Physics Open最新文献_第4页

Passive shimming method for permanent magnet MRI based on dynamic target magnetic field 基于动态目标磁场的永磁核磁共振被动摆振方法

Physics Open Pub Date : 2025-07-16 DOI: 10.1016/j.physo.2025.100296

Xin Liu , Jianli Meng , Chuangxin Huang , Qi Chen , Huiyuan Tan , Qiuliang Wang

{"title":"Passive shimming method for permanent magnet MRI based on dynamic target magnetic field","authors":"Xin Liu , Jianli Meng , Chuangxin Huang , Qi Chen , Huiyuan Tan , Qiuliang Wang","doi":"10.1016/j.physo.2025.100296","DOIUrl":"10.1016/j.physo.2025.100296","url":null,"abstract":"<div><div>To improve the imaging quality of permanent magnet MRI systems, passive shimming of the main magnetic field is necessary. However, traditional passive shimming methods face challenges such as overly stringent constraints and reliance on a single measurement volume. To address these issues, this paper proposes a dynamic target magnetic field (DTMF)-based shimming method for permanent magnet MRI systems. By dynamically adjusting the target magnetic field values, this method relaxes feasibility constraints and enhances the efficiency of obtaining viable solutions within the solution space. First, building on the fixed target magnetic field method (FTMF), we establish a shimming optimization model for the DTMF method and introduce an incremental revised simplex algorithm for solving the model. Next, a 0.2T permanent magnet MRI shimming experimental platform is constructed, involving the configuration of sampling points and shim pad placement. Finally, shimming experiments validate the effectiveness of the proposed method, and quantitative evaluations are conducted using assessment metrics for the shimming results. The results demonstrate that, compared to the fixed target magnetic field method, the DTMF method achieves a 29.17 % improvement in field homogeneity and a 24.24 % reduction in shim pad consumption. This method provides a more efficient, comprehensive, and flexible solution for enhancing the magnetic field homogeneity of permanent magnet MRI systems.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100296"},"PeriodicalIF":0.0,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144656038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Ternary PtFeCu alloys loaded on three-dimensional porous carbon for alkaline hydrogen evolution reaction 三维多孔碳负载三元PtFeCu合金进行碱性析氢反应

Physics Open Pub Date : 2025-07-11 DOI: 10.1016/j.physo.2025.100293

Jinlong He, Shuhua Zhao, Siyu Shang, Chenxi Zhou, Deying Wen

引用次数: 0

The relevant bosons at the liquid-solid transition 液固跃迁中的相关玻色子

Physics Open Pub Date : 2025-07-08 DOI: 10.1016/j.physo.2025.100291

Ulrich Köbler

{"title":"The relevant bosons at the liquid-solid transition","authors":"Ulrich Köbler","doi":"10.1016/j.physo.2025.100291","DOIUrl":"10.1016/j.physo.2025.100291","url":null,"abstract":"<div><div>Using the cubic alkali halogenides as model materials, it is shown that the cohesion of the solids up to the rather high melting temperatures, T<sub>m</sub>, is not by the inter-atomic interactions but by a boson field. A reasonable measure of the absolute interatomic interaction strength is given by the Debye-temperature, Θ<sub>D</sub>, which is much lower than T<sub>m</sub>. It is explained that in the wide temperature range Θ<sub>D</sub> < T < T<sub>m</sub>, the dynamics is the dynamics of a boson field. This is evidenced by the observed universality in the temperature dependence of heat capacity and relative thermal length changes, ΔL/L<sub>0</sub> below T<sub>m</sub>. The boson field orders at T<sub>m</sub> and defines the perfect long-range atomic order of the crystalline state. Upon ordering all bosons condense in the lowest quantum state (Bose-Einstein condensation). This is the highest possible thermodynamic order, and provides a plausible entropy argument for the exclusion of the interatomic interactions at order-disorder phase transitions. Additionally, ordered boson fields contract themselves to a finite volume such as a domain. The mosaic blocks, occurring in, practically, all crystalline solids, have to be viewed as the domains of the bosons that order at T<sub>m</sub>. Within each mosaic block, the bosons are in a stationary mode. The constricting force of the ordered boson field that compresses each mosaic block increasingly with decreasing temperature, guarantees the cohesion of the whole solid up to T<sub>m</sub>. Plausible arguments are given that the bosons that order at T<sub>m</sub> are elastic quadrupole radiation.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100291"},"PeriodicalIF":0.0,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144589270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Dynamic performance of magnetorheological Elastomer isolators for adaptive torsional vibration control in SDoF Systems: An experimental study 用于自适应扭转振动控制的磁流变弹性体隔振器动态性能的实验研究

