Pub Date : 2025-12-30DOI: 10.1109/TMAG.2025.3649481
Takenori Atsumi;Shota Yabui
Modern hard disk drives (HDDs) employ triple-stage actuators (TSAs) to meet demanding data storage requirements. The control systems for these actuators are typically designed with a decoupled structure to simplify the control design process. However, a significant challenge remains: achieving robust performance against system perturbations while maintaining this decoupled structure. This article proposes a novel control design method that addresses this issue. Our approach allows for the design of a robust control system for TSA systems without the need for complex, unintuitive algorithms, or cumbersome design procedures, which are often difficult to implement in an industrial setting. By applying a robust loop-shaping framework, specifically, the robust controller bode (RCBode) plot, within the domain of classical control theory, our proposed method enables designers to achieve high-performance robust control simply by shaping a filter based on clear guidelines on a Bode plot, thereby avoiding complex modeling and intricate mathematical derivations. The effectiveness of the proposed method is validated through simulations based on the HDD benchmark problem, demonstrating excellent robust performance against disturbances encountered in data center environments.
{"title":"Robust Loop-Shaping Method for Decoupled Control Systems of HDD Triple-Stage Actuators Using RCBode Plot","authors":"Takenori Atsumi;Shota Yabui","doi":"10.1109/TMAG.2025.3649481","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3649481","url":null,"abstract":"Modern hard disk drives (HDDs) employ triple-stage actuators (TSAs) to meet demanding data storage requirements. The control systems for these actuators are typically designed with a decoupled structure to simplify the control design process. However, a significant challenge remains: achieving robust performance against system perturbations while maintaining this decoupled structure. This article proposes a novel control design method that addresses this issue. Our approach allows for the design of a robust control system for TSA systems without the need for complex, unintuitive algorithms, or cumbersome design procedures, which are often difficult to implement in an industrial setting. By applying a robust loop-shaping framework, specifically, the robust controller bode (RCBode) plot, within the domain of classical control theory, our proposed method enables designers to achieve high-performance robust control simply by shaping a filter based on clear guidelines on a Bode plot, thereby avoiding complex modeling and intricate mathematical derivations. The effectiveness of the proposed method is validated through simulations based on the HDD benchmark problem, demonstrating excellent robust performance against disturbances encountered in data center environments.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 2","pages":"1-10"},"PeriodicalIF":1.9,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-12-29DOI: 10.1109/TMAG.2025.3645176
{"title":"IEEE Magnetics Society Information","authors":"","doi":"10.1109/TMAG.2025.3645176","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3645176","url":null,"abstract":"","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 1","pages":"C2-C2"},"PeriodicalIF":1.9,"publicationDate":"2025-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11318117","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145847831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
While three-dimensional magnetic recording (3DMR) multiplies the capacity of hard disk drives (HDDs) by stacking multiple recording layers perpendicularly, it also complicates the magnetization interactions between adjacent bits and introduces more interference. In this work, we determine the detrimental bit-pair patterns that induce severe writing interference in dual-layer 3DMR via micromagnetic simulation, and we propose a design of constrained codes to enhance recording reliability by restricting these patterns. Our results show that the coding scheme improves the media signal-to-noise ratio (SNR) by up to 17.93% and reduces the post-detection bit error rate (BER) by up to 99.67% to nearly 10−5 with user areal density between 1.6 and 3.2 Tb/in2.
{"title":"Reduction of Writing Interference in Three-Dimensional Magnetic Recording by Constrained Codes","authors":"Yugen Jian;Yuqian Zhao;Wei Yu;Ke Luo;Jincai Chen;Xuanyao Fong","doi":"10.1109/TMAG.2025.3649282","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3649282","url":null,"abstract":"While three-dimensional magnetic recording (3DMR) multiplies the capacity of hard disk drives (HDDs) by stacking multiple recording layers perpendicularly, it also complicates the magnetization interactions between adjacent bits and introduces more interference. In this work, we determine the detrimental bit-pair patterns that induce severe writing interference in dual-layer 3DMR via micromagnetic simulation, and we propose a design of constrained codes to enhance recording reliability by restricting these patterns. Our results show that the coding scheme improves the media signal-to-noise ratio (SNR) by up to 17.93% and reduces the post-detection bit error rate (BER) by up to 99.67% to nearly 10−5 with user areal density between 1.6 and 3.2 Tb/in2.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 3","pages":"1-7"},"PeriodicalIF":1.9,"publicationDate":"2025-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147383115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-12-24DOI: 10.1109/TMAG.2025.3647779
Amrutha R Menon;Hemprasad Yashwant Patil;Ashutosh Mahajan;Niroj Kumar Sahu
This work presents, for the first time, a physics-informed neural network (PINN) model for magnetic hyperthermia, a promising non-invasive cancer therapy known for its high efficacy and minimal side effects. Effective cancer cell destruction requires heating to 42 °C-45 °C. The heat generated by magnetic nanoparticles (MNPs) under an alternating magnetic field depends strongly on their physicochemical properties. Hence, the optimization of MNP for effective heat generation remains a key challenge and constitutes the fundamental motivation of this study. In this work, we study and compare various approaches using regression models, artificial neural network (ANN), and PINN to address the challenges associated with magnetic fluid hyperthermia (MFH) prediction and analysis. The model incorporates input parameters, including particle size, saturation magnetization, magnetic field intensity, frequency, specific heat of fluid, nanoparticle (NP) concentration, and time, to predict temperature evolution as the output. The dataset is compiled from our published research work, comprising 3690 data points, ensuring sufficient variability and robustness for model training and evaluation. Our PINN model shows an excellent R2 value of around 0.98 against the test data.
