An improved genetic programming to SSM/I estimation typhoon precipitation over ocean     

Li Chen  Keh‐Chia Yeh  Hsiao‐Ping Wei  Gin‐Rong Liu 《水文研究》2011,25(16):2573-2583

This article proposes an improved multi‐run genetic programming (GP) and applies it to estimate the typhoon rainfall over ocean using multi‐variable meteorological satellite data. GP is a well‐known evolutionary programming and data mining method used to automatically discover the complex relationships among nonlinear systems. The main advantage of GP is to optimize appropriate types of function and their associated coefficients simultaneously. However, the searching efficiency of traditional GP can be decreased by the complex structure of parse tree to represent the multiple input variables. This study processed an improvement to enhance escape ability from local optimums during the optimization procedure. We continuously run GP several times by replacing the terminal nodes at the next run with the best solution at the current run. The current method improves GP, obtaining a highly nonlinear meaningful equation to estimate the rainfall. In the case study, this improved GP (IGP) described above combined with special sensor microwave imager (SSM/I) seven channels was employed. These results are then verified with the data from four offshore rainfall stations located on islands around Taiwan. The results show that the IGP generates sophisticated and accurate multi‐variable equation through two runs. The performance of IGP outperforms the traditional multiple linear regression, back‐propagated network (BPN) and three empirical equations. Because the extremely high values of precipitation rate are quite few and the number of zero values (no rain) is very large, the underestimations of heavy rainfall are obvious. A simple genetic algorithm was therefore used to search for the optimal threshold value of SSM/I channels, detecting the data of no rain. The IGP with two runs, used to construct an appropriate mathematical function to estimate the precipitation, can obtain more favourable results from estimating extremely high values. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Depth zonation and bathymetric trends of deep-sea megafaunal scavengers of the Hawaiian Islands     

John Yeh  Jeffrey C. Drazen 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(2):251-266

The deep sea has been shown to exhibit strong depth zonation in species composition and abundance. Examination of these patterns can offer ecological insight into how organisms adapt and respond to changing environmental parameters that co-occur with depth. Here we provide the first tropical study on bathymetric zonation and other depth-related trends (size, abundance, and species richness) spanning shelf to abyssal depths of scavenging megafauna. Baited time-lapse free-vehicle cameras were used to examine the deep-sea benthic and demersal scavenging communities of the Hawaiian Islands, an area for which the biology and ecology have remained poorly studied below 2000 m. Twenty-two deployments ranging in depth from 250 to 4783 m yielded 37 taxa attracted to bait, including the first known occurrence of the family Zoarcidae in the Hawaiian Islands. Cluster analysis of Bray–Curtis similarity of species peak abundance (n_max) revealed four main faunal zones (250–500, 1000, 1500–3000, and ?4000 m) with significant separation (ANOSIM, global R=0.907, p=0.001) between designated depth groups. A major faunal break was identified at the 500–1000 m transition where species turnover was greatest, coinciding with the location of the local oxygen minimum zone. Dominance in species assemblage shifted from decapod crustaceans to teleosts moving from shallow to deeper faunal zones. Significant size differences in total length with depth were found for two of the four fish species examined. A logarithmic decline was observed in scavenger relative abundance with depth. Evidence of interaction between scavenging species was also noted between Synaphobranchus affinis and Neolithodes sp. (competition) and Histiobranchus sp. and aristeid shrimp (predation), suggesting that interactions between scavengers could influence indices of abundance generated from baited camera data.  相似文献   

Latitudinal profile of UV nightglow and electron precipitations     

A.V. Dmitriev  H.-C. Yeh  V.I. Galkin  B.A. Khrenov  L.L. Lazutin  S.I. Svertilov 《Planetary and Space Science》2011,59(8):733-740

We studied experimental data on ultra-violet (UV) nightglow in the wavelength range 300-400 nm, and energetic electron fluxes measured by low-altitude polar satellite Universitetskii-Tatiana. From statistical analysis we have found three latitudinal regions of enhanced UV emission at low, middle and high latitudes. Modeling the electron precipitations to the atmosphere gave numerical estimation of the generated UV radiation. We found that the stable and quasi-stable fluxes of electrons precipitating at middle and low latitudes are too weak to explain the observed intensities of UV radiation. The high-latitude UV nightglow with intensity of several kiloRayleighs results from particle precipitation in the regions of aurora and outer radiation belt. The low-latitude UV enhancements of several hundreds Rayleighs can be related to the emission of mesospheric atomic oxygen whose concentration increases substantially at latitudes from 20° to 40°. A mechanism of the mid-latitude UV enhancements is still unknown and requires further investigations.  相似文献   

