In recent years, space exploration has become increasingly active, with NASA leading the Artemis Program. This program aims to establish a lunar base as a steppingstone for resource exploration on the Moon and future human missions to Mars. The program is divided into three phases: Phase 1 involves lunar landing, Phase 2 focuses on expanding exploration areas and building infrastructure, and Phase 3 aims for sustained activities on the Moon. Phase 2 includes constructing a small-scale lunar base, developing pressurized rovers, and building power systems. Due to the harsh lunar environment, such as up to 360 hours of darkness and high transportation costs, technologies for energy storage and high energy density power generation are crucial. This study compares solar power, solar thermal power, and small nuclear reactors, assuming energy storage using lithium-ion batteries. The evaluation considers factors like system weight, energy density, supply duration, and installation area to identify the optimal power supply method for lunar bases.

In this study, the internal standard method, a type of X-ray diffraction method, was used for the quantitative analysis of rust. Internal standard samples were selected and calibration curves were prepared with standard samples (iron hydroxides α, γ, and ferric tetroxide). In addition to the conventionally used calcium fluoride and zinc oxide, the chemically stable magnesium oxide was employed as the internal standard sample. Standard deviation, coefficient of determination, and residual plots were used to evaluate the calibration curves. As a result, it was confirmed that the variation tended to be larger in the higher concentration range, and the analysis of the coefficient of determination and residual plots indicated that the calibration curve was more accurate when approximated by a curve. The calibration curve using zinc oxide (ZnO) was the most accurate, and the quantitative analysis using a simulated rust sample showed the smallest error of approximately 1%.

Lead zirconate titanate is a typical piezoelectric material, but it is becoming subject to regulations, and lead-free piezoelectric ceramics are attracting attention as an alternative material that does not use lead. In this study, we attempted to fabricate piezoelectric ceramics by corrosion reaction of Ti and Bi. For example, in the preparation of Bi₄Ti₃O₁₂, NH₃ solution and Ti were first added to H₂O₂. And then, Ti was dissolved in the solution completely. Next, HNO₃ solution in which Bi dissolved was added in Ti solution above in small amounts and stirred. Ammonia was further added to mixed solution above to adjust pH. And Bi₄Ti₃O₁₂ powder was obtained after filtrating, drying and calcinating.

In this study, we investigated the accuracy of self-position estimation for a small autonomous mobile robot using the M5GO accelerometer, which estimates position by dead reckoning after removing noise from the M5GO acceleration data. Noise was removed by offset correction and setting a threshold value, and the accuracy of self-position estimation was confirmed when M5GO was moved 200 mm. As a result, although the noise could be removed when the M5GO stopped, it continued to move because the sum of the acceleration at the moment it moved and the acceleration at the moment it stopped did not equal zero. This may be due to the effect of gravitational acceleration and the size of the threshold value. Therefore, M5GO's self-position estimation needs to be improved.

Currently, the aging of many infrastructures and the decrease in the number of workers due to the declining birthrate and aging population are becoming more serious, so it is necessary to reduce work force and improve the efficiency of measurement work using ground-penetrating radar. High accuracy of self-position estimation is required for the expected automation of inspection work by autonomous mobile robots. In a previous study, we attempted to improve the accuracy of self-position estimation by using sensor fusion of an encoder and an IMU sensor on a robot equipped with a mecanum wheel as a high-precision position estimation. As a result, although the accuracy was improved, it did not reach a satisfactory level. One of the factors was vibration and wheel slippage. In this study, we analyze the correlation between the vibration data and the position estimation accuracy by sensor fusion, and investigate a correction method.

The number of infrastructure facilities in Japan that require inspection is expected to increase rapidly in the future. In addition, currently, infrastructure equipment inspections are performed manually, but the decrease in the number of inspection workers is also a problem. In particular, hand-push measuring trolleys equipped with underground radar are used for inspection work on underground infrastructure equipment, but this requires a great deal of labor and time, so the introduction of robots is required to improve efficiency and save manpower. It is being done. When robots perform inspection work on underground infrastructure equipment, they may be required to travel long distances of several tens of meters or more, and highly accurate self-position estimation is required for autonomous movement. In this study, we investigated a method to calculate the absolute coordinate position of a robot from the color information and depth information of the four corner points of an AR marker using an RGB-D sensor.

