Pub Date : 2025-01-27DOI: 10.1016/j.apm.2025.115966
Emiliano Cristiani , Mario Grassi , Francesca L. Ignoto , Giuseppe Pontrelli
In this work, we deal with a mathematical model describing the dissolution process of irregularly shaped particles. In particular, we consider a complete dissolution model accounting for surface kinetics, convective diffusion, and relative velocity between fluid and dissolving particles, for three drugs with different solubility and wettability: theophylline, griseofulvin, and nimesulide. The possible subsequent recrystallization process in the bulk fluid is also considered. The governing differential equations are revisited in the context of the level-set method and Hamilton-Jacobi equations, then they are solved numerically. This choice allows us to deal with the simultaneous dissolution of hundreds of different polydisperse particles. We show the results of many computer simulations which investigate the impact of the particle size, shape, area/volume ratio, and the dependence of the interfacial mass transport coefficient on the surface curvature.
{"title":"Dissolution of variable-in-shape drug particles via the level-set method","authors":"Emiliano Cristiani , Mario Grassi , Francesca L. Ignoto , Giuseppe Pontrelli","doi":"10.1016/j.apm.2025.115966","DOIUrl":"10.1016/j.apm.2025.115966","url":null,"abstract":"<div><div>In this work, we deal with a mathematical model describing the dissolution process of irregularly shaped particles. In particular, we consider a complete dissolution model accounting for surface kinetics, convective diffusion, and relative velocity between fluid and dissolving particles, for three drugs with different solubility and wettability: theophylline, griseofulvin, and nimesulide. The possible subsequent recrystallization process in the bulk fluid is also considered. The governing differential equations are revisited in the context of the level-set method and Hamilton-Jacobi equations, then they are solved numerically. This choice allows us to deal with the simultaneous dissolution of hundreds of different polydisperse particles. We show the results of many computer simulations which investigate the impact of the particle size, shape, area/volume ratio, and the dependence of the interfacial mass transport coefficient on the surface curvature.</div></div>","PeriodicalId":50980,"journal":{"name":"Applied Mathematical Modelling","volume":"142 ","pages":"Article 115966"},"PeriodicalIF":4.4,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143071474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-27DOI: 10.1016/j.apm.2025.115973
Meng Zhang , Shuo Liu , Mingcai Xing , Lining Gao , Yi Cui
Due to high loads, low relative speeds, and poor lubrication conditions, the contact between the piston pin and pin hole is prone to reliability issues. Optimizing the pin hole profile during the design phase is crucial for enhancing stress distribution and lubrication. However, three-dimensional models are computationally intensive, posing challenges for rapid computation and shortened product development cycles. To overcome these challenges, this study establishes a two-dimensional variable thickness finite element contact model and provides a general numerical solution. Parametric modeling of the pin hole's curved profile is implemented, and an optimization method using maximum stress as the criterion is proposed. As an illustration, the stress distribution of a pin hole with a tapered profile from a typical marine engine is analyzed. The results show that the two-dimensional model closely approximates the three-dimensional finite element analysis results while increasing computational efficiency by 360 times. Furthermore, compared to the tapered profile, the optimized curved profile reduces the maximum von Mises stress in the contact area by 32.5 %.
