Electrodeposition of lead dioxide on Fe electrode: application to the degradation of Indigo Carmine dye

Journal of Applied Electrochemistry - The modification of an iron electrode was carried out according to the following two steps. In a first step, a cathodic reduction is performed to form a film...     

Natural convection from isothermal flat surfaces

Local heat-transfer coefficients along a flat plate in natural convection in air were measured using Boelter-Schmidt type heat flux meters. Experiments were carried out for different temperature differences in heating and cooling, and with inclinations varying from the horizontal “facing upwards” position, through the vertical position, to the horizontal “facing downwards” position.

The results are presented in terms of local Nusselt number as a function of the local Grashof number “tangential component”. All runs were in the range accepted as that of laminar boundary layer flow. However, under certain conditions when the normal velocity component of the air is directed away from the surface, separated flow is indicated along the trailing part of the surface, well before turbulence sets in in the boundary layer. Separation starts at a certain point along the surface. This point is nearer to the leading edge the higher the temperature difference, and the larger the inclination of the surface to the vertical.

In a separation region, the flux density is uniform. In all other regions the results agreed closely with established theories of laminar boundary layer flow.

A leading adiabatic section, used in some of the experiments, did not affect the results. An appendix gives relations recommended for engineering calculations.     

Analysis and simulation of interrupt overhead impact on OS throughput in high‐speed networks

The paper presents analytical and simulation models to study the impact of interrupt overhead on operating system throughput of network elements such as PC‐based routers, servers, and hosts when subjected to high‐speed network traffic. Under such high network traffic, the system throughput will be negatively affected due to interrupt overhead caused by the incoming traffic. We first present an analytical model for the ideal system when interrupt overhead is ignored. We then present two models which describe the impact of high interrupt rate on system throughput. One model is for employing PIO in which network adapters are not equipped with DMA engines, and the other model is for employing DMA in which network adapters are equipped with DMA engines. The paper also describes detailed discrete‐event simulation models for the ideal system and for systems with DMA and PIO. Simulations results as well as reported experimental measurements show that our analytical models are valid and give a good approximation. Our analysis and simulation work can be valuable in providing insight to understand and predict system behaviour, as well as improving and maintaining good host performance. The paper identifies analytically critical design operation points such as that of overload condition. The paper also proposes solutions and recommendations for improving performance. Copyright © 2005 John Wiley & Sons, Ltd.     

ANN-Based STATCOM Tuning for Performance Enhancement of Combined Wind Farms

Although the wind farms based on squirrel cage induction generators (SCIG) is cheaper than the wind farms based on doubly fed induction generators (DFIG), it is always in desperate need for reactive power compensation. Nevertheless, the wind farms based on DFIG are expensive compared with the SCIG wind farm, it features by its ability to control the active power independent of reactive power. However, combined wind farm (CWF) has been developed to collect the benefits of SCIG and DFIG wind turbines in the same wind farm. In this article, artificial neural network (ANN) is used to evaluate gain parameters of static synchronous compensator (STATCOM) in order to improve the stability performance of CWF. The impact of tuned STATCOM on the performance of CWF during gust wind speed and during three-phase fault is comprehensively investigated. The performance of CWF with STATCOM tuned by ANN is compared with its performance when the STATCOM tuned by the multiobjective genetic algorithm (MOGA) and whale optimization algorithm (WOA). The results show that the performance of CWF can be enhanced using STATCOM tuned by ANN more than MOGA and WOA.     

Arghel Extract: a Promising Green Corrosion Inhibitor

Protection of Metals and Physical Chemistry of Surfaces - The corrosion of copper in an aqueous 0.5 M H2SO4 has been studied under the effect of Arghel plant extracts using potentiodynamic...     

