The purpose of this study is to develop a robust control strategy based on the Sliding Mode Control (SMC) method and its advanced form of Double Integral Sliding Mode Control (DISMC) enhanced by a differential Evoluti...
详细信息
The purpose of this study is to develop a robust control strategy based on the Sliding Mode Control (SMC) method and its advanced form of Double Integral Sliding Mode Control (DISMC) enhanced by a differentialevolution (DE) algorithm. This approach focuses on offering a strong and effective method to adjust the controller parameters to minimize the tracking error between the PV output voltage and the reference. The DE algorithm uses initialization, mutation, crossover, and selection phases to accurately find the optimal controller coefficients for effectively implementing the control strategy of DISMC. The present paper highlights the superior performance of DE-DISMC compared to other controllers optimized with conventional methods, demonstrating its ability to provide the highest stability, accuracy, and efficiency to optimize the Maximum Power Point Tracking (MPPT) process. Using real climatic data from Errachidia city which is located in the south-east of Morocco, this work illustrates DE-DISMC's ability to maintain the PV system's peak performance in the face of varying environmental conditions, and the Lyapunov analysis confirms the system's stability. The results of this study are evaluated using various statistical and analytical metrics, including response time, magnitude of chattering, steady-state error, and efficiency. The findings highlight the high performance of the proposed DE-DISMC controller, especially under real climatic test conditions, achieving a response time of 1.1 ms, which is 58% faster than DE-ISMC and 89% than DE-CSMC, along with a negligible chattering magnitude of 2.8 x 10-6 V. It also demonstrates strong resilience and effectiveness, reaching a minimal steady-state error of 0.00014 V and a high efficiency of 99.99%. This balance makes DE-DISMC a reliable control solution, especially in changing environmental conditions.
Ultrasonic motors (USMs), characterized by their miniaturization, high precision, and low noise, are widely utilized in robotics, medical devices, and aerospace applications. However, existing torque control methods a...
详细信息
Ultrasonic motors (USMs), characterized by their miniaturization, high precision, and low noise, are widely utilized in robotics, medical devices, and aerospace applications. However, existing torque control methods are heavily dependent on sensors, which not only increase system cost and complexity but also restrict the deployment of USMs in space-constrained environments, thereby undermining their miniaturization advantages. Furthermore, the complex nonlinear torque characteristics and significant temperature effects of USMs have made traditional torque prediction methods based on physical models inadequate to meet the high-precision requirements of practical applications. To address these challenges, a real-time torque prediction method based on a hybrid attention mechanism, Hodrick-Prescott (HP) decomposition, and bidirectional long short-term memory (BiLSTM) network is proposed in this study. HP decomposition is employed to effectively capture both long-term trends and short-term fluctuations in time series data. The hybrid attention mechanism further highlights key input variables by distributing weights across time steps and feature dimensions. Finally, an improved differential evolution algorithm is applied to optimize the attention weights, enhancing model performance and reducing manual tuning effort. The proposed method's superiority is confirmed by experimental results, which demonstrate high prediction accuracy and rapid response under various operating conditions. These qualities make the method highly suitable for real-time, high-precision, and miniaturized applications such as small robotic joints driven by USMs and precise medical machines.
Traditional scheduling less account of human-related dynamic events: worker skill degradation and worker mandatory rest. However, in actual production, workers experience fatigue accumulation that decreases work effic...
详细信息
Traditional scheduling less account of human-related dynamic events: worker skill degradation and worker mandatory rest. However, in actual production, workers experience fatigue accumulation that decreases work efficiency, thereby decreasing the precision of jobs, increasing rework rates, and even elevating processing risks. It conflicts with the idea of industrial resilience and human well-being for Industry 5.0. Therefore, a humancentric dynamic distributed flexible job shop scheduling problem (HDDFJSP) has been researched in this paper. Firstly, a multi-objective mathematical model of HDDFJSP is proposed to minimize makespan, worker fatigue, and scheduling deviation. Secondly, a Q-learning improved differentialevolution (QLIDE) is designed to solve the HDDFJSP. In the QLIDE, a new four-layer encoding method and two initialization strategies are proposed to generate a high-quality initial population and a novel mutation strategy and two auxiliary mutation methods are designed to enhance the algorithm's exploitation capabilities. Furthermore, three neighborhood search strategies are introduced and combined with mutation operations as part of the Q-learning action phase to improve population convergence and diversity. Thirdly comparative test with four other well-known algorithms has been conducted and the results demonstrate the significant superiority of the QLIDE. Finally, the QLIDE is applied to solve a real case of a labor intensive hydraulic cylinder manufacturing enterprise. The results indicate that considering rescheduling can effectively help production managers to handle dynamic event of humans during the intelligent manufacturing systems.
