bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructure and Texture of in Situ Heavily Drawn Cu–Nb Composites
Authors: Popova E. N. , Popov V. V. , Rodionova L. A. , Sudareva S. V. , Romanova E. P. , Vorobyova A. E. , Hlebova N. E. , Pantsyrnyi V. I. , Shikov A. K.
Published: April 2008

Heavily cold drawn in situ Cu–Nb composites have been investigated by transmission
electron microscopy (TEM) and X‐ray analysis. Dislocation density in the copper matrix
has been shown to change only slightly in the investigated drawing ratio range because of
the development of stage IV of deformation. In Nb filaments dislocation density in the
investigated range at first increases with deformation and then drops at the highest
drawing ratio. At intermediate deformation niobium grains consist of fine blocks
separated by low‐angle dislocation boundaries. At drawing, fibre texture develops in
both phases, with 〈111〉 and 〈100〉 axis for the copper matrix and 〈110〉 axis for niobium
filaments. Besides, niobium filaments acquire ribbon‐like form, and their grains possess
certain orientation, namely, in interlacing grains crystallographic {311}, {100} and {111}
planes are parallel to each other and to the filament plane, i.e., the rolling texture with
{311}〈110〉, {100}〈110〉 and {111}(110) components is forming within every filament.
In‐Plane Texturing in Sputtered Films
Authors: Whitacre J. F. , Yalisove S. M. , Bilello J. C.
Published: April 2008

Films consisting of Mo, Cr, and Ta have all been found to display well‐defined biaxial
textures when grown under certain conditions. A well‐defined out‐of‐plane texture evolves
within the first ~ 100 nm of the film, followed by the evolution of a preferred crystallographic
orientation in the plane of the film. These effect were studied using X‐ray pole figure
analysis, scanning electron microscopy (SEM), transmission electron microscopy
(TEM), transmission electron diffraction (TED), and high resolution grazing incidence
X‐ray scattering (GIXS). It has been found that in-plane texture evolves only when there
is, on average, oblique adatom flux incident onto the substrate. Further, the type of out‐of‐plane texture can be controlled by altering the deposition conditions. Parameters including cathode‐to‐substrate distance, deposition rate, average angle of adatom incidence,
and sputter gas pressure, have been shown to determine the type out‐of‐plane
texture, as well as the rate of in‐plane texture evolution. The studies conducted have shown
that it is possible to create and control biaxially textured films and multilayers made of a
variety of materials. A recent model which describes this phenomena is discussed.
Spatial Orientation Distribution of Crystallites in Cold‐Rolled and in Annealed Sheets of Deep‐Drawing Phosphorus Steel
Authors: Hu Hsun
Published: April 2008

The cold‐rolling and annealing textures of a deep‐drawing
phosphorus steel have been studied by the spatial orientation distribution
of the crystallites. The characteristics of the orientation
distribution functions of the as‐cold‐rolled and of the annealed
sheets were closely examined. The observed features suggest that
the annealing texture is originated by microband or transition‐band
nucleation, followed by the growth of recrystallized grains at the
expense of the matrix deformation textures. The crystallite orientation
distribution of the annealed sheet of the deep‐drawing phosphorus
steel is clearly different from that of the annealed sheet
of deep‐drawing aluminum‐killed steels.
The Resolution of Orientation Space With Reference to Pole‐Figure Resolution
Authors: Imhof János
Published: April 2008

The orientation distribution function depends on the measured pole‐figure data structure. With reference to the divisions of the pole‐figure the orientation space is divided into classes, such that contain orientations indistinguishable on the basis of pole‐figure data. These classes should refer to distinguishable values of the orientation distribution function. Divisions of orientation space are considered in formulating the fundamental equation of texture analysis. Probabilistic interpretation of the fundamental equation is formulated.
Reaction and Geometrical Softening in Granitoid Mylonites
Authors: Williams Graham , Dixon John
Published: April 2008

The microstructures of granitoid mylonites from Locquirec, N. Brittany; Ben Arnaboll, NW Scotland; and Cap de Creus, NE Spain show a similarity of development as a response to both geometric and reaction softening. A combination of these two softening processes leads to a concentration of deformation in the respective shear zones. Geometric softening leads to a rotation of quartz lattices for easy slip and is accompanied by dynamic recrystallization. Metamorphic reactions involving the breakdown of orthoclase and plagioclase feldspar to fine aggregates of muscovite plus quartz provide a secondary softening process which further concentrates deformation. These reactions indicate fluid mobility in the shear zones during deformation processes.
Calculation of Augmented Jacobi Polynomials by Means of a Recurrence Relation
Authors: Liang Zhi-de , Xu Jia-Zheng , Wang Fu
Published: April 2008

A recurrence relation for Zℓmn(ξ) is deduced from the
recurrence relations for Jacobi polynomials. Based on this relation
an ALGOL‐60 program has been written for efficiently calculating
the Zℓmn(ξ) required in ODF analysis.
On the Stress Dependence of Subgrain Size
Authors: Edward G. H. , Etheridge M. A. , Hobbs B. E.
Published: April 2008

A simple model of the dynamic balance between deformation induced dislocation generation and climb controlled dislocation annihilation in subgrain walls is outlined. This results in a stress‐subgrain size relationship which involves various material properties, including the creep stress exponent and the creep diffusivity.

