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1.
The conventional deterministic approach based (DAB) methods are simple and widely used to determine an adequate chain pillar size in coal mines where geological settings, coal characterizations and mining methods have been explored. It is evident that such deterministic methods have some intrinsic limitations in handling uncertainties in material properties, non-regular geometries and different mining operations. In the deterministic stability analysis of a chain pillar, the safety factors as well as all input parameters are deterministic. Although, these parameters generally exhibit uncertainty and should lead to a probabilistic expression for the safety factor. The probabilistic analysis provides a confidence interval to express the reliability of chain pillars stability.In this paper, safety factor is defined as a probabilistic function and the failure probability of designed chain pillar of Tabas coal mine is then evaluated using the First Order Second Moment (FOSM) and the Advanced Second Moment (ASM) methods. The results of the probabilistic stability analysis show that the confidence interval for designed pillars with both mentioned methods applied are similar and their values vary from 84% to 88%. The results of such analyses can be used as a basis for decision-making about the size of chain pillars and reduce the risk of pillars stability as well as the uncertainties. However, a trade-off between cost is essential for making the final decision. 相似文献
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Mohammad Behbahani Fatemeh Najafi Saman Bagheri Majid Kalate Bojdi Parmoon Ghareh Hassanlou Akbar Bagheri 《Environmental monitoring and assessment》2014,186(4):2609-2618
A simple, rapid, and efficient sample pretreatment technique, based on solvent-based de-emulsification dispersive liquid–liquid microextraction (SD-DLLME), followed by high performance liquid chromatography (HPLC) has been developed for simultaneous preconcentration and trace detection of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) in water and urine samples. Some parameters such as acidity of solution, the amount of salt, type, and volume of extraction solvents, type of disperser/de-emulsifier solvent, and its volume were investigated and optimized. Under optimum extraction conditions, the limits of detections (LODs) of this method for MCPA and 2,4-D were 0.2 and 0.6 μg L?1 (based on 3Sb/m) in water and 0.4 and 1.6 μg L?1 in urine, respectively. Furthermore, dynamic linear range of this method for MCPA and 2,4-D was 1–300 and 2–400 μg L?1, repectively. Finally, the applicability of the proposed method was evaluated by extraction and determination of the herbicides in urine and different water samples. 相似文献
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Ramaiah Pushpamala Altalbawy Farag M. A. Margiana Ria Kumar N. Bharath Kahar Fitriani Jalil Abduladheem Turki Komariah Aan Failoc-Rojas Virgilio E. Kadhim Mustafa M. Sivaraman R. Iswanto A. Heri Mustafa Yasser Fakri Najafi Moslem Lari 《Environmental science and pollution research international》2023,30(8):19592-19601
Environmental Science and Pollution Research - Exposure to polycyclic aromatic hydrocarbons (PAHs) during pregnancy has been associated with many adverse child health. However, the evidence on such... 相似文献
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Saeed Kazemi Najafi 《Waste management (New York, N.Y.)》2013,33(9):1898-1905
The use of recycled and waste thermoplastics has been recently considered for producing wood plastic composites (WPCs). They have great potential for WPCs manufacturing according to results of some limited researches. This paper presents a detailed review about some essential properties of waste and recycled plastics, important for WPCs production, and of research published on the effect of recycled plastics on the physical and mechanical properties of WPCs. 相似文献
6.
