Physics Open最新文献

{"title":"Ultra-wideband CP metasurface-loaded ring antenna with asymmetric slots and EBG for 5G/satellite applications","authors":"Alamgir Khan, Rehan Ali Khan, Kasim Abdul Jabbar Alsalem, Sami Dhahbi, Bouthaina Dammak, Muneeb Saadat, Muhammad Irfan Memon, Javed Iqbal","doi":"10.1016/j.physo.2026.100447","DOIUrl":"10.1016/j.physo.2026.100447","url":null,"abstract":"<div><div>This paper presents a novel dual-resonance ultra-wideband (UWB) circularly polarized (CP) metasurface-loaded ring antenna, exhibiting <span><math><mrow><mo>|</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>11</mn></mrow></msub><mo>|</mo><mo><</mo><mo>−</mo><mn>10</mn></mrow></math></span> dB over 2.1–2.78 GHz and 3.9–10 GHz (combined FBW <span><math><mrow><mo>≈</mo><mn>130</mn><mtext>%</mtext></mrow></math></span>, compliant with FCC Part 15.517 UWB definition), with asymmetric slot perturbation and an electromagnetic bandgap (EBG) ground for enhanced gain in 5G and satellite communication systems. The antenna is fabricated on an RT/duroid 5880 substrate with relative permittivity <span><math><mrow><msub><mrow><mi>ɛ</mi></mrow><mrow><mi>r</mi></mrow></msub><mo>=</mo><mn>2.2</mn></mrow></math></span>, loss tangent <span><math><mrow><mo>tan</mo><mi>δ</mi><mo>=</mo><mn>0.0009</mn></mrow></math></span>, thickness <span><math><mrow><mi>h</mi><mo>=</mo><mn>1.6</mn><mspace></mspace><mi>mm</mi></mrow></math></span>, and overall dimensions of <span><math><mrow><mn>40</mn><mo>×</mo><mn>40</mn><mspace></mspace><msup><mrow><mi>mm</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math></span>. A 5 × 5 frequency selective surface (FSS)/metasurface grid is employed to improve impedance matching and radiation characteristics. The axial ratio (AR) remains below 3 dB over two distinct circular polarization (CP) bands, 3.5–4.8 GHz and 6.4–8.3 GHz, providing stable dual-band RHCP operation. Outside these frequency ranges, the AR increases beyond 3 dB and the polarization gradually transitions toward elliptical and linear states; hence, the CP behavior is explicitly characterized as dual-band rather than ultra-wideband. In this context, the term UWB refers to the impedance bandwidth, where <span><math><mrow><mo>|</mo><msub><mrow><mi>S</mi></mrow><mrow><mn>11</mn></mrow></msub><mo>|</mo><mo><</mo><mo>−</mo><mn>10</mn></mrow></math></span> dB is achieved over 2.1–2.78 GHz and 3.9–10 GHz, resulting in a combined fractional bandwidth of approximately 130%, consistent with FCC Part 15.517. With the inclusion of the EBG ground plane, the antenna achieves a peak realized gain of 12.5 dBi. The asymmetric slot perturbations of 0.8 mm and 0.6 mm effectively excite orthogonal resonant modes, thereby enhancing circular polarization purity within the two AR bands. Furthermore, the metasurface layer suppresses surface-wave propagation, resulting in an average front-to-back ratio (FBR) exceeding 25 dB and a peak FBR of approximately 30 dB at 8 GHz, while maintaining radiation efficiency greater than 85%. The broadside radiation patterns exhibit cross-polarization levels below <span><math><mrow><mo>−</mo><mn>20</mn></mrow></math></span> dB across the useful impedance bandwidth. Owing to its compact configuration and favorable bandwidth–gain trade-off, the proposed antenna outperforms conventional CP ring antennas and is well suited for sub-6 GHz 5G systems, low-Earth-orbi","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"28 ","pages":"Article 100447"},"PeriodicalIF":2.1,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148642550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From order to chaos: The destabilizing role of time-varying mass in fractional pendulum systems","authors":"Yazen M. Alawaideh,&nbsp;Bashar M. Al-Khamiseh,&nbsp;Hamzah A. Qattous,&nbsp;Tasneem Alayed,&nbsp;Mustafa Bayram","doi":"10.1016/j.physo.2026.100471","DOIUrl":"10.1016/j.physo.2026.100471","url":null,"abstract":"<div><div>This study investigates the nonlinear dynamics of a double pendulum system with exponentially decaying mass by integrating classical mechanics with fractional calculus to capture memory-dependent chaotic behavior. The primary objectives are: (1) to quantify how time-varying mass amplifies chaos relative to fixed-mass systems, and (2) to establish a fractional-order framework that incorporates non-local effects. Using the Caputo fractional derivative and dimensionless Euler–Lagrange equations, we derive governing equations incorporating mass decay μ(τ) = μ₀ e^−γτ (γ = 0.1 s⁻¹). Numerical simulations via fourth-order Runge–Kutta and Adams–Bashforth methods reveal that variable mass intensifies nonlinearity, increasing the maximal Lyapunov exponent from 0.1 s⁻¹ (fixed mass) to 0.41 s⁻¹—a 310% rise. Key results include: angular displacements growing by 44.4% (α: 0.18 → 0.26 rad) and 106.7% (β: 0.15 → 0.31 rad); energy fluctuations reaching 10.41 J (vs. 9.82 J for fixed mass) due to asymmetric torque from mass loss; and Poincaré sections confirming chaotic attractors only in the variable-mass case. The fractional-order model reveals that memory effects synergistically amplify chaos, providing more accurate predictions for engineering systems such as adaptive robotics (e.g., arms with shifting payloads) and aerospace vehicles (e.g., fuel-depleting spacecraft), where our model predicts instability thresholds at critical <span><math><mrow><mover><mi>μ</mi><mo>˙</mo></mover></mrow></math></span> ≈ −0.015 s⁻¹. This work bridges the gap between fractional calculus and real-world variable-mass systems, offering a robust tool for instability prediction and control design.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"28 ","pages":"Article 100471"},"PeriodicalIF":2.1,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148934548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quasi-static mechanical behaviour of rotating saturated porous shafts based on the first-order shear deformation theory","authors":"Hooman Esfandyari,&nbsp;Mohammad Zamani Nejad","doi":"10.1016/j.physo.2026.100459","DOIUrl":"10.1016/j.physo.2026.100459","url":null,"abstract":"<div><div>This study investigates the quasi-static mechanical behaviour of shafts composed of saturated porous materials under angular velocity. The porosity is assumed to be uniform, and the structure is considered to be undrained. Biot's constitutive equations were employed to establish the relationship between stresses and strains. Based on the first-order shear deformation theory (FSDT) and the principle of virtual work, the governing equations of the problem were derived. An analytical solution of the equations was obtained using the eigenvalue and eigenvector method under clamped-clamped boundary conditions. The influence of different parameters such as the porosity coefficient, Skempton's coefficient, and angular velocity on the mechanical behaviour of the shafts was examined. The results indicate that both the porosity coefficient and angular velocity significantly influence the mechanical behaviour of the shafts. It was also observed that the axial stress increase with an increase in Skempton's coefficient. Skempton's coefficient has a negligible effect on the displacements and on the radial, circumferential, and shear stresses.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"28 ","pages":"Article 100459"},"PeriodicalIF":2.1,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148657445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A possible approach for electric charge quantization by a tiny Kerr black hole net","authors":"Tongsheng Xia","doi":"10.1016/j.physo.2026.100469","DOIUrl":"10.1016/j.physo.2026.100469","url":null,"abstract":"<div><div>We introduced a possible electric charge forming mechanism, which includes the quasi normal mode calculations for a Kerr black hole with area of <span><math><mrow><mn>4</mn><mspace></mspace><mi>ln</mi><mspace></mspace><mn>3</mn></mrow></math></span> and spin 2 and the states generation by the preon model. We think the electric charge may exist as energy in the 3 + 1 space time with no need for additional dimension. And we think there might possibly be a tiny Kerr black hole net in our universe, which is sparse for electric charges and will select out the energies corresponding to electric charges as the only possible propagating wave energies. This net may at least be another possible way to have electric charge quantization except confinement, especially when we have to treat it as quantized energy propagating in the 3 + 1 space time. We also showed that electric charge may be the source of a Berry curvature to curve the 3 + 1 space time to form the conventional electromagnetic field. Observation considerations have also been given. Future gravitational wave detections may offer opportunities to check the ideas proposed here. And it shall note that we are still talking about the sub-Planck energy scale in this paper, which is about two to three orders of magnitude less than that of Planck scale Kerr black hole.