Ehya F.,Islamic Azad University at Behbahan |
Mazraei S.M.,Islamic Azad University at Behbahan
Journal of African Earth Sciences | Year: 2017
Barite mineralization occurs at Chenarvardeh deposit as layers and lenses in Upper Eocene volcanic and pyroclastic rocks. The host rocks are intensely saussuritized in most places. Barite is accompanied by calcite, Mn-oxides, galena and malachite as subordinate minerals. The amount of Sr in barites is low and varies between 0.11 and 0.30 wt%. The concentration of Rb, Zr, Y, Ta and Hf is also low (<5 ppm) in barite samples. The amount of total REEs (∑REE) is low in barites, ranging from 7.51 to 30.50 ppm. Chondrite-normalized REE patterns reveal LREE enrichment with respect to HREE, and positive Ce anomalies. Fluid inclusions are common in barite samples, being dominantly from liquid-rich two phase (L + V) type. Salinity values in fluid inclusions range from 9.41 to 18.69 wt% NaCl equivalent with most frequent salinities falling in the range of 10–15 wt% NaCl equivalent. Homogenization temperatures (Th) range between 160 and 220 °C, being the 180–200 °C range as the most common Th interval. A combination of factors, including geologic setting, host rock, mineral assemblages, REE geochemistry and fluid inclusion data are consistent with a submarine volcanic hydrothermal model for barite formation at the Chenarvardeh deposit. Mineral-forming fluids originated from solutions related to submarine hydrothermal activities deposited barite on seafloor as they encountered sulfate-bearing seawater. © 2016
Shamoushaki M.,Islamic Azad University at Tehran |
Ehyaei M.A.,Islamic Azad University |
Ghanatir F.,Islamic Azad University at Behbahan
Energy | Year: 2017
Thermodynamic, exergy, economic and environmental analysis of a solid oxide fuel cell and gas turbine hybrid cycle have been done in this paper. Also, multi-objective optimization of this cycle has been done by NSGA-II algorithm. In order to defining of the optimum design point, interactive fuzzy multi-objective method has been used. At optimum point, the cost function value, 0.0435 (US$/s) and exergy efficiency approximately 57.7% have been obtained. As well, sensitivity analysis of fuel cost per energy unit into objective functions has been done. In addition, rising inlet temperature of gas turbine from 900 up to 1600 (K), has caused an increase in output power up to 8.5% and entropy generation about 30% and a reduction in exergy efficiency from 61.9% to 51.7%. By evaluation of entropy generation rate, it has been concluded that most of enthalpy generation rate (32%) is related to combustion chamber. Increasing of fuel cell stack temperature causes an increase in exergy efficiency from 56.6% up to 60.2% and about 34.8% in output power of the cycle and a reduction in exergy efficiency from 62.8% to 59.1% and 8.4% in fuel cell power. Also, payback time of this cycle is about 3.12 years. © 2017 Elsevier Ltd
Ehya F.,Islamic Azad University at Behbahan |
Lotfi M.,Geological Survey of Iran |
Rasa I.,Shahid Beheshti University
Journal of Asian Earth Sciences | Year: 2010
The Emarat deposit, with a total proved reserve of 10 Mt ore grading 6% Zn and 2.26% Pb, is one of the largest Zn-Pb deposits in the Malayer-Esfahan belt. The mineralization is stratabound and restricted to Early Cretaceous limestones and dolomites. The ore consists mainly of sphalerite and galena with small amounts of pyrite, chalcopyrite, calcite, quartz, and dolomite. Textural evidence shows that the ore has replaced the host rocks and thus is epigenetic. Sulfur isotopes indicate that the sulfur in sphalerite and galena has been derived from Cretaceous seawater through thermochemical sulfate reduction. Sulfur isotope compositions of four apparently coprecipitated sphalerite-galena pairs suggest their precipitation was under equilibrium conditions. The sulfur isotopic fractionation observed for the sphalerite-galena pairs corresponds to formation temperatures between 77 °C and 168 °C, which agree with homogenization temperatures of fluid inclusions. Lead-isotope studies indicate that the lead in galena has been derived from heterogeneous sources including orogenic and crustal reservoirs with high 238U/204Pb and 232Th/204Pb ratios. Ages derived from the Pb-isotope model give meaningless ages, ranging from Early Carboniferous to future. It is probable that the Pb-isotope model ages that point to an earlier origin than the Early Cretaceous host rocks are derived from older reservoirs in the underlying Carboniferous or Jurassic units, either from the host rocks or from earlier-formed ore deposits within these units. This research and other available data show that the Emarat Zn-Pb deposit has many important features of Mississippi Valley-type (MVT) lead-zinc deposits and thus we argue that it is an MVT-type ore deposit. © 2009 Elsevier Ltd. All rights reserved.
