As hyper-parameters are ubiquitous and can significantly affect the model performance, hyper-parameter optimization is extremely important in machine learning. In this paper, we consider a sub-class of hyper-parameter...
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ISBN:
(纸本)9781713899921
As hyper-parameters are ubiquitous and can significantly affect the model performance, hyper-parameter optimization is extremely important in machine learning. In this paper, we consider a sub-class of hyper-parameter optimization problems, where the hyper-gradients are not available. Such problems frequently appear when the performance metric is non-differentiable or the hyper-parameter is not continuous. However, existing algorithms, like Bayesian optimization and reinforcement learning, often get trapped in local optimals with poor performance. To address the above limitations, we propose to use cubic regularization to accelerate convergence and avoid saddle points. First, we adopt stochastic relaxation, which allows obtaining gradient and Hessian information without hyper-gradients. Then, we exploit the rich curvature information by cubic regularization. Theoretically, we prove that the proposed method can converge to approximate second-order stationary points, and the convergence is also guaranteed when the lower-level problem is inexactly solved. Experiments on synthetic and real-world data demonstrate the effectiveness of our proposed method.
To reduce the computational cost and time associated with automatic antenna optimization, this paper proposes a differential evolution algorithm with a variable population mechanism. Firstly, the paper introduces the ...
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This paper investigates the application of advanced metaheuristic algorithms Blood-Sucking Leech Optimizer (BSLO), Bonobo Optimizer (BO), and Electric Eel Foraging optimization (EEFO) to solve the optimal power flow (...
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This paper investigates the application of advanced metaheuristic algorithms Blood-Sucking Leech Optimizer (BSLO), Bonobo Optimizer (BO), and Electric Eel Foraging optimization (EEFO) to solve the optimal power flow (OPF) problem with stochastic renewable energy generators (REGs), specifically photovoltaic power generators (PVGs) and wind power generators (WGs). Two scenarios are examined: Scenario 1 evaluates the proposed algorithms performance without Flexible AC Transmission Systems (FACTS), focusing on minimizing Total Generation Cost (TGC), Active Power Loss (APL), and a combined objective of TGC and Emissions (TGCE). The TGC including both thermal and REG costs, in which the cost related to stochastic PV and wind power generation encompasses direct, reserve, and penalty costs due to overestimation and underestimation of available PV and wind power. Scenario 2 introduces the Thyristor-Controlled Series Capacitor (TCSC) and the Static Var Compensator (SVC) to evaluate their impact on three objective functions. The performance of the algorithms is evaluated on a modified IEEE 30-bus system. The results show that the BSLO algorithm consistently achieves the best TGC, APL, and TGCE values at 781.1209 $/h, 1.9960 MW, and 810.7376 $/h, respectively. These outcomes highlight its effectiveness and competitive performance in the first scenario. The integration of FACTS devices in the second scenario results in a 6.73% reduction in APL with the insertion of TCSC, a 1.86% reduction with the insertion of SVC, and a 6.10% reduction with the insertion of both TCSC and SVC, compared to the APL value in the case without FACTS devices (1.9960 MW). The study comprehensively analyzes how different optimization techniques and FACTS devices enhance power system performance with stochastic REG integration.
Network slicing is an essential technology in 5G and the forthcoming 6G networks. It aims to embed multiple virtual networks, i.e., network slices, on top of a shared substrate network to meet diverse service requirem...
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We provide a preliminary study on utilizing GPU (Graphics Processing Unit) to accelerate computation for three simulation optimization tasks with either first-order or second-order algorithms. Compared to the implemen...
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ISBN:
(纸本)9798331534202;9798331534219
We provide a preliminary study on utilizing GPU (Graphics Processing Unit) to accelerate computation for three simulation optimization tasks with either first-order or second-order algorithms. Compared to the implementation using only CPU (Central Processing Unit), the GPU implementation benefits from computational advantages of parallel processing for large-scale matrices and vectors operations. Numerical experiments demonstrate such computational advantages of utilizing GPU implementation in simulation optimization problems, and show that such advantage comparatively further increase as the problem scale increases.
