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Microbubbles coated by visco-elastic shells are important for ultrasound diagnosis using contrast agents, and the dynamics of single coated bubbles has been investigated in the literature. However, although a high number of contrast agents are used in practical situations, there has long been an absence of a nonlinear acoustic theory for multiple coated bubbles, except for our recent work by Kikuchi and Kanagawa ["Weakly nonlinear theory on ultrasound propagation in liquids containing many microbubbles encapsulated by visco-elastic shell," Jpn. J. Appl. Phys. 60, SDDD14 (2021)], under several assumptions to be excluded. Aiming for generalization, in this study, we theoretically investigate weakly nonlinear propagation of ultrasound in liquid containing multiple bubbles coated by a visco-elastic shell with compressibility. Leveraging the method of multiple scales, both the Korteweg–de Vries–Burgers (KdVB) equation for a low-frequency long wave and nonlinear Schrödinger (NLS) equation for a high-frequency short wave are derived from the volumetric averaged equations for bubbly liquids based on a two-fluid model and the up-to-date model for single coated bubbles with shell compressibility. Neglected factors in our previous paper, i.e., compressibility of the shell and liquid, drag force acting on bubbles, bubble translation, and thermal conduction, are incorporated in the present KdVB and NLS equations; the proposed model will be regarded as a generic physico-mathematical model. The results show that shell compressibility attenuated ultrasound strongly and decreased nonlinearity of ultrasound. Finally, we compared the magnitudes of six dissipation factors (shell compressibility, shell viscosity, liquid compressibility, liquid viscosity, thermal effect, and drag force) for five typical ultrasound contrast agents, and a similar tendency between KdVB and NLS equations was revealed. [ABSTRACT FROM AUTHOR]

In the art museum, lighting plays a crucial role in visitors' understanding and appreciation of exhibits. This paper mainly explores the influence of different lighting mode (general lighting, accent lighting, and mixed lighting) and correlated color temperature (CCTs) (4000 K and 2700 K) changes on the observers' psychology to find the best lighting environment. Based on the simulation carried out at the National Museum of Western Art in Japan, we made six diverse lighting designs. 31 observers were invited to evaluate each scheme, and the results of subjective evaluation were analyzed by means of one-way analysis of variance and the paired sample T-test. According to the results of data analysis, suggestions can be given for art gallery lighting design. It is not recommended to use general lighting alone in art museums, and it is better to use mixed lighting. When the CCT is 4000 K, only accent lighting can be used. When the CCT is 2700 K, the mixed lighting effect is better. [ABSTRACT FROM AUTHOR]

This paper reports on the design and characteristics of a compact module integrating an optical displacement sensor and an electromagnetic actuator for use with vibration–isolation systems installed in KAGRA, the 3-km baseline gravitational-wave detector in Japan. In the technical concept, the module belongs to a family tree of similar modules used in other interferometric gravitational-wave detector projects. After the initial test run of KAGRA in 2016, the sensor part, which is a type of slot sensor, was modified by increasing the spacing of the slot from 5 mm to 15 mm to avoid the risk of mechanical interference with the sensor flag. We confirm that the sensor performance is comparable to that of the previous design despite the modification. We also confirm that the sensor noise is consistent with the theoretical noise budget. The noise level is 0.5 nm/Hz1/2 at 1 Hz and 0.1 nm/Hz1/2 at 10 Hz, and the linear range of the sensor is 0.7 mm or more. We measured the response of the actuator to be 1 N/A and also measured the resistances and inductances of coils of the actuators to confirm consistency with theory. Coupling coefficients among the different degrees of freedom were also measured and shown to be negligible, varying little between designs. A potential concern about thermal noise contribution due to eddy current loss is discussed. As of 2020, 42 of the modules are in operation at the site. [ABSTRACT FROM AUTHOR]

Typhoon-induced P-wave microseisms can be observed using seismological arrays and analyzed for the seismic monitoring of ocean storms. This paper presents a frequency-domain beamforming (FB) method that integrates a three-dimensional (3-D) Earth model to better capture the heterogeneities in the subsurface structure, and therefore yield more accurate ray-tracing and travel-time predictions. This method is applied to the Super Typhoon Lupit (2009) using seismological array observations from the Northeast China Extended Seismic Array (NECESSArray) and high-sensitivity seismograph network in Japan (Hi-net). The results show that the localized P-wave microseism source regions based on the 3-D model are in better agreement with the theoretical source regions and typhoon centers than those based on a conventional one-dimensional (1-D) model. The significance of using a 3-D model instead of a 1-D model in the FB method is further investigated by comparing the consistency of the localization results for the two different arrays, with the localized source regions being more mutually concordant when using the 3-D model. The results demonstrate that integrating the 3-D model into the FB method improves the accuracy of locating the typhoon-induced P-wave microseism source regions. [ABSTRACT FROM AUTHOR]

The energy-resolved neutron imaging system, RADEN, has been installed at the pulsed neutron source in the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex. In addition to conventional neutron radiography and tomography, RADEN, the world's first imaging beam-line at a pulsed neutron source, provides three main options for new, quantitative neutron imaging techniques: Bragg-edge imaging to visualize the spatial distribution of crystallographic information, resonance absorption imaging for elemental composition and temperature information, and polarized neutron imaging for magnetic field information. This paper describes the results of characterization studies of the neutronic performance and installed devices at RADEN and shows the results of several demonstration studies for pulsed neutron imaging. [ABSTRACT FROM AUTHOR]

The rapid development of wind energy in Japan and the associated high uncertainties and fluctuations in power generation present a big challenge for both wind power generators and electric grids. Accurate and reliable wind power predictions are necessary to optimize the integration of wind power into existing electrical systems. In this study, a hybrid forecasting system of wind power generation was developed by integrating the Kalman filter (KF) with the high resolution Weather Research and Forecasting (WRF) model as well as an empirical formula of wind power output (power curve). The system has been validated with observations including wind speed and power output over a six-month period for 15 turbine sites at a wind farm in Awaji-island, Japan. The results show that the tuned WRF model is able to provide hub-height wind speed prediction for the target area with reliability to some extent. The predicted wind field can be substantially improved by the Kalman filter as a post-processing procedure. The 15-turbine averaged improvements of mean error, root mean square error, and correlation coefficient are 97%, 22%, and 10%, respectively. Meanwhile, the Kalman filter also demonstrates a promising capability of reducing the uncertainties in the power curve model. Systematic validations regarding both wind speed and power output were carried out against the observations for the target wind farm, which show that the hybrid power forecasting system presented in this paper can be an effective and practical tool for short-term predictions of wind speed and power output in Japan area. [ABSTRACT FROM AUTHOR]