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"28 ","pages":"Article 100469"},"PeriodicalIF":2.1,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148843619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Surface-potential-controlled intergranular conductance in polycrystalline Bi2Te3 and Sb2Te3 thermoelectric materials: A comparative theoretical study","authors":"Karimberdi Onarkulov,&nbsp;Dilfuza Yusupova,&nbsp;Sarvinoz Sirojiddinova","doi":"10.1016/j.physo.2026.100473","DOIUrl":"10.1016/j.physo.2026.100473","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Grain boundaries in polycrystalline &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Bi&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Te&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;- and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Sb&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Te&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;-based thermoelectric materials may strongly modify charge transport through electrostatic band bending and space-charge-layer formation. In this work, surface-potential-controlled intergranular conductance is analyzed theoretically within the framework of classical semiconductor electrostatics and the grain-boundary barrier model. Calculations were performed at &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;300&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;K&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; for p-type &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Bi&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Te&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Sb&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Te&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; using the dimensionless carrier-imbalance parameters &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;ξ&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;300&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, 1000, and 3000 over the surface-potential interval &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;15&lt;/mn&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Y&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mn&gt;25&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. Both the absolute conductance variation &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;|&lt;/mo&gt;&lt;mi&gt;Δ&lt;/mi&gt;&lt;mi&gt;G&lt;/mi&gt;&lt;mo&gt;|&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and the signed conductance variation &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;Δ&lt;/mi&gt;&lt;mi&gt;G&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; were evaluated.&lt;/div&gt;&lt;div&gt;For negative surface potentials, &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;Δ&lt;/mi&gt;&lt;mi&gt;G&lt;/mi&gt;&lt;mo&gt;&gt;&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; because of hole accumulation near the grain boundary. Moderate positive surface potentials produce &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;Δ&lt;/mi&gt;&lt;mi&gt;G&lt;/mi&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, corresponding to majority-carrier depletion. At larger positive &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Y&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, the increasing electron contribution drives &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;Δ&lt;/mi&gt;&lt;mi&gt;G&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; back toward positive values, producing a second zero crossing of the integrated conductance variation. Increasing &lt;span&gt;&lt;math&gt;&lt;mi&gt;ξ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; enhances the accumulation-side response, deepens the depletion minimum, and shifts this second zero crossing from &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Y&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;≈&lt;/mo&gt;&lt;mn&gt;13.7&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;ξ&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;300&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; to &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Y&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;≈&lt;/mo&gt;&lt;mn&gt;18.7&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;ξ&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;3000&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;.&lt;/div&gt;&lt;div&gt;The dimensionless electrostat","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"28 ","pages":"Article 100473"},"PeriodicalIF":2.1,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148934544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and construction of an electrostatic quadrupole doublet for compact electrostatic accelerators","authors":"M.M. Mansouri Hasanabadi,&nbsp;H.R. Mirzaei,&nbsp;Sh Sanaye Hajari","doi":"10.1016/j.physo.2026.100452","DOIUrl":"10.1016/j.physo.2026.100452","url":null,"abstract":"<div><div>This study presents the design and fabrication of an electrostatic quadrupole (ESQ) lens developed for the future 300 kV upgrade of the laboratory electrostatic accelerator. The structure was modeled and optimized for the higher-voltage configuration of the ES-300 system, while the prototype was constructed and integrated into the existing ES-200 accelerator for initial verification. The geometrical parameters were selected through an optimization process that balanced field quality, mechanical feasibility, and high-voltage stability.