Physics Open Pub Date : 2025-06-30 DOI: 10.1016/j.physo.2025.100289

Praveen Shenoy , Anarghya Ananda Murthy , K.V. Gangadharan , Ishwaragouda S. Patil

{"title":"Dynamic performance of magnetorheological Elastomer isolators for adaptive torsional vibration control in SDoF Systems: An experimental study","authors":"Praveen Shenoy , Anarghya Ananda Murthy , K.V. Gangadharan , Ishwaragouda S. Patil","doi":"10.1016/j.physo.2025.100289","DOIUrl":"10.1016/j.physo.2025.100289","url":null,"abstract":"<div><div>This paper presents an experimental investigation into the application of Magnetorheological Elastomer (MRE) isolators for torsional vibration isolation in a Single Degree of Freedom (SDoF) system. First, the characteristics have been extensively studied under torsional shear, followed by the derivation of the Parametric modeling for the system parameters using a fractional derivative-based Poynting-Thomson model. After investigating the dynamic properties of Magnetorheological Elastomers, an experimental test was custom-built using a MRE isolator for torsional vibration isolation in a single degree of freedom (SDoF) system. The system's input and output angular displacements were measured using the Serial Arrangement of Accelerometers (SAA) technique, which accurately captures the torsional modes of the system. The reduction in the system's transmissibility ratios, a measure of vibration isolation ability, was used to assess the effectiveness of the MRE isolators. The experimental results show that the system's natural Frequency shifts noticeably in response to different magnetic fields, significantly lowering transmissibility ratios. The impact of damping on the system was also investigated despite some discrepancies in the patterns. Results highlight a reduction in the amplitude transmissibility to 37.36 %. Co-relating to the field-dependent increase in the Stiffness, a frequency shift of 3 Hz is also observed.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100289"},"PeriodicalIF":0.0,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144570528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Electronic, magnetic, and optical properties of pentagonal Pt2Se4 monolayer doped with metalloid elements 掺杂类金属元素的五边形Pt2Se4单层的电子、磁性和光学性质

Physics Open Pub Date : 2025-06-25 DOI: 10.1016/j.physo.2025.100290

Mojtaba Gholami, Majid Ebrahimzadeh, Ali Sajjadian

{"title":"Electronic, magnetic, and optical properties of pentagonal Pt2Se4 monolayer doped with metalloid elements","authors":"Mojtaba Gholami, Majid Ebrahimzadeh, Ali Sajjadian","doi":"10.1016/j.physo.2025.100290","DOIUrl":"10.1016/j.physo.2025.100290","url":null,"abstract":"<div><div>The electronic, magnetic, and optical properties of the pentagonal Pt<sub>2</sub>Se<sub>4</sub> monolayer doped with metalloid elements (B, Si, Ge, As, Sb, Te, and At) as substitutes for Pt and Se atoms were explored using density functional theory. Our calculations of formation energies indicate that doping at the Se site is energetically preferred for all metalloids, with the Pt-site substitutions consistently exhibiting higher formation energies, averaging approximately 2.0 eV higher than the corresponding Se-site substitutions. Except for As, which induces a magnetic moment of approximately 0.5 μB in the system, the other dopants maintain the system's non-magnetic characteristics. The up-and-down-spin splitting of the As-pz orbital can be regarded as the primary reason for the emergence of the magnetic moment, a phenomenon absent in the other doped configurations. Apart from the B and Sb dopants, where new impurity states intersect the Fermi energy level, the remaining doped systems maintain semiconductor properties. All doped systems exhibit nearly transparent behavior in the visible energy range. However, incident light is effectively inhibited in the infrared region for B- and At-doped systems. The static dielectric constants ϵ<sub>1</sub>(0) for Pt<sub>2</sub>Se<sub>4</sub> doped with As, At, B, Ge, Sb, Te, and Si are reported as 1.08, 1.76, 1, 1.17, 1, and 1, respectively. These varied findings hold promise for applications in spintronics, optoelectronics, and the advancement of optical nanostructures.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100290"},"PeriodicalIF":0.0,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144523297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Structural, optoelectronic, mechanical and thermodynamic properties of AgMgX3(X= Cl, Br): A first principles study AgMgX3（X= Cl, Br）的结构、光电、力学和热力学性质：第一性原理研究

