Physics Open最新文献_第9页

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

Q2 Physics and Astronomy

Physics Open

Pub Date : 2025-08-01 Epub Date: 2025-06-30 DOI: 10.1016/j.physo.2025.100289

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

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.

本文对磁流变弹性体（MRE）隔振器在单自由度系统扭振中的应用进行了实验研究。首先，广泛研究了扭转剪切作用下的特性，然后利用基于分数阶导数的Poynting-Thomson模型推导了系统参数的参数化建模。在研究了磁流变弹性体的动态特性后，在单自由度（SDoF）系统中使用MRE隔振器进行了扭振隔离的实验测试。采用加速度计串行排列（SAA）技术测量了系统的输入和输出角位移，该技术准确捕获了系统的扭转模态。降低系统的传递率，隔振能力的一个指标，被用来评估MRE隔振器的有效性。实验结果表明，系统的固有频率在不同磁场下有明显的位移，显著降低了传输率。尽管在模式上存在一些差异，但阻尼对系统的影响也进行了研究。结果显示，振幅传递率降低到37.36%。与场相关的刚度增加有关，还观察到3hz的频移。

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引用次数: 0

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

Q2 Physics and Astronomy

Physics Open

Pub Date : 2025-08-01 Epub Date: 2025-07-16 DOI: 10.1016/j.physo.2025.100296

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

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.

为了提高永磁核磁共振成像系统的成像质量，需要对主磁场进行被动调光。然而，传统的被动摆振方法面临着过于严格的约束和对单一测量体积的依赖等挑战。为了解决这些问题，本文提出了一种基于动态目标磁场（DTMF）的永磁核磁共振系统摆振方法。该方法通过动态调整目标磁场值，放宽了可行性约束，提高了求解空间内可行解的效率。首先，在固定目标磁场法（FTMF）的基础上，建立了DTMF方法的摆振优化模型，并引入增量修正单纯形算法求解该模型。其次，构建0.2T永磁MRI摆振实验平台，包括采样点的配置和摆振垫的放置。最后，通过浮波实验验证了该方法的有效性，并利用评价指标对浮波结果进行了定量评价。结果表明，与固定目标磁场法相比，DTMF方法的磁场均匀性提高了29.17%，垫片消耗降低了24.24%。该方法为增强永磁MRI系统的磁场均匀性提供了一种更高效、全面、灵活的解决方案。

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引用次数: 0

Size and liquid-substrate interfacial energy effects on melting temperature and band gap in CdSe Nanoparticles: A comparative study of cylindrical and spherical geometries 尺寸和液体-衬底界面能对CdSe纳米颗粒熔化温度和带隙的影响：圆柱形和球形几何形状的比较研究

Q2 Physics and Astronomy

Physics Open

Pub Date : 2025-08-01 Epub Date: 2025-07-17 DOI: 10.1016/j.physo.2025.100295

Gebru Tesfaye Sherka, Habte Dulla Berry

This paper presents a theoretical comparison examining the effects of nanoparticle size and liquid-substrate interfacial energy on the melting temperature and band gap of cadmium selenide (CdSe) nanoparticles supported on a glass substrate, analyzing both cylindrical and spherical shapes. Using a simple thermodynamic model, this study investigates the influence of nanoparticle size and liquid-substrate interfacial energy on the melting temperature and band gap of supported CdSe nanoparticles with cylindrical and spherical geometries. The model incorporates surface and interfacial energies and wetting parameters to derive analytical expressions for the variations in melting temperature and band gap as functions of nanoparticle size and substrate interaction for both shapes. Results show that the melting temperature decreases with decreasing particle size. In contrast, the band gap increases, but the extent of this dependence varies between cylindrical and spherical geometries, which means nanoparticles with higher surface curvatures (cylindrical shape) exhibit lower melting temperatures than nanoparticles with lower surface curvatures (spherical shape). Furthermore, stronger liquid-substrate interfacial interactions lead to greater melting point depression, while weaker interactions stabilize the nanoparticles, resulting in higher melting temperatures in both geometries. The band gap shows a strong quantum confinement effect in smaller nanoparticles, while their geometry and substrate interactions further influence this trend. The study compares theoretical predictions with existing experimental data and models for unsupported nanoparticles, emphasizing how interfacial energy and shape critically affect the thermal and optical characteristics of CdSe nanomaterials. These findings provide valuable guidance for enhancing the performance and durability of CdSe-based devices in photovoltaic systems, optoelectronic components, and nanosensors.