{"title":"Rapid optimization of piston pin hole profile using variable thickness finite element method","authors":"Meng Zhang , Shuo Liu , Mingcai Xing , Lining Gao , Yi Cui","doi":"10.1016/j.apm.2025.115973","DOIUrl":"10.1016/j.apm.2025.115973","url":null,"abstract":"<div><div>Due to high loads, low relative speeds, and poor lubrication conditions, the contact between the piston pin and pin hole is prone to reliability issues. Optimizing the pin hole profile during the design phase is crucial for enhancing stress distribution and lubrication. However, three-dimensional models are computationally intensive, posing challenges for rapid computation and shortened product development cycles. To overcome these challenges, this study establishes a two-dimensional variable thickness finite element contact model and provides a general numerical solution. Parametric modeling of the pin hole's curved profile is implemented, and an optimization method using maximum stress as the criterion is proposed. As an illustration, the stress distribution of a pin hole with a tapered profile from a typical marine engine is analyzed. The results show that the two-dimensional model closely approximates the three-dimensional finite element analysis results while increasing computational efficiency by 360 times. Furthermore, compared to the tapered profile, the optimized curved profile reduces the maximum von Mises stress in the contact area by 32.5 %.</div></div>","PeriodicalId":50980,"journal":{"name":"Applied Mathematical Modelling","volume":"142 ","pages":"Article 115973"},"PeriodicalIF":4.4,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143295943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-27DOI: 10.1016/j.apm.2025.115982
Diego Hayashi Alonso , Julio Romano Meneghini , Emílio Carlos Nelli Silva
Screw-type pumping is one of the earliest types of pumping that have been explored. It has been later developed for various types of applications, including water, oil, cement, energy generation/recovery, labyrinth seals etc. Due to the screw shape, the flow is intrinsically three-dimensional, which makes it computationally expensive for the simulation. Adding to that, since the efficiency of the screw-type pumping is usually low, it may be necessary to consider optimization. When taking into consideration an optimization method with a high flexibility in the design (topology optimization), the computational cost becomes much more prohibitive, since there are usually various optimization iterations, there is a simulation for each optimization iteration, and the adjoint model has to be computed in each iteration as well. Therefore, this work formulates a simplified model for the topology optimization of screw-type devices, using a Multiple Reference Frame-based approach. This simplified model operates in a two-dimensional mesh, and makes some assumptions and approximations inside the screw zone, resulting in a similar tendency to the 3D configuration, which should be enough in terms of a design procedure, at least on a preliminary level. Two types of objective functions are considered: one that considers a pump-type operation, in which the flow performance needs to be improved, and one that considers a labyrinth seal-type operation, in which the leakage flow should be minimized. The design variable is pointwise linear, and optimized through an optimization algorithm based on integer programming. The fluid flow is taken as laminar or turbulent. Some of the numerical examples are presented for the topology optimization using the proposed model.
{"title":"Topology optimization method for screw-type pumping using a Multiple Reference Frame-based approach","authors":"Diego Hayashi Alonso , Julio Romano Meneghini , Emílio Carlos Nelli Silva","doi":"10.1016/j.apm.2025.115982","DOIUrl":"10.1016/j.apm.2025.115982","url":null,"abstract":"<div><div>Screw-type pumping is one of the earliest types of pumping that have been explored. It has been later developed for various types of applications, including water, oil, cement, energy generation/recovery, labyrinth seals etc. Due to the screw shape, the flow is intrinsically three-dimensional, which makes it computationally expensive for the simulation. Adding to that, since the efficiency of the screw-type pumping is usually low, it may be necessary to consider optimization. When taking into consideration an optimization method with a high flexibility in the design (topology optimization), the computational cost becomes much more prohibitive, since there are usually various optimization iterations, there is a simulation for each optimization iteration, and the adjoint model has to be computed in each iteration as well. Therefore, this work formulates a simplified model for the topology optimization of screw-type devices, using a Multiple Reference Frame-based approach. This simplified model operates in a two-dimensional mesh, and makes some assumptions and approximations inside the screw zone, resulting in a similar tendency to the 3D configuration, which should be enough in terms of a design procedure, at least on a preliminary level. Two types of objective functions are considered: one that considers a <em>pump-type</em> operation, in which the flow performance needs to be improved, and one that considers a <em>labyrinth seal-type</em> operation, in which the leakage flow should be minimized. The design variable is pointwise linear, and optimized through an optimization algorithm based on integer programming. The fluid flow is taken as laminar or turbulent. Some of the numerical examples are presented for the topology optimization using the proposed model.</div></div>","PeriodicalId":50980,"journal":{"name":"Applied Mathematical Modelling","volume":"142 ","pages":"Article 115982"},"PeriodicalIF":4.4,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143071471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-27DOI: 10.1016/j.apm.2025.115979
Jianqiang Yang , Fu Yan , Jin Zhang , Changgen Peng
The grey wolf optimizer is a renowned algorithm within the realm of swarm intelligence. However, it is hindered by a few drawbacks such as slow convergence rate, limited population diversity, and a propensity to fall into local optima in certain scenarios. In this study, we introduce a groundbreaking hybrid algorithm called Hybrid chaos game and grey wolf optimization, which ingeniously fuses the grey wolf optimizer with the Chaos Game Optimizer. This novel amalgamation significantly bolsters both the exploratory and exploitative facets of the grey wolf optimizer, enriching its diversity and enhancing its convergence precision, while preserving robust exploratory capabilities. In order to fully demonstrate the superior performance of the algorithm, the paper is divided into two parts. In the first part, the proposed algorithm is analyzed through rigorous experiments on different classes of test functions of the Congress on Evolutionary Computation benchmark 2014 using Friedman statistical test, among them, comparing the original grey wolf optimizer algorithm, it achieved better results among 28 functions. In the second part, the proposed algorithm is used to solve unmanned aerial vehicle path planning problems. These real-world problems are used as test problems to evaluate the solving ability of the proposed algorithm.The results show that the proposed algorithm still has a good performance in 6 scenarios of different complexity in the setup. The main goal of hybrid Chaotic Game Optimization and Grey Wolf Optimization is to provide an alternative perspective for dealing with complex optimization problems.
