Accurate identification of hysteretic restoring‑force parameters in civil structures usually requires displacement or strain measurements that are rarely available in field monitoring. This study proposes a sequential Bayesian updating framework that estimates confidence intervals for seven hysteresis parameters and four algorithmic hyperparameters (11 variables in total) solely from absolute acceleration records. Initial particle populations are generated by Evolutionary Computation, and the posterior distribution is progressively refined with a Sequential Monte Carlo sampler in which a kernel‑density‑estimated likelihood accommodates multi‑modal residuals. The approach eliminates manual tuning of algorithmic hyper‑parameters by learning the KDE (Kernel Density Estimation) bandwidth and PSO (Particle Swarm Optimization) coefficients simultaneously with the physical parameters. Numerical verification using a single‑degree‑of‑freedom system with a bilinear skeleton curve lacking point symmetry about the origin demonstrates that, after assimilating 100 % of the simulated earthquake data, the posterior standard deviations shrink by more than 70 % while the 95 % confidence intervals capture the true values of all variables. Throughout the three data‑assimilation stages, the effective sample size remains above 90 %, indicating negligible particle degeneracy.

The rapid proliferation of unmanned aerial vehicles (drones) has made ensuring safety through non-cooperative collision avoidance an urgent priority. Acoustic sensing offers a lightweight solution; however, detecting approaching rotorcraft, such as helicopters, remains challenging due to the high levels of drone self-noise. To address this challenge, this study proposes a robust sound source detection and direction estimation method focusing on the amplitude modulation (AM) characteristics inherent in rotorcraft noise. First, utilizing the cyclostationary nature of rotorcraft noise, we adopted the Fast-Spectral Correlation (Fast-SC) algorithm. By calculating the Enhanced Envelope Spectrum (EES), we successfully separated helicopter signals, which exhibit specific low-frequency modulation, from drone noise containing high-frequency modulation. Second, we developed a direction estimation technique integrating this AM analysis with a fixed delay-and-sum beamformer (DSBF) using a linear microphone array. By scanning the beam and evaluating the spatial distribution of AM intensity, the system can accurately estimate the direction of the approaching helicopter. Furthermore, we conducted a comprehensive investigation to optimize the microphone array configuration, specifically analyzing the effects of the number of microphone elements and their spacing on AM directional characteristics. The results from numerical simulations and field verification experiments showed high consistency. Consequently, suitable design parameters maximizing detection performance were identified, demonstrating the applicability of the system to practical collision avoidance.

In recent years, personal mobility vehicles (PMVs) have attracted attention as a new means of transportation for older adults. In general, PMVs have the advantage of being compact and maneuverable, but both the rider and vehicle have a high center of gravity, which may cause the rider to lose their balance. In this study, we investigated the dynamic characteristics of PMV riders during sudden turns and clarified differences in behavior with respect to age, as well as how these differences vary depending on driving conditions, through vehicle experiments. Measurements revealed that the rider's center of gravity (COG) tended to shift toward the inside during turns. Additionally, through the analysis of the time series changes in joint moments, it was observed that younger individuals tend to apply force to upper-body joints such as the shoulders, elbows, and wrists, while older individuals tend to concentrate force on lower-body joints such as the knees and hips to control posture. Furthermore, older riders were found to apply force in advance in a direction opposing motion centered on the hip joint, revealing the characteristics of their posture control strategy.

In ball-mill grinding, the internal state of comminution is difficult to monitor because the mill is enclosed, and stop timing often depends on operator experience. This study investigates the analytical conditions for unsupervised discrimination of particle size using radiated sound from an operating laboratory-scale ball mill. The radiated sound pressure was measured with four microphones placed around the mill wall, and frequency spectra were obtained. The obtained spectra were utilized as input features of a one-dimensional self-organizing map (SOM) to cluster acoustic patterns without prior training data on particle-size distributions. To assign a physical scale to the SOM units, they were rearranged according to the average overall value (OA) of the spectrum classified into each unit. The discrimination performance was evaluated using the mean unit index for six particle sizes ranging from 0.5 to 10 mm under identical operating conditions. Furthermore, the effects of the analyzed frequency band and FFT time-window length were investigated. The high-frequency band reduced the variance of unit indices and improved the separability among particle sizes, whereas a 0.2 s window with 50% overlap achieved the best balance between maintaining separability and securing a sufficient number of spectra. These results provide practical guidelines for applying SOM-based unsupervised monitoring to in-situ estimation of grinding progress.

