Vibration analysis of a circular thin polymeric piezoelectric diaphragm with fluid interaction

This paper presents vibration analysis of a circular piezoelectric micro-plate in fluidic environment. PVDF film is used as the piezoelectric material. PVDF is a material with asymmetric matrix of piezoelectric constants and shows different piezoelectric properties in different directions. The governing equations, which are more complicated compared to piezo-ceramics, are derived. The boundary conditions for the plate are assumed fully clamped at outer edge, as is the case in many micro devices. Liquid is modeled as a damping foundation under the plate. The equations of motion are solved using generalized differential quadrature method to obtain Eigen frequencies and mode shapes of the plate. The results are compared by developed finite element analysis.     

Free Catalyzed Synthesis of 2,2′-Bipyridine via Ozonolysis Technique

The ozonation of a triple bond in organic compounds is rare in industry. The reaction is much more complicated to run, because ozone is an electrophilic agent and more likely to bind to the double bond compared to the triple bond in an organic compound. This may be a problem because some fine organic substances are very hard to synthesize and can only be solved by the ozonolysis technique of a triple-bond organic compound. In addition, oxidation by using ozone is also preferred because of the cleanliness and effectiveness of the reaction. A novel method for the synthesis of 2,2?-bipyridine was described, which involves ozonolysis of a 2-ethynylpyridine and is supported by a high-pressure reactor. The reaction proceeds via ozone attack on the acetylenic triple bond, cleavage, and free radical formation. The present study establishes the conditions for selective ozonolysis of 2-ethynylpyridine, leading to 2,2?-bipyridine. The 2,2?-bipyridine was characterized by gas chromatography flame ionization detector (GC-FID) and mass spectroscopy techniques. A novel suggested mechanism was used to explain the oxidation process. Analysis showed that the formation of oxidized product is shown when ozone is supplied in excess, which shows that the reaction between 2-ethynylpyridine and ozone is a first-order reaction, whe reby the result of the relationship only depends on the concentration of the starting material, which is 2-ethynylpyridine acts as the limiting reactant.     

Thermodynamic model for predicting phase equilibria of simple clathrate hydrates of refrigerants

In this communication, a thermodynamic model is presented for the study of the phase equilibria of clathrate hydrates of simple refrigerants. The van der Waals–Platteeuw solid solution theory is used to model the hydrate phase while it is assumed that vapor phase is an ideal gas of refrigerant ignoring its water content and the aqueous phase is considered as pure water (activity coefficient=1) ignoring aqueous solubility. The results through this model are successfully compared with the experimental data reported in the literature for clathrate hydrates of four refrigerants namely C₂H₂F₄ (1, 1, 1, 2-tetrafluoroethane or HFC-134a or R-134a), C₂H₄F₂ (1, 1-difluoroethane or HFC-152a or R-152a), CH₂F₂ (difluoromethane or HFC-32 or R-32), and C₂H₃Cl₂F (1,1-dichloro-1-fluoroethane or HCFC-141b or R-141b).     

Artificial Neural Network modeling of solubility of supercritical carbon dioxide in 24 commonly used ionic liquids

Application of supercritical CO₂ for separation of ionic liquids from their organic solvents or extraction of various solutes from ionic liquid solvents have found great interest during recent years. Knowledge of phase behaviors of the mixtures of supercritical CO₂+ionic liquids is therefore drastic in order to efficiently design such separation processes. In this communication, Artificial Neural Network procedure has been applied to represent the solubility of supercritical CO₂ in 24 mostly used ionic liquids. An optimized Three-Layer Feed Forward Neural Network using critical properties of ionic liquids and operational temperature and pressure has been developed. Application of this model for 1128 data points of 24 ionic liquids show squared correlation coefficients of 0.993 and average absolute deviation of 3.6% from experimental values for calculated/estimated solubilities. The aforementioned deviations show the prediction capability of the presented model.     

