It was found that frequency spectra of vibrations in rotating disks of a helium-air mixture gas filled HDD sometimes showed anti-resonances between disk mode frequencies. It indicates that the flow excitation forces were coherent and can be represented by a load on a single point. In this paper, the angular and radial positions were estimated by anti-resonances in the frequency spectrum of disk vibrations and the difference of vibration amplitudes between spindle and disk modes. Comparing the estimated locations and the drive structure, they were coincident to the end of disk shroud and the top of trailing edge of spoiler. Therefore, it is suspected that vortices generated in the wakes after these structures were the root cause of large disk vibration in the helium-air mixture gas filled HDD.

Hydrogen embrittlement of metals is a phenomenon in which hydrogen entry into a material, such as steel, reduces its fracture strength and ductility. It is known that the hydrogen embrittlement susceptibility of high strength steels increases with strength, and hydrogen embrittlement is a major issue for high strength bolts, wires, springs used in automobiles, and high strength steel sheets. In this paper, the pure iron was immersed in a 0.05 M-H₂SO₄ solution and added hydrogen. In doing so, we analyzed the effect of connecting the pure iron to other metals and separating the load support point and the hydrogen generation point to prevent hydrogen entry into the pure iron.

Hydrogen entry into the pure iron is suppressed when the metal is connected to the pure iron and immersed in the 0.05 M-H₂SO₄ solution, compared to the pure iron alone. The hydrogen content of the pure iron is not determined solely by the difference in standard electrode potential between the metal to which it is connected. When the platinum is connected, the entire immersed area of the pure iron does not become an anode, and the anode and cathode areas may be mixed.

Gantry cranes for container handling installed on quays can cause unexpected runaways due to strong wind. In this paper, we conducted a fundamental experimental analysis to clarify friction characteristics between pads of rail brake, which is one of anchoring devices of crane, and rails under dry condition. We measured friction forces between pads and rails under analysis conditions with considering pressing condition of actual cranes' pads. Dynamic friction coefficients between the pads and the rails showed decreasing trends when sliding distance increased.

Wire ropes for cranes which is widely used in the construction and manufacturing industries must be replaced periodically to prevent the wire ropes break. According to the Structural Standards for cranes, wire ropes must be replaced or disposed when break 10% of the wire constitute the wire ropes. However, the number of broken wires cannot to be investigated accurately, because it is difficult to observe the inside of the wire ropes by visual inspection. Therefore, it is considered that clarification of the relationship between loading history and residual strength of wire ropes can be used as a disposal criterion for wire ropes, regardless of the number of broken wires. In this study, the relationship between loading history and residual strength of wire ropes tested by S-bend fatigue was clarified for IWRC 6×Fi(29), a wire rope commonly used in cranes. And the criteria for disposal based on the damage degree of wire ropes is investigated. The relationship between the residual strength of the wire rope subjected to cyclic S-type bending fatigue and the damage degree is shown that the residual strength of the wire rope subjected to 75% damage degree was equivalent to the breaking force based on JIS G 3525. In order to continue to use the wire rope with the breaking force based on JIS G 3525 and safety factor generally satisfied, it is considered that the wire rope may be better disposed of when the damage dgeree of the wire rope reaches 75%.

The gondola of the building maintenance unit (BMU) installed on the roof of a building for window cleaning suddenly fell during work after about a year owing to fracture of the main shaft of the wind-up drum in the BMU. The cause was investigated by fractographic observation of the fracture surface using scanning electron microscope (SEM) and stress analyses caluculated by the finite element method (FEM). Striations as the characteristic of fatigue fracture are observed by SEM on the fracture surface of the main shaft. FEM alalyses show that the tensile stress equivalent to the yield stress of JIS S45C is applied to the surface of the main shaft in case of 1 mm misalignment between the main shaft and driven shaft. Owing to the misalignment between the main shaft and driven shaft, the main shaft of the wind-up drum was subjected to a tensile stress equivalent to the yield stress of the material of it with each rotation, and then fatigue failure of the main shaft occurred in a very short period of time.

This research is about the quantitative evaluation method of cumulative fatigue damage by a constant acceleration-strain translation factor independent of the structural geometry in the fatigue evaluation of information board poles by acceleration measurement. The target is a gate-type information board, and an F-type information board. Since the translation factor used to convert the measured acceleration into strain is differs for each information board and requires measurement strain/acceleration or FEM analysis, in this research, to simplify the method, the constant translation factors are considered. The accuracy of evaluating the cumulative damage using the constant translation factor was compared with the accuracy of other evaluation methods. The constant translation factor method overestimated many target structures in the out of-plane direction. For case where the prediction error is large, it is considered necessary to set the translation factor depending on the level of the geometry based on the results of the FEM analysis.

