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It is known that the sound absorption performance of resonant type acoustic liners is affected by glazing flow, which interferes with the motion of fluid particles. In order to prevent the effects of glazing flow, we propose new design concepts, which apply with a special thin film called Fine-Perforated-Film (FPF) to the surface of the acoustic liners. We made two types of liners. Typical resonant type acoustic liners are “Baseline” which has round holes and “V-Slit” which has slit holes. New resonant type acoustic liners have a gap fixed between the FPF and “Baseline” liner surface. Each liner was tested using the flow duct rig of Japan aerospace exploration agency (JAXA). From the data obtained, the sound absorption coefficient Δ and the drag coefficient were calculated. The results show that the drag coefficient can be reduced without changing the sound absorption coefficient by changing the hole shape of the FPF. It is suggested that small hole size of FPF reduces the peak value of the sound absorption coefficient and the drag coefficient. These results show that acoustic liners combined with FPF can be superior to conventional acoustic liners in both acoustic and aerodynamic performance. To find the mechanism of drag reduction due to hole shape change, we performed visualization tests using PIV on acoustic liner models. It was found that shortening the length of the hole in the flow direction suppresses the flow into and out of the cavity and reduces the occurrence of turbulence.

Controlling frictional drag, noise, mixture, and chemical reaction in flow is an important issue in various engineering fields. In recent years, many investigations have been carried out to control the frictional drag by external stimuli, such as light and electricity, from the point of view of rheology and physical property. Flow control by the external light stimulus has a great advantage in that there is no contamination of the flow field. Some experiments of a photoresponsivity surfactant solution CTAB/C4AzoNa have been conducted for the basic study of flow control. The viscosity of the surfactant solution increased with the irradiation of ultraviolet (UV) light and decreased with visible light. First, we attempted to control the vortex height in the rotating flow by irradiating with UV and the visible light. The vortex height repeatedly increased and decreased by the reversible change in viscosity of the CTAB/C4AzoNa solution. Next, a thin layer of this solution in a vessel was exposed to blue laser sheet irradiation of 405 nm wavelength. As a result, the viscosity of the CTAB/C4AzoNa solution in the thin layer was locally increased at only the irradiated portion of the laser sheet. Finally, the CTAB/C4AzoNa solution filled a thin gap of the rotating two axial cylinder represented as a simple shear flow model. The torque acting on the inner cylinder surface was changed by local UV irradiation. These results proposed that this surfactant solution has the potential to achieve local and reversible flow control of drag.

This paper describes computational study to investigate the aero-acoustic mechanism observed in Hartmann generator when under-expanded supersonic jet is blown from a convergent nozzle. The Hartmann generator, composed of a nozzle and a resonance tube with small distance, is known to radiate much higher amplitude of tonal sound than a free jet without any interaction. Aiming at establishing compact and efficient fluidic actuators, the authors tried to clarify the fluid-dynamic and acoustic behaviors of this special device by use of computational tool, i.e., UPACS-LES of Japan aerospace exploration agency（JAXA）. The computational results suggested existence of the JRG mode, an alternative flow motion between the nozzle and the resonance tube. This flow motion drives strong pressure fluctuation and forms sound field in the far field. The computational results complied with the fundamental acoustic characteristics in the former studies, such as far-field sound directivity and radiated acoustic power. Based on the results, it was confirmed that some parameters such as nozzle pressure ratio are predominant to intensify the acoustic power in the far field. Especially, the open-end location of the resonance tube governs the acoustic power when it is between Mach disk and shock cell end in the under-expanded supersonic jet.

In the installation process of an elevator, work performs to correct the bending of the rail in order to suppress the lateral vibration of the car due to the irregularity of the guide rail. In this work, each rail bracket is adjusted so that the cutting edge of the rail is in the specified horizontal position with respect to the piano wire. However, since the rail is bent at the joint, irregularities remain even if the brackets are lined up in a straight line. Such a method cannot suppress the lateral vibration of the car and may worsen it. In this research, we proposed a method of optimizing the rail shape to minimize the vibration of the car based on a rail behavior model in that adjustment process and a car vibration model. The effect was verified in an experiment using an actual elevator. In the elevator system, large vibration had been occurred because the periodic excitation force determined by the running speed and rail bending period matched the natural frequency of the car. By adjusting the rails based on proposed method, we avoided resonance and reduced lateral vibration by 37%. This verification showed that the use of the proposed method enabled significant vibration reduction in a short period of time.