Assuming a fixed slip distance for mobile dislocations, the theory predicts that the subgrain
size (d) depends on the stress (σ) as d4 ∝ σ−n, where n is the creep exponent, and the proportionality constant is dependent on material properties, temperature, and other environmental variables. This theoretical prediction is satisfactorily compared with published experimental results for
a variety of materials.

The implications of the environmental dependence of the stress‐subgrain size relation with
regard to its use as a palaeopiezometer in naturally deformed minerals are discussed.
Neutron Diffraction Texture Analysis Using a 2θ‐Position Sensitive Detector
Authors: Bunge H. J. , Wenk H. R. , Pannetier J.
Published: April 2008

A method for pole figure measurements in textured samples using neutron diffraction and a
position sensitive detector is described. The position sensitive detector allows one to record the whole 2ϑ‐spectrum of one sample position simultaneously, i.e. in reasonable time. The availability of the complete 2ϑ spectrum allows separation of overlapping peaks by a deconvolution process. A second independent method of peak separation is based on the crystallographic relations between peaks of various indices (hkl). The method allows extraction of the maximum possible information about the texture out of a polycrystal diffraction spectrum. It is thus especially suited to texture studies in materials having complex diffraction spectra with overlapping peaks, i.e. materials with low crystal symmetry and large lattice parameters as they are frequently encountered in geology.
Texture and Grain Growth during the Annealing of Ice
Authors: Wilson C. J. L.
Published: April 2008

Changes in microstructure and texture are described in polycrystalline ice compressed at temperatures of –10 and –1℃ and annealed for various times at –1℃ without a load. The
microstructures, obtained under these conditions, were studied by means of polarized light
microscopy, both mean and maximum grain sizes were determined. In the colder finer grained
samples (–10℃) the grain size increase during annealing was not as rapid as the coarser hot
worked (–1°) samples. Little textural change was observed in the annealed hot worked samples,
however the strong preferred orientation of the colder samples was destroyed with annealing.
The change in texture corresponded to a decrease in the grain growth rate and the formation
of a stable grain structure. Increasing strain and decreasing the deformation temperature both
reduce annealing time and the annealed grain size.
Apparatus for Dynamical Texture Measurements by Neutron Diffraction Using a Position Sensitive‐ Detector
Authors: Jensen D. Juul , Kjems J. K.
Published: April 2008

A new apparatus for dynamical texture measurements using neutron diffraction has been
developed. A variable wavelength neutron spectrometer has been modified to incorporate a linear
position‐sensitive detector. The sample is orientated by a fully automatic Euler goniometer, and
it can be heated by a stream of hot air at rates up to 200℃/min. A quarter of a complete pole
figure can be recorded in 14 minutes with an accuracy, determined by counting statistics, of
2–3%. The experimental set‐up is described in the present paper and the performance, including
sources of systematical errors, is discussed. Finally the viability of this apparatus is demonstrated
by studies of the recrystallization kinetics of 95% cold rolled copper.
Observations of Microcrystalline Plagioclase Spherulites With the Transmission Electron Microscope
Authors: Bailey R. Mark , Wenk H. R.
Published: April 2008

Two thin sections of macroscopic plagioclase spherulites of approximately 1 cm diameter found in a rhyolitic glass have been studied with the transmission electron microscope (TEM). Orientations of the thin sections were chosen to give views down and perpendicular to the major fiber axis. The crystalline fiber phase is high albite microtwinned on the (010) composition plane, elongated in the major growth direction, [001]. Fiber morphology is non‐polygonal with an average fiber diameter of 2000 Å perpendicular to c*. Fibers are separated by a non‐crystalline residuum layer of approximately constant thickness (300–500 Å). Microtwinning relationships,
as well as selected area diffraction (SAD) patterns, reveal both crystallographic and non‐crystallographic branching with the former unexpectedly dominant.
The Development of Deformation Textures Described by an Orientation Flow Field
Authors: Bunge H. J. , Esling C. , Dahlem E. , Klein H.
Published: April 2008

The mean orientation change δg of crystals of the orientation g in a polycrystalline
material due to plastic deformation can be described (under certain assumptions) by an
orientation flow field δg(g) = dη·ν(g) where
dη is the absolute value of a small deformation step.
The flow field ν(g) is a vector field in the orientation space g = {φ1, Φ, φ2}
which must obey a continuity equation. The flow field describes the texture changes due to
plastic deformation. The components of the flow vector, as a function of the orientation g,
can be represented in terms of a series expansion which must obey certain symmetry
conditions. As an example, the flow field calculated according to the Taylor theory for
{111}〈110〉 glide was calculated in 5‐degree steps in the orientation space.
The Misorientation Distribution Function
Authors: Pospiech J. , Sztwiertnia K. , Haessner F.
Published: April 2008

