Theoretical Estimation of the Acoustic Energy Generation and Absorption Caused by Jet Oscillation

We investigate the energy transfer between the fluid field and acoustic field caused by a jet driven by an acoustic particle velocity field across it, which is the key to understanding the aerodynamic sound generation of flue instruments, such as the recorder, flute, and organ pipe. Howe’s energy corollary allows us to estimate the energy transfer between these two fields. For simplicity, we consider the situation such that a free jet is driven by a uniform acoustic particle velocity field across it. We improve the semi-empirical model of the oscillating jet, i.e., exponentially growing jet model, which has been studied in the field of musical acoustics, and introduce a polynomially growing jet model so as to apply Howe’s formula to it. It is found that the relative phase between the acoustic oscillation and jet oscillation, which changes with the distance from the flue exit, determines the quantity of the energy transfer between the two fields. The acoustic energy is mainly generated in the downstream area, but it is consumed in the upstream area near the flue exit in driving the jet. This theoretical examination well explains the numerical calculation of Howe’s formula for the two-dimensional flue instrument model in our previous work [Fluid Dyn. Res. 46, 061411 (2014) ] as well as the experimental result of Yoshikawa et al. [ J. Sound Vib. 331, 2558 (2012) ]

Development of a 4.2 V aqueous hybrid electrochemical capacitor based on MnO2 positive and protected Li negative electrodes

An aqueous hybrid electrochemical capacitor consisting of a capacitive manganese oxide (MnO2) positive electrode and a water-stable, protected Li negative electrode in near-neutral aqueous electrolyte (1.0 M Li2SO4, pH = 5.5) is demonstrated. Galvanostatic charge/discharge cycling tests were conducted with pouched cells, offering a cell voltage of 4.2 V with maximum specific energy of 753 W h kg(-1) based on the positive electrode. The combination of a pseudocapacitive MnO2 positive and a Li negative electrode offers high specific charge and cell voltage, resulting in an aqueous hybrid electrochemical capacitor having exceptionally high specific energy.ArticleJOURNAL OF POWER SOURCES. 241:572-577 (2013)journal articl

Surface air temperature response to increasing anthropogenic aerosols in Asian monsoon region in boreal winter

This study investigated the surface air temperature (SAT) response to increasing anthropogenic aerosol (AA) by separating it into fast and slow responses using the Coupled Model Intercomparison Project Phase 6 climate model outputs. Although an increase in AA generally contributes to cooling SAT over and around the source regions, this study focused on some notable responses, particularly unexpected warming signals over South Asia. In boreal winter, the slow response of SAT contributed to the relative warming over and around India, whereas the fast response did not. As the slow response, a decrease in cloud fraction, enhancement of downward anomalous motion, and an increase in downward radiation flux anomaly at the surface were found, which corresponded to the relative warming, although none of these occurred as fast response. These results suggest that processes mediated by sea surface temperature and clouds are critical for the relative warming over South Asia in boreal winter

Regional contributions through athletic lessons for elementary school children

We have provided athletic lessons for elementary school children for four years. These lessons are at the center of a project that aims to contribute to the local community. Initially, we decided on the following theme: “Have fun, learn to run fast, and stand on the Big Swan track.” To improve children’s competitive abilities, we focused on engaging them in fun activities that would lay the foundation for a life filled with sports; to motivate and engage the children, we gave them a chance to attend track meets as part of the program. This project has great potential, both as a practical approach to Track and Field instruction and as a basis for student volunteer activities in the elementary school teaching course. We believe that faculty members and students of Niigata University of Health and Welfare will be able to connect with many more children in the region through this project

HIP KINEMATICS AND MUSCLE ACTIVITY DURING INSIDE SOCCER KICK IN PLAYERS WITH A HISTORY OF GROIN PAIN

The purpose of this study was to clarify the kinematic characteristics of groin pain (GP). In addition, we investigated the correlations between the kinematics of inside soccer kick movement and muscle activities in the lower extremities. Twenty-four male soccer players (control group, 13; GP group, I1 ) were instructed to perform maximum inside kick. Our results showed that the adductor muscle activity was maintained from the back swing to the leg acceleration phase in the in GP group but was decreased from the peak value at the back swing to the leg acceleration phase in the control group. In the leg acceleration phase, the adductor muscle activity was significantly higher in the GP group than in the control group. The GP group showed faster adduction/abduction velocity of the kicking leg in all kicking phases than the control group