ISO12100 provides a process of risk assessment and risk reduction (hereinafter referred to as RA/RR) to achieve the safety of machinery. This process shows a three-step method of inherently safe design measures, safeguarding and complementary protective measures, and information for use. It is specialized in how to introduce safety measures, so it is difficult to incorporate this method in the design process of machinery. The scheme design process consists of four stages: requirement specification definition, function definition, component and mechanism selection, and structural design. Classify the safety measures shown in ISO12100 by content, and appropriately allocate items to be considered in these four stages. Study at each stage is narrowed down and clarified by this task. By proceeding with this process, an appropriate design with few omissions is derived. With this proposal, a front-loading design process is implemented, and mechanical design acquires appropriate safe design measures.

Hybrid-rocket solid fuel grain with a star-fractal swirl port was developed in our previous study to improve the fuel regression rate. The effectiveness of this grain has been demonstrated by ground combustion experiments and ballistic launch experiments. However, its characteristic-exhaust-velocity (c^*) efficiency was insufficient, and the swirl geometry of the port caused roll torque in the fuselage. In order to improve c^* efficiency and reduce roll torque, hybrid-rocket solid fuel grain with a star-fractal counter-swirl port was developed here. Combustion experimental results showed that the developed grain improves the c^* efficiency and fuel regression rate. Numerical results using computational fluid dynamics suggested that a double vortex structure (inner clockwise flow and outer counterclockwise flow) may enhance the mixing of fuel gas and oxidizer and that, compared with the original swirl geometry of the port, the counter-swirl geometry decreases the exhausted circumferential momentum flow rate from the nozzle. This may also reduce roll torque.

Hybrid rockets often use a launch-stem system. However, this method has a problem that the timing of the main combustion cannot be properly controlled. We have developed a system in which a valve is mounted inside the rocket body and the main combustion is triggered by the opening of the valve. We also developed a mechanism to supply oxidizer from the side of the rocket and to disconnect the supply pipe. The performance of the system was confirmed through combustion and launch tests.

Although the number of small satellite launches and operations has been increasing year by year in recent years, the current situation is still dominated by the use of a shared launch vehicle, and launch methods specialized for small satellites have not yet been developed in earnest.

In this presentation, we will give an overview of our launch method, which is not a conventional rocket launch but an airborne launch using a commercial aircraft (Boeing 757). We also plan to offer microgravity flights using the same type of aircraft.

Downward flame spread over a Poly-methyl-methacrylate) (PMMA) sheet combined with copper (Cu) plate was investigated under constant oxygen concentration and various airflow velocities. Because they involve the heat conductivity of metals, composite materials' flame spread characteristics may differ from those of basic flammable plastics. In this experiment, the oxygen concentration of the mixture stream (O2 and N2) in the test section was 22 vol.%. Opposed-flow velocity in the test section changes between 20-100 cm/s. The flame spread rate and flame length decrease with the flow velocity increase. We changed flow velocity during the experiment from lower to higher velocity. The composite material showed a slightly higher flame spread rate compare to the basic PMMA sample.

A hybrid rocket kick motor is being developed for low-cost deep space exploration. Nytrox, a mixture of nitrous oxide (N₂O) and oxygen, will be investigated as an oxidizer for the kick motor. Nytrox has the advantage for use in kick motors of being safer than N₂O because it is less likely to cause decomposition reactions. The objective of this study is to obtain the fuel regression rate equation by conducting combustion tests to design a kick motor using Nytrox and high-density polyethylene (HDPE). The Nytrox used in this study was generated under conditions where the probability of N₂O decomposition reactions occurring was as low as possible. The fuel regression rate equation of Nytrox/HDPE was obtained from five combustion tests. Comparison with the fuel regression rate of N₂O /HDPE obtained from two combustion tests indicated that the fuel regression rate of Nytrox may be larger than that of N₂O, depending on the fuel. However, the number of experiments is small, and more data is needed to obtain accurate data.

In order to increase the opportunities for deep space exploration by small satellites, our laboratory has been working on developing a safe, high-thrust hybrid rocket motor. To obtain the thrust characteristics of the hybrid rocket under low-pressure conditions, the authors developed a HATS (High Altitude Test Stand) for small satellite thrusters that can maintain a low-pressure environment during combustion tests and found that the current combustion conditions and diffuser shape could not maintain a low-pressure environment. Therefore, this study designed and verified a new diffuser with a second throat in the middle of the diffuser to maintain a low-pressure environment. Using the two theoretical models presented in a previous study, we confirmed that there exists a design solution for a diffuser shape that can maintain a low-pressure environment under the current combustion conditions. Although the design solution is close to the lower limit of the second throat diameter, the design solution obtained from the theoretical model is not highly reliable because few previous studies experimentally investigated the lower limit. Therefore, the design solution was verified using a sub-scale diffuser and cold gas.