Askari M.,Behbahan Higher Educational Complex |
Taghizadeh M.,Islamic Azad University at Behbahan
European Journal of Scientific Research | Year: 2011
One of the emerging technologies that being investigated as an alternative to CMOS VLSI is Quantum-Dot Cellular Automata (QCA). Its advantages such as faster speed, smaller size, and lower energy consumption are very good-looking. Unlike conventional digital circuits in which information is transferred using electrical current, QCA transfers information by propagate a polarization state. This paper proposes a detailed design analysis of combinational and sequential logic circuits for quantum-dot cellular automata. The aim is to maximize the circuit density and focus on a layout that is minimal in its use of cells.
Fetanat A.,Islamic Azad University at Behbahan |
Shafipour G.,Islamic Azad University at Behbahan
Expert Systems with Applications | Year: 2011
In this paper, we present a formulation that enables Ant Colony Optimization for Continuous Domains (ACOR) to seek the optimal solution of the unit maintenance scheduling problem. ACOR is a direct extension of Ant Colony Optimization (ACO). Also it is the significant ant-based algorithm for continuous optimization. For the maintenance scheduling, cost reduction is as important as reliability. The objective function of this algorithm considers the effect of economy as well as reliability. Various constraints such as spinning reserve, duration of maintenance crew are being taken into account. The ACOR formulation developed is applied on a power system with six generating units. The simulation result of this technique is compared with those reported in literature. The outcome is very encouraging and proves that the authors' proposed approach outperforms them in terms of reaching a better optimal solution and speed. © 2011 Published by Elsevier Ltd.
Ehya F.,Islamic Azad University at Behbahan
Journal of Geochemical Exploration | Year: 2012
Fluorite vein mineralization occurs mainly in slates and phyllites of Lower Jurassic Shemshak Formation and scarcely in Triassic limestones in Bozijan, which is situated at the west of Mahallat city in the Markazi Province of Iran. The ore consists mainly of fluorite, quartz, calcite, and iron oxides. The subordinate components are galena, pyrite, manganese oxides, and malachite. Local wall-rock alterations include argilization and silicification. The nature of the mineralization and ore-host rock relationships indicate an epigenetic mode of formation for fluorite mineralization. Fluid inclusions in early fluorites and quartz consist of aqueous and aqueous-carbonic inclusions, thereby showing that during deposition of bulk fluorites, two immiscible fluids are involved: aqueous and carbonic. The aqueous fluid is a mixture of two low- and high-salinity (<15 and >26.24wt.% NaCl equivalent) H 2O-NaCl-(CaCl 2-KCl-MgCl 2) brines, as is evidenced by T h-salinity plots. The aqueous inclusions are homogenized at temperatures between 152.5 and 312°C. The aqueous-carbonic inclusions exhibit salinity and homogenization temperature in ranges between 22.04 and 24.26wt.% NaCl equivalent and between 253 and 390.5°C, respectively. Fluid inclusions in late fluorites show the fluorites were precipitated from a colder (102.4-175°C) and less saline (15.96-24.45wt.% NaCl equivalent) fluid than the early fluorites. Rare earth element (REE) analysis in fluorites revealed extremely low values in ranges between 2.87 and 34.39. ppm for early fluorites and between 1.91 and 6.4. ppm for late fluorites, thus indicating that fluorites had been derived from a sedimentary environment. However, Tb/Ca and Y/Ho ratios invariably suggest a hydrothermal origin for Bozijan fluorites. The Ce/Yb ratios and chondrite-normalized patterns revealed that the fluorites (early as well as late ones) are enriched in LREE (light rare earth element) relative to HREE (heavy rare earth element). This indicates that REE leaching from source rocks and fluid migration occurred under high-temperature and low-pH conditions. The enigmatic LREE-enriched late fluorites suggest that deposition of fluorites in Bozijan did not occur during a long-lived episode of mineralization. Europium represents positive as well as negative anomalies that have been probably caused by fluorite precipitation from mixing two fluids possessing opposite Eu anomalies. The Ce/Ce * ratios portray persistent negative Ce anomalies, thus indicating reducing conditions in the hydrothermal fluids. In the (La/Yb)n-Eu/Eu * diagram, data points do not overlap with the fields represented by fluorite-bearing Au-Ag deposits from elsewhere, thus indicating a very low potential for precious-metal mineralization in the studied area. This interpretation is well in line with the low contents of precious metals in the Bozijan deposit, thus suggesting that REE geochemistry is a reliable tool for exploring precious metals in fluorite deposits. The Bozijan deposit is classified here as an "unconformity-related fluorite deposit." According to a conceptual model, mineralization occurred when the ascending hypersaline brines mixed with the less saline connate fluids in sediments of Triassic and predominantly Jurassic ages. The less saline connate brines were assumed to be the fluoride-bearing solutions, as suggested by the high F contents of the rocks containing them and REE patterns. © 2011 Elsevier B.V.
