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This paper presents a neural network model to estimate wave spectra from wave parameters by the zero-crossing analysis, maximum, significant, and average wave heights and their corresponding wave periods. The present model was trained with the wave data in the JES (Japan/East Sea), and then applied to wave measurements in the Yellow Sea and the South Sea for its feasibility at other seas. According to the present study, the predicted wave spectra well agree with the measurements, even the wave data not in model training. This comparison shows that the accuracy of the present model is comparable to that of JONSWAP wave spectrum. Furthermore, the present model was employed to the wave hindcasting to see its applicability, while JONSWAP wave spectrum also being applied. The significant wave heights from both numerical simulations well agree with the measured ones. However, the average RMSE of significant wave period with the present neural network was 7.08 % smaller than the other, and its Pearson's correlation coefficient is 6.33 % larger on average. From this, it can be seen that the present model was well applied to the wave hindcasting without considering the local wave measurements. • This paper presents a neural network model to estimate wave spectra from wave parameters by the zero-crossing analysis, maximum, significant, and average heights and the corresponding wave periods. • The wave spectra predicted by the present model well agree with the measured ones. The accuracy of present model is comparable to that of JONSWAP wave spectrum with Hwang et al.'s (2021) peak enhancement factor, comparing them. • The present model was employed to the wave hindcasting in Young-il bay to see its applicability. The numerical simulation with incident waves by JONSWAP wave spectrum was also carried out to compare the applicability of both models. • The numerical results show that the significant wave heights from both models are similar to each other. However, the significant wave period with the present model is more accurate than the other. [ABSTRACT FROM AUTHOR]

A rational rheology model is critical for the numerical simulation of debris-flow behavior. The Bingham model commonly used in many current studies has failed to simulate the shear thickening and thinning phenomenon in experiments. We report an alternative solution by incorporating the Herschel-Bulkley-Papanastasiou (HBP) model with the smoothed particle hydrodynamic (SPH) method. The SPH simulation is based on the open-source DualSPHysics scheme, upon which we built a development by the Bingham-based rheology model in our previous study. In this paper, a straightforward improvement is made such that the HBP model is incorporated to describe the constitutive law between particles, extending the compatibility of the simulation to dilatant and pseudoplastic fluids. To illustrate the performance of the HBP-based SPH method, first, a sensitivity analysis was performed to investigate the influence of important rheological coefficients. The proposed method was then verified by a dam-break experiment of water-clay mixtures and the case study of the 2010 Yohutagawa debris-flow event in Japan. The results indicate a good accordance between simulation and observation. A discussion regarding the potential and limitations of the current method concludes the paper. • An HBP-based SPH method is proposed for numerical simulation of debris flows. • Shear thickening and thinning phenomenon of debris-flow mixture can be simulated. • A sensitivity analysis on the HBP rheological model is conducted. • The performance of the proposed method has been verified by experiment and case study. [ABSTRACT FROM AUTHOR]

Abstract: On March 11, 2011, Japan was shaken by the 2011 off the Pacific coast of Tohoku earthquake (the Great East Japan Earthquake). This paper reports some aspects of this earthquake related to long-period ground motions and its impact on building structural design. It was reported that long-period ground motions were induced extensively in Tokyo, Nagoya and Osaka. The response of high-rise buildings to the recorded ground motions during this earthquake and the simulated ground motions provided by the Japanese Government is discussed from the viewpoint of resonance and critical excitation. The main topics of this paper are (i) the investigations on uncertainties in long-period ground motions (uncertainty in predominant frequency, duration and amplitude) and (ii) its impact on structural design of super high-rise buildings. It is shown finally that the earthquake input energy and its bound analysis lead to clearer understanding of the effect of long-period ground motion on building structural design. [Copyright &y& Elsevier]

This paper aims to establish guidelines for public pension reform in Japan, using a numerical simulation approach. The paper introduces the example of a minimum guaranteed pension in the Swedish pension system and compares this with the basic pension in Japan's public pension system, with regard to methods of income redistribution through a public pension scheme. Simulation results show that the switch from the basic pension to the guaranteed pension does not always generate favorable results. If we consider a public pension program with the same scale as the current Japanese program, the highest level of social welfare is attained when a public pension system consists of only a basic pension and is financed by a consumption tax. [ABSTRACT FROM AUTHOR]

