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This study focuses on the dynamic modelling and analysis of the wind turbine blades made of multiple layers of fibre reinforced composites and core materials. For this purpose, a novel three-dimensional analytical straight beam model for blades is formulated. This model assumes that the beam is made of functionally graded material (FGM) and has a variable and asymmetrical cross section. In this model, the blades are assumed to be thin, slender and long with a relatively straight axis. They have two main parts, namely the core and the shell. The so-called core consists of a lightweight isotropic foam material, which also adds significant damping to the system. The core material is covered by the shell, which is modelled using homogenous and orthotropic material assumptions as the structure is reinforced with continuous fibres. Therefore, the blades are modelled under a straight beam with varying cross-section assumptions, in which the effective elastic properties are acquired by homogenizing the cross section. The beam formulation for modelling the system is performed both analytically and numerically with the finite element method. The results of both methods are in well agreement. The maximum deviation between the results is found below 4%.
Mertol Tüfekci; Ömer Ekim Genel; Ali Tatar; Ekrem Tüfekci. Dynamic Analysis of Composite Wind Turbine Blades as Beams: An Analytical and Numerical Study. Vibration 2020, 4, 1 -15.
AMA StyleMertol Tüfekci, Ömer Ekim Genel, Ali Tatar, Ekrem Tüfekci. Dynamic Analysis of Composite Wind Turbine Blades as Beams: An Analytical and Numerical Study. Vibration. 2020; 4 (1):1-15.
Chicago/Turabian StyleMertol Tüfekci; Ömer Ekim Genel; Ali Tatar; Ekrem Tüfekci. 2020. "Dynamic Analysis of Composite Wind Turbine Blades as Beams: An Analytical and Numerical Study." Vibration 4, no. 1: 1-15.
This study investigated the failure of the roof, with steel truss construction, of a factory building in Tekirdag in the northwestern part of Turkey. The failure occurred under hefty weather conditions including lightning strikes, heavy rain, and fierce winds. In order to interpret the reason for the failure, the effects of different combinations of factors on the design and dimensioning of the roof were studied. Finite element analysis, using the commercial software Abaqus (Dassault Systèmes, Vélizy-Villacoublay, France), was performed several times under different assumptions and considering different factors with the aim of determining the dominant factors that were responsible for the failure. Each loading condition gives out a characteristic form of failure. The scenario with the most similar form of failure to the real collapse is considered as the most likely scenario of failure. In addition, the factors included in this scenario are expected to be the responsible factors for the partial collapse of the steel truss structure.
Mertol Tüfekci; Ekrem Tüfekci; Adnan Dikicioğlu. Numerical Investigation of the Collapse of a Steel Truss Roof and a Probable Reason of Failure. Applied Sciences 2020, 10, 7769 .
AMA StyleMertol Tüfekci, Ekrem Tüfekci, Adnan Dikicioğlu. Numerical Investigation of the Collapse of a Steel Truss Roof and a Probable Reason of Failure. Applied Sciences. 2020; 10 (21):7769.
Chicago/Turabian StyleMertol Tüfekci; Ekrem Tüfekci; Adnan Dikicioğlu. 2020. "Numerical Investigation of the Collapse of a Steel Truss Roof and a Probable Reason of Failure." Applied Sciences 10, no. 21: 7769.
This study investigates the failure of a roof with steel truss construction of a factory building in Tekirdag in North-western part of Turkey. The failure occurred under hefty weather conditions including thunderbolt, lightning strikes, heavy rain and fierce winds. In order to interpret the reason for the failure, the effects of different combinations of factors on the design and dimensioning of the roof are checked. Therefore, finite element analysis is performed several times under different assumptions and considering different factors aiming to determine the dominant ones that are responsible for the failure using the commercial software Abaqus (Dassault Systèmes, Vélizy-Villacoublay, France). Each loading condition gives out a characteristic form of failure. The scenario with the most similar form of failure to the real collapse is considered as the most likely scenario of failure. Also, the factors included in this scenario are expected to be the responsible factors for the partial collapse of the steel truss structure.
Mertol Tufekci; Ekrem Tüfekci; Adnan Dikicioğlu. Numerical Investigation of the Collapse of the Steel Truss Roof and a Probable Reason of Failure. 2020, 1 .
