As carbon neutrality and the circular economy are promoted, the thermal treatment of waste tends to be viewed as a controversial technology. However, waste thermal treatment can fulfil various roles in line with the objectives of these societies. Regardless of the era, reducing waste volume and ensuring its sanitary treatment are indispensable goals, and these goals will continue to be pursued in the future. Furthermore, in a carbon-neutral society, transitioning from fossil fuels to renewable energy is necessary. If waste plastic policies continue, by 2050 energy from waste thermal treatment will almost entirely be derived from biomass waste, potentially providing renewable biomass energy. Additionally, further optimization of energy utilization and CO₂ capture in large facilities will be required to contribute to net zero and even negative emissions. Various forms of carbon recycling are possible through thermal treatment. In a circular economy, thermal processing will play a role in the pretreatment of waste for metal recovery and must evolve to contribute to the circular economy. However, none of this can be achieved through technological development alone; the establishment of social systems is also essential. In near future, it will be necessary to establish a system in which only those that can achieve a certain level of energy and resource recovery will be recognized.

In a hospital, there are various noises such as operation sounds by medical equipment and human voices, resulting in an unpleasant sound environment with loud background noise. Alarms are emitted by equipment 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. Therefore, we propose an alarm sound identification system using deep learning to reduce the number of medical accidents caused by medical personnel missing alarm sounds. If we can develop a sound volume-independent identification system, it will lead to realization of a sound environment that is good for both healthcare workers and patients. In this study, we investigate a method to improve the accuracy of the system based on the acoustic characteristics of alarm sounds. Specifically, sound data that were enhanced with alarm sound characteristics using any one of or both a noise reduction method called instantaneous Phase Corrected Total Variation (iPCTV) and the cepstrum analysis is input to CNN. As a result, the case where both iPCTV and cepstrum analysis were used had the highest alarm sound identification accuracy among the methods used in this study. Especially, it was more effective when the alarm sound was at a low sound pressure.

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.

Office supplies, such as ballpoint pens, can be perceived as noise even at low volumes. Consequently, it is necessary to consider background noise levels in the intended usage environment when designing the sound quality of such products. However, traditional sound quality evaluations have often overlooked the effect of background noise. This study investigates the influence of background noise on the perceived sound quality of ballpoint pens. The results suggest that while perceived loudness is more susceptible to the effects of background noise, the impact on perceived sharpness may be more limited.

Regarding aerodynamic self-excited sound accompanied by resonance generated from a semi-cylindrical cavity, the frequency response of the vortex shedding section was investigated. A virtual 9 sound sources were placed on the downstream edge of the cavity, and the frequency response at the upstream edge of the cavity, its upstream bend surface part, and the center point of the cavity bottom, etc. were numerically analyzed. The relationship between the frequency response and the spectrum of the self-excited tone measured was considered. The dominant frequency of the self-excited resonance sound hardly coincides with any other frequency than the first resonance frequency of the frequency response analysis. It is presumed that the waveform of the self-excited sound generated by the periodic vorticity change near the downstream edge of the cavity contains almost no frequency components close to the high-order natural acoustic frequency and is affected by fluid dynamic interference.

The noise attenuation by a noise cover under the viaduct was estimated from the field test. The field test for the estimation was carried out at two sections, which are with and without the noise cover. Noise under the viaduct and close to the backside of a viaduct were measured for estimation. Vibration of slabs and a girder of viaduct were also measured. The estimation results of noise insulation indicated that bridge noise just under the viaduct were reduced by around 10 dB, with the maximum reduction of 15 dB in the frequency range of 250-315 Hz band. Bridge noise at the point 25 m away from the closest track was also reduced by around 10 dB in the frequency range of 160-400 Hz band and by around 5 dB in other frequency bands. However, it should be noted that the amount of noise reduction to total noise at the point 25 m away from the closest track depends on locations due to other noise sources.

In a few railway sections where no noise reduction is obtained by a noise barrier on the upper part of a viaduct, a noise cover concealing a lower part of a viaduct is used to reduce bridge noise generated while a train passes by. Countermeasures for the noise propagation related to civil engineering structures are rarely proposed except for a noise cover which completely covers the bottom of the viaduct. In this study, scale-model tests to replace the noise cover are conducted as fundamental research. Other than the noise cover, a girder side-hanging noise barrier, an inverted triangle noise barrier installed at a lower part of a viaduct as such, are tested. From the results, the inverted triangle noise barrier showed almost the same noise reduction. Validation tests showed that proposed methods have potential for replacing a noise cover.

