Distribution System Protection with Decentralized Generation Introduced into the System

Cogeneration from renewable energy sources has been universally proposed as a partial alternative to the solution of our nation's energy problems. New technical, safety, and operational problems are introduced when this generation is placed into a distribution grid. Addressed is the problem of distribution system protection with the introduction of cogeneration sources and the changes and modifications which may be required in the application of present-day protection devices. A sample system is considered, and system protection and coordination with and without cogeneration has been calculated through a digital fault and system protection coordination program. The results indicate through the study of several systems that additional coordination and protection considerations will be required when sizable cogeneration sources are introduced to maintain a high degree of reliability and service continuity.     

Fast Thermal Generation Rescheduling

A new dynamic programming algorithm for fast rescheduling thermal generation is presented. The savings in computational times are brought about by the introduction of two new techniques: the variable truncation dynamic programming and the limitation of the solution space to be searched. Several examples on a 20 machine system are used to illustrate the application of the algorithm and to show that optimal solutions are obtained at significantly reduced computational times.     

Hybrid Amine-Functionalized Titania/Silica Nanoparticles for Solid-Phase Extraction of Lead,Copper, and Zinc from Food and Water Samples: Kinetics and Equilibrium Studies

In the present study, hybrid amine-functionalized titania/silica nanoparticles were employed as a new and novel adsorbent for solid-phase extraction of Pb²⁺, Cu²⁺, and Zn²⁺ ions prior to their determination using flame atomic absorption spectrometry. Under the best conditions (including adsorbent, 0.4 g; eluent, 5.0 mL nitric acid (HNO₃), 3.0 mol L^?1, 1.0 mL min^?1; and sample, pH 5.0, 3.0 mL min^?1), detection limits, adsorption capacities, and preconcentration factors were 0.12–0.24 μg L^?1, 7.1–20.7 mg g^?1, and 200, respectively. To predict the adsorption isotherms, different isotherm models were studied and the obtained results showed that the Langmuir model is the most suitable one to explain the experimental data. The kinetics of the reaction followed pseudo-second-order kinetic model. Thermodynamic parameters like free energy (ΔG ⁰) and enthalpy (ΔH ⁰) confirmed the spontaneous and exothermic nature of the process. The method was successfully applied for determination of the analytes in different food and water samples.     

Update on laser-assisted hair transplantation

OBJECTIVE: The aim of this study was to examine the laser parameters evaluated in previous studies with a larger patient group (n = 491), particularly with regard to patient-related and operation-related advantages and disadvantages. Particular attention was devoted to hair growth rate and the postoperative healing process. METHODS: The implant holes were created using an optomechanical, beam-focusing miniature scanner and a 80-W carbon dioxide laser. RESULTS: All patients in Norwood classification groups I, II, and III displayed proper hair growth. On an average of all patients treated, this occurred with a delay of some 4-6 weeks. Compared with the cold steel technique, the healing process was shortened by 3-4 days. CONCLUSIONS: Making allowances for the formula: minimum wattage with a minimum exposure time and a minimum hole diameter, the laser is an ideal instrument to use on the hairline and crown.     

Viscosity and rheological behavior of castor–canola mixture

In this work, the effects of shear rate on viscosity of selected pure food grade oils (castor and canola) are investigated. The rheological behavior of castor–canola oil mixture is also studied through modeling the experimental data. The effect of shear rate on the variation of viscosity was clearly observed. Interpretations of the results from rheological models indicate that these food grade oils belong to pseudo‐plastic category. The results also show that among the six used mixing rules, Grunberg–Nissan model seems very well fitted to the experimental data.     

Extraction and Enrichment of Triazole and Triazine Pesticides from Honey Using Air‐Assisted Liquid–Liquid Microextraction

In the present work, an easy, fast, and effective approach is developed for the extraction and enrichment of triazole and triazine pesticides in honey by air‐assisted liquid–liquid microextraction coupled with gas chromatography‐flame ionization detection. Initially, honey is dissolved in an acetonitrile: water mixture and after that a few microliter of a less soluble organic solvent in aqueous phase is added. In order to form a cloudy solution, the extractant mixed with aqueous phase is repeatedly sucked and expelled by a syringe needle into a glass tube. After centrifugation, the sedimented phase (1 mL) is removed with a syringe and injected into de‐ionized water. By this action, the settled phase volume is reduced to 10 μL and the analytes are concentrated, too. Under optimum extraction conditions, limits of detection and quantitation for the studied pesticides are in the ranges of 2 to 5 and 6 to 17 ng/g, respectively. Extraction recoveries and enrichment factors are from 61% to 95% and 61 to 95, respectively.     

A block iteration scheme for the solution of systems of equations resulting from linear and nonlinear finite element models

An algorithm combining direct and iterative solution procedures is proposed for the solution of the discrete equations resulting from static or dynamic finite element models. In this technique, the discrete model is broken into regular or irregular blocks of elements. The algorithm is composed of two analysis steps, which are repetitively carried out. In the first step, using the specified boundary data on the block boundaries, the solutions within the blocks are defined directly. In the second step the variables on the block boundaries are updated iteratively. The algorithm would be particularly useful in solving large nonlinear or dynamic problems.     

Electrocatalytic oxidation of ethanol at copper bromide modified copper electrode in comparison to bare and copper chloride modified copper electrodes

Copper bromide modified copper electrode was prepared and used to electrocatalytic oxidation of ethanol. Scanning electron microscopy and energy dispersive x-ray experiments suggested the formation of thin layer of copper bromide on the copper surface. The j₀ for copper bromide modified copper and copper chloride modified copper electrodes are 9.8 and 5.7 folds respectively higher than for that of bare copper electrode. For copper bromide modified copper electrode, the charge transfer coefficient (α) and the number of electrons involved in the rate determining step (n_α) were calculated as 0.44 and 1 respectively.