The objective of this study is to design and develop a hybrid rocket that is re-ignitable and does not require an igniter, focusing on the conductivity obtained by the addition of a large amount of carbon black. By conducting five and eight combustion tests using pure PLA fuel and conductive fuel with a large amount of carbon black added to PLA as solid fuel and gaseous oxygen as oxidizer, respectively, the fuel regression rate equations necessary for the proper design of hybrid rockets were established. The respective fuel regression rate equations were as follows (R² = 0.8154), Conductive fuel: (R² = 0.3975). Since the oxidizer index in the fuel regression rate equation exceeded 1 in the conductive fuel results, more data should be collected in the future to improve the equation.

We have fabricated and characterized a battery case containing a solidified phase change material (PCM) of tungsten-doped vanadium dioxide (VWO₂) as a heat storage material for a thermal control method for CubeSat electric power systems. Regarding the severe space and weight constraints for CubeSat implementation, we successfully fabricated the desired battery case by solidifying VWO₂, which undergoes a phase transition within the target temperature range, combining it with an epoxy resin to form a block, and processing it to accommodate commercial cylindrical 18650 lithium-ion cells. When the battery case containing the PCM was exposed to a temperature environment simulating Earth orbit, temperature measurements on the surface of the battery case confirmed that the phase transition of VWO₂ occurred within the desired temperature range during both cooling and heating, thus realizing a power source with high stability suitable for CubeSats.

Nitrous oxide is an attractive option as an oxidizer for rockets because of its self-pressurized supply and safety. On the other hand, it is very close to the critical point at room temperature, so the prediction of its state quantity requires very complicated calculations. Prediction of the oxidizer flow rate is important for hybrid rockets, and various prediction equations have been proposed. In particular, the Homogeneous Non-Equilibrium Flow Model, which assumes that the mass flow rate of nitrous oxide takes a value between liquid single-phase flow and gas-liquid two-phase flow, is considered to be accurate. However, this HNE flow model does not consider the effect of injector geometry, and the authors proposed a new model, HNEIS, which considers injector geometry. From flow rate tests using several injectors with different geometries, it was found that the flow rate varies depending on the injector geometry even when the supply pressure is equal. It was also clear that the HNEIS could express this trend, whereas the HNE could not. On the other hand, there is a dissociation between the actual flow rate and the predicted flow rate by HNEIS, and the model needs to be improved.

Space vehicles are subjected to significant aerodynamic heating during reentry into the Earth's atmosphere. In recent years, silicon-based materials have attracted attention as innovative thermal protection materials, and this laboratory has focused on silicon carbide and systematically conducted heating experiments using high-temperature air plasmajets. In this study, the heating behavior of silicon carbide was observed spatially and temporally using a wide dynamic range camera. In particular, we paid attention to the weak radiation around the test piece and investigated the spatial and temporal distributions of the radiation and the mechanism leading to the radiation.

Telecommunication between an atmospheric entry vehicle and the grand station can be interrupted by a high-density plasma caused by aerodynamic heating called a communication blackout. Plasma attenuates the electromagnetic waves for telecommunication, making it impossible to obtain the positioning information and the observation data. Reduction of the density of the electron density around the vehicle is important to mitigate the communication blackout. In this study, we focused on a thin air film layer formed by gas injection as a mitigation method of communication blackout during atmospheric reentry. The arc-heated wind tunnel experiment was numerically reproduced based on computational fluid dynamics (CFD). Plasma density was low in the air film layer. The cold gas formed the propagation path of the communication wave. We also performed a gas injection experiment to observe the jet shape by Schlieren imaging. It revealed the density distribution around the injection outlet. It was found that the shock wave formed in front of the jet. Comparing the Schlieren photography with the CFD results shows qualitative agreement. Therefore, numerical analysis and wind tunnel tests both show that the plasma can be moved away from the surface by injecting cold gas in a high enthalpy airflow.

The atmospheric entry velocity becomes 15 km/s in a deep space sample return mission. A new aerodynamic shape capsule with a lightweight and large-area thin shell aeroshell that decelerates from higher altitude with a low ballistic coefficient has been proposed. This deep space sample return capsule (DS-SRC) is designed to return without a parachute, which is highly demanded to be stable at all speeds. In July 2022, a free flight experiment (Rubber balloon experiment for reentry capsule with thin aeroshell: RERA) in the low-speed region using a rubber balloon was conducted for DS-SRC to investigate aerodynamic characteristics and dynamic attitude instability. In this study, two kinds of static CFD simulations of the low-speed free flight environment from the angle of attack 0° to 25° were conducted to obtain the relationship between angle of attack and drag coefficient, and to obtain the flow field that was not directly measured in the experiments. RANS results showed good agreement with the flight data. These insights are expected to help to clarify its aerodynamic characteristics and dynamic posture instability.

