The purpose of this study is to realize a recycling method for aluminum chips in solidification molding. In this method, aluminum chips are heat treated under different conditions, SPS is applied, and then HPS processing is performed. In this experiment, HPS processing was performed on heat-treated specimens under several conditions, and HPS processing was performed after SPS on the same specimens. The tensile strength and elongation were determined by tensile testing, and the hardness was determined by Vickers hardness testing, to clarify the effects of heat treatment conditions, SPS, and HPS processing. The microstructures were observed, and the theoretical values calculated by the theoretical equation were compared with the experimental values obtained by Vickers hardness testing．

Aquatic organisms that swim at high speeds, such as dolphins and tuna, use a propulsion method called lift propulsion, the mechanism of which has been the subject of much research. The propulsive force generated by the tail fins of aquatic organisms is extremely strong and has attracted much attention in biomimetic technology, especially in the study of fish-shaped robots. However, even though aquatic organisms swim near the water surface when feeding, few studies have focused on swimming near the water surface. We found that propulsive force increases when the frequency of water surface waves and fins are synchronized, and that turbulence of water surface waves attenuates propulsive force.

Recently, the use of robots to serve food in restaurants and other similar venues has become more common due to labor shortages. In addition, the use of humanoid two-armed robots to share tools and collaborate with humans has been considered. In our previous study, the use of a two-armed robot fixed on the floor to manipulate a ball on a plate has been investigated. However, as mentioned above, the inertial forces acting on the ball are controlled when the robot is moving. Therefore, this study focuses on the effect of inertial forces on the manipulation of balls on a plate. Using a lightweight two-armed robot that can be mounted on a small AMR, we investigated the effect of generating centrifugal force as a constant inertial force during linear and circular motions, using a static state fixed on a tabletop as a reference.

Numerical analysis technology is required for the design of heat and mass transport systems that use gas-liquid two-phase flow. Since interfacial transport between the two phases depends on the interfacial area concentration (IAC), the development of a method for predicting the IAC has been the key to refining gas-liquid two-phase flow numerical analysis technology. In this study, we developed a four-sensor probe capable of measuring local IAC and other parameters. We constructed a database of two-phase flows in large-diameter pipes and rod bundles on an industrial scale. Furthermore, we used a high-speed camera and image processing to build a database of two-phase flows in narrow channels used in research reactors. Based on these databases, we developed a series of constitutive equations for the IAC of gas-liquid two-phase flows.

In recent years, artificial light-type plant factories have been attracting attention due to the demand for stable food production in response to food shortages and climate instability. Despite their high productivity and stable year-round cultivation, the high initial and operating costs are still a problem. However, with the recent development of AI technology and the third plant factory boom, research on yield prediction combining machine learning and image recognition has been conducted in the field of food production. This enables more accurate prediction than growth prediction based only on environmental conditions around the crop by measuring the shape and color of leaves through image recognition. On the other hand, it has been reported that the phenotypes that contribute to the growth rate of a crop are caused by environmental factors during its growth stage. In this study, crops were grown in a controlled environment from the seeding stage, and the relationship between environmental history and phenotypes was investigated. This study investigated the relationship between environmental history and phenotypes. The plant model was introduced into an actual growing environment, and the accuracy of growth prediction was confirmed.

To realize a super-leanburn SI engine with a very-high compression ratio, it is required to design a new fuel which could have low ignitability at a low temperature for antiknocking, but high ignitability at a high temperature for combustion stability. Ethane shows a long ignition delay time at a low temperature close to that of methane, but a short ignition delay time at a high temperature close to that of gasoline. Ethane addition to gasoline could be a good example of fuel design to improve both combustion stability and antiknocking property. In a previous study, methane, ethane, or propane with the RON of 120, 115, or 112, respectively, was added to a gasoline surrogate fuel with the RON of 90. The ethane or propane addition advances CA10, resulting in the shortening of combustion duration. Any addition advances knocking limit. The advance of knocking limit is larger in the order of ethane addition > propane addition > methane addition, which is dependent on not the RON of the gaseous fuel, but the rate of OH consumption by the gaseous fuel. In the present study, methane, ethane, or propane has been added to a PRF with the RON of 90, 95, or 100, or toluene with the RON of 120, with the energy fraction of the gaseous fuel of 0.15, 0.25, or 0.35. For the addition to PRF90 or PRF 95, the advance of knocking limit is larger in the order of ethane addition > propane addition > methane addition. Any addition to toluene retards knocking limit. The retard of knocking limit is larger in the order of propane addition > ethane addition > methane addition, which is dependent on the RON of the gaseous fuel.

