Search Results (916)

Although hydrogen embrittlement mechanisms focus predominantly on the plastic deformation regime, the fundamental effect of interstitial hydrogen on the elastic regime remains elusive. The elastic behavior due to hydrogen is critical because lattice alterations drive microstructural instabilities and macro-failure. This work aims to determine the hydrogen-affected single-crystal elastic constants and anisotropy of 304L stainless steel and link them to dislocation-mediated embrittlement mechanisms. Using in situ neutron diffraction and the Kröner model, this study derived, for the first time, the single-crystal elastic constants ($C_{\mathrm{i}\mathrm{j}}$) of 304L austenitic stainless steel. Hydrogen charging expanded the lattice constant by ~0.7% (from 3.558 $\mathrm{\AA }$ to 3.583 $\mathrm{\AA }$) and selectively increased $C_{11}$ and $C_{12}$ while leaving $C_{44}$ nearly unchanged. Consequently, while bulk polycrystalline Young’s and shear moduli remained invariant, Zener’s anisotropy and Poisson’s ratios increased. Hydrogen reduced the shear modulus of the {111}<110> slip system by ~8.3% and the Peierls–Nabarro stress by approximately 38%. The experimental derivation of single-crystal elastic moduli proved that lattice-scale modifications selectively enhanced volumetric stiffness while lowering the slip-direction shear modulus. Coupled with hydrogen-induced lattice expansion, these findings validate the theoretical volumetric and modulus components of the hydrogen-enhanced localized plasticity mechanism, thereby elucidating its fundamental origin. Full article

Various models exist for predicting the sound absorption coefficient of porous materials, including the capillary model within the Rayleigh model. However, many of these models require an acoustic parameter known as ventilation resistance, which is difficult to determine theoretically for fibrous materials such as wool. This study theoretically estimated the sound absorption coefficient of glass wool using computed tomography (CT) images. Voids within the glass wool were approximated as clearances in two parallel planes. Sound absorption characteristics were theoretically estimated by determining the propagation constant and characteristic impedance within these voids. Furthermore, the theoretical analysis accounted for the tortuosity of the material. During CT image processing, corrections were applied to approximate the actual fiber surface area by accounting for the fiber inclination relative to the direction of sound wave incidence. This correction was determined by approximating the fiber cross-section visible in the CT image as an ellipse and using the resulting ellipticity. A two-microphone impedance measurement tube was used to measure the normal incident sound absorption coefficient. The proposed method provides fundamental insights into the model-based development of sound-absorbing materials and is expected to contribute to cost reduction by eliminating the need for conventional air permeability tests. Full article

Background: Breast cancer (BC) is a biologically heterogeneous disease, with molecular subtypes differing fundamentally in terms of aggressiveness, metabolic behavior, and therapeutic response. Conventional ¹⁸F-FDG PET provides semi-quantitative assessment of glucose-analogue uptake using the standardized uptake value (SUV), whereas dynamic PET with Patlak analysis can estimate kinetic parameters such as the net influx rate constant (K_i) and the volume of distribution (V_d). However, the interpretation of these parameters in breast tissue remains insufficiently defined, and data across BC subtypes are limited. This proof-of-concept study explored the feasibility of deriving preliminary reference ranges for non-pathological breast tissue and describing subtype-specific patterns of kinetic parameters. Methods: Six breast cancer patients affected by Luminal (n = 4) or triple negative BC (TNBC, n = 3) and six control patients underwent dynamic ¹⁸F-FDG PET/CT. Patlak kinetic analysis generated parametric K_i and V_d maps. Lesion-level first-order radiomics features were extracted for each breast lesion. Non-lesional breast volumes (contralateral breast and breast excluding disease) were characterized to derive exploratory physiological reference ranges. Results: In control whole-breast tissue, median values were SUV 0.28 g/mL, K_i 0.056 mL/min/100 mL, and V_d ~9%. Non-lesional breast tissue in BC remained statistically concordant with controls. Lesion analysis suggested a possible metabolic gradient across subtypes: Luminal B with low proliferation activity exhibited lowest K_i (0.34 mL/min/100 mL), and highest V_d (~39%); Luminal A showed intermediate K_i (1.93 mL/min/100 mL) and V_d (~27%) values; TNBC showed higher K_i (3.02 mL/min/100 mL) with a greater proportion of zero-valued V_d voxels. Conclusions: This exploratory study suggests that parametric maps may be feasible for describing physiological breast tissue kinetic ranges and for exploring subtype-associated metabolic differences in BC. The observed K_i and V_d patterns may reflect differences in glucose phosphorylation and tracer distribution across tumor phenotypes, but the biological meaning of Patlak-derived parameters requires further methodological and histopathological validation. Larger prospective studies are needed before these parameters can be considered clinically applicable imaging biomarkers. Full article

