Pub Date : 2025-10-24DOI: 10.1016/j.jestch.2025.102205
Ahmed Merze , Fatih Vehbi Çelebi
Optimizing toolpaths in 3D printing presents a significant challenge for achieving efficient and high-quality prints. In this study, a novel deep reinforcement learning (DRL) framework is proposed to overcome this problem. A core component of this framework is the proposed agent: Count-Prioritized Replay Deep Q-Network (CPR-DQN). The first key contribution is a developed simulation environment called PrintBoardEnv, which has curriculum learning built in. Secondly, a new method is developed for experience replay called Count-Prioritized Replay (CPR). The third key development is the CPR-DQN agent itself that uses a special architecture which includes features like Implicit Quantile Networks (IQN), Munchausen RL, Dueling, and Noisy Networks. Our agent is trained in two stages respectively, which is an offline pre-training, and then an online training. Our CPR-DQN agent is compared with other agents like DQN, Rainbow DQN, and Beyond The Rainbow (BTR). Furthermore, it is demonstrated that the CPR-DQN agent achieves great performance, highlighting the benefits of the proposed framework for toolpath optimization.
优化3D打印中的工具路径是实现高效和高质量打印的重大挑战。在本研究中，提出了一种新的深度强化学习（DRL）框架来克服这个问题。该框架的核心组件是提出的代理：计数优先重放深度q网络（CPR-DQN）。第一个关键贡献是开发了一个名为PrintBoardEnv的模拟环境，其中内置了课程学习。其次，提出了一种新的经验重播方法——计数优先重播（CPR）。第三个关键的发展是pr - dqn代理本身，它使用了一种特殊的架构，其中包括隐式分位数网络（IQN）、Munchausen强化学习、决斗和噪声网络等功能。我们的agent的训练分为两个阶段，一个是离线预训练，一个是在线训练。我们的CPR-DQN代理与DQN、Rainbow DQN和Beyond The Rainbow （BTR）等其他代理进行了比较。此外，还证明了CPR-DQN代理取得了良好的性能，突出了所提出的框架在刀具路径优化方面的优势。
{"title":"Advanced deep reinforcement learning for optimizing 3D printing toolpaths: A framework with enhanced agent architectures, Count-Prioritized Replay, and curriculum learning","authors":"Ahmed Merze , Fatih Vehbi Çelebi","doi":"10.1016/j.jestch.2025.102205","DOIUrl":"10.1016/j.jestch.2025.102205","url":null,"abstract":"<div><div>Optimizing toolpaths in 3D printing presents a significant challenge for achieving efficient and high-quality prints. In this study, a novel deep reinforcement learning (DRL) framework is proposed to overcome this problem. A core component of this framework is the proposed agent: Count-Prioritized Replay Deep Q-Network (CPR-DQN). The first key contribution is a developed simulation environment called <span>PrintBoardEnv</span>, which has curriculum learning built in. Secondly, a new method is developed for experience replay called Count-Prioritized Replay (CPR). The third key development is the CPR-DQN agent itself that uses a special architecture which includes features like Implicit Quantile Networks (IQN), Munchausen RL, Dueling, and Noisy Networks. Our agent is trained in two stages respectively, which is an offline pre-training, and then an online training. Our CPR-DQN agent is compared with other agents like DQN, Rainbow DQN, and Beyond The Rainbow (BTR). Furthermore, it is demonstrated that the CPR-DQN agent achieves great performance, highlighting the benefits of the proposed framework for toolpath optimization.</div></div>","PeriodicalId":48609,"journal":{"name":"Engineering Science and Technology-An International Journal-Jestech","volume":"72 ","pages":"Article 102205"},"PeriodicalIF":5.4,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145340870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-24DOI: 10.1016/j.jestch.2025.102214
Yuhang Duan , Jianfeng Wang , Shulin Lu , Lihong Cheng , Shuwen Huang , Kun Zhou , Yaobang Zhao , Junchen Li , Xiaohong Zhan
Controlling residual stress distribution during roll bending is essential for manufacturing high-precision components, such as rocket propellant tanks. However, the mechanisms governing stress evolution in this process remain insufficiently understood, which limits the development of effective control strategies. This study introduces a novel full-scale finite element model of a 4.7 m rocket tank panel, rigorously validated against experimental stress measurements, to reveal the governing mechanisms of residual stress development. Unlike prior studies limited to small-scale or simplified geometries, this work systematically clarifies the coupled influence of roller down displacement and roller spacing on stress evolution. Two novel optimization pathways are identified: (i) intermediate roller displacement (15–20 mm) reduces peak residual stress by 15–20 % through suppressing localized deformation; and (ii) optimal roller spacing (500–550 mm) enhances stress uniformity, reducing equivalent plastic strain by 30–40 %. Moreover, combined parameter optimization (17.5–20 mm displacement with 500–550 mm spacing) lowers critical zone stresses below 30 MPa, significantly improving dimensional stability. These findings not only establish the first validated full-scale stress evolution model for roll bending but also deliver practical, quantitative guidelines for stress control in large aerospace structures.
