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On the dynamically formed oxide films in molten Mg

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Journal of Magnesium and Alloys 2020年第1期8卷 219-230页

作者： Mohammad Mahdi Jalilvand mehdi Akbarifar mehdi Divandari Hassan Saghafian School of Metallurgy and Materials Engineering Iran University of Science and Technology(IUST)NarmakTehran16846-13114Iran

The so-called“Oxide/Metal/Oxide sandwich”method is one of the technique used to investigate the dynamic oxidation of metals which happens during the casting *** this study,characteristics of the oxide films formed on the molten magnesium in dynamic conditions have been investigated using the aforementioned *** air bubbles were released into the cast sample at the pressure of 0.2 atm through a quartz tube of 1 mm internal *** interface of two adjacent entrapped bubbles is considered as the Oxide/Metal/Oxide(OMO)*** sandwiches were characterized by the aid of the optical and scanning electron microscopy and also X-Ray diffraction *** different approaches,including measuring the width of the folds formed on the oxide films and the edge of the sandwiches,were used to estimate the thickness of the *** thicknesses were estimated to be in the range of 200 to 800 *** features such as fold,wrinkle,and crack were observed on the OMO *** the microscopic scale,the oxide films were rough and *** is attributed to the non-protective behavior of oxide *** XRD patterns indicated that the oxide films formed on the pure molten magnesium in dynamic conditions are crystallized MgO.

关键词： Dynamic oxidation Bifilm Magnesium Oxide films Casting defects

HALOMETHYLATION OF POLYSTYRENE AND SUBSEQUENT PYRIDINATION VIA A HOMOLYTIC PATHWAY

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Chinese Journal of Polymer Science 2006年第6期24卷 627-635页

作者： Sad Moulay Nadia mehdi Laboratoire de Chimie-Physique Moléculaire et Macromoléculaire Faculté des Sciences de l'Ingénieur Departement de Chimie IndustrielleUniversité de BlidaRoute de SoumaB. P. 270Blida 09000Algeria

Chloromethylation of polystyrene （PS） with two different chloromethylating systems methylal/thionyl chloride and paraformaldehyde/trimethylchlorosilane was studied. Soluble chloromethylated polystyrene with a degree of substitution of 89% was obtained. The Conant-Finkelstein reaction on the chloromethylated PS afforded soluble iodomethylated polystyrene with a degree of substitution as high as 96%. The reaction conditions of Minisci were employed to radically pyridinate PS via its iodomethylated derivative. Polyelectrolytes were formed which could be converted to normal polymers by treatment with a 20% aqueous solution of NaOH.

关键词： Chloromethylated polystyrene Conditions of Minisci Iodomethylated polystyrene Pyridinated polystyrene.

Modeling flame propagation speed and quenching distance of aluminum dust flame with spatially random distribution of particles

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Journal of Central South University 2017年第1期24卷 81-89页

作者： mehdi Bidabadi Alireza Khoeini Poorfar Combustion Research Laboratory School of Mechanical EngineeringIran University of Science and Technology(IUST)Narmak16846-13114TehranIran

In this research combustion of aluminum dust particles in a quiescent medium with spatially discrete sources distributed in a random way was studied by a numerical approach.A new thermal model was generated to estimate flame propagation speed in a lean/rich reaction *** speed for different particle diameters and the effects of various oxidizers such as carbon dioxide and oxygen on flame speed were *** was considered the inert *** addition,the quenching distance and the minimum ignition energy(MIE) were studied as a function of dust *** burning time models for aluminum were employed and their results were compared with each *** model was based on conduction heat transfer mechanism using the heat point source *** combustion of single-particle was first studied and the solution was *** the dust combustion was investigated using the superposition principle to include the effects of surrounding *** is found that larger particles have higher values of quenching distance in comparison with smaller particles in an assumed dust *** the increase of dust concentration the value of MIE would be decreased for an assumed particle *** random discrete heat sources method,the obtained results of random distribution of fuel particles in space provide closer and realistic predictions of the combustion physics of aluminum dust flame as compared with the experimental findings.

