In this study, the effects of bio diesel fuel (BDF) and mixing air into the fuel as fine bubbles (FB) on combustion and exhaust characteristics were investigated for a high-speed diesel engine. As a result, the NOx emission reduction effect was confirmed when air FB were mixed in BDF as well as in A-heavy oil. In particular, the maximum reduction was 15.2 % at 75% load and 50 mL/min air volume, and the load average reduction was 10.9 %. In terms of fuel consumption reduction effect, no significant reduction in fuel consumption was observed when FB were mixed.

With Russia's invasion of Ukraine, the price of fossil fuels such as natural gas has skyrocketed, and all countries are now required to be self-sufficient in energy. Despite Japan's large amount of organic waste and biomass, they have not been used effectively as energy by then. To solve these problems, we have been developing a High Functional-Direct Carbon Fuel Cell (HF-DCFC) composed of a molten salt gasification system and tubular molten carbonate fuel cell (T-MCFC), which can use organic waste as fuel since 2012. The HF-DCFC performance is affected by the fuel type because the fuel gasification field and the power generation field are in the same reaction field. Therefore, this paper examined the influence of the difference between soy sauce cake and wood pellets as fuel on cell performance. The carbon content of soy sauce cake and wood pellets was almost the same, but soy sauce cake had more salt and about twice as much moisture as wood pellets. As a result, although the cell voltage dropped by 50 to 100mV as soon as the soy sauce cake was fed, it was enhanced by about 50mV by feeding wood pellets. Although we could confirm the influence of the difference in fuel species on cell performance, we must examine what kind of ingredient is affected.

In this study, a high-density solid fuel (Biocoke) was used, which was produced using discarded azuki bean harvest residue as the main raw material. And rice bran was mixed in various proportions as the sub raw material. Here, adzuki bean harvest residue is a herbaceous biomass with high ash content. These Biocoke and wood pellets were mixed and burned in a household pellet stove, and the resulting combustion ash was compared. These results suggest that Biocoke made primarily from adzuki bean harvest residue has the effect of suppressing the formation of caking clinker (suppressing melting). It was also found that the mixing ratio of rice bran results in differences in the formation of caking clinker (has an effect of improving characteristics). The composition of combustion ash obtained from comparative combustion experiments was analyzed. And some substances were detected that raise concerns about the effective use of combustion ash.

Stable operation of coal gasifier is the key subject for practical use of Integrated coal Gasification Combined Cycle (IGCC). It is necessary to maintain the gasifier temperature above the slag fusion temperature in order to ensure stable slag discharge. This temperature has been determined by the standardized coal ash fusion temperature measurement, which requires a lot of work and time. Therefore, in order to improve the operability of IGCC, coal ash fusion temperatures were predicted using chemical composition of ash and machine learning technique in this study. As a result, it was confirmed that it would be difficult to predict ash fusion temperatures for Biomass by Coal data with small amount of biomass data.

In this study, a digital twin advanced control method integrating laser diagnostics and computational fluid dynamics (CFD) was developed for the digital transformation (DX) of industrial processes. Computed Tomography-Tunable diode laser absorption spectroscopy(CT-TDLAS) and Laser Induced Breakdown spectroscopy(LIBS) monitoring systems were developed to monitor the concentration and temperature of industrial processes. CT-TDLAS is based on the CT method using absorption spectra of molecules such as H2O, CO2, CO, O2, NH3, and hydrocarbons and allows real-time measurement of temperature and concentration distributions in two and three dimensions. LIBS is an analytical detection technique based on atomic emission spectroscopy for determining elemental composition. The integration of laser diagnostics and CFD enables the prediction of nonlinear phenomena such as combustion, and the feasibility of digital twin advanced control has been developed and demonstrated using a CH4-NH3 swirl burner.

During pipe installation, preheating using a burner is conducted to prevent the formation of hardened structures, but its efficiency is low at just a few percent, and uniform heating requires heating from multiple directions. On the other hand, induction heating (IH) improves efficiency to 50-90%, but selecting the appropriate coil for the heating target is challenging, and errors in selection can result in either no magnetic field penetration or localized heating. Therefore, we aim to establish a simplified matching method for IH coils and controls through digital transformation (DX) by acquiring matching data for preheating IH coils and test pipes before welding.