For future super-leanburn SI engines with very-high compression ratios, it is required to design a carbon-neutral fuel which could improve both combustion stability and antiknocking property. Research octane number, RON, is an antiknocking index. As RON increases, knocking limit combustion phase advances in the cylinder. The relationship between RON and ignition delay time has been investigated experimentally using shock tubes or rapid compression machines, or computationally using detailed reaction mechanisms. However, the relationship between ignition delay time and knocking limit combustion phase has been unknown. In the present study, an SI engine has been operated for different fuels with RON’s of 90 to 120. As RON increases, the heat amount from LTO decreases, and disappears at the RON of 1000. With the increase of RON, knocking limit CA50 advances straight. Then, ignition delay time has been computed under constant-volume conditions where initial pressure has been set at the in-cylinder peak pressure on the knocking limit cycle. The relationship between ignition delay time and knocking limit CA50 has been discussed. Knocking limit CA50 is dependent on in-cylinder pressure which can be initial pressure for the ignition delay time of tens of crank angle degrees with the initial temperature of 850 K to 950 K.

Simulation of flow generated by a moving object in an incompressible fluid is performed. The moving computational domain method is used in this simulation because the effect of the moving object on the flow field must be evaluated in detail. This method minimizes the relative displacement of the computational domain near the object by simultaneously moving the computational domain as the object moves. The method is based on the moving-grid finite volume method, which satisfies the flow and geometric conservation laws even when the computational grid is moved or deformed. This paper presents the method and results.

In this study, we compared the results of two conditions: one in which a superhydrophobic coating was applied over a wide area, and the other in which it was applied in part, taking into account the size of the longitudinal vortex, and investigated how the turbulent structure flowing over the superhydrophobic surface changed and contributed to frictional resistance, focusing on vorticity. As a result, in the Slip condition and Partial slip condition, the slope of the average velocity in the main flow direction near the wall was mitigated, and a slip phenomenon occurred. In addition, the Slip condition was observed at high values from any wall position, and a reduction in frictional resistance was confirmed. In the Slip condition and Partial slip condition, an increase in frictional resistance was confirmed at low Re_θ, and a reduction in frictional resistance was confirmed at high Re_θ. This means that the relative magnitudes of the effects of friction drag reduction due to flow direction slip and friction drag increase due to span direction slip change with Re_θ, and that when Re_θ increases, the superhydrophobic surface becomes relatively larger in relation to the longitudinal vortex, and the effect of friction drag reduction becomes dominant. Using the experimental data for each condition, we solved the FIK identity equation developed using vorticity, and confirmed that the effect of friction drag reduction that occurs when a superhydrophobic surface is installed is due to the reduction in vorticity fluctuations.

The Cold Spray method, in which powder materials are impacted onto a base material below melting temperature and at high velocities, is one of the coating technologies that can form a dense film with relatively little influence of heat or atmosphere. In order to elucidate the film formation mechanism of the Cold Spray method, in this study, we experimentally researched the stress-strain relationships of Inconel 718, Inconel 600, and Inconel 601, which are often used in the Cold Spray method. Compression tests are conducted in a wide range of strain rates from quasi-static strain rates (10^−3/s) to ultra-high strain rates (10⁴/s) to identify the strain rate dependencies of these materials. From the obtained results of these stress-strain relationships, we formulated a constitutive equation that can describe the stress-strain relationship at any strain rate employed in the Cold Spray method. Since the results of pure nickel and Inconel 718 have already been shown in previous reports, in this study, the results of Inconel 600 and 601 are presented．