Active magnetic bearings (AMBs) have generally been implemented on machines on rigid bases. However, when integrated into ships or vehicles, base excitation poses a significant challenge due to the inherently low stiffness of AMB systems. This study aims to reduce the vibration response of levitated rotors subjected to pitching base excitation. The response characteristics of both non-rotating and rotating rotors connected via spring couplings were experimentally investigated under vertical and pitching excitations. A feedforward control approach using accelerometer signals was implemented to estimate and cancel inertial forces arising from base motion. Under vertical harmonic excitation (10 Hz, 6.3 m/s²), the proposed method reduced rotor vibration amplitudes by more than 64%, successfully preventing contact with the touch-down bearings. Under pitching excitation (10 Hz, 15 rad/s²), which induced vibrations in both the radial and axial directions, the feedforward controller effectively reduced vibrations in both directions.

This paper investigates structural improvements for a passive landing shock-response control mechanism for aerial transport devices that combines a support spring with a granular damper. The primary objective is to suppress post-landing rebound to avoid attitude disturbance and mission interruption, while maintaining the peak acceleration at touchdown within a certain range without external power or active control. In the proposed mechanism, the impact energy is temporarily stored in the spring and then transmitted to the particle bed through a compression plate, and dissipated mainly through repeated particle–particle and particle–wall collisions, frictional sliding, and material losses. To clarify design effects on rebound suppression, spring stiffness and compression-plate geometry are selected as design factors and systematically varied under identical landing conditions. Numerical analyses are performed using a discrete element method coupled with rigid-body dynamics, with a contact model appropriate for the particle material. The results show that lower spring stiffness consistently reduces the maximum rebound height and also tends to mitigate the acceleration response immediately after touchdown. Moreover, compression-plate geometry significantly affects rebound suppression by altering particle rearrangement and compaction behavior. The peak acceleration at touchdown is within a certain range in most cases. These findings provide useful design guidelines for landing response control.

This paper proposes an efficient method for evaluating the intensity of the singular stress field (ISSF) at an interface corner in a three-dimensional (3D) bonded structure, where two distinct real singularity indices are involved. Finite element method (FEM) analyses are conducted for both unknown and reference problems using the similar mesh patterns. A known relation exists between the FEM-derived stress σ_FEM, the minimum element size e_min and the singularity index λ as σ_FEM ·(e_min)^1−λ= constant. Based on this relation, two singularity indices are simultaneously determined, and the FEM stress is discomposed into two components corresponding to each index. Then, the ISSF for the unknown problem is obtained from the FEM stress ratio of the reference and unknown problems. To demonstrate effectiveness of the proposed method, it is applied to a 3D scarf joint with a 45-degree scarf angle composed of steel adherend and epoxy adhesive. The results show that the ISSF can be analyzed with accuracy comparable to that of the H-integral method. Moreover, the 3D corner ISSF for the scarf joint is analyzed by varying width W, depth D and adhesive layer thickness h. It is found that when h/min(D,W) ≤ 0.1, the 3D corner ISSF depends solely on h. It is confirmed that the same failure stress can be obtained when the adhesive layer satisfies the condition and has the same thickness by using the previous experiment result.

Bamboo–plastic direct bonding was attempted via a fused deposition modelling (FDM) typed three-dimensional (3D) printer, aiming to enhance bamboo use. Polylactic acid (PLA) filaments were employed in 3D printing, and bamboo specimens were grooved via laser processing, hoping to attain the anchoring effect that provides a strong physical bonding. Because such many process parameters that are practically impossible to verify all the combinations of them exist, three parameters, the laser power (P), hatch spacing (h), and temperature of the 3D printer nozzle (θ), were selected and a Taguchi L9 orthogonal array was used to reduce the number of trials. The experimental results illustrated that P is the main effect for the depth of the laser grooves and h and interaction P×h are weaker but still significant effect. All the laser-grooved specimens demonstrated larger tensile strengths than the control specimens on average. From the main effect plot of the Taguchi method, the optimal conditions were P = 60% (of nominal maximum output, 20 W), h = 1.0 mm, and θ = 210°C within the experimental range. At the low laser power, P = 40%, insufficient penetration of PLA into the grooves led to lowering the tensile strength due to delamination at the bonding interface. Conversely, At the high laser power, P = 80%, and the narrow hatch spacing, h = 0.5 mm, the heat affected significantly onto the bamboo specimens and the islands of the hatch pattern were easily destroyed, resulting in decrease in the tensile strength.

