Two-dimensional continuous wavelet transform of simulated spatial images of waves on a slowly varying topography

The wavelet transform (WT) is now recognized as a useful, flexible, and efficient technique to analyze intermittent, non-stationary and inhomogeneous signals as well as images which are obtained from experimental or in situ measurements. In this study, the two-dimensional continuous wavelet transform (2-D CWT) was introduced to analyze the spatial image of waves. The numerical algorithm of 2-D CWT was developed and testified in simulated wave field of regular and random waves. Some more simulated wave fields of various wave conditions and sea bed slopes were then assumed to verify the analytical accuracy of this new technique. The comparisons of estimations to theoretical values for several wave parameters show that the 2-D CWT is capable of identifying the directional spectra and wave properties in shallow water.     

Design and implementation of an adaptive code discriminator in a DSP/FPGA-based Galileo receiver

In the design of a global navigation satellite system receiver, the tracking performance depends on the code tracking loop and the associated discriminator. An adaptive code discriminator under a multi-correlator architecture has been designed based on a multi-objective principle to achieve a balance among various, sometimes conflicting, design objectives. With the proposed optimization approach and adaptive logic, concerns of large pull-in region and small steady-state error can be addressed. The proposed scheme is implemented in a digital signal processor/field programmable gate array board and an experiment is conducted to process GIOVE-A signals. The test results reveal the advantages of the proposed code tracking architecture and discriminator design.     

Impact of Direct Radiative Forcing of Anthropogenic Aerosols on Diurnal Temperature Range in January in Eastern China

This study investigates the changes in January diurnal temperature range(DTR) in China during 1961-2000.The observed DTR changes during 1981-2000 relative to 1961-80 are first analyzed based on the daily temperature data at 546 weather stations.These observed DTR changes are classified into six cases depending on the changes in daily maximum and minimum temperatures,and then the occurrence frequency and magnitude of DTR change in each case are presented.Three transient simulations are then performed to understand the impact of greenhouse gases(GHGs) and aerosol direct forcing on DTR change:one without anthropogenic radiative forcing,one with anthropogenic GHGs,and another one with the combined forcing of GHGs and five species of anthropogenic aerosols.The predicted daily DTR changes during the years 1981-2000 are also classified into six cases and are compared with the observations.Results show that the previously proposed reason for DTR reduction,a stronger nocturnal warming than a daytime warming,explains only 19.8%of the observed DTR reduction days.DTR reductions are found to generally occur in northeastern China,coinciding with significant regional warming.The simulation with GHG forcing alone reproduces this type of DTR reduction with an occurrence frequency of 32.9%,which is larger than the observed value.Aerosol direct forcing reduces DTR mainly by daytime cooling.Consideration of aerosol cooling improves the simulation of occurrence frequencies of different types of DTR changes as compared to the simulation with GHGs alone,but it cannot improve the prediction of the magnitude of DTR changes.     

Spatial and temporal variations in rainfall characteristics in mountainous and lowland areas in Taiwan

Although changes in rainfall characteristics have been noted across the world, few studies have reported those in mountainous areas. This study was undertaken to clarify spatial and temporal variations in rainfall characteristics such as annual rainfall amount (Pr), mean daily rainfall intensity (η), and ratio of rain days (λ) in mountainous and lowland areas in Taiwan. To this aim, we examined spatial and year‐to‐year variations and marginal long‐term trends in Pr, η, and λ, based on rainfall data from 120 stations during the period 1978–2008. The period mean rainfall () at the lowland stations had strong relationships with the period mean daily rainfall intensity () and the period mean ratio of rain days () during those 31 years. Meanwhile, was only strongly related to at mountainous stations, indicating that influences on spatial variations in were different between lowland and mountainous stations. Year‐to‐year variations in Pr at each station were primarily determined from the variation in η at most stations for both lowland and mountainous stations. Long‐term trend analysis showed that Pr and η increased significantly at 10% and 31% of the total 120 stations, respectively, and λ decreased significantly at 6% of the total. The increases in Pr were mostly accompanied by increases in η. Although stations with significant η increases were slightly biased toward the western lowland area, increases or decreases in Pr and λ were not common. These results contribute to understanding the impacts of possible climate changes on terrestrial hydrological cycles. Copyright © 2012 John Wiley & Sons, Ltd.     

Generation of Power by Microbial Fuel Cell with Ferricyanide in Biodegradation of Benzene

The power generation potential of a microbial fuel cell (MFC) during the process of benzene biodegradation with potassium ferricyanide (0–200 mM) as the terminal electron acceptor was evaluated. Experimental results demonstrate that benzene was used as the sole carbon source in generating electricity by a mixed culture. The power density increased from 0.0276 to 2.1 mW m^?2 as the concentration of potassium ferricyanide in the cathode chamber was increased from 0 to 200 mM. With a benzene concentration of 10.87 mg L^?1 and a potassium ferricyanide concentration of between 0 and 150 mM, complete degradation of benzene was achieved in 22–24.5 h. However, when the concentration of potassium ferricyanide was raised to 200 mM, the time required for complete benzene degradation was prolonged to 35 h. The results of this investigation can be used as a basis for future assessments of the power generation capacity of MFCs that are used to treat benzene‐contaminated wastewater.     

