Near-Infrared Colors of the Binary Kuiper Belt Object 1998 WW 31

We have measured near-infrared colorsof the binary Kuiper Belt object (KBO)1998 WW₃₁ using the Subaru Telescope withadaptive optics. The satellite was detectednear its perigee and apogee(0.18“ and 1.2” apart from the primary).The primary and the satellite have similar H–Kcolors, while the satellite is redder thanthe primary in J–H. Combined with the Rband magnitude previously published byVeillet et al., 2002, the color of the primaryis consistent with that of optically red KBOs. Thesatellite's R-, J-, H-colors suggest thepresence of ～1 μm absorption band dueto rock-forming minerals. If the surface of thesatellite is mainly composed by olivine, thesatellite's albedo is higher value than the canonicallyassumed value of 4%.     

Active impulsive echo discrimination in shallow water by mappingtarget physics-derived features to classifiers

One of the most difficult challenges in shallow-water active sonar processing is false-alarm rate reduction via active classification. In impulsive-echo-range processing, an additional challenge is dealing with stochastic impulsive source variability. The goal of active classification is to remove as much clutter as possible while maintaining an acceptable detection performance. Clutter in this context refers to any non-target, threshold-crossing cluster event. In this paper, we present a clutter-reduction algorithm using an integrated pattern-recognition paradigm that spans a wide spectrum of signal and image processing-target physics, exploration of projection spaces, feature optimization, and mapping the decision architecture to the underlying good-feature distribution. This approach is analogous to a classify-before-detect strategy that utilizes multiple informations to arrive at the detection decision. After a thorough algorithm evaluation with real active sonar data, we achieved over an order of magnitude performance improvement in clutter reduction with our methodology over that of the baseline processing     

An approach for evaluating the hydrological effects of urbanization and its application

This study focuses mainly on observing urban development in Taiwan's Wu‐Tu watershed from the perspective of urban hydrological theory. An approach is proposed for developing a method for incorporating available meteorological data to define the degree of change in a runoff hydrograph for urbanizing basins. The mean rainfall was estimated using the Kriging method. For calibration, two methods of calculating the effective rainfall (the Φ‐index method and the non‐linear‐programming (NLP) method) were used as model inputs, and the optimal global parameters of the linear reservoir model were then obtained from the shuffled complex evolution (SCE) algorithm. Twenty‐six (1966–1991) and eight (1994–1997) rainfall–runoff events were used for calibration and verification, respectively. The NLP method yielded better results than the Φ‐index method, especially for multipeak rainfall–runoff events. The regression equation determined the relationship between the parameters of the model and impervious areas. A comparison based on the results of the instantaneous unit hydrograph of the study area revealed that three decades of urbanization had increased the peak flow by 27%, and the time to peak was decreased by 4 h. The study simply describes the results of the impact of imperviousness on hydrological modelling. Copyright © 2002 John Wiley & Sons, Ltd.     

基于钻孔截面变形方法(CBDM)测量岩石应力变化

本文发展了一种基于钻孔技术来监测岩石应力变化的钻孔截面变形法(CB-DM),该方法可以用来测量垂直于钻孔轴线的岩体的二维应力状态变化.本文通过载有激光位移传感器的样机,对该方法进行详细介绍,理论上分析测量结果的影响因子,证明该方法能够有效估测岩体的应力变化.     

A new prototype system for earthquake early warning in Taiwan

A new prototype earthquake early warning (EEW) system is being developed and tested using a real-time seismographic network currently in operation in Taiwan. This system is based on the Earthworm environment which carries out integrated analysis of real-time broadband, strong-motion and short-period signals. The peak amplitude of displacement in the three seconds after the P arrival, dubbed P_d, is used for the magnitude determination. Incoming signals are processed in real time. When a large earthquake occurs, P-wave arrival times and P_d will be estimated for location and magnitude determinations for EEW purpose. In a test of 54 felt earthquakes, this system can report earthquake information in 18.8±4.1 s after the earthquake occurrence with an average difference in epicenter locations of 6.3±5.7 km, and an average difference in depths of 7.9±6.6 km from catalogues. The magnitudes approach a 1:1 relationship to the reported magnitudes with a standard deviation of 0.51. Therefore, this system can provide early warning before the arrival of S-wave for metropolitan areas located 70 km away from the epicenter. This new system is still under development and being improved, with the hope of replacing the current operational EEW system in the future.     

Phantom without ghost

The Nine-Year WMAP results combined with other cosmological data seem to indicate an enhanced favor for the phantom regime, comparing to previous analyses. This behavior, unless reversed by future observational data, suggests to consider the phantom regime more thoroughly. In this work we provide three modified gravitational scenarios in which we obtain the phantom realization without the appearance of ghosts degrees of freedom, which plague the naive approaches on the subject, namely the Brans-Dicke type gravity, the scalar-Einstein-Gauss-Bonnet gravity, and the F(R) gravity, which are moreover free of perturbative instabilities. The phantom regime seems to favor the gravitational modification instead of the universe-content alteration.     