本文从理论上比较了纳米颗粒尺寸和液基界面能对玻璃基板上硒化镉（CdSe）纳米颗粒熔化温度和带隙的影响，分析了圆柱形和球形两种形状。利用简单的热力学模型，研究了纳米颗粒尺寸和液基界面能对圆柱形和球形负载型CdSe纳米颗粒熔化温度和带隙的影响。该模型结合表面和界面能以及润湿参数，推导出两种形状的纳米颗粒尺寸和衬底相互作用对熔化温度和带隙变化的解析表达式。结果表明，熔点温度随晶粒尺寸的减小而降低。相比之下，带隙增加，但这种依赖程度在圆柱形和球形几何形状之间有所不同，这意味着具有较高表面曲率的纳米颗粒（圆柱形）比具有较低表面曲率的纳米颗粒（球形）具有更低的熔化温度。此外，更强的液体-衬底界面相互作用导致更大的熔点下降，而更弱的相互作用使纳米颗粒稳定，导致两种几何形状的更高熔化温度。带隙在较小的纳米颗粒中表现出很强的量子约束效应，而它们的几何形状和衬底相互作用进一步影响了这一趋势。该研究将理论预测与现有的无负载纳米颗粒的实验数据和模型进行了比较，强调了界面能和形状如何对CdSe纳米材料的热学和光学特性产生关键影响。这些发现为提高光电系统、光电元件和纳米传感器中基于cdse的器件的性能和耐久性提供了有价值的指导。

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引用次数: 0

First-principles calculations to investigate electronic, optical and thermo-elastic features of monoclinic AgCuO2 alloy 用第一性原理计算研究单斜AgCuO2合金的电子、光学和热弹性特性

Q2 Physics and Astronomy

Physics Open

Pub Date : 2025-08-01 Epub Date: 2025-07-23 DOI: 10.1016/j.physo.2025.100299

Md. Alomgir Hossain , M.N.H. Liton , M.S.I. Sarker , M.M. Rahman , M.K.R. Khan

Structural, electronic, mechanical and optical properties of AgCuO₂ have been unveiled through first principles calculations based on density functional theory (DFT) via CASTEP code. The evaluated lattice parameters agree with the previous theoretical and experimental observations for the monoclinic structure of AgCuO₂. The electronic band structure and density of states (DOS) analysis at the Fermi level confirms the metallic behavior of AgCuO₂. Besides, the partial density of states (PDOS) reveals that Cu-3d and O-2p orbitals are primarily responsible for the formation of metallic bands. Various optical properties have been calculated along different polarization directions, and the obtained results re-confirmed the metallic nature of AgCuO₂. All the optical spectra exhibit anisotropic behavior, indicating potential applications in direction-dependent optical devices. The high reflectivity in the infrared and visible regions suggests that AgCuO₂ can be potentially used in optical mirrors and thermal barrier coatings. Analysis of additional optical parameters indicates that AgCuO₂ could be a promising candidate for optoelectronic devices. The calculated elastic tensor satisfies the stability criteria, confirming the stability of the monoclinic structure. The estimated elastic parameters suggest that AgCuO₂ is soft, ductile and anisotropic. A mixed bonding character with dominating ionic contribution in the crystal system is established from elastic constant and Mulliken bond analysis. The calculated lower value of Debye temperature specifies that AgCuO₂ is a soft material with lower lattice thermal conductivity. The weaker interatomic bonding properties due to lower Debye temperature, low melting temperature and minimum thermal conductivity make it a possible candidate for TCB material.

