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robust non-aggressive three-axis attitude control of spacecraft:dynamic sliding mode approach

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Control Theory and Technology 2023年第4期21卷 505-514页

作者： Javad Nikyar farhad Bayat MohammadAli Mohammadkhani Department of Electrical Engineering University of ZanjanUniversity Blvd.ZanjanZanjan***Iran Department of Electrical Engineering Technical and Vocational UniversityBrazil St.TehranTehran***Iran

Conventional sliding mode control(SMC)has been extensively applied in controlling spacecrafts because of its appealing characteristics such as robustness and a simple design *** methods such as second-order sliding modes and discontinuous controllers are applied for the SMC ***,the main problems of these methods are convergence and error tracking in a finite amount of *** paper combines an improved dynamic sliding mode controller and model predictive controller for spacecrafts to solve the chattering phenomenon in traditional sliding mode *** this aim,this paper develops dynamic sliding mode control for spacecraft’s applications to omit the chattering *** proposed approach shows robust attitude tracking by a set of reaction wheels and stabilizes the spacecraft subject to disturbances and *** proposed method improves the performance of the SMC for spacecraft by avoiding chattering.A set of simulation results are provided that show the advantages and improvements of this approach(in some sense)compared to SMC approaches.

关键词： Dynamic sliding mode control Attitude control Model predictive control Spacecrafts

Experiments on two-phase flow in hydraulic jump on pebbled rough bed:Part 2–Bubble clustering

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Water Science and Engineering 2023年第4期16卷 369-380页

作者： farhad Bahmanpouri Carlo Gualtieri Hubert Chanson Civil Architectural and Environmental Engineering Department(DICEA)The University of Napoli Federico IIVia Claudio 21Napoli 80125Italy School of Civil Engineering The University of QueenslandBrisbaneQLD 4072Australia

A survey on bubble clustering in air–water flow processes may provide signiﬁcant insights into turbulent two-phaseﬂ*** processes have been studied in plunging jets,dropshafts,and hydraulic jumps on a smooth *** a first attempt,this study examined the bubble clustering process in hydraulic jumps on a pebbled rough bed using experimental data for 1.70r_(1)r_(1) denoting the inflow Froude number).The basic properties of particle grouping and clustering,including the number of clusters,the dimensionless number of clusters per second,the percentage of clustered bubbles,and the number of bubbles per cluster,were analyzed based on two *** both criteria,the maximum cluster count rate was greater on the rough bed than on the smooth bed,suggesting greater interactions between turbulence and bubbly flow on the rough *** results were consistent with the longitudinal distribution of the interfacial velocity using one of the *** addition,the clustering process was analyzed using a different approach:the interparticle arrival time of *** comparison showed that the bubbly flow structure had a greater density of bubbles per unitﬂux on the rough bed than on the smooth *** roughness was the dominant parameter close to the jump *** downstream,Fr_(1) ***,the rate of bubble density decreased more rapidly for the hydraulic jump with the lowest Fr_(1).

关键词： Hydraulic jump Pebbled rough bed Clustering analysis Interparticle arrival time Two-phase flow

A Novel IoT Application recommendation System Using Metaheuristic Multi-Criteria Analysis

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Computer Systems Science & Engineering 2021年第5期37卷 149-158页

作者： Mohammed Hayder Kadhim farhad Mardukhi Department of Computer Engineering and Information Technology Razi UniversityKermanshahIran

There are a variety of Internet of Things(IoT)applications that cover different aspects of daily *** of these applications has different criteria and sub-criteria,making it difficult for the user to *** requires an automated approach to select IoT applications by considering *** paper presents a novel recommendation system for presenting applications on the ***,using the analytic hierarchy process(AHP),a multi-layer architecture of the criteria and sub-criteria in IoT applications is *** architecture is used to evaluate and rank IoT *** a result,finding the weight of the criteria and subcriteria requires a metaheuristic *** this paper,a sequential quadratic programming algorithm is used to find the optimal weight of the criteria and sub-criteria *** the best of our knowledge,this is the first study to use an analysis of metaheuristic criteria and sub-criteria to design an IoT application recommendation *** evaluations and comparisons in the experimental results section show that the proposed method is a comprehensive and reliable model for the construction of an IoT applications recommendation system.

