fourier transformed infrared spectroscopy (FTIR) for particle size, shape and the presence of different functional groups in the nanoparticles.Results: The silver nanoparticles formed were fairly uniform in size with a spherical shape and a Zaverage diameter of 109 nm. FTIR spectra revealed the presence of amide linkage groups which were also found in the fungal extract itself.Conclusion: The current approach suggests that rapid synthesis of nanoparticles of silver nitrate would be suitable for developing a biological process for mass scale production of formulations.Keywords: Green synthesis, Penicillium citrinum, silver nanoparticles

Control Space Reduction and Real-Time Accurate Modeling of Continuum Manipulators Using Ritz and Ritz-Galerkin Methods

To address the challenges with real-time accurate modeling of multi-segment continuum manipulators in the presence of significant external and body loads, we introduce a novel series solution for variable-curvature Cosserat rod static and Lagrangian dynamic method. By combining a modified Lagrange polynomial series solution, based on experimental observations, with Ritz and Ritz-Galerkin methods, the infinite modeling state space of a continuum manipulator is minimized to geometrical position of a handful of physical points (in our case two). As a result, a unified easy to implement vector formalism is proposed for the nonlinear impedance and configuration control. We showed that by considering the mechanical effects of highly elastic axial deformation, the model accuracy is increased up to 6%. The proposed model predicts experimental results with 6-8% (4-6 [mm]) mean error for the Ritz-Galerkin method in static cases and 16-20% (12-14 [mm]) mean error for the Ritz method in dynamic cases, in planar and general 3D motions. Comparing to five different models in the literature, our approximate solution is shown to be more accurate with the smallest possible number of modeling states and suitable for real-time modeling, observation and control applications