检索结果-内蒙古大学图书馆

Highly efficient and extensible parallel topology optimization for continuous fiber reinforced composites

COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2025年 436卷

作者： Li, Guixing Chen, Yuan Southern Univ Sci & Technol Shenzhen Key Lab Intelligent Mfg Continuous Carbon Shenzhen 518055 Peoples R China Southern Univ Sci & Technol Sch Syst Design & Intelligent Mfg SDIM Shenzhen 518055 Peoples R China

The optimal design of continuous fiber reinforced composites (CFRC) is crucial for enhancing the lightweight and mechanical performance of high-end equipment structures. This research introduces an innovative parallel optimization framework, referred to as level-set and stream function based parallel topology optimization (LSPTO), for optimizing CFRC structures. In LSPTO, the level-set function and stream function are well integrated to calculate the structural topology and continuous fiber paths, respectively. Compactly supported radial basis functions are utilized to parameterize the structural description functions, enabling the development of design variables. Building on LSPTO, this article presents a general form of sensitivity information. This aids in addressing optimization of the design of CFRC across various objectives. Stiffness optimization cases demonstrate the effectiveness of LSPTO and its advantages in computational efficiency. This parallel numerical framework can efficiently produce clear structural topologies and high-quality fiber paths (e.g., continuous, smooth, non-crossing, and of equal width). Further, the extensibility of the LSPTO framework is investigated considering manufacturing constraints (i.e., fiber paths spacing and fiber volume fraction) for practical applications, i.e., additive manufacturing. By incorporating two constraints related to the gradient of the stream function into the LSPTO framework, the controllable fiber path spacing, regulation of fiber volume fraction, and variable fiber density of CFRC can be well achieved. Compared with the recently developed uniform fiber density method, LSPTO can attain a more effective distribution of fiber paths and significantly enhance structural performance while adhering to manufacturing constraints. The proposed method is highly efficient and easily extensible in the design of CFRC and lays a foundation in the integrated design and manufacturing of CFRC.

关键词： Continuous fiber reinforced composite Parallel optimization level-set function Stream function Integrated optimization

来源：评论

学校读者我要写书评

暂无评论

Deep LBLS: Accelerated Sky Region Segmentation Using Hybrid Deep CNNs and Lattice Boltzmann level-set Model

ENG

引用

ENG 2025年第3期6卷

作者： Albalooshi, Fatema A. Qader, M. R. Ismail, Yasser Elmedany, Wael Al-Ammal, Hesham Rajarajan, Muttukrishnan Asari, Vijayan K. Univ Bahrain Coll Informat Technol POB 32038 Sakhir Bahrain Univ Bahrain Coll Engn POB 32038 Sakhir Bahrain Southern Univ & Coll A&M Dept Elect & Comp Engn Baton Rouge LA 70813 USA City St Georges Univ London Sch Sci & Technol London EC1V 0HB England Univ Dayton Sch Engn Dept Elect & Comp Engn Dayton OH 45469 USA

Accurate segmentation of the sky region is crucial for various applications, including object detection, tracking, and recognition, as well as augmented reality (AR) and virtual reality (VR) applications. However, sky region segmentation poses significant challenges due to complex backgrounds, varying lighting conditions, and the absence of clear edges and textures. In this paper, we present a new hybrid fast segmentation technique for the sky region that learns from object components to achieve rapid and effective segmentation while preserving precise details of the sky region. We employ Convolutional Neural Networks (CNNs) to guide the active contour and extract regions of interest. Our algorithm is implemented by leveraging three types of CNNs, namely DeepLabV3+, Fully Convolutional Network (FCN), and SegNet. Additionally, we utilize a local image fitting level-set function to characterize the region-based active contour model. Finally, the Lattice Boltzmann approach is employed to achieve rapid convergence of the level-set function. This forms a deep Lattice Boltzmann level-set (deep LBLS) segmentation approach that exploits deep CNN, the level-set method (LS), and the lattice Boltzmann method (LBM) for sky region separation. The performance of the proposed method is evaluated on the CamVid dataset, which contains images with a wide range of object variations due to factors such as illumination changes, shadow presence, occlusion, scale differences, and cluttered backgrounds. Experiments conducted on this dataset yield promising results in terms of computation time and the robustness of segmentation when compared to state-of-the-art methods. Our deep LBLS approach demonstrates better performance, with an improvement in mean recall value reaching up to 14.45%.

