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  Subjects -> ENGINEERING (Total: 1962 journals)
    - CHEMICAL ENGINEERING (151 journals)
    - CIVIL ENGINEERING (149 journals)
    - ELECTRICAL ENGINEERING (82 journals)
    - ENGINEERING (1119 journals)
    - ENGINEERING MECHANICS AND MATERIALS (290 journals)
    - HYDRAULIC ENGINEERING (45 journals)
    - INDUSTRIAL ENGINEERING (52 journals)
    - MECHANICAL ENGINEERING (74 journals)

CIVIL ENGINEERING (149 journals)                  1 2     

ACI Structural Journal     Full-text available via subscription   (Followers: 4)
Acta Polytechnica : Journal of Advanced Engineering     Open Access  
Acta Structilia : Journal for the Physical and Development Sciences     Open Access   (Followers: 2)
Advances in Civil Engineering     Open Access   (Followers: 22)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 18)
Ambiente Construído     Open Access   (Followers: 2)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 15)
Architectural Engineering     Open Access   (Followers: 3)
Archives of Civil Engineering     Open Access   (Followers: 6)
Archives of Hydro-Engineering and Environmental Mechanics     Open Access   (Followers: 2)
ATBU Journal of Environmental Technology     Open Access  
Australian Journal of Structural Engineering     Full-text available via subscription   (Followers: 2)
Baltic Journal of Road and Bridge Engineering     Full-text available via subscription  
BER : Building and Construction : Full Survey     Full-text available via subscription   (Followers: 8)
BER : Building Contractors' Survey     Full-text available via subscription   (Followers: 3)
BER : Building Sub-Contractors' Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Building and Construction : An Executive Summary     Full-text available via subscription   (Followers: 4)
Berkeley Planning Journal     Open Access   (Followers: 5)
Bridge Structures : Assessment, Design and Construction     Hybrid Journal   (Followers: 10)
Building and Environment     Hybrid Journal   (Followers: 10)
Building Women     Full-text available via subscription  
Built Environment Project and Asset Management     Hybrid Journal   (Followers: 12)
Canadian Journal of Civil Engineering     Full-text available via subscription   (Followers: 10)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 3)
Cement and Concrete Composites     Hybrid Journal   (Followers: 6)
Change Over Time     Full-text available via subscription   (Followers: 3)
Civil and Environmental Research     Open Access   (Followers: 11)
Civil Engineering     Hybrid Journal   (Followers: 9)
Civil Engineering = Siviele Ingenieurswese     Full-text available via subscription   (Followers: 4)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 4)
Civil Engineering and Technology     Open Access   (Followers: 1)
Civil Engineering Dimension     Open Access   (Followers: 3)
Cohesion and Structure     Full-text available via subscription   (Followers: 1)
Composite Structures     Hybrid Journal   (Followers: 33)
Computer-aided Civil and Infrastructure Engineering     Hybrid Journal   (Followers: 7)
Computers & Structures     Hybrid Journal   (Followers: 13)
Concrete Research Letters     Open Access   (Followers: 1)
Constructii : Journal of Civil Engineering Research     Open Access   (Followers: 4)
Construction Engineering     Open Access   (Followers: 3)
Construction Management and Economics     Hybrid Journal   (Followers: 25)
Construction Science     Open Access   (Followers: 1)
Constructive Approximation     Hybrid Journal  
Current Advances in Civil Engineering     Open Access  
Earthquake Engineering and Structural Dynamics     Hybrid Journal   (Followers: 10)
Enfoque UTE     Open Access   (Followers: 1)
Engineering Project Organization Journal     Hybrid Journal   (Followers: 4)
Engineering Structures     Hybrid Journal   (Followers: 11)
Engineering Structures and Technologies     Hybrid Journal   (Followers: 2)
Engineering, Construction and Architectural Management     Hybrid Journal   (Followers: 16)
