We researched and developed a method to evaluate the presence or absence of the harmful defect of the type 2 pressure vessel in non-open operation and non-destructive by applying the acoustic emission (AE) measurement technologies. As an alternative to the conventional open inspection for hydrogen station accumulators, it is expected that the safety response of hydrogen-related businesses will be optimized. Regarding the in-service inspection method based on the results of this R&D project in NEDO for the duration spanning fiscal years 2018 to 2022, a private standard (Japanese Society for Nondestructive Testing Standards, NDIS) was established in October 2023.

Machine learning and generative AI were performed to flow fields generation and aerodynamic noise estimation for optimization of fan design. CNN is suitable for design optimization, and the estimation results using machine learning data based on 2D airfoil data show the same trend as actual fan performance. It reveals that fan performance evaluation using machine learning can contribute to reducing analysis data and design time. The results show that fan performance evaluation using machine learning can contribute to reducing analysis data and design time. When estimating aerodynamic noise based on flow field information using generative AI, it was found that if the data is reduced too much, the estimation accuracy is not sufficient, as small changes in the flow field are important. Under the conditions of this study, the latent variable vector for the generated AI was rather large 64. It was found that care should be taken with the size of the collapsed data when estimating images and when estimating physical phenomena such as aerodynamic noise.

Regarding aerodynamic self-excited tone accompanied by acoustic resonance generated from a semi-cylindrical cavity, we estimated characteristics of the secondary flow inside the cavity based on the results of acoustic mode numerical analysis, the already measured distribution of flow velocity turbulence and the flow pattern as results of flow-visualization. Resonant mode which is similar as the flow pattern could be found through acoustic analysis although the resonant frequency is higher than measured tone frequency. This mode consists of one antinode in radial direction and four antinodes in circumferential direction. And we have considered the mechanism of vortex shedding on open edge of the cavity during resonance. It was inferred that the secondary flow, which becomes stronger in the antinode region of the sound pressure distribution due to resonance, influences the periodicity of vortex shedding. It would be the remaining subject to make clear the difference of the resonant frequency between experimentally measured and numerical analyzed.

Resonant acoustic liners for noise reduction in aircraft jet engines consist of several small liner elements. These elements interfere with each other acoustically and exhibit complex behavior. In addition, the grazing flow also affects the acoustic characteristics. A one-dimensional duct acoustic analysis similar to the transfer matrix method was attempted for this phenomenon, and the results simulated the experimental results well. This indicates that once the characteristics of one resonator are obtained, the characteristics of the entire acoustic liner with multiple resonators in a row can be estimated with a simple calculation. This method may also provide a clue to understanding why and how the impedance of acoustic liners changes with grazing flow.

A perforated metal plate has many small holes. High-speed air flow through the perforated metal plate generates noise caused by aerodynamic vibration or plate vibration. This study deals with the suppression of the noise caused by the high-speed air flow through the perforated metal plate. The expansion type perforated metal plate with plover hole position generated a large level noise with a prominent peak. In the flow visualization experiment, the jet flow in-phase interference is important for the generation of a prominent noise peak is found. Each hole distance is required to change the aperiodicity to suppress the jet flow interference. Aperiodic tiling is used to determine the hole position of the perforated metal plate to make the aperiodic perforated metal plate. However, the aperiodic perforated metal plate could not suppress the prominent noise peak. It is found that the jet flow interference is not important for the prominent noise peak.

The present paper focuses on the effect of tapered orifices and flow on the acoustic absorption performance of perforated plate. We experimentally measured the flow velocity, acoustic pressure, and transfer function using the improved acoustic impedance tube. The normal incidence absorption coefficient was calculated from the measured transfer function using transfer function methods. The peak frequency of the acoustic absorption coefficient depended on the taper angle of the holes of the perforated plate. The peak frequency of the sound absorption coefficient frequency response increases with tapered orifices. Acoustic resistance does not change as the taper angle changes, but acoustic reactance changes as the taper angle increases. The acoustic reactance will be nearly the same whether the orifice tapers upstream or downstream. We discussed the effect of the taper orifices and flow on the specific acoustic performance.

