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

Jyh-Ching Juang  Yu-Hsuan Chen  Tsai-Ling Kao  Yung-Fu Tsai 《GPS Solutions》2010,14(3):255-266

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.  相似文献   

A self-contained GIM-aided Abel retrieval method to improve GNSS-Radio Occultation retrieved electron density profiles     

Tulasi Ram  S.  Su  Shin-Yi  Tsai  Lung-Chi  Liu  Chao Han 《GPS Solutions》2016,20(4):825-836

GPS Solutions - A self-contained global ionospheric maps (GIM)-aided Abel retrieval method is adopted that can account for spherical non-uniformity along the radio wave path in the vicinity of the...  相似文献   

Ultraviolet spectroscopic evidence for polynuclear lead (II) complexes in synthetic Red Sea brines     

P. Tsai  R.P. Cooney 《Chemical Geology》1976,18(3):187-202

The Pb complexes in a synthetic brine solution with a composition comparable to that of the Atlantis II Deep 56°C Brine have been identified by UV absorption spectroscopy. The important species at ambient temperatures are PbCl^2?₄ and Pb(OH)BrCl₂^2?. At 56°C the former complex partially dissociates to form lower chloro complexes while the latter undergoes halide exchange reactions forming Pb(OH)Br₂Cl^2?. Evidence has also been found for the following polymeric lead hydroxo complexes: Pb₄(OH)₄Cl₄, Pb₆(OH)₃Cl₁₂ and Pb₃(OH)₁₂Cl₄. The predominant polynuclear complex in the brine, Pb₄(OH)₄Cl₄, tends to dissociate at 56°C to form lower polymeric species. The formulation of the limiting binary chloro complex as PbCl₄^2? rather than PbCl₆^4? is supported by the reflectance spectrum of Cs₄PbCl₆.  相似文献   

Estimating the regional climate responses over river basins to changes in tropical sea surface temperature patterns     

Chii-Yun Tsai  Chris E. Forest  Thorsten Wagener 《Climate Dynamics》2015,45(7-8):1965-1982

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Investigation of the impacts of vegetation distribution and evaporative cooling on synthetic urban daytime climate using a coupled LES—LSM model     

Hsin‐Yuan Huang  Steven A. Margulis  Chia Ren Chu  Hsiao‐Chung Tsai 《水文研究》2011,25(10):1574-1586

Local flow properties and regional weather or climate are strongly affected by land‐atmosphere interactions of momentum and scalars within the daytime convective boundary layer (CBL). In this study, we investigate the impact of green space scale on the daytime atmospheric boundary layer (ABL) over a synthetic urban domain using a recently developed large‐eddy simulation‐land surface model (LES–LSM) framework. With the use of realistic soundings as initial conditions, a series of numerical experiments over synthetic urban surfaces with varied scale of vegetated area is performed. Simulated micrometeorological properties, surface fluxes, basic CBL characteristics, and cloud distribution are analysed. The results show reference‐level air potential temperature and specific humidity as well as surface fluxes over green space are significantly affected by the scale of green space in the urban domain. The surface organization due to vegetated area scale also has impacts on horizontally averaged scalar and momentum profiles; however, the magnitude in this study is smaller than the results of a previous study using a set of offline surface fluxes as the lower boundary condition for LES. In addition, even though this study only performs a daytime diurnal cycle, the impact of green space scale on cloud distribution in simulations is significant. The cases with more organized green space yield lower‐elevated cumulus cloud and larger‐cloud cover fraction, which impacts the energy budget at the top of boundary layer and, in turn, could lead to additional surface cooling with respect to longer‐term weather and climate. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Wellbore flow‐rate solution for a constant‐head test in two‐zone finite confined aquifers     

Chi‐Shan Tsai  Hund‐Der Yeh 《水文研究》2012,26(21):3216-3224

The solution describing the wellbore flow rate in a constant‐head test integrated with an optimization approach is commonly used to analyze observed wellbore flow‐rate data for estimating the hydrogeological parameters of low‐permeability aquifers. To our knowledge, the wellbore flow‐rate solution for the constant‐head test in a two‐zone finite‐extent confined aquifer has never been reported so far in the literature. This article is first to develop a mathematical model for describing the head distribution in the two‐zone aquifer. The Laplace domain solutions for the head distributions and wellbore flow rate in a two‐zone finite confined aquifer are derived using the Laplace transform, and their corresponding time domain solutions are then obtained using the Bromwich integral method and residue theorem. These new solutions are expressed in terms of an infinite series with Bessel functions and not straightforward to calculate numerically. A large‐time solution for the wellbore flow rate is therefore developed by employing the relationship of small Laplace variable versus large time variable and L'Hospital's rule. The result shows that the large‐time solution is identical to the steady‐state solution obtained after applying the Tauberian theorem into the Laplace domain solution. This large‐time solution can reduce to the Thiem equation in the case of no skin. Finally, the newly developed solution is used to investigate the effects of outer boundary distance and conductivity ratio on the wellbore flow rate. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Microbial dynamics in an oligotrophic bay of the western subtropical Pacific: Impact of short-term heavy freshwater runoff and upwelling     

An-Yi Tsai  Gwo-Ching Gong  Robert W. Sanders  Chien-Fu Chao  Kuo-Ping Chiang 《Journal of Oceanography》2010,66(6):873-883

