Piezoelectric fiber yarns produced by electrospinning offer a versatile platform for intelligent devices, demonstrating mechanical durability and the ability to convert mechanical strain into electric signals. While c...
详细信息
Piezoelectric fiber yarns produced by electrospinning offer a versatile platform for intelligent devices, demonstrating mechanical durability and the ability to convert mechanical strain into electric signals. While conventional methods involve twisting a single poly(vinylidene fluoride-co-trifluoroethylene)(P(VDF-TrFE)) fiber mat to create yarns, by limiting control over the mechanical properties, an approach inspired by composite laminate design principles is proposed for strengthening. By stacking multiple electrospun mats in various sequences and twisting them into yarns, the mechanical properties of P(VDF-TrFE) yarn structures are efficiently optimized. By leveraging a multi-objective bayesian optimization-based machine learning algorithm without imposing specific stacking restrictions, an optimal stacking sequence is determined that simultaneously enhances the ultimate tensile strength (UTS) and failure strain by considering the orientation angles of each aligned fiber mat as discrete design variables. The conditions on the Pareto front that achieve a balanced improvement in both the UTS and failure strain are identified. Additionally, applying corona poling induces extra dipole polarization in the yarn state, successfully fabricating mechanically robust and high-performance piezoelectric P(VDF-TrFE) yarns. Ultimately, the mechanically strengthened piezoelectric yarns demonstrate superior capabilities in self-powered sensing applications, particularly in challenging environments and sports scenarios, substantiating their potential for real-time signal detection.
Heterogeneous continuous flow hydrogenation is important in the chemical industry, yet the simultaneous optimization of yield and productivity has historically been complex. This study introduces a heterogeneous conti...
详细信息
Heterogeneous continuous flow hydrogenation is important in the chemical industry, yet the simultaneous optimization of yield and productivity has historically been complex. This study introduces a heterogeneous continuous flow hydrogenation system specifically designed for preparing 2-amino-3-methylbenzoic acid (AMA), employing FTIR inline analysis coupled with an artificial neural network model for monitoring. We explored two distinct reaction optimization strategies: multi-objective bayesian optimization (MOBO) and mechanism-based intrinsic kinetic modeling, executed in parallel to optimize reaction conditions. Remarkably, the MOBO approach achieved an optimal AMA yield (99%) and productivity (0.64 g/hour) within a limited number of iterations. In comparison, despite requiring extensive experimental data collection and equation fitting, the intrinsic kinetic modeling approach yielded a similar optimal result. Thus, while MOBO offers a more efficient route with fewer required experiments, kinetic modeling provides deeper insights into the optimization landscape but may be impacted by non-chemical kinetic phenomena and requires significant time and resources.
In the last years, there has been an increasing effort to develop bayesian methodologies to solve multi-objectiveoptimization problems. Most of these methods can be classified in two groups: infilling criterion-based...
详细信息
ISBN:
(纸本)9780791886236
In the last years, there has been an increasing effort to develop bayesian methodologies to solve multi-objectiveoptimization problems. Most of these methods can be classified in two groups: infilling criterion-based methods and aggregation-based methods. The first group employs an index that quantifies the gain that a new design can produce in the current Pareto front while the last group uses a (possibly non-linear) aggregation function and a weighting vector to identify a Pareto design. Most infilling-based methods have been developed to solve two-objectiveoptimization problems. Aggregation-based methods enable the solution of many-objectiveoptimization problems but their performance depends on the set of weighting vectors, which are often selected randomly. This study proposes a novel multi-objectivebayesian framework that exploits the rich probabilistic information that can be extracted from Gaussian process (GP) classifiers and the ability of conditional probabilities to capture design preferences. In the proposed framework, a GP classifier is trained to identify design zones that potentially contain Pareto designs. The training process involves the inference of a latent GP that encodes input-space interactions that describe a Pareto design. This latent GP enables the solution of many-objectiveoptimization problems with any standard acquisition function and without the prescription of a weighting vector. Conditional probabilities are utilized to define design goals that promote a uniform expansion of the Pareto front. The proposed approach is demonstrated with two benchmark analytical problems and the design optimization of sandwich composite armors for blast mitigation, which involves expensive finite element simulations.
This paper introduces a multi-objective bayesian optimization approach for concurrently optimizing the size and productivity of a steam methane reforming reactor. Seven design variables, resulting in a total of 3,929,...