Physics Open Pub Date : 2025-06-25 DOI: 10.1016/j.physo.2025.100288

Md Ashikur Rahman, Md Jobayer Hassan, Jerin Haider, Md Meskat Ali, Md Mahmudul Hasan, Md Alamgir Badsha

{"title":"Structural, optoelectronic, mechanical and thermodynamic properties of AgMgX3(X= Cl, Br): A first principles study","authors":"Md Ashikur Rahman, Md Jobayer Hassan, Jerin Haider, Md Meskat Ali, Md Mahmudul Hasan, Md Alamgir Badsha","doi":"10.1016/j.physo.2025.100288","DOIUrl":"10.1016/j.physo.2025.100288","url":null,"abstract":"<div><div>Maintaining a contamination-free environment is crucial for researchers developing industrial products. The lead-free perovskite compounds, AgMgX<sub>3</sub> (X = Cl, Br), have utilized density functional theory (DFT) to assess their properties. The stability of these compounds is confirmed by the Goldsmith tolerance factor and negative formation energy. For AgMgCl<sub>3</sub>, the calculated indirect band gap values are 1.655 eV and 1.228 eV, while AgMgBr<sub>3</sub> shows band gap values of 0.889 eV and 0.453 eV, as determined by the GGA-PBE and LDA-CAPZ functionals, respectively. In addition, the hybrid functional HSE06 yields a band gap of 1.80 eV for AgMgCl<sub>3</sub> and 1.035 eV for AgMgBr<sub>3</sub>. Both materials exhibit p-type semiconductor behavior. Moreover, these compounds demonstrate a high absorption coefficient, good optical conductivity, and low reflectivity within the visible spectral range, making them promising candidates for various applications. Their mechanical stability and ductility support the fabrication of thin films for use in heterostructure devices. The imaginary phonon frequency indicates dynamical instability, and ab initio molecular dynamics (AIMD) reaffirm their elastic stability. Both perovskites exhibit anharmonic behavior at higher temperatures below melting point and high Debye temperatures suggest strong thermal stability. Consequently, the properties of these materials may pave the way for new optoelectronic applications.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100288"},"PeriodicalIF":0.0,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144490960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Optical OTFS waveform PAPR analysis for high order modulation employing CNN, DNN, and AE machine learning algorithms under a variety of channel scenarios 采用CNN、DNN和AE机器学习算法的高阶调制光学OTFS波形PAPR分析

Physics Open Pub Date : 2025-06-18 DOI: 10.1016/j.physo.2025.100284

Arun Kumar , Nishant Gaur , Aziz Nanthaamornphong

{"title":"Optical OTFS waveform PAPR analysis for high order modulation employing CNN, DNN, and AE machine learning algorithms under a variety of channel scenarios","authors":"Arun Kumar , Nishant Gaur , Aziz Nanthaamornphong","doi":"10.1016/j.physo.2025.100284","DOIUrl":"10.1016/j.physo.2025.100284","url":null,"abstract":"<div><div>Optical orthogonal time–frequency space (OTFS) modulation is a future technique for optical wireless communication with high mobility. Nevertheless, the high peak-to-average power ratio (PAPR) of OTFS modulation severely degrades the system performance, particularly in the case of high-order modulation formats. This paper proposes an algorithm for machine-learning (ML)-based PAPR reduction dedicated to optical OTFS under varying channel conditions, such as turbulence and multipath fading. The proposed method utilizes deep learning models to maximize signal processing and suppress peak-power variations, while ensuring signal integrity. The simulations result prove that the proposed method attains a PAPR reduction of about 4 dB and 3.8 dB for 256-QAM and 2.2 dB and 1.6 dB for 64-QAM under a Rayleigh and Rician channel at a Complementary Cumulative Distribution Function (CCDF) of 10-5, better than conventional PAPR reduction methods. Power Spectral Density (PSD) analysis verifies that ML-based techniques, such as deep neural networks (DNN), convolutional neural networks (CNN), and autoencoders (AE), are spectrally efficient with negligible out-of-band radiation of -1070 and -1470 for 256QAM with diverse channel conditions. Moreover, Bit Error Rate (BER) performance tests demonstrate an SNR improvement of 8.2 dB and 3.9 at a BER of 10-5, guaranteeing error-free data transmission for diverse mobility scenarios. Furthermore, the proposed methods are compared with partial transmission schemes (PTS), selective mapping (SLM), tone reservation (TR), companding, clipping, and filtering (C&F). The numerical results emphasize the capability of ML to improve PAPR performance without PSD and BER performance. The results are significant for future optical wireless networks, where high data rates must be sustained and nonlinear distortion minimized.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100284"},"PeriodicalIF":0.0,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144480113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A comparative artificial neural networks for Schwarzschild black hole (SBH) radius 史瓦西黑洞（SBH）半径的比较人工神经网络