In recent years, the introduction of renewable energy has been increasing to reduce carbon dioxide emissions, and the development of energy storage technology to maintain the balance between supply and demand of electricity has been actively carried out. The authors have proposed an electricity storage system in which Compressed Air Energy Storage (CAES) is constructed using pneumatic equipment installed in many factories. Reciprocating expanders for small CAES are suitable, and further improvement of the efficiency of the expander is necessary for CAES to be widely used. In this paper, the author proposes a method to switch the timing of the transition from isobaric to adiabatic expansion in the expansion process of a reciprocating expander according to the operating conditions. It reports on the effectiveness of the proposed method, which was confirmed by comparison with the results of an actual experiment and a conventional compact expander.

Compressed biomethane gas (CBG), a biofuel, is attracting attention in India and other Asian countries as a means of decarbonizing internal combustion engines. In this study, we experimentally clarified the effect of methane gas mixed with CO2 on the performance of a spark-ignition engine fueled with simulate CBG. The results showed that the maximum in-cylinder temperature decreased as the mixture ratio of CO2 increased, suggesting that the cooling loss was reduced due to low-temperature combustion. It was found that although CO2 blending decreased the flame propagation speed, the suppression of cooling loss was dominant, and the thermal efficiency was improved with lower exhaust gas emissions.

In recent years, the development of fuels that reduce CO2 emissions in the process from production to use has been promoted with the aim of achieving carbon neutrality. Hydrogen fuels in particular are attracting attention as a fuel that can reduce CO2 emissions to zero by utilizing renewable energy sources. However, while demand for hydrogen fuels is currently rising rapidly, the supply of hydrogen fuels has not been able to increase stably, and it is not yet clear whether the entire consumption can be covered by production from renewable energy sources alone. Therefore, it is hoped that mixing hydrogen with other fuels will reduce the initial requirement and lead to a stable supply in stages. Natural gas, which has an excellent stable supply, is a suitable fuel for mixing, but the combustion characteristics of hydrogen and natural gas in co-firing have not yet been sufficiently studied. This study focuses on the composition of the fuels and aims to clarify the combustion characteristics, especially the areas where thermal efficiency can be improved, for three factors: hydrogen mixing ratio, excess air ratio and power output. Experiments were carried out on a mixture of methane and hydrogen, the main components of natural gas, using a rapid compression and expansion machine. Analyses were carried out using pressure diagrams and heat generation rates taken under various conditions, and visualized images of the combustion process taken using a high-speed video camera.

To meet the emission regulations that are becoming stricter year by year, it is important to reduce emissions from spark-ignition engines, which are expected to continue to account for a certain share of the market in the future. The main emission control method for spark-ignition engines is the use of three-way catalysts for CO, NOx, and HC purification, but there are issues such as inactivity at low temperatures and the high cost of supported precious metals. In this study, a reaction model focusing on CO-NO redox reaction was developed for Rh catalysts to facilitate prediction of catalytic performance. Temperature rise tests were conducted to confirm the CO and NO purification rate behavior, and temperature-steady-state tests were conducted for several gas compositions in the low purification rate temperature range. From the test results, equilibrium constants for the adsorption and desorption reactions of CO and NO on the Rh surface at each steady-state temperature were calculated based on the differences in purification rates caused by the differences in gas composition. Based on the obtained equilibrium constants and the test results, an Arrhenius plot was generated to calculate the reaction rate constants for the CO-NO reaction on the Rh surface. Parameters were adjusted on the model simulation. The reaction of N₂O formation as a byproduct was considered to reproduce the behavior of the temperature rise test in a CO+NO atmosphere.

In recent years, Spark-Ignition engines with direct injection (DI) have become mainstream in response to tighter automotive emission regulations and the need to become carbon neutral. The gas temperature is low during cold start, so reducing methane emissions which has lower catalyst purification rate at low temperature is effective. In this study, the methane emission characteristics related to three fuels with different characteristics were analyzed using chemical reaction simulations and actual engine tests. The results of computational simulation showed that the balance of reaction acceleration and reaction freezing affected the amount of methane emission related to methyl radical. In the actual engine test, physical properties of the fuel types also affected the amount of methane emission.

In diesel engines, mixture formation of fuel and air is closely related to the formation of a spray flame. The relationship of the behavior between an evaporated fuel spray and a spray flame needs to be clarified for further improvement of thermal efficiency in the diesel engine. However, it is difficult to measure the in-plane velocity field of a spray flame using the PIV method because it is impossible to separate the scattered light from the tracer particles and the luminous flame. In this study, the flow characteristics of an unsteady spray flame were experimentally investigated by obtaining the velocity field inside its flame with typical PIV. Oxygenated fuel was used as test fuel in order to suppress the light intensity from the luminous flame. The velocity field of the spray flame was compared with that of the evaporated spray. As the results, the axial velocity of the spray flame was higher than that of the evaporated spray. Furthermore, the normalized turbulent intensity of the spray flame regardless of the position in the flow direction and the injection pressure was smaller than that of the turbulent jet.

