When analyzing the strength of large structures, the stiffness of the foundation, on which the structure is placed, might significantly affect the numerical results. In this paper, a finite element approach to estimate the foundation stiffness as an inverse problem is proposed, where the target large structure is placed on the elastic foundation that are modeled as groups of one-dimensional spring elements in parallel. The magnitude of the spring constant that represents the foundation stiffness can exactly be calculated algebraically by use of the same number of measured surface deflections. In the numerical analyses, unknowns are the diagonal components in the global stiffness matrix that include the aforementioned spring constants. The validity and the accuracy of the proposed numerical method are verified by comparing the numerical results to the exact solutions for bending problems of a cantilever supported by a single spring element.
{"title":"Identification of the Foundation Stiffness of Large Structure as an Inverse Problem","authors":"T. Fukuoka, M. Nomura, Yuyong Zhao","doi":"10.1299/JCST.2.578","DOIUrl":"https://doi.org/10.1299/JCST.2.578","url":null,"abstract":"When analyzing the strength of large structures, the stiffness of the foundation, on which the structure is placed, might significantly affect the numerical results. In this paper, a finite element approach to estimate the foundation stiffness as an inverse problem is proposed, where the target large structure is placed on the elastic foundation that are modeled as groups of one-dimensional spring elements in parallel. The magnitude of the spring constant that represents the foundation stiffness can exactly be calculated algebraically by use of the same number of measured surface deflections. In the numerical analyses, unknowns are the diagonal components in the global stiffness matrix that include the aforementioned spring constants. The validity and the accuracy of the proposed numerical method are verified by comparing the numerical results to the exact solutions for bending problems of a cantilever supported by a single spring element.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132762804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A preliminary numerical simulation of the microscopic two-phase fluid motion on a solid surface was conducted using an interface-tracking method based on the phase-field model (PFM). Two variations of the lattice Boltzmann method (LBM) based on fictitious particle kinematics are proposed for solving diffuse-interface advection equations which were revised to improve volume-of-fluid conservation in the PFM simulations. The major findings are as follows: (1) the interface-tracking method accurately predicted the capillary force effect on dynamic two-phase fluid systems with a high density ratio between parallel plates; (2) the initial shape and volume of the two-phase fluid were retained adequately in linear translation with the use of the LBMs. These results proved that the PFM-based method and the LBM-based advection schemes can be used for simulating two-phase fluid motions in various macroand microfluidics problems for devices, machineries and higher-throughput microdevice fabrication processes.
{"title":"Phase-Field Model-Based Simulation of Motions of a Two-Phase Fluid on Solid Surface","authors":"N. Takada, J. Matsumoto, S. Matsumoto","doi":"10.1299/JCST.7.322","DOIUrl":"https://doi.org/10.1299/JCST.7.322","url":null,"abstract":"A preliminary numerical simulation of the microscopic two-phase fluid motion on a solid surface was conducted using an interface-tracking method based on the phase-field model (PFM). Two variations of the lattice Boltzmann method (LBM) based on fictitious particle kinematics are proposed for solving diffuse-interface advection equations which were revised to improve volume-of-fluid conservation in the PFM simulations. The major findings are as follows: (1) the interface-tracking method accurately predicted the capillary force effect on dynamic two-phase fluid systems with a high density ratio between parallel plates; (2) the initial shape and volume of the two-phase fluid were retained adequately in linear translation with the use of the LBMs. These results proved that the PFM-based method and the LBM-based advection schemes can be used for simulating two-phase fluid motions in various macroand microfluidics problems for devices, machineries and higher-throughput microdevice fabrication processes.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116263735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recent earth environment problem is accelerating rapid popularization of hybrid or electric vehicles replacing conventional vehicles powered by fossil fuels. The electric vehicles don’t need exhaust pipes and power train system like propeller shaft under the floor, so their floors can be flattened. Flat floor may also contribute to crash safety and suitable structural material for this purpose will be required. In this paper, authors studied optimal shape to improve energy absorption ability of truss core panel which the usage is considered as vehicle structure. Effective optimization technique especially for nonlinear problem, Radial Basis Function (RBF) network with Response Surface Method (RSM) is adopted in the paper and applied to optimize the shape of truss core panel. Energy absorption quantities for x, y, and z directions were treated as independent objectives and multi-objective optimization was performed. A commercial preprocessor HyperMorph is used for morphing, explicit FEM software LS-DYNA is used to solve crash analysis and LS-OPT is used to handle multiple jobs and optimization process. As the result, 7.1 % of improvement for the energy absorption for the crash in x direction was achieved and Pareto curves for the objectives were obtained.