{"title":"Hybrid chaos game and grey wolf optimization algorithms for UAV path planning","authors":"Jianqiang Yang , Fu Yan , Jin Zhang , Changgen Peng","doi":"10.1016/j.apm.2025.115979","DOIUrl":"10.1016/j.apm.2025.115979","url":null,"abstract":"<div><div>The grey wolf optimizer is a renowned algorithm within the realm of swarm intelligence. However, it is hindered by a few drawbacks such as slow convergence rate, limited population diversity, and a propensity to fall into local optima in certain scenarios. In this study, we introduce a groundbreaking hybrid algorithm called Hybrid chaos game and grey wolf optimization, which ingeniously fuses the grey wolf optimizer with the Chaos Game Optimizer. This novel amalgamation significantly bolsters both the exploratory and exploitative facets of the grey wolf optimizer, enriching its diversity and enhancing its convergence precision, while preserving robust exploratory capabilities. In order to fully demonstrate the superior performance of the algorithm, the paper is divided into two parts. In the first part, the proposed algorithm is analyzed through rigorous experiments on different classes of test functions of the Congress on Evolutionary Computation benchmark 2014 using Friedman statistical test, among them, comparing the original grey wolf optimizer algorithm, it achieved better results among 28 functions. In the second part, the proposed algorithm is used to solve unmanned aerial vehicle path planning problems. These real-world problems are used as test problems to evaluate the solving ability of the proposed algorithm.The results show that the proposed algorithm still has a good performance in 6 scenarios of different complexity in the setup. The main goal of hybrid Chaotic Game Optimization and Grey Wolf Optimization is to provide an alternative perspective for dealing with complex optimization problems.</div></div>","PeriodicalId":50980,"journal":{"name":"Applied Mathematical Modelling","volume":"142 ","pages":"Article 115979"},"PeriodicalIF":4.4,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143071472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-27DOI: 10.1016/j.apm.2025.115980
Xudong Cheng , Yanxiang Guo , Xingji Zhu , Wenxuan Li , Wenjun Hu , Longjun Xu , Lili Xie
Tunnel Boring Machine (TBM) tunneling generates construction loads accompanied by unloading effect, forming additional stress field. In the previous analytical study based on classic Mindlin theory, only the additional normal stress is considered, and the additional shear stress is generally ignored. In particular, the additional stress caused by the construction loads and unloading effect of the double shield TBM (DS-TBM) is still not clear. In this paper, the application range of Mindlin theory was extended from concentrated load in vertical or horizontal direction to load in any form and direction by integration transformation and coordinate transformation. Then, combined with the accurate description of construction loads and unloading effect, an analytical solution method was proposed to obtain the additional stress field including shear and normal stress caused by the DS-TBM tunneling. The results show that the principal additional shear stress has a significant contribution to the additional stress field; the influence of unloading force on the additional stress field has cumulative effects. This work can provide a reliable and rapid evaluation method for the safe application of DS-TBM tunneling.