Axial response and material efficiency of tapered helical piles

Different techniques have been proposed to increase the bearing capacity of open-ended piles.Welding helices to the shaft and tapering the pile shaft could be used simultaneously to enhance the static and dynamic behaviors of these piles.This paper subjects the bearing capacity,stiffness,frictional behavior,and material efficiency of the tapered helical piles to scrutiny.Tapered helical piles are introduced herein as an alternative option to improve the material efficiency of hollow piles.Based on the Taguchi method,a series of experiments was designed and conducted.The axial responses of tapered helical piles are also investigated using finite element analyses.The results derived from loadedisplacement curves and strain gages are used to characterize the axial compression responses of tapered helical piles.The effects of tapered angle,helices diameter and helices distance are examined using dimensionless parameters,and the degree of contribution of these factors is calculated on each of the enumerated variables individually.Experimental results show that the shaft friction resistance of tapered helical piles increases continuously with the pile head settlement.Furthermore,the effect of tapered wall on the shaft friction resistance is more tangible at low stress levels.The results showed that the relative material efficiency factor of the optimum pile could be 2.5 times that of unoptimized pile with a similar quantity of material.     

A neuro‑observer‑based optimal control for nonaffine nonlinear systems with control input saturations

In this study, an adaptive neuro-observer-based optimal control (ANOPC) policy is introduced for unknown nonaffine nonlinear systems with control input constraints. Hamilton–Jacobi–Bellman (HJB) framework is employed to minimize a non-quadratic cost function corresponding to the constrained control input. ANOPC consists of both analytical and algebraic parts. In the analytical part, first, an observer-based neural network (NN) approximates uncertain system dynamics, and then another NN structure solves the HJB equation. In the algebraic part, the optimal control input that does not exceed the saturation bounds is generated. The weights of two NNs associated with observer and controller are simultaneously updated in an online manner. The ultimately uniformly boundedness (UUB) of all signals of the whole closed-loop system is ensured through Lyapunov’s direct method. Finally, two numerical examples are provided to confirm the effectiveness of the proposed control strategy.     

Best of Both Worlds: Synergistically Derived Material Properties via Additive Manufacturing of Nanocomposites

With an exponential rise in the popularity and availability of additive manufacturing (AM), a large focus has been directed toward research in this topic's movement, while trying to distinguish themselves from similar works by simply adding nanomaterials to their process. Though nanomaterials can add impressive properties to nanocomposites (NCs), there are expansive amounts of opportunities that are left unexplored by simply combining AM with NCs without discovering synergistic effects and novel emerging material properties that are not possible by each of these alone. Cooperative, evolving properties of NCs in AM can be investigated at the processing, morphological, and architectural levels. Each of these categories are studied as a function of the amplifying relationship between nanomaterials and AM, with each showing the systematically selected material and method to advance the material performance, explore emergent properties, as well as improve the AM process itself. Innovative, advanced materials are key to faster development cycles in disruptive technologies for bioengineering, defense, and transportation sectors. This is only possible by focusing on synergism and amplification within additive manufacturing of nanocomposites.     

The effect of ethoxylated nonyl phenols on viscosity of crude oil

In this study, viscosities of different crude oils was determined in the temperature range of (298–373 K) in presence of ethoxylated nonyl phenols as nonionic surfactant with ethoxy group numbers 4 and 9 (nonyl phenol 4 and nonyl phenol 9). Viscosity was measured using Viscolab PVT viscometer. Viscosity of crude oil decreased with the increase of concentration in the range of 0–1.4 g l^?1). The most radical change was observed in the presence of nonyl phenol 9. For both surfactants, the viscosities of crude oil decreased with the increase of temperature, but the effect of temperature on the viscosity of crude oil decreased when surfactant concentration increased. Because of the formation of mixed micellar aggregates, the effect of mixed surfactants on the reduction of viscosity was more obvious than individual surfactant, but mixed surfactants had very little sensitivity to the temperature than individual surfactant. The best mixture of two surfactants system was observed in the mass ratio of 3 for nonyl phenol 9 and nonyl phenol 4.