Modified Kadomtsev–Petviashvili equation for tsunami over irregular seabed

We derive an asymptotic equation governing the trans-ocean propagation of tsunami from source to the continental shelf. Focus is on disturbances originated from a slender fault of finite length. The variable sea depth is assumed to consist of a slowly varying mean and random fluctuations. The method of multiple scales is used to derive a Kadomtsev–Petviashvili equation with variable coefficients. Modifications by one- and two-dimensional random irregularities are shown to affect the wave speed, dissipation and additional dispersion. The result can be used to facilitate physical insight with modest numerical efforts.     

Assessing SWAT's performance in the Kaskaskia River watershed as influenced by the number of calibration stations used

The Future Midwestern Landscapes (FML) project is part of the U.S. Environmental Protection Agency's Ecosystem Services Research Program. The goal of the FML project is to quantify changes in ecosystem services across the Midwestern region as a result of the growing demand for biofuels. Watershed models are an efficient way to quantify ecosystem services of water quality and quantity. By calibrating models, we can better capture watershed characteristics before they are applied to make predictions. The Kaskaskia River watershed in Illinois was selected to investigate the effectiveness of different calibration strategies (single‐site and multi‐site calibrations) for streamflow, total suspended sediment (TSS) and total nitrogen (TN) loadings using the Soil and Water Assessment Tool. Four USGS gauges were evaluated in this study. Single‐site calibration was performed from a downstream site to an upstream site, and multi‐site calibration was performed and fine‐tuned based on the single‐site calibration results. Generally, simulated streamflow and TSS were not much affected by different calibration strategies. However, when single‐site calibration was performed at the most downstream site, the Nash–Sutcliffe efficiency (NSE) values for TN ranged between ?0.09 and 0.53 at the other sites; and when single‐site calibration was performed at the most upstream site, the NSE values ranged between ?8.38 and ?0.07 for the other sites. The NSE values for TN were improved to 0.5 – 0.59 for all four sites when multi‐site calibration was performed. The results of the multi‐site calibration and validation showed an improvement on model performance on TN and highlighted that multi‐site calibrations are needed to assess the hydrological and water quality processes at various spatial scales. Copyright © 2012 John Wiley & Sons, Ltd.     

Optimized object-based image classification: development of landslide knowledge decision support system

Landslide spatial decision support systems (LS-DSS) are computer-based systems that combine the geographic storage, search, and retrieval capabilities of geographic information systems with the decision models and optimizing algorithms used to support decision-making for landslide problems. This study proposes an optimization process of region object-oriented classification (ROC) to analyze the landslide image information. The surface information from the Wan Da reservoir area is collected and studied. We collected different spectrum with several texture information to analyze the surrounding area of the Wan Da reservoir. ROC is used to classify the landslide area. Entropy-based classification is used as a classifier in ROC to determine the landslide/nonlandslide area. The parameters of S (similarity) and A (area) are used and then the best combinations are found. An optimize algorithm is developed to access the above variables to perform the best classification outcomes. The relations of occurrence vs. non-occurrence of landslide which are linked to the attributes of land surface are studied. An improved translation model (Expert Knowledge Translation Platform) is also presented to increase the accuracy. This could be of help to manage/monitor the landslide area near the reservoir.     

Procedures,Resources and Selected Results of the Deep Ecliptic Survey

The Deep Ecliptic Survey is a project whose goal is to survey a largearea of the near-ecliptic region to a faint limiting magnitude (R ～24) in search of objects in the outer solar system. We are collectinga large homogeneous data sample from the Kitt Peak Mayall 4-m and CerroTololo Blanco 4-m telescopes with the Mosaic prime-focus CCD cameras.Our goal is to collect a sample of 500 objects with good orbits to furtherour understanding of the dynamical structure of the outer solar system.This survey has been in progress since 1998 and is responsible for 272designated discoveries as of March 2003. We summarize our techniques,highlight recent results, and describe publically available resources.     

