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Experimental investigation of typical surface treatment effect on velocity fluctuations in turbulent flow around an airfoil

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Chinese Journal of Aeronautics 2023年第10期36卷 112-123页

作者： babak ELHAMI Mojtaba DEHGHAN MANSHADI Ali Akbar DEHGHAN Faculty of Mechanical Engineering Malek Ashtar University of TechnologyIsfahan 177415875Iran Mechanical Engineering Faculty Yazd UniversityYazd ***Iran

Noise reduction of different airfoils is important because these sections are used in wind turbines,propellers,and aircraft *** methods are used for passive noise reduction of *** of these methods is the use of surface *** this research,the effect of the typical surface treatment element(finlets)on the vortex structure at different frequencies in the turbulent flow created on the NACA2412 section is *** this purpose,one-dimensional hot wire probe is *** used surface treatment in this research has a special geometry and the distance between two consecutive finlets is 6 mm(S=6 mm).This study shows that this surface treatment element can be used for noise reduction in high *** result of this research is the suggestion of the most suitable position to install this special surface treatment element to reduce vortex energy in all frequency *** installation location is determined based on a dimensionless parameter(X_(aft)/h).

关键词： Finlet spacing Passive noise reduction Sound Pressure Level(SPL) Surface treatment(finlets) Velocity power spectral density

Optimal design analysis of a tubular heat exchanger network with extended surfaces using multi-objective constructal optimization

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Frontiers in Energy 2022年第5期16卷 862-875页

作者： Hassan HAJABDOLLAHI Mohammad SHAFIEY DEHAJ babak MASOUMPOUR Mohammad ATAEIZADEH Department of Mechanical Engineering Vali-e-Asr University of RafsanjanRafsanjan ***Iran

The present work aims to investigate the influence of extended surfaces(fins)on the multi-objective optimization of a tubular heat exchanger network(THEN).An increase in the heat transfer area using various extended surfaces(fins)to enhance the performance of the heat exchanger was used while considering the effectiveness and total heat transfer area as two objective *** addition to the simulation of simple fins,a new set of fins,called constructal fins,was designed based on the constructal *** heat exchanger network design parameters were chosen as optimization variables,and optimization results were achieved in such a way as to enhance the effectiveness and decrease the total heat transfer *** results show the importance of constructal fins in improving the objective functions of heat *** instance,the simple fins case enhances the effectiveness by up to 5.3%compared to that without fins(usual heat exchanger)while using constructal fins,in addition to the 7%increment of effectiveness,reduces the total heat transfer area by 9.47%.In order to optimize the heat exchanger,the heat transfer rate and cold fluid temperature must increase,and at the same time,the hot exiting fluid temperature should decrease at the same constant total heat transfer area,which is higher in the constructal fins ***,optimized design variables were studied for different cases,and the effects of various fins were reported.

关键词： constructal theory extended surface effectiveness total heat transfer area multi-objective optimization

Laser-assisted synthesis of Au NPs on MgO/chitosan:Applications in electrochemical hydrogen storage

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镁合金学报(英文) 2023年第6期11卷 2072-2083页

作者： babak Jaleh Aida Moradi Mahtab Eslamipanah Sadegh Khazalpour Haniyeh Tahzibi Saeid Azizian Manoj B.Gawande Department of Physics Bu-Ali Sina UniversityHamedanIran Faculty of Chemistry Bu-Ali Sina University65174HamedanIran Department of Physical Chemistry Faculty of ChemistryBu-Ali Sina UniversityHamedanIran Department of Industrial and Engineering Chemistry Institute of Chemical TechnologyMumbai-Marathwada CampusJalna 431203MaharashtraIndia CEET Nanotechnology CentreVŠB–Technical University of Ostrava17.listopadu 2172/1570800 Ostrava-PorubaCzech Republic

Hydrogen with high energy density is an environmental alternative to fossil fuels which can respond to the demand for energy considering environmental *** can be stored on porous materials employing physical interaction(*** process).The H2storage capacity of materials can be evaluated through electrochemical ***,a fast and straightforward approach was employed to fabricate magnesium oxide/chitosan/Au nanoparticles(Mg O/CS/Au)nanocomposites with porous structure for electrochemical hydrogen ***,laser ablation in water as a fast and green method was utilized to obtain Au nanoparticles(Au NPs).The obtained Au NPs were loaded on Mg O/CS nanocomposite through physical *** and morphological investigation of nanocomposites display spherically shaped Au NPs with a diameter of 49–58 nm agglomerated on the Mg O/*** casting,the fast and cost-effective method was deployed to deposit the benign,and reusable Mg O/CS/Au-x(x is Au NPs weight percentage of 1,3 and 5 wt.%)nanocomposites on stainless steel mesh and their electrochemical hydrogen storage were measured by cyclic voltammetry(CV),indicating good stability and significant hydrogen storage capacity(28 C/g)after 300 CV scans for MgO/CS/Au-1 sample.