Particulate matter (PM) formed by combustion of hydrocarbon fuel has harmful effect on environment and human health. Therefore, it is required to reduce. In generally, the main component of PM is soot, and its precursor is thought polycyclic aromatic hydrocarbon (PAH). In this study PAH and PM formation by pyrolysis and oxidation of dodecane under low temperature condition (1073K～1323K) using a flow reactor were investigated under φ = ∞, 6.2 and 2.8 conditions. In addition, numerical analysis for PAH mass concentration was also performed using a CHEMKIN-Pro software. As a result, the lower amount each PAH was formed under higher oxidation concentration condition. The lower amount PM also formed under higher oxygen concentration. Therefore, it was found that the amount of both PAH and PM under with oxygen condition was lower than under without oxygen condition.

Nanometer size Particulate Matter (PM) exhausted from internal combustion engine is one of the major air pollutants, and its reduction technologies are required. In this study, to clarify characteristics of PM formed by flame quenching process, a laminar pool flame of toluene was quenched using a slide and rotary metal mesh system, and PM exhausted by quenching process was analyzed. Activation energy of PM at various quenching position in the flame were measured by a thermo gravimetric analyzer. As a result, it was found that oxidative properties were differed depending on quenching position. Initial oxidation temperature of soot contained in PM raised with an increasing of quenching position. In addition, by quenching the flame using a metal mesh, PM with a low activation energy of oxidation was exhausted.

In this study, PM exhausted from unsteady pool flame of iso-octane on a shallow dish under various ambient temperature conditions (25 – 700°C) was investigated as fundamental study of fuel film combustion. In addition, PM emissions from the flame of fuel contaminated with lubricating oil were also investigated. Flame appearance from ignition to extinguishment under various ambient temperature conditions was observed. Further, total mass of PM emitted from the flame during flame formation period were measured by a filter method. In addition, real-time PM number concentration measurement was carried out by a Pegasor Particle Sensor (PPS-M). As a result, it was found that total mass and number of PM from pool flame of iso-octane was higher than that of iso-octane with lubricating oil (5wt%). Further, for lubricating oil content condition, deposit on the shallow dish was observed after flame extinguishment.

This study aims to get a foothold in the practical application of an ANN (artificial neural networks) aided parameter identification method. Using measurement data obtained from a real engine of commercially available cars, the authors tried parameter identifications for a zero-dimensional theoretical heat balance model of the engine system with the ANN-aided identification method. The identification results show that each heat conductance is a function of coolant and oil follow rates, and heat capacity is also a function of those flow rates. The numerical simulation of the representative temperature of the engine system using the theoretical model with identified parameters shows pretty good predictions.

Flames stabilization mechanism and the structure to enhance the stability of lean premixed methane-air flames were investigated using a coaxial dual nozzle burner. A lean premixed diffusion combined flames is created by forming a lean premixed flame in the inner main burner and a diffusion flame in the outer annular burner. The combined flame significantly improves the blow-off limit compared with the single lean premixed flame. The combined flame can be classified into three distinct shapes by organizing the flame length by the equivalence ratio. In any of these regions, the key to flame stabilization lies at the base of the combined flame where the diffusion and lean premixed flame connect.

Flame stability of combined flames formed in a co-axial dual nozzle burner consists by main burner and annular burner have investigated experimentally. Lean premixed methane air mixture issued from the main burner while pure methane gas flow from annular pilot burner. By using the pilot burner, blow-off limits of the lean premixed flame can be extended drastically. The diffusion flame encountered with the lean premixed flame works as a booster and forms the combined flame. Then, the structures of combined flames can divide into three distinct flame shape, lifted flame, tip open flame and rim stabilized flame. In the lifted flame, the lean premixed flame lifts by the pilot diffusion flame and forms to separate from the burner rim. In the lifted space, mixing zone for the lean premixed gas and fuel from the pilot burner. The boost fuel from the pilot burner plays a key role for the stability of the lean premixed flame.