The analysis of misorientations has up to now usually be carried out by comparing the
values obtained experimentally using two dimensional distributions of rotation axes or
rotation angles with the distribution calculated by Mackenzie for the statistically random
case. In this paper the presentation of the distribution of the misorientations is based
on the three dimensional orientation distribution function (ODF) (as described by Bunge).
The new function is termed the misorientation distribution function (MDF) to differentiate
it from the ODF. The advantages in using this function are presented and illustrated
by three MDF′s derived from the work of Haessner, Pospiech and Sztwiertnia.
Anisotropy of Microstructure and Strength in Fiber Textured Molybdenum Alloys
Authors: Oyama T. , Wadsworth J.
Published: April 2008

Molybdenum and molybdenum alloys exhibit brittle behavior in the transverse direction of wrought bar stock despite having good ductility in the longitudinal direction. This is believed to be due to the presence of cracked‐carbide stringers on adversely oriented grain boundaries. In the present paper, the possible role of
anisotropy in strength, as a result of the presence of a strong fiber texture, is investigated. It is concluded, both theoretically and experimentally, that anistropy in strength between the transverse and longitudinal direction of barstock containing a perfect fibre texture is not a factor promoting brittle behavior.
The Effect of Carbon Content on Recrystallisation and Texture Development in Steel
Authors: Ushioda K. , Schlippenbach U. V. , Hutchinson W. B.
Published: April 2008

The effect of differential carbon contents on recrystallisation and texture development has been studied using samples designed to have a known concentration profile. Dissolved carbon can play an active role both at the deformation and annealing stages. Textural changes are associated principally with enhancement of the nucleation rate for recrystallisation with increasing carbon contents. The {111} components become weaker and are replaced by widely scattered orientations. Interstitial carbon present during rolling gives rise to shear banding, causing a
further increase in nucleation rate during recrystallisation and an associated development of the Goss texture.
Creep and Yield Loci of Zircaloy Cladding at Elevated Temperatures
Authors: Murty K. Linga , Kola Ratnaji R. , Mahmood Sheikh T.
Published: April 2008

Crystal plastic models are applied to textured Zircaloy in order to explain the recent experimental results on yield and creep loci by Suzuki et al. Crystallite orientation distribution functions were developed using texture pole figures obtained on cold‐worked stress‐relieved and recrystallized Zircaloy‐4 tubings. The model predictions are in good agreement with experimental loci, and clearly point out the predominance of prism slip contribution for recrystallized material while the contribution of the basal slip increased as the amount of cold work increased.
A New Translational Sample Holder for Reflection Polefigure Measurements
Authors: Welch P. I. , Cronjäger H. A. D. M. , Bunge H. J.
Published: April 2008

A new specimen holder is described which allows true area scanning of circular texture specimens. For large grain sized materials and geological samples this method can lead to a significant increase in the number of grains sampled and thus to more reliable texture measurements. The principle of operation is explained and a prototype apparatus described.
Some Remarks on Theoretical Developments in Quantitative Texture Analysis and on theOptimal Calculation of Harmonic Quantities With High Precision
Authors: Matthies S.
Published: April 2008

After a short characterization of the most important stages of evolution of
quantitative texture analysis as they are seen by the author, problems of simplification
and improvement of precision are discussed especially concerning numerical
calculations using the harmonic apparatus.
Effects of Grain Size on Rollingand Annealing Textures in82%–92% Cold Rolledα‐Brass
Authors: Lee W. B. , Duggan B. J.
Published: April 2008

It is shown that the initial grain size in α‐brass affects rolling texture formation by
the large scale arrangement of developing shear bands, which destroys {111}
oriented material when the grain size is small. This is likely to be a general
phenomenon in low SFE materials. On annealing at 300℃ in the intermediate rolling
reduction range (i.e. 82%–92%), the recrystallisation texture changes from
{236}〈385〉 to {110}〈110〉 with increasing initial grain size. At 600℃ the texture
becomes {110}〈112〉 at grain sizes greater than 200 μm. Nucleation sites of
{110} 〈110〉 crystals have been characterised and conditions favouring the formation
of {110}〈112〉 have been identified.
On the Mechanism of TextureTransition in Face CenteredCubic Metals
Authors: Hu Hsun , Cline R. S.
Published: April 2008

It is shown that, if mechanical twinning and deformation faulting on the {112}〈111〉
orientation of the rolling texture component are prevented or nullified, such as by
cross rolling, the resulting deformation texture is essentially the same for both
high‐SFE (stacking‐fault energy) and low‐SFE metals. These observations are
consistent with the mechanical twinning mechanism for rolling texture transition
from the copper‐type to the brass‐type as proposed by Wassermann.
Texture and Microstructure of Some Low Alloy Steels Containing Nb and B
Authors: Viana C. S. C. , Rios P. R. , Brandão L. P. M.
Published: April 2008

In the present work the textures and the microstructures of some controlled rolled
low carbon steels containing Nb and B were correlated to their boron content. This
varied from 5 to 21 ppm and had the effect of replacing polygonal ferrite in the lower
B‐content steels by bainitic ferrite in the higher B‐content ones. The grain size
decreased from ~3 μm in the former to 1 μm in the latter. The texture became
correspondingly stronger as the transformation mechanism changed from diffusional
to shear mode. Considering that the rolling schedule and cooling rate (air) were the
same for all steels the textural and microstructural changes are attributed to the
change in boron content.
Texture Analysis by TOFMeasurements of SpallationNeutrons With a 2D‐PositionSensitive Detector
Authors: Wenk Hans-Rudolf , Vergamini Phillip J. , Larson Allen C.
Published: April 2008

