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Evaluation of TIGGE Ensemble Forecasts of Precipitation in Distinct Climate Regions in Iran

Advances in Atmospheric Sciences 2018年第4期35卷 457-468页

作者： Saleh AMINYAVARI Bahram SAGHAFIAN Majid DELAVAR department of Technical and engineering Science and Research Branch Islamic Azad University department of Water Resources engineering Tarbiat Modares University

The application of numerical weather prediction （NWP） products is increasing dramatically. Existing reports indicate that ensemble predictions have better skill than deterministic forecasts. In this study, numerical ensemble precipitation forecasts in the TIGGE database were evaluated using deterministic, dichotomous （yes/no）, and probabilistic techniques over Iran for the period 2008-16. Thirteen rain gauges spread over eight homogeneous precipitation regimes were selected for evaluation. The Inverse Distance Weighting and Kriging methods were adopted for interpolation of the prediction values, downscaled to the stations at lead times of one to three days. To enhance the forecast quality, NWP values were post-processed via Bayesian Model Averaging. The results showed that ECMWF had better scores than other products. However, products of all centers underestimated precipitation in high precipitation regions while overestimating precipitation in other regions. This points to a systematic bias in forecasts and demands application of bias correction techniques. Based on dichotomous evaluation, NCEP did better at most stations, although all centers overpredicted the number of precipitation events. Compared to those of ECMWF and NCER UKMO yielded higher scores in mountainous regions, but performed poorly at other selected stations. Furthermore, the evaluations showed that all centers had better skill in wet than in dry seasons. The quality of post-processed predictions was better than those of the raw predictions. In conclusion, the accuracy of the NWP predictions made by the selected centers could be classified as medium over Iran, while post-processing of predictions is recommended to improve the quality.

关键词： ensemble forecast NWP TIGGE evaluation post-processing

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Preparation and characterization of Ag^+ ion-exchanged zeolite-Matrimid~5218 mixed matrix membrane for CO_2/CH_4 separation

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Journal of Energy Chemistry 2016年第3期25卷 450-462页

作者： Abtin Ebadi Amooghin Mohammadreza Omidkhah Hamidreza Sanaeepur Ali Kargari Faculty of Chemical engineering Tarbiat Modares University department of Chemical engineering Faculty of Engineering Arak University department of Chemical engineering Amirkabir University of Technology

In this work, the zeolite-Y was ion-exchanged by introducing silver cations into the framework of microsized nano-porous sodium zeolite-Y using a liquid-phase ion exchanged method. The Ag+ion-exchanged zeolite, was then embedded into the Matrimid5218 matrix to form novel mixed matrix membranes(MMMs). The particles and MMMs were characterized by ultraviolet-visible diffuse reflectance spectroscopy(UV–vis DRS), N2adsorption–desorption isotherm, X-ray diffraction(XRD), Fourier transform infrared(FTIR) and scanning electron microscopy(SEM). Furthermore, the effects of filler content(0–20wt%) on pure and mixed gas experiments, feed pressure(2–20 bar) and operating temperature(35–75 oC)on CO2/CH4transport properties of Matrimid/Ag Y MMMs were considered. Characterization results confirmed an appropriate ion-exchange treatment of the zeolites. The SEM results confirmed the superior interfacial adhesion between polymer and zeolites, particularly in the case of Matrimid/Ag Y *** is due to the proper silverous zeolite/Matrimid functional groups’ interactions. The gas permeation results showed that the CO2permeability increased about 123%, from 8.34 Barrer for pure Matrimid to18.62 Barrer for Matrimid/Ag Y(15 wt%). The CO2/CH4selectivity was improved about 66%, from 36.3 for Matrimid to 60.1 for Matrimid/Ag Y(15 wt%). The privileged gas separation performance of Matrimid/Ag Y(15 wt%) was the result of a combined effect of facilitated transport mechanism of Ag+ions as well as the intrinsic surface diffusion mechanism of Y-type zeolite. In order to survey the possibility of using the developed MMMs in industry, the CO2-induced plasticization effect and mixed gas experiment were accomplished. It was deduced that the fabricated MMMs could maintain the superior performance in actual operating conditions.