Thermos bottles are expected to continue to play an active role in a variety of fields, ranging from familiar products such as water bottles and pots to recent applications such as the transport of vaccines and other pharmaceuticals and the transport of crystallized proteins in space development. However, as an effort to improve the usefulness of containers for transportation, new container shapes are being designed to increase the capacity and storage capacity. Deep drawing with a flange was adopted as the forming method. The purpose of this study is to understand the deformation behavior of materials in the deep drawing process of square containers to improve transportation efficiency, and to examine the optimized shape of the mold and blank for the target container shape of 100 mm cubic. In this study, the deep drawing process was reproduced by FEM analysis, and experiments were conducted using the shapes obtained from the analysis. The results showed that, in deep drawing with flanges, the reduction of the corner section and the selection of the optimum blank size reduced the compressive and frictional forces and made the flange section uniform, thereby improving the drawing depth. In addition, optimization of the spherical head height reduces bending stress and improves drawing depth.

SiC substrates are expected to be used in various applications as power semiconductor devices. However, SiC substrates are extremely difficult to fabricate into fine patterns due to their high strength, high hardness, and high chemical resistance. To minimize chipping of SiC substrates, a newly developed PCD (Poly-Crystalline Diamond) blade was used to apply pure water directly to a high-speed rotating blade using a brush. The machining accuracy of the SiC substrate and the surface roughness of the groove surface and the groove bottom surface are evaluated in comparison with dry machining and the supply of DI water by a nozzle.

The effects of strong strain processing on amorphization and corrosion resistance of High-entropy alloys were investigated. High pressure torsion was applied to FeCoNiCrAl0.8 alloy under five different working temperature conditions to prepare samples. Optical microscopy, transmission electron microscopy, and X-ray diffraction were used to observe the microstructure. Vickers hardness test was conducted for mechanical properties. As corrosion tests, minute curves were measured in 3.5 wt% NaCl solution and 0.5 mol/LH2SO4 solution. As a result, each sample contained both amorphous and crystalline phases and X-ray diffraction and thermal analysis (differential scanning calorimetry) showed that the samples had different amorphous volume fractions. Sample with the lowest amorphous volume fractions showed higher values for Vickers hardness. In corrosion tests, the specimen with the highest amorphous volume fraction was passivated in 3.5 wt% NaCl solution, indicating superior corrosion resistance. Also the sample with the highest amorphous volume fraction in 0.5 mol/LH2SO4 solution was found to have stable passivity and excellent corrosion resistance. In the amorphous-crystalline phase, we think Cr is enriched in the amorphous phase to form passive film., and ennoblement of the pitting potential is explained by the enrichment of the solute in the amorphous matrix. Precipitation of crystalline induces enrichment of chromium in the amorphous phase, making the matrix phase more pitting-resistant. The presence of a critical size of nanocrystals in improving localized corrosion resistance has also been pointed out. Below the critical size, a chromium-enriched highly protective passive film can cover the entire alloy surface, but preferential dissolution of a less corrosion resistant phase occurs when the size of the precipitates exceeds the critical size.

Drawing process is accompanied by a surface roughness after processing, which causes a loss of functionality. In this study, the surface deformation behavior of each part in the drawing process was evaluated. The surfaces of specimens with different drawing heights were observed with a laser microscope. The deformation behavior of the drawing test was confirmed by the finite element method. The strain in the part of product was confirmed by FEM. The roughness of each part of the product was also confirmed.

Corrugated cardboard, known for its high cushioning properties and strength, is widely used in transportation. In the present study, we focused on the cross-sectional structure of cardboard with voids. Aiming to produce a lightweight, high-strength corrugated cup, we formed the drawn cup with a void structure and evaluated its strength. In the experiment, test material used was pure titanium sheet TP270. The blank had a thickness of 0.3 mm and a diameter of 80 to 90 mm. The special die used was the roller ball die (RBD) with steel balls tightly packed into the shoulder of the die. The diameter of the steel balls ranged from 6 to 8 mm. The punch had a corner radius of 4 mm and a diameter of 39 mm. Both the punch and die underwent conventional heat treatment. The formability of the clad cup was investigated, including the adhesion between the constituent cups, residual stress of the cups, compressive strength, and plate thickness distribution. The drawn cup did not break, and a corrugated layer was formed uniformly on the cross section of the cup. Furthermore, the maximum sheet thickness reduction rate was approximately 10 % or less. It was also found that it was possible to form the drawn cup with a void structure that exhibits high adhesion and high compressive strength.