At recently, the research of sound metamaterial which has typical sound characteristics are done actively. In this paper, we show the resonance attenuation effect inside the small space using developed sound metamaterial. The point of developed sound metamaterial is wide frequency range of highly sound absorption characteristic. By the evaluation, we verify that four corner arrangement with λ/6 space attenuate resonance inside small space optimally.

Physics-informed Neural Networks (PINNs) are numerical methods that achieve physically consistent simulations by incorporating loss functions derived from governing equations into neural networks. In this study, we propose a method for estimating the acoustic radiation impedance of tubes by constructing PINNs based on the wave equation and analyzing resonance states recorded by microphones placed within acoustic tubes. The validity of the obtained results is evaluated through numerical simulations.

A diagnostic tool using vibration and acoustic emission (AE) measurements has been developed to detect damage and evaluate the remaining life of rotating machinery. For example, some machines in a process plant can be screened by the tool for those requiring attention, such as unbalanced rotation and bearing defects. The AE measurement technique, as a non-destructive inspection method, was applied to the main rotating bearing of a wind power plant to investigate and detect damage on the outer ring surface. In addition, the progression of similar damage on another wind turbine was monitored remotely. To achieve more efficient and effective operation and maintenance, digital transformation through advanced tools that enhance conventional methods is indispensable. This paper introduces our advanced technologies and application cases related to wind power plants that contribute to the decision-making of asset owners as part of strategic maintenance aimed at ensuring safe and stable plant operation.

When Shinkansen trains run at high speeds in excess of 300 km/h, the aerodynamic noise generated by the bogies makes a significant contribution to the total noise observed at a distance of 25 m from the nearest truck. In this study, wind tunnel tests were carried out on a 1:5 scale model of the actual vehicle to experimentally investigate the mechanism of aerodynamic noise generation by the bogie of a railway vehicle. A number of microphones were flush mounted on the surface of the inner wall of the space containing the bogie (bogie cavity) to investigate the correlation between surface pressure fluctuations and the far field sound, and to analyse the direction of sound wave propagation by determining the phase difference between microphones. The results obtained showed that low frequency aerodynamic noise, which is highly correlated with the far field sound, is generated downstream of the bogie cavity and that the sound waves propagate upstream of the bogie cavity section.

The growing demand for more efficient waste sorting processes has highlighted the need for advancements in technology within the waste treatment industry. This paper aims to investigate and evaluate the effectiveness of underlying technologies that support the transportation and sorting of commercial waste. Our examinations indicate that the performance of an automated robotic vehicle is approximately one-fifth of that of human operators, while an AI (Artificial Intelligence)-powered sorting robot achieves about one-third of human performance. Additionally, we developed a robot-human coexistence model to better understand how these systems can complement each other. The model was based on an evaluation method we created, referred to as “resource shift.” By optimizing the collaboration between humans and machines, the model lays the foundation for their potential future application in real-world facilities. This work offers valuable insights into enhancing waste sorting efficiency through the integration of automation and human labor, opening the door for more advanced waste management solutions.

This study aims to understand the current status of waste plastic sorting and to examine the limitations of existing identification technologies. A comprehensive database (DB) was constructed by integrating reflectance spectra, shape characteristics, and contamination status of samples collected from treatment and discharge sites. Through analysis using machine learning, it was confirmed that spectral changes indicative of PVC can be detected. However, a decline in classification accuracy was observed due to deformation and color variations inherent in waste plastics. At present, most identification models do not account for such contamination and deformation. Therefore, to ensure the reliability of classification results, the inclusion of reference data provided by manufacturers is considered essential.

Because of the rapid increase in global energy demand in recent years, it will be difficult to continue to consume fossil fuels of the same quality and quantity as at present. Therefore, the use of non-fossil energy sources such as renewable energy is being promoted. In this study, we examined the use of CO₂ as a biomass gasifier, assuming exhaust gas recirculation. We focused on the dependence of CO₂ gasification behavior of woody biomass on CO₂ concentration and searched for conditions that would increase the heating value of the syn gas. Gasification experiment is done using a small packed bed gasifier and crushed black pine pellets as a sample. The results showed that the syn gas and heating value of the produced gas increased with increasing CO₂ concentration, suggesting that the use of CO₂ as a gasifier helps to improve the gasification efficiency.