Ehya F.,Islamic Azad University at Behbahan
Mineralogy and Petrology | Year: 2012
The Bijgan barite deposit, which is located northeast of Delijan in Markazi Province of Iran, occurs as a small lenticular body at the uppermost part of an Eocene volcano-sedimentary rock unit. The presence of fossiliferous and carbonaceous strata suggests that the host rocks were deposited in a quiet marine sedimentary environment. Barite, calcite, iron oxides and carbonaceous clay materials are found as massive patches as well as thin layers in the deposit. Barite is marked by very low concentrations of Sr (1-2%) and total amounts of rare earth elements (REEs) (6.25-17.39 ppm). Chondrite-normalized REE patterns of barite indicate a fractionation of light REEs (LREEs) from La to Sm, similar to those for barite of different origins from elsewhere. The La CN/Lu CN ratios and chondrite-normalized REE patterns reveal that barite in the Bijgan deposit is enriched in LREE relative to heavy rare earth elements (HREEs). The similarity between the Ce/La ratios in the barite samples and those found in deep-sea barite supports a marine origin for barite. Lanthanum and Gd exhibit positive anomalies, which are common features of marine chemical sediments. Cerium shows a negative anomaly in most samples that was inherited from the negative Ce anomaly of hydrothermal fluid that mixed with seawater at the time of barite precipitation. The δ 18O values of barites show a narrow range of 9.1-11.4‰, which is close to or slightly lower than that of contemporaneous seawater at the end of the Eocene. This suggests a contribution of oxygen from seawater in the barite-forming solution. The δ 34S values of barites (9. 5-15. 3‰) are lower than that of contemporaneous seawater, which suggests a contribution of magmatic sulfur to the ore-forming solution. The oxygen and sulfur isotope ratios indicate that submarine hydrothermal vent fluids are a good analog for solutions that precipitated barite, due to similarities in the isotopic composition of the sulfates. The available data including tectonic setting, host rock characteristics, REE geochemistry, and oxygen and sulfur isotopic compositions support a submarine hydrothermal origin for the Bijgan barite deposit. At the seafloor, barite deposition occurred where ascending Ba-bearing hydrothermal fluids encountered seawater. Sulfate was derived from the sulfate-bearing marine waters, and, to a lesser extent, by oxidized H 2S, which was derived from magmatic hydrothermal fluids. © 2011 Springer-Verlag.