Environmental Geotechnics     Open Access  
European Journal of Environmental and Civil Engineering     Hybrid Journal   (Followers: 2)
Fatigue & Fracture of Engineering Materials and Structures     Hybrid Journal   (Followers: 12)
Frattura ed Integrità Strutturale : Fracture and Structural Integrity     Open Access   (Followers: 1)
Frontiers of Structural and Civil Engineering     Hybrid Journal   (Followers: 4)
Geomaterials     Open Access   (Followers: 2)
Geosystem Engineering     Hybrid Journal   (Followers: 3)
Geotechnik     Hybrid Journal  
Géotechnique Letters     Hybrid Journal   (Followers: 1)
HBRC Journal     Open Access   (Followers: 1)
HVAC&R Research     Hybrid Journal   (Followers: 1)
Indoor and Built Environment     Hybrid Journal   (Followers: 1)
Ingenio Magno     Open Access  
Insight - Non-Destructive Testing and Condition Monitoring     Full-text available via subscription   (Followers: 4)
International Journal for Service Learning in Engineering     Open Access  
International Journal of 3-D Information Modeling     Full-text available via subscription   (Followers: 2)
International Journal of Advanced Structural Engineering     Open Access   (Followers: 6)
International Journal of Concrete Structures and Materials     Open Access   (Followers: 5)
International Journal of Construction Engineering and Management     Open Access   (Followers: 3)
International Journal of Protective Structures     Full-text available via subscription   (Followers: 5)
International Journal of Steel Structures     Hybrid Journal   (Followers: 3)
International Journal of Structural Engineering     Hybrid Journal   (Followers: 6)
International Journal of Structural Integrity     Hybrid Journal  
International Journal of Structural Stability and Dynamics     Hybrid Journal   (Followers: 4)
International Journal of Sustainable Built Environment     Open Access   (Followers: 2)
International Journal of Sustainable Construction Engineering and Technology     Open Access   (Followers: 7)
ISRN Civil Engineering     Open Access   (Followers: 4)
ISRN Power Engineering     Open Access   (Followers: 1)
Journal of Accessibility and Design for All     Open Access   (Followers: 3)
Journal of Applied Fire Science     Full-text available via subscription  
Journal of Bridge Engineering     Full-text available via subscription   (Followers: 13)
Journal of Building Performance Simulation     Hybrid Journal   (Followers: 3)
Journal of Civil Engineering and Construction Technology     Open Access   (Followers: 2)
Journal of Civil Engineering and Management     Hybrid Journal   (Followers: 4)
Journal of Civil Engineering and Science     Open Access   (Followers: 9)
Journal of Civil Engineering Research     Open Access   (Followers: 9)
Journal of Civil Society     Hybrid Journal   (Followers: 2)
Journal of Civil Structural Health Monitoring     Hybrid Journal  
Journal of Composites     Open Access   (Followers: 6)
Journal of Composites for Construction     Full-text available via subscription   (Followers: 8)
Journal of Computing in Civil Engineering     Full-text available via subscription   (Followers: 17)
Journal of Construction Engineering     Open Access   (Followers: 3)
Journal of Construction Engineering and Management     Full-text available via subscription   (Followers: 20)
Journal of Construction Engineering, Technology & Management     Full-text available via subscription   (Followers: 3)
Journal of Constructional Steel Research     Hybrid Journal   (Followers: 6)
Journal of Earth Sciences and Geotechnical Engineering     Open Access   (Followers: 1)
Journal of Fluids and Structures     Hybrid Journal   (Followers: 2)
Journal of Frontiers in Construction Engineering     Open Access   (Followers: 1)
Journal of Green Building     Full-text available via subscription   (Followers: 6)
Journal of Highway and Transportation Research and Development (English Edition)     Full-text available via subscription   (Followers: 4)
Journal of Infrastructure Systems     Full-text available via subscription   (Followers: 13)