{"title":"Shape Optimization to Improve Impact Energy Absorption Ability of Truss Core Panel","authors":"Sunao Tokura, I. Hagiwara","doi":"10.1299/JCST.5.1","DOIUrl":"https://doi.org/10.1299/JCST.5.1","url":null,"abstract":"Recent earth environment problem is accelerating rapid popularization of hybrid or electric vehicles replacing conventional vehicles powered by fossil fuels. The electric vehicles don’t need exhaust pipes and power train system like propeller shaft under the floor, so their floors can be flattened. Flat floor may also contribute to crash safety and suitable structural material for this purpose will be required. In this paper, authors studied optimal shape to improve energy absorption ability of truss core panel which the usage is considered as vehicle structure. Effective optimization technique especially for nonlinear problem, Radial Basis Function (RBF) network with Response Surface Method (RSM) is adopted in the paper and applied to optimize the shape of truss core panel. Energy absorption quantities for x, y, and z directions were treated as independent objectives and multi-objective optimization was performed. A commercial preprocessor HyperMorph is used for morphing, explicit FEM software LS-DYNA is used to solve crash analysis and LS-OPT is used to handle multiple jobs and optimization process. As the result, 7.1 % of improvement for the energy absorption for the crash in x direction was achieved and Pareto curves for the objectives were obtained.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116453438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"FEM Simulation of Coupled Flow and Bed Morphodynamic Interactions due to Sediment Transport Phenomena","authors":"J. Camata, R. Elias, A. Coutinho","doi":"10.1299/JCST.7.306","DOIUrl":"https://doi.org/10.1299/JCST.7.306","url":null,"abstract":"","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116759627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A new method of Adaptive Plan system with Genetic Algorithm called APGA is proposed to reduce a large amount of calculation cost and to improve a stability in convergence to an optimal solution for multi-peak optimization problems with multidimensions. This is an approach that combines the global search ability of Genetic Algorithm (GA) and the local search ability of Adaptive Plan (AP). The APGA differs from GAs in handling design variable vectors (DVs). GAs generally encode DVs into genes and handle them through GA operators. However, the APGA encodes control variable vectors (CVs) of AP, which searches for local optimum, into its genes. CVs determine the global behavior of AP, and DVs are handled by AP in the optimization process of APGA. In this paper, we introduce some strategies using APGA to solve a huge scale of optimization problem and to improve the convergence towards the optimal solution. These methodologies are applied to several benchmark functions with multi-dimensions to evaluate its performance. We confirmed satisfactory performance through various benchmark tests.
{"title":"Evolutionary Strategies of Adaptive Plan System with Genetic Algorithm","authors":"Hieu Pham, Sousuke Tooyama, H. Hasegawa","doi":"10.1299/JCST.6.129","DOIUrl":"https://doi.org/10.1299/JCST.6.129","url":null,"abstract":"A new method of Adaptive Plan system with Genetic Algorithm called APGA is proposed to reduce a large amount of calculation cost and to improve a stability in convergence to an optimal solution for multi-peak optimization problems with multidimensions. This is an approach that combines the global search ability of Genetic Algorithm (GA) and the local search ability of Adaptive Plan (AP). The APGA differs from GAs in handling design variable vectors (DVs). GAs generally encode DVs into genes and handle them through GA operators. However, the APGA encodes control variable vectors (CVs) of AP, which searches for local optimum, into its genes. CVs determine the global behavior of AP, and DVs are handled by AP in the optimization process of APGA. In this paper, we introduce some strategies using APGA to solve a huge scale of optimization problem and to improve the convergence towards the optimal solution. These methodologies are applied to several benchmark functions with multi-dimensions to evaluate its performance. We confirmed satisfactory performance through various benchmark tests.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114964988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, a simple and efficient boundary element method using a modal transformation is presented to solve a transient acoustic problem in the open space around a structure caused by the vibration due to the impact force on it. After the transient vibration of the structure is obtained by the finite element analysis, the velocity response of the surface of the structure is transformed to frequency domain. Transient acoustic pressures at points of interest are calculated as a combination of steady-state acoustic boundary element solutions under the velocity boundary conditions at discrete frequencies. However, high frequency terms exceeding an allowable frequency, which is decided from the boundary element mesh, are automatically omitted to obtain a stable solution while saving the computation time considerably. To get the boundary element solution effectively, a modal transformation using vibration modes of the structure is made to the boundary element matrices at each frequency, since the acoustic behavior on the surface of the structure is considered to be related deeply to that of the vibration. However, extra modes are added to express the acoustic field around the surface where displacements are fixed.Based on the present method, a boundary element transient acoustic analysis program, ASA/ACOUSTICS has been developed. Numerical examples are demonstrated.