</div><div>The ESQ was first analyzed electrically to examine field uniformity and to mitigate edge effects. The introduction of protective and supporting discs effectively reduced the influence of fringe fields and improved field confinement around the aperture region. Subsequently, beam dynamics simulations were performed to evaluate the focusing capability of the designed quadrupole by tracking the beam envelope and its phase-space evolution through the lens system. Finally, the computational model was validated by comparison with theoretical focal-length relations, confirming consistent behavior with the expected electrostatic lens theory. Following the simulation studies, the ESQ doublet was fabricated, installed in the ES-200 accelerator beamline, and experimentally tested under beam conditions to verify its functional focusing behavior.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"28 ","pages":"Article 100452"},"PeriodicalIF":2.1,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148642548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis designs for bandpass filters","authors":"Narmeen Ali Jasem","doi":"10.1016/j.physo.2026.100476","DOIUrl":"10.1016/j.physo.2026.100476","url":null,"abstract":"<div><div>This study presents designs for both broad- and narrow-bandpass filters intended to operate in the mid-infrared spectrum, specifically in the 3000-5000 nm wavelength range. Silicon was used as the substrate, with thin-film material layers featuring high and low refractive indices. The results demonstrate exceptional optical performance, with transmittance and passbands positioned within the desired wavelength range, meeting various application performance requirements.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"28 ","pages":"Article 100476"},"PeriodicalIF":2.1,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148934688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Harmonic passive shimming method for permanent magnet MRI based on target field magnetic constraints","authors":"Xin Liu,&nbsp;Chuangxin Huang,&nbsp;Yanjun Liu,&nbsp;Qi Chen,&nbsp;Qiuliang Wang","doi":"10.1016/j.physo.2026.100455","DOIUrl":"10.1016/j.physo.2026.100455","url":null,"abstract":"<div><div>Harmonic suppression in permanent magnet magnetic resonance imaging (MRI) passive shimming is essential to avoid significant degradation of homogeneity caused by uncorrected harmonic fields, which directly compromises image quality and spatial accuracy. However, traditional passive shimming methods, though capable of partially canceling impurity harmonics, struggle with higher-order harmonic components and fail to simultaneously satisfy the dual objectives of harmonic suppression and improved field homogeneity. In addition, shim thickness in permanent magnet MRI shimming must be constrained to accommodate spatial limitations of the magnet gap while simultaneously achieving material efficiency and system lightweighting. To address these limitations, this paper proposes a harmonic passive shimming method with target magnetic field constraint (HPS-TMFC), which integrates target field constraints into the harmonic optimization model to establish a constraint framework encompassing maximum shim thickness limits, magnetic field inhomogeneity boundaries, and targeted harmonic suppression—thus enhancing control over field uniformity and high-order harmonics. Results demonstrate that the HPS-TMFC achieved a field inhomogeneity of 42.1 ppm (While the initial field inhomogeneity before homogenization is 4367.214 ppm)—representing an approximately 50% improvement over the harmonic method and a 13% enhancement compared to the field method. The above results indicate that the method proposed in this paper can effectively suppress harmonic components while significantly reducing magnetic field non-uniformity, and reduce the consumption of shims.