In this study, reason for the anisotropy of work hardening behavior in polycrystalline α titanium with transverse direction (TD) split texture was investigated using crystal plasticity finite element (CPFE) analysis. The CPFE analysis successfully reproduced the anisotropy of stress- strain curves even though the effect of dislocation on work hardening was ignored in the condition of analysis. When the relationship between change in work hardening rate and activation of slip systems was investigated using the results obtained by the CPFE analysis, the decrease in work hardening rate was closely related to the activation of primary and secondary slip systems; the activation of primary slip system determined the yield strength and the activation of secondary slip system decreased the work hardening rate due to change in deformation incompatibility between grains. This result shows in the current α titanium that prismatic slip system is the primary slip system and 1^st pyramidal <a> slip system is the secondary slip system, and the activation timings of these slip systems are different depending on tensile direction, resulting in the anisotropic stress-strain relationships.

First, how to use the interFoam solver, which is capable of free surface analysis, was investigated for an analysis problem of a general small boat moving on a wave-rough water surface. It was found that it is necessary to make the free surface above and below the sea surface dense and generate a cubic grid. Next, we applied this solver to the flow around an automobile tire housing. In snowy and cold regions, the formation of ice blocks on tire housings in winter is a problem, and we are currently researching the suppression of ice block formation using plasma actuators (PA). We confirmed that analysis using interFoam can effectively simulate the visualization results of the flow around a rotating tire. We will use it to identify problems in wind tunnel models and to consider the position of PA electrodes.

Special test devices to study the weather resistance of wind turbine blade leading edge protection devices (LEPs) in snowy and cold regions were developed. First, a water spray test machine to deal with the icing phenomenon was developed. In the water spray test, the water spray test machine was operated in a temperature-controlled room cooled to -20°C, and ice was formed on the test LEPs by spraying water on it. Next, in the rotation test machine we developed, the test LEP after icing was rotated at about 3000 rpm, and the icing force was calculated from the centrifugal force when the ice was blown away by this rotation. In addition, a special wind tunnel allows continuous testing to deal with erosion by sand and other substances. The test machine was inspired by an air-blowing lottery machine, the wind tunnel outlet was modified to be vertical, and a pseudo-erosion source continuously collided with the LEP installed at the top.

Motion of plastic particles floating on water surface driven by a point-sourced bubble plume is investigated experimentally. According to PIV measurements of water surface flow and PTV applied for plastic particles, we found that particles moved significantly slower than the water surface. The ratio of the particle velocity to the surface flow dips at 50 % in the maximum case. This was attributed to gravity waves propagating on the water surface, of which origin is generated by periodic upheaval of water surface above the bubble plume. We also measured the floating particle motion in a larger water reservoir and found two regimes of the particle motion in the radial direction: the near field having two-dimensional diverging flow and the far field with logarithmic decay of the velocity due to combination of momentum dissipation of the surface flow subject to the gravity waves.

Heat and mass transfer at a vapor-liquid interface is a phenomenon caused by the non-equilibrium nature of molecules near the interface. In this study, we focus on the behavior of gas molecules near the boundary and report the results of molecular simulations to investigate the values of mass and momentum adaptation coefficients.

The Martian atmosphere differs significantly from Earth's in that it is extremely low in density and pressure, making it difficult to generate sufficient lift for aircraft. Accurate aerodynamic analysis is essential to design efficient airfoils and to predict flight performance under Martian conditions. In this study, a two-dimensional compressible fluid dynamics code has been developed to contribute to the design of Mars exploration aircraft. Numerical simulations are performed in the flow around a two-dimensional circular cylinder in the low Mach number regime for a validation of the developed code. The obtained drag coefficients are compared with experimental data over the Reynolds number range from 10² to 10⁵. The results show that the drag coefficients obtained by the numerical analysis are generally in good agreement with those of the experimental data. The quantitative inconsistencies are thought to be due to factors such as the grid resolution near the wall surface, the number of inner iterations in the time integration method, and the absence of three-dimensional structure in the two-dimensional flow.

