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作者： Garzón-Alvarado, Diego A. Narváez-Tovar, Carlos A. Silva, Octavio Engineering Modeling and Numerical Methods Group National University of Colombia Cra 30 No 45-03 Bogotá Colombia Mechanical Engineering Applications and Research Group Santo Tomás University Cra 9 No 51-11 Bogotá Colombia Engineering Modeling and Numerical Methods Group National University of Colombia Cra 30 No. 45-03 Bogotá Colombia Physical Rehabilitation Department National University of Colombia Cra 30 No 45-03 Bogotá Colombia

The growth plate is a structure formed of cells called chondrocytes;these are arranged in columns and provide the elongation of bone due to their proliferation and hypertrophy. In each column, we can see chondrocytes in their proliferating state, which are constantly dividing, and in hypertrophic state, which grow in a nearly spherical shape. These cells express different proteins and molecules throughout their half-life and exhibit a special behavior depending on their local mechanical and biochemical environments. This article develops a mathematical model that describes the relationship of geometry, growth by proliferation and hypertrophy, and vascular invasion with biochemical and mechanical factors present during endochondral ossification. © 2011 World Scientific Publishing Company.

关键词： Pathology

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A pulse-echo measurement setup to determine viscoelastic material parameters

A pulse-echo measurement setup to determine viscoelastic mat...

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2023 International Congress on Ultrasonics, ICU Beijing 2023

作者： Dreiling, Dmitrij Itner, Dominik Hetkämper, Tim Birk, Carolin Gravenkamp, Hauke Henning, Bernd Measurement Engineering Group Paderborn University Paderborn33098 Germany Institute of Structural Analysis University of Duisburg-Essen Essen45141 Germany International Centre for Numerical Methods in Engineering Barcelona08034 Spain

Due to their versatility, the application of polymers in research and industry continues to *** the majority of design processes are simulation-aided, precise material parameters are required to obtain realistic *** quasi-statically and destructively measured material parameters provided by manufacturers for this purpose are usually *** acoustic method is generally capable of measuring the frequency-dependent viscoelastic material parameters in a non-destructive *** particular, an ultrasonic transmission measurement setup for determining these parameters has already been presented in previous ***, this approach has several drawbacks, including a low sensitivity to shear *** increase the sensitivity to shear parameters, a measurement setup using a pulse-echo method with a corresponding inverse approach is presented to obtain viscoelastic material parameters of polymers.A brief comparison is made between the transmission and pulse-echo methods. © 2024 Institute of Physics Publishing. All rights reserved.

关键词： Ultrasonic transmission

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Statistical assessment of the financial performance of shale-gas wells coupling stochastic and numerical simulation

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Petroleum Science 2024年第6期21卷 4497-4511页

作者： Andres Soage Luis Ramirez Ruben Juanes Luis Cueto-Felgueroso Ignasi Colominas Group of Numerical Methods in Engineering-GMNI Center for TechnologicalInnovation in Construction and Civil Engineering-CITEEC.Civil Engineering SchoolUniversity of a CorunaCampus of ElvinaA Coruna15008GaliciaSpain Department of Civil Engineering:Hydraulics Energy and Environment.Polytechnic University of MadridMadrid2006Spain Department of Civil and Environmental Engineering Massachusetts Institute of TechnologyCambridge02139MAUA Department of Earth Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridge239MAUSA

We present a new methodology to statistically determine the net present value(NPV)and internal rate of return(IRR)as financial estimators of shale gas *** method allows us to forecast,in a fully probabilistic setting,financial performance risk and to understand the importance of the different factors that impact *** methodology developed in this study combines,through Monte Carlo simulation,the computational modeling of gas production from shale gas wells with a stochastic simulation of gas price as a geometric Brownian motion(GMB).To illustrate the methodology's validity,we apply it to an analysis of investments in shale gas *** results show that gas price volatility is a key variable in the performance of an investment of this type,in such a way that at high volatilities,the potential return on an investment in shale gas increases significantly,but so do the risks of economic *** finding is consistent with the history of shale gas operations in which huge investment successes coexist with unexpected investment failures.

关键词： Gas volatility Shale gas Net presentvalue Internal ratereturn Stochastic model Financial estimator MonteCarlosimulation Kernel densityfunction

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Improvements in the treatment of stress constraints in structural topology optimization problems

Improvements in the treatment of stress constraints in struc...