{"title":"Analytical study on additional stress field of double shield TBM tunneling based on Mindlin theory","authors":"Xudong Cheng , Yanxiang Guo , Xingji Zhu , Wenxuan Li , Wenjun Hu , Longjun Xu , Lili Xie","doi":"10.1016/j.apm.2025.115980","DOIUrl":"10.1016/j.apm.2025.115980","url":null,"abstract":"<div><div>Tunnel Boring Machine (TBM) tunneling generates construction loads accompanied by unloading effect, forming additional stress field. In the previous analytical study based on classic Mindlin theory, only the additional normal stress is considered, and the additional shear stress is generally ignored. In particular, the additional stress caused by the construction loads and unloading effect of the double shield TBM (DS-TBM) is still not clear. In this paper, the application range of Mindlin theory was extended from concentrated load in vertical or horizontal direction to load in any form and direction by integration transformation and coordinate transformation. Then, combined with the accurate description of construction loads and unloading effect, an analytical solution method was proposed to obtain the additional stress field including shear and normal stress caused by the DS-TBM tunneling. The results show that the principal additional shear stress has a significant contribution to the additional stress field; the influence of unloading force on the additional stress field has cumulative effects. This work can provide a reliable and rapid evaluation method for the safe application of DS-TBM tunneling.</div></div>","PeriodicalId":50980,"journal":{"name":"Applied Mathematical Modelling","volume":"142 ","pages":"Article 115980"},"PeriodicalIF":4.4,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143175297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-27DOI: 10.1016/j.apm.2025.115976
Wei Gao, Shou Yuan, Shuangshuang Ge, Zhihao Zhao, Yi Han
To study the fracture of a water-bearing rock, according to the characteristics of contact between the water and a rock crack, the influential mechanism of water on the rock crack is analyzed according to two different zones (crack zone and matrix zone) of the rock. Based on the influential mechanism of water on rock cracks and by using the complex function method, the expression of the stress intensity factor at the crack tip of the water-bearing rock has been derived. Moreover, taking the symmetric arrangement of three collinear cracks under compression as an example, the effect of main influence factors (water pressure on the crack surface, cohesion and internal friction angle of the rock, and the friction coefficient between the crack surfaces) on the stress intensity factor has been analyzed, and their corresponding coefficients of the influence have been obtained. At last, by using the contour integral method in the finite element method, the rationality of the theoretical results has been verified. From the study, for the water effect, there is a crack damage, which will cause an increase in crack length, and the friction coefficient between the crack surfaces will decrease by the water immersion lubrication on the crack surfaces. Moreover, there is water pressure on the crack surfaces which is similar to the wedging effect of water pressure on the crack tip and the deterioration of rock mechanical parameters. Therefore, the stress intensity factor at the crack tip will be enlarged by the water effect.
{"title":"Theoretical study on the stress intensity factor at the crack tip of a water-bearing rock","authors":"Wei Gao, Shou Yuan, Shuangshuang Ge, Zhihao Zhao, Yi Han","doi":"10.1016/j.apm.2025.115976","DOIUrl":"10.1016/j.apm.2025.115976","url":null,"abstract":"<div><div>To study the fracture of a water-bearing rock, according to the characteristics of contact between the water and a rock crack, the influential mechanism of water on the rock crack is analyzed according to two different zones (crack zone and matrix zone) of the rock. Based on the influential mechanism of water on rock cracks and by using the complex function method, the expression of the stress intensity factor at the crack tip of the water-bearing rock has been derived. Moreover, taking the symmetric arrangement of three collinear cracks under compression as an example, the effect of main influence factors (water pressure on the crack surface, cohesion and internal friction angle of the rock, and the friction coefficient between the crack surfaces) on the stress intensity factor has been analyzed, and their corresponding coefficients of the influence have been obtained. At last, by using the contour integral method in the finite element method, the rationality of the theoretical results has been verified. From the study, for the water effect, there is a crack damage, which will cause an increase in crack length, and the friction coefficient between the crack surfaces will decrease by the water immersion lubrication on the crack surfaces. Moreover, there is water pressure on the crack surfaces which is similar to the wedging effect of water pressure on the crack tip and the deterioration of rock mechanical parameters. Therefore, the stress intensity factor at the crack tip will be enlarged by the water effect.</div></div>","PeriodicalId":50980,"journal":{"name":"Applied Mathematical Modelling","volume":"142 ","pages":"Article 115976"},"PeriodicalIF":4.4,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143174926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-27DOI: 10.1016/j.apm.2025.115969
Tong Wang , Dapeng Tan , Yueqiao Hou , Chengyan Wang , Jinwei Cheng , Wenlong Song
Adverse conditions induce surface cracks in fluid-filled thin cylindrical shells, thereby diminishing their mechanical properties and load-bearing capacity. However, due to the discontinuity in vibration characteristics near the cracks and the strong coupling during the transport process, the free vibration response solution and state recognition oriented to the fluid-filled thin cylindrical shell containing a surface crack still face significant challenges. To address the above issues, a free vibration response solution method for fluid-filled thin cylindrical shell containing a surface crack based on Linear Spring Model and linear potential flow theory is proposed, which elucidates the interaction mechanism within the fluid-shell-crack coupling state and establishes a quantitative relationship between these coupling parameters and vibration response characteristics. Subsequently, a natural frequency isoline-based state recognition method is introduced to achieve unified identification of crack morphology and fluid state. Finally, a multi-channel LMS vibration test platform is built, and the error between analytical and experimental results is less than 4 %, thereby corroborating the accuracy and validity of the proposed vibration response solution method. The research findings indicate that both surface cracks and internal fluid contribute to the reduction in natural frequency, with the crack angle being the primary factor. Additionally, it is observed that apart from internal fluid velocity, all parameters exhibit extreme values near a length ratio of L/R = 10.