In 2022, Japan's Civil Aeronautics Law will be amended to make aircraft (flying objects) weighing 100 g or more subject to the Civil Aeronautics Law, making it difficult for students to actually fly drones and airplanes to experience the mechanics of flight in an educational setting. On the other hand, “Takebombo” do not have a motor and are outside the scope of the Civil Aeronautics Law, as they weigh only a few grams or less, making it possible for students to experience flight in a familiar way. In this study, we describe an attempt to develop a "launch pad" that can objectively measure the flight performance of not only a bamboo-copter (= ”Takebombo” ) and 3D printed PLA-copter but also a paper-copter, which can be easily made from paper.

The video explaining process cooking caramel sauce by heating sugar on a pan also introduces water vaporization and organic chemistry. The video is streamed by YouTube channel of Oita University, and the content of the video should be understand by common Japanese. The reason the video treats cooking to introduce science and engineering, cooking is much more popular than handicraft, and cooking also relate with engineering and science. Now, in Japan, it is not popular to make some craftworks except for job or task. Caramelization, which cause bitter taste, requires heating sugar after water vaporization, and is irreversible. Rapid cooling is required by not only caramel sauce also pan. Latent heat helps the rapid cooling. Water vaporization for caramel sauce increases both viscosity and concentration of the caramel sauce. This increase of both viscosity and concentration of the caramel sauce is reversible. Water supply into the caramel sauce of which viscosity is too high decreases the viscosity.

Since 2020, STEAM education has been spreading in Japan. In order to promote STEAM education, digital fabrication workshops are necessary. The author set up a workshop in the university based on the standard equipment of Fablab, which are citizens' workshops for digital manufacturing that spread around the world. Based on these efforts, we propose a digital fabrication workshop to be installed mainly in ordinary high schools. The workshop is equipped with digital fabrication equipment, wood processing, metal processing, electronic work, etc. Except for expensive laser cutter, you can install them for 1 million yen. We hope that the establishment of Digifab workshops will spread to high schools.

We are trying to analyze videos taken with smartphones and use them to understand physical phenomena. In this report, we introduce a method to measure the moment of inertia of a circular object by rolling it on a slope. It was clarified that the influence of rolling resistance can be offset by reciprocating the slope, and the measurement accuracy is improved.

Low Temperature Difference Stirling Engine (LTDSE) is an excellent teaching material for mechanical design. However, it is not easy to construct a working engine due to its low specific power. In order to make LTESE more effective teaching materials, this paper describes the design and fabrication of a LTDSE with high specific power that can run at higher speed. The results of analyzing the working fluid temperatures in the expansion and compression spaces indicate that the temperature ratio increases with increasing speed even in LTDSE. We found that an arrayed plastic regenerator can provide high performance. Compared with other LTDSEs in terms of specific power, which is defined by the product of Beale number and rotational speed, the specific power of the test engine is more than 10 times higher and the rotational speed is nearly three times higher than those of previous LTDSEs. The results show that LTDSE with higher specific power can be designed and fabricated by using 3D printers, and the value of LTDSE as a teaching material has been enhanced.

At the Toyota Commemorative Museum of Industry and Technology, many of the machine tools that Kiichiro Toyoda used when he started the automobile factory in 1938 are on display. One of them, a 1939 G&H hobbing machine, was investigated and found that the motor was manufactured by Fuji Electric in 1924. The details of this motor are currently under investigation, and inside it used bearings manufactured by SKF in the early 1920s. Upon detailed investigation of this bearing, it became clear that the precision and materials were already comparable to modern bearings, and that in Europe in the early 1920s, bearing manufacturing technology that could be used today had been established.

Toyoda Power Loom, Type N is the wide and heavy power loom invented by Sakichi TOYODA in 1914.

Sakichi TOYODA had developed the Power Loom, Type N that incorporates mechanisms other than the Automatic Shuttle Changing Mechanism, such as a strong frame structure and a Positive Warp Let-off Mechanism, in the process of completing his ultimate goal, the Non-stop Shuttle-change Automatic Loom, Type G. This loom is the base of the Automatic loom, Type G.

The Power Loom, Type N is still used today for thick fabrics such as Japanese Traditional Aprons. It will be reported on the structure, mechanism, usability, etc. of this Power Loom, Type N.