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作者： París, J. Navarrina, F. Colominas, I. Casteleiro, M. Group of Numerical Methods in Engineering Universidade da Corua Civil Eng. School Campus de Elvia s/n 15071 A Corua Spain

Topology optimization of continuum structures is a relatively new branch of the structural optimization field. Since the basic principles were first proposed by Bendsøe and Kikuchi in 1988, most of the work has been dedicated to the so-called maximum stiffness (or minimum compliance) formulations. However, since a few years different approaches have been proposed in terms of minimum weight with stress (and/or displacement) constraints. These formulations give rise to more complex mathematical programming problems, since a large number of highly non-linear (local) constraints must be taken into account. In an attempt to reduce the computational requirements, in this paper, we propose different alternatives to consider stress constraints and some ideas about the numerical implementation of these algorithms. Finally, we present some application examples. © 2009 Elsevier B.V. All rights reserved.

关键词： Constrained optimization

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On the forward simulation and cost functions for the ultrasonic material characterization of polymers

On the forward simulation and cost functions for the ultraso...

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92nd Annual Meeting of the International Association of Applied Mathematics and Mechanics, GAMM 2021

作者： Itner, Dominik Gravenkamp, Hauke Dreiling, Dmitrij Feldmann, Nadine Henning, Bernd Birk, Carolin Department of Civil Engineering University of Duisburg-Essen Essen45141 Germany International Centre for Numerical Methods in Engineering Barcelona08034 Spain Measurement Engineering Group Paderborn University Paderborn33098 Germany

In this contribution, we describe the identification of the elastic properties of polymers in use-specific setups, in particular the high-frequency behavior (compared to quasi-static or low-frequency behavior that is usually characterized). Such a parameter search can be expressed as an inverse problem by comparing experimental measurements with adequate simulated data. We employ an axisymmetric scaled boundary finite element formulation to model the propagation of ultrasonic guided waves through cylindrical polymeric samples as the so-called forward model of an optimization procedure. The simulated dynamic response is compared to a reference signal, and gradient descent-based optimization is used to find the best possible material parameter fit. We present a cost function based on the wavelet convolution that results in a locally convex cost surface well suited for gradient descent optimization. © 2021 The Authors. Proceedings in Applied Mathematics & Mechanics published by Wiley-VCH GmbH.

关键词： Cost functions

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Validating the predictions of mathematical models describing tumor growth and treatment response

arXiv

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arXiv 2025年

作者： Lorenzo, Guillermo Hormuth, David A. Wu, Chengyue Pash, Graham Chaudhuri, Anirban Lima, Ernesto A.B.F. Okereke, Lois C. Patel, Reshmi Willcox, Karen Yankeelov, Thomas E. Group of Numerical Methods in Engineering Department of Mathematics University of A Coruña Spain Oden Institute for Computational Engineering and Sciences The University of Texas at Austin AustinTX United States Livestrong Cancer Institutes The University of Texas at Austin AustinTX United States Department of Imaging Physics The University of Texas MD Anderson Cancer Center HoustonTX United States Department of Breast Imaging The University of Texas MD Anderson Cancer Center HoustonTX United States Department of Biostatistics The University of Texas MD Anderson Cancer Center HoustonTX United States Institute for Data Science in Oncology The University of Texas MD Anderson Cancer Center HoustonTX United States Texas Advanced Computing Center The University of Texas at Austin AustinTX United States Department of Biomedical Engineering The University of Texas at Austin AustinTX United States Department of Diagnostic Medicine The University of Texas at Austin AustinTX United States Department of Oncology The University of Texas at Austin AustinTX United States

Despite advances in methods to interrogate tumor biology, the observational and population-based approach of classical cancer research and clinical oncology does not enable anticipation of tumor outcomes to hasten the discovery of cancer mechanisms and personalize disease management. To address these limitations, individualized cancer forecasts have been shown to predict tumor growth and therapeutic response, inform treatment optimization, and guide experimental efforts. These predictions are obtained via computer simulations of mathematical models that are constrained with data from a patient’s cancer and experiments. This book chapter addresses the validation of these mathematical models to forecast tumor growth and treatment response. We start with an overview of mathematical modeling frameworks, model selection techniques, and fundamental metrics. We then describe the usual strategies employed to validate cancer forecasts in preclinical and clinical scenarios. Finally, we discuss existing barriers in validating these predictions along with potential strategies to address them. © 2025, CC BY-NC-ND.

关键词： Prediction models

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A higher-order finite volume method using multiresolution reproducing kernels

A higher-order finite volume method using multiresolution re...