A new method is introduced to measure preferred crystallographic orientation in
deformed polycrystals. A pulsed beam of protons is accelerated in the linear
accelerator at Los Alamos. The beam is then compressed in time in a storage ring
and directed towards a W spallation target producing bursts of pulsed neutrons of
0.25 μs duration. The neutron beam (107 n cm−2s−1) is scattered by the polycrystal
sample and diffractions, including time of flight of neutrons, are recorded on a 2D
detector. This offers both simultaneous coverage of a wide d spectrum (many peaks)
and a large orientation region (pole figure segment). Results on Al polycrystals
obtained with this instrument agree well with pole figures measured by conventional
X‐ray diffraction.
A Comparison of Measuredand Texture‐Estimated Misorientation Distributions in Type 304 Stainless Steel Tubing
Authors: Zhao Junwu , Adams Brent L. , Morris Peter R.
Published: April 2008

The Misorientation Distribution Function (MDF) was measured for commercial
grade seamless 304 stainless steel tubing. Approximately 4000 boundary misorientations
were used in the measurement. The results were compared with a theoretical
MDF derived from the Crystallite Orientation Distribution Function (CODF)
estimated from 1762 individual orientation measurements, and from x‐ray pole‐figure
measurements, assuming grain orientations to be uncorrelated. It is concluded that
the derived MDF can predict some features of the measured MDF but not all
because of the presence of orientation correlations between adjacent grains.
Grain‐Specific Texture Measurements
Authors: Randle Valerie , Ralph Brian
Published: April 2008

In order to obtain the fullest possible picture of the interrelationship between
texture, microstructure and properties it is necessary to collate data on a “microtextural”
(i.e. grain specific) basis, in addition to more conventional macrotexture
measurements. This paper describes two methods for the acquisition of microtextural
data, the electron backscattering diffraction technique in a scanning electron
microscope, and convergent beam electron diffraction in a transmission electron
microscope. The former method is particularly suitable for the collection of large
quantities of data, and examples of its use are included. In addition to an inverse
pole figure presentation of texture, orientation measurements which arise from
contiguous grains may be analysed from the standpoint of the grain misorientation
texture (GMT). From this type of microtextural data the proportion and distribution
of grain boundaries which possess special properties can be obtained. Since it has
recently been recognised that the properties of special boundaries have a significant
influence on the overall properties of the material, the ability to collect and analyse
easily such data in statistically significant quantities represents an extremely powerful
research technique. Finally, a method for computer generation of GMTs, both from
randomly oriented and textured grain aggregates is described and compared with the
experimental case.
Improvement of Yield Locus Calculation From Pole Figures of Zircaloy Tubes
Authors: Matucha K. H. , Wincierz P.
Published: April 2008

Improvement of yield locus calculation, i.e. better fit with experimental results, was
achieved for Zircaloy tubes with deformation and recrystallization textures in
the following way: (1) Replacement of information from {}‐ and (0001)‐pole
figures by identification of preferred orientation parallel to the tube axis in
combination with the basal pole density distribution in the plane between radial and
tangential direction as a function of the tilt angle γi. (2) Calculation of those parts of
the yield locus which are independent of mechanical twinning. For uniaxial tensile
stress parallel to the tube axis the slope m of the yield locus line for prismatic glide is
given by mi = cos2γi. (3) Calculation of yield locus parts depending on mechanical
twinning using experimentally well established ratios of critical resolved shear
stresses for prismatic slip and several twinning systems.

Mechanical twinning on {}‐planes was confirmed by texture analysis of
plastically deformed tubes after yield locus investigation.
Influence of Texture ona(sin2ψ) Curves Obtained From a Cold Rolled Nickel Sheet using Synchrotron Radiation
Authors: Eckhardt M. , Ruppersberg H.
Published: April 2008

The Two‐Axis Diffractometer at HASYLAB was used to measure a(sin2ψ) curves
by reflecting synchrotron radiation from five different lattice planes of a cold rolled
nickel sheet. We are especially interested in the complex surface state of the
specimen and investigated the sample as delivered without further polishing and
etching. Strongly non‐linear a(sin2ψ) curves were observed. Most of them vary in a
non‐linear way if external uniaxial stress is applied. In this paper we study the
influence of texture using formalism based on the ODF, and evaluated for the Reuss
and the Voigt cases, respectively. Texture alone, however, is not sufficient to explain
the whole variety of the observed effects.
The Evaluation of the Distribution of Residual Stresses of the I. Kind (RS I) and of the II. Kind (RS II) in Textured Materials
Authors: Hauk V. , Nikolin H.-J.
Published: April 2008