Methanation is a technology that synthesizes CH₄ from CO₂ and H₂. This technology is being developed as CCU (carbon capture and utilization). Because methanation is an exothermic reaction, a high CH₄ yield can be obtained by improving the reaction rate at low temperatures, and at the same time, the reaction can be self-sustaining without external heat supply due to its own heat generation. In this research, we worked to develop a low-temperature, highly active reaction process and elucidate the reaction mechanism by applying non-thermal plasma to a catalyst packed bed (4.7 wt%-Ni/γ-Al₂O₃: 20 g). The use of non-thermal plasma to the methanation reaction (total flow rate: 3000 mL/min) has a clear reaction promotion effect in the temperature range below 370 ℃ compared to thermal catalytic reaction, and at an environmental temperature of 200 ℃ the reaction efficiently reaches an equilibrium state with a small SEI (specific energy input) of 8.80 kJ/mol. We established an experimental method to distinguish the radical reaction and thermal effect. We confirmed the onset temperature, defined as the temperature at which 5 % CH₄ yield is achieved, decreased by 33 ℃ (228 ℃→195 ℃) due to the radical reaction. We also confirmed the autothermal methanation where the methanation is initiated from ambient temperature.

Oxygen-hydrogen combustion power generation is a promising large-scale, highly efficient power generation technology for a decarbonized society. Oxygen-hydrogen combustion requires high-pressure and high-purity oxygen produced by cryogenic air separation. However, for oxygen production using cryogenic air separation, a large amount of power is consumed for both air compression and oxygen compression, leading to a decrease in net thermal efficiency. In this study, we used the process simulator Aspen Plus to analyze the effect of reducing specific energy consumption in high-pressure oxygen production by cryogenic air separation using liquid hydrogen cold energy and liquid-phase pressurization of oxygen. Compression of oxygen in the liquid-phase was shown to reduce compression power by 99.1 %, 98.2 %, 97.7 %, and 96.7 % at 30, 70, 100, and 150 bar, respectively, compared to compression in the gas-phase. Furthermore, it was shown that the specific energy consumption can be reduced by 44 %, 38 %, 34 %, and 30% at 30, 70, 100, and 150 bar, respectively, by using the liquid-phase pressurization of oxygen and hydrogen cold energy.

The supercooling dissipation technology is indispensable for supercooled heat storage, which is a type of natural energy, and the clarification of the freezing mechanism of heat storage materials is inevitable for the establishment of the technology. Previous studies have shown that an electric field is effective in this method and that direct contact heat transfer between water and silicone oil enhances heat transfer. In the experiment, a wire electrode was placed in the center of a cylindrical electrode and its diameter was varied to observe the behavior of water droplets in an electric field. As a result, it was found that the presence or absence of a water column generated when a water droplet contacted the wire electrode changed.

Electronic devices are becoming smaller and more powerful, and the amount of heat generated is increasing. Boiling cooling is an effective cooling method to solve this problem. In order to enhance the heat transfer performance of boiling cooling, research has been conducted to increase the generation of bubbles by forming minute scratches or depressions on the heat transfer surface. One method of forming depressions on heat-transfer surfaces is a metal 3D printer, which is a layered modeling technology. In metal 3D printers using laser sintering, fine particles are sintered and laminated, and depressions are formed on the laminated surfaces, which may serve as bubble nuclei. In this report, we observed the aspect of boiling on the laminated surfaces by metal 3D printers and the condition of the laminated surfaces. As a result, it was found that the depressions between laser sintering marks may function as bubble nuclei.

Solid-liquid phase change of LiCl-KCl binary mixture has been visualized by electrical resistance tomography (ERT). The conductivity distribution was derived from iterative absolute value reconstruction model. In order to calculate the solid volume fraction distribution, conductivity was converted to solid volume fraction distribution. In the experiment, the initial temperature was set at 700℃ and was lowered at a rate of 4.44℃/min. As the results, solidification of molten salt was seen around 500℃ at the near field of crucible wall. On the other hand, solidification was not observed until under 400℃ in the center of crucible.

The purpose of this experiment is to create a circulation system that generates hydrogen using a redox reaction between zinc and water. The Ellingham diagram shows that the reduction of metal oxides depends on temperature and oxygen partial pressure. The experimental results revealed that the longer the combustion time at the same temperature, the higher the reduction rate. Additionally, it was confirmed that the reduction rate depends on temperature, as expected. When comparing stainless steel tubes and quartz tubes, it was found that the reduction rate of quartz tubes was better than that of stainless steel tubes across all temperature ranges.

The purpose of this research is to establish a hydrogen production/reduction cycle using solar energy. This cycle is based on the zinc oxide redox system. Sunlight is focused by a Fresnel lens and used as a heat source. When zinc oxide and carbon are heated in a reaction tube, the zinc oxide is reduced to form zinc. Zinc and water react to produce hydrogen. This time, we conducted the experiment under atmospheric pressure rather than under a vacuum atmosphere. As a result, the amount of hydrogen obtained was 347mL when using an electric furnace, and 107mL when using sunlight.