        1 2     

Journal Cover Structural and Multidisciplinary Optimization
   [5 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1615-1488 - ISSN (Online) 1615-147X
     Published by Springer-Verlag Homepage  [2209 journals]   [SJR: 1.273]   [H-I: 54]
  • Cost-weight trades for modular composite structures
    • Abstract: Abstract A design approach for airframe structures is formulated based on the concept of modularity allowing trade-offs and optimization between cost and weight. A modular structure can be created by replacing a collection of parts which all have a unique design by a collection of parts where the same design repeats multiple times. Structures with high levels of modularity have higher weight since it is harder to design a weight-efficient structure when the amount of design options is limited, but this weight increase might be worth the associated decrease in manufacturing cost. In modular design, cost reductions are achieved through learning curve effects and through reduction of the non-recurring cost, for example, due to lower tooling costs. Based on dynamic programming, an approach to determine the optimum number of repeating designs was determined and applied to a composite fuselage structure. Two examples are given where the cost-weight efficiency at different modularity levels is assessed for a composite airframe: the stringers and the frames in a fuselage. The corresponding cost-weight diagrams indicated that the modularity concept provides a useful methodology for designing more cost- weight efficient structures. In both cases it was possible to replace a large amount of designs and increase the level of modularity of the structure, yielding significant reductions in recurring and non-recurring manufacturing costs while keeping the associated weight increase of the structure to a minimum.
      PubDate: 2014-06-01
       
  • Simultaneous optimization of shape parameters and weight factors in
           ensemble of radial basis functions
    • Abstract: Abstract Radial basis functions (RBFs) are approximate mathematical models that can mimic the behavior of fast changing responses. Different formulations of RBFs can be combined in the form of an ensemble model to improve prediction accuracy. The conventional approach in constructing an RBF ensemble is based on a two-step procedure. In the first step, the optimal values of the shape parameters of each stand-alone RBF model are determined. In the second step, the shape parameters are fixed to these optimal values and the weight factors of each stand-alone RBF model in the ensemble are optimized. In this paper, simultaneous optimization of shape parameters and weight factors is proposed as an alternative to this two-step procedure for further improvement of prediction accuracy. Gaussian, multiquadric and inverse multiquadric RBF formulations are combined in the ensemble model. The efficiency of the proposed method is evaluated through example problems of varying dimensions from two to twelve. It is found that the proposed method improves the prediction accuracy of the ensemble compared to the conventional two-step procedure for the example problems considered.
      PubDate: 2014-06-01
       
  • Shape optimization for the generalized Graetz problem
    • Abstract: Abstract We apply shape optimization tools to the generalized Graetz problem which is a convection-diffusion equation. The problem boils down to the optimization of generalized eigenvalues on a two phases domain. Shape sensitivity analysis is performed with respect to the evolution of the interface between the fluid and solid phase. In particular physical settings, counterexamples where there is no optimal domains are exhibited. Numerical examples of optimal domains with different physical parameters and constraints are presented. Two different numerical methods (level-set and mesh-morphing) are show-cased and compared.
      PubDate: 2014-06-01
       
  • Airfoil shape optimization using improved Multiobjective Territorial
           Particle Swarm algorithm with the objective of improving stall
           characteristics
    • Abstract: Abstract In this paper, a new robust optimization technique with the ability of solving multi-objective constrained design optimization problems in aerodynamics is presented. This new technique is Multi-objective Territorial Particle Swarm Optimization (MOTPSO) algorithm in which diversity is actively preserved by avoiding overcrowded clusters of particles and encouraging broader exploration. Adaptively varying “territories” are formed around promising individuals to prevent many of the lesser individuals from premature clustering and encouraged them to explore new neighborhoods based on a hybrid self-social metric. Also, a new social interaction scheme is introduced which guided particles towards the weighted average of their “elite” neighbors’ best found positions instead of their own personal bests which in turn helps the particles to exploit the candidate local optima more effectively. The MOTPSO algorithm takes into account multiple objective functions using a Pareto-Based approach. The non-dominated solutions found by swarm are stored in an external archive and nearest neighbor density estimator method is used to select a leader for the individual particles in the swarm. Efficiency and robustness of the proposed algorithm is demonstrated using multiple traditional and newly-composed optimization benchmark functions and aerodynamic design problems. In final airfoil designs obtained from the Multi Objective Territorial Particle Swarm Optimization algorithm, separation point is delayed to make the airfoil less susceptible to stall in critical operating conditions and it also reveal an evident improvement over the test case airfoil across all objective functions presented.
      PubDate: 2014-06-01
       