AMA StyleMertol Tufekci, Ekrem Tüfekci, Adnan Dikicioğlu. Numerical Investigation of the Collapse of the Steel Truss Roof and a Probable Reason of Failure. . 2020; ():1.
Chicago/Turabian StyleMertol Tufekci; Ekrem Tüfekci; Adnan Dikicioğlu. 2020. "Numerical Investigation of the Collapse of the Steel Truss Roof and a Probable Reason of Failure." , no. : 1.
The statics of fully deformable parabolic arches affected by a small crack at opposite sides of a damaged cross section is studied. The finite governing equations are linearized; the mechanical response for ‘small’ displacements and rotation is assumed. The effect of the crack is modelled by springs with stiffnesses calculated through linear elastic fracture mechanics. Closed-form exact static solutions are found under suitable boundary and continuity conditions. The effects of the crack position along the arch axis, its depth, and location on the cross section for different loading and boundary conditions are investigated and commented. The possibility of using these solutions in structural identification is discussed.
Ugurcan Eroglu; Achille Paolone; Giuseppe Ruta; Ekrem Tüfekci. Exact closed-form static solutions for parabolic arches with concentrated damage. Archive of Applied Mechanics 2019, 90, 673 -689.
AMA StyleUgurcan Eroglu, Achille Paolone, Giuseppe Ruta, Ekrem Tüfekci. Exact closed-form static solutions for parabolic arches with concentrated damage. Archive of Applied Mechanics. 2019; 90 (4):673-689.
Chicago/Turabian StyleUgurcan Eroglu; Achille Paolone; Giuseppe Ruta; Ekrem Tüfekci. 2019. "Exact closed-form static solutions for parabolic arches with concentrated damage." Archive of Applied Mechanics 90, no. 4: 673-689.
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U Eroglu; G Ruta; E Tufekci. Natural frequencies of parabolic arches with a single crack on opposite cross-section sides. Journal of Vibration and Control 2019, 25, 1313 -1325.
AMA StyleU Eroglu, G Ruta, E Tufekci. Natural frequencies of parabolic arches with a single crack on opposite cross-section sides. Journal of Vibration and Control. 2019; 25 (7):1313-1325.
Chicago/Turabian StyleU Eroglu; G Ruta; E Tufekci. 2019. "Natural frequencies of parabolic arches with a single crack on opposite cross-section sides." Journal of Vibration and Control 25, no. 7: 1313-1325.
Ugurcan Eroglu; Ekrem Tüfekci. Some closed-form solutions for buckling of straight beams with varying cross-section by Variational Iteration Method with Generalized Lagrange Multipliers. International Journal of Engineering and Applied Sciences 2018, 10, 159 -175.
AMA StyleUgurcan Eroglu, Ekrem Tüfekci. Some closed-form solutions for buckling of straight beams with varying cross-section by Variational Iteration Method with Generalized Lagrange Multipliers. International Journal of Engineering and Applied Sciences. 2018; 10 (3):159-175.
Chicago/Turabian StyleUgurcan Eroglu; Ekrem Tüfekci. 2018. "Some closed-form solutions for buckling of straight beams with varying cross-section by Variational Iteration Method with Generalized Lagrange Multipliers." International Journal of Engineering and Applied Sciences 10, no. 3: 159-175.
This study aims to derive a new finite element formulation for in-plane free vibrations of curved beams with arbitrary curvature, and cross-section variation. The stiffness matrix presented in this study are obtained from the exact solution of the static problem, considering the effects of axial extension, shear deformation. Using the exact solution for point loads, a consistent mass matrix is obtained, considering the effect of rotatory inertia. Numerous examples, related to the free vibrations of planar curved beams are solved to validate the presented approach. It is proved that presented formulation does not suffer from any locking phenomena. Circular beams with varying cross-section are investigated by assembling uniform elements. Parabolic, elliptic, and sinusoidal beams are examined by both using variable curvature elements, and assembling circular beam elements. This new formulation is thought to be an effective tool in structural analysis of curved beams.
Ugurcan Eroglu; Ekrem Tufekci. A new finite element formulation for free vibrations of planar curved beams. Mechanics Based Design of Structures and Machines 2018, 46, 730 -750.