Ehya F.,Islamic Azad University at Behbahan
Mineralogy and Petrology | Year: 2014
Lead and zinc mineralization occurs in dolostones of the Middle Devonian Sibzar Formation at Ozbak-Kuh, which is located 150 km north of Tabas city in East Central Iran. The ore is composed of galena, sphalerite and calcite, with subordinate dolomite and bitumen. Wall-rock alterations include carbonate recrystallization and dolomitization. Microscopic studies reveal that the host rock is replaced by galena and sphalerite. The Pb-Zn mineralization is epigenetic and stratabound. The δ13C values of hydrothermal calcite samples fall in the narrow range between -0.3‰ and 0.8‰. The δ18O values in calcite display a wider range, between -14.5‰ and -11.9‰. The δ13C and δ18O values overlap with the oxygen and carbon isotopic compositions of Paleozoic seawater, indicating the possible important participation of Paleozoic seawater in the ore-forming fluid. The δ18O signature corresponds to a spread in temperature of about 70 °C in the ore-bearing fluid. The δ13C values indicate that the organic materials within the host rocks did not contribute significantly in the hydrothermal fluid. The δ34S values of galena and sphalerite samples occupy the ranges of 12.2‰-16.0‰ and 12.1-16.8‰, respectively. These values reveal that the seawater sulfate is the most probable source of sulfur. The reduced sulfur was most likely supplied through thermochemical sulfate reduction. The sulfur isotope ratios of co-precipitated sphalerite-galena pairs suggest that deposition of the sulfide minerals took place under chemical disequilibrium conditions. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of the galena samples represent average values of 18.08, 15.66, and 38.50, respectively. These ratios indicate that galena Pb likely originated from an orogenic source in which supracrustal rocks with high 238U/204Pb and 232Th/204Pb ratios are dominant. The average lead isotope model age portrays Cambrian age. This model age is not coeval with the host rocks, which are of middle Devonian age. It is probable that the pre-Middle Devonian model age shows the derivation of Pb from older sources either from host rocks of Cambrian age or from deposits previously formed in these rock units. The Pb isotopic composition of galena accords with the occurrence of an orogenic activity from Late Neoproterozoic to Lower Cambrian in Central Iran. The proposed genetic model considers the fact that mineralization formed in fractured and brecciated host rocks along shear zones and faults from metal-bearing connate waters that were discharged due to deformational dewatering of sediments. © 2013 Springer-Verlag Wien.
Hajabdollahi F.,Islamic Azad University at Behbahan |
Hajabdollahi Z.,Islamic Azad University at Behbahan |
Hajabdollahi H.,Islamic Azad University at Behbahan
Applied Soft Computing Journal | Year: 2012
In this paper a steam turbine power plant is thermo-economically modeled and optimized. For this purpose, the data for actual running power plant are used for modeling, verifying the results and optimization. Turbine inlet temperature, boiler pressure, turbines extraction pressures, turbines and pumps isentropic efficiency, reheat pressure as well as condenser pressure are selected as fifteen design variables. Then, the fast and elitist Non-dominated Sorting Genetic Algorithm (NSGA-II) is applied to maximize the thermal efficiency and minimize the total cost rate (sum of investment cost, fuel cost, and maintenance cost) simultaneously. The results of the optimal design are a set of multiple optimum solutions, called 'Pareto optimal solutions'. The optimization results in some points show 3.76% increase in efficiency and 3.84% decrease in total cost rate simultaneously, when it compared with the actual data of the running power plant. Finally as a short cut to choose the system optimal design parameters a correlation between two objectives and fifteen decision variables with acceptable precision are presented using Artificial Neural Network (ANN). © 2012 Elsevier B.V. All rights reserved.
Khorasaninejad E.,Islamic Azad University at Behbahan |
Hajabdollahi H.,Vali e Asr University of Rafsanjan
Energy | Year: 2014
In this paper, a solar assisted heat pump is modelled and optimized. Solar panel surface areas, evaporator pressure, condenser pressure, capacity of heat storage tank as well as the value of superheating/subcooling in evaporator/condenser are selected as design parameters. MOPSO (Multi-objective Particle Swarm Optimization) algorithm is used to find the optimum value of design parameters where TAC (total annual cost) and COP (coefficient of performance) taken as two objective functions. TAC is included with sum of investment, operation and environmental costs. The optimization is separately performed for five working fluids including R123, R134a, R245fa, R407C and R22. The optimization results showed that the best studied working fluid is R245fa in both thermo-economical and environmental view point with 1746.1 ·/year as TAC, 3.76 for COP and annual environmental cost of 81.825. The optimum results of R245fa as working fluid, showed 15.22%, 21.28%, 22.31% and 44.66% improvement in TAC compared with R134a, R123, R22 and R407C, respectively. Furthermore, COP improvement for R245fa was obtained 26.77%, 30.92%, 34.31% and 48.12% compared with R134a, R123, R22 and R407C, respectively. © 2014 Elsevier Ltd.