In recent years, there has been a heightened awareness of so-called low-frequency sound below about 100 Hz as a social issue. Although the most useful countermeasure for low-frequency sound is considered to be a sound source countermeasure, it is not always easy to implement. In this study, we focused on the so-called “house countermeasures” that can be implemented inside a house where low-frequency sounds enter the room. We experimentally investigated how much sound at 100 Hz could be reduced by installing sound absorbers in a room, using a test building. Prototypes of sound absorbers with three different sound absorption mechanisms were tested. As a result, it was confirmed that the sound pressure level in the room was reduced by several dB to 10 dB for all the absorbers. This paper provides an overview of the experiments and the characteristics of the three types of sound absorbers.

In recent years, there has been a heightened social awareness of the problem of so-called low-frequency sound below approximately 100 Hz. The most effective countermeasure against low-frequency sound is considered to be a sound source countermeasure, but its implementation is not always easy. Therefore, this study focused on so-called ‘indoor countermeasures’ that can be implemented inside the house where low-frequency sound enters the room. An experimental building was used to verify the possibility of reducing 100 Hz sound to a certain level by installing sound-absorbing materials inside the room. In this report, a prototype wooden sound absorber, which can be made by DIY, made of perforated board with a back air cavity, was tested. As a result, it was confirmed that the sound pressure level in the room was reduced by about 10 dB on average, suggesting the possibility of measures to reduce low-frequency sound in the house.

A study was conducted using COMSOL Multiphysics analysis software to investigate a method for reducing low-frequency noise incident on residential houses. A restriction has been placed on the depth of installed devices to be within 300mm. As a solution, we proposed a device made by folded resonator with quarter-wavelength. The device is fabricated from cardboard, and it is applied to a field test using a simulated house. Noise reduction performance is investigated by measuring the three-dimensional sound pressure distribution in the room. The results show that the installation of the device significantly changes the sound pressure distribution in the room and, in particular, suppresses the increase in sound pressure at all corners of the room. The average sound pressure level on the floor can be reduced by up to 5 dB.

At recently, under 200Hz sound noise becomes social problem because appropriate measures are implemented under middle frequency sound noise. For this reason, we verify attenuation effect of plate type sound absorber inside imitated house with 100Hz sound noise over window. And we verify that four corner arrangement inside room attenuate the room mode (1-1-0), and attenuation level of floor are around 6 dB.

There is a vibration speaker device called an audio exciter. The potential of the exciter as a vibration device was investigated by conducting experiments on a single steel plate and comparing the results with the impact test method using an impulse hammer. The power spectrum results showed that the exciter was able to vibrate up to approximately 20 kHz, and it was shown that it was possible to predict the magnitude of the exciter's FRF from the impulse hammer FRF results. Furthermore, a comparison with the impulse hammer results showed that the ILF identification was qualitatively better.

In this study, we analyzed radiated noise increasing factor of an industrial sewing machine using transfer path analysis method. At first, A-weighted sound pressure level of an industrial sewing machine radiated noise was measured and the radiated noise was found to be large at 400 Hz band when the sewing machine was operated at 5000 spm. Subsequently, the high contributing principal component vibration behavior of the sewing machine was analyzed by applying operational transfer path analysis (OTPA) principal component model. The result showed that the behavior in which arm tip of the body vibrates largely was the main factor increasing the noise. In addition, for identifying main input force to the high contributing vibration behavior of the sewing machine, blocked force from rotating shaft bearings to the body at several points were estimated and the contribution from each blocked force to the high contributing vibration behavior was obtained using OTPA reference model. As the result, the input force from bearing to the arm tip point along up-down direction was found to excite the high contributing vibration behavior. From these results, the main factors increasing the radiated noise of the industrial sewing machine were identified.

Hydrogen is being considered as a solution to decarbonize aviation propulsion systems. However, the faster combustion rate of hydrogen-based gas turbine combustors compared to existing jet-fueled gas turbine combustors may result in higher combustion vibrations. Therefore, it is important to take measures against vibration and acoustics, such as ensuring that the natural frequencies of vibration and acoustics are not matched. In this study, an acoustic finite element (FEM) analysis model simulating a combustor element test rig designed to enable a small gas turbine engine to be fired by hydrogen is first presented. The dominant acoustic modes are identified from the analysis results. Finally, for noise reduction in the combustor, a sound absorbing liner is designed based on the theoretical equation and the reduction effect of the sound absorbing liner is described by acoustic FEM analysis.

Reduction in aerodynamic noise emitted from a pantograph is an important subject for reducing environmental impact of high-speed trains. In the previous study, aerodynamic noise reduction method of pantograph head support by applying perforated plates to ridge corners was proposed. In this study, relation between inner and outer shape of perforated plates and aerodynamic noise reduction effect is investigated. From a wind tunnel test result, it is clarified that setting appropriate inner and outer shape of perforated plates can reduce aerodynamic noise to the same extent as applying porous material.

