bluuebunny/crossref_metadata_2025_split huggingface dataset:
Minimum Local Emissivity Variance Retrieval of Cloud Altitude and Effective Spectral Emissivity—Simulation and Initial Verification
Authors: Huang Hung-Lung , Smith William L. , Li Jun , Antonelli Paolo , Wu Xiangqian , Knuteson Robert O. , Huang Bormin , Osborne Brian J. 
Published: May 2004

Abstract
This paper describes the theory and application of the minimum local emissivity variance (MLEV) technique for simultaneous retrieval of cloud pressure level and effective spectral emissivity from high-spectral-resolution radiances, for the case of single-layer clouds. This technique, which has become feasible only with the recent development of high-spectral-resolution satellite and airborne instruments, is shown to provide reliable cloud spectral emissivity and pressure level under a wide range of atmospheric conditions. The MLEV algorithm uses a physical approach in which the local variances of spectral cloud emissivity are calculated for a number of assumed or first-guess cloud pressure levels. The optimal solution for the single-layer cloud emissivity spectrum is that having the “minimum local emissivity variance” among the retrieved emissivity spectra associated with different first-guess cloud pressure levels. This is due to the fact that the absorption, reflection, and scattering processes of clouds exhibit relatively limited localized spectral emissivity structure in the infrared 10–15-μm longwave region. In this simulation study it is shown that the MLEV cloud pressure root-mean-square errors for a single level with effective cloud emissivity greater than 0.1 are ∼30, ∼10, and ∼50 hPa, for high (200– 300 hPa), middle (500 hPa), and low (850 hPa) clouds, respectively. The associated cloud emissivity root-mean-square errors in the 900 cm−1 spectral channel are less than 0.05, 0.04, and 0.25 for high, middle, and low clouds, respectively.
Can Satellite Sampling of Offshore Wind Speeds Realistically Represent Wind Speed Distributions? Part II: Quantifying Uncertainties Associated with Distribution Fitting Methods
Authors: Pryor S. C. , Nielsen M. , Barthelmie R. J. , Mann J. 
Published: May 2004

Abstract
Remote sensing tools represent an attractive proposition for measuring wind speeds over the oceans because, in principle, they also offer a mechanism for determining the spatial variability of flow. Presented here is the continuation of research focused on the uncertainties and biases currently present in these data and quantification of the number of independent observations (scenes) required to characterize various parameters of the probability distribution of wind speeds. Theoretical and empirical estimates are derived of the critical number of independent observations (wind speeds derived from analysis of remotely sensed scenes) required to obtain probability distribution parameters with an uncertainty of ±10% and a confidence level of 90% under the assumption of independent samples, and it is found that approximately 250 independent observations are required to fit the Weibull distribution parameters. Also presented is an evaluation of Weibull fitting methods and determination of the fitting method based on the first and third moments to exhibit the “best” performance for pure Weibull distributions. Further examined is the ability to generalize parameter uncertainty bounds presented previously by Barthelmie and Pryor for distribution parameter estimates from sparse datasets; these were found to be robust and hence generally applicable to remotely sensed wind speed data series.
Daytime Cloud Overlap Detection from AVHRR and VIIRS
Authors: Pavolonis Michael J. , Heidinger Andrew K. 
Published: May 2004