Foreign ships came into the territorial seas in the late Edo period forced the shogunate to revitalize the general plan for defending the country. Defending with cannons was planned as a strategic choice and manufacturing of cannons was promoted using the technology in that period. Material processing especially related to the manufacturing of cannons has already been studied in the series of research on material processing and manufacturing in that period. Structures were required by cannons deployed against the foreign ships. Those structures were mainly batteries called Daiba, including other fortifications. They were constructed on the sea and by the seashore all over the country. Components and system for defense are incorporated into the structures for defense and larger structures are composed based on their components and system. The aim of this paper is to research how the components of the structures for defense by deploying cannons had been designed.

The Alternative ☆ Energy Contest was launched in 2008 as the new energy utilization contest for students of universities and National Institute of Technologies, which was held in collaboration with Technology and Society Division, The Japan Society of Mechanical Engineers. In this report, the number of applications, participants and sponsoring companies were investigated in the 13th Alternative ☆ Energy Contest held at College of Engineering, Nihon University on Saturday, October 15, 2022. In addition, we classified the energy sources and energy conversions in the presentation.

With the aim of promoting the introduction of renewable energy and fostering human resources in Fukushima Prefecture, the Ministry of the Environment utilized the "Collaborative Training Program for Regional Renewable Energy Promotion and Core Human Resource Development in Partnership with Educational Institutions." As part of this program, participants conducted a field visit to renewable energy facilities in Fukushima Prefecture. Additionally, lectures on case studies of renewable energy initiatives in the prefecture, group discussions, and surveys were conducted to deepen the understanding of renewable energy utilization methods. As a final outcome, the participating students proposed ideas for the utilization of renewable energy in Fukushima.

In recent years, marine renewable energy has been attracting attention among renewable energy sources, and research and development of tidal turbine has been progressing. Tidal turbine must be fixed to the seafloor because they generate regenerative torque in proportion to the amount of power generated. This makes construct and maintenance costs high, which is a problem. This research aims to develop a floating tidal turbine. The main feature of this system is that the generator is not fixed to a foundation in the sea, but is moored with a single wire, and two sets of turbines reverse on the same axis to offset the regenerative torque, there by controlling the attitude in the water. We believe that this will solve the problems of tidal turbine without the cost of construct and easy maintenance. To confirm whether the regenerative torque cancels out on land, an experimental device with a coaxial reversing mechanism was developed and used to measure the regenerative torque. The developed experimental apparatus has two rotors on the same axis, and eight magnets are attached to each rotor. Six coils are attached to the stator around the outer circumference of the two rotors, and the two rotors can be inverted on the same axis. Using this experimental apparatus, power generation experiments and regenerative torque measurement experiments were conducted by commutating three-phase alternating current. As a result, three-phase power generation was confirmed and the offset of the regenerative torque was also confirmed.

CO₂ hydrate (CH) has attracted attention as a technology that contributes to the realization of a sustainable society, such as desalination of seawater and CO₂ capture from combustion gases. According to a previous study, adding cyclopentane (CP) under unstirred conditions shortened the time from the start of cooling to the start of CH formation. However, we do not know why this phenomenon occurs due to the lack of direct visualization of the formation site. Therefore, in this study, an acrylic plate was used to create a visualization device that makes the formation field visible. This study aims to clarify the hypothesis that natural convection interaction between water and CP facilitates CO₂ dissolution. This apparatus measured the temporal variation of natural convection in the water-CP system during the cooling process by particle image velocimetry (PIV). The following results were obtained from this study: the direction of circulation of water convection during the cooling process was switched by PIV and the flow velocity was measured; the flow velocity of CP during the cooling process was measured by PIV; the flow velocity of CP during the cooling process was measured by PIV; the flow velocity of CP during the cooling process was measured by PIV. In the waterCP system, it was found that tracer particles accumulated at the interface, which interfered with the measurement by PIV.

This study examines a system configuration for supplying electricity and heat to Hakodate City from offshore and onshore wind power in the southern Hokkaido region, which is planned to achieve carbon neutrality by 2050. In the proposed system, electricity output from offshore and onshore wind farms is transmitted to a substation near Hakodate via a transmission line. The transmitted power is matched to the power load at the substation and supplied through the transmission line. Surplus power generated during this process is stored in storage batteries and hydrogen. When the power supply is insufficient, the power from the storage batteries and hydrogen gas are used to stabilize the power supply using fuel cells. This system can provide more than 90 % of Hakodate's annual electricity and heat needs. However, it is important to reduce the storage battery capacity in order to reduce costs. As a result, we believe that reducing the storage battery capacity and increasing the hydrogen tank capacity by prioritizing the use of electricity stored in the storage batteries will result in a system with low costs and a high ratio of electricity and heat supply to Hakodate. The supply ratio exceeds 90% when the storage battery ratio is 10 % or more, and the maximum supply ratio is reached when the storage battery ratio is around 25 %.

