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Analysis of the Static Behavior of a Single Tree on a Finite Element Model.

ABSTRACT: This work deals with the innovated complex process of tree risk assessment, from precise geometrical tree shape acquisition to building and analyzing a finite element model under specified load. The acquisition of the 3D geometry of the tree was performed by means of terrestrial laser scanning. Obtained point cloud was optimized and additionally converted to a 3D CAD model, representing the bearing skeleton compound of trunk and main branches. For structural analysis purposes, a finite element model (FEM) was built in the form of beam structure fixed to the ground. Particular beams were defined by geometry, material properties of wood, and cross sections. An acoustic tomography was applied for determination of the precise cross section on investigated locations of an analysis model. Finite element analysis performed on the computational model shows the bearing capacity and deformations of the whole tree structure caused by combinations of load cases like self-weight and static equivalent of wind load. The results of the structural analysis called attention to potentially dangerous places within the tree structure with extreme node displacements or tensile stresses on beams. Thus, we observed a maximal horizontal displacement of 280.4 mm in node N34 and dangerous tensile stress in node N26, where it reaches +23.6 MPa. After filtering some beams with an abnormal cross section geometry, the finite element analysis of the whole tree structure showed the highest tensile stress of +8.8 MPa and highest compressive stress of -8.9 MPa. The suggested method can be applied generally for the prediction of potentially risky tree suspected of breakage and especially for monumental trees, where the presented method can be mostly applicable.

SUBMITTER: Moravcik L

PROVIDER: S-EPMC8309158 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Alar rim retraction is the most common unintended consequence of tissue remodeling that results from overresection of the cephalic lateral crural cartilage; however, the complex tissue remodeling process that produces this shape change is not well understood.To simulate how resection of cephalic trim alters the stress distribution within the human nose in response to tip depression (palpation) and to simulate the internal forces generated after cephalic trim that may lead to alar rim retraction cephalically and upward rotation of the nasal tip.A multicomponent finite element model was derived from maxillofacial computed tomography with 1-mm axial resolution. The 3-dimensional editing function in the medical imaging software was used to trim the cephalic portion of the lower lateral cartilage to emulate that performed in typical rhinoplasty. Three models were created: a control, a conservative trim, and an aggressive trim. Each simulated model was imported to a software program that performs mechanical simulations, and material properties were assigned. First, nasal tip depression (palpation) was simulated, and the resulting stress distribution was calculated for each model. Second, long-term tissue migration was simulated on conservative and aggressive trim models by placing normal and shear force vectors along the caudal and cephalic borders of the tissue defect.The von Mises stress distribution created by a 5-mm tip depression revealed consistent findings among all 3 simulations, with regions of high stress being concentrated to the medial portion of the intermediate crus and the caudal septum. Nasal tip reaction force marginally decreased as more lower lateral cartilage tissue was resected. Conservative and aggressive cephalic trim models produced some degree of alar rim retraction and tip rotation, which increased with the magnitude of the force applied to the region of the tissue defect.Cephalic trim was performed on a computerized composite model of the human nose to simulate conservative and aggressive trims. Internal forces were applied to each model to emulate the tissue migration that results from decades of wound healing. Our simulations reveal that the degree of tip rotation and alar rim retraction is dependent on the amount of cartilage that was resected owing to cephalic trim. Tip reaction force is marginally reduced with increasing tissue volume resection.NA.

Project description:BACKGROUND: Biological mass transport processes determine the behavior and function of cells, regulate interactions between synthetic agents and recipient targets, and are key elements in the design and use of biosensors. Accurately predicting the outcomes of such processes is crucial to both enhancing our understanding of how these systems function, enabling the design of effective strategies to control their function, and verifying that engineered solutions perform according to plan. METHODS: A Galerkin-based finite element model was developed and implemented to solve a system of two coupled partial differential equations governing biomolecule transport and reaction in live cells. The simulator was coupled, in the framework of an inverse modeling strategy, with an optimization algorithm and an experimental time series, obtained by the Fluorescence Recovery after Photobleaching (FRAP) technique, to estimate biomolecule mass transport and reaction rate parameters. In the inverse algorithm, an adaptive method was implemented to calculate sensitivity matrix. A multi-criteria termination rule was developed to stop the inverse code at the solution. The applicability of the model was illustrated by simulating the mobility and binding of GFP-tagged glucocorticoid receptor in the nucleoplasm of mouse adenocarcinoma. RESULTS: The numerical simulator shows excellent agreement with the analytic solutions and experimental FRAP data. Detailed residual analysis indicates that residuals have zero mean and constant variance and are normally distributed and uncorrelated. Therefore, the necessary and sufficient criteria for least square parameter optimization, which was used in this study, were met. CONCLUSION: The developed strategy is an efficient approach to extract as much physiochemical information from the FRAP protocol as possible. Well-posedness analysis of the inverse problem, however, indicates that the FRAP protocol provides insufficient information for unique simultaneous estimation of diffusion coefficient and binding rate parameters. Care should be exercised in drawing inferences, from FRAP data, regarding concentrations of free and bound proteins, average binding and diffusion times, and protein mobility unless they are confirmed by long-range Markov Chain-Monte Carlo (MCMC) methods and experimental observations.

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Analysis of the Static Behavior of a Single Tree on a Finite Element Model.

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