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

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

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An algorithm for the anchor points of the PPS of the BCC model

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Financial Innovation 2022年第1期8卷 2368-2381页

作者： Dariush Akbarian Ali Akbar Bani Mohsen Rostamy-Malkhalifeh Farhad Hosseinzadeh lotfi Department of Mathematics Arak BranchIslamic Azad UniversityArakIran Department of Mathematics Gorgan BranchIslamic Azad UniversityGorganIran Department of Mathematics Science and Research BranchIslamic Azad UniversityTehranIran

Anchor points play an important role in data envelopment analysis theory and applications;they delineate the efficient part of the production possibility set(PPS)*** this paper,we propose an approach for finding the anchor points of the PPS of the Banker,Charnes and Cooper(BCC)*** approach is based on a variant of super-efficiency models and their *** necessary and sufficient conditions for the characterization of the anchor points are also ***,the applicability of the proposed model is illustrated with some numerical examples.

关键词： Data envelopment analysis(DEA) Anchor point Production Possibility Set(PPS) Efficient and inefficient boundary

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Microstructure and Sliding Wear Behaviour of Ni(Cr)-TiB_2 Coatings Deposited by HVOF Spraying of SHS Powders

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材料热处理学报 2004年第5B期25卷 1183-1186页

作者： Behnam lotfi Zohreh Sadeghian Faculty of Engineering Department of Materials Engineering Shahrecord University Shahrecord IranDepartment of Materials Science and Engineering Isfahan University of Technology Isfahan Iran

This work reports research concerning the microstructure and sliding wear behaviour of cermet coatings deposited by high velocity oxy-fuel (HVOF) spraying. Two cermets were prepared with the following target compositions namely, Ni (Cr)-65 wt.% TiB2 and Ni (Cr)-40 wt.% TiB2. Coating microstructures were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD), whilst microhardness and sliding wear tests were performed on the coatings to evaluate their performance. The HVOF sprayed deposits had layered, splat-like morphologies typical of thermally sprayed cermets. Coatings consisted primarily of TiB2 particles in a nickel-based binder phase. Other minor peaks in the XRD patterns belong to TiB, Ni2B, NiTiO3 and Ti2Oj. The coatings exhibit an amorphous halo in the diffraction pattern between 2 values of 40° and 50°. Sliding wear behaviour was examined using a conventional ball-on-disc apparatus. A sintered ceramic ball (A12O3) was employed as the counterface. The Ni (Cr)-65 wt.% TiB2 coating had a lower wear rate than Ni (Cr)-40 wt.% TiB2 coating. This may be related to the larger sizes of borides. Wear scar morphologies, on both coatings were examined by using SEM and EDAX detecting in order to establish the wear mechanism. Wear is proposed to proceed by subsurface cracking in these coatings.

关键词：显微结构滑动磨损 SHS HVOF Ni(Cr)-TiB2合金

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High performance novel flexible perovskite solar cell based on a low-cost-processed ZnO:Co electron transport layer

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Nano Research 2020年第9期13卷 2546-2555页

作者： Feriel Bouhjar lotfi Derbali BernabéMari Institut de Disseny i Fabricació(IDF)-Departament de Fisica Aplicada Universitat Politecnica de Valenciciy Cami de Vera s/n46022 ValenciaSpain Photovoltaic Laboratory Research and Technology Centre of Energy(CRTEn)Borj-Cedria Science and Technology Parky BP 952050 Hammam-LifTunisia Laboratory of Semiconductors Nanostructures and Advanced TechnologyResearch and Technology Center of Energy(CRTEn)Borj-Cedria Science and Technology ParkBP 952050 Hammam-LifTunisia Department of Physics College of Sciences and HumanitiesAl QuwayiyahShaqraa UniversityAl QuwayiyahSaudi Arabia

In this work,high quality uniform and dense nanostructured cobalt-doped zinc oxide(ZnO:Co)films were used as electron-transport layers in CH3NH3Pbl3-based planar heterojunction perovskite solar cells(PSCs)on a flexible conductive *** photo catalytically active ZnO:Co films were prepared by a low cost hydrothermal process using the aqueous solution of zinc nitrate hexahydrate,hexamethylenete-tramine and cobalt(II)nitrate ***:Co films were deposited on indium tin oxide(ITO)covered polyethylene terephthalate(PET)flexible *** growth was controlled by maintaining the autoclave temperature at 150℃for 4 *** CH3NH3Pbl3 layer was deposited on the ZnO:Co films by spin ***-OMeTAD was employed as a hole-transporting *** structural,morphology and optical properties of the grown ZnO nanostructures were characterized by X-ray diffraction(XRD),field-emission scanning electron microcopy(FESEM),energy-dispersive X-ray spectrometry(EDX),ultraviolet-visible(UV-Vis)and photoelectrochemical *** spectra showed that both ZnO and ZnO:Co nanorods had a hexagonal wurtzite structure with a strong preferred orientation along the(002)*** surface morphology of films was studied by FESEM and showed that both the pure and Co-doped ZnO films had hexagonal shaped *** the steady state,the ZnO electrode gave a photocurrent density of about 1.5 mA/***,the Co-doped ZnO electrode showed a photocurrent density of about 6 mA/cm^2,which is 4-fold higher than that of the ZnO *** on the above synthesized Co-doped ZnO films,the photovoltaic performance of PSCs was *** Co-doped ZnO layers had a significant impact on the photovoltaic conversion efficiency(PCE)of the *** latter was attributed to an efficient charge separation and transport due to the better coverage of perovskite on the nanostructured Co-doped ZnO *** a result,the measured PCE under standard solar conditions(A M 1.5G,100 mW/cm^2)r