The transfer-matrix method is employed to investigate a spin-1/2 Ising chain under open and periodic boundary conditions. It is demonstrated that finite-size Ising chains with antiferromagnetic coupling may exhibit significantly distinct magnetic behavior under open and periodic boundary conditions. While the open Ising chains display intriguing magnetic features regardless of the system size, mainly due to a specific contribution of boundary spins, the magnetic behavior of closed Ising chains depends basically on the number of spins. The closed Ising chains with an odd number of spins are subject to a geometric spin frustration leading to an additional plateau in the magnetization curve, which is naturally absent in the closed Ising chains with an even number of spins. Despite different microscopic origins, the magnetization curves of open and closed Ising chains with an odd number of spins exhibit an identical intermediate plateau, with only small quantitative differences appearing at moderate temperatures, which means that a geometric spin frustration of odd-membered rings is somewhat similar to the effect of open boundaries. The magnetization curves of the open Ising chains with an even number of spins differ drastically from those of the closed Ising chains due to the presence of an additional intermediate magnetization plateau. Furthermore, the initial susceptibility, inverse initial susceptibility, and susceptibility–temperature product are examined in detail as functions of temperature. These magnetic response functions demonstrate that the Curie constant and Weiss temperature represent fundamental characteristics of the magnetic system that are independent of the choice of boundary conditions. Full article

Changes in wood moisture content significantly affect its dimensions, mechanical properties, and vibrational characteristics. Thermal treatment is one of the most convenient approaches for improving the moisture resistance of wood; however, the effects of treatment conditions on moisture content and vibrational characteristics after short-term cyclic moisture absorption have not been clearly investigated. In this study, dry thermal treatment at 160–220 °C for three different durations was applied to Japanese cedar specimens. Higher thermal treatment temperatures and longer treatment times decreased the equilibrium moisture content (EMC). The fundamental resonant frequency of the free–free flexural vibration (f₁) increased with increasing treatment temperature, whereas it decreased over a longer duration. All specimens were subjected to three cycles of moisture change tests from 60%RH to 98%RH at 40 °C to track the change in moisture content, f₁ and its loss tangent (tanδ). The specimens treated at higher temperatures maintained a lower moisture content and higher f₁. Under most treatment conditions, the moisture content at 98%RH increased from the first to the second cycle and remained constant in the third cycle. On the other hand, the resonant frequency at 98%RH remained unchanged from the first to the second cycle but increased in the third cycle. This indicates that the moisture surface became saturated in the second cycle, and moisture diffusion from the surface to the inside of the specimen increased with the number of cycles. Near-infrared absorption revealed that high-temperature treatment caused thermal decomposition of hemicellulose and an increase in apparent crystallinity due to a reduction in the amorphous region of cellulose. These changes enhance the hydrophobicity of the cell wall, contributing to moisture resistance and vibrational stability. Full article

