Nonlinear modeling and control of flexible-link manipulators subjected to parametric excitation

This paper presents nonlinear dynamic modeling and control of flexible-link manipulators subjected to parametric excitation. The equations of motion are obtained using the Lagrangian-assumed modes method. Singular perturbation methodology is developed for the nonlinear time varying equations of motion to obtain a reduced-order set of equations. Control strategies, computed torque control and a composite control, based on the singular perturbation formulation developed, are utilized to reduce mechanical vibrations of the flexible-link and enable better tip positioning. Under the composite control technique, the effect of the value of perturbation parameter on the control signal is investigated. Numerical simulations supported by real-time experiments show that the singular-perturbation control methodology developed for the nonlinear time-varying system offers better system response over the computed torque control as the manipulator is commanded to follow a certain trajectory.     

Lyapunov-based control and trajectory tracking of a 6-DOF flapping wing micro aerial vehicle

Nonlinear Dynamics - In this work, a high-fidelity nonlinear and time-periodic six degrees-of-freedom dynamic model of a flapping wing micro aerial vehicle has been developed. The model utilized...     

Synthesis of chromenone,pyrimidinone, thiazoline,and quinolone derivatives as prospective antitumor agents

Hydrazide-hydrazone namely, 2-cyano-N′-((1-phenyl-3-[thiophen-2-yl]-1H-pyrazol-4-yl)methylene)acetohydrazide (3) underwent a series of reactions with some chemical reagents to construct new biologically active N-heterocycles, for example, chromenone, benzochromenone, thiazoline, and quinolone derivatives. Treating the nitrile derivative 3 with 2,4-dichlorobenzaldehyde and pyrazole aldehyde 1 afforded the corresponding condensed products. Some of the synthesized compounds were screened for their in vitro antitumor activities against two different human tumor cell lines including hepatocellular liver carcinoma (HepG2) and breast adenocarcinoma (MCF7) activities. Compound 3 was the most potent against the two tumors.     

An efficient ultrasonic synthetic approach,DFT study,and molecular docking of 6a-hydroxy-9-nitro-6,6a-dihydro-isoindolo[2,1-a] quinazoline-5,11-dione derivatives as algaecides for refining wastewater

In the present work, reaction of 3-nitrophthalic anhydride with anthranilic acid to afford the corresponding anthranil that is treated with acetic anhydride that yielded the 2-benzoxazinonyl-5-nitrobenzoic acid (BNBA) could be isomerized to the stereogenic 9-nitrobenzoxazinone[2,3-a]isoindolinone acetate (NBIA) via basic reaction conditions. A reaction of the BNBA→NBIA was allowed with series of nitrogen nucleophiles such as formamide and hydrazine derivatives, for example, hydrazine hydrate, hydroxyl amine, acetic hydrazide, thiosemicarbazide, thiocarboihydrazide, and some amino acid, for example, glycine, alanine, and some aliphatic amine, for example, octyl amine, decyl amine, and aromatic amine, for example, aniline, o-toluidine, 4-aminobenzoic acid, and carbon nucleophiles such as malononitrile and diethylmalonate. The basicity of previous nucleophiles and thermal stability of the products can be controlled on the course of reaction. The chemical structure of the synthesized compounds can be confirmed by micro-analytical, spectral data, and they are optimized by quantum chemical parameters (DFT study) to identify the thermal stability of the products. The data obtained from the molecular modeling were correlated with those obtained from the biological screening. A novel sequence of quinazoline derivatives were synthesized, evaluated for their algaecides activity against compounds 1 , 2b , and 6 that showed the highest algaecides activities of this series with relatively low toxicity in the median lethal dose test. The obtained results proved that the most active compounds could be useful models for future design, adaptation, and investigation to construct more active analogs.