In the field of refuse collection, the need for contactless waste collection is increasing due to infectious diseases and labor shortage. In this study, we developed an autonomous robot that can collect and automatically transport waste containers. In this paper, we examine the traffic rules and travel area according to the road environment on which the robot runs and conduct a travel test using a fleet control system that controls multiple robots in a simulated environment. The results suggest that the success rate of autonomous driving of robots increases when the driving area and route are set according to the road environment and “waiting points” are set at locations where robots pass each other, and that robots can execute tasks without interfering with each other by sharing their location information and planning their routes. The results also suggest that robots can execute tasks without interfering with each other by sharing their location information and planning their paths.

VSPS, an original pressure wave type dust removal equipment, has been developed. In the demonstration test, it was confirmed that the use of polyimide film instead of SUS film can reduce the number of protectors for boiler water pipe protection without reducing dust removal performance. Since the polyimide film is lighter and more flexible than the SUS film, the workability and safety of the film roll replacement are improved. In addition, since the protection protector can be reduced, the operation cost can be greatly reduced. The demonstration operation is continued, and stable operation is confirmed through long-term operation, and the challenge for cost reduction and performance improvement is also carried out, and the improvement of practical application equipment is advanced.

The heat transfer tubes of waste-to-energy boilers undergo wall thinning over time due to high-temperature corrosion. The tendency of wall thinning is influenced by the corrosive environment, which varies depending on the waste properties, design conditions, and operating conditions. To improve the accuracy of wall thinning predictions, it is necessary to establish a method that can appropriately account for changes in the corrosive environment, even when they deviate from initial design assumptions. In this study, we developed a prediction method that combines a wall thinning prediction based on statistical modeling with physical modeling of the wall thinning mechanism caused by high-temperature corrosion.

It is known that removal of dusts on the boiler surface is one of the means for high-efficiency power generation in municipal solid waste incineration plants. We introduce an operation performance of new boiler cleaning system to remove of dusts. This system has two instruments to clean boiler tubes. Firstly, it was the spray cleaning system to use water and clean radiation chambers. Secondly, it was the shock pulse sootblower to use fuel gas and oxygen gas and generate a shock pulse, then it cleaned boiler superheater. This system contributed to prevent fly ash from piling up, the thickness of fly ash on superheater changed from 10 mm to 3 mm. It also contributed to recover the efficiency of heat absorption because of the exhausted gas temperature drop by 50 degrees at the inlet superheater. Besides, the continuous operation period became longer from 100～150 days to 200 days after the install. This result showed the superior operation performance of new boiler cleaning system. We proceed to the install this system to boilers in the incineration plants.

Visual and sound inspections are used to diagnose the integrity of the refractory of Waste incineration plant. Percussion inspection is a widely used method, but it is dependent on the ability of the inspector and requires the use of temporary scaffolding and vehicles for work at height when the inspection area is at high elevations or over a wide area. Therefore, in cooperation with Toin University of Yokohama, we report on the results of internal defect measurement using a non-contact acoustic exploration method, which is expected to solve these problems, on specimens and refractory materials.

Waste-to-energy plants generate electricity while ensuring sanitary waste disposal through incineration. Maintaining stable combustion requires precise control of waste feed, grate speed and grate air, typically managed by automatic control systems. Kanadevia has developed a comprehensive solution that combines AI models predicting combustion deterioration based on sensor values with an AI model, Task-Relevant Encoding of Domain Knowledge (TREK), that predicts combustion images. TREK uses dynamic mode decomposition to extract real-time periodic changes in combustion images, integrating Fast Fourier Transform to selectively focus on specific frequency bands. This approach enables us to isolate and analyze long-period changes associated with waste condition variations, which are critical for predictive control. The combination of these AI models significantly enhances overall combustion stability. To validate the efficiency of TREK, we conducted a test at an actual waste-to-energy plant. The results demonstrated that implementing the TREK reduced the combustion area on the post combustion grate by approximately 60% compared to controls without TREK. This significant reduction enabled more stable combustion in the primary combustion zone of the furnace, indicating improved overall combustion efficiency and control.

In WtE facilities, it is necessary to balance the suppression of CO₂ emissions with the reduction of stable operation costs. Additionally, due to concerns like the shortage of experienced operators, it is becoming important to support operations and management with systems that remove personal bias, along with traditional hands-on management. Considering this, our company has developed an integrated plant operation system with a scoring function to make operations easier and more stable. This report will focus on the equipment scoring function, which detects early signs of equipment failure, and its operational status.