{"title":"An Efficient Boundary Element Method Using a Modal Transformation for Transient Acoustic Problem","authors":"M. Tanabe, T. Deura, H. Okuda","doi":"10.1299/JCST.2.222","DOIUrl":"https://doi.org/10.1299/JCST.2.222","url":null,"abstract":"In this paper, a simple and efficient boundary element method using a modal transformation is presented to solve a transient acoustic problem in the open space around a structure caused by the vibration due to the impact force on it. After the transient vibration of the structure is obtained by the finite element analysis, the velocity response of the surface of the structure is transformed to frequency domain. Transient acoustic pressures at points of interest are calculated as a combination of steady-state acoustic boundary element solutions under the velocity boundary conditions at discrete frequencies. However, high frequency terms exceeding an allowable frequency, which is decided from the boundary element mesh, are automatically omitted to obtain a stable solution while saving the computation time considerably. To get the boundary element solution effectively, a modal transformation using vibration modes of the structure is made to the boundary element matrices at each frequency, since the acoustic behavior on the surface of the structure is considered to be related deeply to that of the vibration. However, extra modes are added to express the acoustic field around the surface where displacements are fixed.Based on the present method, a boundary element transient acoustic analysis program, ASA/ACOUSTICS has been developed. Numerical examples are demonstrated.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114638235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Seungchol Choi, Yasuyuki Yamamoto, S. Matsumoto, Tomoko Yamamoto
A MEMS-viscosity sensor with dual spiral structure has been developed based on a novel measurement method unlike traditional method for viscosity measurement. This viscosity sensor, passing completely through a silicon wafer using MEMS (Micro Electro Mechanical Systems) fabrication processing, was made up the spiral structure with a vibrating body and a sensing body. When a large deflection was generated toward each direction of the vibration body of spiral structure due to the applied external load, it can be the cause of performance deterioration of the MEMS-viscosity sensor. And the analytical methods were proposed to fine the deflections by a computational analysis using FEM (Finite Element Method). A computational analysis was carried out by coupled analysis using modal analysis method and harmonic response analysis assuming air environment. In the spiral model of the MEMS-viscosity sensor on which normal loads of Fz=100 [μN] and Fz=1000 [μN] were applied, the maximum resonance points occurred at about 1400[Hz] of 1st mode along with vertical direction (Z-direction) respectively. When Fz=1000 [μN] was applied, the maximum value of deflection was obtained about 3.0x10 [m] in vertical direction, but the normal load of more than Fz=1000 [μN] should be avoided for safety and reliability of this MEMS-viscosity sensor because the deflections of horizontal directions (X and Y-direction) were near to limit of the design values. We found that the deflections of horizontal direction were small enough to be negligible compared to the vertical direction, and the spiral structure can be stably maintained against less than Fz=1000 [μN] of the external load. We also found out the waviness phenomenon in the deflections along the spiral beam. As a solution of the waviness phenomenon in the spiral structure with rectangular shape beam, it seems that the spiral beam must be given so that the spiral radius is continuously compensated by using other beam shapes. It was demonstrated that the approach using computational analysis allows us to deduce visually the deflection of the spiral structure for viscosity sensor.