Recommendations are given for the type and quantity of X‐ray measurements of
interplanar spacings on different peaks required to evaluate the residual stress (RS)
state within materials having strongly preferred orientations as a result of cold
rolling. The variation of RS I and of RS II with depth from the surface can be
determined by measuring on new surfaces obtained by etching several layers from
both sides of the specimens and by measuring small thin specimens taken from
different parts of the cross‐section. Additional measurements by the etching‐deflection
method show the variation of RS I. Here RS II is understood as the mean
value of the stresses of those crystallites which contribute to the measurement after
subtraction of RS I. The results obtained on a cold rolled thin steel strip show
variation with depth of RS II only.
Neutronographic Fabric Analysis of Quartz in Naturally Deformed Gneiss
Authors: Drechsler L. P. , Feldmann K. , Frischbutter A. , Walther K.
Published: April 2008

The crystalline preferred orientations of quartz grains in pencil gneiss from the
Erzgebirge (southern GDR) are studied by means of neutron time‐of‐flight
diffraction. A single component texture has been found where the trigonal axes are
parallel to the tectonic a‐direction. In the quartz c‐axis pole figure strong maxima at
tectonic ±a are connected by a girdle of weaker intensity being not found in U‐stage
measurements. From the comparison with experimentally deformed quartzites and
model calculations the approximate formation conditions of the given pencil gneiss
could be deduced.
Continuous and DiscreteRepresentations of an IterativeReproduction Method
Authors: Imhof János
Published: April 2008

General formulae are obtained for iterative reproduction of the distribution of
orientations from both unreduced and reduced pole‐figures. The most correct
representation of them is the continuous one realized by the Bunge–Roe formalism.
The discrete representations are always connected with the additional assumption
that the texture function is considered to be constant inside the subsets of orientation
space. One of the discrete representations contains the elements of the elementary
pole‐figures of the vector method.
Developmental and Regional Patterns of GAP-43 Immunoreactivity in a Metamorphosing Brain
Authors: Simmons Andrea Megela , Tanyu Leslie H. , Horowitz Seth S. , Chapman Judith A. , Brown Rebecca A.
Published: April 2008

Growth-associated protein-43 is typically expressed at high levels in the nervous system during development. In adult animals, its expression is lower, but still observable in brain areas showing structural or functional plasticity. We examined patterns of GAP-43 immunoreactivity in the brain of the bullfrog, an animal whose nervous system undergoes considerable reorganization across metamorphic development and retains a strong capacity for plasticity in adulthood. Immunolabeling was mostly diffuse in hatchling tadpoles, but became progressively more discrete as larval development proceeded. In many brain areas, intensity of immunolabel peaked at metamorphic climax, the time of final transition from aquatic to semi-terrestrial life. Changes in intensity of GAP-43 expression in the medial vestibular nucleus, superior olivary nucleus, and torus semicircularis appeared correlated with stage-dependent functional changes in processing auditory stimuli. Immunolabeling in the Purkinje cell layer of the cerebellum and in the cerebellar nucleus was detectable at most developmental time points. Heavy immunolabel was present from early larval stages through the end of climax in the thalamus (ventromedial, anterior, posterior, central nuclei). Immunolabel in the tadpole telencephalon was observed around the lateral ventricles, and in the medial septum and ventral striatum. In postmetamorphic animals, immunoreactivity was confined mainly to the ventricular zones and immediately adjacent cell layers. GAP-43 expression was present in olfactory, auditory and optic cranial nerves throughout larval and postmetamorphic life. The continued expression of GAP-43 in brain nuclei and in cranial nerves throughout development and into adulthood reflects the high regenerative potential of the bullfrog’s central nervous system.
Prediction and Experimental Testing of Ferric Uptake Regulator Regulons in Vibrios
Authors: Ahmad Rafi , Hjerde Erik , Hansen Geir Åsmund , Haugen Peik , Willassen Nils-Peder
Published: April 2008

Iron homeostasis is in many bacteria regulated by the ferric uptake regulator (Fur). Despite the available information on Fur regulons, it is likely that there are Fur-regulated genes and operons that are unique to vibrios, and knowledge into these can potentially provide new insights into vibrio virulence and pathogenesis. We constructed a vibrio-specific alignment matrix based on Fur-binding sites from the literature and used existing software (Patser) to search five published vibrio genomes and the Vibrio salmonicida draft genome for Fur-regulated genes. The consensus Fur-binding site from our matrix is 5′-AATGANAATNATTNTCATT-3′. Fur-binding motifs were found associated with 50–61 single genes and 16–20 operons in each genome. Predictions were tested by monitoring the expression of a subset of genes and operons in V. salmonicida. Six previously undescribed Fur-regulated genes showed increased expression under iron-restrictive conditions. Our work provides a comprehensive list of predicted Fur regulons in six vibrio genomes, which may be used to generate new hypotheses for future experiments.
Diurnal refuge-site selection by Brown Treesnakes (Boiga irregularis) on Guam
Authors: Coupe Brad , Anderson Nancy , Hetherington Thomas , Perry Gad , Williams Joseph
Published: April 2008