{"title":"Physics-Informed and Data-Driven Machine Learning for Magnetic Hyperthermia of Fe3O4 Nanoparticles","authors":"Amrutha R Menon;Hemprasad Yashwant Patil;Ashutosh Mahajan;Niroj Kumar Sahu","doi":"10.1109/TMAG.2025.3647779","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3647779","url":null,"abstract":"This work presents, for the first time, a physics-informed neural network (PINN) model for magnetic hyperthermia, a promising non-invasive cancer therapy known for its high efficacy and minimal side effects. Effective cancer cell destruction requires heating to 42 °C-45 °C. The heat generated by magnetic nanoparticles (MNPs) under an alternating magnetic field depends strongly on their physicochemical properties. Hence, the optimization of MNP for effective heat generation remains a key challenge and constitutes the fundamental motivation of this study. In this work, we study and compare various approaches using regression models, artificial neural network (ANN), and PINN to address the challenges associated with magnetic fluid hyperthermia (MFH) prediction and analysis. The model incorporates input parameters, including particle size, saturation magnetization, magnetic field intensity, frequency, specific heat of fluid, nanoparticle (NP) concentration, and time, to predict temperature evolution as the output. The dataset is compiled from our published research work, comprising 3690 data points, ensuring sufficient variability and robustness for model training and evaluation. Our PINN model shows an excellent R2 value of around 0.98 against the test data.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 2","pages":"1-10"},"PeriodicalIF":1.9,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-12-23DOI: 10.1109/TMAG.2025.3647738
Limei Yan;Yingjie Li;Yuanyuan Li;Jing Liu;Guoqiang Liu
The state of blood flow in blood vessels has an inseparable relationship with cardiovascular diseases (CVDs). To facilitate convenient blood flow monitoring, this study investigates the relationship between blood flow and the electric field in an electromagnetic blood flowmeter using a permanent magnet as the excitation source through modeling and simulation. First, for the case of a uniform magnetic field and noninvasive measurement, a mathematical model of the target blood region was established, providing a numerical relationship between blood flow and the potential distribution generated under a uniform magnetic field. Subsequently, the effects and offsets caused by a nonuniform magnetic field generated by a permanent magnet were analyzed, and the corresponding models were simulated using COMSOL. By combining the simulation results with numerical solutions, a quantitative expression was constructed to describe the relationship between the voltage measured across symmetric electrodes and blood flow under a nonuniform magnetic field. Finally, experimental measurements were conducted under practical conditions, yielding a measured voltage within 5 μV of simulated predictions, thereby providing a valuable reference for the further development and portable application of electromagnetic blood flowmeters.