关键词： Internet of Things smart objects recommendation system multicriteria analysis sequential quadratic programming

Effects of modified graphene oxide(GO) nanofluid on wettability and IFT changes: Experimental study for EOr applications

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Petroleum Science 2022年第4期19卷 1779-1792页

作者： Ehsan Jafarbeigi farhad Salimi Ehsan Kamari Mohsen Mansouri Department of Chemical Engineering Kermanshah BranchIslamic Azad UniversityKermanshahIran Department of Petroleum Engineering Research Institute of Petroleum IndustryTehranIran Department of Chemical Engineering llam UniversityllamIran

The application of nanoparticles(NPs) in enhanced oil recovery(EOr) offers a practical approach to resolving some surface-related problems encountered in contemporary technological processes. In this study, graphene oxide nanosheets(GONs) were synthesized by Hummer's method and, then, were subjected to surface modification by hexamethyldisilazane(HMDS) and diazonium sulfonic(DS) compounds. The new combination was known as GO-Su-HMDS. The potential stability of GO-Su-HMDS nanofluids(NFs) was investigated using the zeta(ζ) potential test. A comparative study of the effect of the synthesized NFs on wettability alteration of the reservoir rock was performed using interfacial tension(IFT) and contact angle experiments. According to the results of this study, the contact angle decreased from the initial value of 161.(oil wet) to 35.(water wet). In addition, IFT decreased from18.45 mN/m for deionized(DI) water to 8.8 mN/m for 500 ppm GO-Su-HMDS NF. Moreover, the results of flooding experiments showed that the NPs of a GO-Su-HMDS concentration of 400 and 500 ppm could increase the oil recovery by 20% and 19%, respectively. The experimental results showed that GO-SuHMDS NFs with a concentration of 500 ppm have the best efficiency in terms of altering the wettability of the rock from oil wet to water wet. Thus, it can be said that this nanofluid can reduce the contact angle and IFT and also increase the sweeping efficiency of oil.

关键词： Wettability alteration Graphene oxide Contact angle Interfacial tension Zeta potential

Calculation of thermal neutron albedo for mono-material and bi-material reflectors

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Nuclear Science and Techniques 2018年第9期29卷 185-191页

作者： Sara Azimkhani farhad Zolfagharpour Farhood Ziaie Department of Physics University of Mohaghegh Ardabili radiation Application research School Nuclear Science & Technology Research Institute

Thermal neutron albedo has been investigated for different thicknesses of mono-material and bi-material reflectors. An equation has been obtained for a bi-material reflector by considering the neutron diffusion equation. The bi-material reflector consists of binary combinations of water, graphite, lead, and polyethylene. An experimental measurement of thermal neutron albedo has also been conducted for mono-material and bi-material reflectors by using a^(241) Am–Be(5.2 Ci) neutron source and a BF3 detector. The maximum value of thermal neutron albedo was obtained for a polyethylene–water combination(0.95 ± 0.02).

关键词： Neutron current Bi-material reflector Thermal neutron albedo BF3 detector reflection Diffusion equation

Multiple damage detection in complex bridges based on strain energy extracted from single point measurement

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Frontiers of Structural and Civil Engineering 2020年第3期14卷 722-730页

作者： Alireza ArABHA NAJAFABADI farhad DANESHJOO Hamid reza AHMADI Department of Structural Engineering RoadHousing&Urban Development Research CenterTehran 13145-1696Iran Department of Structural Engineering Faculty of Civil and Environmental EngineeringTarbiat Modares UniversityTehran 14115-397Iran Department of Civil Engineering Faculty of EngineeringUniversity of MaraghehMaragheh 55136-553Iran

Strain Energy of the structure can be changed with the damage at the damage *** accurate detection of the damage location using this index in a force system is dependent on the degree of accuracy in determining the structure deformation function before and after *** use of modal-based methods to identify damage in complex bridges is always associated with problems due to the need to consider the effects of higher modes and the adverse effct of operational conditions on the extraction of structural modal *** this paper,the deformation of the structure was determined by the concept of influence line using the Betti-Maxwell *** two damage detection indicators were developed based on strain energy *** indices were presented separately for bending and torsion *** element analysis of a five-span concrete curved bridge was done to validate the stated *** was simulated by decreasing stiffness at different sections of the *** response regarding displacement ofa point on the deck was measured along each span by passing a moving load on the bridge at very low *** of the strain energy extracted from displacement influence line and the strain energy extracted from the rotational displacement influence line(SErIL)were calculated for the studied *** results show that the proposed methods have well identified the location of the damage by significantly reducing the number of sensors required to record the ***,the location of symmetric damages is detected with high resolution using SErIL.