AMA StyleUgurcan Eroglu, Ekrem Tufekci. A new finite element formulation for free vibrations of planar curved beams. Mechanics Based Design of Structures and Machines. 2018; 46 (6):730-750.
Chicago/Turabian StyleUgurcan Eroglu; Ekrem Tufekci. 2018. "A new finite element formulation for free vibrations of planar curved beams." Mechanics Based Design of Structures and Machines 46, no. 6: 730-750.
Andrea Apuzzo; Amir Asadi; Serhan A. Aya; Wiyao Azoti; Raffaele Barretta; Marko Čanađija; Francesco Marotti De Sciarra; Ahmed Elmarakbi; Francesco Fabbrocino; Michele Giordano; Kyriaki Kalaitzidou; Raimondo Luciano; Alfonso Martone; Francesco Giuseppe Morabito; Maria R. Ricciardi; Enrico Russo; Pietro Russo; Giuseppe Ruta; Ekrem Tufekci. Contributors. Experimental Characterization, Predictive Mechanical and Thermal Modeling of Nanostructures and their Polymer Composites 2018, 1 .
AMA StyleAndrea Apuzzo, Amir Asadi, Serhan A. Aya, Wiyao Azoti, Raffaele Barretta, Marko Čanađija, Francesco Marotti De Sciarra, Ahmed Elmarakbi, Francesco Fabbrocino, Michele Giordano, Kyriaki Kalaitzidou, Raimondo Luciano, Alfonso Martone, Francesco Giuseppe Morabito, Maria R. Ricciardi, Enrico Russo, Pietro Russo, Giuseppe Ruta, Ekrem Tufekci. Contributors. Experimental Characterization, Predictive Mechanical and Thermal Modeling of Nanostructures and their Polymer Composites. 2018; ():1.
Chicago/Turabian StyleAndrea Apuzzo; Amir Asadi; Serhan A. Aya; Wiyao Azoti; Raffaele Barretta; Marko Čanađija; Francesco Marotti De Sciarra; Ahmed Elmarakbi; Francesco Fabbrocino; Michele Giordano; Kyriaki Kalaitzidou; Raimondo Luciano; Alfonso Martone; Francesco Giuseppe Morabito; Maria R. Ricciardi; Enrico Russo; Pietro Russo; Giuseppe Ruta; Ekrem Tufekci. 2018. "Contributors." Experimental Characterization, Predictive Mechanical and Thermal Modeling of Nanostructures and their Polymer Composites , no. : 1.
Nanobeams are widely used as a structural element for nanodevices and nanomachines. The development of nanosized machines depends on proper understanding of mechanical behavior of these nanosized beam elements. In this chapter, the static and dynamic behavior of a curved planar nanobeam having variable curvature and cross-section is investigated. The nonlocal constitutive equations of Eringen are written in cylindrical coordinates and then implemented into the classical beam equations. Analytical exact solutions for static problems are obtained by using the initial value method. The equations of free vibration are derived by means of d’Alembert principle. The nonlocal theory and the equations presented in this chapter form the basis for the study of static and dynamic analysis of nanobeams. Instead of using classical beam theory, using nonlocal elasticity theory reveals the size effects, which is significant to understand the mechanical behavior of nanobeams.
Ekrem Tufekci; Serhan A. Aya. Nonlocal Continuum Modeling of Curved Nanostructures. Experimental Characterization, Predictive Mechanical and Thermal Modeling of Nanostructures and their Polymer Composites 2018, 101 -158.
AMA StyleEkrem Tufekci, Serhan A. Aya. Nonlocal Continuum Modeling of Curved Nanostructures. Experimental Characterization, Predictive Mechanical and Thermal Modeling of Nanostructures and their Polymer Composites. 2018; ():101-158.
Chicago/Turabian StyleEkrem Tufekci; Serhan A. Aya. 2018. "Nonlocal Continuum Modeling of Curved Nanostructures." Experimental Characterization, Predictive Mechanical and Thermal Modeling of Nanostructures and their Polymer Composites , no. : 101-158.
Ugurcan Eroglu; Ekrem Tufekci. Small-Amplitude free vibrations of straight beams subjected to large displacements and rotation. Applied Mathematical Modelling 2018, 53, 223 -241.
AMA StyleUgurcan Eroglu, Ekrem Tufekci. Small-Amplitude free vibrations of straight beams subjected to large displacements and rotation. Applied Mathematical Modelling. 2018; 53 ():223-241.