关键词： deep learning convolutional neural networks (CNNs) DeepLabV3+ fully convolutional network (FCN) SegNet level-set function lattice Boltzmann method (LBM) sky object segmentation

来源：评论

学校读者我要写书评

暂无评论

Implementation of Dynamic Programming for n-Dimensional Optimal Control Problems With Final State Constraints

引用

IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY 2013年第3期21卷 924-931页

作者： Elbert, Philipp Ebbesen, Soren Guzzella, Lino ETH Dept Mech & Proc Engn CH-8092 Zurich Switzerland

Many optimal control problems include a continuous nonlinear dynamic system, state, and control constraints, and final state constraints. When using dynamic programming to solve such a problem, the solution space typically needs to be discretized and interpolation is used to evaluate the cost-to-go function between the grid points. When implementing such an algorithm, it is important to treat numerical issues appropriately. Otherwise, the accuracy of the found solution will deteriorate and global optimality can be restored only by increasing the level of discretization. Unfortunately, this will also increase the computational effort needed to calculate the solution. A known problem is the treatment of states in the time-state space from which the final state constraint cannot be met within the given final time. In this brief, a novel method to handle this problem is presented. The new method guarantees global optimality of the found solution, while it is not restricted to a specific class of problems. Opposed to that, previously proposed methods either sacrifice global optimality or are applicable to a specific class of problems only. Compared to the basic implementation, the proposed method allows the use of a substantially lower level of discretization while achieving the same accuracy. As an example, an academic optimal control problem is analyzed. With the new method, the evaluation time was reduced by a factor of about 300, while the accuracy of the solution was maintained.

关键词： Backward reachability curse of dimensionality dynamic programming (DP) level-set function

来源：评论

学校读者我要写书评

暂无评论

Numerical simulation of drops inside an asymmetric microchannel with protrusions

引用

COMPUTERS & FLUIDS 2013年 82卷 14-28页

作者： Yin, Bo Luo, Haoxiang Vanderbilt Univ Dept Mech Engn Nashville TN 37235 USA

Microfluidic channels with asymmetric protrusions have been utilized previously to enhance mixing in the drops that travel through the channels. To study the flow pattern in the drops and help explain the mixing phenomenon, in this work an immersed-boundary method is developed to simulate dynamics of a drop in arbitrary channel geometries. In this method, the fluid-solid interface is handled, by the sharp-interface approach in which the interface maintains its singularity and the boundary conditions are satisfied at the exact location of the interface. On the other hand, the fluid-fluid interface is handled by a diffuse-interface approach in which the interfacial discontinuities are regularized by an approximated delta function. The simulation results show that for the drop in a channel with bumps on one side, the flow pattern inside the drop largely depends on the viscosity ratio and the geometry of the bumps. When the viscosity ratio or the curvature of the bumps is increased, the vortex pair inside the drop become skewed or even reduce to one single circulation. In three dimensions, the circulations in the spanwise direction are also developed. The mixing enhancement of these flow patterns is demonstrated by simulating the passive tracers in the drop. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Mixing Drops Two-phase flow Channel flow Immersed-boundary method level-set function Complex geometries

来源：评论

学校读者我要写书评

暂无评论

Adjoint-based shape optimization for radiative transfer in porous structure for volumetric solar receiver

引用

APPLIED THERMAL ENGINEERING 2024年 246卷

作者： Liu, Ming Matsubara, Koji Hasegawa, Yosuke Univ Tokyo Inst Ind Sci Meguro Ku 4-6-1 Komaba Tokyo 1538505 Japan Niigata Univ Fac Engn Ikarashi 2 Nocho 8050Nishi Ku Niigata 9502181 Japan

Due to their large surface areas, porous structures are often used for volumetric solar receivers for efficient utilization of the solar energy. However, the precise simulation and optimization of radiative heat transfer inside porous structures are still challenging due to their complex geometries. In the present study, an adjoint-based shape optimization framework for radiative transfer in porous structures is first proposed. Specifically, an arbitrary complex geometry of a porous structure is represented by a level-set function embedded in a Cartesian grid system. The volume penalization method combined with the discrete ordinate method is employed to simulate a forward radiative transfer problem in a porous structure. Then, a cost functional for an adjoint analysis is defined by the volume average of the divergence of the radiative heat flux, which corresponds to the total heat absorbed by the porous structure with a negative sign. The adjoint equations for minimizing the cost functional, and the corresponding shape update formula are derived and implemented in an open-source software, OpenFOAM. The developed adjoint-based shape optimization framework is applied to three types of initial porous structures, i.e., SC Kelvin, BCC Kelvin, and square honeycomb models. For all the initial porous models, the front surface commonly extends towards the direction of the incident radiation, and consequently notable improvements of the absorption efficiency can be achieved through the optimization. In addition, a systematic parametric survey for the initial shape of the SC Kelvin model is conducted to reveal the impacts of the number of unit cells, the solid emissivity, and the solid temperature on the optimal shapes and the resulting absorption efficiencies.