Abstract
Two algorithms for detecting multilayered cloud systems with satellite data are presented. The first algorithm utilizes data in the 0.65-, 11-, and 12-μm regions of the spectrum that are available on the Advanced Very High Resolution Radiometer (AVHRR). The second algorithm incorporates two different techniques to detect cloud overlap: the same technique used in the first algorithm and an additional series of spectral tests that now include data from the 1.38- and 1.65-μm near-infrared regions that are available on the Moderate Resolution Imaging Spectroradiometer (MODIS) and will be available on the Visible/Infrared Imager/Radiometer Suite (VIIRS). VIIRS is the imager that will replace the AVHRR on the next generation of polar-orbiting satellites. Both algorithms were derived assuming that a scene with cloud overlap consists of a semitransparent ice cloud that overlaps a cloud composed of liquid water droplets. Each algorithm was tested on three different MODIS scenes. In all three cases, the second (VIIRS) algorithm was able to detect more cloud overlap than the first (AVHRR) algorithm. Radiative transfer calculations indicate that the VIIRS algorithm will be more effective than the AVHRR algorithm when the visible optical depth of the ice cloud is greater than 3. Both algorithms will work best when the visible optical depth of the water cloud is greater than 5. Model sensitivity studies were also performed to assess the sensitivity of each algorithm to various parameters. It was found that the AVHRR algorithm is most sensitive to cloud particle size and the VIIRS near-infrared test is most sensitive to cloud vertical location. When validating each algorithm using cloud radar data, the VIIRS algorithm was shown to be more effective at detecting cloud overlap than the AVHRR algorithm; however, the VIIRS algorithm was slightly more prone to false cloud overlap detection.
A Probabilistic Model to Evaluate the Optimal Density of Stations Measuring Snowfall
Authors: Schneebeli Martin , Laternser Martin 
Published: May 2004

Abstract
Daily new snow measurements are very important for avalanche forecasting and tourism. A dense network of manual or automatic stations measuring snowfall is necessary to have spatially reliable data. Snow stations in Switzerland were built at partially subjective locations. A probabilistic model based on the frequency and spatial extent of areas covered by heavy snowfalls was developed to quantify the probability that snowfall events are measured by the stations. Area–probability relations were calculated for different thresholds of daily accumulated snowfall. A probabilistic model, including autocorrelation, was used to calculate the optimal spacing of stations based on simulated triangular grids and to compare the capture probability of different networks and snowfall thresholds. The Swiss operational snow-stations network captured snowfall events with high probability, but the distribution of the stations could be optimized. The spatial variability increased with higher thresholds of daily accumulated snowfall, and the capture probability decreased with increasing thresholds. The method can be used for other areas where the area–probability relation for threshold values of snow or rain can be calculated.
Microphysical Characteristics of Tropical Updrafts in Clean Conditions
Authors: Stith Jeffrey L. , Haggerty Julie A. , Heymsfield Andrew , Grainger Cedric A. 
Published: May 2004

Abstract
The distributions of ice particles, precipitation embryos, and supercooled water are examined within updrafts in convective clouds in the Amazon and at Kwajalein, Marshall Islands, based on in situ measurements during two Tropical Rainfall Measuring Mission field campaigns. Composite vertical profiles of liquid water, small particle concentration, and updraft/downdraft magnitudes exhibit similar peak values for the two tropical regions. Updrafts were found to be favored locations for precipitation embryos in the form of liquid or frozen drizzle-sized droplets. Most updrafts glaciated rapidly, removing most of the liquid water between −5° and −17°C. However, occasional encounters with liquid water occurred in much colder updraft regions. The updraft magnitudes where liquid water was observed at cold (e.g., −16° to −19°C) temperatures do not appear to be stronger than updrafts without liquid water at similar temperatures, however. The concentrations of small spherical frozen particles in glaciated regions without liquid water are approximately one-half of the concentrations in regions containing liquid cloud droplets, suggesting that a substantial portion of the cloud droplets may be freezing at relatively warm temperatures. Further evidence for a possible new type of aggregate ice particle, a chain aggregate found at cloud midlevels, is given.
Performance of six severity-of-illness scores in cancer patients requiring admission to the intensive care unit: a prospective observational study
Authors: Soares Márcio , Fontes Flávia , Dantas Joana , Gadelha Daniela , Cariello Paloma , Nardes Flávia , Amorim César , Toscano Luisa , Rocco José R 
Published: May 2004

Abstract
Introduction
The aim of this study was to evaluate the performance of five general severity-of-illness scores (Acute Physiology and Chronic Health Evaluation II and III-J, the Simplified Acute Physiology Score II, and the Mortality Probability Models at admission and at 24 hours of intensive care unit [ICU] stay), and to validate a specific score – the ICU Cancer Mortality Model (CMM) – in cancer patients requiring admission to the ICU.