{"title":"Analytical and experimental investigation of vibration response for the cracked fluid-filled thin cylindrical shell under transport condition","authors":"Tong Wang , Dapeng Tan , Yueqiao Hou , Chengyan Wang , Jinwei Cheng , Wenlong Song","doi":"10.1016/j.apm.2025.115969","DOIUrl":"10.1016/j.apm.2025.115969","url":null,"abstract":"<div><div>Adverse conditions induce surface cracks in fluid-filled thin cylindrical shells, thereby diminishing their mechanical properties and load-bearing capacity. However, due to the discontinuity in vibration characteristics near the cracks and the strong coupling during the transport process, the free vibration response solution and state recognition oriented to the fluid-filled thin cylindrical shell containing a surface crack still face significant challenges. To address the above issues, a free vibration response solution method for fluid-filled thin cylindrical shell containing a surface crack based on Linear Spring Model and linear potential flow theory is proposed, which elucidates the interaction mechanism within the fluid-shell-crack coupling state and establishes a quantitative relationship between these coupling parameters and vibration response characteristics. Subsequently, a natural frequency isoline-based state recognition method is introduced to achieve unified identification of crack morphology and fluid state. Finally, a multi-channel LMS vibration test platform is built, and the error between analytical and experimental results is less than 4 %, thereby corroborating the accuracy and validity of the proposed vibration response solution method. The research findings indicate that both surface cracks and internal fluid contribute to the reduction in natural frequency, with the crack angle being the primary factor. Additionally, it is observed that apart from internal fluid velocity, all parameters exhibit extreme values near a length ratio of L<em>/R</em> = 10.</div></div>","PeriodicalId":50980,"journal":{"name":"Applied Mathematical Modelling","volume":"142 ","pages":"Article 115969"},"PeriodicalIF":4.4,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143353519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-25DOI: 10.1016/j.apm.2025.115981
Partha Sengupta , Subrata Chakraborty
A Bayesian model updating approach is proposed where an active Kriging-based metamodel efficiently approximates the expensive-to-evaluate posterior probability density. Unlike the usual Kriging-based model updating approach, the present study competently approximates the modal responses of different natures and dimensions. In detail, an active learning function is proposed where the computationally intensive expectation function evaluation in the usual least improvement function is modified with an expected improvement technique. For computational efficiency in constructing the Kriging model, the unknown modal coordinates are obtained using an improved model reduction technique to evade complete model evaluations. The proposed Kriging model approximates the posterior probability density of model parameters so that each term of the learning function is updatable. This is likely to improve the accuracy of the learning function. Finally, a sampling strategy using affine invariance within the Transitional Markov Chain Monte Carlo technique estimates a multi-dimensional scaling factor that accounts for the mode shapes and frequencies of different natures and dimensions. The proposed algorithm is illustrated numerically by considering a realistic ten-storey building and a multi-span curved bridge. The estimated model parameters by the proposed approach at various noise levels indicate its accuracy and efficiency compared to existing approaches.