Locating, monitoring, and characterizing typhoon-linduced landslides with real-time seismic signals

Landslides induced by typhoon Morakot during its passage across Taiwan on 7–9 Aug 2009 claimed more than 700 lives and caused heavy economic loss. Unlike earthquake monitoring, precise locations of landslides could not be determined in near-real time because their seismic phases are difficult to identify. Here, we show that large, damaging landslide events are characterized seismically by a distinct waveform pattern of frequent intermixes of P and S waves over a time window of several tens of seconds. The predominant frequency band during these time windows ranges from 0.5 to 5?Hz. The high-frequency content is clearly deficient relative to that of local earthquakes by about one to two orders. We also demonstrate that large landslide events can be located and monitored with algorithms specifically designed for real-time seismic applications. This near-real-time monitoring capability would be particularly useful for emergency responders and government organizations to coordinate effective relief-and-rescue operations.     

GIS-based evaluation on the fault motion-induced coseismic landslides

Earthquake-induced potential landslides are commonly estimated using landslide susceptibility maps. Nevertheless, the fault location is not identified and the ground motion caused by it is unavailable in the map. Thus, potential coseismic landslides for a specific fault motion-induced earthquake could not be predicted using the map. It is meaningful to incorporate the fault location and ground motion characteristics into the landslide predication model. A new method for a specific fault motion-induced coseismic landslide prediction model using GIS (Geographic Information System) is proposed herein. Location of mountain ridges, slope gradients over 45 o , PVGA (Peak Vertical Ground Accelerations) exceeded 0.15 g, and PHGA (Peak Horizontal Ground Accelerations) exceeded 0.25 g of slope units were representing locations that initiated landslides during the 1999 Chi-Chi earthquake in Taiwan. These coseismic landslide characteristics were used to identify areas where landslides occurred during Meishan fault motion-induced strong ground motions in Chiayi County in Taiwan. The strong ground motion (over 8 Gal in the database, 1 Gal = 0.01 m/s 2 , and 1 g = 981 Gal) characteristics were evaluated by the fault length, site distance to the fault, and topography, and their attenuation relations are presented in GIS. The results of the analysis show that coseismic landslide areas could be identified promptly using GIS. The earthquake intensity and focus depth have visible effects on ground motion. The shallower the focus depth, the larger the magnitude increase of the landslides. The GIS-based landslide predication method is valuable combining the geomorphic characteristics and ground motion attenuation relationships for a potential region landslide hazard assessment and in disaster mitigation planning.     

Yangtze- and Taiwan-derived sediments on the inner shelf of East China Sea

X-ray diffraction (XRD) mineralogical and grain-size analyses indicate that inner continental shelf sediments in the East China Sea (ECS) represent a unique mixing of clays derived from the Yangtze River and silts/sands from small western Taiwanese rivers. Taiwanese (e.g., Choshui) clays (<2 μm) display no smectite but the best illite crystallinity and are only distributed along southeastern Taiwan Strait. Both Yangtze and Taiwanese river clays are illite-dominated, but the poor illite crystallinity and the presence of smectite and kaolinite indicate that Taiwan Strait clays are mainly Yangtze-dominated. In contrast, medium silts (20–35 μm) and very fine sands (63–90 μm) in the Taiwan Strait are characterized by low feldspar/quartz, low K-feldspar/plagioclase and high kaolinite/quartz, indicating their provenance from Taiwanese rivers. Taiwanese silts and sands are introduced primarily by the way of typhoon-derived floods and transported northward by the Taiwan Warm Current during summer–fall months. Yangtze clays, in contrast, are widely dispersed southward about 1000 km to the western Taiwan Strait, transported by the China Coastal Current during winter–spring months. Since most Taiwan Strait samples were collected in May 2006, clay results in this paper might only represent the winter–spring pattern of the dispersal of Yangtze sediments.     

Weighted discriminators for GNSS BOC signal tracking

Modern Global Navigation Satellite System including Galileo and GPS III will employ multiplexed binary offset carrier (MBOC) modulation to achieve spectrum separation and enhanced tracking performance. A challenge of the MBOC or BOC signal tracking is the presence of ambiguities due to multiple sidepeaks of the autocorrelation functions. Several different techniques including multi-correlator and double estimator schemes have been proposed to address the ambiguity issue. We propose a class of ambiguity-free code tracking techniques by exploiting the unique features of the BOC modulation. In the proposed architecture, the incoming BOC-modulated signals are correlated with BOC-modulated replica and the spreading codes, respectively. Through a multiplicative combination strategy of the two correlator outputs, a noncoherent weighted discriminator is formed and shown to possess the ambiguity-free property. The multipath effect is assessed and compared with existing early-minus-late power and autocorrelation sidepeak cancellation technique discriminators. The noise effects of the theory and simulation are also discussed. In order to further verify the proposed scheme, a set of field data of a Galileo in-orbit validation satellite is collected and processed. It is demonstrated that the proposed method is simple to implement, free from ambiguities, and yields acceptable performance in the presence of multipath and noise.