Methods
A prospective observational cohort study was performed in an oncological medical/surgical ICU in a Brazilian cancer centre. Data were collected over the first 24 hours of ICU stay. Discrimination was assessed by area under the receiver operating characteristic curves and calibration was done using Hosmer–Lemeshow goodness-of-fit H-tests.

Results
A total of 1257 consecutive patients were included over a 39-month period, and 715 (56.9%) were scheduled surgical patients. The observed hospital mortality was 28.6%. Two performance analyses were carried out: in the first analysis all patients were studied; and in the second, scheduled surgical patients were excluded in order to better compare CMM and general prognostic scores. The results of the two analyses were similar. Discrimination was good for all of the six studied models and best for Simplified Acute Physiology Score II and Acute Physiology and Chronic Health Evaluation III-J. However, calibration was uniformly insufficient (P < 0.001). General scores significantly underestimated mortality (in comparison with the observed mortality); this was in contrast to the CMM, which tended to overestimate mortality.

Conclusion
None of the model scores accurately predicted outcome in the present group of critically ill cancer patients. In addition, there was no advantage of CMM over the other general models.
An amplitude-based multiazimuthal approach to mapping fractures using P-wave 3D seismic data
Authors: Luo Mu , Evans Brian J. 
Published: May 2004

We have tested an amplitude-based multiazimuthal approach for mapping fractures which requires only a simple azimuth-offset sorting process. By displaying the amplitudes of all traces collected within a superbin, the method predicts fractures by mapping P-wave amplitude variations, in which a lineation within the map indicates the presence and the orientation of fractures within the superbin. Test results using physical model and field data sets suggest that the amplitude-based multiazimuthal approach could help to determine the presence of multiple fracture sets in a single layer, which may be expressed through subtle variations in P-wave multiazimuthal seismic reflections. Our experiments with a physical model containing manmade vertical fractures suggest that transmission effects could be one of the dominant factors which control azimuthal amplitude versus offset (AVO) behavior.The technique described in this paper can operate on any 3D P-wave seismic data with wide azimuth and offset distributions.
Accurate spatial directional derivative: Antialiasing Kirchhoff migration
Authors: Wang Chengshu 
Published: May 2004

Applying a low‐pass filter to each input trace before performing migration is a common antialiasing method used in Kirchhoff 3D migration. The spatial directional derivative that gives the tangent plane direction of the reflector is key in determining the antialiasing frequency limits. In this paper, we present the formula of the traveltime gradient for the diffraction hyperboloid. We also deduce the formula of the vertical traveltime gradient for the reflection ellipsoid, which can be used to construct the antialiasing low‐pass filter after migration. The migration stretch is easily computed from the ratio of gradient expressions obtained for the reflection ellipsoid and the diffraction hyperboloid. The gradient formula includes magnitude and direction. The correct direction of the gradient function is from an image point to the dip‐moveout image point (ρ* direction) on the surface. The gradient is not in the direction from the image point to the midpoint (ρ direction) as has been previously concluded. The correct spatial directional derivative along ρ is given, and it is slightly less than the gradient norm. We also prove that the true direction of the tangent plane on the reflection ellipsoid can be determined by the gradient. We introduce the directional derivative value along ρ that can be approximately applied to calculate the high‐frequency limit. Compared with the maximum directional derivative value (gradient norm), the directional derivative is relatively accurate and is much easier to calculate for use in antialiasing. The different results from the new method and the former method are compared. Numerical examples compare the performance of the different formulae.
Liquefaction Testing of Layered Sand-Gravel Composites
Authors: Amini F , Chakravrty A 
Published: May 2004

