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Journal of Central South University 2017年第8期24卷 1837-1849页

作者： Sajad najafi Ravadanegh Mohammad Reza Jannati Oskuee Masoumeh Karimi Smart Distribution Grid Research Lab. Electrical Engineering DepartmentAzarbaijan Shahid Madani UniversityTabriz ***Iran

This research develops a comprehensive method to solve a combinatorial problem consisting of distribution system reconfiguration, capacitor allocation, and renewable energy resources sizing and siting simultaneously and to improve power system's accountability and system performance parameters. Due to finding solution which is closer to realistic characteristics, load forecasting, market price errors and the uncertainties related to the variable output power of wind based DG units are put in consideration. This work employs NSGA-II accompanied by the fuzzy set theory to solve the aforementioned multi-objective problem. The proposed scheme finally leads to a solution with a minimum voltage deviation, a maximum voltage stability, lower amount of pollutant and lower cost. The cost includes the installation costs of new equipment, reconfiguration costs, power loss cost, reliability cost, cost of energy purchased from power market, upgrade costs of lines and operation and maintenance costs of DGs. Therefore, the proposed methodology improves power quality, reliability and security in lower costs besides its preserve, with the operational indices of power distribution networks in acceptable level. To validate the proposed methodology's usefulness, it was applied on the IEEE 33-bus distribution system then the outcomes were compared with initial configuration.

关键词：可再生能源资源系统重构不确定性多目标规划模型配电网电容器配置网同步

New tetrazole-based organic dyes for dye-sensitized solar cells

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Journal of Energy Chemistry 2015年第6期24卷 770-778页

作者： Zahra Jafari Chermahini Alireza najafi Chermahini Hossein A Dabbagh Abbas Teimouri Department of Chemistry Isfahan University of Technology Chemistry Department Payame Noor University (PNU)

A series of new metal-free organic dyes that contain donors with triphenylamine or its derivatives and tetrazole-based acceptors were synthesized and characterized by photophysical, electrochemical, and the- oretical computational methods. They were applied in nanocrystalline TiO2 solar cells （DSSCs）. It is found that the introduction of diphenylamine units as antennas in the as-synthesized dyes could improve photo- voltaic performance compared with phenothiazine and carbazole units as antennas in DSSCs. The dye with （2H-tetrazol-5-yl） acrylonitrile electron acceptor also displayed the highest solar-to-electrical energy conver- sion efficiency.

关键词： Tetrazole Dye sensitized solar cells DFT Synthesis Anchoring group

Predicting motion picture box office performance using temporal tweet patterns

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International Journal of Intelligent Computing and Cybernetics 2018年第1期11卷 64-80页

作者： najafi Hossein Darryl W.Miller Department of Computer Science and Information Systems University of Wisconsin–River FallsRiver FallsWisconsinUSA Department of Management and Marketing University of Wisconsin–River FallsRiver FallsWisconsinUSA

Purpose–The purpose of this paper is to investigate temporal tweet patterns and their effectiveness in predicting the financial performance of a ***,how tweet patterns are formed prior to and after a movie’s release and their usefulness in predicting a movie’s success is ***/methodology/approach–Volume was measured and sentiment analysis was performed on a sampleof Tweetsposted fourdays beforeand afterthe releaseof 86 *** patternof tweeting for financially successful movies was compared with those that were financial *** temporal tweet patterns,a number of machine learning models were developed and their predictive performance was ***–Results show that the temporal patterns of tweet volume,length and sentiment differ between“hits”and“busts”in the days surrounding their *** with“busts”the tweet pattern for“hits”reveal higher volume,shorter length,and more favourable *** patterns in social media features occur days in advance of a movie’s release and can be used to develop models for predicting a movie’s ***/value–Analysis of temporal tweet patterns and their usefulness in predicting box office returns is the main contribution of this *** of this research could lead to development of analyticaltools allowingmotionpicture studiosto accurately predictand possiblyinfluencethe opening night box-office receipts prior to the release of the ***,the specific temporal tweet patterns presented by this work may be applied to problems in other areas of research.