Chicago/Turabian StyleUgurcan Eroglu; Ekrem Tufekci. 2018. "Small-Amplitude free vibrations of straight beams subjected to large displacements and rotation." Applied Mathematical Modelling 53, no. : 223-241.
In this paper, a procedure based on the transfer matrix method for obtaining the exact solution to the equations of free vibration of damaged frame structures, considering the effects of axial extension, shear deformation, rotatory inertia, and all compliance components arising due to the presence of a crack, is presented. The crack is modeled by a rotational and/or translational spring based on the concept of linear elastic fracture mechanics. Only the in-plane motion of planar structures is considered. The formulation is validated through some examples existing in the literature. Additionally, the mode shapes and natural frequencies of a frame with pitched roof are provided. The variation of natural frequencies with respect to the crack location is presented. It is concluded that considering the axial compliance, and axial-bending coupling due to the presence of a crack results in different dynamic characteristics, which should be considered for problems where high precision is required, such as for the crack identification problems.
Ugurcan Eroglu; Ekrem Tufekci. Free Vibration of Damaged Frame Structures Considering the Effects of Axial Extension, Shear Deformation and Rotatory Inertia: Exact Solution. International Journal of Structural Stability and Dynamics 2017, 17, 1750111 .
AMA StyleUgurcan Eroglu, Ekrem Tufekci. Free Vibration of Damaged Frame Structures Considering the Effects of Axial Extension, Shear Deformation and Rotatory Inertia: Exact Solution. International Journal of Structural Stability and Dynamics. 2017; 17 (10):1750111.
Chicago/Turabian StyleUgurcan Eroglu; Ekrem Tufekci. 2017. "Free Vibration of Damaged Frame Structures Considering the Effects of Axial Extension, Shear Deformation and Rotatory Inertia: Exact Solution." International Journal of Structural Stability and Dynamics 17, no. 10: 1750111.
Ugurcan Eroglu; Ekrem Tufekci. Crack modeling and identification in curved beams using differential evolution. International Journal of Mechanical Sciences 2017, 131-132, 435 -450.
AMA StyleUgurcan Eroglu, Ekrem Tufekci. Crack modeling and identification in curved beams using differential evolution. International Journal of Mechanical Sciences. 2017; 131-132 ():435-450.
Chicago/Turabian StyleUgurcan Eroglu; Ekrem Tufekci. 2017. "Crack modeling and identification in curved beams using differential evolution." International Journal of Mechanical Sciences 131-132, no. : 435-450.
Serhan Aydin Aya; Ekrem Tufekci. Modeling and analysis of out-of-plane behavior of curved nanobeams based on nonlocal elasticity. Composites Part B: Engineering 2017, 119, 184 -195.
AMA StyleSerhan Aydin Aya, Ekrem Tufekci. Modeling and analysis of out-of-plane behavior of curved nanobeams based on nonlocal elasticity. Composites Part B: Engineering. 2017; 119 ():184-195.
Chicago/Turabian StyleSerhan Aydin Aya; Ekrem Tufekci. 2017. "Modeling and analysis of out-of-plane behavior of curved nanobeams based on nonlocal elasticity." Composites Part B: Engineering 119, no. : 184-195.
In this study, a new finite element formulation is presented for straight beams with an edge crack, including the effects of shear deformation, and rotatory inertia. The main purpose of the study is to present a more accurate formulation to improve the beam models used in crack detection problems. Stiffness matrix, consistent load vector, and mass matrix of a beam element is obtained using the exact solution of the governing equations. The formulation for frame structures is also presented. Crack is modelled utilizing from the concepts of linear elastic fracture mechanics. Several numerical examples existing in the literature related to the vibrations of such structures are solved to validate the proposed model. Additionally, an experimental modal analysis is performed to see the superiority of the present method for high modes of vibration, which are generally not taken into account in crack detection problems. The inverse problem is also solved using a well – known optimization technique called genetic algorithms. Effects of shear deformation, rotatory inertia, and number of natural frequencies considered, on the accuracy of the estimation of crack parameters are investigated. It is found that considering more number of frequencies yields better estimation of crack parameters, but require a better modelling of the dynamics of the beam. Therefore, the present formulation is found to be an essential tool in crack detection problems.
