The stress propagation for a three-dimensional elastic sphere under a diametric loading condition in the framework of the linear elastodynamics is revisited. By describing displacements in terms of scalar and vector potentials using the Helmholtz theorem, the Navier-Cauchy equation, the time evolution equation for displacements, is converted to the wave equation. The wave equation is Laplace transformed and further solved in spherical coordinates to develop the tabular expressions for displacement and stress in terms of modified spherical Bessel functions, and the coefficients are determined to satisfy the initial and boundary conditions. The obtained solutions are given in the form of an inverse Laplace transform. For the steady solution, the long-time limit of the obtained solutions is derived by using the final value theorem of the Laplace transform. The unsteady solutions are obtained by applying the residue theorem of complex analysis by adding a path with zero contribution in the complex plane. The obtained solution includes longitudinal and transverse waves, and also Rayleigh waves propagating on the surface. The origin of the von Schmidt wave is discussed as a reflected wave produced by the longitudinal wave travelling on the surface. It is also discussed that the wave is bent, unlike in the case of semi-infinite systems.

Finish blanking is a process that increases the burnished surface using rounded cutting edge of the tools. In this study, the double-sided blanking was carried out using dies with different radius of cutting edges to investigate the effect of the radius of die cutting edge on forming of the burnished surface. A high-speed camera was used to capture the material deformation during blanking process, and analysis was carried out using Digital Image Correlation (DIC). The following results were obtained from the observation of material deformation during blanking. The length of the burnished surface is increased with increasing the radius of die cutting edge, because the punch stroke when the crack is occurred near the die cutting edge becomes large. When the radius of the die cutting edge is further increased, the crack occurs in the sheet material in contact with the middle of the die cutting edge. Therefore, the burnished surface is increased. The relationship between the mechanism of increasing the burnished surface and the radius of the die cutting edge is clarified. When the radius of the die cutting edge is increased, it becomes difficult to increase the equivalent strain and the maximum principal strain. However, the maximum principal strain in the part of sheet material increases as the part of the sheet material approaches the side of the die.

The deflection behavior of square sandwich panels with corrugated core of trapezoidal cross section at different pitch lengths and heights of trapezoidal pattern was investigated using the FEM analysis, where the panel size was fixed at total height of 13.6 mm and panel side length of 600 mm. FEM analysis was performed under the condition that four sides were fixed and uniformly distributed load was applied. With decreasing the pitch length, the panel deflection decreased. At extremely short pitch length, the panel deflection increased with decreasing the pitch length because the conversion of the external load into the shear force became ineffective by small amount of bonding area. On the other hand, with increasing the pattern height, the panel deflection increased. This behavior of deflection could be approximated by Gompertz curve, and the suppressive factor of deflection was considered to be the inclination angle of trapezoidal pattern. The larger the bonding width, the higher the inclination angle and the lower the pattern height of the inflection point. Moreover, with increasing the pattern height, the weight ratio of the panel decreased. This is because the reduction in the weight of the panel due to the thickness reduction is greater than the effect of increased deflection due to the increased pattern height. The product of panel deflection and weight ratio became minimal at a given pattern height. This suggests adaptability to weight reduction needs or stiffness needs by selecting the appropriate pattern height, and the compatibility for both needs can be met at the minimal point.

In order to improve a vibrational power generator using a magnetostrictive material, i.e., Iron-gallium alloy, and flow-induced vibration of a cantilevered cylinder, a fixed splitter plate was installed behind a cantilevered circular cylinder. Effects of a gap between a splitter plate and a circular cylinder on the performance of the response amplitude, the power of the flow-induced vibrational power generator and the vortex shedding frequency were investigated through wind tunnel experiments. Flow visualizations around a circular cylinder were also conducted by a smoke-wire method using a high-speed camera. The test models had a span length L of 200 mm, 300 mm and 400 mm. The diameter of a circular cylinder D of 40 mm. A splitter plate with a length of 400 mm and a thickness of 2 mm was installed behind the center of the model with a gap G varied from 8 to 104 mm. For a small gap ratio of G/D ≤ 0.6, galloping vibration occurred. From the smoke wire visualization, it was related that the upstream flow to the cylinder went along a side surface of the cylinder and the inner circulatory flow was generated near the gap. As a result, the accelerated gap-flow occurred and the negative pressure was generated periodically on the upper or lower side wall of the cylinder. For a large gap ratio of G/D ≥ 1.2, galloping vibration did not occur, and the response amplitude became similar to the circular cylinder without a splitter plate. The power generation of a circular cylinder having L = 200 mm with G/D = 0.2 was largest. However, the onset wind velocity of vibration was larger than that of the other cylinders and gaps.