In the present study, we investigated the transition in aggregate structures of a suspension composed of magnetic Janus particles under a uniform magnetic field. Monte Carlo simulations were performed to investigate how the transition of aggregate structures depends on various factors, such as the magnetic interaction between particles and the strength of an applied magnetic field. Here, we employ a particle model that has a magnetic moment radially shifted with respect to the particle center. The main results obtained here are summarized as follows. Janus particles with magnetic moments near their centers tend to aggregate and form chain-like clusters as the magnetic interaction strength increases. In the case of strong magnetic interactions, an increase in the distance between the magnetic moment and the particle center leads to a transition in aggregate structures from chain-like clusters to packed clusters. These cluster units tend to consist of 2 to 5 particles. As the magnetic field strength increases, chain-like clusters tend to be inclined toward the magnetic field direction. For Janus particles with magnetic moments near their surfaces, constituent particles in chain-like clusters tend to arrange so that their magnetic caps are close to each other. From these results, it is evident that both the strength of magnetic particle-particle interaction and the applied magnetic field strength have a significant influence on the internal structure of Janus particle aggregates.

The purpose of this study is to expand the use of unused heat. Demand for ice is expected throughout the year as a refrigeration and cold storage material. Therefore, we have studied an absorption refrigerator that produces ice from unused heat. The refrigerant is a mixture of H₂O and 1-propanol, and the working fluid is a mixture of H₂O, 1-propanol and LiBr. （1）The crystallization temperature of the working fluid, which provides constraints on operation, was measured. An equation for the crystallization temperature was developed as a function of composition and temperature. （2）Methods were developed to analyze the composition of liquids. The binary refrigerant was analyzed by refractive index. The ternary working fluid was analyzed by a combination of refractive index and surface tension. These methods are used for compositional analysis of the refrigerant and the working fluid in future absorption refrigerator experiments.

This study developed a pneumatic adaptive securing band (PneumaBand), which can gently hold large objects of various shapes using an inverse pneumatic artificial muscle (IPAM). An IPAM is a soft actuator that elongates when its internal air pressure increases and contracts when the internal air is evacuated. If PneumaBand is pre‑pressurized, it can be activated simply by releasing the internal pressure to the atmosphere, requiring no external power source during operation. It can also be used with a compressed gas cylinder or a compact air pump. PneumaBand can expand its inner diameter up to three times its original size and hold large objects with a circumference of exceeding one meter. It is foldable for compact storage, allows adjustment of the wrapping force through internal air pressure or manual changes in its initial size, features a simple and durable structure, and is suitable for outdoor use. In addition, it retains its wrapping force even if damaged. This paper describes the mechanical properties of the IPAM as well as the wrapping force and wrapping speed of PneumaBand, and discusses potential applications based on experiments. Experimental results show that PneumaBand can be used to secure and protect objects, fix items on shipping pallets, hang large objects, and function as a robot gripper.

Reducing the weight of beams is expected to reduce the total weight of structure, conserve energy and materials, and lower production costs. However, lightweighting generally leads to a decrease in stiffness. One problem arising from reduced stiffness is earthquake damage. Japan is a country prone to earthquakes, and large-scale earthquakes such as the 1995 Great Hanshin-Awaji Earthquake and the 2011 Tohoku Earthquake have caused damage to residential and industrial facilities. Therefore, this study focused on twisted beams as a method to enhance stiffness while achieving weight reduction. Twisted beams are modeled using finite element analysis with solid elements, and their static and dynamic load characteristics under cantilever condition and fixed end condition are investigated through analysis and experiments. By comparing analytical and experimental results, the validity of the analysis was verified. The results showed that solid element FEM analysis is effective for aspect ratios up to 0.15 under both support conditions. Furthermore, using this analytical method, the effects of the beam's aspect ratio and twist angle on static characteristics (such as stiffness and displacement) and dynamic characteristics (such as natural frequency) are investigated. Color maps are created to identify conditions yielding high stiffness. As a result, under the cantilever condition, higher stiffness is obtained through torsion when the beam width is small, whereas under both ends fixed condition, stiffness increased significantly at a twist angle of 180 degree regardless of the aspect ratio. Thus, the appropriate beam geometry and twist conditions that can achieve stiffness enhancement are clarified.