Continouous unmanned aerial vehicle (UAV) missions are fundamentally limited by Lithium-Polymer (LiPo) battery endurance under intermittent and power-constrained renewable energy conditions. This paper proposes an integrated energy management and charging framework for a photovoltaic (PV)-powered mobile station equipped with a hybrid energy storage system (HESS) and an automated battery replacement (ABR) mechanism. A lexicographic priority-based allocator sequentially serves ABR actuation, multi-slot LiPo charging, and Brushless DC (BLDC) propulsion, while the HESS compensates for PV intermittency. At the charging level, a constraint-aware constant current–constant voltage (CC–CV) strategy is enhanced by an adaptive neuro-fuzzy inference system (ANFIS) trained on optimization-derived labels using battery temperature and its rate of change, thus enabling anticipatory thermal current derating with smooth, discontinuity-free control action. Anti-windup proportional–integral (PI) regulation and bumpless mode transfer ensure stable CC-to-CV transitions. An event-triggered emergency mode accelerates battery readiness via a max-first selection policy. Comparative simulations against a PSO/DE-optimized PID benchmark over a full diurnal PV cycle demonstrate that the ANFIS controller reduces the CC-mode current tracking root-mean-square error (RMSE) by up to 96.9%, delivers higher charge throughput, and lowers battery degradation proxies, including SOC-weighted thermal dose and equivalent full cycles (EFC). The proposed framework reliably sustains continuous charge–swap–recharge logistics under fluctuating renewable generation. Full article

The article presents an original approach to automatic musical key detection, combining Constant-Q Transform (CQT) analysis with the Triple Composite Signature of Fifths (TCSF). The method’s novelty lies primarily in the construction of the Signature of Fifths (SF), which is grounded in fundamental principles of music theory and builds on earlier SF-based studies. The proposed approach aims to preserve the algorithmic simplicity typical of SF approaches while strengthening their key advantages. In addition, the method reflects the analytical approach of experienced musicians by assigning greater importance to the initial and final sections of a piece. The use of CQT enables efficient audio analysis and offers a practical compromise between frequency resolution and alignment with the pitch-class representation. Experiments conducted on Franz Schubert’s songs from the Winterreise song cycle and Frédéric Chopin’s Preludes, Op. 28, confirm the effectiveness of the proposed algorithm, achieving 87.5% and 79.2% key-detection accuracy, respectively. The obtained results demonstrate that the proposed method is competitive with tonal profile-based key-detection approaches. Full article

Despite advances in reactor-based process intensification, the influence of hydrodynamic conditions on PFAS removal remains poorly understood. In particular, rotating bed reactors (RBRs), which are designed to enhance mass transfer, have not been systematically evaluated for PFAS removal or compared with conventional batch and fixed-bed column systems. This lack of comparative understanding limits the ability to assess their practical relevance for PFAS remediation. In this study, PFAS removal was investigated under intensified hydrodynamic conditions using an RBR and compared with batch and small-scale column systems with special focus on short-chain PFAS compounds. The RBR significantly enhanced adsorption kinetics, with pseudo-first-order rate constants increasing by 3 to 16-fold across PFAS, particularly for short-chain PFAS. For instance, PFBA exhibited near-complete removal within 12 h in the RBR, whereas only ~50% removal was achieved in batch conditions. However, faster kinetics did not translate into superior long-term breakthrough performance compared to the column treatment system. After 50 treatment cycles using ion exchange resin, PFBA reached approximately 40% C/C₀ in the RBR, while the column system maintained C/C₀ below 5%; similar trends were observed for PFPeA (15% vs. ~0.5%) and PFHxA (6.2% vs. ~0.2%). These findings reveal a fundamental trade-off between kinetic intensification and long-term treatment performance. The results highlight distinct design roles, with RBR systems enabling rapid and intensified treatment (e.g., staged or parallel configurations), while conventional column systems perform better for continuous operation and compliance control in PFAS remediation. Full article

The Dirac operator links harmonic analysis, physics and hypercomplex signal representations. However, most Dirac-based imaging methods remain integer order and lack spectral adaptability. In this paper, we propose a novel fractional Dirac framework for edge detection. Some fundamental properties are obtained, including square factorization, Liouville-type properties, and uncertainty principles with sharpened constants in a limiting case. Then, a numerically stable discrete realization is developed based on the quaternion Fourier transform. This realization yields an edge detector for both grayscale and RGB images. Experiments on benchmark datasets show that the proposed method produces coherent contours and competitive boundary-detection performance compared with classical gradient methods and recent transform-based detectors. Full article

