Press shaving is a shearing method using a punch and die, in which reducing the shaving allowance increases the burnished surface area. The objective of this study was to clarify the changes in the equivalent strain distribution as the punch stroke increased during press shaving. The deformation of the sheet material during the shaving process was observed in situ, and the equivalent strain distribution was determined using digital image correlation. The results indicated that regions of high equivalent strain developed and expanded during processing. Additionally, increasing the shaving allowance led to expansion of the high-strain region of the specimen on the die. During the initial stage when only the punch cutting edge penetrated the specimen with a small shaving allowance, the equivalent strain in the specimen on the die did not increase, whereas localized strain increased near the punch side. The deformation was confined to a limited region under the punch. By contrast, a larger shaving allowance produced a wider region of elevated strain between the punch cutting edge and die cutting edge. Moreover, the equivalent strain of the specimen between cutting edges increased during crack propagation from the punch cutting edge. These results clarified the influence of shaving allowance on strain distribution in press shaving.
Nickel is an important material for the development of a hydrogen society. While it leads to excellent performance against hydrogen in alloys, the hydrogen sensitivity increases for the pure material. A lot of research has been conducted so far, calculating the dislocation density by tensile or rolling strain of nickel with hydrogen, and changes in crystal orientation have been confirmed using EBSD. These research findings do not definitively determine the effects of hydrogen, as multiple complex factors are intertwined, making it challenging to investigate specific impacts. This research focused on finding the underlying causes of hydrogen embrittlement by consistently analyzing the effects of hydrogen on dislocations. Nickel specimens after hydrogen gas exposure were subjected to tensile testing, and the dislocation density variation in response to tensile strain was investigated using X-ray diffraction. The hydrogen-charged specimens exhibited an increase in yield strength and a decrease in fracture strain during tensile testing. The dislocation density was higher in the hydrogen-charged specimens compared to the uncharged ones, with the rate of increase diminishing as strain progressed. In addition, the appearance of brittle fracture was confirmed on the fracture surfaces, further confirming the influence of hydrogen.
Mechanical nonreciprocity is outside the scope of conventional symmetry in mechanical and physical systems, enabling a range of engineering applications such as asymmetric transmission, energy conversion, impact protection, and biological manipulation in unprecedented ways. This study numerically investigates the asymmetric inhomogeneous deformation of a nonreciprocal gel under cylindrical indentation. A nonreciprocal gel exhibits significant mechanical nonreciprocity owing to the buckling of the nanosheets embedded within the hydrogel matrix and is distinguished by three key characteristics: anisotropy, tension-compression asymmetry (TCA), and nonlinearity. To study the effects of these three factors systematically and quantitatively, finite element analysis of the cylindrical indentation is conducted using non-TCA (nTCA), TCA, and TCA-nonlinear (TCAn) models. The results reveal that the nTCA model shows almost no asymmetric deformation, whereas the TCA and TCAn models exhibit significant asymmetric deformation and show good quantitative agreement with the experimental results. The interaction between the TCA factor and the interfacial slip between the cylinder and the gel is essential for asymmetric inhomogeneous deformation. The frictionless condition is also validated in comparison with the previously reported experimental data. The slight difference in results between the TCA and TCAn models is attributed to strain relaxation in the unbuckled direction due to interfacial slip.
For automotive body structure, to improve fuel and electricity consumption, weight reduction is necessary, and crash safety is also required. Therefore, the strength of some steel sheets for automotive structure is increased to the order of 1 GPa. For high velocity tensile tests of such steel sheets, ISO 26203-1 was established in 2010, and in Japan JIS Z 2205:2019 was also established for high velocity tensile tests of sheets using the split Hopkinson bar method. In this way, experimental results have been accumulated for the steel sheets, and they have been used in structural design, significantly reducing the number of fatalities from traffic accidents. However, for the mechanical properties of resistance spot welded joint which is widely used to join these steel sheets, tensile shear test and cross tension test methods have been standardized in quasi-static tensile loading only. No standard describes the test methods in dynamic tensile loading. So, the dynamic tests require the development of original experimental methods. If there are changes to the specimen shape, it is necessary to verify whether the quasistatic joint strengths are compatible with standardized quasi-static tensile joint strengths. However, as far as the present author knows, there is not any research that has focused on this point. In this study, for resistance spot welded joint made of 980 MPa grade electric arc furnace steel sheet, the quasi-static joint strengths of specimens developed for dynamic loading were examined the difference with the strengths obtained with specimens established by standards, JIS Z 3136:1999 and 3137:1999. They were found that sufficient compatibility was achieved, respectively.