Decadal change in relationship between western North Pacific tropical cyclone frequency and the tropical Pacific SST   总被引：1，自引：0，他引：1  

Sang-Wook Yeh  Sok-Kuh Kang  Ben P. Kirtman  Joo-Hong Kim  Min-Ho Kwon  Cheol-Ho Kim 《Meteorology and Atmospheric Physics》2010,106(3-4):179-189

In this study, we examine the relationship between the number of tropical cyclones (TCs) in the western North Pacific and the tropical Pacific sea surface temperature (SST) during the main TC season (July–November) for the period of 1965–2006. Results show that there are periods when TC frequency and the tropical Pacific SST are well correlated and periods when the relationship breaks down. Therefore, decadal variation is readily apparent in the relationship between the TC frequency and the SST variations in the tropical Pacific. We further examine the oceanic and atmospheric states in the two periods (i.e., 1979–1989 vs. 1990–2000) when the marked contrast in the correlation between the TC frequency and the tropical Pacific SST is observed. Before 1990, the analysis indicates that oceanic conditions largely influenced anomalous TC frequency, whereas atmospheric conditions had little impact. After 1990, there the reverse appears to be the case, i.e., atmospheric conditions drive anomalous TC frequency and oceanic conditions are relatively unimportant. A role of atmosphere and ocean in relation to the TC development in the western North Pacific changes, which is consistent with the change of the correlations between the TC frequency and the tropical Pacific SST.  相似文献   

Analysis of atmospheric turbidity levels at Taichung Harbor near the Taiwan Strait     

Chih-Chung Wen  Hui-Hsuan Yeh 《Atmospheric Research》2009,94(2):168-177

In this study, two universal turbidity parameters, the Angstrom turbidity coefficient and Linke turbidity factor, are applied to study the atmospheric turbidity characteristics of Taichung Harbor. Meteorological parameter values were measured during 2004 and 2005 at the Wuchi weather station of the Taiwan Central Weather Bureau, near the Taiwan Strait. Results based on the Angstrom turbidity models (β_Lou, β_Pin, and β_Vis) indicated that annual mean values of the Angstrom turbidity coefficients were 0.174, 0.21 and 0.201, respectively. Four sets of Linke turbidity factors (T_Lin, T_Lou, T_Pin and T_Vis) were calculated using the original Linke method and the Dogniaux method, incorporating the computed Angstrom turbidity coefficients (β_Lou, β_Pin and β_Vis); the resultant values were 4.30, 6.40, 7.10 and 6.95, respectively. The monthly average values, frequency of occurrence, and cumulative frequency distributions were calculated using different models to describe the clear-sky atmospheric conditions at Taichung Harbor. The frequency results show that for over 50% of the dataset, three sets of Angstrom turbidity coefficients fell between 0.15 and 0.18, and four sets of Linke turbidity factors (T_Lin, T_Lou, T_Pin and T_Vis) fell between 4.0 and 6.5. Thus, for 50% of cloudless days, the sky can be between turbid and clear over Taichung Harbor. Furthermore, the results reveal that for 30% of the dataset, three Angstrom sets of turbidity coefficients (β_Lou, β_Pin, and β_Vis) exceed 0.2 and four sets of Linke turbidity factors (T_Lin, T_Lou, T_Pin and T_Vis) exceed 5.0. This indicates that 30% of cloudless sky conditions can be considered turbid to very turbid.  相似文献   

Greening western China: A critical view   总被引：2，自引：0，他引：2  

Emily T. Yeh 《Geoforum》2009,40(5):884-404

The dominant narrative in a growing literature about China’s environment conceptualizes a series of recent large-scale ecological construction projects, particularly in western China, as evidence of a teleological graduation into eco-rational modernity, in which environmental improvement and economic growth are intertwined in a virtuous, mutually reinforcing circle. Such ecological modernization narratives take for granted both a crisis of ecological degradation, and the premise that the “greening” of the state will have environmental improvement as its primary outcome. The article reviews recent research on ecological construction projects to protect forests and grasslands in China’s west, which have been identified as major components of China’s ecological modernization goals. It demonstrates the limitations of an ecological modernization framework for analyzing these projects, and argues instead for a critical political ecology analysis, which examines the distributive effects of these projects and employs an analytic of governmentality. Ecological construction is more productively understood as a set of discursive practices that authorize differential interventions through processes of internal territorialization, rework the relationship between different categories of citizens and the state, and produce subjects, whose desires may or may not align with those desired by state institutions.  相似文献   