{"title":"Noninvasive Blood Flow Measurement Using Electromagnetic Method Under Nonuniform Magnetic Fields","authors":"Limei Yan;Yingjie Li;Yuanyuan Li;Jing Liu;Guoqiang Liu","doi":"10.1109/TMAG.2025.3647738","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3647738","url":null,"abstract":"The state of blood flow in blood vessels has an inseparable relationship with cardiovascular diseases (CVDs). To facilitate convenient blood flow monitoring, this study investigates the relationship between blood flow and the electric field in an electromagnetic blood flowmeter using a permanent magnet as the excitation source through modeling and simulation. First, for the case of a uniform magnetic field and noninvasive measurement, a mathematical model of the target blood region was established, providing a numerical relationship between blood flow and the potential distribution generated under a uniform magnetic field. Subsequently, the effects and offsets caused by a nonuniform magnetic field generated by a permanent magnet were analyzed, and the corresponding models were simulated using COMSOL. By combining the simulation results with numerical solutions, a quantitative expression was constructed to describe the relationship between the voltage measured across symmetric electrodes and blood flow under a nonuniform magnetic field. Finally, experimental measurements were conducted under practical conditions, yielding a measured voltage within 5 μV of simulated predictions, thereby providing a valuable reference for the further development and portable application of electromagnetic blood flowmeters.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 2","pages":"1-11"},"PeriodicalIF":1.9,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-12-22DOI: 10.1109/TMAG.2025.3646805
Jianwei Wang;Zheng Zhang;Jiaxing Peng;Zheng Cheng;Panpan Zuo;Qinwei Li;Tieqiao Hu
In this article, a low-cost magnetic-field probe ($H$ -field probe) with enhanced gain flatness is designed, fabricated, and calibrated. The symmetrical probe body structure, combined with a side-plug sub miniature version A (SMA) connector, enables the proposed $H$ -field probe to measure the tangential magnetic fields ($H_{x}$ and $H_{y}$ ) in one-time measurement via coaxial rotation, resulting in an enhanced measurement efficiency of about 30% without reloading the probe repeatedly during the measurement. The designed loop aperture and symmetric chamfered edge (SCE) effectively suppress resonances and ripples, achieving an average fluctuation of about 1.25 dB and a maximum fluctuation of less than 2 dB in terms of the proposed $H$ -field probe's $left|S_{21}right|$ . The proposed $H$ -field probe maintains a high common-mode suppression of more than 30 dB within 9 kHz-20 GHz and a 13.23 dB suppression to the differential-mode coupling at 5 GHz with an extremely low cost.
{"title":"A Low-Cost H-Field Probe With Coaxial Rotation for Magnetic-Field Scanning","authors":"Jianwei Wang;Zheng Zhang;Jiaxing Peng;Zheng Cheng;Panpan Zuo;Qinwei Li;Tieqiao Hu","doi":"10.1109/TMAG.2025.3646805","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3646805","url":null,"abstract":"In this article, a low-cost magnetic-field probe (<inline-formula> <tex-math>$H$ </tex-math></inline-formula>-field probe) with enhanced gain flatness is designed, fabricated, and calibrated. The symmetrical probe body structure, combined with a side-plug sub miniature version A (SMA) connector, enables the proposed <inline-formula> <tex-math>$H$ </tex-math></inline-formula>-field probe to measure the tangential magnetic fields (<inline-formula> <tex-math>$H_{x}$ </tex-math></inline-formula> and <inline-formula> <tex-math>$H_{y}$ </tex-math></inline-formula>) in one-time measurement via coaxial rotation, resulting in an enhanced measurement efficiency of about 30% without reloading the probe repeatedly during the measurement. The designed loop aperture and symmetric chamfered edge (SCE) effectively suppress resonances and ripples, achieving an average fluctuation of about 1.25 dB and a maximum fluctuation of less than 2 dB in terms of the proposed <inline-formula> <tex-math>$H$ </tex-math></inline-formula>-field probe's <inline-formula> <tex-math>$left|S_{21}right|$ </tex-math></inline-formula>. The proposed <inline-formula> <tex-math>$H$ </tex-math></inline-formula>-field probe maintains a high common-mode suppression of more than 30 dB within 9 kHz-20 GHz and a 13.23 dB suppression to the differential-mode coupling at 5 GHz with an extremely low cost.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 2","pages":"1-7"},"PeriodicalIF":1.9,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Using the seed-mediated high-temperature decomposition method, we synthesized $mathrm{CoFe}_2 mathrm{O}_4 text {@} mathrm{NiFe}_2 mathrm{O}_4$ core/shell nanoparticles with controlled shell thicknesses from $sim 1$ to 6 nm and evaluated their performance in magnetic hyperthermia. A clear enhancement in heating efficiency was observed, with specific absorption rate (SAR) values increasing from $sim 40 mathrm{~W} cdot mathrm{~g}^{-1}$ for bare $mathrm{CoFe}_2 mathrm{O}_4$ to $sim 80 mathrm{~W} cdot mathrm{~g}^{-1}$ for the thickest-shell sample. This trend is attributed to optimized magnetic anisotropy and particle volume, enhancing thermal stability and energy dissipation under alternating magnetic fields (AMFs) below Hergt-Dutz limit. These findings support the strategic design of hard and soft ferrite architectures for biomedical heating applications. Although the particles are capped with oleate ligands from the synthesis, these results highlight the tunability of hard and soft ferrite systems and offer insight into the future design of biocompatible hyperthermia agents.