The Artificial Electric Field Algorithm (AEFA) is categorized as one of the strong algorithms in the area of metaheuristics. It is influenced by Coulomb's law of the electrostatic force. Although it is known as an...
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In view of the different views of academia on the weight allocation of vulnerability assessment indicators, this study creatively proposed a data-based objective evaluation framework of water resource vulnerability, a...
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This letter presents a novel design for a transparent and flexible electromagnetic scatterer aimed at reducing radar cross section (RCS). Made from low-resistance indium tin oxide (ITO) thin film, PET, and PVC plastic...
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This letter presents a novel design for a transparent and flexible electromagnetic scatterer aimed at reducing radar cross section (RCS). Made from low-resistance indium tin oxide (ITO) thin film, PET, and PVC plastic, it achieves up to 81.3% transparency. The innovative unit design overcomes ITO's conductivity limitations and broadens bandwidth. Using the Pancharatnam-Berry phase principle, rotating the top-layer conductive structure creates encoded supercells. The letter explores RCS optimization using multiple algorithms, analyzes RCS changes in metasurface scatterer (MSS) with ITO patches in the conformal state, and compares the effects of ITO and copper on RCS performance. Multialgorithm optimization results in over 10 dB RCS reduction from 8.5 GHz to 19.8 GHz, even under 2 pi curvature or 45 degrees oblique incidence. With a compact size (0.135 lambda(0)), transparency(81.3%), flexibility(central angle up to 2 pi), and wideband performance (80%), the scatterer is ideal for applications like multispectral scattering, antenna radomes, and transparent windows.
Settlement modeling is essential because of the cohesive soil texture's intricacy. This study seeks to identify settlement (Sm) of shallow foundations using newly discovered ML approaches named the hybridized rand...
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Settlement modeling is essential because of the cohesive soil texture's intricacy. This study seeks to identify settlement (Sm) of shallow foundations using newly discovered ML approaches named the hybridized random forests analysis (RF) with grasshoppers optimization algorithm (GOA), the bat-inspired approach (BAT), beluga whale optimization (BWH). RF serves as the primary predictive model due to its robust ensemble learning approach. optimization algorithms enhance its predictive accuracy. Hybrid models (GOARF, BATRF, BWHRF) leverage the strengths of both RF and optimization algorithms to provide superior settlement predictions. By combining RF with these optimization techniques, the study aims to achieve highly accurate predictions of settlement for shallow foundations, demonstrating the effectiveness of these advanced machine-learning approaches. All the BATRF, GOARF, and BWHRF models accurately emulated the Sm, with R2 values of at least 0.985 for the training and 0.978 for the testing collection, respectively. Comparing the BWHRF to other models and literature, it is believed to be the appropriate system with the highest categorization. R2, RMSE, and MAE values during learning are 0.9913, 2.341, and 1.239 mm, respectively, which are superior by 0.9025, 8.09, and 4.92 mm over ANFIS-PSO. The values of the A_(15-index) index depict that the BWHRF can be outperformed by other models. Finally, after examining the validity and considering the assumptions, it is clear that the RF paired with BWH can perform more effectively than the BAT and GOA, and even ANFIS-PSO (literature), in the Sm simulation.
Railway traffic management requires a timely and accurate redefinition of routes and schedules in response to detected perturbations of the original timetable. To date, most of the (automated) solutions to this proble...
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Railway traffic management requires a timely and accurate redefinition of routes and schedules in response to detected perturbations of the original timetable. To date, most of the (automated) solutions to this problem require a central authority to make decisions for all the trains in a given control area. An appealing alternative is to consider trains as intelligent agents able to self -organize and determine the best traffic management strategy. This could lead to more scalable and resilient approaches, that can also take into account the real-time mobility demand. In this paper, we formalize the concept of railway traffic self -organization and we present an original design that enables its real -world deployment. We detail the principles at the basis of the sub -processes brought forth by the trains in a decentralized way, explaining their sequence and interaction. Moreover, we propose a preliminary proof of concept based on a realistic setting representing traffic in a French control area. The results allow conjecturing that self -organizing railway traffic management may be a viable option, and foster further research in this direction.
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