In recent years, the introduction of 5-axis machining centers has been increasing in order to improve productivity. Since the 5-axis machining center has two rotary axes, some geometric errors exist, which reduces the machining accuracy. There are several tests that calculate the geometric errors from the machined shape, but in most cases, it is difficult for 5-axis machining center users to understand the misalignment of the axis average line of rotary axis caused by geometric errors based on the machining results. In this paper, we propose a test method to calculate the geometric errors of a 5-axis machining center from the shape error of the workpiece machined by turn milling. The machining test is designed for each rotary axis. In both tests, the tool moves along an arc on the workpiece by moving one rotary axis and the two linear axes perpendicular to the rotary axis at different rotational speeds. From the experiment, it has been confirmed that the proposed method can intelligibly display the misalignment of the axis average line of each rotary axis and estimate the geometric errors inherent in the rotary axis.

One key challenge in the system integration business is improving the efficiency of schema matching. Schema matching is a task where two different schemas are given as input, and semantically corresponding columns are identified. Recent methods using large language models (LLM) outperform rule-based and deep-learning approaches. However, the LLM-based approaches face two challenges: improving matching accuracy of (i) one-to-many cardinality and (ii) foreign keys (FKs). For the first challenge, we focused on the features that the one-to-many or one-to-zero cardinalities can be excluded if the column is an identifier (ID) or essential for the target application (i.e. production planning system), respectively, and thus the possible multiplicity can be classified into four patterns. Based on the features, we proposed a decomposition approach where an original problem is divided into four subproblems according to the four multiplicity patterns, and we use prompts specialized for each subproblem. For the second challenge, we focused on the features that database schemas can be modeled as graphs, and the FKs can be identified in the shortest path between the primary keys (PKs); thus, FKs can be identified by graph path search between PKs. Based on the features, we proposed a graph-based approach where PKs are matched first using LLM, and each FK is matched later using graph path search between corresponding PKs. The effectiveness of our proposed approaches was demonstrated through an industrial case study.

eHMI (external Human Machine Interface) that displays texts and signs as a method of conveying a vehicle’s guidance intention into pedestrians has been actively developed. However, current eHMI has problems where the vehicle’s intention and purpose are difficult to understand for pedestrians, or the differences in language and culture lead to various interpretations. Therefore, a method of conveying intentions that pedestrians intuitively understand the vehicle’s intentions is required. This study focused on the eyes, which facilitate shared intentions in human-human communication, and developed an eye-type eHMI “i-EyFuze.” i-EyFuze has an intention conveying method that guides pedestrians by extracting the target pedestrian through image processing and superimposing the image of pedestrian on the vehicle’s gaze. It was confirmed that a self-shadow representation that protects interpersonal privacy is preferred for the image of superimposition. Furthermore, the evaluation of impressions of i-EyFuze based on a simulating traffic environment that mimics a pedestrian crossing confirmed the effectiveness of the proposed self-shadow. In addition, the evaluation of intention conveyance in the same environment showed that the conveyance of pedestrian guidance suggests may be enhanced when the moving self-shadow involves a slightly delay for vehicle’s gaze.

Automated design rule checking (DRC) is a critical component of Design for X (DfX) strategies; however, establishing general-purpose automated systems in mechanical design remains difficult due to the high degrees of freedom in 3D shapes and the limitations of Large Language Models (LLMs) in spatial reasoning. This paper presents a novel technology for the automated generation of CAD design rule check programs, aiming to enable designers without advanced programming skills to verify manufacturability using natural language instructions. We developed a robust library of "shape recognition functions" that handle complex Boundary Representation (BRep) data to extract specific features like holes and bends. Our proposed method automatically generates programs that appropriately combine these functions. A system architecture based on Retrieval-Augmented Generation (RAG) was implemented, utilizing a vector database to store function definitions. Upon receiving a natural language design rule, the system retrieves relevant function schemas and employs a generator LLM to synthesize an executable Python program. Prototype validation was conducted using a complex CAD assembly model containing over 300 parts. In a verification test focusing on the distance between holes and plate edges, the generated program achieved 100% precision and recall in identifying violations. Additionally, a broader evaluation across six distinct design rules by a non-expert user yielded a program generation accuracy exceeding 90%, following prompt optimization. These results demonstrate that combining RAG with specialized geometric libraries effectively addresses the challenge, providing a practical solution for automating complex CAD inspections at the design stage.