Accurate severity assessment during emergency medical service (EMS) calls is essential for timely dispatch and efficient resource allocation. This study investigates whether callers' voice acoustics can provide a low-latency, acoustics-only decision-support signal that operates in parallel with protocol-guided triage in operational call centers. Severity labels were defined using post-transport clinical severity at the first medical examination after transport (Japanese sh & omacr;by & omacr; teido) as recorded in EMS outcome records. This label should be interpreted as a clinically meaningful downstream outcome surrogate rather than a direct observation of urgency at call time. Accordingly, because this outcome-based label may not fully align with call-time dispatch priority, the proposed score is positioned as a protocol-parallel auxiliary alert cue rather than a replacement for protocol triage or a direct model of dispatcher-perceived urgency. Using anonymized Japanese EMS call recordings from the Tokyo Fire Department, we analyzed a balanced subset of 204 calls (102 serious, 102 minor) after excluding moderate cases. We extracted call-level acoustic descriptors (F0 statistics, MFCCs, Mel-band energies, spectral measures, and voice-quality features) and conducted Mann-Whitney U tests with false discovery rate (FDR) correction, revealing systematic differences, particularly in pitch variability and spectral energy patterns. Robustness was evaluated using a waveform-level Wiener-filtering baseline and systematic data augmentation (pitch shifting, gain perturbation, and additive noise) under stratified cross-validation. Logistic regression, RBF-kernel support vector machine, and random forest models were assessed using area under the ROC curve (AUC) and recall-focused operating points selected to satisfy a target recall for serious cases (Recall_serious) of at least 0.90. Within the present internal cross-validation setting, full augmentation yielded the best discrimination, whereas Wiener filtering provided limited and model-dependent gains. The best configuration within the present dataset (random forest with full augmentation) achieved AUC = 0.93 and Recall_serious = 0.933. These results suggest the potential feasibility of integrating an acoustics-only severity score as a complementary alert signal, while highlighting limitations when vocal arousal cues are weak or caller speech is sparse.
We have developed an automatic piping layout design system for piping and equipment using AI to rationalize nuclear plant costs, shorten schedules, improve safety and reliability, and maintain design technology. The system automatically generates short, appropriate piping routes, taking into account the reactor building and equipment layout. In addition, a method was developed to design piping routes within a limited region. This allows piping to be automatically designed while strictly adhering to radiation control classification and nuclear safety classification according to the piping attributes. Additionally, attributes can be assigned to structures, and differences in obstacles such as equipment, reactor building frames, and access paths can be recognized. Moreover, the system avoids prohibited areas such as inspection spaces, passages, electrical rooms, and safety equipment zones. Furthermore, the system can design piping considering walls, floors, ceilings, and beams, and functions for vertical wall penetration and wall approach have been developed. As described above, the system is equipped with diverse functions that enable compliance with multiple design rules. This system can automatically design several thousand piping in one day after setting design conditions, enabling cost and schedule rationalization. These technologies were realized through the integration of AI and optimization algorithms, as well as the strong promotion of digitalization. This system significantly contributes to enhancing the design efficiency and safety of nuclear power plants, ensuring reliability and reducing costs. This study demonstrates the effectiveness of applying automatic design technology to nuclear power plants.
Structural singularities in catenary-pantograph systems, such as connectors and splicers, induce transient responses that accelerate local degradation and maintenance. While recent analytical work has clarified the fundamental transient-wave mechanism at structural singularities, the local mechanical response around a singularity in a practically relevant setting remains insufficiently understood. We therefore conduct complementary theoretical and full-scale experimental investigations of these transients for a pantograph traversing a local structural singularity. We formulate a tractable analytical model, namely a simply supported, tensioned beam coupled to a local mass-spring singularity and subjected to a moving load. Closed-form expressions clarify the wave interactions at the singularity and the parameter dependence of contact wire strain at the singularity. Full-scale experiments using actual equipment validate the proposed model over a wide range of operating conditions, with various singularity locations, and train speeds. The proposed model faithfully captures the qualitative behavior within the time interval of engineering interest and reproduces the maximum and minimum strains with quantitative accuracy up to 200 km/h. Mechanistically, the minimum strain is shown to originate from waves radiated when the load starts to move, leading to a monotonic increase with both singularity mass and train speed, whereas the maximum strain exhibits a non-monotonic dependence arising from interference between local singularity motion and incoming waves. These results provide useful insights for fitting design and construction guidelines.