关键词： AgY zeolite Ion exchange Matrimid,MMMs CO_2/CH_4 selectivity

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Assessment of converting approach to efficient design of micro-turboprop engines

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Chinese Journal of Aeronautics 2020年第2期33卷 572-588页

作者： Hamed GOLCHIN Fathollah OMMI Zoheir SABOOHI department of mechanical engineering Tarbiat Modares UniversityTehran 14115-111Iran Aerospace Research Institute(ARI) Ministry of ScienceResearchand TechnologyTehran 14115-111Iran

The design,manufacture and experiment of a shaft power unit for converting a microturbojet engine to a micro-turboprop in the class of less than 20 kW with the aim of obtaining maximum shaft power were described in this *** this purpose,a Wren 100 micro-turbojet engine was used as the gas generator,and the specifications of its outflow were *** optimal configuration of the inter-stage diffuser,which was an annular S-type diffuser,was selected based on its small total pressure drop and outlet flow *** power turbine was a single stage axial turbine that was designed based on the fixed nozzle angle assumption without any taper or twist in its *** turbine rotor was a bladed disk(Blisk)in which its unique blade profiles were designed based on the Wilson ***,the shaft power unit was completed by designing and manufacturing an exhaust complex and ***,the micro-turboprop engine was tested with an overloading *** results show a significant increase in the extracted power,an acceptable efficiency of the power turbine,and a significant reduction in the Specific Fuel Consumption(SFC)compared to other engines that use similar gas generators.

关键词： Axial turbine Blisk Gas generators Micro-turboprop Power unit

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Polyacrylamide hydrogel application in sand control with compressive strength testing

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Petroleum Science 2019年第1期16卷 94-104页

作者： Mahsa Baghban Salehi Asefe Mousavi Moghadam Samira Zargari MarANDi department of Petroleum engineering Chemistry and Chemical Engineering Research Center of Iran Faculty of Chemical engineering Tarbiat Modares University

Sand production is one of the major problems in sandstone reservoirs. Different mechanical and chemical methods have been proposed to control sand production. In this paper, we propose a chemical method based on using polyacrylamide/chromium triacetate hydrogel to investigate sand production in a synthetic sandpack system. To this end, a series of bulk experiments including the bottle test and rheological analysis along with compression tests were conducted. Experimental results indicated that the compressive strength of the sandpack was increased as much as 30 times by injecting 0.5 pore volume of hydrogel. Also, it was found that the increases in cross-linker and polymer concentrations exhibited a positive impact on the compressive strength of the sandpack, mostly by cross-linker concentration(48 psi). Hydrogel with a higher value of cross-linker could retain its viscoelastic properties against the strain which was a maximum of 122% for 0.5 weight ratio of cross-linker/polymer. The presence of salts, in particular divalent cations, has a detrimental effect on the hydrogel stability. The maximum strain value applied on hydrogel in the presence of CaCl_2 was only about 201% as compared to 1010% in the presence of distilled water. Finally, thermogravimetric analysis and its derivative showed that the hydrogel could retain its structure up to 300 °C. The results of this study revealed the potential application of the hydrogel to control sand production.

关键词： Sand control - Rheology Hydrogel strength Compressive strength Sandpack

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A novel Ga(Ⅲ)coordination complex as an efficient sensitizer for enhancing photocatalytic activity of TiO_(2)/rGO nanocomposite

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Journal of Rare Earths 2023年第7期41卷 1004-1013,I0002页

作者： Amir Hossein Cheshme Khavar Neda Khedri Rubén Rizo Juan Miguel Feliu Martínez Ali Reza Mahjoub Masoumeh Doolabi Ehsan Aghayani department of Chemistry Farhangian UniversityTehranIran department of Chemistry Faculty of Basic SciencesTarbiat Modares UniversityTehranIran Instituto de Electroquímica y Departamento de Química Física Universidad de Alicante03080AlicanteSpain Research Center for Environmental Contaminants Abadan University of Medical SciencesAbadanIran department of Environmental Health engineering Abadan University of Medical SciencesAbadanIran