{"title":"Evolution mechanisms of residual stress in roll bending process for large-scale aerospace integral structures","authors":"Yuhang Duan , Jianfeng Wang , Shulin Lu , Lihong Cheng , Shuwen Huang , Kun Zhou , Yaobang Zhao , Junchen Li , Xiaohong Zhan","doi":"10.1016/j.jestch.2025.102214","DOIUrl":"10.1016/j.jestch.2025.102214","url":null,"abstract":"<div><div>Controlling residual stress distribution during roll bending is essential for manufacturing high-precision components, such as rocket propellant tanks. However, the mechanisms governing stress evolution in this process remain insufficiently understood, which limits the development of effective control strategies. This study introduces a novel full-scale finite element model of a 4.7 m rocket tank panel, rigorously validated against experimental stress measurements, to reveal the governing mechanisms of residual stress development. Unlike prior studies limited to small-scale or simplified geometries, this work systematically clarifies the coupled influence of roller down displacement and roller spacing on stress evolution. Two novel optimization pathways are identified: (i) intermediate roller displacement (15–20 mm) reduces peak residual stress by 15–20 % through suppressing localized deformation; and (ii) optimal roller spacing (500–550 mm) enhances stress uniformity, reducing equivalent plastic strain by 30–40 %. Moreover, combined parameter optimization (17.5–20 mm displacement with 500–550 mm spacing) lowers critical zone stresses below 30 MPa, significantly improving dimensional stability. These findings not only establish the first validated full-scale stress evolution model for roll bending but also deliver practical, quantitative guidelines for stress control in large aerospace structures.</div></div>","PeriodicalId":48609,"journal":{"name":"Engineering Science and Technology-An International Journal-Jestech","volume":"72 ","pages":"Article 102214"},"PeriodicalIF":5.4,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145365267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-15DOI: 10.1016/j.jestch.2025.102186
Seshagiri Rao Sugguna, Sumesh E.P
Magnetic Resonance Imaging (MRI) is widely used for brain disease diagnosis due to its superior tissue contrast, but low-field MRI scanners often generate low-resolution images that hinder accurate interpretation. Extending scan time or upgrading to high-field systems increases cost and patient discomfort, making them impractical solutions. Deep learning-based super-resolution has emerged as a promising alternative; however, conventional CNN and GAN-based models frequently oversmooth details, introduce artifacts, or rely on synthetic downsampling, thereby limiting their clinical reliability. To address these challenges, we propose HybridNet, a novel CNN-based framework that integrates even–odd pixel decomposition with Dense Attention Blocks (DABs) to capture both global structural consistency and fine anatomical details. The novelty of HybridNet lies in its dual-focus strategy pixel decomposition to preserve structural integrity and reduce aliasing, and dense attention integration to highlight diagnostically significant regions, resulting in sharper and more reliable MRI reconstructions. The objectives of this study includes — design a clinically reliable MRI super-resolution framework that minimizes artifacts and oversmoothing, to ensure generalization across different scanners and acquisition settings, and to provide perceptually faithful reconstructions that aid radiological interpretation without increasing scan time or hardware cost. Proposed HybridNet model is trained on real paired MRI datasets from different scanners, The result demonstrates strong robustness and diagnostic relevance in both Quantitative and qualitative aspects. Quantitative evaluations reveal an improvement of 6–15 dB in PSNR and 2%–4% in SSIM compared to state-of-the-art methods such as SRCNN, FSRCNN, VDSR, and EDSR. Ablation studies further confirm the role of pixel decomposition, attention integration, and feature fusion in enhancing performance. Radiologists’ subjective assessments also validate superior perceptual quality, achieving a Mean Opinion Score of 87.3 and a Perceptual Evaluation score of 73.35. Overall, HybridNet offers a cost-effective and clinically practical solution for enhancing MRI image quality.
