Transmission pricing and recovery of investment costs in the deregulated power system based on optimal circuit prices

Transmission pricing has become a major issue in the discussions about the deregulated electricity markets.Conse-quently,open access to the transmission system is one of the basic topics to allow compe...     

Charge transport mechanism of graphite‐nanosheet‐loaded rubber nanocomposites

Nitrile butadiene rubber loaded with different concentrations of thin graphite nanosheets have been successfully prepared by using a two‐roll mill. The percolation concentration of the nanocomposites was 0.5 phr. The I–V characteristic curves showed that the nanocomposites exhibited ohmic behaviour at a certain voltage and then non‐linear behaviour. The Richardson–Schottky and Poole–Frenkel models were used to investigate the reason for the space charge. The experimental data fit the Schottky model well. The conductivity as a function of temperature was also studied and the data were fitted by using the Mott relation. The Mott relation showed that as the concentration of graphite nanosheets in the rubber composite increases, the hopping distance between the graphite nanosheet layers decreases, which enhances the conductivity of the nanocomposite at low concentrations. Copyright © 2011 Society of Chemical Industry     

Modified Ultrasonic Technique to Study Gd-Doped ZnO Films

Normal ultrasonic transducers of 0.5, 1, and 2 MHz are modified using delay lines which are made of Quartz. Such modification is to ameliorate the capability of the transducer to investigate Gd-doped ZnO thin films whose thickness is too thin. The normal transducers cannot test materials that have too thin thickness due to the near fields of these transducers. The near field is considered as blind area of the transducer. Therefore, the specimen under test must have thickness bigger than the near field of the used transducer, or instead delay lines can be used. Samples of Gd-doped ZnO thin films are prepared using sol gel technique. The ultrasonic pulse echo method is used at room temperature. Flaws are found in different prepared specimens. Results show that such delay lines are suitable to ameliorate the ultrasonic transducer to test Gd-doped ZnO thin films.     

Magnetocaloric Effect in Sr0.4Ba1.6−x La x FeMoO6

Magnetocaloric effect in half-metallic double perovskite Sr_0.4Ba_1.6?x La _x FeMoO₆ (x = 0, 0.1, 0.2, 0.3) were investigated. It is shown that Sr_0.4Ba_1.6?x La _x FeMoO₆ exhibits the largest magnetic entropy change (ΔS _M ) of 0.086 J/kg K upon 0.2 T magnetic field variation. Furthermore, ΔS _M distribution of the Sr_0.4Ba_1.6?x La _x FeMoO₆ is much more uniform than that of gadolinium. Through these results, polycrystalline samples of Sr_0.4Ba_1.6?x La _x FeMoO₆ have some potential applications for magnetic refrigerants in a wide temperature range, including room temperature.     

Experimental investigation on the effect of surface characterization of electrodes on the gas bubble dynamics in electrolyte flow and performance of FLA batteries by using PIV

In the flooded lead_acid batteries (FLAB), gas bubbles are initially formed on the surface of the electrodes, which are produced by electrochemical reactions, and then released into the electrolyte. In the present investigation, the effect of surface characterization of electrodes of FLAB on the gas bubble dynamic parameters in the electrolyte flow at different charging/discharging rates (C-rates) are studied utilizing particle image velocimetry (PIV) method. The results show that the capacity of FLAB have a linear behav-ior due to changes in each of the two parameters of the surface characterization of electrodes and the C-rate. At all State of charges (SOCs) of FLAB cells in different tests, increasing average roughness (Ra) and average wavelength of the roughness (ka) in the electrode surfaces, results in an increase in average bub-ble diameter and bubble rising velocity. Nevertheless, a sharp decrease in the void fraction of bubbles within the electrolyte was observed due to the increment in ka and Ra. Also, the effect of the rising move-ment of gas bubbles within the electrolyte on the average electrolyte velocity pattern in the gap between the electrodes by changing the surface characterization of electrodes are investigated in detail.     