关键词： flame propagation speed random particle distribution quenching distance random discrete combustion aluminum

An Efficient Two-Phase Model for Computing Influential Nodes in Social Networks Using Social Actions

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Journal of Computer Science & Technology 2018年第2期33卷 286-304页

作者： mehdi Azaouzi Lotfi Ben Romdhane Modeling of Automated Reasoning Systems Research Laboratory LR17ES05 Higher Institute of Computer Science and Telecom University of Sousse Sousse 526-~002 Tunisia

The measurement of influence in social networks has received a lot of attention in the data mining community. Influence maximization refers to the process of finding influential users who make the most of information or product adoption. In real settings, the influence of a user in a social network can be modeled by the set of actions （e.g., ＂like＂, ＂share＂, ＂retweet＂, ＂comment＂） performed by other users of the network on his/her publications. To the best of our knowledge, all proposed models in the literature treat these actions equally. However, it is obvious that a ＂like＂ of a publication means less influence than a ＂share＂ of the same publication. This suggests that each action has its own level of influence （or importance）. In this paper, we propose a model （called Social Action-Based Influence Maximization Model, SAIM） for influence maximization in social networks. In SAIM, actions are not considered equally in measuring the ＂influence power＂ of an individual, and it is composed of two major steps. In the first step, we compute the influence power of each individual in the social network. This influence power is computed from user actions using PageRank. At the end of this step, we get a weighted social network in which each node is labeled by its influence power. In the second step of SAIM, we compute an optimal set of influential nodes using a new concept named ＂influence-BFS tree＂. Experiments conducted on large-scale real-world and synthetic social networks reveal the good performance of our model SAIM in computing, in acceptable time scales, a minimal set of influential nodes allowing the maximum spreading of information.

关键词： social network social influence social action personalized PageRank influence-BFS tree

Therapeutic role of yoga in neuropsychological disorders

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World Journal of Psychiatry 2021年第10期11卷 754-773页

作者： Elnaz Nourollahimoghadam Shaghayegh Gorji Ali Gorji Maryam khaleghi Ghadiri Shefa Neuroscience Research Center Khatam Alanbia HospitalTehran ***Iran Epilepsy Research Center Munster UniversityMunster 48149Germany Department of Neuroscience Mashhad University of Medical SciencesMashhad ***Iran epartment of Neurosurgery Munster UniversityMunster 48149Germany

Yoga is considered a widely-used approach for health conservation and can be adopted as a treatment modality for a plethora of medical conditions,including neurological and psychological ***,we reviewed relevant articles entailing various neurological and psychological disorders and gathered data on how yoga exerts positive impacts on patients with a diverse range of disorders,including its modulatory effects on brain bioelectrical activities,neurotransmitters,and synaptic *** role of yoga practice as an element of the treatment of several neuropsychological diseases was evaluated based on these findings.

关键词： Complementary medicine,depression Bipolar disorder Schizophrenia Anxiety Migraine Parkinson’s disease Alzheimer’s disease Epilepsy Multiple sclerosis

Electrophoretic deposition and an investigation of co-dopants effect on luminescence property of Mg2SiO4:Eu3+phosphors

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Journal of Rare Earths 2017年第12期35卷 1171-1179页

作者： mehdi Ghahari Ali Reza Naeimi Department of Nanomaterials and Nano Coatings Institute for Color Science and TechnologyTehranIran

Forsterite particles doped with europium ions（Eu^（3＋）） were synthesized via a solution combustion method. The effect of co-dopants on photoluminescence intensity was described. Different percentages of calcium（Ca^（2＋））, zinc（Zn^（2＋））, barium（Ba^（2＋）） and strontium（Sr^（2＋）） were added to the Mg2SiO4：Eu^（3＋）*** synthesized sample was characterized by X-ray diffraction, transmission electron microscopy,scanning electron microscopy, spectrofluorometer and the FTIR spectroscopy. X-ray diffraction（XRD）results revealed that dominant phase was forsterite in all samples. Additionally, a negligible amount of periclase phase was recognized in the samples. The average size of the synthesized particles was less than 200 nm. The presence of co-dopant led to an enhancement in the photoluminescent property of the synthesized samples. The maximum increase in photoluminescence intensity was obtained by Ba^（2＋）ions as a co-dopant. Condensed films of photoluminescence particles were produced by utilizing electrophoresis technique to deposit particles. The results showed that polyvinyl pyrrolidone was the best surface modifier to raise the mass deposition of the samples on the substrate.