With the adoption of the private finance initiative (PFI) method, the privatization of waste treatment facilities is in progress, which the private sector not only constructs the facilities but also operates them after construction, shift to long-term comprehensive management for facilities already in operation. On the other hand, with the contraction of the working-age population due to the aging of society, the industrial plant sector is facing a serious shortage of plant operators. The author has been developing automated operation systems for waste-to-energy plants and implemented the remarkable AI system called “BRA-ING” in 2020, focusing on automated operation for incinerators. Since then, additional functions such as steam generation volume control and chemical agent injection control for flue gas treatment have been added to expand the scope of automated operation. On this paper, author will report the updated automation systems and the result of the verification trial at the commercial facility, where we achieved the long-term fully automated operation which would leads to the contribution of labor saving of operators.

In a general waste incineration plant of the grate type, a funnel-shaped device called a feed hopper is provided. Waste is put into the feed hopper and fed into the incinerator. However, sometimes waste gets stuck inside the feed hopper and does not feed into the incinerator. If this condition persists for a long time, no waste will be fed into the incinerator, and the usual combustion cannot continue. We have developed an image analysis system to detect when waste gets stuck inside the feed hopper at an early stage. When waste gets stuck inside the feed hopper, the movement of the waste becomes smaller compared to the normal case. An abnormality is detected based on this observation. The movement of the waste inside the feed hopper is calculated using image correlation from two time-series images from the monitoring cameras. These cameras are used by operators to visually check the waste feed. To verify its accuracy, the system was applied to past similar cases, and it was confirmed that abnormalities could be identified at an early stage. Therefore, this system is being utilized for remote monitoring of waste incineration plants in Japan.

To achieve carbon neutrality, recycling organic waste is crucial. We aim to reduce CO₂ emissions and recover carbon resources through pyrolysis and gasification instead of incineration. We developed two chemical recycling technologies: the EUP pressurized two-stage gasification system, and the ICFG internally circulating fluidized bed gasification system for low-calorific-value feedstocks. Laboratory tests using ICFG on mixed plastics showed that higher temperatures increased gas yield while reducing oil yield, Besides, the results of simulated municipal waste showed that the Char fraction decreased and decomposed oil increased with a higher proportion of synthetic resins, rubber, and leather. Water soluble oil increased with a higher percentage of biomass.

Technology for converting CO₂ into solid carbon is being developed. Based on the results of a 1 kg-CO₂/d scale laboratory experiment, a 10 kg-CO₂/d scale continuous solid carbon production/separation system was developed and operated for a cumulative period of 45 hours. It was confirmed that it was possible to continuously produce solid carbon and separate solid carbon from catalyst tube while maintaining the solid carbonization reaction rate, and that it could withstand long-term operation.

To achieve CO₂ capture at a WTE plant, it is necessary to deal with fluctuations in the quantity and quality of flue gas during waste incineration, and to deal with substances specific to the waste, such as Cl, and the facility area, construction costs, and running costs must be kept within an economically acceptable range. We are working to resolve these issues through our Green Innovation Fund project, "Carbon Neutral-type WTE based on the chemical absorption method."

Securing human resources is an unavoidable issue in the waste treatment business，and we think that the impact of this issue will become apparent at an early stage in the operation of recycling facilities.

In this paper，we showed that introducing a sorting system using robotics and increasing the working hours of the robots leads to cost reduction.

As labor costs continue to rise in the future，it is expected that the cost benefits of applying robots will become greater.

We have been exploring improvement methods for carbon particle incineration performance using nonthermal plasma. The plasma was generated by surface dielectric barrier discharge. In this study, the effect of a sub-electrode and the voltage application techniques to it was investigated. Those techniques included the “floated type”, “same-voltage type”, and “LC type”. The incineration performances will be reported in detail in the presentation.

The transportation sector accounts for approximately 20% of CO2 emissions in Japan, and mobility is facing a turning point in terms of environmental considerations. In this study, we evaluated the performance and utilization of mobility vehicles powered by compressed air as one of the driving sources. Specifically, we developed and tested a compact three-wheeled mobility vehicle powered by air, electricity, and human power, and investigated effective ways to use the vehicle. As a result, it was shown that this vehicle is effective for use in facilities where there is a demand for low-temperature waste heat and compressed air.