With industrial advancements, aerospace, energy, and medical fields demand stronger, more durable, and lightweight materials. Ultrafine-grained (UFG) structures, achieved through severe plastic deformation (SPD) techniques like Equal-Channel Angular Pressing (ECAP), enhance mechanical properties and corrosion resistance. However, literature on UFG effects on corrosion resistance remains inconsistent, likely due to microstructural complexity. In this study, Fe-12Cr alloy underwent ECAP (8 passes) for grain refinement. Dislocation density was evaluated using X-ray diffraction and the Williamson-Hall method, and low-temperature heat treatment was applied to selectively reduce dislocations without grain growth. EBSD confirmed grain sizes of 30–50 nm. Despite refined grains, heat-treated samples showed decreased pitting corrosion resistance. The results suggest that dislocation density plays a crucial role in corrosion resistance, indicating that grain refinement alone is insufficient, and residual dislocations are key to improving corrosion resistance.

Zero-emission vehicles, such as electric vehicles and fuel cell electric vehicles, are becoming increasingly popular in response to automobile emission regulations. However, in developing countries and other regions, there is expected to be much demand for passenger cars still powered by internal combustion engines. For this reason, it is essential to further improve the thermal efficiency and environmental performance of heat engines. However, since fuel is difficult to vaporize when the engine is started and in the cold state, a large amount of fuel adheres to the port tubes and combustion chamber walls, causing unburned hydrocarbons (HC) and particulate matter (PM) to be generated. The purpose of this study is to understand the behavior of the fuel film formed by the wall impingement of fuel spray in the intake port. In this report, spray characteristics were determined using scattered light photography, and the fuel film formation process was analyzed using the TIR-LIF method. The experimental results showed that fuel film area was larger in the flow field than in the stationary field, but the amount of fuel adhesion was smaller in the flow field. These results indicate that the atomization of the spray has a large influence on the fuel film formation process in the stationary field, while the arrival rate of droplets to the wall surface has a large influence in the flow field, because the droplets are swept away by the gas flow.

In recent years, ammonia fuel has gained attention as a marine fuel option aimed at decarbonization. However, during the combustion process of ammonia fuel, nitrous oxide, which has adverse environmental effects, is generated. It is known that nitrous oxide can be decomposed using hydrogen atoms. A potential method to produce hydrogen atoms is through the application of voltage to steam, creating a plasma state that generates hydrogen atoms. In this study, we designed a pressure vessel equipped with electrodes to conduct experiments for elucidating the discharge characteristics in a steam atmosphere. Additionally, nitrous oxide gas was introduced into the vessel to evaluate its removal efficiency. The results of these investigations are reported here.

In this study, we experimentally investigated the effects of heating the urea solution film after attaching the impingement wall, with the aim of developing a technology to promote ammonia production by optimal heating control even under low temperature exhaust gas conditions. First, the two heating configurations of UWS before injection and impingement wall are then introduced into an experimental system simulating a real exhaust pipe. The conversion rate from UWS to ammonia and isocyanic acid at the catalyst inlet of the spray after impacting the impinging diffuser in the two heating configurations is then determined. To understand the effects of heated UWS and heated impingement wall, the gas composition behind the exhaust pipe was analyzed by using FTIR. Finally, we have obtained the time series data of the NH3 concentration distribution by changing the UWS temperature and the impingement wall temperature and clarified the NH3 generation process by experimental analysis.

Impact wrenches cannot apply torque at the specified value. Since impact wrenches tighten with impact force, insufficient or excessive axial force of the bolt can cause serious problems. We set up conditions that reproduce the actual operating environment, tightened the bolt and recorded the strain of the bolt and the rotation angle of the socket. From the results, we confirmed the “relationship between the number of impacts and the axial force” and the “relationship between the rotation angle of socket and the axial force” to evaluate the mechanical characteristics of the impact wrench.