Mankind has achieved remarkable social development following the Industrial Revolution. Then, we have depended on fossil fuels for much of its energy needs. As a result, a global warming caused by the massive consumption of fossil fuels has recently come up to the surface. And the number of natural disasters caused by it is on the increase. In this background, a Stirling engine has attracted attention because of an ability to utilize a wide variety of heat source which were previously unused.

The goal of this research is the operating a Stirling engine by using low-temperature heat source such as snow and ice. We aimed at improvement in a running performance by cooling the cooler of a Stirling engine uniformly in this experiment. Therefore, we manufactured the water jacket newly and ran a coolant. By cooling a cooler uniformly, a Stirling engine using low temperature heat source worked long time. Furthermore, we introduce the power generation method “Triboelectric Nanogenerator” using the small torque of a Stirling engine in this report.

The fossil fuel prices are soaring due to the increased demand accompanying the recovery of the global economy from the Corona disaster. Furthermore, the value of Japanese Yen was decreasing to a lowest level in Japan last year. For that reason, the weak Yen spurred the soaring of fuel prices. Therefore, in order to realize a stable energy supply and a sustainable society, the technology for effectively utilizing the waste heat of low-temperature emitted from factories and power plants etc. is drawing attention.

The thermoelectric power generation is one of the technologies for generation using low-temperature exhaust heat. The thermoelectric power generation system requires a high-temperature heat source and a low-temperature heat source at both sides of a thermoelectric conversion elements (TCE). In practical use, it is desirable that the fluctuation of the high-temperature side heat source temperature is small.

In this research, we propose a thermoelectric power generation system that can effectively use an intermittent heat source temperature by using a latent heat thermal energy storage (LHTES) technology. A heat exchanger containing a mannitol-water mixture as a latent heat storage material, which is a phase change material (PCM), is placed on the heat absorption side of the thermoelectric conversion element. We clarified that the stable power generation can be obtained by using the latent heat storage material as mentioned above even when the heat source temperature changes.

The authors belong to National Institute of Technology, Yuge Collage, which is located on a remote island in the Seto Inland Sea. Such as in this remote island area, where resources are scarce, "bamboo cascade utilization," in which bamboo harvested from abandoned bamboo forests is used in stages, is considered effective. In this report, students conducted an integrated process of making a simple bamboo house from bamboo culms, producing bamboo charcoal for secondary use, and utilizing the bamboo charcoal to remove microplastics from the ocean. This project has spread as "remote island engineering," contributing to engineering education.

Instrumentation engineering is a cross-disciplinary subject that combines natural sciences with mechanical engineering, electronic, electrical and computer science. The class deals with topics such as the statistical processing and the least squares method that deepen students' understanding by repeating exercises, whereas it also deals with working principle of various measuring instruments. Due to the wide range of topics, changing the class structure and materials in each class can be effective to improve the students' understanding. This paper discusses continuous improvement of lecture in instrumentation engineering by referring to student questionnaire results. Specifically, we focus on topics that students evaluated as “most understandable” and “least understandable”. The results indicate that the students want well-balanced classes of explanation, writing on the blackboard, and exercise. Organizing classes suitable for each unit while being aware of the student's objective is required.

Fukuoka University provides a place for craftsmanship with rockets as the theme. The purpose is to provide a place to practice the knowledge and skills learned in classroom lectures, support students' independent manufacturing activities, develop space transportation engineers, and provide an environment where they can feel the connection with society. A feature of this program is that test flights and trial runs are not possible. Students need to imagine potential troubles for each development item and perform quantitative evaluation and solutions through tests. About 5 to 10 people are required, and management as a team is essential. For rocket engine combustion experiments and rocket launch experiments, it is necessary to summarize, explain, and obtain permission from the local government and residents who manage the test site for safety and security. Students are expected to acquire negotiating skills by thinking about how to connect with society and how to explain and convince them of what they want to do. By summarizing the quantitative evaluation and its validity on the document, it is expected that the writing ability and information transmission ability will be improved. From the results of the questionnaire, about 70% of the graduates answered that they would use what they experienced and learned in this activity in their work. It is thought that the teacher's support for project management and schedule management methods will lead to a higher degree of satisfaction.