{"title":"Bayesian model updating in an active Kriging-based metamodeling framework","authors":"Partha Sengupta , Subrata Chakraborty","doi":"10.1016/j.apm.2025.115981","DOIUrl":"10.1016/j.apm.2025.115981","url":null,"abstract":"<div><div>A Bayesian model updating approach is proposed where an active Kriging-based metamodel efficiently approximates the expensive-to-evaluate posterior probability density. Unlike the usual Kriging-based model updating approach, the present study competently approximates the modal responses of different natures and dimensions. In detail, an active learning function is proposed where the computationally intensive expectation function evaluation in the usual least improvement function is modified with an expected improvement technique. For computational efficiency in constructing the Kriging model, the unknown modal coordinates are obtained using an improved model reduction technique to evade complete model evaluations. The proposed Kriging model approximates the posterior probability density of model parameters so that each term of the learning function is updatable. This is likely to improve the accuracy of the learning function. Finally, a sampling strategy using affine invariance within the Transitional Markov Chain Monte Carlo technique estimates a multi-dimensional scaling factor that accounts for the mode shapes and frequencies of different natures and dimensions. The proposed algorithm is illustrated numerically by considering a realistic ten-storey building and a multi-span curved bridge. The estimated model parameters by the proposed approach at various noise levels indicate its accuracy and efficiency compared to existing approaches.</div></div>","PeriodicalId":50980,"journal":{"name":"Applied Mathematical Modelling","volume":"142 ","pages":"Article 115981"},"PeriodicalIF":4.4,"publicationDate":"2025-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143174951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The multi-material topology optimization design is a significant area of research, especially when considering geometric nonlinearity. Traditional topology optimization methods are primarily developed based on linear problems and often face the issue where the number of design variables increases proportionally with the number of candidate materials. Additionally, the interphases obtained using stair-step interpolation formulations are often enclosed within adjacent materials, leading to impractical designs and suboptimal results. To address these challenges, a univariate combination interpolation-based multi-material topology optimization method is proposed and applied to multi-material topology optimization considering geometric nonlinearity. Firstly, the univariate characteristic function is utilized to map the single design variable field into multiple topology density fields, each represented by a distinct topology density function. These topology density fields are then processed using a smoothing algorithm based on the convolution-based density filtering method. Subsequently, a physical density field is established through a regularized Heaviside function. By integrating the univariate characteristic function with the convolution density filtering technique, a series of topology density functions with adequate smoothness and continuity is embedded within the Discrete Material Optimization (DMO) interpolation formulation, forming the composite interpolation model. Due to the non-convexity of the topology optimization problem, a continuation strategy for penalty parameter and smoothness parameter adaptive adjustment is introduced to enhance the robustness and optimization efficiency of the algorithm. The Method of Moving Asymptotes (MMA) gradient optimization algorithm is employed to update the design variables iteratively. Finally, a series of two-dimensional and three-dimensional numerical examples considering geometric nonlinearity is presented, with the objective of minimizing compliance under volume constraints. The results indicate that the proposed method effectively combines the advantages of the DMO method with the univariate characteristic function in multi-material topology optimization considering geometric nonlinearity, which successfully addresses the challenges posed by interphase materials between stiff and compliant materials. Moreover, the number of design variables is independent of the number of candidate materials, demonstrating the successful extension of the proposed method to problems involving geometric nonlinearity.