{"title":"HybridNet: Advancing MRI image quality using dense attention and deep learning","authors":"Seshagiri Rao Sugguna, Sumesh E.P","doi":"10.1016/j.jestch.2025.102186","DOIUrl":"10.1016/j.jestch.2025.102186","url":null,"abstract":"<div><div>Magnetic Resonance Imaging (MRI) is widely used for brain disease diagnosis due to its superior tissue contrast, but low-field MRI scanners often generate low-resolution images that hinder accurate interpretation. Extending scan time or upgrading to high-field systems increases cost and patient discomfort, making them impractical solutions. Deep learning-based super-resolution has emerged as a promising alternative; however, conventional CNN and GAN-based models frequently oversmooth details, introduce artifacts, or rely on synthetic downsampling, thereby limiting their clinical reliability. To address these challenges, we propose HybridNet, a novel CNN-based framework that integrates even–odd pixel decomposition with Dense Attention Blocks (DABs) to capture both global structural consistency and fine anatomical details. The novelty of HybridNet lies in its dual-focus strategy pixel decomposition to preserve structural integrity and reduce aliasing, and dense attention integration to highlight diagnostically significant regions, resulting in sharper and more reliable MRI reconstructions. The objectives of this study includes — design a clinically reliable MRI super-resolution framework that minimizes artifacts and oversmoothing, to ensure generalization across different scanners and acquisition settings, and to provide perceptually faithful reconstructions that aid radiological interpretation without increasing scan time or hardware cost. Proposed HybridNet model is trained on real paired MRI datasets from different scanners, The result demonstrates strong robustness and diagnostic relevance in both Quantitative and qualitative aspects. Quantitative evaluations reveal an improvement of 6–15 dB in PSNR and 2%–4% in SSIM compared to state-of-the-art methods such as SRCNN, FSRCNN, VDSR, and EDSR. Ablation studies further confirm the role of pixel decomposition, attention integration, and feature fusion in enhancing performance. Radiologists’ subjective assessments also validate superior perceptual quality, achieving a Mean Opinion Score of 87.3 and a Perceptual Evaluation score of 73.35. Overall, HybridNet offers a cost-effective and clinically practical solution for enhancing MRI image quality.</div></div>","PeriodicalId":48609,"journal":{"name":"Engineering Science and Technology-An International Journal-Jestech","volume":"71 ","pages":"Article 102186"},"PeriodicalIF":5.4,"publicationDate":"2025-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145320841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-14DOI: 10.1016/j.jestch.2025.102204
Sinan Suli , Yasemin Öner , İbrahim Şenol
This study presents a design methodology for synchronous reluctance (SynRM) and permanent magnet-assisted synchronous reluctance motors (PMaSynRM), developed through rotor lamination optimizations without altering the existing stator platform. This approach enables the realization of different motor types using a common stator, eliminating the need for additional tooling costs in the production line. It is based on the principle of “Efficiency Class Upgrade with Minimum Die Cost”, whereby the existing tooling infrastructure is preserved, and higher-efficiency motors are prototyped at low cost through topological modifications in the rotor design.
Using a multi-objective genetic algorithm (MOGA), rotor designs were optimized to achieve Pareto-optimal solutions among conflicting targets such as torque production, efficiency, magnet volume, and torque ripple. The electromagnetic performance of rotor geometries was assessed via 2D finite element analysis (FEA), providing flux distribution, torque profiles, and efficiency curves.
A reference IE2-class induction motor (IM) was used as the baseline, upon which SynRM and PMaSynRM models were designed using the same stator. These three motor types were comparatively analyzed, along with a dimensional-level comparison against the IE4 version of the same motor. Throughout the process, the stator geometry, slot structure, and winding features remained unchanged, ensuring design novelty through rotor-side innovations.
The results demonstrate the electromagnetic potential and structural compatibility of SynRM and PMaSynRM configurations with the existing stator. The proposed method offers a scalable and cost-effective solution for manufacturers aiming to adopt high-efficiency motor technologies, paving a transition path from industrial motors to electric vehicle (EV) applications via a unified stator platform.
This study is limited to an IE2-class, frame-90, four-pole squirrel-cage IM stator reference; applying the methodology to other frame sizes and pole counts requires re-parameterization. From a practical standpoint, redesigning only the rotor eliminates stator/winding tooling costs, enabling efficiency-class upgrades and making the approach suitable for rapid industrial adoption. From a social perspective, higher efficiency and reduced dependence on rare-earth materials contribute to energy savings and supply-chain sustainability.
