American University in Cairo

About: American University in Cairo is a education organization based out in Cairo, Egypt. It is known for research contribution in the topics: Population & Context (language use). The organization has 2472 authors who have published 5339 publications receiving 73741 citations.

Friction-Compensating Command Shaping for Vibration Reduction

Abstract: Fast and accurate point-to-point motion is a common operation for industrial machines, but vibration will frequently corrupt such motion. This paper develops commands that can move machines without vibration, even in the presence of Coulomb friction. Previous studies have shown that input shaping can be used on linear systems to produce point-to-point motion with no residual vibration. This paper extends command-shaping theory to nonlinear systems, specifically systems with Coulomb friction. This idea is applied to a PD-controlled mass with Coulomb friction to ground. The theoretical developments are experimentally verified on a solder cell machine. The results show that the new commands allow the proportional gain to be increased, resulting in reduced rise time, settling time, and steady-state error.

Hybrid plasmonic electro-optical modulator

Abstract: A high-performance CMOS compatible electro-optical modulator (EOM) is proposed, simulated and analyzed. The EOM is based on an asymmetric hybrid plasmonic waveguide on a silicon-on-insulator platform. Using the finite difference time domain simulation method, we obtained the transmission spectrum of the modulator. An insertion loss of 0.25 dB is achieved for a 5-μm-short modulator. The extinction ratio is optimized to be as high as 30 dB at a wavelength of 1.55 μm. Broadband operation of 600 nm is feasible since no resonator is deployed .

Entropy in bimolecular simulations: A comprehensive review of atomic fluctuations-based methods.

Abstract: Entropy of binding constitutes a major, and in many cases a detrimental, component of the binding affinity in biomolecular interactions While the enthalpic part of the binding free energy is easier to calculate, estimating the entropy of binding is further more complicated A precise evaluation of entropy requires a comprehensive exploration of the complete phase space of the interacting entities As this task is extremely hard to accomplish in the context of conventional molecular simulations, calculating entropy has involved many approximations Most of these golden standard methods focused on developing a reliable estimation of the conformational part of the entropy Here, we review these methods with a particular emphasis on the different techniques that extract entropy from atomic fluctuations The theoretical formalisms behind each method is explained highlighting its strengths as well as its limitations, followed by a description of a number of case studies for each method We hope that this brief, yet comprehensive, review provides a useful tool to understand these methods and realize the practical issues that may arise in such calculations

Controlled synthesis and characterization of hollow flower-like silver nanostructures.

Abstract: Background The synthesis of anisotropic silver nanoparticles is a time-consuming process and involves the use of expensive toxic chemicals and specialized laboratory equipment. The presence of toxic chemicals in the prepared anisotropic silver nanostructures hindered their medical application. The authors have developed a fast and inexpensive method for the synthesis of three-dimensional hollow flower-like silver nanostructures without the use of toxic chemicals.