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...
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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.
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...
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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.
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...
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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,...
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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.
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...
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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.
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...
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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...
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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] .
Extrusion bioprinting is a popular biofabrication technique for creating viable biological constructs with applications ranging from regenerative medicine and cancer research to therapeutics screening. A primary chall...
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Extrusion bioprinting is a popular biofabrication technique for creating viable biological constructs with applications ranging from regenerative medicine and cancer research to therapeutics screening. A primary challenge within extrusion bioprinting lies in preserving cell viability and function amidst the shear forces generated during extrusion. Therefore, the formulation of shear-thinning bioinks with tailored flow properties is essential to minimize shear stress accumulation during printing. However, this task is complex, as the bioink's flow properties are contingent upon numerous factors, including but not limited to the polymer concentration, spatial cell density in the bioink, molecular weight of the polymer, and the nozzle's geometry. The current methods for adjusting flow properties are heuristic, posing challenges to the rapid development models and automation of the bioprinting workflow. In this study, we introduce a Gaussian Process-based multi-objective bayesian optimization framework that rapidly identifies Pareto-optimal flow property values to minimize hydrodynamic shear stresses during extrusion. The optimization focuses on four flow parameters, minimum viscosity, maximum viscosity, consistency index, and flow behavior index from the power-law model of shear-thinning fluids alongside the nozzle outlet diameter. Following an initial set of 24 experimental runs, our sequential design approach required 21 iterations to achieve convergence on a set of flow parameters that meet the Pareto optimality criteria. The presented strategy, which integrates physics-based numerical models with data-driven optimization models, emerges as a tool for the rapid fine-tuning of bioink flow behaviors. The multi-objective framework also sets the stage for future exploration into cell viability and functional outcomes post-bioprinting. (c) 2024 The Authors. Published by ELSEVIER Ltd. This is an open access article under the CC BY-NC-ND license (http://***
multi-objective bayesian optimization (MOBO) is broadly used for applications with high cost observations such as materials discovery. In BO, a derivative-free optimization algorithm is generally employed to maximize ...
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multi-objective bayesian optimization (MOBO) is broadly used for applications with high cost observations such as materials discovery. In BO, a derivative-free optimization algorithm is generally employed to maximize the acquisition function. In this study, we present a method for acquisition function maximization based on a (1 + 1)-evolutionary strategy in MOBO for materials discovery, which is a simple and easy-to-use approach with low computational complexity compared to conventional algorithms. In MOBO, weight vectors are used for scalarizing MO functions, typically employed to convert MO optimization into single-objectiveoptimization. The weight vectors at each round of MOBO are generally obtained using either stochastic (random sampling) or deterministic methods based on searched results. To clarify the effect of both the scalarizing methods on MOBO, we examine the effectiveness of random sampling methods versus two deterministic methods: reference-vector-based and self-organizing map-based decomposition methods. Experimental results from four test functions and a hydrogen storage material database as a concrete application show the effectiveness of the proposed method and the random sampling method. These results implied that the proposed method was useful for real-world MOBO experiments in materials discovery.
Aerospace product design optimizations, such as micro-aerial vehicle fuselage design, often involve multiple objectives. multi-objective bayesian optimization (MOBO) is an efficient approach in solving problems concer...
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Aerospace product design optimizations, such as micro-aerial vehicle fuselage design, often involve multiple objectives. multi-objective bayesian optimization (MOBO) is an efficient approach in solving problems concerning multiple conflicting objectives. Conventional MOBO approaches are often limited by sequential optimizations, which can only add one sample in each iteration. The parallel computing strategy is a desirable way to accelerate the optimization process by adding a batch of samples in one iteration. Unfortunately, existing parallel MOBO approaches are constrained to handling single-fidelity data, thereby missing out on the potential benefits of utilizing auxiliary low-fidelity data. To further improve the optimization efficiency of the parallel MOBO approach, this paper proposes two parallel MOBO approaches based on multi-fidelity surrogate modeling. Specially, the cheap auxiliary low-fidelity data can be utilized to improve the performance of the parallel MOBO approach by multi-fidelity surrogate modeling. The updating points and fidelity levels are determined by a modified hypervolume excepted improvement function, and two parallel computing strategies are developed for multi-point sampling. Additionally, a constraint handling strategy is developed for problems with constraints by adopting the probability of feasibility functions. The proposed approaches are demonstrated through numerical benchmark examples and two real-world applications involving the multi-objectiveoptimizations of a microaerial vehicle fuselage and a metamaterial vibration isolator. Results in the real-world applications show that the proposed approaches significantly improve the optimization efficiency with faster convergence speed and exhibit superior overall performance compared with the state-of-the-art MOBO methods.
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