The enhanced capabilities of autonomous underwater vehicles (AUVs) will facilitate sustainable exploration and utilization of maritime resources through improved precision in underwater mapping, resource extraction, a...
详细信息
The enhanced capabilities of autonomous underwater vehicles (AUVs) will facilitate sustainable exploration and utilization of maritime resources through improved precision in underwater mapping, resource extraction, and environmental surveillance. Enhanced navigation and communication systems will bolster the robustness and flexibility of AUVs, opening up new avenues for research and operations in demanding underwater conditions. The objective of this initiative is to optimize the performance of AUVs by developing sophisticated navigation methodologies specifically designed for complex marine environments. To achieve this goal, this paper proposes a modified structure of the well-known metaheuristic called differentialevolution (DE). The proposed algorithm is denoted by a fitness-based differential evolution algorithm (FDE). Through the utilization of path planning techniques and the application of the proposed FDE to enhance navigation, this paper seeks to overcome obstacles such as underwater barriers, restricted communication, and limited visibility. These enhancements are anticipated to notably elevate the efficacy and cognitive capabilities of AUVs. The validation of the proposed FDE algorithm is conducted on nine case studies of the path planning of AUV, and the comparison is made with other metaheuristic algorithms. The comparison indicates the effectiveness of the FDE in solving the AUV path planning problem.
Lot-streaming helps to achieve a more balanced utilization of parallel machines and more timely assembly of components, while component sharing increases the flexibility and commonality of assembly operations. Thus, t...
详细信息
Lot-streaming helps to achieve a more balanced utilization of parallel machines and more timely assembly of components, while component sharing increases the flexibility and commonality of assembly operations. Thus, this work addresses an assembly hybrid flowshop lot-streaming scheduling problem with component sharing. A mixed-integer linear programming model is formulated to scrutinize the coupling relations among variables i.e. sub-lot splitting, machine allocation, processing sequencing, and assembly sequencing, and to minimize the maximum completion time and work-in-process inventory lexicographically. To solve the above problem efficiently, a multi-strategy self-adaptive differentialevolution (MSDE) algorithm is developed. In MSDE, three problem-specific strategies that consider component integrity and specific requirements of production and assembly are integrated to enhance the initial population in terms of diversity and solution quality. A Q-learningbased selection mechanism is proposed to self-adaptively select an appropriate combination from mutation and crossover operators for achieving a balance between exploration and exploitation. An inventory reduction strategy is appended to largely reduce work-in-process components without extending completion time. Four conclusions are drawn from extensive experiments: (1) The ensemble of three population initialization strategies is superior to each individual one;(2) The Q-learning-based optimizer selection is more effective and robust than the single optimizer-based one;(3) The work-in-process inventory reduction strategy demonstrates remarkable effectiveness for most solutions;(4) MSDE outperforms the existing state-of-the-art algorithms in most cases.
This paper considers the optimization of investment strategies (ISs) for pension fund under market uncertainty. The target for this problem is to maximize the overall desired wealth (ODW) at the closed of the planning...
详细信息
This paper considers the optimization of investment strategies (ISs) for pension fund under market uncertainty. The target for this problem is to maximize the overall desired wealth (ODW) at the closed of the planning period while considering the risk of market uncertainty. To begin with, this problem is modeled as a discrete- time stochastic dynamic optimization problem (DTSDOP) with hard constraints (HCs) and uncertain constraints (UCs). Different from existing models, the main goal is to maximize ODW, rather than maximizing the wealth for individual investors, and to make sure that the pension fund is able to fulfill all obligations with a desired probability, this model introduces UCs instead of constraints on the variance. Additionally, this model takes into account the risk of market uncertainty, which helps to compare the optimal ISs with and without market uncertainty. Then, a deterministic transformation method is proposed for converting DTSDOP to a deterministic problem with HCs by fully utilizing the information of DTSDOP. Following that, a diversity dynamic adjustment and two-phase constraint handling strategy-based differential evolution algorithm (DDA-TPCHS-DEA) is proposed for attaining a global optimum for the discrete-time deterministic dynamic optimization problem (DTDDOP), in which constraints and the cost function are balanced by a diversity dynamic adjustment strategy, and a two-phase constraint handling strategy is utilized for finding the boundary knowledge for feasible and infeasible domains. Finally, the superiority of the proposed method is illustrated utilizing 21 test functions, an optimal design problem for robot grippers, and a pension fund investment problem under market uncertainty. The source code of the proposed method and its supplementary material are available in the following GitHub repository: https://***/xwu-gznu/DDA-TPRHS-DEA
Chest X-ray images play a crucial role in pneumonia diagnosis, with deep transfer learning being a widely adopted method for pneumonia detection. However, effectively handling feature data extracted from deep models w...