{"title":"Shell Thickness-Dependent Anisotropy in CoFe2O4@NiFe2O4 Core/Shell Nanoparticles for Magnetic Heating","authors":"A. Omelyanchik;S. Villa;F. Canepa;G. Singh;F. Brero;A. Lascialfari;Ž. Fabriciová;P. Hrubovčák;A. Zeleňáková;D. Peddis","doi":"10.1109/TMAG.2025.3646767","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3646767","url":null,"abstract":"Using the seed-mediated high-temperature decomposition method, we synthesized <inline-formula> <tex-math>$mathrm{CoFe}_2 mathrm{O}_4 text {@} mathrm{NiFe}_2 mathrm{O}_4$ </tex-math></inline-formula> core/shell nanoparticles with controlled shell thicknesses from <inline-formula> <tex-math>$sim 1$ </tex-math></inline-formula> to 6 nm and evaluated their performance in magnetic hyperthermia. A clear enhancement in heating efficiency was observed, with specific absorption rate (SAR) values increasing from <inline-formula> <tex-math>$sim 40 mathrm{~W} cdot mathrm{~g}^{-1}$ </tex-math></inline-formula> for bare <inline-formula> <tex-math>$mathrm{CoFe}_2 mathrm{O}_4$ </tex-math></inline-formula> to <inline-formula> <tex-math>$sim 80 mathrm{~W} cdot mathrm{~g}^{-1}$ </tex-math></inline-formula> for the thickest-shell sample. This trend is attributed to optimized magnetic anisotropy and particle volume, enhancing thermal stability and energy dissipation under alternating magnetic fields (AMFs) below Hergt-Dutz limit. These findings support the strategic design of hard and soft ferrite architectures for biomedical heating applications. Although the particles are capped with oleate ligands from the synthesis, these results highlight the tunability of hard and soft ferrite systems and offer insight into the future design of biocompatible hyperthermia agents.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 2","pages":"1-6"},"PeriodicalIF":1.9,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-12-22DOI: 10.1109/TMAG.2025.3646843
Viviana Guzmán-Castillo;Adrian Emmanuel Reyes-Resendiz;Pedro Martínez-Ortiz;Jose Alberto Perez-Benitez
In this work, a novel finite element formulation for the numerical solution of 3-D magnetostatic problems is presented. The formulation is derived from the classical vector potential equation of magnetostatics, which is reformulated through the application of vector calculus identities. The resulting weak form is discretized using a nodal-based approach, yielding a system of linear equations. The corresponding stiffness matrix comprises two distinct contributions: one associated with the bulk material properties and the other arising from the interfaces between different domains. The classic and proposed formulations were implemented in Python, without using any finite element specialized library. Numerical simulations demonstrate that the magnetic flux density computed with the proposed formulation closely matches that obtained from the conventional approach, with the difference that the proposed method exhibits a pronounced attenuation near the boundaries. This formulation may provide advantages in terms of solution stability and convergence, and could ultimately enable the computation of a physically meaningful magnetic potential suitable for gauge-dependent evaluations of physical quantities, thereby reducing the overall computational cost.
{"title":"A New Formulation for 3-D Magnetostatic Problems: Finite Element Analysis","authors":"Viviana Guzmán-Castillo;Adrian Emmanuel Reyes-Resendiz;Pedro Martínez-Ortiz;Jose Alberto Perez-Benitez","doi":"10.1109/TMAG.2025.3646843","DOIUrl":"https://doi.org/10.1109/TMAG.2025.3646843","url":null,"abstract":"In this work, a novel finite element formulation for the numerical solution of 3-D magnetostatic problems is presented. The formulation is derived from the classical vector potential equation of magnetostatics, which is reformulated through the application of vector calculus identities. The resulting weak form is discretized using a nodal-based approach, yielding a system of linear equations. The corresponding stiffness matrix comprises two distinct contributions: one associated with the bulk material properties and the other arising from the interfaces between different domains. The classic and proposed formulations were implemented in Python, without using any finite element specialized library. Numerical simulations demonstrate that the magnetic flux density computed with the proposed formulation closely matches that obtained from the conventional approach, with the difference that the proposed method exhibits a pronounced attenuation near the boundaries. This formulation may provide advantages in terms of solution stability and convergence, and could ultimately enable the computation of a physically meaningful magnetic potential suitable for gauge-dependent evaluations of physical quantities, thereby reducing the overall computational cost.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"62 3","pages":"1-17"},"PeriodicalIF":1.9,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147383118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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