A Stirling refrigerator has a structure in which a high-temperature compression section and a low-temperature expansion section are arranged via a regenerator, and uses a single-phase gas as the working fluid. The enclosed regenerator has the role of storing and exchanging heat as the working fluid flows through it, and its specifications determine the performance of the refrigerator. This report presents the results of an experimental evaluation of the performance of a regenerator made of thin stainless steel wire when the wire diameter and bulk density are changed.

Our research group has been developing a multiple-ion probe measurement system capable of measuring combustion conditions and flame propagation in a gasoline engine. This measurement system is compact and lightweight, allowing it to be mounted on machinery operating in the field to measure the engine during actual operation. In this study, the multiple-ion probe measurement system was installed on a brush cutter to measure the combustion conditions inside the engine while performing actual mowing operations. The obtained data successfully reconstructed the combustion state inside the engine. Furthermore, detailed analysis of the data confirmed that the operating conditions influenced the combustion state within the engine. This experiment demonstrated that the proposed measurement system is useful for engine combustion measurement under real operating conditions.

In recent years, Physics-informed Neural Networks (PINNs) have been proposed as an effective numerical simulation method for inverse problems such as parameter identification. By incorporating loss functions derived from governing equations into neural networks, PINNs enable simulations that inherently satisfy physical laws. In this paper, we report preliminary investigations on a three-dimensional thermal design method for heat sinks based on PINNs. A PINN model was constructed to output the temperature field using temporal and spatial coordinates as input features. The validity of the proposed method was assessed through comparisons with the finite element method (FEM).

This research was conducted with the support of JSPS KAKENHI Grant Number 22K12453, with the aim of utilizing herbaceous biomass, which has a large resource amount but also a large ash content, for direct heat utilization and effective utilization of combustion ash. The findings were obtained. (1) The conditions for continuous production of high-density solid fuel (Bio-coke) were investigated using adzuki bean harvest residues scheduled for disposal as the main raw material. It was found that continuous production with excellent production volume per unit time and energy efficiency was possible. (2) Experiments of co-firing wood pellets with a commercially available pellet stove showed a decrease in the average combustion temperature, suggesting once again that the formation of caking clinker, which prevents the effective use of combustion ash, is suppressed.

Renewable energy storage plays a crucial role in achieving carbon neutrality. This study focuses on compressed air as an energy storage technology and conducts a comparative analysis of its various utilization approaches in an industrial setting. Specifically, assuming a model factory, we evaluated the effectiveness of using compressed air for power generation, direct supply to air lines, and as a driving source for mobility. Through this comparison, the characteristics of each method in terms of efficiency and applicability were analyzed, leading to the proposal of optimal utilization strategies for compressed air energy storage.

Convective heat transfer is the factor that has the greatest effect on latent heat storage through melting, and it is believed that promoting heat transfer through forced convection will result in a significant reduction in the latent heat storage time. In this study, we attempt to enhance heat transfer by injecting high-temperature air onto the latent heat storage material to cause a phase change and generate forced convection within the molten liquid phase. This paper reports the results of an experimental study on the melting characteristics when a jet of high-temperature air is impinged on a paraffin-based latent heat storage material.

CO₂ hydrate is a solid in which water molecules form a cage-like structure that encapsulates CO₂ molecules, and it has attracted significant attention for CO₂ capture and energy storage applications. This study investigates the pH changes associated with CO₂ dissolution in water and proposes a method for estimating CO₂ concentration by analyzing the hue of a pH indicator. Initially, BPB aqueous solution, a pH indicator, was added to aqueous solutions with various pH values, and the resultant color changes were recorded using a visualization device. The RGB values extracted from the captured images were analyzed to establish a correlation between pH and hue. Subsequently, CO₂ concentration was determined from the pH values, and a relationship between hue and CO₂ concentration was obtained. These findings demonstrate that the proposed pH indicator–based method is effective for measuring the distribution of CO₂ concentration in water.

In recent years, increasing environmental awareness has led to the popularization of compact personal mobility vehicles, and among them, specific compact motorized bicycles have attracted much attention. In this study, we focused on improving the riding comfort of drivers as a contribution to the popularization of specific small-motorized bicycles, and implemented and evaluated a body lean control mechanism in a vehicle under development. Specifically, experiments were conducted to measure the effectiveness of the lean control mechanism in improving riding comfort, including quantitative evaluations that quantify the load on the driver based on acceleration data during driving, and the effectiveness of the control mechanism was confirmed.