通过CASTEP程序，基于密度泛函理论（DFT）的第一性原理计算，揭示了AgCuO2的结构、电子、机械和光学性质。计算得到的晶格参数与以往对AgCuO2单斜结构的理论和实验观测结果一致。费米能级的电子能带结构和态密度（DOS）分析证实了AgCuO2的金属行为。此外，偏态密度（PDOS）表明Cu-3d和O-2p轨道是金属能带形成的主要原因。沿不同偏振方向计算了各种光学性质，所得结果再次证实了AgCuO2的金属性质。所有光谱都表现出各向异性行为，表明在方向相关光学器件中的潜在应用。红外和可见光区的高反射率表明，AgCuO2可以潜在地用于光学反射镜和热障涂层。附加光学参数的分析表明，AgCuO2可能是光电子器件的有前途的候选者。计算得到的弹性张量满足稳定性判据，证实了单斜结构的稳定性。估算的弹性参数表明AgCuO2具有软质、延性和各向异性。通过弹性常数和Mulliken键分析，建立了晶体体系中以离子贡献为主的混合键特征。计算得到的Debye温度下限说明AgCuO2是一种晶格导热系数较低的软质材料。由于较低的德拜温度、较低的熔融温度和最小的导热系数，使其原子间键性能较弱，使其成为TCB材料的可能候选材料。

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引用次数: 0

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

Q2 Physics and Astronomy

Physics Open

Pub Date : 2025-08-01 Epub Date: 2025-07-08 DOI: 10.1016/j.physo.2025.100291

Ulrich Köbler

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_m, 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_D, which is much lower than T_m. It is explained that in the wide temperature range Θ_D < T < T_m, 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/L₀ below T_m. The boson field orders at T_m 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_m. 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_m. Plausible arguments are given that the bosons that order at T_m are elastic quadrupole radiation.

以立方碱卤化物为模型材料，证明了固体在较高熔点Tm之前的内聚不是由原子间相互作用引起的，而是由玻色子场引起的。德拜温度ΘD是原子间绝对相互作用强度的合理度量，远低于Tm。说明在较宽的温度范围内ΘD <；T & lt;Tm，动力学是玻色子场的动力学。热容和相对热长变化在温度依赖性中的普遍性证明了这一点，ΔL/L0低于Tm。玻色子场在Tm处有序，并定义了晶体状态的完美远程原子有序。在排序时，所有玻色子都在最低量子态（玻色-爱因斯坦凝聚）中凝聚。这是最高可能的热力学顺序，并为排除有序-无序相变中的原子间相互作用提供了一个可信的熵论证。此外，有序玻色子场收缩到一个有限的体积，如一个域。实际上，在所有结晶固体中都存在的马赛克块，必须被视为在Tm处有序的玻色子的域。在每个镶嵌块内，玻色子处于静止模式。随着温度的降低，有序玻色子场的收缩力对每个镶嵌块的压缩越来越大，从而保证了整个固体的内聚力达到Tm。给出了在Tm处有序的玻色子是弹性四极辐射的合理论证。

{"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":"2025-08-01","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

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

Q2 Physics and Astronomy

Physics Open

Pub Date : 2025-08-01 Epub Date: 2025-06-18 DOI: 10.1016/j.physo.2025.100284

Arun Kumar , Nishant Gaur , Aziz Nanthaamornphong

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.

光正交时频空间（OTFS）调制是一种未来的高移动性光无线通信技术。然而，OTFS调制的高峰值平均功率比（PAPR）严重降低了系统性能，特别是在高阶调制格式的情况下。本文提出了一种基于机器学习（ML）的PAPR降低算法，用于不同信道条件下的光学OTFS，如湍流和多径衰落。该方法利用深度学习模型最大化信号处理和抑制峰值功率变化，同时保证信号完整性。仿真结果表明，在互补累积分布函数（CCDF）为10-5的条件下，该方法对256-QAM的PAPR降低了约4 dB和3.8 dB，对64-QAM的PAPR降低了约2.2 dB和1.6 dB，优于传统的PAPR降低方法。功率谱密度（PSD）分析验证了基于ml的技术，如深度神经网络（DNN）、卷积神经网络（CNN）和自动编码器（AE），对于不同信道条件下的256QAM具有频谱效率，可以忽略-1070和-1470的带外辐射。此外，误码率（BER）性能测试表明，在误码率为10-5的情况下，信噪比提高了8.2 dB，信噪比提高了3.9，保证了各种移动场景下的无差错数据传输。此外，将所提出的方法与部分传输方案（PTS）、选择性映射方案（SLM）、音调保留方案（TR）、压缩、裁剪和滤波方案（C&；F）进行了比较。数值结果强调了机器学习在没有PSD和误码率的情况下提高PAPR性能的能力。这一结果对未来的光纤无线网络具有重要意义，在那里必须保持高数据速率并最小化非线性失真。