AbstractThe liquefaction characteristics of stratified sand-gravel composites are currently poorly understood, yet these materials are often encountered in alluvial and hydraulic fill deposits. To investigate the effect of soil layering on the cyclic resistance of sand-gravel composites, a research program was undertaken in which a series of undrained cyclic triaxial tests was performed on both uniform and layered sand-gravel composite specimens with gravel contents of 10, 30, 50, and 70%. Two methods of sample preparation were used for each soil type. These methods included pluviation through air (representing homogeneous soil conditions) and wet pluviation (representing layered soil conditions). The confining pressures ranged from 50 to 250 KPa. The results indicated that the method of sample preparation and the different soil fabric did not significantly influence the liquefaction resistance of the sand-gravel composites. It is also shown that the effects of confining pressure are similar for both homogeneous and layered soil conditions.
Reduction of Boundary Friction in Model Tests
Authors: Fang YS , Chen T-J , Holtz RD , Lee WF 
Published: May 2004

Abstract
To model plane-strain conditions in the laboratory, the frictional resistance between the soil and side walls of the soil box should be reduced as much as possible. Methods commonly employed for this purpose include a latex sheet with silicon grease (“grease method”) or multiple layers of thin plastic sheeting (“plastic sheet method”). Interface friction angles are often measured by direct shear-type tests.
In this paper, a new sliding block testing device for measuring the friction at the interface between soil and different materials at low stress conditions is described. Interface friction angles for eight different methods for reducing boundary friction were investigated using the proposed testing method. Test results indicated that the friction angle obtained with the plastic sheet method is nearly independent of the normal stress. On the other hand, the interface friction angle of the grease method was quite high under low normal stress conditions. Thus, the plastic sheet method appears to be a more appropriate technique under low normal stress conditions to reduce the boundary friction for laboratory scale model tests. As compared with the grease method, advantages of the plastic sheet method include constant friction angles, less time for preparation and cleanup, and lower cost.
To investigate their applicability, both lubrication systems were used in some large-scale laboratory-retaining wall experiments. Earth pressure measurements obtained near the sidewalls indicated that, under a low normal stress, the plastic sheet method was more effective in reducing sidewall friction.
Free Swell Ratio and Clay Mineralogy of Fine-Grained Soils
Authors: Prakash K , Sridharan A 
Published: May 2004

Abstract
The dominant clay minerals present in fine-grained soils control the physical and engineering behavior of the soils. Determination of the dominant clay minerals in the soils, at present, requires procedures involving sophisticated instrumentation and the knowledge to interpret the results from such tests. A user-friendly approach based on free swell ratio, defined as the ratio of the equilibrium sediment volume of 10-g oven dried soil in distilled water to that in carbon tetra chloride, has emerged as a simple methodology to predict the clay mineral(s) present in the soil as either montmorillonitic or kaolinitic type quite satisfactorily. The validation of the proposed free swell ratio method has been done with exhaustive experimental data.
Determination of the Diffusion Coefficient of Oxygen for a Cover System Including a Pulp and Paper By-Product
Authors: Cabral AR , Tremblay P , Lefebvre G 
Published: May 2004

Abstract
Among the several solutions that have been proposed to curb the problem posed by the generation of acid rock drainage (ARD), the placement of covers with capillary barrier effect (CCBE) has received particular attention. With the creation of a capillary barrier, oxygen has to migrate through a nearly saturated layer, a much slower process than in air. As a consequence, its availability is drastically reduced, reducing ARD generation. An experimental procedure was developed to obtain the diffusion coefficient of oxygen through compacted deinking residues, an organic matter-rich by-product of paper recycling. With the oxygen concentrations obtained as a function of time, it was possible to deduce the diffusion coefficients based on the best reproductions of laboratory results, using the computer code POLLUTE v.6. As expected, it was found that the diffusion coefficient—and the associated flux—is highly influenced by the degree of saturation of the sample. Beyond a threshold in the vicinity of 85%, a one order of magnitude drop in the diffusion coefficient was observed. A comparison of the results obtained with previously published data shows that deinking residues constitute a very effective oxygen barrier material due both to its ability to maintain a high degree of saturation and to rapidly consume oxygen. Given the latter, special care was needed in defining the most appropriate equipment design, sample preparation method, and testing procedure.
Granular Pile Anchor Foundation (GPAF) System for Improving the Engineering Behavior of Expansive Clay Beds
Authors: Phanikumar BR , Sharma RS , Srirama Rao A , Madhav MR 
Published: May 2004