Since lead has been banned in bronze alloys due to its toxicity to human health, an alternative solid lubricant is urgently required to replace it. Previous studies have indicated that Cu5FeS4 could be used in bronze alloys to enhance their lubricating properties. Specifically, for bronze powder metallurgy, Cu5FeS4 exhibits beneficial lubricating effects during compaction, allowing the bronze powder to be smoothly compacted and demolded without additional lubricants. In this study, mixtures of bronze powders with different particle sizes and Cu5FeS4 were investigated to evaluate their effects on bronze compacts during both the compaction and sintering processes. Experimental results showed that the demolding force decreased to approximately 50%-70% of pure bronze powder depending on the addition of Cu5FeS4 and the particle size of the bronze powder. These findings demonstrate that Cu5FeS4 not only reduces the friction coefficient after sintering but also effectively lowers frictional resistance during the compaction process.
Flexible and mechanically compliant power sources are increasingly required for wearable electronics and soft robotic systems, where stable operation under bending and other deformations must be combined with safety, comfort, and long-term durability. Although hydrogel-based electrolytes are attractive because of their softness, ionic conductivity, and low flammability, practical implementation remains limited by weak gel-gel and gel-electrode interfaces, deformation-sensitive electrical output, and insufficient environmental stability caused by drying, freezing, and swelling. In this study, we propose a thin, highly flexible battery based on an integrated five-layer acrylamide-gel cell composed of a high-salinity gel, an anion-selective gel, a low-salinity gel, a cation-selective gel, and a second high-salinity gel. These layers are monolithically bonded using gel prepolymer solutions to suppress interfacial failure and structural collapse while maintaining ionic conductivity. Flexible carbon fabric electrodes are implemented at both ends, and the entire device is encapsulated with a thin silicone elastomer to maintain mechanical compliance while providing packaging protection. In addition, glycerol is introduced into the gels to form an organohydrogel, thereby improving resistance to dehydration and enhancing environmental robustness for long-term use. The proposed design also enables lateral series integration of cells, allowing system voltage to be increased without increasing device thickness. Experimental evaluations focusing on long-term stability, discharge behavior, and flexibility are performed to examine the feasibility of the proposed device for thin, soft, and wearable power applications.
In this paper, we report a low-cost printing process for poly(3,4-dioxythiophene) (PEDOT): polystyrene sulfonate (PSS)-based all-organic microelectrodes suitable for in vitro neural stimulation and recording. Conventional microelectrode arrays (MEAs) are primarily composed of expensive metals and have been fabricated through high-cost and complex lithography processes, which limits their application to neuroscience experiments. Here, we present a method that combines a printing-based fabrication method for microelectrodes using a PEDOT:PSS composite ink, the formation of an insulating layer having a single-cell-sized sensing opening, and the improvement of cell-electrode contact by adding a PEDOT:PSS/poly(ethylene glycol) diacrylate (PEGDA) composite conductive hydrogel to the opening. Through a simple microfabrication process using cheap and easily obtainable inks, cost reduction and improved accessibility of MEAs are expected. Microscopic observation revealed that the fabricated microelectrodes possess transparency suitable for the observation of cells. The biocompatibility of the device was suggested by a Live/Dead assay of cultured cells. Also, cyclic voltammetry revealed that it has a large electric double-layer capacitance of 0.842 F/cm(2). This is important for preventing electrolysis accompanied by cytotoxicity during electrical neural stimulation. Furthermore, this electrode exhibited a sufficiently low electrical impedance of 0.300 Omega & centerdot;cm(2), making it suitable for neural recording with a high signal-to-noise ratio, and it successfully acquired model electrical waveforms in physiological saline. The localized opening required hydrophilic treatment to demonstrate performance; however, by adding the gel, these excellent performances were achieved without hydrophilic treatment, and they did not significantly degrade even after a washing process. These results indicate that easily fabricable and low-cost printed all-organic microelectrodes can be utilized for neural stimulation and recording, and we believe that the application of MEAs can be expanded into various neuroscience research.