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引用次数: 0

The mean first passage time as a natural diffusion distance 平均首次通过时间作为自然扩散距离

Q2 Physics and Astronomy

Physics Open

Pub Date : 2025-08-01 Epub Date: 2025-05-06 DOI: 10.1016/j.physo.2025.100271

Maxim J. Goldberg , Seonja Kim

Given an irreducible finite Markov chain, we propose the mean first passage time (MFPT) as a diffusion distance. We motivate this definition by considering a compact Riemannian manifold, and the submanifold resulting from removing the closure of a small ball. The steady-state solution to an associated inhomogeneous heat flow problem on the submanifold is non-negative and can be viewed as having large values at locations which are “far” away from the removed ball. The same function is also shown, at any point, to “count”, via probability, the paths starting at that point which miss the ball. As a third viewpoint, the same function gives the expected value of the first hitting time of the removed ball. The latter interpretation leads to our proposing the MFPT as a diffusion distance for a given finite set of states (samples) and an associated transition matrix. Even if the transition matrix does not arise from heat flow, and may in fact be non-symmetric and non-bistochastic, we note that the MFPT satisfies the triangle inequality. Moreover, various efficient ways to compute the MFPT, and approximations to the MFPT, have been proposed in the literature.

Additionally, we establish a novel connection between certain mean first passage times and the sum of squares of Coifman-Lafon diffusion distances across all scales.

给定一个不可约有限马尔可夫链，我们提出平均首次通过时间作为扩散距离。我们通过考虑紧致黎曼流形和去掉小球闭合后的子流形来激发这个定义。子流形上相关的非均匀热流问题的稳态解是非负的，并且可以被视为在远离被移走的球的位置具有较大的值。同样的函数也显示，在任何点，通过概率“计数”，从该点开始的路径错过了球。作为第三个视点，同样的函数给出被移走的球的第一次击球时间的期望值。后一种解释导致我们提出MFPT作为给定有限状态集（样本）和相关转移矩阵的扩散距离。即使转移矩阵不是由热流产生的，并且实际上可能是非对称和非双随机的，我们注意到MFPT满足三角不等式。此外，文献中还提出了各种计算MFPT的有效方法以及MFPT的近似值。此外，我们建立了一定的平均首次通过时间和Coifman-Lafon扩散距离平方和之间的新联系。

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引用次数: 0

Insights into structural and magnetic properties of manganite perovskite La0.7Ca0.3Mn0.6Co0.4O3 nanoparticles prepared by sol gel auto combustion route 溶胶-凝胶自燃烧法制备锰钙钛矿La0.7Ca0.3Mn0.6Co0.4O3纳米颗粒的结构和磁性研究

Q2 Physics and Astronomy

Physics Open

Pub Date : 2025-08-01 Epub Date: 2025-04-30 DOI: 10.1016/j.physo.2025.100272

R. Sharma , P. Kumar , Anil

The calcium and cobalt co-doped Lanthanum Manganite (La_0.7Ca_0.3Mn_0.6Co_0.4O₃) polycrystalline ceramic was synthesized by sol-gel autocombustion route. The codoping strategy was adopted to study the synergistic effect of incorporating both Ca²⁺ and Mn³⁺ ions in the structural and magnetic properties of LaMnO₃ perovskite for technical applications. The as-prepared sample was characterized by XRD, SEM, FTIR and VSM. XRD study confirmed the formation of a single phase compound with an orthorhombic crystal structure having Pbnm space group. The lattice parameters obtained by reitveld refinements are: a = 5.4406 Å, b = 5.4921 Å and c = 7.7159 Å. The crystallite size was calculated from scherrer method, williamson hall plot, modified scherrer plot, size strain plot, halder wagner plot, reitveld method and compared. The diverse morphology was confirmed by FESEM analysis, while FTIR spectra shows presence of MnO₆ octahedra. Magnetic studies through VSM confirms antiferromagnetic behavior and moderate values of saturation magnetization and coercivity along with higher magnetocrystalline anisotropy, thus suggesting potential application in the field of magnetic sensors like AMR sensors and read heads of hard disk in magnetic data storage applications.