Electric vehicles (EV) are treated as a breakthrough technology in the automotive market. The novelty of this technology also implicates that the incidence of these vehicles worldwide is still low. An important issue regarding EVs is the existence of proper charging infrastructure as waiting at charging stations due to an inadequate number of chargers can discourage EV owners. However, as the number of EVs and charging stations are low at present, real world experience is not available, so computer simulations are required for the planning of such charging stations. We developed a stochastic model in this paper that includes driving and charging behaviour of EV owners in Japan. The model is based on Monte Carlo methods and was implemented in MATLAB. We conducted simulations with this model to find out whether the existing infrastructure is adequate for the charging of a large number of EVs. The results indicate that Japan is well prepared for an increase in plug-in vehicles (PHEVs) in the near future: currently the country has 6 fast chargers for 100 electric cars and for this ratio - on average -, waiting probability at DC (direct current) fast chargers ranges lower than 5%, which is an acceptable value for EV owners. If, however, the ratio decreases, waiting probability increases exponentially. [ABSTRACT FROM AUTHOR]

This paper presents empirical formulas for calculating the maximum wave height and period in a numerical wave hindcasting model in terms of significant wave height, mean wave period, and peakedness parameter. The formulas are developed by applying the least-square method to the wave data measured at KOGA-E1 and KOGA-S2, which are located in the Japan/East Sea and on the southeast coast of the Korean Peninsula, respectively. The developed formulas are validated by comparing with the wave measurements around the Korean Peninsula. The formulas are shown to concur well with the measurements even in the Yellow Sea where the tide is very strong. To examine the applicability of the formulas in a wave hindcasting model, numerical simulation has been performed for wind wave generation around the Korean Peninsula. The maximum wave height and period have been calculated using the wave parameters computed in the numerical simulation. The calculated maximum wave height and period are then compared with the measurements to show that the developed formulas can be used for long-term prediction of the maximum wave height and period in a numerical wave hindcasting model. This comparison shows that the predicted maximum wave height and period agree well with the measured ones. Image 10768 • This paper presents formulas on the maximum wave height and period in terms of spectral wave parameters. • The formulas were developed using the wave measurements in the Japan/East Sea and on the southeast of Korean peninsula. • The applicability of the present formulas was examined by the wave hindcasting around the Korean peninsula. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the results of regional scale atmospheric dispersion simulation of accidental emission of radionuclides from the Fukushima Daiichi Reactor, Japan following the Tohoku earthquake and tsunami event on 11 March 2011. The objective was to study the temporal behaviour of plume trajectory, concentration, deposition and radiation dose pattern over an 80 km range around the reactor. The time-varying meteorological parameters during the release period were simulated with a multi-scale nested atmospheric model WRF ARW and the trajectory, plume dispersion were computed with Lagrangian Particle Dispersion models HYSPLIT, FLEXPART using the available information on accidental source term. The simulations indicated that the wind flow over Japan during the release period was driven by the large scale extra-tropical westerly waves and associated low pressure systems. In the lower levels, the flow was influenced by the local topography/sea breeze causing occasional landward wind shift on the east coast of Japan. Simulated airflow trajectories revealed that the plume stayed over the ocean by westerly winds on most days and the radioactivity dispersed over sea surface. Landward trajectories were found on a few days due to southeasterly, easterly and northeasterly flow (15–17, 19–21 March 2011) during which much of the radionuclides deposited over the land region. The hotspot of depositions occurred over east Pacific Ocean near to Japan. Over the land relatively high depositions were simulated in a narrow zone of 20 km width and 80 km length in the northwest sector in agreement with monitor data. Simulations showed wet depositions over the land to be higher than the dry depositions during 12–30 March due to occurrence of rainfall on some days. Comparison of activity deposition and air dose values with available observations confirmed that the plume pattern in a finer length scale around the site could be simulated realistically and agree with the measurements within the limitations of the uncertainty in source term. [Copyright &y& Elsevier]