Equations of Motion of Planar Serial Chains of Rigid Bodies

In the present study, the equations of motion of planar serialchains that consist of a system of rigid bodies with all commontypes of kinematic joints are presented. The system of rigid bodiesis replaced by a dynamically equivalent constrained system ofparticles. The concepts of linear and angular momentums are used togenerate the equations of motion for the resulting equivalentconstrained system of particles without either introducing anyrotational coordinates or distributing the external forces and forcecouples over the particles. The method can be applied for open orclosed chains. An example of a closed chain is chosen to demonstratethe generality and simplicity of the proposed method.     

On the effectiveness of porosity on unsteady flow between parallel plates of a viscoelastic fluid under constant pressure gradient with heat transfer

The unsteady flow in a porous medium of an incompressible non-Newtonian viscoelastic fluid between two parallel horizontal non-conducting porous plates is studied with heat transfer. A sudden uniform and constant pressure gradient and uniform suction and injection through the surface of the plates are applied. The two plates are kept at different but constant temperatures, while the Joule and viscous dissipations are taken into consideration. Numerical solutions for the governing momentum and energy equations are obtained using finite difference approximations. The effect of the porosity of the medium, the parameter describing the non-Newtonian behavior, and the velocity of suction and injection on both the velocity and temperature distributions is examined.     

Toward enhanced wireless coexistence in ISM band via temporal characterization and modelling of 802.11b/g/n networks

This paper presents extensive experimental characterization and empirical modelling of 802.11 temporal behavior. A detailed characterization of 802.11b/g/n homogeneous and heterogeneous network traffic patterns is featured, including idle time distribution and channel utilization. A complete modelling of 802.11 networks in the 2.4 GHz Industrial, Scientific, and Medical band is also presented. Such information can assist the development of other wireless technologies aiming to utilize the crowded Industrial, Scientific, and Medical band more efficiently and to achieve enhanced wireless coexistence. In this work, models are derived for both homogeneous and heterogeneous 802.11 network idle time distributions. Also presented is a case study utilizing 802.15.4 ZigBee transmitter packet size that was adaptively modified based on channel idle time distribution. Results demonstrate superior ZigBee performance and significant enhancement in throughput. Copyright © 2016 John Wiley & Sons, Ltd.     

Spectroscopic Analyses and Antimicrobial Activity of Novel Ciprofloxacin and 7-Hydroxy-4-methylcoumarin,the Plant-Based Natural Benzopyrone Derivative

Coumarin is highly distributed in nature, notably in higher plants. The biological features of coumarin include antibacterial, anticancer and antioxidant effects. It is well known that metal ions present in complexes accelerate the drug action and the efficacy of organic therapeutic agents. The main aim of the current study is the synthesis of different complexes of the interaction between ciprofloxacin hydrochloride (CIP) and coumarin derivative 7-hydroxy-4-methylcoumarin (HMC) with Zr(IV). The chelates of CIP with Zr(IV) were prepared and characterized by elemental analysis, melting point, conductance measurements, spectroscopic techniques involving IR, UV-Vis, ¹H NMR, and thermal behavior (TG-DTG) in the presence of HMC, dimethylformamide (DMF), pyridine (Py), and triethylamine (Et₃N). Results of molar conductivity tests showed that the new synthesized complexes are electrolytes with a 1:1 or 1:2 electrolyte ratio, with the chloride ions functioning as counter ions. According to IR spectra, CIP acts as a neutral bidentate ligand with Zr(IV) through one carboxylato oxygen and the carbonyl group, HMC as a monodentate through the carbonyl group, and DMF through the oxygen atom of the carbonyl group and the N atom of Py and Et₃N. The thermal behavior of the complexes was carefully investigated using TG and DTG techniques. TG findings signal that water molecules are found as hydrated and coordinated. The thermal decomposition mechanisms proposed for CIP, HMC, and Zr(IV) complexes are discussed and the activation energies (E_a), Gibbs free energies (∆G*), entropies (∆S*), and enthalpies (∆H*) of thermal decomposition reactions have been calculated using Coats–Redfern (CR) and Horowitz–Metzeger (HM) methods. The studied complexes were tested against some human pathogens and phytopathogens, including three Gram-positive bacteria (Bacillus subtilis, B. cereus, Brevibacterium otitidis) and three Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae), and compared to the free CIP and HMC parent compounds.     

Performance of a backpropagation trained feedforward network on an MIMD architecture

Training of feedforward networks on sequential machines is a computationally expensive process. This has motivated the implementation of parallel versions of the backpropagation training algorithm on different parallel platforms in order to decrease the processing time required for training. In this paper, we are investigating the implementation of backpropagation on the Alex AVX-2 coarse-grained MIMD machine. A master–slave parallel implementation is carried out for the encoder–decoder benchmark problem. A communication model for the broadcasting/gathering is used to study the effect of using different topologies. Then the performance of the backpropagation algorithms is analyzed for different network sizes and numbers of processors when the nodes are arranged as a pipeline array and in a mesh topology. © 1998 John Wiley & Sons, Ltd.     