Neptune migration model with one extra planet     

Lun-Wen Yeh  Hsiang-Kuang Chang 《Icarus》2009,204(1):330-345

We explore conventional Neptune migration model with one additional planet of mass at 0.1-2.0M_⊕. This planet inhabited in the 3:2 mean motion resonance with Neptune during planet migration epoch, and then escaped from the Kuiper belt when jovian planets parked near the present orbits. Adding this extra planet and assuming the primordial disk truncated at about 45 AU in the conventional Neptune migration model, it is able to explain the complex structure of the observed Kuiper belt better than the usual Neptune migration model did in several respects, which are the following. (1) High-inclination Plutinos with i?15-35° are produced. (2) Generating the excitation of the classical Kuiper belt objects, which have moderate eccentricities and inclinations. (3) Producing the larger ratio of Neptune’s 3:2 to 2:1 resonant particles, and the lower ratio of particles in the 3:2 resonance to those in the classical belt, which may be more consistent with observations. (4) Finally, several Neptune’s 5:2 resonant particles are obtained. However, numerical experiments imply that this model is a low-probability event. In addition to the low probability, two features produced by this model may be inconsistent with the observations. They are small number of low-inclination particles in the classical belt, and the production of a remnant population with near-circular and low-inclination orbit within . According to our present study, including one extra planet in the conventional Neptune migration model as the scenario we explored here may be unsuitable because of the low probability, and the two drawbacks mentioned above, although this model can explain better several features which is hard to produce by the conventional Neptune migration model. The issues of low-probability event and the lack of low-inclination KBOs in the classical belt are interesting and may be studied further under a more realistic consideration.  相似文献   

Considering the effect of body force for regional land displacements     

Ruey-Hsing Lu  Hund-Der Yeh 《国际地质力学数值与分析法杂志》1994,18(3):145-160

In this study, a general mathematical model was developed for land displacements that occur as a result of the pressure decline in confined and/or phreatic aquifers. Two equations were developed by employing the equilibrium (force balance) equation and the flow equation in a deforming aquifer system. Both of these equations were integrated over the thickness of the aquifer system once a regional model had been formulated. The change of the body force in saturated and unsaturated zones of aquifers was considered in the derivation of the equilibrium equation. It was assumed that no external loading or force acting on the aquifer system was present. Two coupled equations expressed in terms of the averaged dilation and pressure were then obtained. The pumping data sets given in the papers of Bear and Corapcioglu^1,2 in 1981 and 1983 were analysed. Drawdown and displacements in a confined aquifer were demonstrated to be identical to those estimated by Bear and Corapcioglu.¹ In the case of a phreatic aquifer, however, the results estimated by the present approach were slightly different from those obtained by Corapcioglu and Bear.² The discrepancies in the results are possibly due to errors in the equations presented by Corapcioglu and Bear.² The present approach was able to avoid several assumptions and complex procedures used by Bear and Corapcioglu,^1,2 especially in the case of a phreatic aquifer, by taking into account the change in the body force.  相似文献   

Seismic hazard and uncertainty analysis of the Taiwan area     

Chin-Hsiung Loh  Fwu-Shing Baw

Yeong-Tein Yeh 《Soil Dynamics and Earthquake Engineering》1992,11(8):497-508

The objectives of this paper are (1) to obtain estimates on the effect of uncertainties of the hazard model, and (2) to evaluate the seismic hazard in Taiwan for structural analysis and design purposes. The seismic hazard in the Taiwan area is presented in terms of an iso-acceleration map. Such a map is developed for return periods of peak ground acceleration of 225 years and 475 years. The contour map of b-values and mean occurence rates for this region is also presented. Uncertainty analyses of model parameters in hazard analysis are concentrated on the analysis of dispersion of PGA values and the probabilistic modeling of stationary and nonstationary Poisson models of occurrences. Th e overall results are considered to be conservative since for most uncertainty analyses the more conservative values are used.  相似文献   

Inexpensive Access Tube Installation of Tensiometers Below a Flowing Stream     

Laurel J. Lacher  Thomas Maddock III  T.-C. Jim Yeh 《Ground Water Monitoring & Remediation》1997,17(3):76-77

  相似文献