Air flow field around narrowly arrayed out-door units of air conditioners is investigated experimentally under real-world operation conditions. The air flow velocities at the intake panels and exhaust ports of individual units are measured using hot-wire anemometry. The velocity data are analyzed upon Eulerian grid space to reconstruct the three-dimensional flow structure using Laplace equation for geometric interpolation and fluid dynamic laws to satisfy the equation of continuity. This approach enables the estimation of the recirculation rate of heated air into the intake planes, horizontal entrainment induced in the central region, and channel flows near the floor. Furthermore, we investigate the effect of sun-shading sheets, quantitatively assessing their advantages in shielding the air flow atop the units.

Dry storage of adsorbent reactors after contaminated water treatment in decommissioning contributes to reducing the risk of contamination spread. In general, the drying process of wet particles involves the simultaneous heat and mass transfers in the particle bed, and the thermal flow becomes complicated. In this study, a simulation model considering the physis involved in the bed, such as the structure of the vessel, the distribution of the initial moisture content, and the resistance of heat and mass transfer, was presented. Predictive calculations of the temperature and moisture content in the drying bed in full-diameter vessel were then performed. In addition, the reproductions of the temperature and the amount of evaporation were confirmed by comparison with the actual measurement results. This model was useful for examining heating methods and predicting drying time. Approximately 100 hours after the start of heating, the adsorbent in contact with the inner surface and bottom of the steel container was dried, and it was thought that it is possible to prevent moisture from coming into contact with the container even during long-time storage. Furthermore, by appropriately setting thermal boundary conditions on the top surface of the packed bed, it was able to improve the prediction accuracy of local moisture content.

Since the optimization results obtained by topology optimization depend on the size of the design domain, it is desirable to optimize the design domain as well during topology optimization. In this study, we propose a method to optimize the structural topology for solid structures by topology optimization based on the SIMP (Solid Isotropic Material with Penalization) method, while optimizing the design domain by shape optimization. In other words, we develop a simultaneous optimization method of shape and topology for structures. Under the constraints of volume and equilibrium equations, the compliance as the objective function is minimized. After formulating this design optimization problem, a sensitivity function is derived using the Lagrange multiplier method and adjoint method, which is applied to the H¹ gradient method to determine the optimal shape and topology. The introduction of the H¹ gradient method allows to optimize the shape and topology while simultaneously smoothing the outer shape and obtaining the topology without gray scale and checker board issues and also decreasing the objective function. The effectiveness of the method for topology optimization with the optimized design domain by shape optimization, or the simultaneous design optimization of solid structures is confirmed using numerical examples.

Conventional speech emotion identification often uses sentence units as analysis length generally. However, human emotions frequently change their emotions instantaneously when they hear a specific word or keyword that affects each speaker’s emotion, and it is important to capture more detailed emotional expressions for recognition of the emotion. We propose an emotion identification by using acoustic features that analyze speech at each frame, which are shorter than conventional units such as sentences and phrases for capturing and expressing actual emotion. Therefore, we propose a real-time emotion identification system that uses frames as the unit of analysis for acoustic features to the emotion in units of words and morphemes, which are shorter than conventional linguistic units.