  • A general purpose real-world structural design optimization computing
           platform
    • Abstract: Abstract Structural optimization has matured from a narrow academic discipline, where researchers focused on optimum design of small idealized structural components and systems, to become the basis in modern design of complex structural systems. Some software applications in recent years have made these tools accessible to professional engineers, decision-makers and students outside the structural optimization research community. These software applications, mainly focused on aerospace, aeronautical, mechanical and naval structural systems, have incorporated the optimization component as an additional feature of the finite element software package. On the other hand though there is not a holistic optimization approach in terms of final design stage for real-world civil engineering structures such as buildings, bridges or more complex civil engineering structures. The optimization computing platform presented in this study is a generic real-world optimum design computing platform for civil structural systems and it is implemented within an innovative computing framework, founded on the current state of the art in topics like metaheuristic optimization, structural analysis and parallel computing. For demonstration purposes the application of the optimization computing platform in five real-world design projects is presented.
      PubDate: 2014-06-01
       
  • A consistent frame for sensitivity filtering and the vertex assigned
           morphing of optimal shape
    • Abstract: Abstract The paper discusses the filtering of shape sensitivities as a mesh independent regularization method for very large problems of shape optimal design. The vertices of the simulation discretization grids are directly used as design morphing handles allowing for the largest possible design space. Still, however, there has been a lack of theory to consistently merging the sensitivity filtering into the standard optimization technology which is an ongoing topic of discussion in the community. The actual paper tries to overcome this burden. As a result it will be shown that there is a perfect transition between the sensitivity filtering and all the other shape parameterization techniques used for the shape optimization, as there are CAD-based techniques, subdivision surfaces or morphing box technologies. It appears that sensitivity filtering belongs to the most general and powerful control technologies available for shape optimal design. The success will be demonstrated by various illustrative examples which span from basic aspects to sophisticated applications in structural and fluid mechanics.
      PubDate: 2014-06-01
       
  • The use of topology optimization in disposing carbon fiber reinforcement
           for concrete structures
    • Abstract: Abstract A topology optimization procedure is presented as a tool for determining the distribution of external strengthening of concrete slabs, using Carbon Fiber Reinforced Polymer (CFRP). Although the procedure is applied to slabs in this work, the technique can be used in any concrete structure to be reinforced. Numerical simulations are performed using the Finite Element Method, in combination with the automated topology optimization procedure, to indicate the optimal region for placement of the reinforcement. The influence of some aspects of the slab’s structural behavior on the optimization results is presented: concrete cracking, boundary conditions and reinforcement rate. A brief discussion is given of the similarity between the topology optimization results obtained by the maximum stiffness and ultimate strength criteria. Gains are found in the stiffness and strength of reinforced parts. A comparison with conventional reinforcement techniques demonstrates that topology optimization can be a useful tool for defining the region of reinforcement, allowing for material cost savings.
      PubDate: 2014-06-01
       
  • Metamodel-assisted optimization based on multiple kernel regression for
           mixed variables
    • Abstract: Abstract While studies in metamodel-assisted optimization predominantly involve continuous variables, this paper explores the additional presence of categorical data, representing for instance the choice of a material or the type of connection. The common approach consisting in mapping them onto integers might lead to inconsistencies or poor approximation results. Therefore, an investigation of the best coding is necessary; however, to build accurate and flexible metamodels, a special attention should also be devoted to the treatment of the distinct nature of the variables involved. Consequently, a multiple kernel regression methodology is proposed, since it allows for selecting separate kernel functions with respect to the variable type. The validation of the advocated approach is carried out on six analytical benchmark test cases and on the structural responses of a rigid frame. In all cases, better performances are obtained by multiple kernel regression with respect to its single kernel counterpart, thereby demonstrating the potential offered by this approach, especially in combination with dummy coding. Finally, multi-objective surrogate-based optimization is performed on the rigid frame example, firstly to illustrate the benefit of dealing with mixed variables for structural design, then to show the reduction in terms of finite element simulations obtained thanks to the metamodels.
      PubDate: 2014-06-01
       