Diurnal refuge-site selection was studied in eleven free-ranging brown tree snakes (Boiga irregularis) in tropical forest on the island of Guam. These nocturnal and mostly arboreal snakes were tracked using implanted radio-transmitters. A vegetation survey of the study site was performed to determine if brown treesnakes non-randomly select certain plants for refuge-sites, and thermal profiles of representative refuge sites were obtained with Hobo data loggers. Brown treesnakes preferentially used Pandanus crowns for refuge-sites. Although Pandanus represents a small proportion (3.6%) of the forest, most snakes used Pandanus most of the time for refuge. The thermal characteristics of Pandanus were comparable to those of other refuge-sites. We speculate that features of Pandanus that provide basking opportunities and moist microhabitats may be important for brown treesnakes. As Pandanus is widely distributed throughout the natural range of the brown treesnake, this genus may represent an important refuge-site for this species.
Hydrometeor Detection Using Cloudsat—An Earth-Orbiting 94-GHz Cloud Radar
Authors: Marchand Roger , Mace Gerald G. , Ackerman Thomas , Stephens Graeme
Published: April 2008

In late April 2006, NASA launched Cloudsat, an earth-observing satellite that uses a near-nadir-pointing millimeter-wavelength radar to probe the vertical structure of clouds and precipitation. The first step in using Cloudsat measurements is to distinguish clouds and other hydrometeors from radar noise. In this article the operational Cloudsat hydrometeor detection algorithm is described, difficulties due to surface clutter are discussed, and several examples from the early mission are shown. A preliminary comparison of the Cloudsat hydrometeor detection algorithm with lidar-based results from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite is also provided.
On Deriving Vertical Air Motions from Cloud Radar Doppler Spectra
Authors: Shupe Matthew D. , Kollias Pavlos , Poellot Michael , Eloranta Edwin
Published: April 2008

A method for deriving vertical air motions from cloud radar Doppler spectrum measurements is introduced. The method is applicable to cloud volumes containing small particles, in this case liquid droplets, which are assumed to trace vertical air motions because of their limited size. The presence of liquid droplets is confirmed using multiple ground-based remote sensors. Corrections for Doppler spectrum broadening due to turbulence, wind shear, and radar beamwidth are applied. As a result of the turbulence broadening correction, the turbulent dissipation rate can also be estimated. This retrieval is demonstrated using measurements from the Department of Energy (DOE) Atmospheric Radiation Measurement Program’s (ARM) site in Barrow, Alaska, during the Mixed-Phase Arctic Cloud Experiment (MPACE) of autumn 2004. Comparisons of the retrievals with measurements by research aircraft near Barrow indicate that, on the whole, the retrievals perform well. A small bias in vertical velocity between the retrievals and aircraft measurements is found, based on a statistical comparison of four cases comprising nearly 6 h of data. Turbulent dissipation rate comparisons suggest that the radar-retrieved vertical velocity might be slightly underestimated because of an underestimate of the turbulence broadening correction. However, large uncertainties in aircraft vertical velocity measurements likely impact the comparison.
A New Method for Time Series Filtering near Endpoints
Authors: Arguez Anthony , Yu Peng , O’Brien James J.
Published: April 2008

Time series filtering (e.g., smoothing) can be done in the spectral domain without loss of endpoints. However, filtering is commonly performed in the time domain using convolutions, resulting in lost points near the series endpoints. Multiple incarnations of a least squares minimization approach are developed that retain the endpoint intervals that are normally discarded due to filtering with convolutions in the time domain. The techniques minimize the errors between the predetermined frequency response function (FRF)—a fundamental property of all filters—of interior points with FRFs that are to be determined for each position in the endpoint zone. The least squares techniques are differentiated by their constraints: 1) unconstrained, 2) equal-mean constraint, and 3) an equal-variance constraint. The equal-mean constraint forces the new weights to sum up to the same value as the predetermined weights. The equal-variance constraint forces the new weights to be such that, after convolved with the input values, the expected time series variance is preserved. The three least squares methods are each tested under three separate filtering scenarios [involving Arctic Oscillation (AO), Madden–Julian oscillation (MJO), and El Niño–Southern Oscillation (ENSO) time series] and compared to each other as well as to the spectral filtering method—the standard of comparison. The results indicate that all four methods (including the spectral method) possess skill at determining suitable endpoints estimates. However, both the unconstrained and equal-mean schemes exhibit bias toward zero near the terminal ends due to problems with appropriating variance. The equal-variance method does not show evidence of this attribute and was never the worst performer. The equal-variance method showed great promise in the ENSO project involving a 5-month running mean filter, and performed at least on par with the other realistic methods for almost all time series positions in all three filtering scenarios.
Hurricane Katrina Winds Measured by a Buoy-Mounted Sonic Anemometer
Authors: Howden Stephan , Gilhousen David , Guinasso Norman , Walpert John , Sturgeon Michael , Bender Les
Published: April 2008

The eye of Hurricane Katrina passed within 49 n mi of an oceanographic observing system buoy in the Mississippi Bight that is part of the Central Gulf of Mexico Ocean Observing System. Although a mechanical anemometer failed on the buoy during the hurricane, a two-axis sonic anemometer survived and provided a complete record of the hurricane’s passage. This is the first reported case of a sonic anemometer surviving a hurricane and reporting validated data, and it demonstrates that this type of anemometer is a viable alternative to the mechanical anemometers traditionally used in marine applications. The buoy pitch and roll record during the storm show the importance of compensating the anemometer records for winds oblique to the horizontal plane of the anemometers. This is made apparent in the comparison between the two wind records from the anemometers during the hurricane.
Moist Convection and the Thermal Stratification of the Extratropical Troposphere
Authors: Schneider Tapio , O’Gorman Paul A.
Published: April 2008