In order to estimate the thickness of adhered thin liquid film on lubricating surface using ultrasonic method, a synthetic wave of reflected waves at the solid-liquid interface and multiple reflected waves in the thin liquid film was calculated and the fundamental relationship between the amplitude (echo ratio) and frequency spectrum (resonant frequency) was investigated with respect to the film thickness. As the film thickness increases, the echo ratio begins to decrease from a thickness around 1/8 of the wavelength λ₂ in the liquid, reaches a minimum around λ₂/4 and then increases in the thick film region. On the other hand, the resonant frequency during this process only decreases monotonically as the film becomes thicker, unlike the echo ratio. Therefore, the estimation of the film thickness becomes easier by using the resonant frequency. However, it is impossible to estimate the film thickness below λ₂/8 using these indices. For thickness estimation of such a thin adherent film, the difference wave obtained from the difference in amplitude between the reflected wave at the dry surface and that of adhered film is effective, and the difference echo ratio determined by its maximum amplitude decreases monotonically as the film becomes thicker in the region below λ₂/8. These fundamental relationships were similarly observed in the experiments with ethanol as the adhered film, and they almost agree with the calculation results for each of the above-mentioned indices using the actually measured ultrasonic frequency spectrum. Thus, the difference echo ratio is effective for estimating the adhered film thickness in very thin film region, while the resonant frequency determined by the period of the resonant or difference wave and the echo ratio of the reflection or difference wave are effective for the estimation of the adhered thickness in thicker film region.

This paper describes a practical method for estimating the contact condition between wheel and rail using an instrumented wheelset in a railway vehicle. In a previous study, it was confirmed that an observer based on Kalman filter can estimate wheelset motion variables from measurement data of the instrumented wheelset using a single-wheel creep-force model. However, in the previous method, there is still a problem in that a precise value of friction coefficient between wheel and rail is required as a model parameter to estimate the wheelset motion variables with high accuracy. The accuracy of the value of friction coefficient affects the accuracy of estimation values since a single-wheel creep-force model refers to the creep force and the creepage. Moreover, the decision of the creep force heavily depends on the friction coefficient. To solve the problem, this study proposes a method to estimate the wheelset motion variables and the friction coefficient simultaneously by modifying the plant model. The estimation performance of the proposed method is verified by vehicle dynamics simulations and running test data. The verification results show that the proposed method is effective in estimating the friction coefficient when the track curve radius is smaller than or equal to 600m. In addition, the proposed method can improve the estimation accuracy of the wheelset motion variables compared to the previous method.

Instrumented wheelsets are widely used in the railway industry for the purpose of measurement of the wheel-rail interaction forces, which are crucial factors in a running safety assessment. The lateral force, which is the lateral component of the wheel-rail interaction forces, is measured using strains induced by bending deformation of the wheel web in typical configuraions of instrumented wheelset. In addition to the use of bending deformation, the author has proposed a new configuration of instrumented wheelset which usitilizes shear strains of wheel web as a measure of lateral force. In these principles of lateral force measurement using bending or shear strains, the measurement accuracy descreases when a loading point of wheel load, which is the vertical component of wheel-rail interaction forces, is shifted laterally since the wheel load also induces the bending and shear strains. In this research, output characteristics of several types of bridge circuits, which are categolized as “axially-asymmetric bridge circuit,” are investigated for the purpose of reducing the influence of wheel load and improving the measurement accuracy of lateral force. Numerical investigations using a finite element method and experimental investigations are carried out and the results show that the axially-asymmetrization of the bridge circuits is effective to reduce the infuluence of wheel load.

This paper presents a simplified method for launch vehicle coupled loads analysis (CLA) with spacecraft which is normally conducted in the process of the spacecraft development. The method allows spacecraft developers to calculate coupled vibration response of their own without performing transient analysis for the coupled whole system model. A new method, which allows us to obtain coupled vibration response by convolving non-loaded acceleration time history at the spacecraft boundary with corresponding impulse response of combined apparent mass matrices in frequency domain, has been proposed. The proposed method functions well in any CLA cases including lift-off forced events where loads accompany quasi-static component in nature. We propose a novel approach to escape the error caused in the process of convolution for the quasi-static event by making use of the method to convolve only dynamic acceleration response extracted from the original acceleration by inertia relief technique. Finally, we demonstrate the validity of the proposed method through the analysis using practical launch vehicle and spacecraft models.