关键词： Luminescence materials Forsterite Combustion syntheses Electrophoretic deposition

Abstraction of informed virtual geographic environments

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Geo-Spatial Information Science 2012年第1期15卷 27-36页

作者： mehdi MEKNI Eau Terre Environnement Center Institut National de Recherche Scientifique(INRS)Quebec CityCanada G1K 9A9

We propose a novel method for the automated generation of virtual geographic environments that allows using geographic information system data to build what we call informed virtual geographic environment(IVGE).The description of an IVGE integrates semantic information expressed using conceptual graphs,a standard knowledge representation *** addition,we propose an abstraction process that uses geometric,topologic,and semantic characteristics of geographic features to build a hierarchical graph-based structure describing this *** IVGE model enables the support of large-scale and complex geographic environment modeling for multiagent geo-simulations in which the agents are situated and with which they interact.

关键词： GIS informed virtual geographic environment(IVGE) abstraction process semantic information

Prediction of Seaward Slope Recession in Berm Breakwaters Using M5＇ Machine Learning Approach

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China Ocean Engineering 2016年第1期30卷 19-32页

作者： Alireza Sadat HOSSEINI mehdi SHAFIEEFAR Faculty of Civil and Environmental Engineering Tarbiat Modares University Tehran Iran

In the design process of berm breakwaters, their front slope recession has an inevitable rule in large number of model tests, and this parameter being studied. This research draws its data from Moghim＇s and Shekari＇s experiment results. These experiments consist of two different 2D model tests in two wave flumes, in which the berm recession to different sea state and structural parameters have been studied. Irregular waves with a JONSWAP spectrum were used in both test series. A total of 412 test results were used to cover the impact of sea state conditions such as wave height, wave period, storm duration and water depth at the toe of the structure, and structural parameters such as berm elevation from still water level, berm width and stone diameter on berm recession parameters. In this paper, a new set of equations for berm recession is derived using the M5＇ model tree as a machine learning approach. A comparison is made between the estimations by the new formula and the formulae recently given by other researchers to show the preference of new M5＇ approach.

关键词： berm breakwater recession experimental data M5' model tree machine learning method

Photoactive area modification in bulk heterojunction organic solar cells using optimization of electrochemically synthesized ZnO nanorods

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Chinese Physics B 2015年第11期24卷 422-427页

作者： mehdi Ahmadi Sajjad Rashidi Dafeh Department of Physics Faculty of Science Vali-e-Asr University of Rafsanjan

In this work, ZnO nanorod arrays grown by an electrochemical deposition method are investigated. The crucial parameters of length, diameter, and density of the nanorods are optimized over the synthesize process and nanorods growth time. Crystalline structure, morphologies, and optical properties of ZnO nanorod arrays are studied by different techniques such as x-ray diffraction, scanning electron microscope, atomic force microscope, and UV-visible transmission spectra. The ZnO nanorod arrays are employed in an inverted bulk heterojunction organic solar cell of Poly （3-hexylthiophene）：[6- 6] Phenyl-（6） butyric acid methyl ester to introduce more surface contact between the electron transporter layer and the active layer. Our results show that the deposition time is a very important factor to achieve the aligned and uniform ZnO nanorods with suitable surface density which is required for effective infiltration of active area into the ZnO nanorod spacing and make a maximum interfacial surface contact for electron collection, as overgrowing causes nanorods to be too dense and thick and results in high resistance and lower visible light transmittance. By optimizing the thickness of the active layer on top of ZnO nanorods, an improved efficiency of 3.17% with a high FF beyond 60% was achieved.

关键词： electrochemical deposition density-controlled ZnO nanorods inverted polymer solar cells active area modification