Ni-based alloy 690 exhibits excellent corrosion resistance in static environments; however the effect of corrosion on fresh surfaces is significant under tribocorrosion conditions, such as impact fretting wear in corrosive solutions. Understanding this behavior is crucial for accurately evaluating the corrosion rate and service life of this material, which is used in steam generators of nuclear power plants. In this study, impact fretting wear tests were conducted under electrochemical conditions to investigate the effects of non-contact time, displacement, and temperature. The results revealed that the progression of wear caused by impact fretting is primarily attributed to the mechanical removal of corrosion products and the anodic dissolution of the worn surface. Furthermore, the wear volume obtained from surface measurements exhibited a strong linear correlation with the dissolution volume calculated from the anodic current based on Faraday's law. The apparent activation energy obtained from the specific wear rate ranged from 13.5 to 23.1 kJ/mol, indicating that the wear process is primarily governed by anodic dissolution. An analysis of the decay behavior of the anodic current density following a single impact showed that the time required for repassivation of the worn surface ranges from approximately 12 to 72 ms. Moreover, it was observed that the peak current density which serves as an indicator of the exposure ratio of the fresh surface, increases with increasing displacement.

Micro-perforated panel absorbers (MPPA) are sound-absorbing materials based on Helmholtz resonance, consisting of a perforated panel with sub-millimeter holes backed by an air cavity. The absorption bandwidth is determined by the geometric parameters such as hole diameter, panel thickness, perforation ratio and cavity length. In recent years, various optimization-based approaches have been proposed to achieve both the broadband absorption and the compact structural configurations. However, most of these studies assume a normal incidence of sound waves, whereas sound waves are expected to be incident from random directions under practical acoustic environments. This study aims to realize both the broadband sound absorption and the compactness of MPPAs under random-incidence conditions. Multi-objective optimization is performed to identify the Pareto-frontier between the absorption bandwidth and the compactness. To evaluate the sound absorption characteristics of MPPA, the sound absorption coefficient is numerically evaluated by the boundary element method (BEM). Sequential approximate optimization using radial basis function network is employed to identify the Pareto-frontier. The effectiveness of the proposed approach is verified through numerical results and experiments.

Recent regulations on the spring-like effect (SLE) in golf drivers cap the characteristic time (CT) at 239±18 μs, which limits performance gains derived solely from face deflection. This study investigates an alternative approach: the design of sole geometries inspired by origami engineering. Building on folding patterns such as Miura-ori and Yoshimura, we developed analytical models incorporating origami structures into the sole. Finite element frequency-response analyses were conducted to compare face amplitudes, revealing that the application of a K-fold configuration significantly increases face displacement compared to a baseline model. To quantitatively evaluate the influence of design factors—specifically the number of longitudinal and transverse fold lines, zigzag ratio, and fold depth—on face amplitude, a parametric study was performed. Optimal conditions for the target club geometry were identified as (m, n, s, h) = (7, 5, 1/2, 1.5). The optimized K-fold model exhibited approximately 18.3 times larger face deflection and 16.9 times larger sole deflection versus the baseline, demonstrating a substantial increase in global head compliance. Furthermore, a physical prototype was fabricated based on the analytical results, and robot hitting tests were performed to validate the simulation and evaluate the effectiveness of the K-fold structure. The results confirm that the K-fold application enhances the rebound performance by increasing ball launch speed and carry distance without altering the overall stiffness of the club. These findings establish that origami-derived architectures are an effective mechanism for improving ball-flight performance under existing rule constraints.

This paper proposes a new seat structure that significantly improves the ride comfort of passenger cars. This new structure eliminates the conventionally used S-shaped spring and adopts a pan structure. Furthermore, the seat pad uses urethane foam, enclosing areas where load is concentrated with a sealed component and providing an orifice on the surface that does not come into contact with the human body. When the pad deforms due to load fluctuations, damping force is generated by the viscous resistance of the air passing through the orifice. The effect of the proposed seat specification on ride comfort improvement was verified through simulations and multiple experiments. The results showed that it is possible to achieve a high level of both handling stability and ride comfort.