Aerodynamic noise emitted from a pantograph is a major source of noise in the course of Shinkansen operation, as aerodynamic noise increases proportionately to the sixth power of the train’s speed. To reduce pantograph noise on Shinkansen trains, we have developed low-noise pantographs and pantograph noise-insulation plates with more effective shapes in the past. In this study, the installation of sound-absorbing materials for pantograph noise-insulation plates and roof covers to further reduce pantograph noise was tested with a mock-up. In addition, we conducted running tests using a Shinkansen high-speed test train and confirmed that pantograph peak noise level can be reduced by more than 1dB when applying sound-absorbing materials.

Abnormal sound generated during vehicle running situation is one of the important information for driving safety, hence the inspection is generally carried out at the final stage of vehicle manufacturing inspection process. For the reduction of the inspectors’ load and carrying out stable inspection, automatic abnormal sound inspection method is essential. On the other hand, there are various kinds of standard noise generated at the situation such as road noise in case an abnormal sound is generated at general driving condition. In this situation, detecting the abnormal sound becomes difficult. In this study, an automatic abnormal sound detection method using two (left and right side) microphones in noisy condition is proposed. In the method, one of two microphones is used for the reduction of the standard noise and existence of abnormal sound is evaluated by using similarity of a lot of noise decreased sounds. In addition, an estimation method for indicating the abnormal sound direction is also considered by comparing the standard noise decreased sound at left and right side in case the abnormal sound is detected.

This study proposes a method to consider microphone array configuration for drone collision avoidance based on amplitude modulation(AM) of helicopter motion sound. As the number of microphones in the array increases, magnitude of modulation becomes larger and half width becomes narrower. Although the combination of these two factors has a great influence on the detection of helicopter motion sound, it is not known how to combine them to form a microphone array suitable for the detection of helicopter motion sound. Therefore, we consider a specific method to optimize microphone array. First, determination of the number of microphone arrays. Assume that microphone is attached to each arm of the drone. Therefore, the number of microphone arrays is equal to the number of drone arms. Second, we calculate desired microphone array directivity as half width. Third, from the prior data calculated for the number of microphones and half width and magnitude of modulation, obtain the number of microphones for each microphone spacing satisfying the conditions. Finally, the point where magnitude of modulation is the largest and the number of microphones is the smallest is obtained as the number of microphones. By following the above procedure, we can find microphone arrays suitable for detecting helicopter motion sound. From the simulation results, it is found that 6 microphone arrays, 34 microphones, 0.02 m microphone spacing, and 0.66 m microphone array length is suitable for the detection of helicopter.

Ducts are widely used in an industry field. For example, a high-power suction truck has a complex piping system which starts from a root blower to a final exit while repeating bend. The root blower generates a large pulsation and make resonance with the piping system. In order to avoid the resonance, it is necessary to know the natural acoustic frequency of the piping system．We already reported on the resonant frequency of sound fields in ducts with different diameters. This paper investigates the noise damping effects of bending in ducts with multiple bends. Additionally, the noise damping effects of inserting sound-absorbing materials into the duct were also examined. Through experiments and analysis, the frequencies at which damping effects occur were identified. Furthermore, it became clear that the frequencies at which damping effects occur vary depending on the inner diameter of the duct.

The directional detection of sound sources using frequency modulation generated by radiated sound from moving sound sources has been investigated. It has been shown that direction detection is possible when there is no acoustic phenomenon such as reflection and diffraction. In a sound field where barriers exist on the propagation path of the radiated sound, it is difficult to detect the direction of a moving sound source. Numerical simulation can be used to analyze such sound field characteristics. In this paper, we investigate the possibility of detecting the direction of a sound source in a space where barrier is placed on the propagation path of sound generated by a moving sound source. When the sound source is visible from the observation point, the direction of the sound source is detected. Otherwise, the direction of the edge of the barrier, which is the diffraction point, is detected.