详细信息
This paper introduces a multi-objective bayesian optimization approach for concurrently optimizing the size and productivity of a steam methane reforming reactor. Seven design variables, resulting in a total of 3,929,310 possible combinations, were explored, leading to three Pareto optimal designs after 100 iterations. Parametric studies were conducted first, and the results of bayesianoptimization were suggested with initial samples obtained via Latin Hypercube Sampling. The Pareto optimal designs revealed significant reduction in size and improvement in productivity. Furthermore, adjusting operating conditions, specifically the steam-to-carbon ratio, showed additional improvements of productivity. This study can contribute to efficiently proposing Pareto optimal designs with potential applications in hydrogen supply for compact and highly efficient systems.
Parallel infill sampling is a promising approach to improve the efficiency of multi-fidelity multi-objective bayesian optimization (MOBO). In existing literature, the number of infill samples per iteration is typicall...
详细信息
Parallel infill sampling is a promising approach to improve the efficiency of multi-fidelity multi-objective bayesian optimization (MOBO). In existing literature, the number of infill samples per iteration is typically limited to 10. Additionally, the application of the multi-fidelity MOBO method in engineering optimization designs with over 100 variables is rare. To that end, a novel generalized expected improvement matrix (GEIM) criterion is proposed by using generalized reference values for the element in expected improvement matrix. Parallel infill sampling strategy based on GEIM is developed and incorporated into the multi-fidelity MOBO framework. The distinct feature of the proposed method is that the number of infill samples at each iteration can be significantly larger than existing methods (i.e. as much as 100), so as to further enhance the optimization efficiency. Empirical experiment results on analytic problems show that the proposed parallel multi-fidelity MOBO method is highly competitive in comparison with existing methods. To address the curse of dimensionality in optimizing multi-stage axial compressor, an efficient modeling method for the Hierarchical Kriging (HK) is incorporated. The HK predictor for the efficiency of the 3-stage compressor with 144 variables is built in 16.71 s with acceptable accuracy. Remarkable improvements over the two objectives of the 3-stage compressor with 144 variables are achieved simultaneously within 870 high-fidelity CFD simulations.
Achieving accuracy with underresolved simulation of complex compressible flows with multiscale flow structures is a challenge. Either the numerical dissipation or the resolution and thereby the numerical cost is impra...
详细信息
Achieving accuracy with underresolved simulation of complex compressible flows with multiscale flow structures is a challenge. Either the numerical dissipation or the resolution and thereby the numerical cost is impractically high. Also, in the design of numerical solvers, the application of a solver for specific flow classes is balanced by robustness allowing the study of a broad range of flows. In this study, we propose a hybrid fifth -order targeted essentially non -oscillatory (TENO5)based scheme tailored to optimally simulate compressible flows with underresolved dilatational and vortical multiscale structures. For optimal design, three data -driven objectives are defined. A novel objective that derives from the numerical dissipation rate analysis is a key element to deal with underresolved complex flows in practical applications. The optimization process employs a multi -objectivebayesianoptimization framework with an expected hypervolume improvement and three flow configurations representative for a broad range of two- and three-dimensional flows with genuine and non -genuine subgrid scales. The optimized hybrid scheme is validated by comparing with shock -capturing schemes of the weighted essentially non -oscillatory (WENO)- and TENO- families with flows of complex shock interactions, Kelvin -Helmholtz instabilities, shockvortex interactions, vortical and turbulent flows
Many transportation system problems can be formulated as high-dimensional expensive multi-objective problems. They are challenging for Gaussian process-based bayesianoptimization methods to find the Pareto fronts due...
详细信息
Many transportation system problems can be formulated as high-dimensional expensive multi-objective problems. They are challenging for Gaussian process-based bayesianoptimization methods to find the Pareto fronts due to the curse of dimensionality and the boundary issue in the acquisition function optimization. This paper presents a multi-objective bayesian optimization method with block coordinate updates, Block-MOBO, to solve high-dimensional expensive multi-objective problems. Block-MOBO first partitions the decision variable space into different blocks, each of which includes a low-dimensional multi-objective problem. At each iteration, one block is considered and the decision variables not in this block are approximated by context-vector generation embedded with the Pareto prior knowl-edge thus promoting convergence. To tackle the boundary issue, we present ?-greedy acquisition function in a bayesian and multi-objective fashion, which recommends candidates either from the exploitation-exploration trade-off perspective or with probability ? from the Pareto dominance relationship perspective. We verify the effectiveness of Block-MOBO by comparing it with other multi-objectivebayesian methods on two real-world optimization problems in transportation system and three multi-objective synthetic test suites. The experimental results show that Block-MOBO can find more evenly distributed and non-dominated solutions in the whole search space with lower complexity compared with other state-of-the-art approaches. Our analyses illustrate that block coordinate updates and ?-greedy acquisition function contribute to computational complexity reduction and convergence-diversity trade-offs, respectively.