Simulations with an aquaplanet general circulation model show that sensible and latent heat transport by large-scale eddies influences the extratropical thermal stratification over a wide range of climates, even in relatively warm climates with small meridional surface temperature gradients. Variations of the lapse rate toward which the parameterized moist convection in the model relaxes atmospheric temperature profiles demonstrate that the convective lapse rate only marginally affects the extratropical thermal stratification in Earth-like and colder climates. In warmer climates, the convective lapse rate does affect the extratropical thermal stratification, but the effect is still smaller than would be expected if moist convection alone controlled the thermal stratification. A theory for how large-scale eddies modify the thermal stratification of dry atmospheres is consistent with the simulation results for colder climates. For warmer and moister climates, however, theories and heuristics that have been proposed to account for the extratropical thermal stratification are not consistent with the simulation results. Theories for the extratropical thermal stratification will generally have to take transport of sensible and latent heat by large-scale eddies into account, but moist convection may only need to be taken into account regionally and in sufficiently warm climates.
A High-Resolution Climate Model for the U.S. Pacific Northwest: Mesoscale Feedbacks and Local Responses to Climate Change*
Authors: Salathé Eric P. , Steed Richard , Mass Clifford F. , Zahn Patrick H.
Published: April 2008

Simulations of future climate scenarios produced with a high-resolution climate model show markedly different trends in temperature and precipitation over the Pacific Northwest than in the global model in which it is nested, apparently because of mesoscale processes not being resolved at coarse resolution. Present-day (1990–99) and future (2020–29, 2045–54, and 2090–99) conditions are simulated at high resolution (15-km grid spacing) using the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5) system and forced by ECHAM5 global simulations. Simulations use the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) A2 emissions scenario, which assumes a rapid increase in greenhouse gas concentrations. The mesoscale simulations produce regional alterations in snow cover, cloudiness, and circulation patterns associated with interactions between the large-scale climate change and the regional topography and land–water contrasts. These changes substantially alter the temperature and precipitation trends over the region relative to the global model result or statistical downscaling. Warming is significantly amplified through snow–albedo feedback in regions where snow cover is lost. Increased onshore flow in the spring reduces the daytime warming along the coast. Precipitation increases in autumn are amplified over topography because of changes in the large-scale circulation and its interaction with the terrain. The robustness of the modeling results is established through comparisons with the observed and simulated seasonal variability and with statistical downscaling results.
A Two-Scale Approximation for Efficient Representation of Nonlinear Energy Transfers in a Wind Wave Spectrum. Part I: Theoretical Development
Authors: Resio Donald T. , Perrie William
Published: April 2008

A new method for estimating the transfer rates in wind wave spectra is derived and tested, based on a two-scale approximation (TSA) to the total integral for quadruplet wave–wave interactions. Comparisons of this new estimation method to the full integral are given for several idealized spectra, including Joint North Sea Wave Project spectra with different peakednesses, a finite depth case, and cases with perturbations added to underlying parametric spectra. In particular, these comparisons show that the TSA is a significant improvement over the discrete interaction approximation (DIA) in deep water and an even greater improvement in shallow water.
Elevation-Dependent Trends in Precipitation Observed during NAME
Authors: Rowe Angela K. , Rutledge Steven A. , Lang Timothy J. , Ciesielski Paul E. , Saleeby Stephen M.
Published: April 2008

Radar data from the 2004 North American Monsoon Experiment (NAME) enhanced observing period were used to investigate diurnal trends and vertical structure of precipitating features relative to local terrain. Two-dimensional composites of reflectivity and rain rate, created from the two Servicio Meteorológico Nacional (SMN; Mexican Weather Service) C-band Doppler radars and NCAR’s S-band polarimetric Doppler radar (S-Pol), were divided into four elevation groups: over water, 0–1000 m (MSL), 1000–2000 m, and greater than 2000 m. Analysis of precipitation frequency and average rainfall intensity using these composites reveals a strong diurnal trend in precipitation similar to that observed by the NAME Event Rain Gauge Network. Precipitation occurs most frequently during the afternoon over the Sierra Madre Occidental (SMO), with the peak frequency moving over the lower elevations by evening. Also, the precipitation events over the lower elevations are less frequent but of greater intensity (rain rate) than those over the SMO. Precipitation echoes were partitioned into convective and stratiform components to allow for examination of vertical characteristics of convection using data from S-Pol. Analyses of reflectivity profiles and echo-top heights confirm that convection over the lower terrain is more intense and vertically developed than convection over the SMO. Warm-cloud depths, estimated from the Colorado State University–NAME upper-air and surface gridded analyses are, on average, 2 times as deep over the lower terrain as compared with over the SMO. Using a simplified stochastic model for drop growth, it is shown that these differences in warm-cloud depths could possibly explain the observed elevation-dependent trends in precipitation intensity.
Diagnosis of an Intense Atmospheric River Impacting the Pacific Northwest: Storm Summary and Offshore Vertical Structure Observed with COSMIC Satellite Retrievals
Authors: Neiman Paul J. , Ralph F. Martin , Wick Gary A. , Kuo Ying-Hwa , Wee Tae-Kwon , Ma Zaizhong , Taylor George H. , Dettinger Michael D.
Published: April 2008