This paper deals with the problem of separating a single broadband sound into audible and inaudible zones in the same space. In a previous study, a method for designing a control filter to control a broadband sound was proposed. However, the frequency response of the control filter obtained by ACC is not optimal, since it is only a simple arrangement of the sound source outputs obtained independently at each frequency. Therefore, we focused on the frequency response of the amplitude of the control filter and introduced the amplitude coefficient that would determine the relevance of each frequency. This is determined by specifying one control point in the audible zone and calculating the ratio between the signal without control and the signal obtained by ACC at that point. Using the amplitude coefficient appropriately adjusted the filter coefficients of the control filter and it is shown that the reproducibility of sound is improved.

In recent years, the number of sound-absorbing materials used in automobiles and other devices has been increasing, in which several materials are laminated instead of one material in order to reduce weight and improve sound absorption performance. In this study, cellulose nanofibers (CNF) were laminated on felt, which is generally used in automobiles, to improve the sound absorption performance. Three types of felts of different thicknesses and densities were laminated with CNF to measure the flow resistance and sound absorption performance. The results of the analysis of the amount of CNF and the changes in flow resistance and sound absorption coefficient are reported.

Radiation mode-based loudspeaker array is applied to a head-rest audio system for realizing personal audio. The objective is to deliver sound to a nearby listener while reducing sound leakage to surroundings. Radiation modes are amplitude and polarity combinations of loudspeakers, which are orthogonal to active and reactive acoustic powers. The amplitude and polarity with the maximum reactive-to-active ratio is employed for confining sounds in the near field. A linear array with three loudspeakers is developed and located near an ear of HATS. The sound radiation characteristics in anechoic room are presented. Distance between the array center and listening point is defined 3cm. Sound leakage is measured at 30cm of radial distance from the array center. Speech frequency band from 300 and 3400 Hz is analyzed.

Sound masking is a technique used to make conversations less audible to others. This technique can be used to protect speech privacy in open spaces such as hospitals or shared offices. On the other hand, a conventional sound masking technique can be noisy after masking because it adds masking sound to the target sound. In this study, we investigate sound masking using active noise control, which is effective for noise reduction. We focused on the phonological and prosodic characteristics of speech and proposed a low-noise sound masking method by using active noise control to change both features. In the previous study, the masking effect was good for monosyllables, but the masking effect decreased when continuous sounds were controlled. In contrast, the proposed method considered prosodic properties, which was not taken into account in the previous study, in addition to phonological properties, and as a result, better masking effect was obtained even for continuous sounds. Furthermore, it was confirmed that the proposed method can reduce the sound volume after masking.

A monitoring support using a melody designed based on the cognitive function of elderly people is being considered for the purpose of helping people who need care to become independent. Melodies designed by designers based on the image of daily activities are being considered for this monitoring support as a recall support sound. In fact, previous studies have been conducted on the evaluation of functional sounds for daily life considering the body clock and the construction of a functional sound model considering the impression evaluation of elderly people and sound parameters. However, it is expected that it takes time and effort for elderly individuals to associate melodies with their daily activities. In this study, we focus on memory impairment, in which the elderly people forget daily activities (such as eating and bathing) due to cognitive decline, and investigate functional sound cues for daily life based on the estimation of brain regions involved in memory recall by analyzing cerebral blood flow using fNIRS.

Conventionally, discomfort caused by the loudness of broadband sound has been a problem in the operating noise of rotating machinery whose power source is an internal combustion engine. Recently, with the shift to electric power sources, discomfort caused by the sound quality of pure tones has become a problem. The operating sound of rotating machinery is composed of a broadband sound and pure tones, and as the broadband sound becomes quieter, the pure tones become more prominent. Tonality is a psychoacoustic metric that expresses the prominence of pure sound, but the influence of other metrics on subjective evaluation of actual noise has not been clarified.

In this study, we examine the influence of psychoacoustic metrics on the perception of pure tones by combining subjective evaluation and psychoacoustic metrics related to pure tones, in order to understand the correlation between the evaluation of the degree of recognition of pure tones and psychoacoustic metrics.

The difficulty in recognizing what others say gets more when they speak rapidly and/or with poor articulation skipping some of the consonants. Because such damaged speech requires additional cognitive load for recognizing words. Elderly people with hearing loss have more difficulty even for clear speech because they lack the capability of hearing the high-frequency component of speech signal. We conducted a preliminary experiment to see the efficacy of modifying acoustic features such as amplitude and temporal resolution together with boosting high-frequency component of consonant parts. The result demonstrated that emphasizing the acoustic features of the consonant parts of input speech significantly improved their audibility. Therefore, we have developed an online hearing-aid system using a high-speed computer that detects consonant parts from the input speech and emphasizes them based on the result of the preliminary experiment. Consonants are categorized depending on the acoustic characteristics, and the category determines the method of speech emphasis.