Ugurcan Eroglu; Ekrem Tufekci. Exact solution based finite element formulation of cracked beams for crack detection. International Journal of Solids and Structures 2016, 96, 240 -253.
AMA StyleUgurcan Eroglu, Ekrem Tufekci. Exact solution based finite element formulation of cracked beams for crack detection. International Journal of Solids and Structures. 2016; 96 ():240-253.
Chicago/Turabian StyleUgurcan Eroglu; Ekrem Tufekci. 2016. "Exact solution based finite element formulation of cracked beams for crack detection." International Journal of Solids and Structures 96, no. : 240-253.
Highlights•Equations of the nonlocal elasticity theory are arranged in cylindrical coordinates.•These equations are implemented in the beam theory.•Nonlocal equations of curved beams are solved exactly by using initial value method.•Several examples are solved and the results are obtained analytically. AbstractIn this paper, out-of-plane static behavior of circular nanobeams with point loads is investigated. Inclusion of small length scales such as lattice spacing between atoms, surface properties, grain size etc. are considered in the analysis by employing Eringen’s nonlocal elasticity theory in the formulations. The nonlocal equations are arranged in cylindrical coordinates and applied to the beam theory. The effect of shear deformation is considered. The governing differential equations are solved exactly by using the initial value method. The displacements, rotation angle about the normal and tangential axes and the force resultants are established and the analytical expressions are presented. The predicted trends of the size effect at the nano scale agree with those given in the experiments. The results can be used for designing nanoelectromechanical systems (NEMS) where the curved nanobeams are used as a basic component.
Ekrem Tufekci; Serhan A. Aya. A nonlocal beam model for out-of-plane static analysis of circular nanobeams. Mechanics Research Communications 2016, 76, 11 -23.
AMA StyleEkrem Tufekci, Serhan A. Aya. A nonlocal beam model for out-of-plane static analysis of circular nanobeams. Mechanics Research Communications. 2016; 76 ():11-23.
Chicago/Turabian StyleEkrem Tufekci; Serhan A. Aya. 2016. "A nonlocal beam model for out-of-plane static analysis of circular nanobeams." Mechanics Research Communications 76, no. : 11-23.
A unified formulation for static behavior of nonlocal curved beams curved nanobeams;nonlocal elasticity;in-plane statics;exact solution;initial value method; Nanobeams are widely used as a structural element for nanodevices and nanomachines. The development of nano-sized machines depends on proper understanding of mechanical behavior of these nano-sized beam elements. Small length scales such as lattice spacing between atoms, surface properties, grain size etc. are need to be considered when applying any classical continuum model. In this study, Eringen's nonlocal elasticity theory is incorporated into classical beam model considering the effects of axial extension and the shear deformation to capture unique static behavior of the nanobeams under continuum mechanics theory. The governing differential equations are obtained for curved beams and solved exactly by using the initial value method. Circular uniform beam with concentrated loads are considered. The displacements, slopes and the stress resultants are obtained analytically. A detailed parametric study is conducted to examine the effect of the nonlocal parameter, mechanical loadings, opening angle, boundary conditions, and slenderness ratio on the static behavior of the nanobeam.
Ekrem Tufekci; Serhan A. Aya; Olcay Oldac. A unified formulation for static behavior of nonlocal curved beams. Structural Engineering and Mechanics 2016, 59, 475 -502.
AMA StyleEkrem Tufekci, Serhan A. Aya, Olcay Oldac. A unified formulation for static behavior of nonlocal curved beams. Structural Engineering and Mechanics. 2016; 59 (3):475-502.
Chicago/Turabian StyleEkrem Tufekci; Serhan A. Aya; Olcay Oldac. 2016. "A unified formulation for static behavior of nonlocal curved beams." Structural Engineering and Mechanics 59, no. 3: 475-502.