  • Robust optimization of foam-filled thin-walled structure based on
           sequential Kriging metamodel
    • Abstract: Abstract Deterministic optimization has been successfully applied to a range of design problems involving foam-filled thin-walled structures, and to some extent gained significant confidence for the applications of such structures in automotive, aerospace, transportation and defense industries. However, the conventional deterministic design could become less meaningful or even unacceptable when considering the perturbations of design variables and noises of system parameters. To overcome this drawback, a robust design methodology is presented in this paper to address the effects of parametric uncertainties of foam-filled thin-walled structure on design optimization, in which different sigma criteria are adopted to measure the variations. The Kriging modeling technique is used to construct the corresponding surrogate models of mean and standard deviation for different crashworthiness criteria. A sequential sampling approach is introduced to improve the fitness accuracy of these surrogate models. Finally, a gradient-based sequential quadratic program (SQP) method is employed from 20 different initial points to obtain a quasi-global robust optimum solution. The optimal solutions were verified by using the Monte Carlo simulation. The results show that the presented robust optimization method is fairly effective and efficient, the crashworthiness and robustness of the foam-filled thin-walled structure can be improved significantly.
      PubDate: 2014-06-01
       
  • Stress constrained compliance minimization by means of the small amplitude
           homogenization method
    • Abstract: Abstract Under the assumption of small contrast between the elasticity tensors of two materials, we derive an algorithm based on an approximate relaxation of a problem that minimizes the compliance under a constraint on stress. Numerical results are presented for the short cantilever problem, where we see that, for a 1 to 2 contrast in Young moduli, and when compared with a configuration that only minimizes compliance, one can get up to a 46 % reduction in peak stress, while compliance increases by only 1 %. The basis of the method is the small amplitude homogenization technique derived by Allaire and Gutiérrez, which relies on the use of H-measures introduced by Tartar to study the quadratic interaction of weakly convergent sequences of functions.
      PubDate: 2014-06-01
       
  • A reanalysis method for local modification and the application in
           large-scale problems
    • Abstract: Abstract A novel reanalysis method, named independent coefficients (IC) method is suggested in this study. This method is proposed to reanalyze structures with local modification which leads to a low-rank change in the stiffness matrix. IC method requires only initial solution as input, and can determine the independent coefficients for each degree of freedoms (DOFs) influenced by structural modifications. Since any extra operations such as decomposition of the initial stiffness matrix is not involved in computation procedure, the IC is a “cheap” algorithm and can be an alternative choice for reanalysis. In order to verify the performance of IC method, several large scale numerical examples are tested. The results demonstrate that the IC method has high accuracy as well as efficiency when the modification is local. The cases involving beyond 1,500,000 DOFs and 3,000,000 DOFs show that IC method has low demands on computer storage, and large scale problems can be easily reanalyzed by this method.
      PubDate: 2014-06-01
       
  • Form finding & structural optimization
    • Abstract: Abstract Nowadays, accreditation organizations for engineering programs put more and more emphasis on learning outcomes integrating multifaceted competences (scientific and technical skills, but also teamwork, communication, etc.). In this context, this paper discusses the relevance of project-based learning initiatives for teaching structural optimization, in the light of recent literature on the subject, as well as based on our experience in a course on form finding and structural optimization at the Brussels Faculty of Engineering. Although each project-based course has its specificities related to the teachers, their expertise, and the curriculum philosophy, some general guidelines are proposed, stressing the importance of a proper understanding of the mathematical and physical concepts, but also underlining the need to ensure sufficient room for creativity among the students.
      PubDate: 2014-06-01
       