Small wind power generation is expected as the development of new energy sources accelerates. Therefore, this study focuses on contra-rotating propeller wind turbines, which are suitable for operation under internal flow conditions, and aims to increase the output of small wind turbines. Specifically, we investigate the performance characteristics of the contra-rotating propeller wind turbine by numerical flow analysis using a model with the contra-rotating propeller installed inside the pipe. In this paper, we focus on the NACA airfoil, and show the results of investigating their performance characteristics and internal flow by numerical analysis.

In order to effectively utilize unused hydraulic resources in irrigation channels, simple water supply systems, it is essential to improve the performance and reduce the size of small hydroturbines. Previous research has revealed that the tip clearance has a significant effect on the performance of this test turbine. Therefore, we conducted a numerical analysis and experiment to investigate the effect of changing the tip clearance of a small hydroturbine with a diameter of 49 mm (D49 model) on performance and report the results here.

In order to develop an in-line small hydroturbine that can generate 300W at a small flow rate of 3l/s, we adopted a contra-rotating rotors to achieve both miniaturization and high efficiency of our hydroturbine in this study. A centrifugal rotor that can be applied to small flow rates and high heads is used for a front rotor, and a hybrid rotor that combines a mixed flow rotor and an axial flow rotor is used for the rear rotors with the propose of recovering the same head as the front rotor. In this study, a volute was employed to inject pre-swirl into the front rotor. In addition, the number of blades, exit angle, and rotation speed of the front rotor were changed, and numerical flow analysis was conducted to improve the performance of the front and rear rotors.

In response to global warming and the depletion of petroleum resources, carbon neutrality policies have led to increased integration of renewable energy sources. However, the variable nature of renewable energy, particularly solar power, presents challenges for stable energy supply. This study aims to smooth electricity demand through a game theory-based scheduling method for energy consumption, specifically addressing inefficiencies caused by fluctuating power demand throughout the day. By integrating electric vehicles (EVs) as dynamic batteries, this approach seeks to optimize energy usage and reduce peak demand periods. A MATLAB simulation targeting households and workplaces demonstrates that such a scheduling system can lower user electricity costs while evening out the demand. The study employs a model where users shift the usage times of their appliances based on cost functions, ensuring electricity consumption is balanced. The results indicate a reduction in the peak-to-average ratio (PAR) and overall electricity costs, illustrating the potential of this method in achieving efficient energy management and demand smoothing without the direct integration of EVs into the power grid.

In order to capture approximately 10 vol% of carbon dioxide contained in the combustion flue gas, a technology that absorbs carbon dioxide into a solution and then reacts it with calcium to solidify it is gaining attention. The challenge of this technology lies in not only recovering carbonate ions by reacting them with calcium but also regenerating the absorption liquid (alkaline aqueous solution) to establish a system that absorbs and fixes carbon dioxide. In this study, we report the results of investigating the feasibility of a cycle system where carbon dioxide is captured from air containing 5-10 vol% CO2 using an alkaline aqueous solution as the absorbent and recovered by reacting with Ca(OH)₂ to form carbonate.

Methanation technology is a low-carbon technology that represents CCU and is in urgent need of commercialization. It is important to realize this technology at the lowest possible temperature due to the limitation of thermal equilibrium, and it is also necessary to develop a compact, decentralized technology that is connected to renewable energy and can handle high load fluctuations. The objective of this study is to construct a low temperature methanation reaction using non-equilibrium plasma and catalysts. To elucidate the reaction enhancement mechanisms, the effect of active species on gas-phase and surface reactions was clarified using in situ FTIR, which enables diagnostics of catalyst surface reactions under the action of plasma. The diagnostics revealed that the amount of CH₄ production in the methanation can be improved by cooperating gliding arc discharge and Ni/Al₂O₃ and the cause of the improvement is the accelerating of bidentate formate decomposition under gliding arc discharge. In addition, we found that the generation of active hydrogen by gliding arc discharge assists in the efficient decomposition of bidentate formate.