Narrow solar-light response range and rapid charges recombination are the main technical barriers in TiO_(2) photocatalysis *** overcome these restrictions,in this work we synthesized a novel binuclear gadolinium(Ⅲ) coordination complex,[Gd_(2)(DPDB)_6(DMF)_6(H_(2)O_()2)](DPDB=[(4-dimethylamino)phenyldiazenyl] benzenesulfonate),which was used as an inorganic sensitizer for boosting the visible light-harvesting and quantum efficiency of TiO_(2) supported-reduced graphene oxide(rGO) *** structure of [Gd_(2)(DPDB)_6(DMF)_6(H_(2)O)_(2)](Gd-CMP) was determined from single-crystal X-ray diffraction data,which indicates three-dimensional(3D) supramolecular architecture through hydrogen bonding and CH…π_(ph) *** prepared nanohybrid(Gd-CMP/TG) reveals significantly enhanced visible-light-induced photocatalytic activity for degradation of acetaminophen(ACT).The complete removal of 10 mg/L ACT is achieved over Gd-CMP/TG,and the corresponding rate constant of ACT degradation of nanohybrid is 40-fold higher than that of bare TiO_(2).In prepared ternary nanohybrid,metal-coordination sensitizer(Gd-CMP) acts as an electron donor,and at the same time,rGO serves as an electron acceptor,and the synergistic effect between them efficiently enhances charges separation and inhibits e/h pair recombination in the hybridized *** radical scavenger tests indicate that the photo-induced O_(2)^(-·) radicals dominate ACT *** the basis of the experimental results and calculated energy of electronic levels,a possible mechanism for the improved photocatalytic activity is discussed.

关键词： Gadolinium Coordination complex Sensitizer Photocatalytic Light-harvesting Rare earths

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MRI and PET images fusion based on human retina model

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Journal of Zhejiang university-Science A(Applied Physics & engineering) 2007年第10期8卷 1624-1632页

作者： DANESHVAR Sabalan GHASSEMIAN Hassan department of Electrical and Computer engineering.tarbiat modares university P.O.Box 14115-143 Tehran Iran

The diagnostic potential of brain positron emission tomography (PET) imaging is limited by low spatial resolution. For solving this problem we propose a technique for the fusion of PET and MRI images. This fusion is a trade-off between the spectral information extracted from PET images and the spatial information extracted from high spatial resolution MRI. The proposed method can control this trade-off. To achieve this goal, it is necessary to build a multiscale fusion model, based on the retinal cell photoreceptors model. This paper introduces general prospects of this model, and its application in multispectral medical image fusion. Results showed that the proposed method preserves more spectral features with less spatial distortion. Comparing with hue-intensity-saturation (HIS), discrete wavelet transform (DWT), wavelet-based sharpening and wavelet-à trous transform methods, the best spectral and spatial quality is only achieved simultaneously with the proposed feature-based data fusion method. This method does not require resampling images, which is an advantage over the other methods, and can perform in any aspect ratio between the pixels of MRI and PET images.

关键词：影像融合视网膜多分辨率多分辨率成像正电子发射X射线层析照相术照相术

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Solvent extraction of rubidium from gold waste using conventional SX and new CFE methods

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Rare Metals 2015年第11期34卷 818-828页

作者： Mohammad Reza Tavakoli Mohammadi Seyed Mohammad Javad Koleini Sepideh Javanshir Hossein Abolghasemi Mahmoud Abdollahy Mineral Processing department Tarbiat Modares University Mining engineering department University of Birjand Oil and Gas Center of Excellence School of Chemical Engineering College of Engineering University of Tehran

Solvent extraction（SX） of rubidium（Rb） from leaching filtrate of gold waste（GW） in Mouteh Processing Plant by 18-crown-6（18C6） was studied. High potential of new column flotoextraction（CFE） method in extraction of Rb from dilute solutions was also demonstrated. First, the factors affecting SX of Rb from a synthetic rubidium sulfate solution(containing 100 mg·L-1Rb) were identified.0.05 mol·L-118C6 in kerosene, 0.02 mol·L-1picric acid in aqueous phase, aqueous to organic（A/O） ratio of 1, p H7 and mixing time of 15 min are the optimum values for affective factors. The three-stage precipitation with sodium carbonate, p H adjustment with sulfuric acid and two-stage evaporation and crystallization were conducted to purify the leaching from impurities such as Fe, Al, Mn, Ca and especially competing cations of K and Na. Almost complete extraction of Rb and K from final filtrate containing 0.08 mol·L-1picric acid was performed using 0.2 mol·L-118C6 in kerosene. The Rb and K strippings of 99.12 % and 9.93 %, respectively, are obtained with 2 mol·L-1nitric acid with A/O ratio of 2. Finally, the performance comparison of the CFE and SX methods in similar conditionsshows increased extraction of K and Rb by 16 % and 5 %,respectively, using CFE method.