In order to guarantee the quality of education, it is important to form the identity for engineer. This may be prompted by the student self-change. It may be promoted by the conceptual change. In particular, productive thinking grows through conceptual change according to the needs of society. This thinking is easier to grow when self-efficacy is high. In order to do so, it is necessary to have the communication ability to satisfy the approval request. By communicating, students will study in area with high educational effects in the learning pyramid. It is the first step toward self-determination learning that is required when students work or do research. However, in order for approval demands to arise, it is necessary to meet social demands one step lower and safety requirements even lower on Maslow's five-step requirements. By satisfying these requirements, self-actualization demands are born, and students are satisfied with the results they have created and begin to enjoy learning. This result is exactly what the graduate is learning, and guidance is necessary to encourage them to continue for the duration of their enrollment.

In a water channel as an internal flow, the velocity is increasing in where the cross-sectional area is small according to Bernoulli's law. Because of this strong impression, many students of KOSEN misunderstand that the specific energy of flow through a channel with a wide cross-section area on the upstream side is larger than that of it through a channel with a wide cross-sectional area on the downstream side in the internal/external mixed flow.

In this report, the cause of such misunderstandings of the beginners on fluid dynamics or hydraulics is considered through a simple model experiment using an open typed undershot water wheel.

In Japanese art education up to high school, there is no education on theory and exercise to accurately write the shape on the plane. Moreover, with the popularization of smartphones with cameras, the ability of university students at hand drawings has declined. Then the conventional curriculum of the mechanical drawing, teaching of drafting rules, cannot improve their drafting technic and the ability to imagine 3D object from 2D drawing. We have developed a new curriculum to develop their ability described in above before the study of drafting rules. Theories and exercises on projection geometry and isometric drawing are studied in the new curriculum “Fundamental Drawing”. Most of students have drawn well the isometric drawing of a squill vise from the given figure information in third angle system at the end of total 18 hours lectures.

We have developed the computer assisted instruction system for technical drawing education, which generates three-dimensional (3D) models from handwritten projection drawings with reflecting errors. In this study, the hidden line handling function was newly implemented. Lines written in the projection drawing captured with a smartphone were converted into simple zigzag lines with distinct vertices using the Ramer-Douglas-Pecker algorithm and described as the graphical structure whose nodes correspond to the coordinates of the vertices of the projected figure. The visible outlines that make up the projected figure were identified based on the connection attributes at the nodes in the graph, in which case the number of nodes of the subgraph that are part of the visible outlines will be greater. On the other hand, the hidden lines were extracted from the group of short lines using the Hough transform. After these processes, the ridge lines of the 3D model were determined by checking the consistency between the corresponding points and sides in a couple of projections. Finally, imaginary surfaces were excluded by examining the conflict between visible and invisible planes, and the 3D model was generated. The usefulness for self-learning of technical drawing was demonstrated by running examples of the developed system for the case of drawings with hidden lines.

Recently, PBL (Problem/Program Based Learning) is very important subject in university and college education. In the PBL subject with manufacturing components, computer numerical control (CNC) machine tools is useful than general-purpose machine tools. In this study, we developed a procedure manual of operating CO₂ laser cutting/engraving machine with open source 3D modeler for manufacturing activity basics in PBL subject. On the other hand, CNC machine such as laser cutting/engraving machine and topology optimization have a high affinity for each other. Accordingly, we showed a procedure manual of open ring pull can opener gadget topology optimization with base-model for the college of technology second grade students, who not yet learned Strength of Materials and Computer Aided Engineering (CAE) / Finite Element Analysis (FEA).

Education of environmental energy and engineering technology for children, who will lead the next generation, is very important to realize a decarbonized society for the future and to achieve the Sustainable Development Goals (SDGs). The author has been devising a novel educational method that incorporates a problem-solving game (quizzes, puzzles, etc.) and has been energetically developing educational materials and practicing the educational method. This report describes the development and educational practice of an original educational material for children that enables them to enjoy learning about hydrogen energy through experience by incorporating the problem-solving game. This educational material not only allows children to solve problems, but also to deepen their understanding of the learning theme by combining handicrafts, experiments, and other activities. The results of questionnaire surveys after the educational practice showed that the teaching materials were highly evaluated by the children who participated in the practice.

In the education of skill accompanied by physical movements within manufacturing companies, there is generally a defined level of proficiency that should be acquired. Consequently, the evaluation of each educational process is predominantly based on the criteria set by the instructors. While the assessment of knowledge acquisition in formal subjects aligns closely with the evaluation conducted by instructors, when it comes to physical skills, differences in individuals' somatic senses due to bodily characteristics and motor experiences are expected to be significant. In other words, the disparity between the evaluations of instructors and learners' respective physical abilities is presumed to significantly influence the shared understanding of information related to physical skill education. Therefore, this study aims to investigate the impact of empathy on this shared understanding and seeks to develop effective techniques for skill education.