关键词： Adjoint-based topology optimization level-set function Radiative transfer Porous structure Solar receiver

来源：评论

学校读者我要写书评

暂无评论

Quality evaluation of honing surface groove features based on improved level-set analyses

引用

MEASUREMENT 2022年 190卷

作者： Dai, Jiacheng Zeng, Wenhan Lu, Wenlong Wang, Jian Shan, Mingguang Jiang, Xiangqian Huazhong Univ Sci & Technol Sch Mech Sci & Engn State Key Lab Digital Mfg Equipment & Technol Wuhan 430074 Peoples R China Univ Huddersfield EPSRC Future Metrol Hub Huddersfield HD1 3DH W Yorkshire England Harbin Engn Univ Coll Informat & Commun Engn Harbin 150001 Peoples R China HUST Shen Zhen Res Inst Shenzhen 518000 Peoples R China

Honing groove features of a cylinder liner surface contain helpful information on surface performance. Tradi-tional honing surface evaluation methods do not focus on groove features, which is significant to surface functions. Hence, a topographical feature segmentation algorithm and corresponding evaluation parameters are needed. This paper proposes an improved level-set-based segmentation algorithm for groove feature extraction. The proposed algorithm was tested on a real honing surface dataset compared to some state-of-art algorithms, including the classical height thresholding and watershed segmentation. The results show that the proposed method is robust against initial conditions and improves both segmentation accuracy and computational speed. Specifically, a 30% accuracy improvement over the best-tested level-set algorithm has been observed. Another case study on fold-mental characterization was conducted, which also validated the accuracy and speed per-formance of the proposed algorithm.

关键词： level-set function Surface topography Honing groove feature

来源：评论

学校读者我要写书评

暂无评论

A comprehensive study of feature definitions with solids and voids for topology optimization

引用

COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2017年 325卷 289-313页

作者： Zhang, Weihong Zhou, Ying Zhu, Jihong Northwestern Polytech Univ State IJR Ctr Aerosp Design & Addit Mfg Xian 710072 Shaanxi Peoples R China Northwestern Polytech Univ MIIT Lab Met Addit Mfg & Innovat Design Xian 710072 Shaanxi Peoples R China

In this paper, we present a CAD-oriented and feature-driven topology optimization methodology for engineering structures with freeform design domains. Mixed solid-void features are adopted as basic design primitives to build a unified formulation of feature definition, while pure solid or pure void features are considered as two special cases. Topology optimization is achieved as a Boolean intersection process between the so-called topology variation modeler (TVM) and freeform design domain modeler (FDDM) in terms of level-set functions (LSFs). The TVMs constructed with solid and/or void features are applied to clip the FDDM through Boolean operations. It is shown that sensitivity analysis with boundary integral scheme is independent of the mathematical expressions of the LSF. Numerical problems with freeform and periodic design domains are dealt with to demonstrate the proposed topology optimization method. (C) 2017 Elsevier B.V. All rights reserved.

关键词： Computer-aided design Topology optimization Feature-based design Topology variation modeler Freeform design domain modeler level-set function

来源：评论

学校读者我要写书评

暂无评论

CBS-based topology optimization including design-dependent body loads

引用

COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2017年 322卷 1-22页

作者： Zhang, Weihong Zhao, Linying Gao, Tong Northwestern Polytech Univ Sch Mech Engn Engn Simulat & Aerosp Comp ESAC Xian 710072 Shaanxi Peoples R China

In this paper, the inherent problem of the so-called parasitic effect of low density region caused by design-dependent loads is investigated for topology optimization. A CBS (closed B-splines)-based method is developed to solve efficiently the problem in the way of shape optimization. Compared to the standard density method, design variables are unattached to the finite element model and defined by control parameters dominating the parametric equation of the CBS. As a result, design-dependent loads associated with the material layout of a structure are made change indirectly by the boundary variation of the structure. To favour structural reanalyses and sensitivity analysis, the implicit form of the CBS, i.e., level-set function (LSF) is used in conjunction with the fixed computing grid of finite cell method (FCM). A variety of design-dependent body loads is considered for the mathematical formulation of the CBS-based method. Typical examples are given to illustrate that the CBS-based method is free of low density regions in the optimized topology owing to the proper definitions of design variables. (C) 2017 Elsevier B.V. All rights reserved.