{"title":"Design of SynRM and PMaSynRM using a common industrial stator platform: a new design methodology for transition from industrial applications to electric vehicles","authors":"Sinan Suli , Yasemin Öner , İbrahim Şenol","doi":"10.1016/j.jestch.2025.102204","DOIUrl":"10.1016/j.jestch.2025.102204","url":null,"abstract":"<div><div>This study presents a design methodology for synchronous reluctance (SynRM) and permanent magnet-assisted synchronous reluctance motors (PMaSynRM), developed through rotor lamination optimizations without altering the existing stator platform. This approach enables the realization of different motor types using a common stator, eliminating the need for additional tooling costs in the production line. It is based on the principle of “Efficiency Class Upgrade with Minimum Die Cost”, whereby the existing tooling infrastructure is preserved, and higher-efficiency motors are prototyped at low cost through topological modifications in the rotor design.</div><div>Using a multi-objective genetic algorithm (MOGA), rotor designs were optimized to achieve Pareto-optimal solutions among conflicting targets such as torque production, efficiency, magnet volume, and torque ripple. The electromagnetic performance of rotor geometries was assessed via 2D finite element analysis (FEA), providing flux distribution, torque profiles, and efficiency curves.</div><div>A reference IE2-class induction motor (IM) was used as the baseline, upon which SynRM and PMaSynRM models were designed using the same stator. These three motor types were comparatively analyzed, along with a dimensional-level comparison against the IE4 version of the same motor. Throughout the process, the stator geometry, slot structure, and winding features remained unchanged, ensuring design novelty through rotor-side innovations.</div><div>The results demonstrate the electromagnetic potential and structural compatibility of SynRM and PMaSynRM configurations with the existing stator. The proposed method offers a scalable and cost-effective solution for manufacturers aiming to adopt high-efficiency motor technologies, paving a transition path from industrial motors to electric vehicle (EV) applications via a unified stator platform.</div><div>This study is limited to an IE2-class, frame-90, four-pole squirrel-cage IM stator reference; applying the methodology to other frame sizes and pole counts requires re-parameterization. From a practical standpoint, redesigning only the rotor eliminates stator/winding tooling costs, enabling efficiency-class upgrades and making the approach suitable for rapid industrial adoption. From a social perspective, higher efficiency and reduced dependence on rare-earth materials contribute to energy savings and supply-chain sustainability.</div></div>","PeriodicalId":48609,"journal":{"name":"Engineering Science and Technology-An International Journal-Jestech","volume":"71 ","pages":"Article 102204"},"PeriodicalIF":5.4,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-14DOI: 10.1016/j.jestch.2025.102207
Shitao Lv , Dongchen Sui , Qiner Xu , Yi Cao , Qiang Xu , Haiyan Sun , Tengfei Xu , Jicong Zhao
Laterally excited bulk acoustic resonator (XBAR) exhibits a high electromechanical coupling coefficient (kt2) due to their intrinsically superior piezoelectric properties, which is highly advantageous for the subsequent design and implementation of acoustic filters. However,it is not yet suitable for commercial application due to its numerous spurious modes and low quality factor (Q value). This paper presents an exhaustive analysis of the origins of in-band spurious modes and the method to suppress based on the first-order antisymmetric (A1) mode XBAR. Simulation results indicate that these spurious modes primarily originate from acoustic wave scattering along unintended propagation paths and standing waves caused by crosstalk between electrodes. These spurious modes lead to energy dissipation, thereby reducing the resonator’s Q value. To effectively suppress them without increasing fabrication complexity while significantly enhancing the Q value, an etching-hole strategy is proposed, introducing the transverse holes that create acoustic impedance mismatch based on velocity differences. Additionally, the adoption of a half electrode configuration optimizes the electric field and stress redistribution within the resonator, thereby effectively reducing interfacial losses at the electrode-piezoelectric layer interface and enhancing the Q value by approximately 3.5 times. The fabricated XBAR, integrating holes and half electrode configuration, exhibits an in-band spurious-free response, a Bode-Q value of 1954, a kt2 of 27.5 % and an exceptionally high figure of merit (FOM = kt2 × Bode-Q) of 537.
{"title":"In-band spurious suppression in first-order antisymmetric-mode resonators using air holes and half electrode","authors":"Shitao Lv , Dongchen Sui , Qiner Xu , Yi Cao , Qiang Xu , Haiyan Sun , Tengfei Xu , Jicong Zhao","doi":"10.1016/j.jestch.2025.102207","DOIUrl":"10.1016/j.jestch.2025.102207","url":null,"abstract":"<div><div>Laterally excited bulk acoustic resonator (XBAR) exhibits a high electromechanical coupling coefficient (<em>k<sub>t</sub></em><sup>2</sup>) due to their intrinsically superior piezoelectric properties, which is highly advantageous for the subsequent design and implementation of acoustic filters. However,it is not yet suitable for commercial application due to its numerous spurious modes and low quality factor (<em>Q</em> value). This paper presents an exhaustive analysis of the origins of in-band spurious modes and the method to suppress based on the first-order antisymmetric (A1) mode XBAR. Simulation results indicate that these spurious modes primarily originate from acoustic wave scattering along unintended propagation paths and standing waves caused by crosstalk