关键词： perovskite solar cell ZnO nanorods hydrotherm al deposition X-ray diffraction(XRD)analysis field-em ission scanning electron m icrocopy(FESEM)analysis photoelectrochem ical properties

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Hydrogen Detection With FBG Sensor Technology for Disaster Prevention

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Photonic Sensors 2013年第3期3卷 214-223页

作者： Said SAAD lotfi HASSINE Group of Electronics and Quantum Physics Laboratory of Advanced Materials and Quantum Phenomena Faculty of Sciences of Tunis 2092 Tunisia National Institute of Applied Sciences and Technology University of Carthage North Urban Center of Tunis-B.P.676 Cedex Tunis-1080 Tunisia

Three fiber Bragg grating (FBG) sensors systems for hydrogen detection are presented using the classic Pd (palladium) coating technique (500 nm) as the hydrogen sensitive film and titanium (Ti) as the adhesive layer with the etched cladding. These systems are compared and used for disaster environment prevention in hydrogen leakage environment where higher values than the normal are presented which increase the risk of explosion. With these systems, 0.1%–4% of the hydrogen volume concentration range in the volume ratio was detected and monitored experimentally in the test room with the very sensitive and stable value which reached 60 pm/1% H2. In addition, a fast response time, about 6 s, was obtained with an advanced sensor.

关键词：传感器技术氢气泄漏氢检测 FBG 光纤布喇格光栅防灾试验室试验涂覆技术

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Impurity effects on electrical conductivity of doped bilayer graphene in the presence of a bias voltage

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Chinese Physics B 2016年第7期25卷 316-323页

作者： E lotfi H Rezania B Arghavaninia M Yarmohammadi Department of Physics Sanandaj Branch Islamic Azad University Department of Physics Razi University Department of Physics Kermanshah Branch Islamic Azad University Young researchers and Elite Club Kermanshah Branch Islamic Azad University

We address the electrical conductivity of bilayer graphene as a function of temperature, impurity concentration, and scattering strength in the presence of a finite bias voltage at finite doping, beginning with a description of the tight-binding model using the linear response theory and Green＇s function approach. Our results show a linear behavior at high doping for the case of high bias voltage. The effects of electron doping on the electrical conductivity have been studied via changing the electronic chemical potential. We also discuss and analyze how the bias voltage affects the temperature behavior of the electrical conductivity. Finally, we study the behavior of the electrical conductivity as a function of the impurity concentration and scattering strength for different bias voltages and chemical potentials respectively. The electrical conductivity is found to be monotonically decreasing with impurity scattering strength due to the increased scattering among electrons at higher impurity scattering strength.

关键词： bilayer graphene Green's function electrical conductivity

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Depression among medical students in Tunisia:Prevalence and associated factors

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World Journal of Psychiatry 2023年第10期13卷 772-783页

作者： Badii Amamou Sondess Alouani Amjed Ben Haouala Saoussen Alouani Mohamed Ayoub Tlili Ahmed Mhalla Ferid Zaafrane lotfi Gaha Department of Psychiatry Fattouma Bourguiba University Hospital of MonastirMonastir 5000Tunisia Department of Family and Community Medicine Faculty of Medicine of SousseSousse 4002Tunisia

BACKGROUND Medical school is known for its lengthy process,which is both physically and emotionally ***’mental balance would shrink as they progress in their medical training.A systematic review and meta-analysis reported that the prevalence of depressive symptoms among medical students remained relatively constant at 27.2%.AIM To assess the prevalence of depressive symptoms among Tunisian medical students and evaluate its associated *** This is a descriptive cross-sectional study that was carried out in the second semester of the academic year 2017/2018,between April 2018 and July 2018 among 1138 medical *** were collected using a socio-demographic questionnaire and the Beck Depression Inventory-II(BDI-II).RESULTS Sixty-four percent(n=728)of the participants had depressive symptoms,of which 266(23.4%)met the criteria for mild,271(23.8%)for moderate,and 191(16.8%)for severe depressive *** gender,low socio-economic level,smoking habits and history of mental disorder,performing leisure and physical activities,satisfaction toward a career choice,and happiness perception were the main prognostic factors for depression among medical *** academic grades may not be considered a prognostic factor,final-year students appeared to be less depressive than their *** These findings give insight into mental health issues and comorbidities among Tunisian medical *** is a hopeful request for decision-makers and academic authorities to set serious measures and draw effective interventions to minimize the currency of psychological distress among this subpopulation.