Hydraulic fracturing is the primary technology for extracting unconventional oil and gas resources. Rock apparent fracture toughness is the most critical parameter in hydraulic fracturing processes. Rock apparent fracture toughness exhibits characteristics distinct from those of metallic materials, particularly as field-estimated values of rock apparent fracture toughness in hydraulic fracturing exceed laboratory-measured values by 1–2 orders of magnitude. Existing interpretation models assume a constant stress distribution in the fracture process zone (FPZ), which contradicts the softening behavior of rock. To address this gap, and based on the assumption of a power-law softening stress distribution in the FPZ of quasi-brittle rock, we develop a mode I apparent fracture toughness model for rock under far-field tensile and compressive stress configurations. This model considers both the softening characteristics of rock and the fluid lag effect. A comparative analysis was conducted on the differences in rock apparent fracture toughness between far-field compressive stress and tensile stress configurations. The results reveal that the difference in configuration between far-field compressive stress and tensile stress constitutes the fundamental reason for the order-of-magnitude discrepancy between the rock apparent fracture toughness estimated from hydraulic fracturing field tests and that measured in laboratory experiments. The influence of the ratio of in situ stress to tensile strength, the ratio of FPZ length to fracture length, the ratio of fluid lag zone length to fracture length, and stress distribution within the FPZ on rock apparent fracture toughness was analyzed, and these factors are found to have decisive effects on the rock apparent fracture toughness. Additionally, the size effect on rock apparent fracture toughness was discussed. This research contributes to more precise hydraulic fracturing parameter design. Full article

In response to the current limitation where conventional constant volume combustion apparatuses are generally confined to pressure ratings of 5–20 MPa, insufficient for the demands of ultra-high-pressure combustion fundamental research, this study designs and verifies a high-pressure-resistant constant volume combustion apparatus with a rated working pressure of 250 MPa. The strength design and safety factor calculation for the combustion chamber main body were conducted based on the Lame thick-walled cylinder elastic theory. A finite element numerical simulation method was systematically employed to perform static analysis, transient impact response analysis, and high-cycle fatigue-life assessment of the key components of the apparatus. The results indicate that under a 250 MPa design internal pressure load, the maximum circumferential stress at the inner wall of the combustion chamber main body is 328.0 MPa, with a safety factor greater than 1.5, complying with relevant safety codes for high-pressure vessels. Under transient loading simulating combustion impact, the maximum equivalent stress of all structural components is below the material yield strength, with a maximum elastic deformation of less than 0.06 mm, demonstrating excellent structural stiffness and impact resistance. Fatigue assessment with a design-life target of 1.0 × 10⁶ pressure cycles shows that the cumulative damage values for all components are significantly less than 1.0, meeting the reliability requirements for long-term cyclic service. This apparatus integrates functional modules such as high-pressure precision gas mixing, high-energy reliable ignition, high-speed transient parameter acquisition, and safe product collection, providing a stable, controllable, and safe experimental platform for in-depth research on the combustion mechanisms of gaseous fuels under ultra-high-pressure conditions. Full article

The integration density of photonic integrated circuits is fundamentally limited by evanescent field overlap and subsequent inter-channel crosstalk. Layered transition metal dichalcogenides (TMDCs) bypass these confinement constraints through intrinsic optical birefringence and high refractive indices. Here, we report the near-infrared optical constants and waveguide dispersion of molybdenum diselenide (MoSe₂). Ellipsometry performed on centimeter-scale crystals yields an in-plane refractive index of 4.1–4.7 over 1000–2000 nm, with an extinction coefficient close to the sensitivity limit of the fit away from strong excitonic resonances. To validate the anisotropic dielectric tensor at the device scale, scattering-type scanning near-field optical microscopy (s-SNOM) was utilized to map the propagation of transverse-magnetic modes in 235 nm thick exfoliated flakes. Spatial Fourier analysis of the edge-scattered near-field interference yields effective mode indices that precisely match the modeled dispersion. Using the verified dielectric tensor, finite-element simulations demonstrate that single-mode MoSe₂ waveguides optically outperform equivalent tungsten disulfide (WS₂) benchmarks. The enhanced evanescent field suppression in the claddings of MoSe₂ waveguide increases the coupling length by a factor of 3.5, reducing the required routing pitch and enabling a 12.5% direct increase in on-chip integration density. The results identify MoSe₂ as a high-index anisotropic platform for compact waveguiding in the near-infrared. Full article