Atmospheric pressure micro plasma jets, which form thermally nonequilibrium discharge plasma in the form of jets, are expected to be applied to medical and environmental technologies. When the structure of the discharge tube jet nozzle is a double coaxial pipe, an independent plasma jet is formed in the inner and the outer layer, and these are synthesized at the nozzle outlet, enabling control from electrical, thermal, and fluid engineering aspects. In this study, we succeeded in using Ar gas as the working gas, generating an atmospheric pressure micro plasma jet by using the double coaxial pipe structure. Then, gas flow velocity in two layers, applied voltage, and distance between electrodes were changed, the controllability in the generation of this plasma jet and its characteristics were investigated. As a result, it has been clarified that this generation method of micro plasma jet is effective by properly controlling condition for various applications.

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 WT biofuels (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 WTB, 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%.

In this study, in order to design a coating film with arbitrary orientation and high reflectance in the near infrared region, we numerically analyzed the effect of the non-sphericity of pigment particles in the coating film on the scattering and absorption characteristics. Regarding measures to suppress the heat island effect. From the numerical analysis, we calculated the radiation characteristics of non-spherical pigment particles using electromagnetic field analysis by the FDTD method. As a result, it was found that non-spherical shapes exhibit radiation characteristics not seen in spherical shapes.

The goal of this study is simultaneous concentration and temperature imaging of acid-base neutralization reactions. As part of the process, we estimated the concentrations of acids, bases, and salts. The absorbance difference spectra of aqueous HCl, NaOH, and NaCl solutions were obtained by FT-IR at different concentrations and temperatures. From the absorbance difference spectra, the wavelengths of high importance were selected, and multiple regression analysis was performed to generate a regression model. The experimental apparatus was a Y-shaped microfluidic chip, in which an aqueous HCl solution with low density flowed from the upward and an aqueous NaOH solution with high density flowed from the downward. Transmitted light images of the flow were obtained by a near-infrared camera. Subsequently, the concentration of each component was imaged. The concentration profiles of the HCl and NaCl solutions were not accurate, indicating the need for more precise profiling.

An elastic-plastic pipe support is defined as a pipe support structure that supports the own weight of the pipe and allows plasticization against seismic loads that exceed the design assumption. An increase in damping based on energy absorption by the plastic hysteresis loop can also be expected. This study presents the damping characteristics of elastic-plastic pipe supports and the relationship between the ductility factor and the response reduction effect that can be expected from the seismic design of piping systems with elastic-plastic pipe supports. For the elastic-plastic pipe support made of steel, which assumes a load displacement relationship of a bilinear approximation, the damping ratio of up to 18% can be expected as a support alone. Moreover, the effect of reducing the seismic response on the piping system was maximized before the ductility factor of the elastic-plastic pipe support reached 4, and thereafter it was decreasing.

A seismic design procedure of piping system which is based on the detailed inelastic time history analysis has been published as the JSME Code Case in 2019. In this Code Case, the elastic-plastic behavior occurred in pipe body is considered, whereas pipe support structures are assumed to remain in the elastic region. To incorporate the effect of the inelastic behavior of pipe support structures into the JSME CC, the authors has launched a series of benchmark analysis on pipe support structures. The benchmark analysis of pipe support structures consists of two main stages; the first stage is the analysis of pipe support structures themselves, and the second stage is the analysis of piping system with inelastic pipe support structure. The result of the first stage of the benchmark analysis indicates that differences in boundary conditions affected the load-deflection relationship of the support structures. For the second stage of the benchmark analysis, the analytical object has been decided, and the plan of the benchmark analysis is now under discussion.

The effective mass of content liquid for tank rocking motion used in the equation of motion of the Taniguchi model was reviewed. The effective mass of content liquid for tank rocking motion is defined based on gradient of hydrodynamic pressure due to angular acceleration of tank rocking motion, and it is used for both the moment inertia term and the restoring moment term of the Taniguchi model. However, using the effective mass of content liquid for tank rocking motion in the restoring moment term may not be appropriate. In this study, the effective mass of content liquid for the restoring moment term was redefined based on hydrostatic pressure resting on uplifted area of the tank bottom plate. As a result, calculation accuracy of the Taniguchi model was improved.

Natural hazard triggered technological accidents are defined Natech as an acronym. In these days, with the rise of interest of safety on general industrial plants, the importance of Natech and Natech based safety assessment are well-recognized. For continuous improvement of safety, it is necessary that the assessment of Natech based on realistic damage modes on the components in the plants. However, because of the lack of knowledge, the relation between the maintaining function and the damage modes are not clear. Therefore, this study has been investigated the damage modes of piping, especially it has been focused on elbow under seismic motion beyond design level. The shaking table tests on a simple shape piping system with dead-weight has been conducted. In the experiment, mass of the weight and input acceleration level were considered as parameters, and the results are mapped to clarify the change of failure modes. In this paper, the summary results of the tests are described.