关键词： Forecasting Social media Natural language processing Sentiment analysis Machine learning Box office

Kinematic Analysis and Design of a 3-DOF Translational Parallel Robot

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International Journal of Automation and computing 2017年第4期14卷 432-441页

作者： Mahmood Mazare Mostafa Taghizadeh M. Rasool najafi School of Mechanical Engineering Shahid Beheshti University Tehran lran Department of Engineering University of Qom Qom Iran

Parallel mechanisms are widely used in various fields of engineering and industrial applications such as machine tools, flight simulators, earthquake simulators, medical equipment, etc. Parallel mechanisms are restricted to some limitations such as irregular workspace, existence of singular points and complexity of control systems which should be studied and analyzed for effective and efficient use. In this research, a new machine tool with parallel mechanism which has three translational degrees of freedom is studied and the workspace and singular points are determined by deriving analytical equations and then utilizing of Matlab software. To do so, forward and inverse kinematics of the mechanism are obtained and workspace and singular points are calculated using a search algorithm. Afterward in order to validate the results, the proposed mechanism is simulated in automatic dynamics analysis of mechanical systems （ADAMS） software. Moreover, in order to investigate the quality of robot performance and dexterity of the mechanism in its workspace, global dexterity index （GDI） of the robot is calculated using Jacobean matrix at different positions of the mobile platform.

关键词： Kinematic analysis parallel robot workspace manipulability dexterity.

Numerical simulation of heavy fuel oil atomization using a pulsed pressure-swirl injector

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Chinese Journal of Chemical Engineering 2021年第4期34卷 61-69页

作者： S.M.A.najafi P.Mikaniki H.Ghassemi School of Mechanical Engineering Iran University of Science and TechnologyP.O.B.16765-163TehranIran

It is known that increasing the injection pressure reduces the breakup length and the droplet *** pulses,on the other hand,helps to atomize the liquid into finer droplets,similar to airassisted injectors but without altering the airtofuel *** further reduce the droplet size and breakup length,a novel injector type,called''Pulsed PressureSwirl"(PPS),is introduced in this work,which is a combination of pressureswirl and ultrasonic pulsed injectors.A pressureswirl atomizer was designed and fabricated specifically for Mazut HFO(Heavy Fuel Oil).The droplet formation process and droplet size distribution have been studied experimentally(by shadowgraphy high speed imaging)and numerically(with the opensource VolumeofFluid code Gerris).Changing liquid injection pressure effect on the spray angle and film thickness has been *** simulations have been used to study the primary breakup process and quantify the droplet size distributions,using different injection pulse frequencies and *** numerical results have revealed that the new injector concept successfully produces finer droplets and results in a decrease in the breakup length,especially when applying high pulse frequencies,with no significant changes in the spray angle.

关键词： Spray Heavy fuel oil Mazut Atomization Pulsed Pressure-Swirl Injector

Numerical Simulation of Vortex Engine Flow Field:One Phase and Two Phases

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Journal of Thermal Science 2009年第3期18卷 226-234页

作者： A.F.najafi S.D.Saemi M.H.Saidi Department of Energy Engineering Power and Water University of Technology Department of Mechanical Engineering Sharif University of Technology

Aiming at improving efficiency in combustion systems, the study on droplet behavior and its trajectory is of crucialimportance. Vortex engine is a kind of internal combustion engine which uses swirl flow to achieve highercombustion efficiency. One of the important advantages of designing vortex engine is to reduce the temperatureof walls by confining the combustion products in the inner vortex. The scopes of this investigation are to studyvortex engine flow field as well as effective parameters on fuel droplet behavior such as droplet diameter, dropletinitial velocity and inlet velocity of the flow field. The flow field is simulated using Reynolds Stress TransportModel (RSM). The Eulerian-Lagrangian method and the one-way coupling approach are employed to simulatetwo phase flow and dispersed phase in the chamber, respectively. A new method, based on computing pressureforce exerted on the droplet surface, is introduced to determine the distinction between using one-way andtwo-way coupling approaches. The results showed that the droplets with smaller diameter are more likely to followthe flow stream lines than bigger droplets, thus evaporate completely in the chamber. Moreover, droplets withgreater initial velocity have higher evaporation rate, yielding the existence of evaporation and combustion in theinner vortex. Additionally, the higher inlet velocity of continuous phase results in higher centrifugal force, leadsdroplets in question to deviate towards the wall faster.