{"title":"A geometric nonlinear multi-material topology optimization method based on univariate combination interpolation scheme","authors":"Haitao Liao, Wenhao Yuan, Mengdi Qin, Yixing Huang","doi":"10.1016/j.apm.2025.115970","DOIUrl":"10.1016/j.apm.2025.115970","url":null,"abstract":"<div><div>The multi-material topology optimization design is a significant area of research, especially when considering geometric nonlinearity. Traditional topology optimization methods are primarily developed based on linear problems and often face the issue where the number of design variables increases proportionally with the number of candidate materials. Additionally, the interphases obtained using stair-step interpolation formulations are often enclosed within adjacent materials, leading to impractical designs and suboptimal results. To address these challenges, a univariate combination interpolation-based multi-material topology optimization method is proposed and applied to multi-material topology optimization considering geometric nonlinearity. Firstly, the univariate characteristic function is utilized to map the single design variable field into multiple topology density fields, each represented by a distinct topology density function. These topology density fields are then processed using a smoothing algorithm based on the convolution-based density filtering method. Subsequently, a physical density field is established through a regularized Heaviside function. By integrating the univariate characteristic function with the convolution density filtering technique, a series of topology density functions with adequate smoothness and continuity is embedded within the Discrete Material Optimization (DMO) interpolation formulation, forming the composite interpolation model. Due to the non-convexity of the topology optimization problem, a continuation strategy for penalty parameter and smoothness parameter adaptive adjustment is introduced to enhance the robustness and optimization efficiency of the algorithm. The Method of Moving Asymptotes (MMA) gradient optimization algorithm is employed to update the design variables iteratively. Finally, a series of two-dimensional and three-dimensional numerical examples considering geometric nonlinearity is presented, with the objective of minimizing compliance under volume constraints. The results indicate that the proposed method effectively combines the advantages of the DMO method with the univariate characteristic function in multi-material topology optimization considering geometric nonlinearity, which successfully addresses the challenges posed by interphase materials between stiff and compliant materials. Moreover, the number of design variables is independent of the number of candidate materials, demonstrating the successful extension of the proposed method to problems involving geometric nonlinearity.</div></div>","PeriodicalId":50980,"journal":{"name":"Applied Mathematical Modelling","volume":"142 ","pages":"Article 115970"},"PeriodicalIF":4.4,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143071522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-23DOI: 10.1016/j.apm.2025.115972
Suliman Jamiel M. Abdalla , Keshlan S. Govinder , Faraimunashe Chirove
The 2018–2020 Ebola virus disease (EVD) outbreak in the Democratic Republic of Congo (DR Congo) was the second-largest in history, mainly because of security challenges and community mistrust. This study evaluates the impact of geographically targeted vaccinations (GTVs) as a complementary strategy when traditional measures—contact tracing, ring vaccinations, and antiviral treatments—are insufficient. We develop a novel mathematical model, incorporating key factors such as transmission from the deceased, heterogeneity in susceptibility, migration patterns, and control measures. Numerical simulations reveal that while traditional control measures substantially reduce cumulative cases to 3500 within one year, compared to over 10 million cases without intervention, population movement into high-infection areas intensifies transmission by increasing the pool of susceptible individuals. This highlights the need to reduce the flow of population into high-risk regions. Sensitivity analysis identifies key parameters, including effective contact rate and the rate of movement into areas with high infections, as critical epidemic drivers. Contour plots demonstrate that GTVs in areas with high infections significantly reduce the spread of EVD. Model findings emphasise integrating GTVs and population flow management with traditional strategies to strengthen outbreak responses in conflict-prone regions.
{"title":"The impact of geographically-targeted vaccinations during the 2018-2020 Kivu Ebola outbreak","authors":"Suliman Jamiel M. Abdalla , Keshlan S. Govinder , Faraimunashe Chirove","doi":"10.1016/j.apm.2025.115972","DOIUrl":"10.1016/j.apm.2025.115972","url":null,"abstract":"<div><div>The 2018–2020 Ebola virus disease (EVD) outbreak in the Democratic Republic of Congo (DR Congo) was the second-largest in history, mainly because of security challenges and community mistrust. This study evaluates the impact of geographically targeted vaccinations (GTVs) as a complementary strategy when traditional measures—contact tracing, ring vaccinations, and antiviral treatments—are insufficient. We develop a novel mathematical model, incorporating key factors such as transmission from the deceased, heterogeneity in susceptibility, migration patterns, and control measures. Numerical simulations reveal that while traditional control measures substantially reduce cumulative cases to 3500 within one year, compared to over 10 million cases without intervention, population movement into high-infection areas intensifies transmission by increasing the pool of susceptible individuals. This highlights the need to reduce the flow of population into high-risk regions. Sensitivity analysis identifies key parameters, including effective contact rate and the rate of movement into areas with high infections, as critical epidemic drivers. Contour plots demonstrate that GTVs in areas with high infections significantly reduce the spread of EVD. Model findings emphasise integrating GTVs and population flow management with traditional strategies to strengthen outbreak responses in conflict-prone regions.</div></div>","PeriodicalId":50980,"journal":{"name":"Applied Mathematical Modelling","volume":"142 ","pages":"Article 115972"},"PeriodicalIF":4.4,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143035291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号