Robust model order reduction technique for MIMO systems via ANN‐LMI‐based state residualization

Even though model order reduction (MOR) techniques for linear dynamical systems are developed rather properly, there are still quite a lot of issues to be considered. This paper addresses a novel MOR technique for multi‐input multi‐output system with dominant eigenvalue preservation, which leads to controller cost minimization. The new technique is formulated based on an artificial neural network (ANN) prediction of an upper triangular form of the system state matrix A. Using the new system state matrix along with the linear matrix inequality (LMI) optimization method, a permutation matrix is obtained which leads to the new formulation of the complete system considered for MOR. Utilizing the non‐projection state residualization technique, a reduced model order is obtained. The proposed ANN‐LMI‐based MOR method is compared with well‐known reduction techniques such as the balanced Schur decomposition, proper orthogonal decomposition (POD), and state elimination through balanced realization. Copyright © 2010 John Wiley & Sons, Ltd.     

Dihydroxyaluminum Carboxylate Nanoparticles With Narrow Size Distribution: Synthesis,Characterization and Use for High Optical Transparency Protective Polymeric Coatings

Nano‐sized bis(dihydroxyaluminum)maleate particles (ALMAL) were prepared via a high‐temperature precipitation reaction from different Al‐alkoxides and maleic acid in different solvents. Variations in the reactants were carried out to identify the optimum reaction conditions that lead to particles <30 nm in diameter with narrow particle size distributions and without formation of a secondary amorphous phase. A disc centrifuge was used to characterize the particles in terms of particle size distribution. ALMAL‐containing, epoxy‐based nanocomposites were prepared with ALMAL‐loadings up to 30 wt.‐% and thermally cured. The cured coatings possessed excellent scratch and abrasion resistance, surface hardness and were highly transparent (T>95%). In order to study the effect of the nature of nanoparticles on the final properties of the coatings, aluminum malate (ALMALAT), and aluminum terephthalate (ALTEREPHTHAL) nanoparticles as well as the corresponding composite coatings were prepared and characterized. For comparison, surface‐modified silica nanoparticles were used to evaluate the mechanical and optical behavior of the produced nanocomposite coatings.

     

MHD flow and heat transfer in a rectangular duct with temperature dependent viscosity and hall effect

In the present paper the laminar fully developed MHD flow and heat transfer through a rectangular duct of a viscous incompressible electrically conducting fluid is studied. A constant pressure gradient and an external uniform magnetic field are applied and the Hall effect is taken into consideration. The fluid viscosity is assumed to be temperature dependent with the assumption of constant wall heat flux axially and constant wall temperature peripherally. A numerical solution for the governing non-linear partial differential equations is obtained. The effect of the Hall term and the variable viscosity on the velocity and temperature fields is examined.     

Coupled 1-D stress and thermal waves in temperature dependent nonlinear elastic and viscoelastic media*

Abstract

A general analysis is formulated for the closed loop coupled thermal and displacement viscoelastic 1-D wave problem. The proper inclusion of the highly temperature sensitive viscoelastic material properties renders the problem nonlinear, even though the displacements and material properties are considered to obey linear relations. In the present article. the previous analysis is enlarged and reformulated by (a) the inclusion of nonlinear elastic and viscoelastic constitutive relations as formulated in Hilton, (b) the addition of thermal waves to the displacement waves, and by (c) temperature dependent material density and viscoelastic moduli and compliances. The wave problem studied here is of significant importance in modeling, material characterization, determination of instantaneous moduli, nonlinear analytical solution protocols and the nonlinear interaction of temperature, material properties, and wave motions. Analytical and numerical solution protocols are presented and evaluated.     

Mode coupling and output beam quality of 100-400 μm core silica fibers

Propagation and mode coupling within relatively short (～1-10?m) large core, nominally multimode, fibers are of interest in a number of applications. In this research, we have studied the output beam quality and mode coupling in various fibers with core diameters of 100-400?μm and lengths of 2?m. Output beam quality (M2) and mode-coupling coefficients (D) have been studied for different clad dimensions, numerical apertures, and wavelengths. The mode-coupling coefficients have been determined based on modal power diffusion considerations. The results show that D scales approximately as the inverse square of the clad dimension and inverse square root of the wavelength. Output from a 2?m length fiber of 100?μm core and 660?μm clad fiber is close to single mode (M2=1.6), while output from a 200?μm core and 745?μm clad fiber also has high beam quality.