关键词：进口流场数值模拟发动机涡旋二阶初始速度拉格朗日方法燃烧系统

Application of Stool-PCR test for diagnosis of Helicobacter pylori infection in children

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World Journal of Gastroenterology 2009年第4期15卷 484-488页

作者： Tahereh Falsafi Raha Favaedi Fatemeh Mahjoub Mehri najafi Department of Biology Alzahra University Department of Gastroenterology and Pathology Medical Center for Children

AIM:To evaluate the usefulness of stool-PCR test for diagnosis of Helicobacter pylori(H pylori)infection in pediatric populations. METHODS:Based on endoscopic features(including nodular gastritis,erosive duodenitis and ulcer)and/or a positive rapid urease test(RUT)obtained during endoscopy,28 children from a group of children admitted to the Children's Medical Center of Tehran for persistent upper gastrointestinal problems were selected to compare biopsy-based tests with *** gastric activity and bacterial density were graded by the updated Sydney system,and their first stool after endoscopy was stored at-70℃.Biopsies were cultured on modified campy-blood agar plates and identified by gram-staining,biochemical tests,and *** methods of phenol-chloroform and boiling were used for DNA extraction from H pylori isolates. Isolation of DNA from stool was performed using a stool DNA extraction kit(Bioneer Inc,Korea).PCR was performed using primers for detection of vacA,cagA,and 16srRNA genes in both isolates and stool. RESULTS:Sixteen out of 28 child patients(57%) were classified as H pylori positive by biopsy-based tests,of which 11(39%)were also positive by *** and specificity of stool-PCR was 62.5% and 92.3%respectively.H pylori was observed in histological sections for 10 out of 11 *** was observed between higher score of H pylori in histology and positivity of *** association was observed between the more severe form of gastritis and a positive stool-PCR. CONCLUSION:Association between higher score of H pylori in histology and a positive stool-PCR make it a very useful test for detection of H pylori active infection in *** also suggest that a simple stool-PCR method can be a useful test for detection of H pylori virulence genes in stool.

关键词：胃炎幽门疾病诊断临床

Interaction of Methane with Single-Walled Carbon Nanotubes: Role of Defects,Curvature and Nanotubes Type

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Communications in Theoretical Physics 2010年第5期53卷 987-993页

作者： M.D.Ganji M.Asghary A.A.najafi Department of Chemistry Islamic Azad University Department of Chemistry University of Payam-e-noor

我们从第一个原则调查围单人赛的碳 nanotubes (SWCNT ) 和甲烷分子的相互作用。吸附精力被计算，并且为典型半导体、金属性的 nanotubes 的甲烷亲密关系被比较。我们也在 SWCNT 的吸附能力上讨论结构的缺点和 nanotube 弯曲的角色。我... 详细信息

我们从第一个原则调查围单人赛的碳 nanotubes (SWCNT ) 和甲烷分子的相互作用。吸附精力被计算，并且为典型半导体、金属性的 nanotubes 的甲烷亲密关系被比较。我们也在 SWCNT 的吸附能力上讨论结构的缺点和 nanotube 弯曲的角色。我们能与半导体的 CNT 比较为金属性的 CNT 观察更大的吸附精力。有各种各样的直径的转弯急转 nanotubes 的获得的结果表明吸附精力为有更大的直径的 nanotubes 是更高的。为背叛试管，吸附精力为象甲烷分子在试管表面来临到缺点地点五边形，等边六角形，和七边形那样的各种各样的配置被计算。结果证明 introduce 缺点在 SWNT 上有重要贡献到甲烷的吸附机制。