Automated driving is attracting attention as a technology that can improve the convenience and comfort of mobility. Research on automated driving continues to develop not only in the approach of vehicle automation but also in the approach of driver assistance. As an example of driver assistance technologies, a system has been proposed in which multiple light sources are placed at equal intervals in a tunnel and blink to encourage drivers to adjust their speed. This system is called a Pace Maker Light (PML). In this paper, we focus on the PML and consider applying it to automatic driving. Therefore, this paper aims to realize the velocity control of an autonomous mobile robot using the PML. First, we modeled the PML and the mobile robot and formulated the design problem of the velocity controller of the robot. Then, we proposed a control law that can achieve velocity control based on the light intensity information obtained from the PML. Finally, we conducted velocity control simulations and experiments with a miniature-scale experimental setup. As a result, it was confirmed that the proposed method could be used to achieve the target speed on a level road and a slope.

This paper describes an experimental study on inlet distortion in the flow ingested to an intake of a ducted fan. Recent high bypass ratio engines tend to shorten the nacelle length for better fuel consumption. In return, the shorter the nacelle intake, the more intensive the inlet distortion inside the intake, which leads to deteriorating fan aerodynamic performance and intensifying the fan noise. This study aims at understanding the influence of intake geometries on the distortion ingested to a ducted fan and thus the fan noise caused by the interaction of the distortion with the fan blades. A subscale fan (fan simulator) coupled with intake models were used in the experiment. The intake models with different axial lengths were prepared to compare the distortion in front of the fan. One is a nominal intake as a reference. The other intake has a short non-dimensional distance from the lip to the fan surface. Crosswind conditions were imposed to realize a clearer influence of the distortion on the acoustic and aerodynamic parameters. According to the experimental results, the intake models provided a distinct increase in sound pressure levels inside the intake. It is anticipated that the sound amplification is attributed to the distortion associated with the intake lip geometry, intake length, and crosswind speed. Non-dimensional total pressure distribution revealed the high correlation between the fan noise and the inlet distortion.

Parametric speaker can radiate an audible sound beam with sharp directivity by using the nonlinear interaction of ultrasonic waves. In recent years, the highly directional audible sound generated by the parametric speaker has been applied to various applications. For example, applications such as active noise control, sound absorption coefficient measurement, and creation of audio spots have been proposed. Numerical analysis of nonlinear sound field is important in application design. Many discrete analyses by using finite difference time domain method have been proposed as analysis methods for parametric speakers, but these methods have problem that the calculation load is heavy. Therefore, there is a need for efficient analysis methods for parametric speakers. In this study, we construct a steady-state response analysis method that can efficiently analyze the audible sound of parametric speakers. The method is combined a nonlinear concentrated mass model and a perturbation method. In addition, the computational load of the constructed model can be reduced by combining the substructure synthesis method. The proposed method is suitable for analysis of parametric speakers because the number of divisions in the axial direction can be set very large. The validity is confirmed by comparing the analysis result of the proposed method with the solution of the KZK equation. In addition, the improvement in calculation efficiency by the substructure synthesis method has been confirmed by numerical calculation.

In nuclear power plants, measures against radioactive noble gases are required. Until now, special activated carbon that easily adsorbs noble gases has been used in some nuclear facilities. However, activated carbon has a small adsorption capacity and is greatly affected by other gases and environmental humidity. Therefore, it is necessary to develop a new adsorbent with high adsorption performance. At emergency response stations, it is also necessary to take measures using air cylinders. It was confirmed that the newly developed silver zeolite XeA has more than 10 times adsorption efficiency of activated carbon for noble gas adsorption. In this paper, we will report on the basic noble gas adsorption performance of XeA and compare the adsorption performance between XeA and activated carbon. In addition, some applications of the noble gas adsorbent XeA are recommend, for example, (1) applied to noble gas countermeasures at emergency response stations, (2) applied to activated carbon noble gas hold-up systems, and (3) applied to emergency gas treatment systems (SGTS). Since silver zeolite XeA has excellent noble gas retention performance, it is possible to reduce the size and simplification of equipment by using it instead of the existing activated carbon. Furthermore, since XeA is nonflammable, it can be expected to improve safety.