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"28 ","pages":"Article 100455"},"PeriodicalIF":2.1,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148642537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Predicting nonlinear dynamics of thermal energy transport and mathematical analysis of chemically reactive MHD cross stagnation point fluid flow","authors":"Mushtaq K. Abdalrahem,&nbsp;Muavia Mansoor,&nbsp;Muhammad Irfan,&nbsp;Anjali Kizhakke Puthalath,&nbsp;Huma Tayyab,&nbsp;Muhammad Shoaib Anwar,&nbsp;Aamir Nadeem","doi":"10.1016/j.physo.2026.100456","DOIUrl":"10.1016/j.physo.2026.100456","url":null,"abstract":"<div><h3>Background</h3><div>Recent advances elaborate the combining magnetohydrodynamics (MHD) with Cross fluid dynamics presents an innovative range of research that mixtures the non-Newtonian performance of multifaceted fluids with the electromagnetic regulator of fluid flow. This pairing has significant inferences in industries, biomedical, and engineering uses. Furthermore, the non-Newtonian fluids have multiplied considerable importance among scientists because of their noteworthy realism in engineering, biological and technical tools. Additional and further uses of exhausting non-Newtonian fluids are actually established in the current domain, counting slurries, fissile devices, creams, melted polymers, and tissues. Transportation tools elaborate in these flow situations, specifically for precise viscous non-linear fluids, are fetching extra significance to recognize as project necessities acquire additional stringent.</div></div><div><h3>Objective</h3><div>The current study examines the heat transfer via heat sink/source in chemical reactive Cross fluid with magneto stagnation point flow with stretching surface. A Cross fluid depends on shear rate and is generalized Newtonian in nature. The fluid exhibits electrical conductivity when a magnetic fluid is applied. The governing Partial differential equations (PDEs) are converted into Ordinary differential equations (ODEs) by exhausting similarity changes.</div></div><div><h3>Methods</h3><div>Numerical algorithms exist for these modified equations that are determined by using Bvp4c technique. Analysis is conducted on various parameters on temperature, velocity and concentration profiles.</div></div><div><h3>Results</h3><div>The results regarding velocity, temperature and concentration are examined using graphs. Results indicate the velocity decays for magnetic number, whereas intensifies for Weissenberg number. The Prandtl factor diminishes the temperature field. The chemical reaction factor enhances and Lewis number decreases the concentration field.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"28 ","pages":"Article 100456"},"PeriodicalIF":2.1,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148642549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploring the role of hybrid nanoparticle fluids and thermal radiation in atmosphere adjacent to hemisphere","authors":"M.M. Nour,&nbsp;Hossam A. Nabwey,&nbsp;Farhat Imtiaz,&nbsp;Muhammad Ashraf,&nbsp;A.M. Rashad,&nbsp;Abdallah aldurayhim,&nbsp;A.M. Almaslokh,&nbsp;Najla Hamad M. Aldawood","doi":"10.1016/j.physo.2026.100463","DOIUrl":"10.1016/j.physo.2026.100463","url":null,"abstract":"<div><div>The present study addresses the effects of thermal radiation and viscous dissipation on climate change in the presence of hybrid nanoparticle fluid flow around a hemisphere fixed at an angle α to the horizontal. The main aim of this study is to investigate climate change sustainability by considering Al₂O₃–Cu hybrid nanoparticles in the atmosphere as a cooling process. For this purpose, a mathematical model based on nonlinear coupled partial differential equations is formulated, transformed into primitive form using suitable scaling variables, and solved numerically using the finite difference method. Furthermore, the influence of the governing parameters on the velocity, temperature, concentration, skin friction, and mass transfer rate along the hemispherical surface is investigated. The results demonstrate that increasing radiative heat flux reduces fluid velocity due to enhanced thermal radiation effects, while increasing the temperature and mass concentration by promoting thermal energy transport. Moreover, viscous dissipation enhances velocity and temperature profiles through internal heat generation, whereas it decreases the mass concentration due to increased thermal diffusion. The findings provide new insights into the influence of thermal radiation and viscous dissipation on atmospheric heat and mass transport in the presence of hybrid nanoparticles, highlighting their potential for climate-related thermal management applications. The results are presented and discussed using graphs, tables, and contour plots to highlight the physical behaviour of the flow.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"28 ","pages":"Article 100463"},"PeriodicalIF":2.1,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148731342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}