between electrodes. These spurious modes lead to energy dissipation, thereby reducing the resonator’s <em>Q</em> value. To effectively suppress them without increasing fabrication complexity while significantly enhancing the <em>Q</em> value, an etching-hole strategy is proposed, introducing the transverse holes that create acoustic impedance mismatch based on velocity differences. Additionally, the adoption of a half electrode configuration optimizes the electric field and stress redistribution within the resonator, thereby effectively reducing interfacial losses at the electrode-piezoelectric layer interface and enhancing the <em>Q</em> value by approximately 3.5 times. The fabricated XBAR, integrating holes and half electrode configuration, exhibits an in-band spurious-free response, a Bode-<em>Q</em> value of 1954, a <em>k<sub>t</sub></em><sup>2</sup> of 27.5 % and an exceptionally high figure of merit (<em>FOM</em> = <em>k<sub>t</sub></em><sup>2</sup> × Bode-<em>Q</em>) of 537.</div></div>","PeriodicalId":48609,"journal":{"name":"Engineering Science and Technology-An International Journal-Jestech","volume":"71 ","pages":"Article 102207"},"PeriodicalIF":5.4,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-09DOI: 10.1016/j.jestch.2025.102200
Md. Ismail Hossen , Saif Hannan , Mohammad Tariqul Islam , Abdulmajeed M. Alenezi , Mohamed S. Soliman
Electromagnetic (EM) wave shielding in modern wireless systems encounters critical challenges, including polarization insensitivity, broadband operation, and compact design requirements. This work introduces a rotationally symmetric metamaterial absorber featuring emblem-shaped continuous transmission line resonators, specifically engineered to achieve high-efficiency absorption across the C, X, and Ku bands. The proposed design demonstrates remarkable absorption rates of 96.77 %, 99.68 %, 99.68 %, 99.70 %, 98.03 %, 99.68 %, and 99.98 % at resonance frequencies of 5.834 GHz, 7.192 GHz, 7.766 GHz, 10.65 GHz, 14.038 GHz, 15.34 GHz, and 15.62 GHz, respectively. Benefiting from rotational symmetry, the absorber maintains complete insensitivity to both co- and cross-polarized incident waves, with stable performance under oblique angles up to 90°. A maximum shielding effectiveness of 78 dB is achieved at the targeted frequencies, ensuring robust protection against EM interference. The compact unit cell (0.233λ × 0.233λ) exhibits near-zero permittivity, permeability, and refractive index with single-negative properties, further supporting efficient absorption within a minimal footprint. To validate the physical behavior, an equivalent RLC circuit model was developed in ADS, showing excellent agreement with CST simulations. Experimental verification using fabricated prototypes and Vector Network Analyzer measurements confirms the strong consistency between simulated and measured results. The novelty of this work lies in the integration of an emblem-shaped resonator with a continuous transmission line in a rotationally symmetric layout, enabling broadband absorption, polarization, and angle insensitivity, as well as high shielding effectiveness within a compact geometry. These features make the proposed absorber highly suitable for Wi-Fi, 5G, aerospace, defense radar, and stealth EM shielding applications.
{"title":"Rotational symmetric metamaterial structure of emblemed number connected with continuous transmission line for EM wave shielding applications","authors":"Md. Ismail Hossen , Saif Hannan , Mohammad Tariqul Islam , Abdulmajeed M. Alenezi , Mohamed S. Soliman","doi":"10.1016/j.jestch.2025.102200","DOIUrl":"10.1016/j.jestch.2025.102200","url":null,"abstract":"<div><div>Electromagnetic (EM) wave shielding in modern wireless systems encounters critical challenges, including polarization insensitivity, broadband operation, and compact design requirements. This work introduces a rotationally symmetric metamaterial absorber featuring emblem-shaped continuous transmission line resonators, specifically engineered to achieve high-efficiency absorption across the C, X, and Ku bands. The proposed design demonstrates remarkable absorption rates of 96.77 %, 99.68 %, 99.68 %, 99.70 %, 98.03 %, 99.68 %, and 99.98 % at resonance frequencies of 5.834 GHz, 7.192 GHz, 7.766 GHz, 10.65 GHz, 14.038 GHz, 15.34 GHz, and 15.62 GHz, respectively. Benefiting from rotational symmetry, the absorber maintains complete insensitivity to both co- and cross-polarized incident waves, with stable performance under oblique angles up to 90°. A maximum shielding effectiveness of 78 dB is achieved at the targeted frequencies, ensuring robust protection against EM interference. The compact unit cell (0.233λ × 0.233λ) exhibits near-zero permittivity, permeability, and refractive index with single-negative properties, further supporting efficient absorption within a minimal footprint. To validate the physical behavior, an equivalent RLC circuit model was developed in ADS, showing excellent agreement with CST simulations. Experimental verification using fabricated prototypes and Vector Network Analyzer measurements confirms the strong consistency between simulated and measured results. The novelty of this work lies in the integration of an emblem-shaped resonator with a continuous transmission line in a rotationally symmetric layout, enabling broadband absorption, polarization, and angle insensitivity, as well as high shielding effectiveness within a compact geometry. These features make the proposed absorber highly suitable for Wi-Fi, 5G, aerospace, defense radar, and stealth EM shielding applications.</div></div>","PeriodicalId":48609,"journal":{"name":"Engineering Science and Technology-An International Journal-Jestech","volume":"71 ","pages":"Article 102200"},"PeriodicalIF":5.4,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-04DOI: 10.1016/j.jestch.2025.102203