关键词： Magnesium oxide(MgO) Chitosan(CS) Gold nanoparticles(Au NPs) Hydrogen storage

纳米黏土与再生聚酯纤维混合处理黏土砂的抗剪强度

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Journal of Central South University 2022年第1期29卷 259-269页

作者： Mehrdad KHOLGHIFARD babak AMINI BEHBAHANI Department of Civil Engineering Yasooj BranchIslamic Azad UniversityYasooj ***Iran

近年来,以纳米尺度和纳米颗粒以及定向或随机分布的离散单元(如纤维)来加固土体的材料已被广泛应用于岩土工程中。本研究的主要目的是研究纳米黏土与再生聚酯纤维混合作为一种新的稳定材料对土壤力学行为的影响。对于未强化和三种纤维... 详细信息

近年来,以纳米尺度和纳米颗粒以及定向或随机分布的离散单元(如纤维)来加固土体的材料已被广泛应用于岩土工程中。本研究的主要目的是研究纳米黏土与再生聚酯纤维混合作为一种新的稳定材料对土壤力学行为的影响。对于未强化和三种纤维含量介于0.1%和0.5%的强化土壤标本,以及三种纳米黏土含量介于0.5%和1.5%的土壤进行排干剪切和压缩测试。结果表明,纳米黏土-再生聚酯纤维与土壤混合后,土壤的抗剪强度提高了41%,黏聚力提高了174%。此外,纤维粗糙的波状表面使土颗粒之间产生粘结和摩擦,阻止土颗粒的运动,从而提高土的强度。

关键词：土壤处理纳米黏土再生聚酯纤维抗剪强度黏土砂

Accounting for Heterogeneity in Stop Frequency Models of Work Tours Using Latent Class Poisson Models

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Journal of Transportation Technologies 2023年第2期13卷 243-261页

作者： babak Mirzazadeh KLD Engineering P.C. Islandia NY USA

Stop frequency models, as one of the elements of activity based models, represent an important part of travel behavior. Unobserved heterogeneity across the travelers should be taken into consideration to prevent biasedness and inconsistency in the estimated parameters in the stop frequency models. Additionally, previous studies on the stop frequency have mostly been done in larger metropolitan areas and less attention has been paid to the areas with less population. This study addresses these gaps by using 2012 travel data from a medium sized U.S. urban area using the work tour for the case study. Stop in the work tour were classified into three groups of outbound leg, work based subtour, and inbound leg of the commutes. Latent Class Poisson Regression Models were used to analyze the data. The results indicate the presence of heterogeneity across the commuters. Using latent class models significantly improves the predictive power of the models compared to regular one class Poisson regression models. In contrast to one class Poisson models, gender becomes insignificant in predicting the number of tours when unobserved heterogeneity is accounted for. The commuters are associated with increased stops on their work based subtour when the employment density of service-related occupations increases in their work zone, but employment density of retail employment does not significantly contribute to the stop making likelihood of the commuters. Additionally, an increase in the number of work tours was associated with fewer stops on the inbound leg of the commute. The results of this study suggest the consideration of unobserved heterogeneity in the stop frequency models and help transportation agencies and policy makers make better inferences from such models.

关键词： Activity Based Model Work Tour Stop Frequency Latent Class Poisson Regression Model

Tectonic Setting of the Barm Firuz Lake,Zagros Mountains,Iran:Inferred from Structural and Karstic Evidence

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Journal of Earth Science 2014年第5期25卷 932-938页

作者： babak Samani Faculty of Earth Sciences Shahid Chamran UniversityAhvaz Iran

This paper presents the role of tectonic and karstic processes in the formation and evolution of Barm Firuz Lake within the Zagros Mountains of Iran. This lake with elevation of 3 340 m from sea level is located in the crest of the Barm Firuz anticline. Results show that the structural evolution of the Barme Firuz Lake is related to both tectonic and karst processes. Therefore the term of tectonokarstic has been used for structural evolution of the lake. Structural studies especially on the stylolite structures revealed the occurrence of an important component of simple shear deformation in the study area. Based on structural and karstic evidence around the lake, the fault-dissolution sink model with oblique pure shear component is suggested as kinematic model of the Barm Firuz Lake evolution in the Zagros Mountains of Iran.

关键词： tectonic karst Barm Firuz Lake Zagros Mountains lran.