The power transmission line that supplies power to the neutral beam injector (NBI), one of the plasma heating devices in ITER, consists of a 1.7 m in diameter pressure vessel filled with insulating gas for electrical isolation and containing multiple low-flexible conductors, and is required to have a radiation confinement function. During an earthquake, the power transmission line connecting from the super high voltage generator located outside to the seismically isolated tokamak building is subject to relative displacement. In order to maintain the radiation confinement function of the transmission line, a seismic relative displacement absorber consisting of a horizontal and vertical bellows system and seismic isolation elements such as coil springs and viscous dampers has been developed. The bellows system is required to absorb the displacement of ±300 mm in the horizontal direction. Furthermore, the seismic feasibility of the developed structure was confirmed by seismic response analysis.

This paper examines the applicability of the hot spot method using a small wireless system and the effect of data loss during data communication on fatigue evaluation. It is not practical to monitor all structural members, it is important to monitor the structural integrity of damage-prone areas. In addition, due to cost and installation space constraints, the use of inexpensive, compact IoT devices is effective. Small wireless fatigue monitoring methods using strain gauges have been proposed, and systems based on the nominal stress method have been considered. However, there are cases where the nominal stress cannot be defined due to the complex structure of the weldment. In such cases, the hot spot method, which measures the structural stress concentration, is effective. However, the application of the hot spot method to a small wireless monitoring system has not been sufficiently studied. In this paper, a small wireless monitoring system was fabricated and its applicability to fatigue evaluation of welded joints was confirmed. From the test results, it was confirmed that the data loss was caused by the data communication condition of the small wireless system and the accumulated fatigue damage degree was underestimated. It was also confirmed that an appropriate small wireless monitoring system should be selected considering the information on fatigue and stress conditions required for the target structure.

Mechanical seals are used to prevent leakage of liquids and gases in rotary mechanisms in various industrial fields. A mechanical seal consists of a rotating ring and a stationary ring, which make a surface contact. Mechanical seals could generate friction-induced vibration under rotary sliding motion, leading to unexpected noise. The uncomfortable sound significantly decreases the product value even if the sealing performance is acceptable. Tadokoro et al. proposed an anti-vibration method using Yaw Angle Misalignment effect (YAM method), which applies a parallel misalignment to a rotary sliding system, leading to suppress friction-induced vibration. In this study, to investigate the effect of the YAM method on suppression of friction-induced noise in mechanical seals, the YAM method was applied to two types of mechanical seals in which the rotating ring was the source of vibration and mechanical seals in which the stationary ring was the source of vibration.

In this study, we propose a new vibration isolation device using hydrostatic effect. The proposed device supports an object with a piston combined with a cylinder. The proposed device consists of a variable restrictor whose fluid resistance depends on the position of the piston, a fixed restrictor whose fluid resistance does not depend on the position of the piston and a narrow annular gap between the piston and the cylinder acts as a hydrostatic gas bearing. The hydrostatic gas bearing guides the piston movement in vertical direction and it also acts as a fixed restrictor. All restrictors are slit-shaped and flow in there can be assumed as laminar. The larger the rate of change of the resistance of the variable restrictor to the displacement of the piston, the larger the static spring constant. If the static spring constant is larger than that of an equivalent air spring, the damping coefficient will be negative and the vibration isolation device will be unstable. Under conditions where the damping coefficient is positive, the smaller the static spring constant, the larger the maximum value of the damping coefficient. By increasing the static spring constant within a range that does not exceed the allowable value of the resonance frequency and the allowable value of the resonance magnification, under the condition of an equivalent damping ratio that minimizes the resonance magnification, it is possible to reduce vibration over a wide frequency range.

The standards and guidelines of FEMA, ASCE, and Eurocodes specify methods for evaluating the seismic performance of structures. However, they do not provide specific methods for detecting structural damage. In this paper, we demonstrate that a specific structural health monitoring method. Existing methods detect damage based on temporal changes in the natural frequencies of structures. Therefore, if the changes in natural frequencies are small, damage detection becomes difficult. Our proposed method differs from existing methods by considering the correlation between the response acceleration of the structure and the input acceleration. Based on the physical reference values set for the response acceleration and the input acceleration, we synthesize their time-frequency relationships. The synthesized data have three-dimensional information of intensity, frequency, and time. From this data, we create three types of image data with different characteristics. Using these three types of image data, we evaluate structural integrity through a deep learning model based on Bayes' theorem. The effectiveness of our method was verified through analytical and experimental data. The results of verification using analytical data revealed that considering the correlation of input and output accelerations enables more precise structural integrity assessment. Additionally, verification using experimental data confirmed the applicability of our method to actual structures.

