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Optimum amount of additive mass in scaling of operational mode shapes
Khatibi, M.M.,Ashory, M.R.,Albooyeh, A.R. Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.5
Recently, identification of modal parameters using the response only data has attracted considerable attention particularly where the classic modal testing methods is difficult to conduct. One drawback of the response only data, also known as Operational Modal Analysis (OMA), is that only the unscaled mode shapes can be obtained which restricts the applications of OMA. The Mass change method is a usual way to scale the operational mode shapes. In this article a new method is proposed to optimize the additive mass for scaling of the unscaled mode shapes from OMA for which a priori knowledge of the Finite Element model of structure is required. It is shown that the total error of the scaled mode shapes is minimized using the proposed method. The method is validated using a numerical case study of a beam. Moreover, the experimental results of a clamped-clamped beam demonstrate the applicability of the method.
Optimum amount of additive mass in scaling of operational mode shapes
M.M. Khatibi,M.R. Ashory,A.R. Albooyeh 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.5
Recently, identification of modal parameters using the response only data has attracted considerable attention particularly where the classic modal testing methods is difficult to conduct. One drawback of the response only data, also known as Operational Modal Analysis (OMA), is that only the unscaled mode shapes can be obtained which restricts the applications of OMA. The Mass change method is a usual way to scale the operational mode shapes. In this article a new method is proposed to optimize the additive mass for scaling of the unscaled mode shapes from OMA for which a priori knowledge of the Finite Element model of structure is required. It is shown that the total error of the scaled mode shapes is minimized using the proposed method. The method is validated using a numerical case study of a beam. Moreover, the experimental results of a clamped-clamped beam demonstrate the applicability of the method.
Software Defect Prediction using a High Performance Neural Network
Mohamad Mahdi Askari,Vahid Khatibi Bardsiri 보안공학연구지원센터 2014 International Journal of Software Engineering and Vol.8 No.12
Predicting the existing defects in software products is one of the considerable issues in software engineering that contributes a lot toward saving time in software production and maintenance process. In fact, finding the desirable models for predicting software defects has nowadays turned into one of the main goals of software engineers. Since intricacies and restrictions of software development are increasing and unwilling consequences such as failure and errors decrease software quality and customer satisfaction, producing error-free software is very difficult and challenging. One of the efficient models in this field is multilayer neural network with proper learning algorithm. Many of the learning algorithms suffer from extra overfitting in the learning datasets. In this article, setting multilayer neural network method was used in order to improve and increase generalization capability of learning algorithm in predicting software defects. In order to solve the existing problems, a new method is proposed by developing new learning methods based on support vector machine principles and using evolutionary algorithms. The proposed method prevents from overfitting issue and maximizes classification margin. Efficiency of the proposed algorithm has been validated against 11 machine learning models and statistical methods within 3 NASA datasets. Results reveal that the proposed algorithm provides higher accuracy and precision compared to the other models.
Fabrication of a Flexible Si-cotton Filter Membrane for Efficient Hot Oil/Hot Water Separation
Leila Ghorbani,Ali Khatibi,Saravana B. Basuvalingam,Daniela Caschera,Babak Shokri 한국섬유공학회 2022 Fibers and polymers Vol.23 No.3
Increasing oily industrial waste water at room and high temperatures has become one of the most significantthreats to the global ecosystem. Finding a suitable method for separating hot-oil/water pollution with an appropriate filter ishighly necessary to effectively solve this problem. In this study, high-temperature oil/water separation was achieved using asilicon-modified textile (Si-cotton) as a filter, which was fabricated using polydimethylsiloxane (PDMS) solution as theprecursor and through plasma polymerization. The plasma polymerization generated a uniform micro and nanoscalehierarchical structure on the Si-cotton surface. Furthermore, XPS and FT-IR analysis showed the lowering of the O/C ratio onthe Si-cotton surface with respect to the pristine textile, and the presence of silicon on the Si-cotton surface after the plasmaprocess. The results of these factors can be critical in making the final hydrophobic/oleophilic behaviour of the textile. Moreimportantly, the Si-cotton membrane was tested for the separation process of hot oil/hot water mixture, which showed anacceptable efficiency even after fifteen separation cycles. The findings offered a two-step method, efficient and green, whichwas capable of working well even at a high temperature, to fabricate a flexible and scalable Si-cotton textile filter forreducing the necessity of additional and complicated cooling processes in the presence of high-temperature oil/water mixture.
Gigacycle Fatigue Crack Initiation in Cr-Mo Prealloy Sintered Steel
Xu Chen,Danninger Herbert,Khatibi Golta,Weiss Brigitte 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
Crack initiation and short crack propagation was studied on the polished notched surfaces of Cr-Mo prealloy sintered steels with 7.35 sintered density. An ultrasonic resonance test system operating in push-pull mode at 20 kHz and R=-1 was used. It showed that crack initiation took place in several places, small cracks growing oriented to the local pore structure rather than to stress orientation. Their growth rate is markedly higher than the corresponding one of long cracks. Finally, several microcracks join to form a dominant crack.
Beeta Tavana,Alireza Khatibi,Saeed Jafarkhani,Payam Zahedi,Mohammad Hossein Zamani,Seyed Hassan Jafari,Mohammad Najafi 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.124 No.-
Clarithromycin (CLR)-loaded poly (e-caprolactone) (PCL) nanoparticles (NPs) were synthesized usingmicrofluidics (MF) with square-shaped (MF1), and three-channel (MF2), geometries as well as conventionalbulk mixing (BM). Based on Comsol simulation results of MF chips, the flow rate ratio, nonsolventphase flow rate, and polymer solution concentration were optimized 0.05, 50 mL h1, and 0.2(%w/v), respectively; thereby, representing MF1 geometry with highest homogenous mixing. Characterization studies indicated that MF1-based NPs possessed smaller average diameter (91 nm),narrower polydispersity index (0.13) and higher zeta potential (-44 mV) compared to those NPs synthesizedby MF2 and BM methods. Moreover, MF1-aided synthesis of NPs exhibited the encapsulation efficiencyof approximately 81% and loading capacity of around 13%. Investigating CLR release behavior atdifferent pHs also demonstrated that the MF1-based NPs experienced the most controlled release, followedthe Fickian diffusion mechanism. The controlled release of MF1-based NPs was confirmed by evaluatingtheir inhibitory effect against specific cytokines on BEAS-2B as bronchitis cell line via a series ofin vitro experiments including real time-polymerase chain reaction and flow cytometry. Eventually, theantibacterial properties of the samples were studied on two prevalent bacterial strains and the obtainedobservations revealed that MF1-based NPs encompassed the best performance in controlled release ofCLR with respect to the other samples.