Najmul Alam, M.A. Rahman, Md. Arafat Hossain, Md. Rashidul Islam
Forecasting the charging demand of electric vehicle charging stations (EVCSs) is critical for urban planning, resource allocation, policy development, and efficient grid management. However, reliance on sensor-collected data transmitted through various communication channels poses significant cybersecurity risks to forecasting models. This study evaluates the vulnerability of several commonly used forecasting models named random forest (RF), convolutional neural network (CNN), convolutional long short-term memory (ConvLSTM), and bidirectional convolutional long short-term memory (BiConvLSTM), under simulated cyber-attacks. Different attack scenarios, including fast gradient sign method (FGSM) and basic iterative method (BIM)-based adversarial attacks and scaling-based false data injection (FDI) attacks, are considered with varying attack volumes and perturbations. Metrics, such as root mean square error (RMSE), mean absolute error (MAE), and mean absolute percentage error (MAPE), are employed to assess and compare the accuracies of different models. Results indicate that forecasting models exhibit significant performance degradation under these cyber-attacks. As a countermeasure, adversarial training has been employed to mitigate the impact of such attacks and has proven to be highly effective. The experimental observations in this research elucidate the impact of cyber-attacks along with a defense mechanism to mitigate economic and technical risks to the EVCS, fostering the future development of accurate and cyber-resilient forecasting methodologies essential for advancing both academic and industrial domains of EVCS demand forecasting.
{"title":"Secure electric vehicle charging station demand forecasting under adversarial and false data injection attacks","authors":"Najmul Alam, M.A. Rahman, Md. Arafat Hossain, Md. Rashidul Islam","doi":"10.1016/j.jestch.2025.102203","DOIUrl":"10.1016/j.jestch.2025.102203","url":null,"abstract":"<div><div>Forecasting the charging demand of electric vehicle charging stations (EVCSs) is critical for urban planning, resource allocation, policy development, and efficient grid management. However, reliance on sensor-collected data transmitted through various communication channels poses significant cybersecurity risks to forecasting models. This study evaluates the vulnerability of several commonly used forecasting models named random forest (RF), convolutional neural network (CNN), convolutional long short-term memory (ConvLSTM), and bidirectional convolutional long short-term memory (BiConvLSTM), under simulated cyber-attacks. Different attack scenarios, including fast gradient sign method (FGSM) and basic iterative method (BIM)-based adversarial attacks and scaling-based false data injection (FDI) attacks, are considered with varying attack volumes and perturbations. Metrics, such as root mean square error (RMSE), mean absolute error (MAE), and mean absolute percentage error (MAPE), are employed to assess and compare the accuracies of different models. Results indicate that forecasting models exhibit significant performance degradation under these cyber-attacks. As a countermeasure, adversarial training has been employed to mitigate the impact of such attacks and has proven to be highly effective. The experimental observations in this research elucidate the impact of cyber-attacks along with a defense mechanism to mitigate economic and technical risks to the EVCS, fostering the future development of accurate and cyber-resilient forecasting methodologies essential for advancing both academic and industrial domains of EVCS demand forecasting.</div></div>","PeriodicalId":48609,"journal":{"name":"Engineering Science and Technology-An International Journal-Jestech","volume":"71 ","pages":"Article 102203"},"PeriodicalIF":5.4,"publicationDate":"2025-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-01DOI: 10.1016/j.jestch.2025.102201
Onur Hamza Karabey
This paper presents the design and analysis of a continuously linear polarization-agile antenna based on Microwave Liquid Crystal (LC) technology. The proposed concept is specifically developed for Ku-band (e.g. 12 GHz) satellite communication applications, where systems typically operate with linear polarization and maintaining polarization alignment, referred to as skew angle adjustment, is critical for reliable on-the-move operation and for avoiding link loss. The antenna system incorporates a tunable feed network comprising two directional couplers and LC-based continuously tunable phase shifters. These feed a dual-fed microstrip patch antenna, enabling full-range linear polarization control over by electronically adjusting the differential phase. The proposed tunable feed network is implemented using microwave LC technology to enable a fully passive architecture without requiring low-noise amplifiers. LC materials offer electrically tunable dielectric properties with inherently low dielectric loss, typically below 0.06 at frequencies beyond 10 GHz, and their loss tangent decreases with increasing frequency, making them particularly well-suited for Ku-band applications and beyond. In addition, LC materials benefit from a mature fabrication infrastructure originating from LC display manufacturing, allowing low-cost, large-area, and scalable production. Full-wave simulations at 12 GHz show that the system achieves a cross-polarization discrimination (XPD) better than 25 dB across the entire skew angle range. The LC-based phase shifters operate with only two bias voltages and provide 180° differential phase shift with an insertion loss below 2.3 dB, yielding a figure-of-merit of 80°/dB at 12 GHz. These results demonstrate the feasibility of the proposed design for low-loss, scalable, and reconfigurable antenna arrays in Ku-band and beyond satellite systems.