In recent years, there has been a growing need for sound branding that takes advantage of the characteristics of sound. However, sound design is often based on subjective perceptions, and there are few examples of sound design based on the physical characteristics of sound. Additionally, it is difficult to find commonalities between different types of products only by extracting sound features based on frequency characteristics. In this study, a machine learning model for acoustic multi-parameters, based on CNN, was constructed to classify sound data by inputting the results of time frequency analysis, the correlation between carrier frequency and amplitude modulation frequency (Fast-SC), and a psychoacoustic evaluation scale. Then, feature extraction of the parameter with higher contribution to classification is performed for each data using SHAP. The results showed that loudness was higher when the sound pressure was higher, roughness, fluctuation strength and Fast-SC were higher when there was amplitude modulation, and prominence ratio was higher when there were multiple pure tones. This result confirms the effectiveness of feature extraction using a machine learning model for acoustic multi-parameters.

Recently, Physics-informed Neural Networks (PINNs) were proposed as useful numerical simulation methods for inverse analysis such as property identification. PINNs are methods to obtain physically satisfactory solutions by introducing a loss function with respect to the governing equations into a neural network. In this study, PINNs based on the wave equation was constructed for application to noise control systems. In this paper, we report a method to identify the acoustic attenuation parameters in an acoustic tube by recording the resonance state in the tube with a microphone. The obtained results are evaluated by comparison with the finite difference method.

With the goal of identifying the characteristics of body sway fluctuations when walking comfortably, we have built an AI system that classifies wavelet-transformed diagrams of the envelope of body sway when walking comfortably and when walking monotonously, using 119 pieces of data collected by FY2022. In this presentation, we report the results of having the AI system classify 22 pieces of data collected in FY2023, which were not used to build the AI system, resulting in a 73% correct response rate, and the results of visualizing the deep learning used in the AI system to confirm what parts of the diagrams the AI system is focusing on for classification.

In a hospital, there are various noises such as the operation by medical equipment and human voices, resulting in a bad sound environment with loud background noise. Alarms are sounded frequently in the presence of loud background noise, which may cause healthcare workers to fail to notice the alarm sounds and lead to medical accidents. On the other hand, if the sound pressure of alarm sounds is louder as a countermeasure, patients may feel the alarm sound uncomfortable. From this situation, it is assumed that the difference in sound quality between the background sound and the alarm sound should be appropriate. In this study, we examine from an acoustics perspective how changing the difference in sound quality between the background noise and the alarm sound affects degree of cognition and comfort of the alarm sound. Based on the results of sound quality evaluation and the analysis of the acoustic characteristics of background noise and alarm sounds, the effects of the difference in the type of alarm sound and background noise on the degree of cognition and comfort of listening to alarm sounds were ascertained.

Fiber-based porous sound-absorbing materials, such as glass wool, are used in a wide range of applications due to their manufacturability and performance. However, fragile surfaces may require a protective layer. Sound absorption can be reduced or improved depending on the protective layer. In this study, non-woven fabrics and PE membranes are added to the glass wool surface to protect the surface and to improve the sound absorption coefficient. Theoretical analysis using the transfer matrix method was conducted to estimate the sound absorption characteristics. The normal incident sound absorption coefficient of the fabricated samples was also measured.

Semi-closed work booths have the advantage of being low-cost and easy to install. However, they are not as effective as closed work booths in terms of sound insulation performance due to their open areas. Consequently, there is a concern regarding the potential for speech information leakage in the context of web conferencing and telecommuting. In the case of a semi-closed work booth with sound insulation measures, it is challenging to improve the sound insulation performance in the low-frequency range due to the presence of an open areas, while some improvement in sound insulation performance can be expected in the high-frequency range. Therefore, this study focused on listening to consonants that have a lot of energy in the high-frequency range. We present a method for preventing speech information leakage by controlling sound pressure in the high-frequency range using word intelligibility tests.

As potential calibration methods for the low-cost microphone such as MEMS type, two alternative methods, the pressure calibration method by a modified active coupler and the bulk calibration method using a reverberation chamber are proposed and the feasibility is investigated. The modified active coupler is designed to make that the comparison calibration with the reference microphone is possible for the surface mounted configuration. For the bulk calibration method, the procedure of sound power measurement with the calibrated reference sound source is applied. The proposed methods have relatively higher uncertainty compared to the standard microphone calibration method standardized in IEC, however it still maintained within the acceptable level regarding the practical application of MEMS microphones.

