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Input data modeling is a critical component of a successful simulation application. A perspective of the area is given with an emphasis on available probability distributions as models, estimation methods, model selection and discrimination, and goodness of fit. Three specific distribution classes (lambda,S
B
, TES processes) are discussed in some detail to illustrate characteristics that favor input models. Regarding estimation, we argue for maximum likelihood estimation over method of moments and other matching schemes due to intrinsic superior properties (presuming a specific model) and the capability of accommodating messy data types. We conclude with a list of specific research problems and areas warranting additional attention. 相似文献
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Calcium aluminate (12CaO–7Al2O3) powder was synthesized using three methods, viz. Pechini, coprecipitation, and a new novel facile decomposition route starting from activated alumina and calcium nitrate precursors, then used as a support to prepare a series of 31 wt%Ni/12CaO–7Al2O3 catalysts by deposition–precipitation method. The resultant catalysts were tested in steam pre-reforming of natural gas at 400–550 °C, low steam-to-carbon (S/C) molar ratio of 1.5, and atmospheric pressure. The obtained samples were characterized by Brunauer–Emmett–Teller (BET) analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), hydrogen chemisorption, and CO2–temperature-programmed desorption (TPD). Experimental results showed that the basicity and morphology of the supports depended significantly on the synthesis method. Calcium aluminate synthesized using the new decomposition procedure showed surface area of 6.23 m2 g?1, while the surface area of those prepared by the Pechini and coprecipitation method were 1.38 and 3.76 m2 g?1, respectively. The catalytic properties of the 31 wt%Ni/12CaO–7Al2O3 catalysts were strongly influenced by the support preparation approach. The highest specific surface area (about 230 m2 g?1), smallest Ni particle size (8.86 nm), and highest nickel dispersion (7.48%) were observed for the catalyst whose support was synthesized by the decomposition method. Even at high gas hourly space velocity (GHSV) of 2 × 105 mL \({\text{g}}^{ - 1}_{\text{catalyst}}\) h?1, this catalyst exhibited around 100% C2H6 and C3H8 conversion at temperature above 500 °C. High catalytic stability during 60 h time on-stream was also shown. The TPO profiles of the spent catalyst demonstrated high resistance to carbon formation. 相似文献
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Hossein Imanieh Mansooreh Sarlak Tayebeh Amanpour Ayoob Bazgir 《Helvetica chimica acta》2013,96(10):1978-1982
An efficient method for the diastereoselective synthesis of chromane‐3,4‐dicarboxamides via the three‐component reaction of 2‐oxo‐2H‐chromene‐3‐carboxylic acids, amines, and isocyanides in MeCN is reported. 相似文献
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Research on Chemical Intermediates - Iron-nanoparticle-impregnated activated carbon (IrAC) nanocomposite was synthesized as a new vanadium adsorbent. The vanadium adsorption rate for commercial... 相似文献
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Hakimeh Sharififard Mansooreh Soleimani Francesco Pepe 《Research on Chemical Intermediates》2017,43(4):2253-2272
In this work, iron nanoparticles were impregnated onto a commercial activated carbon surface to produce a novel adsorbent called iron-activated carbon nanocomposite (I-AC). Commercial activated carbon (CAC) and I-AC were used for vanadium separation in a fixed-bed column. The effects of various operating parameters such as inlet vanadium ion concentration, adsorbent dose and volumetric flow rate on vanadium separation performance of CAC were investigated. The performance of both adsorbents was compared in three adsorption/desorption cycles. The experimental breakthrough curves of vanadium ions in the fixed-bed column were modeled using the film-pore-surface diffusion model (FPSDM). The four mass transfer parameters characterizing this model, namely the external mass-transfer coefficient (k f ), pore and surface diffusion coefficients (D p and D s ), and axial dispersion coefficient (D L ) were evaluated through the model. Modelling and experimental results showed that the I-AC nanocomposite has a better performance for vanadium separation in comparison to AC. Sensitivity analysis on the FPSDM showed that the pore and surface diffusion, external mass transfer and axial dispersion play a significant role in vanadium separation using the I-AC. On the other hand, surface diffusion resulted to be relatively less important when CAC was used. 相似文献
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Meisam Shabanian Khalil Faghihi Ahmad Raeisi Mansooreh Varvanifarahani Hossein Ali Khonakdar Udo Wagenknecht 《Journal of Thermal Analysis and Calorimetry》2014,117(1):293-299
New polyimide (PI) nanocomposites containing two different amounts of MWCNT (PI/MWCNT) were prepared via in situ polymerization technique. Transmission electron microscopy showed that MWCNT was exfoliated in the polymer matrix, resulting in well-dispersed morphologies at 1 and 3 mass% MWCNT contents. The effects of multiwalled carbon nanotubes (MWCNT) on the thermal and flammability properties of new PI derived from 1,3-bis[4,4′-aminophenoxy]propane and biphenyl dianhydride were investigated by thermogravimetric analysis (TG) in nitrogen and air atmosphere, differential scanning calorimetry, and microscale combustion calorimeter (MCC). The PI/MWCNT nanocomposites were electrically conductive with maximum conductivity obtained at 3 mass% MWCNT, which is favorable for many potential applications. TG results showed that the addition of MWCNT resulted in a substantial increase of the thermal stability and char yields of the nanocomposites compared to those of the neat PI. Flame retardancy of the nanocomposites was significantly improved in the presence of MWCNT. 相似文献
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A Kaylani M Mollaghasemi D Cope S Fayez G Rabadi M Steele 《The Journal of the Operational Research Society》2008,59(10):1312-1320
Several NASA programs have been established to study and improve the current launch capability to meet the need for more aggressive space exploration in the future. Numerous launch systems have been proposed by different government and commercial organizations with the potential goal of replacing the Space Shuttle. NASA must evaluate new designs and technologies with the objective of improving upon today's Shuttle cost, performance, and turnaround time, before the government or commercial organizations pursue the large undertaking of a new launch system. To address this issue, the Generic Simulation Environment for Modelling Future Launch Operations (GEM-FLO) was developed to accurately predict processing turnaround times and other effectiveness criteria and support making key business and program decisions. GEM-FLO utilizes a generic modelling paradigm to provide a single platform for modelling different designs, which helped significantly cut the cost of these studies. This paper documents a success story in generic simulation modelling. 相似文献
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