采用溶胶-凝胶自燃烧法制备了钙钴共掺杂锰酸镧（La0.7Ca0.3Mn0.6Co0.4O3）多晶陶瓷。采用共掺杂策略，研究Ca2+和Mn3+离子同时掺入对LaMnO3钙钛矿结构和磁性能的协同效应，为LaMnO3钙钛矿技术应用提供依据。采用XRD、SEM、FTIR和VSM对制备的样品进行了表征。XRD研究证实形成了具有正交晶型结构的具有Pbnm空间基团的单相化合物。通过reitveld细化得到的晶格参数为：a = 5.4406 Å， b = 5.4921 Å， c = 7.7159 Å。采用scherrer法、williamson hall图、修正scherrer图、尺寸应变图、halder wagner图、reitveld法计算晶体尺寸并进行比较。FESEM分析证实了其形态的多样性，FTIR光谱显示了MnO6八面体的存在。通过VSM进行的磁学研究证实了该材料的反铁磁行为，饱和磁化强度和矫顽力适中，磁晶各向异性较高，因此在AMR传感器等磁传感器和硬盘读磁头等磁数据存储领域具有潜在的应用前景。

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引用次数: 0

Effects of applied mechanical stress on the properties of the boundary between circular domains in a cylindrical magnetic wire 外加机械应力对圆柱形磁丝圆畴边界性能的影响

Q2 Physics and Astronomy

Physics Open

Pub Date : 2025-08-01 Epub Date: 2025-05-16 DOI: 10.1016/j.physo.2025.100279

Ján Ziman, Jozef Onufer, Peter Duranka, Mária Kladivová, Peter Vrábel

The paper presents the study of the motion of an individual domain wall in a cylindrical amorphous wire with negative magnetostriction and helical anisotropy induced by the simultaneous application of torsional and tensile mechanical stresses. The non-zero axial component of the magnetization made it possible to monitor the motion of the domain wall by means of suitably wound pick-up coils. Experimental results showed that the wall mobility increases significantly with the application of torsional stress. For a model of a planar domain wall, the calculated eddy currents damping of the wall motion is too strong to explain this increase. Presence of a non-zero axial component of the magnetization can cause the transformation of a planar wall to a deformed wall, axial length of which increases with the applied torsion. It can be expected that the damping of the propagating deformed wall is lower and thus its mobility increases.

本文研究了具有负磁致伸缩和螺旋各向异性的圆柱形非晶态金属丝在扭转和拉伸机械应力同时作用下单个畴壁的运动。磁化的非零轴向分量使得通过适当缠绕的拾取线圈来监测畴壁的运动成为可能。实验结果表明，在扭转应力的作用下，壁面的流动性显著增加。对于平面畴壁面模型，计算出的壁面运动涡流阻尼太大，无法解释这种增加。存在非零的轴向磁化分量可以使平面壁转变为变形壁，其轴向长度随着施加的扭转而增加。可以预期，变形墙体的传播阻尼降低，因而其迁移率增加。

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

Q2 Physics and Astronomy

Physics Open

Pub Date : 2025-08-01 Epub Date: 2025-06-12 DOI: 10.1016/j.physo.2025.100287

Khalil Ur Rehman , Wasfi Shatanawi , Weam G. Alharbi

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.

研究人员一致认为，黑洞的数据是复杂的，本质上是极其非线性的。因此，准确预测相关黑洞的关键特征仍然是一项具有挑战性的任务。目前的工作提供了人工神经网络在选择训练函数的背景下帮助预测天体物理现象，如事件视界和黑洞半径。更具体地说，我们认为史瓦西黑洞是爱因斯坦场方程的最简单解。在神经网络模型的最后一层和第一层分别选择史瓦西半径和质量。使用了两种不同的训练函数，即Levenberg-Marquardt训练算法（LMTA）和缩放共轭梯度训练算法（SCGTA）。我们观察到LMTA的错误率明显更低，这表明它具有更好的拟合和更强的学习能力，可以从黑洞的太阳质量中学习。此外，人工神经网络预测的黑洞半径与实际的史瓦西黑洞半径之间的紧密一致表明，LMTA模型具有有效推广到看不见的黑洞质量的能力。

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引用次数: 0