An electromagnetic damper is a one of the semiactive dampers which can control a damping force, and has been researched a lot before. It has conventionally a DC motor in order to get a damping force for converting a rotational kinetic energy into an electrical energy by the motor and dissipating. The damping force can be controlled by switching a resistance of the motor terminal. In this paper, the authors propose to use a stepper motor instead of the DC motor to find some new performance. A proto-type damper using 2-phase or 5-phase stepper motor was manufactured, and the resisting force characteristics of the damper were measured during sinusoidal vibration. Finally, a performance of the damper was confirmed experimentally.

This study aims to compare the performance of tuned mass dampers (TMD) and inter-story damping devices to contribute to the optimal selection of vibration control devices. With the advancement of vibration control technology, various damping devices have been developed. Oil dampers, which absorb vibration energy using the viscous resistance of fluid, are widely adopted in many structures. In this study, the performance of TMD and rotary inertia dampers is evaluated with oil dampers as a benchmark. Specifically, the reduction effects of RMS and peak responses are analyzed, comparing the characteristics and advantages of each vibration control device using time response analysis. This will help address current issues related to the installation and maintenance of these devices and enhance the seismic performance of buildings.

Elevator ropes installed in high-rise buildings may resonate with the vibration of the building by long-period ground motions due to the natural periods of the rope and the building being close to each other. This resonance phenomenon can result in damage such as collisions or snagging of ropes on equipment in the elevator hoistway. This makes it difficult to continue using the elevator, and can also result in secondary damage such as preventing smooth evacuation and transportation of injured people during earthquakes. To reduce vibration damage caused by ropes, it is necessary to clarify the seismic response of ropes. In this study, a seismic response analysis using the finite difference method was conducted on an elevator rope installed in an apartment building. The analysis results show that higher-order vibration modes appear as the rope gets longer. This can be used to select the evacuation floor to prevent the rope from resonating.

Sedimentation device with inclined plates used in sedimentation tanks of water purification plants are often damaged by earthquakes, and the damage is caused by sloshing in addition to seismic response. In this study, the vibration control performance of a steel damper developed to prevent sloshing of sedimentation device with inclined plates was confirmed through vibration tests. A water tank containing a full-size inclined plate was vibrated by actual seismic waves, and various data were collected from sensors installed on the damper and inclined plate. As a result, the damper exhibited vibration control performance when sloshing occurred, and the occurrence of sloshing was suppressed. It was also confirmed that the damper suppressed damage to the sloping plate itself. The number of dampers installed and the thickness of the damper also made a difference in the damping performance of the damper. From these results, it was found that the damper is useful as an anti-sloshing measure.

This paper deals with vibration damping analysis using finite element method (FEM) with Strain Energy Method for rib structures having acoustic black holes at both sides at of the plate. This rib model has acoustic black holes at both sides. Damping materials are laminating on the acoustic black holes. And the rib structure is supported by linear spring in the middle of the model. We calculated 1 st~50 th order mode of modal loss factors and eigenmodes of the models by using FEM. And we select 10 modes with similar deformations between two models. The base model is a rib structure with acoustic black holes at both sides and a damping material at the top, and the comparison model is a rib structure without acoustic black holes and with only a damping material. We clarified the effect of the acoustic black hole on the modal damping for each eigenmode. As a result, it became clear that the value of the modal loss factor increased significantly by adding acoustic black hole. In particular, it is found that fixing both sides where the acoustic black holes are located increases the damping of low-order modes.

Vibration and noise reduction is an important industrial and environmental technology for comfortable industrial products and safe structures. In this paper, numerical simulations of the damped vibration of a structure with a porous layer sandwiched by a double wall are presented. The cover plate in double-walled structure has two Krylov-type acoustic black holes. The other side edges of the wall are fixed. Vibration-damping materials are installed on the black hole surfaces. Numerical analysis was performed using the FEM and MSKE methods proposed by Yamaguchi et al. to clarify the changes in vibration transmission from the base plate to the cover plate due to multiple acoustic black holes. The base plate was not affected by the effects of the acoustic black holes. For the cover plate, vibration was transmitted to the acoustic black holes and damping effects were obtained. It can be seen that fixing the cover plate increased the damping effects in the low-frequency band and decreased the damping effects of the acoustic black hole in the high-frequency band.