关键词： Rubidium Gold waste Solvent extraction Column flot

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Estimating Water Retention with Pedotransfer Functions Using Multi-Objective Group Method of Data Handling and ANNs

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Pedosphere 2011年第1期21卷 107-114页

作者： H.BAYAT M.R.NEYSHABOURI K.MOHAMMADI N.NARIMAN-ZADEH department of Soil Science Faculty of AgricultureBu Ali Sina University department of Soil Science Faculty of AgricultureTabriz University department of Irrigation and Drainage engineering Tarbiat Modares University department of mechanical engineering Engineering FacultyGuilan University

Pedotransfer functions(PTFs) have been developed to estimate soil water retention curves(SWRC) by various *** this study PTFs were developed to estimate the parameters(θ s,θ r,α and λ) of the Brooks and Corey model from a data set of 148 *** and aggregate size distribution fractal parameters(PSDFPs and ASDFPs,respectively) were computed from three fractal models for either particle or aggregate size *** most effective model in each group was determined by sensitivity *** with the other variables,the selected fractal parameters were employed to estimate SWRC using multi-objective group method of data handling(mGMDH) and different topologies of artificial neural networks(ANNs).The architecture of ANNs for parametric PTFs was different regarding the type of ANN,output layer transfer functions and the number of hidden *** parameter was estimated using four PTFs by the hierarchical entering of input variables in the *** inclusion of PSDFPs in the list of inputs improved the accuracy and reliability of parametric PTFs with the exception of θ *** textural fraction variables in PTF1 for the estimation of α were replaced with PSDFPs in *** use of ASDFPs as inputs significantly improved α estimates in the *** result highlights the importance of ASDFPs in developing parametric *** mGMDH technique performed significantly better than ANNs in most PTFs.

关键词：人工神经网络土壤水分特征曲线参数估计数据处理多目标保水功能土壤转换函数分形模型

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Numerical assessment of the mechanical stability in vertical,directional and horizontal wellbores

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International Journal of Mining Science and Technology 2013年第6期23卷 937-942页

作者： Kamran Goshtasbi Ayub Elyasi Ali Naeimipour department of Mining engineering Tarbiat Modares University School of Energy and Mineral engineering Pennsylvania State University

In this research the stability of wellbore is evaluated in seven different stress regimes and diverse orientations using FLAC3D *** normalized yielded zone area(NYZA.i.e.,the ratio of surrounding yielded cross-sectional area to initial area of wellbore)is determined for different mud pressures as well as diverse orientations of *** means of MATLAB software the best curve is fitted to the recorded points and then the optimized mud pressure is calculated using these *** optimized orientation is selected considering these *** the mud pressure resulted from this method was compared with the mud pressure obtained from the Mogi-Coulomb criterion and then with the fields *** minimum allowable mud pressure obtained from the NYZA criterion is close to actual data and the value obtained from the Mogi-Coulomb ***,the NYZA is considered to be an appropriate criterion for wellbore stability analysis.

关键词： NYZA Mud pressure Optimum orientation Stress regime

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A New Peer-to-Peer Topology for Video Streaming Based on Complex Network Theory

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Journal of Systems Science & Complexity 2015年第1期28卷 16-29页

作者： MARZA Venus DEHGHAN Mehdi AKBARI Behzad department of Computer engineering Science and Research BranchIslamic Azad University department of Computer engineering and Information Technology Amirkabir University of Technology department of Electrical and Computer engineering Tarbiat Modares University

A new wave of networks labeled Peer-to-Peer(P2P) networks attracts more researchers and rapidly becomes one of the most popular *** order to matching P2 P logical overlay network with physical topology,the position-based topology has been *** proposed topology not only focuses on non-functional characteristics such as scalability,reliability,fault-tolerance,selforganization,decentralization and fairness,but also functional characteristics are addressed as *** experimental results show that the hybrid complex topology achieves better characteristics than other complex networks' models like small-world and scale-free models;since most of the real-life networks are both scale-free and small-world networks,it may perform well in mimicking the ***,it reveals that the authors improve average distance,diameter and clustering coefficient versus Chord and CAN ***,the authors show that the proposed topology is the most robust model,against failures and attacks for nodes and edges,versus small-world and scale-free networks.

关键词：复杂网络理论物理拓扑对等网络视频流小世界网络无标度网络拓扑结构功能特性

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