Abstract
Several innovative foundation techniques have been suggested for reducing the detrimental heave of foundations in expansive clays. This paper presents another innovative technique in the form of a granular pile anchor-foundation (GPAF) system for arresting heave and for improving the overall engineering behavior of expansive clay beds. In the GPAF system, the foundation is anchored at the bottom of the granular pile to an anchor plate through an anchor rod. As a result, heave of the foundation is reduced. The laboratory model tests using this new concept of the GPAF system revealed that the heave of the expansive clay beds was reduced by about 96 %. The development of final heave was faster in the case of the expansive clay beds reinforced with the GPAF system. The undrained strength of the clay surrounding the granular pile anchor improved by about 20 %. The tests on two-group granular pile anchors indicated that heave was reduced to a minimum value when the spacing between the granular pile anchors was kept at twice the pile diameter. The compressive load response of the expansive clay bed reinforced with granular pile anchors also improved. The pull-out load of the granular pile anchors increased with increasing diameter and the relative density of the pile.
Design of a Measurement Program for a Bench-Scale PVD Remediation System using Bayesian Updating
Authors: Welker AL , Gilbert RB 
Published: May 2004

Abstract
Two experiments were undertaken to study the effectiveness of a remediation system that utilizes prefabricated vertical drains. The measurement program, which included obtaining head and concentration measurements for these experiments, was designed using a Bayesian decision framework. The First-Order Second-Moment Bayesian method was employed to select the best location for the observation wells as well as when to take the measurements and how long the experiment should last. The selected measurementscheme balanced the reduction in uncertainty realized through taking the head and concentration measurements with the difficulty in obtaining those measurements.
A Flume for Assessing Flux Boundary Characteristics in Rainfall-Induced Slope Failure Studies
Authors: Rahardjo H , Lee TT , Leong EC , Rezaur RB 
Published: May 2004

Abstract
Rainfall-induced slope failure studies and slope hydrological behavior studies often require an assessment of the flux boundary characteristics of a slope. However, quantification of the flux boundary conditions across a slope surface with respect to rainfall, runoff, and infiltration is difficult. This paper introduces the design and field installation of a flume for high resolution monitoring of runoff data from a small catchment, particularly for rainfall-induced slope failure studies. The features of the flume include reliable and continuous runoff measurement at high resolution, options for accommodating various flow rates as dictated by the slope size, and portability. The flume can be used to quantify the flux boundary conditions required for seepage analyses associated with rainfall-induced slope failure studies.
Use of “Zero Controlled Gradient” Tests to Determine EOP Compression Behavior
Authors: Sheahan TC , DeGroot DJ , Fu Q , Ryan RM 
Published: May 2004

Abstract
This paper describes the use of a new consolidation testing method, known as the “zero controlled gradient” (zero CG) test, to measure the one-dimensional (1-D), end-of-primary (EOP) consolidation behavior of soft soils. The conventional incremental loading (IL) consolidation test remains the most common test method for measuring 1-D consolidation behavior; however, data reduction requires graphical constructions to obtain key consolidation parameters. In addition, the IL test provides data only at intervals dictated by the loading increments used, leading to discontinuous stress-strain data that may mask or distort true soil consolidation behavior. The zero CG test mimics the EOP behavior by maintaining approximately zero excess pore pressure throughout the soil specimen as it is being continuously loaded, and thus avoids the problem of strain rate selection in the constant rate of strain (CRS) test. Zero CG tests were performed on three natural soils using a computer-automated Rowe consolidation cell, and these results were compared to conventional IL consolidation tests on the same soils. In general, for a given soil, the results from the two tests were consistent. However, the zero CG results had these advantages: defining the compression curve more accurately and continuously around the preconsolidation stress (σ′p), and giving higher, more realistic compression index values beyond σ′p. The major drawback of the zero CG test is that coefficient of consolidation (cv) data cannot be obtained due to the lack of excess pore pressure. The zero CG test offers both a practical and research tool for determining EOP consolidation states, and can eliminate strain rate problems inherent in both IL and CRS tests.