{"title":"Computational Analysis of a Spiral Vibrating Beam for the MEMS-Viscosity Sensor","authors":"Seungchol Choi, Yasuyuki Yamamoto, S. Matsumoto, Tomoko Yamamoto","doi":"10.1299/JCST.7.89","DOIUrl":"https://doi.org/10.1299/JCST.7.89","url":null,"abstract":"A MEMS-viscosity sensor with dual spiral structure has been developed based on a novel measurement method unlike traditional method for viscosity measurement. This viscosity sensor, passing completely through a silicon wafer using MEMS (Micro Electro Mechanical Systems) fabrication processing, was made up the spiral structure with a vibrating body and a sensing body. When a large deflection was generated toward each direction of the vibration body of spiral structure due to the applied external load, it can be the cause of performance deterioration of the MEMS-viscosity sensor. And the analytical methods were proposed to fine the deflections by a computational analysis using FEM (Finite Element Method). A computational analysis was carried out by coupled analysis using modal analysis method and harmonic response analysis assuming air environment. In the spiral model of the MEMS-viscosity sensor on which normal loads of Fz=100 [μN] and Fz=1000 [μN] were applied, the maximum resonance points occurred at about 1400[Hz] of 1st mode along with vertical direction (Z-direction) respectively. When Fz=1000 [μN] was applied, the maximum value of deflection was obtained about 3.0x10 [m] in vertical direction, but the normal load of more than Fz=1000 [μN] should be avoided for safety and reliability of this MEMS-viscosity sensor because the deflections of horizontal directions (X and Y-direction) were near to limit of the design values. We found that the deflections of horizontal direction were small enough to be negligible compared to the vertical direction, and the spiral structure can be stably maintained against less than Fz=1000 [μN] of the external load. We also found out the waviness phenomenon in the deflections along the spiral beam. As a solution of the waviness phenomenon in the spiral structure with rectangular shape beam, it seems that the spiral beam must be given so that the spiral radius is continuously compensated by using other beam shapes. It was demonstrated that the approach using computational analysis allows us to deduce visually the deflection of the spiral structure for viscosity sensor.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116721017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, the elastoplastic deformation behaviors of cylindrical tubes subjected to statically axial compression are studied by using finite element method (FEM). Specifically, the effects of tube geometries and strain hardening are investigated. Although it is generally recognized that the deformation in the circumferential direction is dependent on the ratio of the radius to thickness (R/t), the deformation is also greatly dependent on the edge constraint. In this study, we used flanges as an edge constraint. The deformation mode in the circumferential direction also affects the deformation in the axial direction. A method to control the deformation mode, such as adding a disk in the tube center, is proposed to maintain the deformation in the axisymmetric mode.
{"title":"Deformation Modes for Axial Crushing of Cylindrical Tubes Considering the Edge Effect","authors":"Dai-heng Chen, K. Masuda, K. Ushijima, S. Ozaki","doi":"10.1299/JCST.3.339","DOIUrl":"https://doi.org/10.1299/JCST.3.339","url":null,"abstract":"In this paper, the elastoplastic deformation behaviors of cylindrical tubes subjected to statically axial compression are studied by using finite element method (FEM). Specifically, the effects of tube geometries and strain hardening are investigated. Although it is generally recognized that the deformation in the circumferential direction is dependent on the ratio of the radius to thickness (R/t), the deformation is also greatly dependent on the edge constraint. In this study, we used flanges as an edge constraint. The deformation mode in the circumferential direction also affects the deformation in the axial direction. A method to control the deformation mode, such as adding a disk in the tube center, is proposed to maintain the deformation in the axisymmetric mode.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124163741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the rapid growth of the WAN infrastructures and enhancement of MPI libraries for WAN environment, Grid computing is expected to be a practical methodology for performing very large finite element analyses. In particular, the utilization of Grid enhanced MPI libraries allows one to execute legacy programs on WAN environments, which is very attractive for finite element application users. However, the high communication cost associated with WANs has discouraged its use as a parallel environment for finite element analysis. In this study, we focus on the utilization of Grid environments, in particular on cluster-of-clusters environments for the execution of FEA, and propose a hierarchical communication pattern to reduce the communication cost. By analytically estimating the communication cost, based on the decomposed FE mesh, we assess the effectiveness of the hierarchical communication pattern. We then show the obtained communication cost reduction by numerical experiments performed on cluster-of-clusters on WAN.
{"title":"Communication Cost Reduction by Hierarchical Communication Pattern for FE Computation on Cluster-of-Clusters","authors":"Masae Hayashi, H. Okuda","doi":"10.1299/JCST.4.136","DOIUrl":"https://doi.org/10.1299/JCST.4.136","url":null,"abstract":"With the rapid growth of the WAN infrastructures and enhancement of MPI libraries for WAN environment, Grid computing is expected to be a practical methodology for performing very large finite element analyses. In particular, the utilization of Grid enhanced MPI libraries allows one to execute legacy programs on WAN environments, which is very attractive for finite element application users. However, the high communication cost associated with WANs has discouraged its use as a parallel environment for finite element analysis. In this study, we focus on the utilization of Grid environments, in particular on cluster-of-clusters environments for the execution of FEA, and propose a hierarchical communication pattern to reduce the communication cost. By analytically estimating the communication cost, based on the decomposed FE mesh, we assess the effectiveness of the hierarchical communication pattern. We then show the obtained communication cost reduction by numerical experiments performed on cluster-of-clusters on WAN.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120895317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Evaluation of Intensity of Singularity for Three-Materials Joints with Power-Logarithmic Singularities using an Enriched Finite Element Method","authors":"Chonlada Luangarpa, H. Koguchi","doi":"10.1299/JCST.7.239","DOIUrl":"https://doi.org/10.1299/JCST.7.239","url":null,"abstract":"","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128282478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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