This two-year study investigates the possible factors that determine spatial and temporal dynamics of picoplankton (heterotrophic bacteria, autotrophic picoplankton—Synechococcus spp., Prochlorococcus, and picoeukaryotes) and nanoflagellate abundance in the subtropical Ilan Bay, Taiwan, where the inner bay is affected by freshwater run-off from the Lanyang River and the eastern outer bay by the Kuroshio Current. In the inner bay, there was more rain and freshwater discharge in 2005 than in 2004 during the warm season (>24° C, June–September). The abundance of bacteria, Synechococcus spp., Prochlorococcus, and picoeukaryotes and the percentage contributions of pigmented nanoflagellate (PNF %) were two- to eight-fold greater during this period (July in 2005) than for other sampling periods. Relatively low abundance of heterotrophic nanoflagellates (HNF) in the presence of abundant picoplankton prey suggests that top-down control determined HNF abundance in the Ilan Bay, Taiwan.  相似文献   

Influences of soil water characteristic curve on rainfall-induced shallow landslides   总被引：3，自引：2，他引：1  

Tung-Lin Tsai 《Environmental Earth Sciences》2011,64(2):449-459

The analysis of slope instability induced by rainfall was usually performed using the main drying curve as the measurement of the main wetting curve is a more time-consuming and costly task. In this study, the influences of the main drying and wetting curves on rainfall-induced shallow landslides are examined. Three designed scenarios and a real case scenario are used to conduct this examination. The prediction of shallow landslide occurrence is related to the main drying and wetting curves due to the strong relation between groundwater pressure head and hysteresis effect. The main wetting curve may have a less minimum landslide-triggering rainfall amount and a less rainfall duration threshold for landslide occurrence than the drying wetting curve. For safety’s sake, an underestimation of shallow landslide occurrence may be produced by the commonly used main drying curve. In addition, besides the shallow landslide occurrence, the failure depth and the time to failure are also influenced by the main drying and wetting curves. The hysteresis effect should be taken into account for assessing rainfall-induced shallow landslides.  相似文献   

Examination of influences of rainfall patterns on shallow landslides due to dissipation of matric suction   总被引：5，自引：4，他引：1  

Tung-Lin Tsai  Jyun-Kai Wang 《Environmental Earth Sciences》2011,63(1):65-75

The influences of rainfall patterns on shallow landslides due to the dissipation of matric suction are examined in this study. Four representative rainfall patterns including the uniform, advanced, intermediated, and delayed rainfalls are adopted. The results show that not only the occurrence of shallow landslides but also the failure depth and the time of failure are affected by the rainfall pattern. The different rainfall patterns seem to have the same minimum landslide-triggering rainfall amount. There is a rainfall duration threshold for landslide occurrence for a rainfall event with larger than the minimum landslide-triggering rainfall amount. For each rainfall pattern, the rainfall duration threshold for landslide occurrence decreases to constant with the increase of rainfall amount. The uniform rainfall has the least rainfall duration threshold for landslide occurrence, followed by the advanced rainfall, and then the intermediated rainfall. For each rainfall pattern, the failure depths and the times of failure from the same amount of rainfall with different durations could be largely different. In addition, the differences of the failure depths and the times of failure between various rainfall patterns with the same amount and duration of rainfall could be also significant. The failure depth and the time of failure, as compared with the occurrence of shallow landslides, are more sensitive to the rainfall condition. In other words, in comparison with the evaluation of the occurrence of shallow landslides, it needs more accurate rainfall prediction to achieve reliable estimations of the failure depth and the time of failure.  相似文献   

Ten guiding principles for the delineation of priority habitat for endangered small cetaceans     

Peter S. Ross  Jay Barlow  Thomas A. Jefferson  Brendan E. Hickie  Tatiana Lee  Christina MacFarquhar  E. Christien Parsons  Kimberly N. Riehl  Naomi A. Rose  Elisabeth Slooten  Chia-Yang Tsai  John Y. Wang  Andrew J. Wright  Shih Chu Yang 《Marine Policy》2011

The adoption of endangered species laws in various nations has intensified efforts to better understand, and protect, at-risk species or populations, and their habitats. In many countries, delineating a portion of a species' habitat as particularly worthy of protection has become a mantra of these laws. Unfortunately, the laws themselves often provide scientists and managers with few, if any, guidelines for how to define such habitat. Conservationists and scientists may view protecting part of the habitat of an endangered species as an ineffectual compromise, while managers may be under pressure to allow a range of human activities within the species' habitat. In the case of small cetaceans, establishing boundaries for such areas can also be complicated by their mobility, the fluid nature of their environment, and the often ephemeral nature of their habitat features. The convergence of multiple human impacts in coastal waters around the world is impacting many small cetaceans (and other species) that rely on these areas for feeding, reproducing, and resting. The ten guiding principles presented here provide a means to characterize the habitat needs of small, at-risk cetaceans, and serve as a basis for the delineation of ‘priority habitat’ boundaries. This conceptual approach should facilitate a constructive discourse between scientists and managers engaged in efforts to recover endangered species. The degree to which the recovery of an at-risk species can be reconciled with sustainable economic activity will depend in part on how well these principles are incorporated into the delineation of priority habitat.  相似文献