Self-assembled vesicle–colloid hybrid swimmers:Non-reciprocal strokes with reciprocal actuation

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Chinese Physics B 2020年第6期29卷 30-36页

作者： Jaime Agudo-Canalejo babak Nasouri Max Planck Institute for Dynamics and Self-Organization(MPIDS) 37077 GoettingenGermany

We consider a self-assembled hybrid system,composed of a bilayer vesicle to which a number of colloids are *** on known results of membrane curvature elasticity,we predict that,for sufficiently deflated prolate vesicles,the colloids can self-assemble into a ring at a finite distance away from the vesicle equator,thus breaking the up–down symmetry in the *** the relative variation of the position of the colloidal ring along the vesicle endows the system with an effective elasticity,periodic cycles of inflation and deflation can lead to non-reciprocal shape changes of the vesicle–colloid hybrid,allowing it to swim in a low Reynolds number environment under reciprocal *** design several actuation protocols that allow control over the swimming direction.

关键词： vesicles colloids microswimmers curvature

A new robust predictive model for lost circulation rate using convolutional neural network:A case study from Marun Oilfield

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Petroleum 2023年第3期9卷 468-485页

作者： Farshad Jafarizadeh babak Larki Bamdad Kazemi Mohammad Mehrad Sina Rashidi Jalil Ghavidel Neycharan Mehdi Gandomgoun Mohammad Hossein Gandomgoun Department of Petroleum Engineering Amirkabir University of TechnologyTehranIran Department of Petroleum Engineering Omidiyeh Branch of Islamic Azad UniversityOmidiyehIran Science and Research Branch Islamic Azad UniversityTehranIran Faculty of Mining Petroleum and Geophysics EngineeringShahrood University of TechnologyShahroodIran Department of Information Technology and Computer Engineering Shahid Madani University of AzerbaijanTabrizIran Faculty of Petroleum Engineering Sahand University of TechnologyTabrizIran

A major cause of some of serious issues encountered in a drilling project,including wellbore instability,formation damage,and drilling string stuck e which are known to increase non-productive time(NPT)and hence the drilling cost e is what we know as mud *** mud loss can be prevented or at least significantly reduced by taking proper measures beforehand provided the position and intensity of such loss can be properly predicted using an accurate predictor ***,in this study,we used the convolutional neural network(CNN)and hybridized forms of multilayer extreme learning machine(MELM)and least square support vector machine(LSSVM)with the Cuckoo optimization algorithm(COA),particle swarm optimization(PSO),and genetic algorithm(GA)for modeling the mud loss rate based on drilling data,mud properties,and geological information of 305 drilling wells penetrating the Marun *** this purpose,we began by a pre-processing step to attenuate the effect of noise using the Savitzky-Golay *** whole set of available data was divided into the modeling(including 2300 data points)and the validation(including 483 data points)***,the second generation of the non-dominated sorting genetic algorithm(NSGA-Ⅱ)was applied to the modeling data to identify the most significant features for estimating the mud *** results showed that the prediction accuracy increased with the number of selected features,but the increase became negligible when the number of selected features exceeded ***,the following 9 features were selected as input to the intelligent algorithms(IAs):pump pressure,mud weight,fracture pressure,pore pressure,depth,gel 10 min/gel 10 s,fan 600/fan 300,flowrate,and formation *** of the hybrid algorithms and simple forms of LSSVM and CNN to the training data(80%of the modeling data,i.e.1840 data points)showed that all of the models tend to underestimate the mud loss at higher mud loss rates,although the CNN exhibited l

关键词： Lost circulation prediction Artificial intelligence Deep learning Feature selection

Estimating Network Connectedness of Financial Markets and Commodities

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Journal of Systems Science and Systems Engineering 2020年第5期29卷 572-589页

作者： Ehsan Bagheri Seyed babak Ebrahimi Financial Engineering Group Faculty of Industrial EngineeringK.N.Toosi University of TechnologyTehranIran

We investigate the directional volatility and return network connectedness among stock,commodity,bond,currency and cryptocurrency *** period of study covers Feb 2006 until August *** utilize and expand Diebold and Yilmaz(20142015)connectedness measurement;accordingly,in the variance decomposition structure,we use Hierarchical Vector Autoregression(HVAR)to estimate high dimensional networks more *** empirical results show that markets are highly connected,especially during *** stock markets are the net receiver of shocks,while European and American stock markets are the net transmitter of shocks to other *** pairwise connectedness results suggest that among stock markets,DAX-CAC 40,FTSE 100-CAC 40 and S&P 500-S&P_TSX index are more integrated through connectedness than the *** other markets,WTI crude oil-Brent crude oil,30-Year bond and 10-Year bond,Dollar Index futures-EUR/USD have notable *** terms of cryptocurrencies,they contribute insignificantly to other markets and are highly integrated with each *** and cryptocurrencies seem to be good choices for investors to hedge during a crisis.

关键词： Financial markets network connectedness econometrics commodity