Physics Open Pub Date : 2025-06-12 DOI: 10.1016/j.physo.2025.100287

Khalil Ur Rehman , Wasfi Shatanawi , Weam G. Alharbi

{"title":"A comparative artificial neural networks for Schwarzschild black hole (SBH) radius","authors":"Khalil Ur Rehman , Wasfi Shatanawi , Weam G. Alharbi","doi":"10.1016/j.physo.2025.100287","DOIUrl":"10.1016/j.physo.2025.100287","url":null,"abstract":"<div><div>It is consensus among researchers that the data for the black holes is complicated and extremely non-linear in nature. Therefore, it remains a challenging task for them to predict the key characteristics of concerned black holes accurately. The present work offers artificial neural networks assistance in the context of a choice of training functions for the prediction of astrophysical phenomena like the event horizon and radius of black holes. To be more specific, we considered the Schwarzschild black hole as the simplest solution of Einstein's field equations. The Schwarzschild radius and masses are chosen in the last and first layers of the neural networks model, respectively. Two various training functions namely Levenberg-Marquardt training algorithm (LMTA) and Scaled Conjugate Gradient training algorithms (SCGTA) are used. We have observed that the LMTA achieved significantly lower error rates, suggesting a better fit and stronger learning capabilities from the solar masses of black holes. Furthermore, the close alignment between the ANN-predicted and actual Schwarzschild black hole radius demonstrates the LMTA model holds the ability to generalize effectively across unseen masses of black holes.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100287"},"PeriodicalIF":0.0,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144297259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Conservation relationship bridging entropy and information 连接熵和信息的守恒关系

Physics Open Pub Date : 2025-06-11 DOI: 10.1016/j.physo.2025.100285

Stoyan C. Russev

引用次数: 0

Enhanced electrical and magnetic properties of Gd-doped Ni-Zn ferrites for energy storage applications 用于储能应用的钆掺杂镍锌铁氧体的增强电学和磁性能

Physics Open Pub Date : 2025-06-10 DOI: 10.1016/j.physo.2025.100286

P. Shanthakumari , Naveena Gadwala , K. Sathi Reddy , Sathish Boddolla

{"title":"Enhanced electrical and magnetic properties of Gd-doped Ni-Zn ferrites for energy storage applications","authors":"P. Shanthakumari , Naveena Gadwala , K. Sathi Reddy , Sathish Boddolla","doi":"10.1016/j.physo.2025.100286","DOIUrl":"10.1016/j.physo.2025.100286","url":null,"abstract":"<div><div>Gadolinium (Gd<sup>3+</sup>)-substituted Ni<sub>0</sub>.<sub>8</sub>Zn<sub>0</sub>.<sub>2</sub>Gd<sub>x</sub>Fe<sub>2-x</sub>O<sub>4</sub> spinel ferrites (x = 0.00, 0.05, 0.10, 0.15, 0.20) were synthesized using the citrate-gel auto-combustion technique. X-ray diffraction confirmed the formation of a cubic spinel structure, with an increase in average crystallite size upon Gd<sup>3+</sup> substitution, while the lattice parameter showed a decreasing trend. Field emission scanning electron microscopy revealed agglomerated particles with homogeneous dispersion, and a reduction in grain size due to doping. Energy dispersive X-ray spectroscopy confirmed the presence of the expected elements. Fourier-transform infrared spectroscopy identified tetrahedral and octahedral vibrational bonds (ν<sub>1</sub> and ν<sub>2</sub>), from which the force constants (K<sub>T</sub> and K<sub>O</sub>) were determined. Electrical measurements, including dielectric constant, dielectric loss, and AC conductivity, were conducted at room temperature, showing a decreasing trend with increasing Gd<sup>3+</sup> content. Magnetic characterization indicated a reduction in saturation magnetization and an increase in coercivity. The incorporation of Gd<sup>3+</sup> into Ni-Zn ferrites notably influenced both the electrical and magnetic properties of the synthesized materials. Which are suitable for communication and energy storage systems.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100286"},"PeriodicalIF":0.0,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144272023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0