Glyph and hyperstreamline representation of stress and strain tensors and material constitutive response

Results of numerical analyses of boundary value problems in geomechanics include output of three‐dimensional stress and strain states. Two‐dimensional plots of stress–stress or stress–strain quantities, often used to represent such output, do not fully communicate the evolution of stress and strain states. This paper describes the use of glyphs and hyperstreamlines for the visual representation of three dimensional stress and strain tensors in geomechanics applications. Glyphs can be used to represent principal stress states as well as normal stresses at a point. The application of these glyphs is extended in this paper to represent strain states. The paper introduces a new glyph, called HWY glyph for the representation of shear tensor components. A load step‐based hyperstreamline is developed to show the evolution of a stress or strain tensor under a general state of loading. The evolution of stress–strain states from simulated laboratory tests and a general boundary value problem of a deep braced excavation are represented using these advanced visual techniques. These visual representations facilitate the understanding of complex multidimensional stress–strain soil constitutive relationships. The visual objects introduced in this paper can be applied to stress and strain tensors from general boundary value problems. Copyright © 2003 John Wiley & Sons, Ltd.     

Stellar X-ray Sources in the Rosette Nebula

We present optical photometric and spectroscopic studies of ROSAT X-ray stellar sources in the Rosette Nebula star-forming region. The brightest X-ray sources are either massive stars or active T Tauri stars associated with the open cluster NGC 2244, or are foreground stars. Some of the spectra of the young stars newly identified in the region are presented.     

The importance of Fourier phases for the morphology of gravitational clustering

The phases of the Fourier modes appearing in a plane-wave expansion of cosmological density fields play a vital role in determining the morphology of gravitationally developed clustering. We demonstrate this qualitatively and quantitatively using simulations. In particular, we use cross-correlation and rank-correlation techniques to quantify the agreement between a simulated distribution and phase-only reconstructions. The phase-only reconstructions exhibit a high degree of correlation with the original distributions, showing how meaningful spatial reconstruction of cosmological density fields depends more on phase accuracy than on amplitudes.     

A two‐step‐ahead recurrent neural network for stream‐flow forecasting

In many engineering problems, such as flood warning systems, accurate multistep‐ahead prediction is critically important. The main purpose of this study was to derive an algorithm for two‐step‐ahead forecasting based on a real‐time recurrent learning (RTRL) neural network that has been demonstrated as best suited for real‐time application in various problems. To evaluate the properties of the developed two‐step‐ahead RTRL algorithm, we first compared its predictive ability with least‐square estimated autoregressive moving average with exogenous inputs (ARMAX) models on several synthetic time‐series. Our results demonstrate that the developed two‐step‐ahead RTRL network has efficient ability to learn and has comparable accuracy for time‐series prediction as the refitted ARMAX models. We then investigated the two‐step‐ahead RTRL network by using the rainfall–runoff data of the Da‐Chia River in Taiwan. The results show that the developed algorithm can be successfully applied with high accuracy for two‐step‐ahead real‐time stream‐flow forecasting. Copyright © 2003 John Wiley & Sons, Ltd.     

Stochastic simulation of bivariate gamma distribution: a frequency-factor based approach

A frequency-factor based approach for stochastic simulation of bivariate gamma distribution is proposed. The approach involves generation of bivariate normal samples with a correlation coefficient consistent with the correlation coefficient of the corresponding bivariate gamma samples. Then the bivariate normal samples are transformed to bivariate gamma samples using the well-known general equation of hydrological frequency analysis. We demonstrate that the proposed bivariate gamma simulation approach is capable of generating random sample pairs which not only have the desired marginal densities of component random variables but also their correlation coefficient. Scatter plots of simulated bivariate sample pairs also exhibit appropriate linear patterns (dependence structure) that are commonly observed in environmental and hydrological applications. Caution should also be exercised when specifying combinations of coefficients of skewness and the correlation coefficient for bivariate gamma simulation.