Wind power is attracting attention as a major renewable energy source, but the noise generated by wind turbines may affect wild birds. To obtain basic information on the relationship between wind turbine noise and birds, we evaluated the hearing sensitivity of a coastal bird, the black-tailed gull Larus crassirostris, to noise. Four wild gulls were trapped and their electrocardiograms were measured in the laboratory while they were exposed to 60 dB of wind turbine noise from a loudspeaker. Significant increases in heart rate were recorded in response to noise in one of the four individuals. This result suggests that at least some black-tailed gulls can detect wind turbine noise.

Tones emitted by metal materials change by the physical properties of metals, structure, and microstructure. However, there are very few studies on the influence of differences in the frequency of hitting the sound of the material and the tones on people. In this study, we consider the different tones of materials by the physical properties of metals, structure, and microstructure. Furthermore, we aim to evaluate the quality of the tone of the material by acoustic factors. In this paper, we quantitatively clarified the effects of differences in zinc content in brass on hitting sound using acoustic factors. In this experiment, we analyzed the hitting sound of brass with different zinc contents. Moreover, we considered the difference of hitting sound by hardness. From the result, we proved that as the hardness of brass increases, the decay time increases. In the future, we plan to investigate the relationship between the zinc content of brass and the hitting sound from a materialistic perspective, such as tensile testing of the material.

The rainfall noise hitting umbrellas obstructs ambient sound, making it difficult for the visually impaired to go outside during rainfall. To solve this problem, umbrellas with low rainfall noise have been developed, but no quantitative evaluation method for rainfall noise of umbrellas has been established. Last year, we fabricated a tank for rainfall with reference to ISO 10140-5:2021 and reported the results of rainfall sound evaluation of umbrellas in artificial rainfall, but we could not reproduce the acoustic characteristics of natural rainfall. In addition, acoustic laboratories are vulnerable to water, and the amount of water used during measurements should be as small as possible. Therefore, this paper proposes a new evaluation method using drips at a single point. This method analyzes the sound of drips at several points selected in consideration of the shape of the umbrella, and then sums up the results in terms of energy. The effectiveness of this method was examined by measuring the rainfall sound of umbrellas using the drip evaluation method and comparing the results with those of natural rainfall and using a rainfall tank. The results of the study showed that quantitative evaluation is possible with artificial rainfall using a minimum amount of water as a relative comparison for each measurement target. In the future, we plan to investigate whether the spectral balance of natural rainfall can be reproduced by improving the drip position.

Amid the shortage of human resources in the logistics industry and the increasing demand for logistics in urban areas, mountainous areas, remote islands, etc., a licensing system for drones flying beyond visual line of sight has begun, and the day when drone logistics will be put into practical use is drawing near. On the other hand, when logistics using drones begins in earnest, social issues such as safety and noise are expected to increase. So far, the authors have measured the sound generated by drones of several sizes during flight and reported on the characteristics of the sound generated¹⁾. By obtaining the 3dB/Double weight characteristic from the measurements, we estimated the single-event sound exposure level when a drone of any weight flies at any flight altitude and horizontal position at any speed.

Bio-coke (hereinafter abbreviated as BIC), which has carbon-neutral properties, has been attracting attention, and it has been clarified that unused rice husks can be converted into BIC and used as a substitute for carburizing materials. In addition, since rice husks contain a large amount of silicon, it is also attracting attention as a silica material, and can be expected as an alternative to Fe-Si alloys. In this study, we investigated the change in the amount of silicon depending on the contact time with molten metal in order to clarify the effect of silica from rice husk BIC. The base metal alloy was melted and cut into 500g pieces and remelted in a double ceramic crucible in an induction melting furnace. When the molten metal temperature reached 1773K, the end faces of the rice husk BIC of φ46mm were added so that they were in contact. As a result, in addition to the carburization action, the silica addition action effectively appeared in the casting process. This result suggested the possibility of green casting.