  • Multidisciplinary multifidelity optimisation of a flexible wing aerofoil
           with reference to a small UAV
    • Abstract: Abstract The preliminary Multidisciplinary Design and Optimisation of a flexible wing aerofoil apropos a small Unmanned Air Vehicle is performed using a multifidelity model-based strategy. Both the passively adaptive structure and the shape of the flexible wing aerofoil are optimised for best aerodynamic performance under aero-structural constraints, within a coupled aeroelastic formulation. A typical flight mission for surveillance purposes is considered and includes the potential occurrence of wind gusts. A metamodel for the high-fidelity objective function and each of the constraints is built, based on a tuned low-fidelity one, in order to improve the efficiency of the optimisation process. Both metamodels are based on solutions of the aeroelastic equations for a flexible aerofoil but employ different levels of complexity and computational cost for modelling aerodynamics and structural dynamics within a modal approach. The high-fidelity model employs nonlinear Computational Fluid Dynamics coupled with a full set of structural modes, whereas the low-fidelity one employs linear thin aerofoil theory coupled with a reduced set of structural modes. The low-fidelity responses are then corrected according to few high-fidelity responses, as prescribed by an appropriate Design of Experiment, by means of a suitable tuning technique. A standard Genetic Algorithm is hence utilised to find the global optimum, showing that a flexible aerofoil is characterised by higher aerodynamic efficiency than its rigid counterpart. Wing weight reduction is also accomplished when a Multiobjective Genetic Algorithm is adopted.
      PubDate: 2014-05-21
       
  • Reallocation of testing resources in validating optimal designs using
           local domains
    • Abstract: Abstract We have recently proposed a new method for integrating design optimization with model validation by means of a sequential approach that uses variable-size local domains of the design space and statistical bootstrap techniques. Our work was motivated by the fact that global model validation may be neither affordable nor necessary. The method proceeds iteratively by obtaining test data at a design point, constructing around it a local domain in which the model is considered valid, and optimizing the design within this local domain. Due to test variability, it is important to know how many tests are needed to size each local domain of the sequential optimization process. Conducting an unnecessarily large number of tests may be inefficient, while a small number of tests may be insufficient to achieve the desired validity level. In this paper, we introduce a technique to determine the number of tests required to account for their variability by sizing the local domains accordingly. The goal is to achieve a desired level of model validity in each domain using the correlation between model data at the center and any other point in the local domain. To make the method more cost-effective we avoid generating some testsby statistically predicting a set of local domains along the optimization process. The proposed technique is illustrated with a piston design example.
      PubDate: 2014-05-16
       
  • Topology optimization of electrode coverage of piezoelectric thin-walled
           structures with CGVF control for minimizing sound radiation
    • Abstract: Abstract It is impractical to implement arbitrary-shaped piezoelectric patches from the view point of manufacturability of fragile piezoelectric ceramics, thus using designable electrode layers to deliver desired actuation forces provides a more realistic option in engineering applications. This study develops a topological design method of surface electrode distribution over piezoelectric sensors/actuators attached to a thin-walled shell structure for reducing the sound radiation in an unbounded acoustic domain. In the optimization model, the sound pressure norm at specific reference points under excitations at a certain excitation frequency or in a given frequency range is taken as the objective function. The pseudo densities for indicating absence and presence of surface electrodes at each element are taken as the design variables, and a penalized relationship between the densities and the active damping effect is employed. The vibrating structure is discretized with finite element model for the frequency response analysis and the sound radiation analysis in the unbounded acoustic domain is treated by boundary element method. The applied voltage on each actuator is determined by the constant gain velocity feedback (CGVF) control law. The technique of the complex mode superposition in the state space, in conjunction with a model reduction transformation, is adopted in the response analysis of the system characterized by a non-proportional active damping property. In this context, the adjoint-variable sensitivity analysis scheme is derived. The effectiveness and efficiency of the proposed method are demonstrated by numerical examples, and several key factors on the optimal designs are also discussed.
      PubDate: 2014-05-15
       