Mahdavian Seyed Mohammadreza Ahmadpour Borazjani Mahmoud Mohammadi Hamid Asgharipour Mohammad Reza Najafi Alamdarlo Hamed 《Environmental science and pollution research international》2022,29(35):52457-52472
Environmental Science and Pollution Research - Iran’s agricultural production has expanded significantly in recent years. Environmental pollution caused by the use of energy and chemical... 相似文献
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Sorption-desorption of cadmium in aqueous palygorskite, sepiolite, and calcite suspensions: isotherm hysteresis 总被引:2,自引:0,他引:2
Sorption isotherms have been widely used to assess the heavy metal retention characteristics of soil particles. Desorption behavior of the retained metals, however, usually differ from that of sorption, leading to a lack of coincidence in the experimentally obtained sorption and desorption isotherms. In this study, we examine the nonsingularity of cadmium (Cd) sorption–desorption isotherms, to check the possible hysteresis and reversibility phenomena, in aqueous palygorskite, sepiolite and calcite systems. Sorption of Cd was carried out using a 24-h batch equilibration experiment with eight different Cd solution concentrations, equivalent to 20–100% of maximum sorption capacity of each mineral. Immediately after sorption, desorption took place using successive dilution method with five consecutive desorption steps. Both Cd sorption and desorption data were adequately described by Freundlich equation (0.81 < r2 < 0.99). The sorption and desorption reactions, however, did not provide the same isotherms, indicating that hysteresis occurred in Cd sorption–desorption processes. The extent of hysteresis was quantified based on the differences obtained from sorption and desorption isotherms regarding the amount of Cd sorbed, the Freundlich exponent, and the Cd distribution coefficient. The results revealed that, sepiolite possessed the most hysteretic behavior among the minerals studied. Calcite showed much smaller hysteresis compared to the other two silicate clays at low Cd surface load, but its hysteresis indices significantly increased, and exceeded that of palygorskite, as the amount of Cd in the systems increased. The average amount of Cd released after five desorption steps, was 13.8%, 2.2% and 3.6% for the palygorskite, sepiolite and calcite, respectively, indicating that a large portion of Cd was irreversibly retained by the minerals. 相似文献
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Shahbazi Mohammadreza Najafi Mehdi Marji Mohammad Fatehi 《Mitigation and Adaptation Strategies for Global Change》2019,24(3):373-398
Mitigation and Adaptation Strategies for Global Change - Underground coal gasification (UCG) is an energy production pathway in underground coal deposits with the potential advantage of decreasing... 相似文献
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M. Yavarmanesh M. Abbaszadegan A. Alum A. Mortazavi M. B. Habibi Najafi M. R. Bassami M. R. Nassiri 《Food and environmental virology》2013,5(2):103-109
Noroviruses are responsible for approximately 44 % of outbreaks involving dairy products for which causative agents are reported. Recovery of viruses from milk and dairy products is a difficult task. The role of different components of milk in the recovery of viral RNA was evaluated in this study. Four model milk formulations (A–D) were prepared by mixing different combinations of lactose, whey protein, casein, and fat in water. Each model formulation was spiked with five concentrations of bacteriophage MS2. The phenol-guanidine thiocyanate-chloroform protocol was used for extracting viral RNA from the model milk formulations and then extracted RNA was measured by a nanodrop spectrophotometer in ng/μl. The results showed that casein and whey protein had the highest negative impact on RNA yield, especially when the number of MS2 was less than 1.3 pfu/ml. The highest RNA recovery was obtained from the model milk formulation containing all four components; lactose, whey protein, casein, and fat. The amount of extracted RNA was closely correlated with the dry matter content of each formulation and the spiked concentration of coliphage using response surface modeling (R2:0.93). It was determined that milk fat is the most effective component in facilitating RNA extraction and the highest RNA yield can be achieved via elimination of whey protein and casein from milk by centrifugation at 40,000×g for 60 min. To achieve the highest viral RNA recovery efficiency by the proposed method, milk fat must be recombined with the supernatant of the centrifuged sample and then homogenized before performing the extraction protocol. 相似文献
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A novel improved preconcentration method known as rapidly synergistic cloud point extraction (RS-CPE) was established for nickel preconcentration and determination prior to its determination by flame atomic absorption spectrometry. In this work, the traditional CPE pattern was changed and greatly simplified in order to be applicable in metal extraction and detection. This method was accomplished in room temperature in 1 min. Non-ionic surfactant Triton X-114 was used as extractant. Octanol worked as cloud point revulsant and synergic reagent. The various parameters affecting the extraction and preconcentration of nickel such as sample pH, 2,2′-Furildioxime concentration, amounts of octanol, amounts of Triton X-114, type of diluting solvent, extraction time, and ionic strength were investigated and optimized. Under optimal conditions, the calibration curve showed an excellent linearity in the concentration range of 2–200 μg L?1, and the limit of detection was 0.6 μg L?1 for nickel. The developed method was successfully applied for the determination of nickel in food and water samples. The results showed that, the proposed method can be used as a cheap, rapid, and efficient method for the extraction and preconcentration of nickel from real samples. 相似文献