详细信息
Chest X-ray images play a crucial role in pneumonia diagnosis, with deep transfer learning being a widely adopted method for pneumonia detection. However, effectively handling feature data extracted from deep models without succumbing to the challenges of feature dimensionality remains a formidable task. In response to this complex issue, we propose a novel two-stage deep feature selection (FS) method utilizing the voting differentialevolution (VDE) algorithm. In this approach, a dimension adaptive search strategy is meticulously devised to ensure robust feature selection while concurrently reducing the dimension. To expedite the optimization process, we devise a CR adaptive adjustment method to enhance the efficiency of the algorithm. Notably, an important aspect of our approach is the introduction of a novel DE algorithm that integrates a voting mechanism. This synergistic fusion allows a comprehensive analysis of crucial feature relationships to mitigate the risk of algorithmic entrapment in local optima. Additionally, we propose a dynamic feature evaluation function to avert the oversight of feature sets with optimal classification accuracy during later stages of the algorithm, thereby preserving discriminative features. The method is verified on an open Chest X-Ray Images dataset, achieving 99.04% average precision, 98.67% average accuracy, 99.13% average recall, and 19.93% average feature dimension reduction ratio. The experimental findings reveal that the presented method outperform prevailing state-of-the-art algorithms.
Modern manufacturing heavily relies on mixed-model assembly lines to streamline production processes for various product configurations. However, most existing research in this area primarily focuses on deterministic ...
详细信息
Modern manufacturing heavily relies on mixed-model assembly lines to streamline production processes for various product configurations. However, most existing research in this area primarily focuses on deterministic demand scenarios, leaving the challenges posed by uncertain demand relatively unexplored. Such uncertainty can significantly impact assembly line efficiency, resource utilization, and throughput rates. This paper explores the complexities of balancing and sequencing in mixed-model assembly lines, particularly under conditions of uncertain demand. The proposed approach includes a robust mixed-integer linear programming model formulated to optimize production efficiency across diverse scenarios characterized by uncertain demand. To address this complex problem, a novel Q-Learning-Inspired differential evolution algorithm (QL-DE) has been developed. This algorithm utilizes a population-based evolutionary operator, an intra-population crossover operator, six task-centric and three product-centric neighborhood exploration operators, along with a Q-learning-inspired strategy. These components collectively enable the QL-DE algorithm to adaptively handle uncertain demand while optimizing assembly line processes. Finally, through a comparative analysis with five variants and five evolutionary algorithms, the QL-DE approach demonstrates its superior capability in efficiently addressing uncertain demand scenarios and optimizing the performance of mixed-model assembly lines.
This study presents a modified differential evolution algorithm for optimizing sandwich composite cylinders under hydrostatic pressure. The algorithm enforces balanced laminates using a while loop to enforce balanced ...
详细信息
This study presents a modified differential evolution algorithm for optimizing sandwich composite cylinders under hydrostatic pressure. The algorithm enforces balanced laminates using a while loop to enforce balanced laminates in both the initial population and trial vectors, reducing computational demands and accelerating convergence. Unlike previous studies, it demonstrates another novelty by including the number of plies and core thickness as design variables, alongside ply angles and layup sequences, enabling practical, customizable optimization. The approach increases failure load by 35.4% while reducing mass and demonstrates robustness by tolerating stochastic layup errors, resulting in resilient designs with enhanced performance.
External loads transferred from the structure's foundations to the soil induce stress increases in the soil stratum. Since stress increases within the soil mass vary with depth and across the plane at a given dept...
详细信息
External loads transferred from the structure's foundations to the soil induce stress increases in the soil stratum. Since stress increases within the soil mass vary with depth and across the plane at a given depth, approaches that estimate the average stress increase under foundations can be advantageous for effective foundation design. This study aims to develop optimization-based approximate methods for calculating average vertical stress increases with higher accuracy than the conventional 2V:1H method for rectangular foundations with different L/B ratios. For this purpose, vertical stress increases within the foundation projection at 120 different depths for 12 different L/B ratios were numerically calculated using Boussinesq's stress expressions. The model parameters of the proposed approximate models, such as expansion slopes (k or k1, k2) and normalized critical depth (zcr/B), for each L/B ratio were optimized using the differential evolution algorithm. The proposed three-parameter approximate method achieved the highest accuracy, reducing the RMSE values by an average of 53% compared to the conventional method, while the one-parameter model reduced the RMSE by 9%. The maximum absolute errors in the three-parameter model remained between 0.0217 and 0.0283, with R2 values greater than 0.9972. Building upon and improving the conventional method, this study presents a practical and novel three-parameter method that provides a more reliable and accurate estimation of the average vertical stress increase under flexible rectangular foundations, significantly reducing errors. This study contributes to geotechnical engineering by improving the accuracy of stress increase prediction models, potentially leading to more economical and safer foundation designs.
暂无评论