Despite being one of the simplest structural elements, beams are used in many engineering structures. One of the most common methods to analyze and design such structures is the finite element method. Even though many different shape functions for finite beam elements have been offered, still there is a need for a beam formulation that does not suffer from numerical errors, locking problems, and yields accurate results with minimum number of elements. For this reason, in this study, a finite curved beam element formulation is developed based on the exact analytical solution of the governing differential equation of planar curved beams. The axial extension and shear deformation effects are considered in the formulation. Since the stiffness matrix and consistent load vector are obtained from the exact solution, there is no locking problem with the formulation. Many numerical examples are solved to indicate the performance of the proposed element with any loading and boundary conditions. Beams with varying curvature and varying cross section are investigated along with the circular beams with constant cross section. The results show that the element formulation is superior to other elements in the literature with accuracy and wide range of applicability for arbitrarily shaped curved beams.
Ekrem Tufekci; Ugurcan Eroglu; Serhan Aydin Aya. A new two-noded curved beam finite element formulation based on exact solution. Engineering with Computers 2016, 33, 261 -273.
AMA StyleEkrem Tufekci, Ugurcan Eroglu, Serhan Aydin Aya. A new two-noded curved beam finite element formulation based on exact solution. Engineering with Computers. 2016; 33 (2):261-273.
Chicago/Turabian StyleEkrem Tufekci; Ugurcan Eroglu; Serhan Aydin Aya. 2016. "A new two-noded curved beam finite element formulation based on exact solution." Engineering with Computers 33, no. 2: 261-273.
Serhan Aydin Aya; Olcay Oldac; Ekrem Tufekci. A Nonlocal Elasticity Approach for the In-Plane Static Analysis of Nanoarches. Proceedings of the 2nd World Congress on New Technologies 2016, 1 .
AMA StyleSerhan Aydin Aya, Olcay Oldac, Ekrem Tufekci. A Nonlocal Elasticity Approach for the In-Plane Static Analysis of Nanoarches. Proceedings of the 2nd World Congress on New Technologies. 2016; ():1.
Chicago/Turabian StyleSerhan Aydin Aya; Olcay Oldac; Ekrem Tufekci. 2016. "A Nonlocal Elasticity Approach for the In-Plane Static Analysis of Nanoarches." Proceedings of the 2nd World Congress on New Technologies , no. : 1.
Serhan Aydin Aya; Ekrem Tufekci. Out-of-Plane Static Analysis of Nanoarches Using Eringen’s Nonlocal Elasticity Theory. Proceedings of the 2nd World Congress on New Technologies 2016, 1 .
AMA StyleSerhan Aydin Aya, Ekrem Tufekci. Out-of-Plane Static Analysis of Nanoarches Using Eringen’s Nonlocal Elasticity Theory. Proceedings of the 2nd World Congress on New Technologies. 2016; ():1.
Chicago/Turabian StyleSerhan Aydin Aya; Ekrem Tufekci. 2016. "Out-of-Plane Static Analysis of Nanoarches Using Eringen’s Nonlocal Elasticity Theory." Proceedings of the 2nd World Congress on New Technologies , no. : 1.
This paper presents the derivation of the nonlocal equations for curved beams with varying curvature and cross-section. Eringen’s nonlocal constitutive equations are rewritten in cylindrical coordinates and implemented into the classical beam equations considering the effects of axial extension and the shear deformation. Varying distributed loads are also considered in the equations. The governing differential equations of an arbitrary curved beam bearing variable distributed loads are solved exactly by using the initial value method. The displacements, rotation angle about the binormal axis and the force resultants are obtained analytically. The nonlocal equations include the length scale parameter which is also known as nonlocal parameter. Several numerical examples are solved to emphasize the effect of the length scale parameter. A parametric study is also performed to point out the effects of the slenderness ratio, opening angle, loading and boundary conditions and also axial and shear deformations on the static behavior of the beam.
Ekrem Tufekci; Serhan Aydin Aya; Olcay Oldac. In-Plane Static Analysis of Nonlocal Curved Beams with Varying Curvature and Cross-Section. International Journal of Applied Mechanics 2016, 8, 1650010 .
AMA StyleEkrem Tufekci, Serhan Aydin Aya, Olcay Oldac. In-Plane Static Analysis of Nonlocal Curved Beams with Varying Curvature and Cross-Section. International Journal of Applied Mechanics. 2016; 8 (1):1650010.
Chicago/Turabian StyleEkrem Tufekci; Serhan Aydin Aya; Olcay Oldac. 2016. "In-Plane Static Analysis of Nonlocal Curved Beams with Varying Curvature and Cross-Section." International Journal of Applied Mechanics 8, no. 1: 1650010.