Photocatalytic degradation of methyl orange dye by NiFe<Subscript>2</Subscript>O<Subscript>4</Subscript> nanoparticles under visible irradiation: effect of varying the synthesis temperature

Nanoparticles of nickel ferrites (NiFe₂O₄) were synthesized at different temperature of synthesis (25, 50 and 80 °C) through the chemical co-precipitation method. The synthesized powders were characterized using X-ray diffraction for crystallite size and lattice parameter calculation. It reveals the presence of cubic spinel structure of ferrites with crystallite size between 29 and 41 nm. Transmission electron microscopy and scanning electron microscopy showed uniform distribution of ferrite particles with some agglomeration. The Fourier-transform infrared spectroscopy showed absorption bonds, which were assigned to the vibration of tetrahedral and octahedral complexes. Raman spectroscopy is used to verify that we have synthesized ferrite spinels and determines their phonon modes. The thermal decomposition of the NiFe₂O₄ was investigated by TGA/DTA. The optical study UV–visible is used to calculate the band gap energy. Magnetic measurements of the samples were carried out by means of vibrating sample magnetometer and these studies reveal that the formed nickel ferrite exhibits ferromagnetic behavior. Photoluminescence showed three bands of luminescence located at 420, 440 and 535 nm. The photocatalytic properties of nickel ferrite (NiFe₂O₄) nanoparticles were evaluated by studying the photodecomposition of methyl orange as organic pollutant models and showed a good photocatalytic activity.     

Identification of factors that accelerate hydrogen production by Clostridium butyricum RAK25832 using casamino acids as a nitrogen source

The ability of Clostridium butyricum RAK25832 to use casamino acids as a nitrogen source was investigated. Strain RAK25832 showed the capacity to utilize different types of carbon sources. With glucose as a carbon source (10 g/L), the preferred final concentration of casamino acids was 26.67 g/L, with a cumulative hydrogen production, production rate, and yield of 2505 mL H₂/L, 160 mL/h, and 1.81 mol H₂/mol glucose, respectively. Eighteen metal elements were screened to identify the most important metals for biohydrogen production, and four elements were optimized. The optimal medium composition was MgCl₂·6H₂O (0.1 g/L), K₂HPO₄·3H₂O (6.67 g/L), NaHCO₃ (2.6 g/L), and FeCl₂·4H₂O (0.002 g/L). Vitamin supplementation of the medium showed no significant effect on hydrogen production. Under the optimized conditions, cumulative hydrogen production reached 3074 mL H₂/L. This is the first study to demonstrate the use of casamino acids as a nitrogen source by C. butyricum.     

An enhanced symbiosis organisms search algorithm: an empirical study

Many nature-inspired optimization algorithms have recently been proposed to solve difficult optimization problems where the mathematical gradient-based approaches could not be used. However, those approaches were often not tested on a proper set of problems. Moreover, statistical tests are sometimes not used to validate the conclusions. Therefore, empirical analyses of such approaches are needed. In this paper, a very recent nature-inspired approach, symbiosis organisms search (SOS), is investigated. A set of unbiased and characteristically different problems are used to study the performance of SOS. In addition, a comparison with some recent optimization methods is conducted. Then, the effect of SOS only parameter, eco_size, is studied, and the use of different random distributions is also explored. Finally, three simple SOS variants are proposed and compared to the original SOS. Conclusions are validated using nonparametric statistical tests.

     

Using next generation nuclear power reactors for development of a techno‐economic model for hydrogen production

Nuclear and hydrogen are considered to be the most promising alternatives energy sources in terms of meeting future demand and providing a CO?‐free environment, and interest in the development of more cost‐effective hydrogen production plants is increasing—and nuclear‐powered hydrogen generation plants may be a viable alternative. This paper is a report on investigating the application of new generation nuclear power plants to hydrogen production and development of an associated techno‐economic model. In this paper, theoretical and computational assessments of generations II, III+, and IV nuclear power plants for hydrogen generation scenarios have been reported. Technical analyses were conducted on each reactor type—in terms of the design standard, fuel specification, overnight capital cost, and hydrogen generation. In addition, a theoretical model was developed for calculating various hydrogen generation parameters, and it was then extended to include an economic assessment of nuclear power plant‐based hydrogen generation. The Hydrogen Economic Evaluation Program originally developed by the International Atomic Energy Agency was used for calculating various parameters, including hydrogen production and storage costs, as well as equity, operation and maintenance (O&M), and capital costs. The results from each nuclear reactor type were compared against reactor parameters, and the ideal candidate reactor was identified. The simulation results also verified theoretically proven results. The main objective of the research was to conduct a prequalification assessment for a cogeneration plant, by developing a model that could be used for technical and economic analysis of nuclear hydrogen plant options. It was assessed that high‐temperature gas‐cooled reactors (HTGR‐PM and PBR200) represented the most economical and viable plant options for hydrogen production. This research has helped identify the way forward for the development of a commercially viable, nuclear power‐driven, hydrogen generation plant.