A prediction model of the fluid force on a cylindrical blade driven by the Necklace vortex is developed and verified by experiments when the yaw angle is given. Based on the measurement results of the velocity ratio of blade and wind velocity and the fluid force coefficient at zero yaw angle, a prediction model for the relationship between the rotation angle of the cylindrical blade and the fluid force coefficient considering the yaw angle was derived from the analysis of the two-dimensional velocity components acting on the cylindrical blade. The validity of the predictive model was demonstrated by experimental verification. From the comparison, it was found that there was a time delay in the formation and disappearance of the Necklace vortex. Based on the experimental results, the characteristics of the fluid force acting on the cylindrical blade were classified into five angular regions and based on the characteristics of the effective velocity ratio considering the yaw angle, the classification was made into 12 angular regions. Depending on the yaw angle, wind speed, and rotational speed of the blade, all of these regions may appear or only some of them may appear. Therefore, the yaw angle characteristics of the cylindrical blade wind turbine driven by the Necklace vortex are very complicated.

Through the research of Filtered Containment Venting System (FCVS), air purification methods have been developed, such as technologies of scrubbing, metal fiber, silver zeolite and mobility. Using these technologies, we have been studying the further improvement of air purification systems in the nuclear field. In this study, we conducted adsorption experiments using several metal fiber filters and evaluated the effect of the metal fiber wire diameter on the decontamination factor (DF). It was found that metal fibers with fine wires made a significant contribution to the removal of materials with minute particles. By combining the metal fiber technology with the scrubbing technology, a sufficiently huge DF could be achieved on a laboratory scale. Based on these results, we can propose the mobile air purification system.

Lecanemab is a humanized monoclonal antibody directed against human soluble amyloid-β aggregates. It was developed for the treatment of early Alzheimer's disease (mild cognitive impairment or mild dementia stage of Alzheimer's disease). Among the amyloid-β (Aβ) involved in Alzheimer's disease, Lecanemab selectively binds to the highly neurotoxic Aβ protofibrils, and is thought to reduce Aβ protofibrils and amyloid plaques (Aβ plaques) in the brain. The efficacy and safety of Lecanemab in early Alzheimer's disease were investigated in an international Phase II placebo-controlled study (Study 201) and an international Phase III placebo-controlled study (Study 301). Both studies included Japanese subjects. Lecanemab was given accelerated approval in the United States in January 2023, followed by traditional approval in July 2023. In Japan, it was approved for "control of the progression of mild cognitive impairment or mild dementia stage of Alzheimer's disease" in September 2023, and was added to the NHI drug price list in December 2023. [ABSTRACT FROM AUTHOR]

Synthetic fuel derived from renewable energy is expected as a means of reducing CO2 in internal combustion engines. OME (OxyMethylene Ether) can be handled like a diesel fuel because its specification of distillation is almost same with it. Therefore, it is expected to introduced in the market as alternative or additional fuel. In this report, fuel properties, engine performance, combustion characteristics and exhaust emission of OME and its diesel blended fuels were investigated. The energy density was decreased with increasing of OME blending ratio because the energy density of OME is lower than that of diesel fuel. Since OME fuel has the effect of expanding rubber materials, an immersion test of rubber material was conducted with OME blending diesel fuel. As the result, exceeding permissible range was observed with beyond 10% OME blending. Engine power was decreased under same injection quantity condition with increasing OME blending ratio because of its lower energy density. In the test under the same torque condition, blending OME with diesel fuel resulted in deterioration of thermal efficiency and reduction of SOOT, HC, and CO emissions.

The fuel generated from CO2 and H2 derived from renewable energy is called “e-fuel”. Among the e-fuels, polyoxymethylene dimethyl ether (OME) is expected as a promising drop-in fuel for CI engines because it has good ignitability and low-soot combustion characteristics. However, the fuel properties such as density, heating value, and stoichiometric air-fuel ratio are different from those of diesel fuel. In this study, the spray and combustion characteristics of OME-diesel blends fuel were investigated and compared with diesel spray under engine-relevant condition at 920K-6.0MPa in a constant volume vessel. First, the fuel sprays were observed using high speed cameras under the non-reacting condition with O2 concentration of 0%. The result showed that spray-tip penetration length of OME-diesel blends was almost the same as diesel fuel, irrespective of the OME blend ratios, while the spray cone angle and spray projected area increased as the OME blend ratio increased. Moreover, the liquid phase length and width of OME spray were smaller than diesel spray. Then the reacting sprays were observed under the combustion condition with O2 concentration of 16% to understand combustion characteristics. The result showed that the ignition delay and the flame lift-off length were shortened as the OME blend ratio increased.