During the reaction processes of pyrolysis and gasification, biomass releases small molecular compounds and simultaneously produces thermally stable char. Understanding the characteristics of compounds with a wide range of molecular weights is important to achieve a high degree of control over the products of pyrolysis and gasification. However, compared to tar and gas among pyrolysis products, char is difficult to analyze experimentally, and its molecular structure and formation mechanism have not been clarified in many aspects. In this study, the mechanism of char formation in the initial pyrolysis of lignin was investigated using ReaxFF-MD simulations, which can analyze the pyrolysis behavior of organic materials at the molecular level. Isothermal simulations of the initial pyrolysis of lignin were performed for 500 ps at 11 temperatures between 873 and 2873 K. The simulation results showed that the initial pyrolysis of lignin was not affected by the thermal decomposition of lignin. Analysis of the molecular structure of char in this computational model suggests that it develops a polycyclic structure through ring-opening and ring contraction.

The introduction of solid biofuels to replace coal is expected in order to build a sustainable society. In this study, we focused on dry torrefaction (DT) and densified molding as methods for reforming solid biofuels. The purpose of this study is to investigate the effect of DT and densified molding conditions on the char yield and the absolute amount of char of solid biofuels. In the study, four types of solid biofuels are used, fuel-R (raw powder), fuel-DT (DT powder), fuel-RB (densified fuel from raw powder) and fuel- DTB (densified fuel from DT powder). To evaluate the absolute amount of char, EFC (enhancement factor of char) is defined as the ratio of the char mass of each fuel to the char mass of fuel-R. The results obtained are as follows. At the molding temperature of 100°C, the apparent density of fuel-DTB is lower than that of fuel-RB and decreases with DT temperature. The apparent density of fuel-RB and fuel-DTB increases with molding temperature. The effect of DT on EFC is not large, while the effect of densified molding on EFC is large. From the investigation on the relationship between EFC and apparent density of fuel-DTB, it is found that EFC is closely related to the apparent density, which means that the increase in EFC results from the suppression of volatile matter evaporation and the conversion of some of the volatile matter to fixed carbon.

To build a sustainable society, the utilization of solid biofuels is expected to replace coal and coal coke. In this study, we focused on wet torrefaction (WT) treatment and densification forming to produce solid biofuels with fuel properties comparable to coal. WT is advantageous for reforming high moisture biomass feedstock, and Japanese cedar powder with 83% and 95% moisture content is used as the WT experimental sample. The aim of the study is to clarify the effects of WT conditions (WT temperature, holding time, water/biomass mass ratio) and densification on the char yield of four types of solid biofuels, Fuel-R (raw powder), Fuel-WT (wet torrefied powder), Fuel-RB (raw densified biocoke) and Fuel-WTB (wet torrefied densified biocoke). The obtained results are as follows. Char yield is enhanced by densification forming due to suppression of volatile matter evaporation. Char yield of WTB at B/W=1/5 is higher than that at B/W=1/20. The optimal WT conditions for producing fuel with high char yield is found to be B/W=1/5, WT temperature 240°C and WT residence time 120min. The Enhancement factor of char for RB and WTB is correlated with particle density.

The purpose of this research is direct heat utilization of herbaceous biomass, which has a large amount of resources but a large amount of ash, and effective utilization of combustion ash. To date, the following findings have been obtained.

(1)A high-density solid fuel was continuously produced from adzuki bean harvest residue and rice bran as raw materials.

(2)As a result of co-firing experiments with wood pellets in a commercial pellet stove, no cohesive clinker formation, which hinders effective use of combustion ash, was observed.

Laboratory corrosion tests were performed for investigating influence of heavy metallic salt on corrosion behavior of SUS310S and Hastelloy C22. The synthetic ashes with/without heavy metallic salt were used in the corrosion tests. The molten salt corrosion tests were performed at 510℃. It was found that the corrosion loss rate in NaCl-KCl-Na₂SO₄K₂SO₄-CaSO₄ simulated combustion ash with heavy metallic salt is higher than that in NaCl-KCl-Na₂SO₄-K₂SO₄-CaSO₄ simulated combustion ash. Based on the thermodynamic calculations, the simulated ash containing heavy metallic salts produced gas components, including sulfur oxidant and chloride, that enhanced the corrosion reaction compared to the corrosion reaction without heavy metallic salts.