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4th International Workshop on Meshfree methods for Partial Differential Equations

作者： Nogueira, Xesús Cueto-Felgueroso, Luis Colominas, Ignasi Navarrina, Fermín Casteleiro, Manuel Group of Numerical Methods in Engineering GMNI Dept. of Applied Mathematics Civil Engineering School University of A Coruña Campus de Elviña 15071 A Coruña Spain Department of Aeronautics and Astronautics Massachusetts Institute of Technology 77 Massachusetts Ave 37-451 Cambridge MA 02139 United States

ISBN: (纸本)9783540799931

In this contribution we describe a numerical method based on the application of a meshfree interpolation technique (Moving Least Squares (MLS)), for the development of a higher-order finite volume discretization useful on structured and unstructured grids. With this procedure it is possible to build a higher-order scheme in which the computation of the derivatives is performed in a truly threedimensional way. We use a MLS approach to compute the successive derivatives needed for the approximation of variables at element interfaces using Taylor series. Due to the use of cubic (or higher) reconstructions with the MLS technique, viscous fluxes are also approximated with higher-order accuracy and can be directly computed at edges. The higher-order accuracy achieved by this method makes it suitable for aeroacoustics problems and DNS and LES of turbulent flows. One of the advantages of the use of the meshfree method on a finite volume framework is that it is possible to exploit all the shock capturing techniques developed for finite volume methods, allowing the computation of compressible flows. Moreover, we also present the application of this interpolation technique to shock detection. We make use of its connection with wavelets, and develop a technique we believe superior to traditional shock capturing methods. This application could be included in a very natural way in the computations with the method presented herein.

关键词： Compressible flow

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A holistic seismic risk scheme using fuzzy sets part one: The social system fragility 4

A holistic seismic risk scheme using fuzzy sets part one: Th...

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4th International Conference on Simulation and Modeling Methodologies, Technologies and Applications, SIMULTECH 2014

作者： González, J. Rubén Nebot, Àngela Mugica, Francisco Carreño, Martha-Liliana Barbat, Alex H. IUSS UME School Via Ferrata 45 Pavia Italy Soft Computing Group Technical University of Catalonia Jordi Girona Salgado 1-3 Barcelona Spain International Center for Numerical Methods in Engineering Technical University of Catalonia Jordi Girona Salgado 1-3 Barcelona Spain

ISBN: (纸本)9789897580383

Hazard related Risk is a strange concept since its represents something that has not happened yet, something which is blur and randomness related. Along its estimation, social vulnerability aspects come to arise. Such aspects are even more difficult to define in part because there is still missing a robust way to quantify them and, therefore, to establish a clear analytic framework useful to understand inherent complexities of a human society. In this paper, we build a social aggravation coefficient fuzzy model considering Cardona-Carreño aggravation descriptors. By reducing the number of aggravation descriptors and establishing fuzzy logic rules between them, we found similar results in tendency and spatial distribution for seismic resilience and fragility at Barcelona, Spain. We used a classical Mamdani fuzzy approach, supported by well established fuzzy theory, which is characterized by a high expressive power and an intuitive human-like manner. We believe that in this way, a more clear analyses of the resilience and fragility bond can be done exploiting in a more suitable way fuzzy logic capabilities, because the inference process to obtain an aggravation coefficient is based precisely on the establishment of rules (if-then type) directly over the involved variables in social vulnerability formation which allows a smooth application of risk management knowledge, encouraging debate over the used rules, besides the discussion among the employed membership functions. © 2014 SciTePress. All rights reserved.

关键词： Risk management

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A novel linear technique to estimate the epipolar geometry

A novel linear technique to estimate the epipolar geometry

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： E. Izquierdo V. Guerra Department of Electronic Engineering Queen Mary University of London London UK Cybernetics and Physics Group of Numerical Methods Institute of Mathematics Havana Cuba

The accurate reconstruction of the 3D scene structure from two different projections and the estimation of the camera scene geometry is of paramount importance in many computer vision tasks. Most of the information about the camera-scene geometry is encapsulated in the fundamental matrix. Estimating the fundamental matrix has been an object of research for many years and continues to be a challenging task in current computer vision systems. While nonlinear iterative approaches have been successful in dealing with the high instability of the underlying problem, their inherent large workload makes these approaches inappropriate for real-time applications. Practical aspects of highly efficient linear methods are studied and a novel low-cost and accurate linear algorithm is introduced. The performance of the proposed approach is assessed by several experiments on real images.

关键词： Layout Cameras Computer vision Computational geometry Application software Robot vision systems Data mining Calibration Image reconstruction Information geometry

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A holistic seismic risk scheme using fuzzy sets part one: The social system fragility

A holistic seismic risk scheme using fuzzy sets part one: Th...

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International Conference on Simulation and Modeling Methodologies, Technologies and Applications (SIMULTECH)

作者： J. Rubén González Àngela Nebot Francisco Mugica Martha-Liliana Carreño Alex H. Barbat IUSS UME School Pavia Italy Soft Computing Group Technical University of Catalonia Barcelona Spain International Center for Numerical Methods in Engineering Technical University of Catalonia Barcelona Spain

关键词： Resilience Indexes Biological system modeling Mathematical model Fuzzy sets Fuzzy logic Pragmatics

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