With the goal of automating the task of analyzing rugby games, we worked on machine learning to extract ruck scenes from match videos. A general-purpose video machine learning tool called YOLOv5 was used to perform the machine learning. Inference results were evaluated by Accuracy, Precision, Recall, and F-measure indices in an inference test with approximately 10 minutes of match video input. The machine learning program in this paper provides a direction for future efforts toward the practical application of automated analysis tasks.

The objective of this study is to measure the hand motion during tremolo playing on mandolin and evaluate how the movements vary based on skill level and playing style. The test subjects consisted five mandolin players with varying years of experience. Hand motions were measured using an inertial sensor placed on the back of the right hand, which held a pick. Subjects played tremolo on each of the four strings in five styles: neutral, fast, slow, forte, and piano. The targeted parameters were the angular velocities around the distal and dorsal axes. The phase lag between these axes was considered as the characteristic of the motion. Each angular velocity was bandwidth filtered and time-integrated, and the ratio of the ranges of each axis was also considered as a characteristic. As a result, the variation of the motions became larger for different styles of the tremolo by being skilled, while individual differences decreased. It was suggested that as skills improve, individual differences decreased due to approaching an ideal motion, and players developed expressiveness through variations in their motion. However, due to the limited number of test subjects, it remains unclear whether these findings represent a general characteristic.

Because lower extremity muscle forces and muscle activities involved in gait are closely related to stiffness of flooring material, development of flooring material which can suppress loads on the lower extremities is necessary. We have developed an elastic pavement material which is made of 3D network structured fiber material with the aim of decreasing loads, and it is necessary to assess its suppression effects on loads mechanically. In this study, we obtained gait motions of 7 subjects on the elastic pavement material and on normal flooring, performed musculoskeletal simulation and compared joint reaction forces and muscle activities involved in gaits between the flooring types. The results show that the maximum values of joint reaction forces and muscle activities of the gait on the elastic pavement material were smaller. These could be derived from the change in walking posture and kicking conditions due to the flexibility of the elastic pavement material, and also corresponded to our previous results of a sensory evaluation. The results suggest that the elastic pavement material can suppress loads on the lower extremities during walking. Furthermore, and effectiveness of musculoskeletal simulation for assessment of loads during walking was demonstrated.

There are two types of personality test methods in common use: verbal and non-verbal, each with its advantages and disadvantages. If a new personality test method that can compensate for the disadvantages of both methods is developed, it would be used worldwide. To develop a new method to estimate human personality, we have attempted to measure human motions using the optical motion capture system (OMC) and group them by feature points. However, it was found that OMC is inconvenient due to camera calibration and attachment of infrared markers to subjects. In this paper, to make it more efficient, we compared OpenPose, which can detect the position of human joints with a video camera, to OMC. As a result, it was confirmed that OpenPose is more effective than OMC in analyzing human motion. In addition, we attempted transfer learning for classifying test scores of a personality test based on “Big Five personality traits” from walking trajectory graphs from OpenPose.

In recent years, the population of farmers has been declining. Therefore, there is a demand for lighter and more efficient farm work, and larger farm machinery is becoming more widely used. Since these farm machines inevitably require getting in and out of the machine, there is a need to reduce the physical burden of getting in and out of the machine. Therefore, it is necessary to quantitatively evaluate the physical burden of getting on and off the machines. In this study, we focused on tractors, which have a high penetration rate among agricultural machinery, and calculated the physical burden to determine the ease of getting on and off the tractor. Using a musculoskeletal model that simulates human movement, information on the body burden, such as muscle strength, is calculated from the movement data, and an evaluation index of the body burden is created. Using these indices, we examined the effects of changing factors such as tractor entrance width and grip position on the body burden.

Wind tunnel tests are commonly used to determine aerodynamic characteristics. However, the flight of a soccer ball is under unsteady conditions with acceleration and deceleration. Therefore, in this study we discussed a method for estimating the aerodynamic coefficient of a soccer ball from moment to moment. The method uses a genetic algorithm to determine the aerodynamic coefficients at multiple control points on the time axis as design variables. The genetic algorithm is an optimization method that mimics biological evolution. The time function of the aerodynamic coefficient is expressed by connecting the control points with a cubic spline. The objective of this study is to find a time function of the aerodynamic coefficients that minimizes the objective functions (1) sum of trajectory differences, (2) sum of flight path differences, and (3) sum of speed differences using the genetic algorithm. The estimated time functions of the aerodynamic coefficients and trajectories were almost consistent.