  • Finite element analysis of no–tension structures as a topology
           optimization problem
    • Abstract: Abstract An alternative numerical approach is presented for the analysis of no–tension masonry–like solids. Whereas most of the strategies available in the literature resort to non–linear finite element techniques, the proposed approach re–formulates the problem within the framework of topology optimization. The equilibrium of a two–dimensional no–tension body is found searching for the distribution of an equivalent orthotropic material, in which tensile principal stresses are not allowed by prescribing negligible stiffness in the relevant direction, such that the potential energy of the solid is minimized. Unlike many conventional approaches that deal with the tough non–linearity of the problem through step–wise incremental analyses, the proposed method efficiently solves the effect of compatible loads through a one–shot energy–based optimization. Analytical and numerical benchmarks from the literature are investigated to assess the effectiveness of the proposed procedure and to discuss convergence features and possible applications inspired by the limit analysis of masonry–like structures.
      PubDate: 2014-05-13
       
  • Topology optimization for light-trapping structure in solar cells
    • Abstract: Abstract The limitation associated with the low optical absorption remains to be the main technical barrier that constrains the efficiency of thin–film solar cells in energy conversion. Effective design of light-trapping structure is critical to increase light absorption, which is a highly complex phenomenon governed by several competing physical processes, imposing a number of challenges to topology optimization. This paper presents a general, yet systematic approach exploiting topology optimization for designing highly efficient light-trapping structures. We first demonstrate the proposed approach using genetic algorithm (GA) based non-gradient topology optimization (NGTO), which is robust for achieving highly-efficient designs of slot-waveguide based cells with both low-permittivity and high-permittivity scattering material at single wavelength or over a broad spectrum. The optimized light-trapping structure achieves a broadband absorption efficiency of 48.1 % and more than 3-fold increase over the Yablonovitch limit. The fabrication feasibility of the optimized design is also demonstrated. Next, the gradient topology optimization (GTO) approach for designing light-trapping structure is explored based on the Solid Isotropic Material with Penalization (SIMP) method. Similar designs are obtained through both GA based NGTO and SIMP based GTO, which verifies the validity of both approaches. Insights into the application of both approaches for solving the nanophotonic design problem with optimization nonlinearity are provided.
      PubDate: 2014-05-10
       
  • Topology design of inductors in electromagnetic casting using level-sets
           and second order topological derivatives
    • Abstract: Abstract We propose a new iterative method for the topology design of the inductors in electromagnetic casting. The method is based on a level-set representation of the solution together with first and second order topological derivatives. The optimal design is found by minimizing a Kohn–Vogelius-type functional for the problem. The complete topological expansion of the objective functional, which is herein given, is used to define the iterative step. Results for several numerical examples show that the technique proposed can be efficiently used in the design of suitable inductors.
      PubDate: 2014-05-10
       
  • Effective structural optimization based on equivalent static loads
           combined with system reduction method
    • Abstract: Abstract The present study proposes an efficient equivalent static load (ESL) method for dynamic optimization problems. The ESL method transforms dynamic problems into equivalent static problems. Although it provides an efficient way to solve dynamic optimization problems, large-scale dynamic problems still require heavy computation. In order to approximate solutions to dynamic optimization problems more efficiently, the proposed method combines ESLs with a system reduction method. The proposed method combines transient dynamic analysis with static optimization to form a highly efficient dynamic optimization algorithm.
      PubDate: 2014-05-09
       
  • Revisiting approximate reanalysis in topology optimization: on the
           advantages of recycled preconditioning in a minimum weight procedure
    • Abstract: Abstract An efficient procedure for three-dimensional continuum structural topology optimization is proposed. The approach is based on recycled preconditioning, where multigrid preconditioners are generated only at selected design cycles and re-used in subsequent cycles. Building upon knowledge regarding approximate reanalysis, it is shown that integrating recycled preconditioning into a minimum weight problem formulation can lead to a more efficient procedure than the common minimum compliance approach. Implemented in MATLAB, the run time is roughly twice faster than that of standard minimum compliance procedures. Computational savings are achieved without any compromise on the quality of the results in terms of the compliance-to-weight trade-off achieved. This provides a step towards integrating interactive 3-D topology optimization procedures into CAD software and mobile applications. MATLAB codes complementing the article can be downloaded from the author’s personal webpage.
      PubDate: 2014-05-09
       
 
 
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