关键词： Depression Psychiatry Medical students Mental health Beck Depression Inventory Tunisia

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Analysis and optimal synthesis of single loop spatial mechanisms

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第9期12卷 665-679页

作者： Med Amine LARIBI lotfi ROMDHANE Sad ZEGHLOUL Laboratoire de Génie Mécanique LAB-MA-05 Ecole Nationale d'Ingénieurs de Sousse Institut Pprime-UPR 3346 CNRS-Université de Poitiers-ENSMA Département Génie Mécanique et Systémes Complexes SP2MIBP30179 86962 Futuroscope France

In this work, a systematic approach is presented to obtain the input-output equations of a single loop 4-bar spatial mechanisms. The dialytic method along with Denavit-Hartenberg parameters can be used to obtain these equations efficiently. A genetic algorithm (GA) has been used to solve the problem of spatial mechanisms synthesis. Two types of mechanisms, e.g., RSCR and RSPC (R: revolute; S: spherical; C: cylindrical; P: prismatic), have illustrated the application of the GA to solve the problem of function generation and path generation. In some cases, the GA method becomes trapped in a local minimum. A combined GA-fuzzy logic (GA-FL) method is then used to improve the final result. The results show that GAs, combined with an adequate description of the mechanism, are well suited for spatial mechanism synthesis problems and have neither dificulties inherent to the choice of the initial feasible guess, nor a problem of convergence, as it is the case for deterministic methods.

关键词：空间机制基因算法模糊的逻辑(GA-FL ) 方法 Denevit-Hartenberg 参数机制合成

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Production of single-walled carbon nanotubes from methane over Co-Mo/MgO nanocatalyst:A comparative study of fixed and fluidized bed reactors

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Journal of Natural Gas Chemistry 2011年第4期20卷 372-376页

作者： Alimorad Rashidi Roghayeh lotfi Ehsaneh Fakhrmosavi Masoud Zare Nanotechnology Research Center Research Institute of Petroleum Industry(R.I.P.I.)West Blvd.of Azadi Sport Complex

In this study,the performances of fixed and fluidized bed reactors in the production of single-walled carbon nanotubes（SWNTs）have been *** both reactors,single-walled carbon nanotubes were grown by catalytic chemical vapor decomposition（CCVD）of methane over Co-Mo/MgO nanocatalyst under two different operating *** synthesized samples were characterized by TEM,TGA and Raman *** is found that the performance of a fluidized bed in the synthesis of carbon nanotubes is much better than that of a fixed *** quality of carbon nanotubes obtained from the fluidized bed was significantly higher than that from the fixed bed and the former one with the ID/IG ratio of 0.11 while the latter one with the ID/IG ratio of ***,the yield of SWNTs in the fluidized bed was 92 wt%,while it was 78 wt%in the fixed *** advantages of fluidized bed reactors for the synthesis of carbon nanotubes can be attributed to more available space for the growth of carbon nanotubes and more uniform temperature and concentration profiles.

关键词： single-walled carbon nanotubes chemical vapor deposition fixed bed reactor fluidized bed reactor

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Lower Bounds for Local Cohomology Modules with Respect to a Pair of Ideals

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Algebra Colloquium 2016年第2期23卷 329-334页

作者： M. lotfi Parsa Sh. Payrovi Faculty of Science Sayyed Jamaleddin Asadabadi University Postal code: 65418-3-5583 Asadabad Iran Department of Mathematics Imam Khomeini International University Postal code: 34149-1-6818 Qazvin Iran

Let R be a Noetherian ring, I and J two ideals of R, M an R-module and t an integer. Let S be a Serre subcategory of the category of R-modules satisfying the co ondition CI, and N be a finitely generated R-module with SuppRN= V（a） for some a ∈ W（I, J）. It is shown that if ExtR^J（N,HI^i,J（M）） ∈ S for all i 〈 t and all j 〈 t - i, then Ha^i（M） ∈ S for all i 〈 t. Let S be the class of all R-modules N with divmR N ≤ k, where k is an integer. It is proved that if Ha^i（M） ∈ S for all i 〈 t and all a ∈ W（I, J）, then HI^i,j（M） ∈ S for all i 〈 t. It follows that inf{i ： HI^i,j（M） S} = inf（inf{i ： Ha^i（M） S）： a ∈W（I,J）}.

关键词： extension functor local cohomology Serre subcategory

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