The shear strength–suction (here suction induced from unsaturation) relationship is inherently challenging, yet this difficulty is compounded for cemented crushable sands, whose behavior fundamentally diverges from classical clay-centric theories. This paper presents an innovative teaching case study focusing on colloidal-silica-cemented calcareous sand, based on direct shear tests across a full saturation range (0–100%). Our experimental findings reveal two unconventional characteristics that challenge textbook models: (1) suction strength exhibits a positive dependency on normal stress—an inverse trend to conventional expectations; and (2) strength near desiccation drops below saturated values, contradicting the monotonic increasing function typically observed in clays. A review of 20 existing models confirms that none of them can simultaneously capture both features, highlighting a clear gap in both theory and instruction. To address this gap pedagogically, the core novelty of this work lies in the development of a classroom-friendly predictive model that introduces two physical innovations: first, it incorporates normal-stress-dependent suction strength by modifying capillary condensation probability—departing from constant-angle assumptions; second, it accounts for desiccation-induced strength deterioration through a gel crack size effect, which is absent in conventional unsaturated strength formulations. The model retains clear physical interpretability and demonstrates strong agreement with experimental data. By integrating unconventional behavior, model limitations, and novel physically inspired formulations into a coherent case study, this work equips students not only to recognize deviations from classical unsaturated strength theory but also to construct their own mechanistic models in geotechnical engineering education. Full article

Punching is a fundamental and extensively employed process in the field of cold forming, prized for its operational simplicity, high performance, and ability to produce components of superior quality. However, the process is inherently complex, as the selection of optimal punching parameters remains a challenging endeavor. Achieving a high-quality punched product is critically dependent on the precise and validated choice of these parameters, which directly influence the mechanical and geometrical integrity of the final component. In this study, the shear zone height, a key indicator of punched part quality, is systematically investigated. The finite element method (FEM), integrated with the Johnson-Cook material model, is employed to simulate and analyze the influence of various punching parameters on the shear zone height, with particular emphasis on the effect of different punch shaft shapes. The Johnson-Cook model, renowned for its accuracy in capturing material behavior under high strain rates and temperatures, enables a robust and reliable simulation framework. The results of this investigation reveal that punch tools featuring a pointed shaft shape exhibit an almost constant distribution of shear zone height across a range of punching parameters. This consistency suggests that such designs are less sensitive to parameter variations, thereby offering a more stable and predictable performance. Consequently, the pointed punch shape is identified as the optimal configuration for achieving superior punched part quality, minimizing defects, and enhancing process reliability. This work contributes to the advancement of cold forming technology by providing insights into the relationship between punch geometry and shear zone characteristics, ultimately facilitating the selection of punching parameters for improved product quality and process efficiency. Full article

This study investigated the optoelectronic synaptic properties of amorphous gallium oxide (GaO_x) thin films for low-power physical reservoir computing (PRC) applications. The fabricated devices were irradiated with time series UV-C light to characterize the paired pulse facilitation (PPF) index, a fundamental synaptic property governed by transient photocurrent dynamics. Furthermore, the short-term memory (STM) capacity and parity check (PC) nonlinearity were quantitatively evaluated as essential PRC performance metrics, alongside a practical demonstration using a handwritten digit recognition task. The experimental results revealed a high PPF index when the width and interval of the input light pulses were comparable to or shorter than the inherent photocurrent time constants of the device. Although the evaluated nonlinearity was lower than that of conventional optoelectronic artificial synapses based on other semiconductor materials, the GaO_x device exhibited a comparable short-term memory capacity. Consequently, the reservoir layer achieved a high classification accuracy of approximately 90% in the handwritten digit recognition task. As these performance metrics were higher than those of the annealed sample, the device without annealing proved to be more suitable for PRC applications. These findings indicate that the amorphous GaO_x thin film device holds significant potential to serve as a robust, UV-C-responsive edge artificial intelligence (AI) sensor in harsh environments, such as outer space. Full article