The effect of running-in on the efficiency of a swash plate axial piston pump was investigated by continuous operation. The shaft speed was 1500 rpm and the discharge pressure was 20 MPa. The experimental results showed that running-in slightly decreased the volumetric efficiency, but increased the mechanical efficiency, resulting in an increase in total efficiency. The momentum of the increase in mechanical efficiency was also significant within 0-40 hours of operation. And when the performance curves were obtained, a decrease in the oil temperature difference between the suction and discharge ports due to the running-in effect was observed.

One solution to environmental and resource problems is the reuse or recycling of waste. Recycling requires intermediate treatment in which waste is sorted by material. Conveying waste after sorting in a jig thickener using a screw conveyor with brushes has been considered. However, there are no examples of its use in water, and the effects of conveyor angle, speed, and pitch on conveyance are unknown. In this study, the theoretical and experimental particle velocities were compared. At low rotational speeds, the screw feed rate significantly influenced particle velocity.

The purpose of this experiment is to develop a floating tidal current generator using a wind lens. In this experiment, a model of a floating tidal current generator was designed, and the results were examined to determine whether the device could generate power both in the water and in the air.

The structure of the device was designed so that the inner ring is a coaxial reversing mechanism, which enables the device to offset torque and generate electricity.

The results of the experiment showed that the voltage waveforms in the water and in the air had similar characteristics. This waveform was caused by the continuous flow of the voltage value becoming “+” when the N-pole approaches, approaching 0 when it is positioned directly under the coil, and becoming “－” when it moves away from the coil. This suggests that power is being generated without problems.

A Stirling refrigerator has a structure in which a high-temperature compression section and a low-temperature expansion section are arranged via a regenerator, and generally uses a single-phase gas as the working fluid. The regenerator contained in Stirling refrigerators acts as a heat storage material that exchanges heat as the working fluid flows through it, and its specifications determine the performance of this type of refrigerator. This study presents the results of an experimental evaluation of cooling performance using a regenerator made of thin stainless steel wire, when the wire diameter, bulk density, and refrigerator operating speed are changed.

Latent heat storage, which utilizes the heat of phase change of a material, has a large heat storage density compared to sensible heat storage and is a useful heat storage method that can realize space saving. Reducing the heat storage and release time is expected to expand industrial applications and is also desirable from the viewpoint of design convenience. This report presents the results of the measurement and evaluation of the melting latent heat storage rate using a differential scanning calorimeter for a latent heat storage material in which fine multi-walled carbon nanotubes (MWCNTs) with high thermal conductivity are solubilized and dispersed.

Japan aims to achieve carbon neutrality by 2050, reducing greenhouse gas emissions to net zero. In Hokkaido, CO₂ emissions from the transportation sector are higher than the national average due to long transportation distances, a short electrified railway network, and high energy consumption for vehicle heating. This study focuses on railway transportation and investigates the decarbonization of key railway transport routes in Hokkaido. Currently, three major options for railway decarbonization are being considered: electricity, fuel cells, and biodiesel . However, a concrete direction has not yet been established. This study targets the non-electrified sections with high freight transportation demand, specifically the Asahikawa–Abashiri and Sapporo–Kushiro routes, which follow the Hakodate–Sapporo route in importance. It examines railway vehicles using the three fuel types mentioned above. Furthermore, the study compares the initial costs, operating costs, and maintenance costs for transportation on each route to assess the feasibility of implementation. Based on the results, an optimal carbon-neutral scenario will be proposed.

The intermittency of renewable energy sources, influenced by weather conditions and other external factors, poses a significant challenge to ensuring a stable power supply. To mitigate this issue, energy storage systems are essential. Currently, electrochemical storage batteries are the predominant solution; however, they rely on rare metals such as lithium and cobalt, raising concerns regarding resource scarcity and environmental impact. Therefore, the development of sustainable and environmentally benign energy storage technologies is a critical research priority. This study aims to develop an innovative energy storage and power generation system that leverages the dissociation and expansion characteristics of CO₂ hydrate, as well as the pressure differentials induced by phase transitions between the liquefied and vaporized states of CO₂. For the practical implementation of the proposed system, numerical simulations are indispensable. In this paper, we present the simulation methodology employed for performance evaluation.