关键词： Closed B-splines Design-dependent loads Finite cell method level-set function Topology optimization

来源：评论

学校读者我要写书评

暂无评论

Evolutionary topology optimization of continuum structures with smooth boundary representation

引用

STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION 2018年第6期57卷 2143-2159页

作者： Da, Daicong Xia, Liang Li, Guangyao Huang, Xiaodong Hunan Univ State Key Lab Adv Design & Mfg Vehicle Body Changsha Hunan Peoples R China Collaborat Innovat Ctr Intelligent New Energy Veh Shanghai 200092 Peoples R China Huazhong Univ Sci & Technol State Key Lab Digital Mfg Equipment & Technol Wuhan Hubei Peoples R China Swinburne Univ Technol Fac Sci Engn & Technol Melbourne Vic 3122 Australia

This paper develops an extended bi-directional evolutionary structural optimization (BESO) method for topology optimization of continuum structures with smoothed boundary representation. In contrast to conventional zigzag BESO designs and removal/addition of elements, the newly proposed evolutionary topology optimization (ETO) method, determines implicitly the smooth structural topology by a level-set function (LSF) constructed by nodal sensitivity numbers. The projection relationship between the design model and the finite element analysis (FEA) model is established. The analysis of the design model is replaced by the FEA model with various elemental volume fractions, which are determined by the auxiliary LSF. The introduction of sensitivity LSF results in intermediate volume elements along the solid-void interface of the FEA model, thus contributing to the better convergence of the optimized topology for the design model. The effectiveness and robustness of the proposed method are verified by a series of 2D and 3D topology optimization design problems including compliance minimization and natural frequency maximization. It has been shown that the developed ETO method is capable of generating a clear and smooth boundary representation;meanwhile the resultant designs are less dependent on the initial guess design and the finite element mesh resolution.

关键词： Topology optimization Evolutionary topology optimization (ETO) level-set function Smooth boundary representation

来源：评论

学校读者我要写书评

暂无评论

Simulation of compressible two-phase flows with topology change of fluid-fluid interface by a robust cut-cell method

引用

JOURNAL OF COMPUTATIONAL PHYSICS 2017年 328卷 140-159页

作者： Lin, Jian-Yu Shen, Yi Ding, Hang Liu, Nan-Sheng Lu, Xi-Yun Univ Sci & Technol China Dept Modern Mech Hefei 230027 Peoples R China

We develop a robust cut-cell method for numerical simulation of compressible two-phase flows with topology change of the fluid-fluid interface. In cut cell methods the flows can be solved in the finite volume framework and the jump conditions at the interface are resolved by solving a local Riemann problem. Therefore, cut cell methods can obtain interface evolution with high resolution, and at the same time satisfactorily maintain the conservation of flow quantities. However, it remains a challenge for the cut cell methods to handle interfaces with topology change or very high curvature, where the mesh is not sufficiently fine to resolve the interface. Inappropriate treatment could give rise to either distorted interface advection or unphysical oscillation of flow variables, especially when the regularization process (e.g. reinitialization in the level set methods) is implemented. Arobust cut-cell method is proposed here, with the interface being tracked by a level set function. The local unphysical oscillation of flow variables in the presence of topology change is shown to be greatly suppressed by using a delayed reinitialization. The method can achieve second-order accuracy with respect to the interface position in the absence of topology changes of interface, while locally degrading to first-order at the interface region where topology change occurs. Its performance is examined through a variety of numerical tests, such as Rayleigh collapse, shock-bubble interaction, and shock-induced bubble collapse in water. Numerical results are compared against either benchmark solutions or experimental observations, and good agreement has been achieved qualitatively and/or quantitatively. Finally, we apply the method to investigating the collapse process of two tandem bubbles in water. (C) 2016 Elsevier Inc. All rights reserved.

关键词： Cut-cell method level-set function Sharp-interface method Compressible two-phase flows

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：