{"title":"Design and analysis of a continuously linear polarization agile antenna using microwave liquid crystal technology","authors":"Onur Hamza Karabey","doi":"10.1016/j.jestch.2025.102201","DOIUrl":"10.1016/j.jestch.2025.102201","url":null,"abstract":"<div><div>This paper presents the design and analysis of a continuously linear polarization-agile antenna based on Microwave Liquid Crystal (LC) technology. The proposed concept is specifically developed for Ku-band (e.g. 12 GHz) satellite communication applications, where systems typically operate with linear polarization and maintaining polarization alignment, referred to as skew angle adjustment, is critical for reliable on-the-move operation and for avoiding link loss. The antenna system incorporates a tunable feed network comprising two directional couplers and LC-based continuously tunable phase shifters. These feed a dual-fed microstrip patch antenna, enabling full-range linear polarization control over <span><math><mrow><mo>±</mo><mn>18</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>∘</mo></mrow></msup></mrow></math></span> by electronically adjusting the differential phase. The proposed tunable feed network is implemented using microwave LC technology to enable a fully passive architecture without requiring low-noise amplifiers. LC materials offer electrically tunable dielectric properties with inherently low dielectric loss, typically below 0.06 at frequencies beyond 10 GHz, and their loss tangent decreases with increasing frequency, making them particularly well-suited for Ku-band applications and beyond. In addition, LC materials benefit from a mature fabrication infrastructure originating from LC display manufacturing, allowing low-cost, large-area, and scalable production. Full-wave simulations at 12 GHz show that the system achieves a cross-polarization discrimination (XPD) better than 25 dB across the entire skew angle range. The LC-based phase shifters operate with only two bias voltages and provide 180° differential phase shift with an insertion loss below 2.3 dB, yielding a figure-of-merit of 80°/dB at 12 GHz. These results demonstrate the feasibility of the proposed design for low-loss, scalable, and reconfigurable antenna arrays in Ku-band and beyond satellite systems.</div></div>","PeriodicalId":48609,"journal":{"name":"Engineering Science and Technology-An International Journal-Jestech","volume":"71 ","pages":"Article 102201"},"PeriodicalIF":5.4,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-26DOI: 10.1016/j.jestch.2025.102198
Azita Laily Yusof, Ahmad Zaki Aiman Abdul Rashid, Darmawaty Mohd Ali
Within the last ten years, UAVs has captured both the academia’s and industry players attention due to their capabilities to be utilized in multiple applications. One of the most prominent functionalities that UAVs provided for multiple applications is communication. Due to these functionalities, UAVs are seen as a major player in the 5G/6G cellular networks. Extending the connectivity and communication through multiple devices is the main goal of the 5G/6G networks. In this context, UAVs can either be deployed as relays that receive signals from BS and transmit them to the UE, or the UAVs can be utilized as a BS that flies (UAV-BS) and supplies 5G/6G communication to the UEs on the ground. However, there are many issues that arise with UAV communication networks when trying to provide signal coverage to users. One of the issues is when utilizing UAV as a BS, the signal coverage’s quality might not be up to par due to the UAV’s high mobility characteristics, which also leads to the frequent handover experienced by the users on the ground. Frequent handovers, or “ping-pong” handovers, are not acceptable and can instigate other problems that reduce the quality of the signal, such as packet delays, or losses of packets. Efficient handover management in drone communication is the solution to this problem, and, thus, it requires to be applied to the UAV networks to sustain connectivity that is reliable and stable. This paper studies the handover management for UAV communication in 5G networks using the systematic literature review (SLR) technique for its methodology. Multiple topics related to the handover scenario in the UAV networks are being highlighted in this paper, alongside studies related to machine learning (ML) usage in making handover decisions. A total of 90 research papers that relate to the handover in UAV networks and that were published from 2019 to 2024 were chosen. The results from our studies show that machine learning is able to provide handover decision that are more efficient and robust than traditional/conventional methods of making handover decisions. Finally, several discussions based on several themes and the limitations of the studies were held.
