Jacobian matrix for solving water distribution system equations with the Darcy-Weisbach head-loss model

Corrected by:Erratum: Jacobian Matrix for Solving Water Distribution System Equations with the Darcy-Weisbach Head-Loss Model, in Vol. 143, Issue 9, 08217002. There is a typographical error in Table 5. The formula for Case 3, the turbulent region (R≥4,000) in that table of the published paper.The widely used Todini and Pilati method for solving the equations that model water distribution systems was originally developed for pipes in which the head loss is modeled by the Hazen-Williams formula. The friction factors in this formula are independent of flow. Rossman's popular program EPANET implements elements of the Todini and Pilati algorithm, but when the Darcy-Weisbach head-loss formula is used, it does not take into account the dependence of the friction factors on the Reynolds number, and therefore flow, in computing the Jacobian. We present the correct Jacobian matrix formulas, which must be used in order to fully account for the friction factor's dependence on flow when the Todini and Pilati method is applied with the Darcy-Weisbach head-loss formula. With the correct Jacobian matrix the Todini and Pilati implementation of Newton's method has its normally quadratic convergence restored. The new formulas are demonstrated with an illustrative example. © 2011 American Society of Civil Engineers.Angus Simpson and Sylvan Elha

Morphology and Photoluminescence of HfO2Obtained by Microwave-Hydrothermal

In this letter, we report on the obtention of hafnium oxide (HfO2) nanostructures by the microwave-hydrothermal method. These nanostructures were analyzed by X-ray diffraction (XRD), field-emission gum scanning electron microscopy (FEG-SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDXS), ultraviolet–visible (UV–vis) spectroscopy, and photoluminescence (PL) measurements. XRD patterns confirmed that this material crystallizes in a monoclinic structure. FEG-SEM and TEM micrographs indicated that the rice-like morphologies were formed due to an increase in the effective collisions between the nanoparticles during the MH processing. The EDXS spectrum was used to verify the chemical compositional of this oxide. UV–vis spectrum revealed that this material have an indirect optical band gap. When excited with 488 nm wavelength at room temperature, the HfO2nanostructures exhibited only one broad PL band with a maximum at around 548 nm (green emission)

Design of canals

The book presents firsthand material from the authors on design of hydraulic canals. The book discusses elements of design based on principles of hydraulic flow through canals. It covers optimization of design based on usage requirements and economic constraints. The book includes explicit design equations and design procedures along with design examples for varied cases. With its comprehensive coverage of the principles of hydraulic canal design, this book will prove useful to students, researchers, and practicing engineers. End-of-chapter pedagogical elements make it ideal for use in graduate courses on hydraulic structures offered by most civil engineering departments across the world