Animal diet design has been addressed mainly by optimizing analytical functions that describe digestible energy and essential nutrients, along with a set of restrictions regarding minimum nutritional content in the fe...
详细信息
Animal diet design has been addressed mainly by optimizing analytical functions that describe digestible energy and essential nutrients, along with a set of restrictions regarding minimum nutritional content in the feed formulation. This approach results in limitations since theoretical models are not flexible enough to incorporate variables related to environmental or zootechnical conditions that affect production efficiency or to include multiple objectives regarding current challenges associated with the adaptability to new environmental contexts and the reduction of ecological footprint. Unlike analytical methods, heuristic approaches can deal with variables from multiple sources using surrogate data-driven models of the objectives functions but commonly require thousands of evaluations of the target function, which is unfeasible in the context of animal diet formulation. This work proposes the use of bayesianoptimization as an alternative solution to address the animal diet design problem since it is intended to optimize costly-to-evaluate target functions and is able to deal with noisy sampling, which is helpful in handling the intrinsic variability in the nutrient content of raw materials. A multi-objective swine diet design problem is used to evaluate the suitability of bayesianoptimization to optimize three target functions: digestible energy, lysine, and cost, and the solutions are compared with a fractional stochastic programming approach. The analytical formulation of the problem is not considered by the bayesianoptimization approach, but target functions are modeled through surrogate bayesian models, where only input and output responses are used to drive the optimization process. Results show that a multi-objective bayesian optimization process is able to find better solutions than previously proposed methods, improving in 10.71%, 14.77%, and 3.79% the three objectives defined. Experiments using batches of query samples per iteration show that the o
One main challenge in multi-objective bayesian optimization of expensive problems is that only a very limited number of fitness evaluations can be afforded. To address the above challenge, this article introduces mult...
详细信息
One main challenge in multi-objective bayesian optimization of expensive problems is that only a very limited number of fitness evaluations can be afforded. To address the above challenge, this article introduces multisource online transfer learning into an evolutionary multi-objective bayesian optimization algorithm, facilitating the use of knowledge transferred from multiple computationally cheap problems. According to the dominance relationships of the solutions in the cheap and expensive problems, the source selection and style transfer mapping in online transfer learning are adopted to augment the data for training the Gaussian processes for the expensive problems, in which an adaptive online multisource transfer learning method is proposed based on the relationship between the balance factor parameter and the transfer mapping method. Comparative studies on two sets of widely used multi-objectiveoptimization benchmark problems, two sets of multi-task optimization problems, and one real-world expensive optimization problem confirm the effectiveness of the proposed algorithm.
Short carbon fiber-reinforced polymers (SCFRPs) are used in automotive and aerospace applications because of their superior strength-to-weight ratio and resistance to fatigue and thermal stresses. Fused filament fabri...
详细信息
Short carbon fiber-reinforced polymers (SCFRPs) are used in automotive and aerospace applications because of their superior strength-to-weight ratio and resistance to fatigue and thermal stresses. Fused filament fabrication (FFF) is considered an efficient fabrication method for SCFRP components, yet optimizing process parameters for specific performance targets is non-trivial and resource consuming. Herein, a multi-objective bayesian optimization (MOBO) framework for FFF-based SCFRP fabrication has been developed to fine-tune process parameters to optimize the trade-off between tensile strength and weight of the products. Initial random experiments were conducted on printed samples with different infill densities, printing speeds, and layer heights to evaluate their impact on specific tensile fracture energy (STFE) and component weight. These parameters were found to influence STFE and weight significantly. Data-driven sequential experimentation was then applied to identify a set of optimal values for these parameters. A surrogate-based optimization framework was utilized, and optimal points were determined through iterative refinement, with the process culminating when further iterations did not significantly enhance weight or STFE, indicating Pareto optimality. The efficacy of the methodology was demonstrated by identifying FFF parameters that achieve Pareto optimal STFE-to-weight ratios in nine iterations. This data-driven approach provides an efficient route to process optimization compared to heuristic and computational methods, streamlining the SCFRP design process via FFF and potentially extending to other composite systems and manufacturing processes. [GRAPHICS] .
暂无评论