We are developing a new combustion simulation technique that couples Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM) to accurately understand the unsteady combustion phenomena inside a stoker-type waste incinerator. The new simulation reproduces the detailed combustion phenomena throughout the furnace by mutually coupling the analysis results of the unsteady waste transport behavior and solid-gas reactions by DEM with the gas-phase combustion analysis results by CFD. In this report, we derived the particle parameters of the waste in the DEM from the angle of repose data obtained from the experiment and verified that these parameters can be used to reproduce the waste transport behavior in the DEM simulation. Additionally, we verified that the solid-gas reaction behavior of the waste can be analyzed by DEM-CFD coupling simulation. Furthermore, we conducted DEM-CFD coupling simulation of the overall incinerator, the transport behavior of the waste and the solid-gas reactions were analyzed simultaneously. In the future, we plan to conduct a DEM-CFD coupling simulation of the overall incinerator, including the interaction with gas-phase combustion reactions and solid-phase behavior.

To advance the evaluation of Carbon dioxide Capture, Utilization and Storage decarbonisation effectiveness in waste incineration facilities suitable for Japan, this study investigated the case studies of the cooperation between waste incineration facilities and CCUS in Japan to understand the current status of implementation and to evaluate the decarbonisation effectiveness of waste incineration facilities and CCUS projects. The results show that achieving the carbon neutrality goal for introducing CCUS in 300 t/D MSW incineration facilities is difficult. There are differences in emission reduction benefits depending on the type of CCU technology, with CCU-methanol being the most effective technology for CO2 emission reduction for achieving carbon neutrality in the 2050 forecast．

To build a sustainable society, the solid biofuels have come to attract attention as promising alternative fuels to coal in industrial furnace and boilers. We focused on wet torrefaction (WT) treatment to produce solid biofuels with fuel properties comparable to coal. The WT is a thermal treatment in hydrothermal media or hot compressed water in a temperature range of 180-260 ℃. To utilize WTB for industrial use, WTB with predetermined energy properties such as higher heating value (HHV) and solid mass yield (YM) has to be produced to meet the requirement in industrial furnaces and boilers. In this study, as the first effort to investigate a generalized estimation of YM and HHV of wet torrefied biomass, WT experiments are conducted by using Japanese cedar. The aim of the study is to clarify the effects of WT conditions (WT temperature, residence time, biomass/water mass ratio) on the energy characteristics (YM and HHV) of the wet torrefied Japanese cedar fuels (WT-Cedar) and the proportion of three major polymers (cellulose, hemicellulose, lignin) contained in the WT-Cedar. Experimental correlations of YM of three major polymers are presented with WT conditions. It is found that the YM and HHV of WT-Cedar can be estimated within an accuracy of about 10%.

The utilization of renewable and unused energy is supported by the FIT system and subsidies. On the other hand, the actual conditions and evaluation indicators are not well developed in complex energy systems, which is a challenge for further dissemination. In this study, we compiled a database of case studies from across Japan and constructed the R1ex indicator to evaluate the energy utilization level of energy systems, inspired by the R1 indicator used in the EU to evaluate waste incineration facilities. The usefulness of the R1ex indicator was confirmed by evaluating renewable energy utilization cases as case studies.

This paper examined the energy utilization efficiency of integration between municipal solid waste and wastewater treatment facilities. The R1ex factor was imported to define the energy utilization efficiency of the infrastructure. The result showed that the R1ex factor of the municipal solid waste management system was 0.35. In addition, this report also assumed and calculated the factors of the daily waste disposal quantities of 50 tons and 300 tons, respectively. By comparing the results, larger-scale facilities generally exhibit significantly higher energy utilization efficiency.

Waste treatment, which is essential for maintaining sustainability, is the responsibility of local governments in Japan, and in most cases, it is inefficient as it is only responsible for disposing of waste. Therefore, as the ideal waste treatment facility for decarbonization in 2050, I recommend the construction of large waste to energy facilities concentrated in industrial complexes. This can significantly improve overall efficiency and create a sustainable circular economy. Furthermore, by having the national government take the lead in operating the project, it was possible to break various current constraints.

Due to the development of automation technology in the Department of Waste Management and Recycling, robots are now being deployed in recycling factories and replaced a part of workforce. However, to implement the robots, factories need to spend a large amount of cost on creating a robot included line. This study creates an automatic sorting robot for beverage containers, designed for implementation within limited spaces and specify the challenges of robot development with real-scale sorting experiments. As a result, our robot successfully separates beverage containers into eight specific categories: PET (clear), PET (data shortage), PET (rest), PET (coffee), clear glass, brown glass, green glass, and cans from mix. The challenges to improving the robot’s ability are declared as improving the AI’s accuracy and robot’s control system, and developing conveyer belt to stabilise the container’s position.