关键词： damage detection strain energy infuence line complex bridges rotation displacement

Sclerosing Mucoepidermoid Cancer: A Unique Entity

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Achalasia: A review of Western and Iranian experiences

Open Journal of Endocrine and Metabolic Diseases（内分泌与新陈代谢疾病期刊） 2024年第5期 107页

作者： Ashima Mittal Christina Dimech farhad Hasan Gayatri Jaiswal

来源：博看期刊评论

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World Journal of Gastroenterology 2009年第40期15卷 5000-5009页

作者： Javad Mikaeli farhad Islami reza Malekzadeh Digestive Disease research Center Shariati HospitalTehran University of Medical Sciences International Agency for research on Cancer King's College London Thames Cancer Registry

Achalasia is a primary motor disorder of the eso-phagus, in which esophageal emptying is impaired. Diagnosis of achalasia is based on clinical fi ndings. The diagnosis is confirmed by radiographic, endoscopic, and manometric evaluations. Several treatments for achalasia have been introduced. We searched the PubMed Database for original articles and meta-analyses about achalasia to summarize the current knowledge regarding this disease, with particular focus on different procedures that are used for treatment of achalasia. We also report the Iranian experience of treatment of this disease, since it could be considered as a model for medium-resource countries. Myotomy, particularly laparoscopic myotomy with fundoplication, is the most effective treatment for achalasia. Compared to other treatments, however, the initial cost of myotomy is usually higher and the recovery period is longer. When performing myotomy is not indicated or not possible, graded pneumatic dilation with slow rate of balloon inflation seems to be an effective and safe initial alternative. Injection of botulinum toxin into the lower esophageal sphincter before pneumatic dilation may increase remission rates. However, this needs to be conf irmed in further studies. Due to lack of adequate information regarding the role of expandable stents in the treatment of achalasia, insertion of stents does not currently seem to be a recommended treatment. In summary, laparoscopic myotomy can be considered as the procedure of choice for treatment of achalasia. Graded pneumatic dilation is an effective alternative when the performance of myotomy is not possible for any reason.

关键词： Achalasia Esophagus Motility Treatment

Addition of IrO2 to ruO2+TiO2 coated anodes and its effect on electrochemical performance of anodes in acid media

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Progress in Natural Science:Materials International 2014年第2期24卷 134-141页

作者： farhad Moradi Changiz Dehghanian School of Metallurgy and Materials Engineering University College of Engineering University of Tehran

Ternary mixed metal oxide coatings with the nominal composition Irxru(0.6-x)Ti0.4O2(x=0, 0.1, 0.2, 0.3) on the titanium substrate were prepared by thermal decomposition of a chloride precursor mixture. Surface morphology and microstructure of the coatings were investigated by Scanning electron microscopy(SEM), Field emission scanning electron microscopy(FE-SEM) and X-ray diffraction(XrD) analysis. Systematic study of electrochemical properties of these coatings was performed by cyclic voltammetry(CV) and polarization measurements. The corrosion behavior of the coatings was evaluated under accelerated conditions(j=2 A cm-2) in acidic electrolyte. The role of iridium oxide admixture in the change of electrocatalytic activity and stability of ru0.6Ti0.4O2coating was discussed. Small addition of IrO2can improve the stability of the ruO2+TiO2mixed oxide, while the electrocatalytic activity for oxygen evolution reaction(OEr) is decreased. The shift of redox potentials for ru0.6Ti0.4O2electrode that is slightly activated with IrO2and improvement in the stability can be attributed to the synergetic effect of mixed oxide formation.

关键词： Coating Electrocatalyst Electrode Oxygen evolution ruthenium oxide Iridium oxide