关键词：单壁碳纳米管甲烷分子结构缺陷曲率半导体碳纳米管吸附能力管型 SWCNTs

Effect of ultrasonic irradiation on rheological properties of asphaltenic crude oils

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Petroleum Science 2012年第1期9卷 82-88页

作者： MOUSAVI Seyed Mohammadreza RAMAZANI Ahmad najafi Iman DAVACHI Seyed Mohammad Ultrasonic Research Group Chemical and Petroleum Engineering Department Sharif University of TechnologyAzadi Ave. Tehran Iran Chemical and Petroleum Engineering Department Sharif University of TechnologyAzadi Ave. Tehran Iran Ultrasonic Research Group Chemical and Petroleum Engineering Department Sharif University of Technology Azadi Ave. Tehran Iran Chemical and Petroleum Engineering Department Sharif University of Technology Azadi Ave. Tehran Iran

In this work, the rheological changes of several crude oil samples exposed to ultrasonic waves for different time intervals in addition to the effect of temperature on viscosity behavior of heavy crude oils were investigated using a series of steady shear flow and oscillatory tests. The colloidal structural evolutions of flocs in oil samples were illustrated by analysis of the size distribution of flocculated asphaltene particles （confocal microscopy tests）. The rheological investigations indicate that the ultrasonic irradiation dissolved heavy components in crude oil. After ultrasonic treatment, the Kouh-e-Mond crude oil was found to be pseudoplastic. In addition, confocal microscopy confirms that there was an optimum duration for ultrasonic irradiation, at which the viscosity and flocculation rate of asphaltenic crude oils reduced to the minimum values. The optimum was found to be approximately 40 min for the Kouh-e-Mond crude oil. Experimental results illustrate that the ultrasonic irradiation could disaggregate heavy colloid components in crude oil, and breakdown of asphaltene molecules would only occur in a specific time interval of irradiation. Also according to the temperature sweep test, the oil temperature rise caused by ultrasonic irradiation was not the main reason for theological changes of the crude oil and this alteration may be due to physical and chemical phenomena induced by sonication in crude oil.

关键词： Asphaltene ultrasonic technology pseudoplastic property viscoelastic property yield stress,flocculation time

A fuzzy logic model to predict the out-of-seam dilution in longwall mining

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International Journal of Mining Science and Technology 2015年第1期25卷 91-98页

作者： Ali Bahri najafi Mohammad Ali Ebrahimi Farsangi Golam Reza Saeedi Mining Engineering Department Shahid Bahonar University of Kerman

The longwall mining method is often affected by the out-of-seam dilution(OSD). Therefore, predicting and controlling of dilution are important factors for reducing mining costs. In this study, the fuzzy set theory and multiple regression models with parameters, including variation in seam thickness, dip of seam, seam thickness, depth of seam, and hydraulic radius as inputs to the models were applied to predict the OSD in the longwall coal panels. Field data obtained from Kerman and Tabas coal mines, Iran were used to develop and validate the models. Three indices including coefficient of determination(R2), root mean square error(RMSE) and variance account for(VAF) were used to evaluate the performance of the models. With 10 randomly selected datasets, for the linear, polynomial, power, exponential,and fuzzy logic models, R2, RSME and VAF are equal to(0.85, 4.4, 84.4),(0.61, 7.5, 59.6),(0.84, 4.5, 72.7),(0.80, 4.1, 79.6), and(0.97, 2.1, 95.7), respectively. The obtained results indicate that the fuzzy logic model predictor with R2= 0.97, RMSE = 2.1, and VAF = 95.7 performs better than the other models.

关键词：模糊逻辑模型模型预测长壁开采稀释长壁采煤法多元回归模型煤层厚度模糊集理论