{"title":"Handover management for UAV communication in 5G networks: A systematic literature review","authors":"Azita Laily Yusof, Ahmad Zaki Aiman Abdul Rashid, Darmawaty Mohd Ali","doi":"10.1016/j.jestch.2025.102198","DOIUrl":"10.1016/j.jestch.2025.102198","url":null,"abstract":"<div><div>Within the last ten years, UAVs has captured both the academia’s and industry players attention due to their capabilities to be utilized in multiple applications. One of the most prominent functionalities that UAVs provided for multiple applications is communication. Due to these functionalities, UAVs are seen as a major player in the 5G/6G cellular networks. Extending the connectivity and communication through multiple devices is the main goal of the 5G/6G networks. In this context, UAVs can either be deployed as relays that receive signals from BS and transmit them to the UE, or the UAVs can be utilized as a BS that flies (UAV-BS) and supplies 5G/6G communication to the UEs on the ground. However, there are many issues that arise with UAV communication networks when trying to provide signal coverage to users. One of the issues is when utilizing UAV as a BS, the signal coverage’s quality might not be up to par due to the UAV’s high mobility characteristics, which also leads to the frequent handover experienced by the users on the ground. Frequent handovers, or “ping-pong” handovers, are not acceptable and can instigate other problems that reduce the quality of the signal, such as packet delays, or losses of packets. Efficient handover management in drone communication is the solution to this problem, and, thus, it requires to be applied to the UAV networks to sustain connectivity that is reliable and stable. This paper studies the handover management for UAV communication in 5G networks using the systematic literature review (SLR) technique for its methodology. Multiple topics related to the handover scenario in the UAV networks are being highlighted in this paper, alongside studies related to machine learning (ML) usage in making handover decisions. A total of 90 research papers that relate to the handover in UAV networks and that were published from 2019 to 2024 were chosen. The results from our studies show that machine learning is able to provide handover decision that are more efficient and robust than traditional/conventional methods of making handover decisions. Finally, several discussions based on several themes and the limitations of the studies were held.</div></div>","PeriodicalId":48609,"journal":{"name":"Engineering Science and Technology-An International Journal-Jestech","volume":"71 ","pages":"Article 102198"},"PeriodicalIF":5.4,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145159523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-24DOI: 10.1016/j.jestch.2025.102181
Shupeng Wang , Weigang Zhao , Song Gao , Kaize Xie , Xianli Ding , Juyang Wu
The widespread adoption of prefabricated structures faces two critical challenges: ensuring reliable connection performance while maintaining assembly efficiency, and meeting the stringent precision requirements for mechanical connectors during installation. To address these issues, this study develops an innovative steel connector mechanical system for prefabricated subway stations and establishes a comprehensive evaluation methodology integrating assembly process simulation with structural performance assessment. Through scaled model tests combining static and cyclic pushover loading, the research demonstrates that the proposed connector successfully reconciles assembly efficiency with structural reliability, showing minimal displacement during assembly and substantial load-bearing capacity in service conditions. The prefabricated system exhibits excellent seismic performance through a controlled yield mechanism where localized damage at frame corners protects critical joints, maintaining structural integrity up to interstory drift ratios exceeding the limit of 1/250 specified by the Chinese code GB 50909–2014. These findings provide both a validated technical solution and a systematic evaluation framework for advancing prefabricated underground construction.
{"title":"Development of a fully prefabricated subway station using scale experimental modeling","authors":"Shupeng Wang , Weigang Zhao , Song Gao , Kaize Xie , Xianli Ding , Juyang Wu","doi":"10.1016/j.jestch.2025.102181","DOIUrl":"10.1016/j.jestch.2025.102181","url":null,"abstract":"<div><div>The widespread adoption of prefabricated structures faces two critical challenges: ensuring reliable connection performance while maintaining assembly efficiency, and meeting the stringent precision requirements for mechanical connectors during installation. To address these issues, this study develops an innovative steel connector mechanical system for prefabricated subway stations and establishes a comprehensive evaluation methodology integrating assembly process simulation with structural performance assessment. Through scaled model tests combining static and cyclic pushover loading, the research demonstrates that the proposed connector successfully reconciles assembly efficiency with structural reliability, showing minimal displacement during assembly and substantial load-bearing capacity in service conditions. The prefabricated system exhibits excellent seismic performance through a controlled yield mechanism where localized damage at frame corners protects critical joints, maintaining structural integrity up to interstory drift ratios exceeding the limit of 1/250 specified by the Chinese code GB 50909–2014. These findings provide both a validated technical solution and a systematic evaluation framework for advancing prefabricated underground construction.</div></div>","PeriodicalId":48609,"journal":{"name":"Engineering Science and Technology-An International Journal-Jestech","volume":"71 ","pages":"Article 102181"},"PeriodicalIF":5.4,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145119165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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