Impact of the 2011 tsunami on the littoral system around offshore breakwaters on Sendai Coast

After the 2011 Great East Japan Earthquake Tsunami, littoral system on Sendai Coast have been changing due to tsunami-induced highly non-equilibrium condition along the coast. In order to clarify the modification of littoral environment and its subsequent recovery on Sendai Coast, analysis of shoreline change has been carried out. In this study, the shoreline was extracted from frequently captured aerial photographs from 2009 until now, and analysis using an empirical orthogonal function (EOF) method was conducted. It is seen that the shoreline retreated greatly due to tsunami event. In particular, tombolo which existed behind the offshore breakwater completely disappeared due to the tsunami. Total of contribution of the 1st and 2nd EOF components is more than 70%. It is concluded that the 1st component originated from cross-shore sediment movement, while the 2nd component represents longshore sediment transport. Although the 1st component shows only slight modification after the tsunami, the 2nd component resulting from a longshore sediment transport shows distinct change after the tsunami around the offshore breakwaters

Neurophysiological modeling of bladder afferent activity in the rat overactive bladder model

The overactive bladder (OAB) is a syndrome-based urinary dysfunction characterized by “urgency, with or without urge incontinence, usually with frequency and nocturia”. Earlier we developed a mathematical model of bladder nerve activity during voiding in anesthetized rats and found that the nerve activity in the relaxation phase of voiding contractions was all afferent. In the present study, we applied this mathematical model to an acetic acid (AA) rat model of bladder overactivity to study the sensitivity of afferent fibers in intact nerves to bladder pressure and volume changes. The afferent activity in the filling phase and the slope, i.e., the sensitivity of the afferent fibers to pressure changes in the post-void relaxation phase, were found to be significantly higher in AA than in saline measurements, while the offset (nerve activity at pressure ~0) and maximum pressure were comparable. We have thus shown, for the first time, that the sensitivity of afferent fibers in the OAB can be studied without cutting nerves or preparation of single fibers. We conclude that bladder overactivity induced by AA in rats is neurogenic in origin and is caused by increased sensitivity of afferent sensors in the bladder wall

Seasonal variation of morphology and sediment movement on Nha Trang Coast, Vietnam

The Nha Trang beach, an embayed sandy beach located in the southeast of Vietnam, is a tropical touristic coastal environment that is being threat by persistent shoreline retreat. In order to investigate the processes underlying this erosive pattern, 1.5-years of video imagery, obtained from a local video system, was analyzed. Video products such as shoreline position and surf zone width (extracted from time-averaged images) were used to identify patterns of shoreline variability (using empirical orthogonal function - EOF) and investigate the link between the seasonal variations in the wave forcing and longshore sediment transport. Results indicate that shoreline retreat occurs essentially during the winter season, when energetic northeast monsoon waves dominate. The recovery phase (shoreline advance) was found to occur during the summer season, when milder south/southeast wind waves dominate. Shoreline variability was further investigated using EOF analysis and results show that the first mode, which explains 89% of the observed variance, corresponds to the seasonal longshore shoreline variations. This EOF mode was found to strongly related to the winter and summer monsoon seasons, thus reinforcing the role that seasonal changes in the wave climate play on the shoreline variations. Finally, the net of longshore sediment transport in Nha Trang beach was investigated using seasonal and monthly depth of closure (D-c) information, rather than a single fixed value of this parameter. The results highlight that the use of monthly or seasonal D-c values allow to capture the seasonal variations in the wave climate, thus providing more realistic patterns of sediment transport in this coastal area

Performance Evaluation Of Biped Robot Optimal Gait Based On Genetic Algorithm

A Genetic Algorithm (GA) gait synthesis method for walking biped robots is considered in this paper. The walking occupy most of the time during the task performance, therefore its gait is analyzed based on the minimum consumed energy (CE) and minimum torque change (TC). The biped robot optimal gait is considered starting from static standing state and continuing with normal walking. The proposed method can be applied for wide ranges of step lengths and step times and for other tasks that might to be performed by humanoid robot. By using GA as an optimization tool it is easy to include constraints and add new variables to be optimized. The biped robot gait is generated without neglecting the stability, which is verified by the zero moment point ZMP concept. Simulations are realized based on the parameters of "Bonten-Maru I" humanoid robot. The evaluation by simulations shows that the proposed method has a good performance and energy is significantly reduced