Environmental impact assessment of the Egyptian cement industry based on a life-cycle assessment approach: a comparative study between Egyptian and Swiss plants

Egypt in 2015 announced the alteration of the fuels used in cement plants without the least regard to minimizing the environmental burden (EB) excesses. This study conducts a life-cycle assessment (LCA) of Egyptian cement-manufacturing unit, which is considered as the first one on LCA cement analysis to be conducted in Egypt. This study investigates the LCA of the cement industry in Egypt compared to the Swiss industry, using two methodologies. The first one has been done on-site, surveying the most common types of cement used in the construction industry in Egypt. Meanwhile, SimaPro software has been used to assess the environmental impacts, and three different cement plants were selected for this study: an Egyptian cement plant (ECP) which uses electricity, natural gas, and diesel as energy sources; a Swiss cement plant (SCP) which depends mainly on electricity, natural gas, and coal; and an Egyptian hypothetical plant (EHP) in which electricity and coal are assumed to be the main energy feeds, and comparisons of different strategies including midpoint and endpoint methods are outlined. Regarding the midpoint method, ETP recorded higher respiratory inorganics, aquatic acidification, global warming, and nonrenewable energy impacts than ECP, because of using coal, while for SCP, global warming and respiratory inorganics achieved the highest adverse impacts compared to ECP and EHP—due to the different manufacturing technology used. With regard to the endpoint method, the peak possibility of human health deterioration has been recorded due to the use of coal as fuel. This possibility was reduced by 46 % in the case of SCP as a result of the technology applied, which interestingly represents a reasonable reduction in terms of technological application.     

Energy input–output analysis and application of artificial neural networks for predicting greenhouse basil production

In this study, various Artificial Neural Networks (ANNs) were developed to estimate the production yield of greenhouse basil in Iran. For this purpose, the data collected by random method from 26 greenhouses in the region during four periods of plant cultivation in 2009–2010. The total input energy and energy ratio for basil production were 14,308,998 MJ ha^?1 and 0.02, respectively. The developed ANN was a multilayer perceptron (MLP) with seven neurons in the input layer, one, two and three hidden layer(s) of various numbers of neurons and one neuron (basil yield) in the output layer. The input energies were human labor, diesel fuel, chemical fertilizers, farm yard manure, chemicals, electricity and transportation. Results showed, the ANN model having 7-20-20-1 topology can predict the yield value with higher accuracy. So, this two hidden layer topology was selected as the best model for estimating basil production of regional greenhouses with similar conditions. For the optimal model, the values of the models outputs correlated well with actual outputs, with coefficient of determination (R²) of 0.976. For this configuration, RMSE and MAE values were 0.046 and 0.035, respectively. Sensitivity analysis revealed that chemical fertilizers are the most significant parameter in the basil production.     

Process synthesis and optimization of biorefinery configurations

Recently, there has been a growing interest in the development of cost‐effective technologies for the production of biofuels. A common approach to biofuel research is to invent or improve a biochemical or thermochemical conversion step. Subsequently, other conversion and separation steps are added to form a complete biorefinery flowsheet. Because this approach is structured around a specific conversion step, it may limit the possibilities of configuring optimal and innovative biorefineries. This article proposes a novel and systematic two‐stage approach to the synthesis and optimization of biorefinery configurations, given available feedstocks and desired products. In the synthesis stage, a systems‐based approach is developed to create a methodical way for synthesizing integrated biorefineries. This method is referred to as “forward‐backward” approach. It involves forward synthesis of biomass to possible intermediates and reverse synthesis starting with the desired products and identifying necessary species and pathways leading to them. In the optimization stage, Bellman's principle of optimality is applied to decompose the optimization problem into subproblems in which an optimal policy of available technologies is determined for every conversion step. An optimization formulation is utilized to determine the optimal configuration based on screening and connecting the optimal policies and generating the biorefinery flowsheet. A case study of alcohol‐producing pathways from lignocellulosic biomass is solved to demonstrate the merits of the proposed approach. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

A combined physicochemical and electrocatalytic study of microwave synthesized tungsten mono-carbide nanoparticles on multiwalled carbon nanotubes as a co-catalyst for a proton-exchange membrane fuel cell

Tungsten mono-carbide (WC) nanoparticles supported on multiwalled carbon nanotube (MWCNT) was synthesized by a microwave-assisted solid-state carburization. The prepared samples were used as a co-catalyst to prepare Pt-WC/MWCNT catalyst for a proton-exchange membrane fuel cell. MWCNTs with and without oxidative pretreatments were characterized as the starting precursors. The influence of the carbide formation conditions on the physicochemical characteristics of the final product were extensively investigated. According to the results, surface pretreatment of the MWCNTs can improve the yield of carbide formation. Furthermore, carburization process can improve the catalyst utilization due to increasing the number of surface defects of the MWCNT supporting materials which can be interpreted as structural effect of the carburization process. It is believed that the superior performance of electrodes modified with tungsten carbide is mostly due to the structural effect of the carburization process and synergistic effect between the electrocatalytic activity of WC and Pt.