This study uses the new satellite-based Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) mission to retrieve tropospheric profiles of temperature and moisture over the data-sparse eastern Pacific Ocean. The COSMIC retrievals, which employ a global positioning system radio occultation technique combined with “first-guess” information from numerical weather prediction model analyses, are evaluated through the diagnosis of an intense atmospheric river (AR; i.e., a narrow plume of strong water vapor flux) that devastated the Pacific Northwest with flooding rains in early November 2006. A detailed analysis of this AR is presented first using conventional datasets and highlights the fact that ARs are critical contributors to West Coast extreme precipitation and flooding events. Then, the COSMIC evaluation is provided. Offshore composite COSMIC soundings north of, within, and south of this AR exhibited vertical structures that are meteorologically consistent with satellite imagery and global reanalysis fields of this case and with earlier composite dropsonde results from other landfalling ARs. Also, a curtain of 12 offshore COSMIC soundings through the AR yielded cross-sectional thermodynamic and moisture structures that were similarly consistent, including details comparable to earlier aircraft-based dropsonde analyses. The results show that the new COSMIC retrievals, which are global (currently yielding ∼2000 soundings per day), provide high-resolution vertical-profile information beyond that found in the numerical model first-guess fields and can help monitor key lower-tropospheric mesoscale phenomena in data-sparse regions. Hence, COSMIC will likely support a wide array of applications, from physical process studies to data assimilation, numerical weather prediction, and climate research.
Real Time Physically-Based Modeling and Simulation of Cratering and Fragmentation of Terrain
Authors: Rami Nabil , Proctor Michael D.
Published: April 2008

Cratering and fragmentation of terrain due to eXplosions are the behaviors of interest in this effort. We propose a physically-based approach to model the eXplosion event and the process of terrain fragmentation resulting in the formation of craters. Since blast waves are the destructive components of eXplosions, and propagate into materials as stress waves, geology has been introduced into the terrain model. Our methodology is based on voXel modeling and introduces a new method that uses connected fragments to model terrain with the geology. We have used mathematical and visual data from a real eXplosion eXperiment in a layered terrain to validate our model. Using our model, eXplosions can be placed anywhere in the simulation and will result in a realistic output in real time.
Improving Adaptive Importance Sampling Simulation of Markovian Queueing Models using Non-parametric Smoothing
Authors: Woudt Edwin , de Boer Pieter-Tjerk , van Ommeren Jan-Kees
Published: April 2008

Previous work on state-dependent adaptive importance sampling techniques for the simulation of rare events in Markovian queueing models used either no smoothing or a parametric smoothing technique, which was known to be non-optimal. In this paper, we introduce the use of kernel smoothing in this conteXt. We derive eXpressions for the smoothed transition probabilities, compare several variations of the technique, and eXplore the choice of kernel width. We provide some eXamples, demonstrating that the technique significantly improves convergence and estimator variance.
Components of an Incident Management Simulation and Gaming Framework and Related Developments
Authors: Jain Sanjay , McLean Charles R.
Published: April 2008

The nation's emergency responders need to work in a coordinated, well-planned manner to best mitigate the impact of an emergency incident. They need to be trained and ready to act in view of the increased security threat. The training has been traditionally provided using live eXercises at great eXpense. Simulation and gaming systems could provide a wider range of training at a much lower cost. Integrated gaming and simulation systems should be used for training decision makers and responders on the same scenarios, preparing them to work together as a team. A large number of simulation and gaming tools are needed to address the huge number of scenarios that can be of interest for incident management. An efficient approach will be to develop a library of interoperable component models that can be assembled together in different combinations to represent a range of scenarios. Standard specifications of the component models are needed to stimulate the development. The specifications should allow for alternate competing implementations. This paper presents a conceptual architecture that partitions the incident management simulation and gaming solution space into standard components. Recent literature is surveyed to identify related models and/or simulators where available for each defined component. The suggested components and the survey lay some preliminary groundwork in developing a holistic model of the incident response domain.
Risk- and Simulation-Based Optimization of Channel Depths: Entrance Channel of Cam Pha Coal Port
Authors: Quy N.M. , Vrijling J.K. , van Gelder P.H.A.J.M.
Published: April 2008

We present a simulation model for long-term optimal design of channel depths in which the risk of ship grounding due to wave impacts can be assessed for every ship transit. This new model includes four main components: (1) an eXponential probability law for the number of ship departures; (2) a parametric model of the wave-induced ship motions; (3) modeling effects of tidal variations on the channel performance; and (4) a Poisson probability law for the grounding model in a single random ship departure. A key procedure of the simulation process is to define a minimum underkeel clearance allowance for ship entrance and simultaneously determine downtimes that correspond to an acceptable grounding risk for a specified ship and a generated environment condition. The final results derived from the simulation model can be considered as the key parameters in analysis and selection of an optimal depth. The model has been applied to the entrance channel of Cam Pha Coal Port, Vietnam, as a case study.