Reproducibility of spatial and temporal distribution of aseismic slips in Hyuga-nada of southwest Japan

The Hyuga-nada region of southwest Japan, which is located off the east coast of Kyushu Island, may have the potential to generate great interplate earthquakes along the Nankai trough in the future. In this area, thrust earthquakes of M = 6.7–7.2 have occurred with recurrence intervals of approximately 30 years. In association with these earthquakes, possible local heterogeneities of plate coupling may be expected within 100 km from the coast in the Hyuga-nada region. We investigate numerical experiments to determine the spatial and temporal resolution of slip on the plate interface beneath the Hyuga-nada offshore region. For this purpose, we calculated synthetic displacement data from the result of numerical simulation conducted for the afterslip following an M_w 6.8 earthquake, for existing global positioning system stations on land and planned ocean floor seismic network stations. The spatial and temporal distribution of fault slip is then estimated using a Kalman filter-based inversion. The slip distribution estimated by using ocean floor stations demonstrates that the heterogeneity of plate coupling is resolved approximately within 50 km from the coastal area. This heterogeneity corresponds to the coseismic area of an M_w 6.8 earthquake with a radius of 10 km. Our study quantitatively evaluates the spatial resolution of aseismic slip in the Hyuga-nada region. Analysis based on continuous ocean floor data is useful for resolving the spatial variations of heterogeneities in plate couplings.     

Improvement of earthquake locations with the Marine Cable Hosted Observatory (MACHO) offshore NE Taiwan

In order to improve the locating capability for offshore earthquakes and tsunamis monitored off northeastern Taiwan, a cable-based ocean bottom seismographic observatory named “Marine Cable Hosted Observatory” (MACHO) was constructed and began operation at the end of 2011. The installed instruments of the observatory include a broadband seismometer, a strong-motion seismometer and a pressure gauge. In addition, various scientific instruments could be deployed for other purposes as well. At present, the seismic data are transmitted in real-time via a fiber cable, and integrated into the current inland seismographic network in Taiwan. The ocean bottom station has contributed to provide high quality seismic data already. According to observations from January 2012 to June 2013, there were a total of 15,168 earthquakes recorded by the system. By using the data from the ocean bottom station, the number of relocated earthquakes with an azimuth gap less than 180 degrees substantially increase about 34 %. Meanwhile, the root–mean–square of the time residual, the error in epicenter, and the error in depth of the earthquake locations decrease. Therefore, the implementation of MACHO has the advantage of extending the coverage of existing the Taiwan seismic network to the offshore, providing more accurate and real-time seismic data for offshore earthquakes monitoring. The results show that MACHO is crucial and necessary for monitoring seismic activities in northeastern Taiwan.     

Variation of the southern Subtropical Countercurrent related to sea surface height and eddies in the northwest tropical pacific

The ADCP records obtained at about 18°N, 135°E show the southern branch of the Subtropical Countercurrent (STCC). The sea surface heights (SSH) show that there is a tendency to increase and decrease in the south/north of STCC, respectively. So the variability of SSH ultimately contributes to the strengthening of STCC through geostrophic balance. The southern STCC branch distinctly persists from winter to spring. Since 2005, the southern STCC exists almost throughout the year, and the STCC is clearly stronger to the east of 145°E. Anticyclonic and cyclonic eddies exist seemingly as bands around 17.5°N and 20.5°N, respectively. The STCC flowing eastward, which is formed by the geostrophic balance, is maintained with the interaction between geostrophic currents and anticyclonic-cyclonic eddies. The rotating eddies exert an additional driving force to maintain the eastward flow of STCC, and then the STCC reveals a meandering movement due to the interaction with the eddies. The trajectories of surface drifters together with the altimeter data analysis in June 2009 dictate the variability of the STCC induced by the interaction between eddies and the eastward flow. These results suggest that the southern STCC slowly changes from an intra-seasonal event an annual one with time duration of over 21 months.     

Analytical and experimental studies on midstory isolated buildings with modal coupling effect

In a midstory isolated building, the isolation system is incorporated into the midstory rather than the base of the building. Because of the flexibility of the substructure below the isolation system in a midstory isolated building, the contribution of higher modes to the seismic responses of the midstory isolated structure may not be negligible, especially when the coupling of higher modes exists. To investigate this modal coupling effect, a simplified three‐lumped‐mass structural model of the midstory isolated building is assumed in this study. Through the equivalent linear analysis and shaking table tests, it is found that the coupling of higher modes may lead to enlarged acceleration responses at the super‐floor and superstructure above the isolation layer. Accordingly, a simple method to prevent the midstory isolation design from the coupling of higher modes attributed to the improper design of the substructure and superstructure is proposed in this paper. Copyright © 2012 John Wiley & Sons, Ltd.