2,128 research outputs found
Relative flattening between velvet and matte 3D shapes: Evidence for similar shape-from-shading computations
No full textAmong other cues, the visual system uses shading to infer the 3D shape of objects. The shading pattern depends on the illumination and reflectance properties (BRDF). In this study, we compared 3D shape perception between identical shapes with different BRDFs. The stimuli were photographed 3D printed random smooth shapes that were either painted matte gray or had a gray velvet layer. We used the gauge figure task (J. J. Koenderink, A. J. van Doorn, & A. M. L. Kappers, 1992) to quantify 3D shape perception. We found that the shape of velvet objects was systematically perceived to be flatter than the matte objects. Furthermore, observers' judgments were more similar for matte shapes than for velvet shapes. Lastly, we compared subjective with veridical reliefs and found large systematic differences: Both matte and velvet shapes were perceived more flat than the actual shape. The isophote pattern of a flattened Lambertian shape resembles the isophote pattern of an unflattened velvet shape. We argue that the visual system uses a similar shape-from-shading computation for matte and velvet objects that partly discounts material propertiesIndustrial Design Engineerin
Wanted dead or alive : high diversity of macroinvertebrates associated with living and ’dead’ Posidonia oceanica matte
No full textThe Mediterranean endemic seagrass Posidonia
oceanica forms beds characterised by a dense leaf canopy
and a thick root-rhizome ‘matte’. Death of P. oceanica
shoots leads to exposure of the underlying matte, which
can persist for many years, and is termed ‘dead’ matte.
Traditionally, dead matte has been regarded as a degraded
habitat. To test whether this assumption was
true, the motile macroinvertebrates of adjacent living
(with shoots) and dead (without shoots) matte of
P. oceanica were sampled in four different plots located
at the same depth (5–6 m) in Mellieha Bay, Malta
(central Mediterranean). The total number of species
and abundance were significantly higher (ANOVA;
P<0.05 and P<0.01, respectively) in the dead matte
than in living P. oceanica matte, despite the presence of
the foliar canopy in the latter. Multivariate analysis
(MDS) clearly showed two main groups of assemblages,
corresponding to the two matte types. The amphipods
Leptocheirus guttatus and Maera grossimana, and the
polychaete Nereis rava contributed most to the dissimilarity
between the two different matte types. Several
unique properties of the dead matte contributing to the
unexpected higher number of species and abundance of
motile macroinvertebrates associated with this habitat
are discussed. The findings have important implications
for the conservation of bare P. oceanica matte, which
has been generally viewed as a habitat of low ecological
value.peer-reviewe
Photograph, R. J. Webb, 1877
No full textThis black and white photograph of Robert J. Webb is set within an arched matte and shows Webb posed wearing a dark suit and tie with a white shirt. His name and Grandview, Texas, is written along the bottom of the matte beneath the photograph. A note indicating that the photograph was taken at Alvarado, Texas on February 20, 1877 is written sideways along the right edge of the matte and For Mother is written on the left edge of the matte.https://scholarsjunction.msstate.edu/mss-webb-collection/1325/thumbnail.jp
William J. Abbott photograph
No full textThis is a tintype of William J. Abbott, who served in Company G of the 36th Ohio Volunteer Infantry (OVI). Company G was recruited from Washington County, Ohio, and Columbiana County, Ohio, and was also known as the "Salem Light Guard."
The matte has the following printed on it: "Field, Artist, 112 W. Fifth St. Cin'ati
Numerical study of plasma-wall transition using an Eulerian Vlasov code
No full textA one-dimensional Eulerian Vlasov code is used to study the self-consistent
solution of a plasma facing a floating collector, in the absence of an
external magnetic field. Both electrons and ions are treated with a kinetic
equation. A Bhatnagar-Gross-Krook (BGK) collision term is used to describe
the collisions. Acceleration of the ion flow at the Debye sheath entrance is
observed together with the formation of a stable steep negative electric
field in front of the floating collector. This negative electric field acts
to accelerate the positive ions towards the plate, pushing back the negative
electrons, such that at steady state the total current collected at the
plate is zero. The codes are run for a sufficiently long time on the ions
time scale to ensure the ions (argon) distribution function is reaching a
steady state. For the different parameters used, the solution shows the
existence of persistent regular oscillations of constant amplitude when the
electron collisions are very small or negligible. These oscillations will be
studied. The increase in the electron collisions damps these oscillations
and helps the system reach an equilibrium
Chromium deportment in copper matte equilibrated with CrxO-containing slag
No full textThesis (MScEng (Process Engineering))--University of Stellenbosch, 2006.An understanding of the behaviour of chromium in mattes equilibrated with
chrome-saturated slags is essential for the prediction and control of chromium
deportment in these melts. The main ore reserves of South Africa’s platinum
group metals (PGM) are associated with the Merensky and UG2 reefs of the
Bushveld Complex. The gradual depletion of the pyroxenitic Merensky reef over
the years has necessitated the PGM industry to exploit the underlying chromiterich
UG2 reef.
The problem with UG2 reef is that it contains significant amounts of chromium,
this being typically 5% (reported as Cr2O3) against <1% for the Merensky reef (in
concentrates). Chromium has a number of deleterious effects on base-metal
smelting processes. Under given conditions, it forms chromite spinels, which can
accumulate and, over a period of time, form undesirable build-ups resulting in
reduced furnace operational volume. The chromite spinels also tend to increase
slag viscosity, thereby impacting negatively on the slag/matte separation, which
leads to matte entrainment in slag. Moreover, high viscosities lead to problems
with tapping of the furnace melts. Finally it can be said that chromium that
deports to the matte during smelting will normally tend to precipitate as spinels
during subsequent converting, and lead to the formation of very stable and
unwanted slag foams in the converter.
In literature, there exists very little published work on the behaviour of
chromium in sulphur-saturated systems such as matte-smelting furnaces. The
few publications that exist in this area do not cover the effect of controlling all
the pertinent variables simultaneously on the behaviour of chromium in mattes
in equilibrium with chromium-containing slags. Hence the main focus of the oxygen fugacities on the mineralogical and deportment behaviour of chromium
in a matte-slag system.
All the three variables (temperature, oxygen fugacity (pO2), and sulphur fugacity
(pS2)) were investigated at three levels. Temperatures studied were 1300°C,
1400°C, and 1500°C. Oxygen and sulphur fugacities were established by
controlling the mix-ratios of purified carbon dioxide, carbon monoxide, sulphur
dioxide, and argon. Oxygen fugacities were maintained at 10-10atm, 10-8atm, and
10-6atm; whereas sulphur fugacities were maintained at 10-6atm, 10-4atm, and 10-
2atm. In order to investigate the effect of each of these three variables
(temperature, pS2, and pO2) at different levels of the other variables, a completely
randomised 33 full factorial experimental design was adopted.
The study revealed that chromium is generally present in matte as both
dissolved CrS and as precipitated oxidic and sulphidic chromium spinel phases.
It was shown that as the conditions become more oxidising (pO2 = 10-6atm), CrS
(which is soluble in matte) becomes a predominant phase, and as the conditions
become more reducing (pO2 = 10-10atm), the sulphospinel, daubreelite (FeCr2S4),
becomes a more predominant phase. Oxidic chromium spinels were found to be
present in matte under the more oxidising conditions (pO2 of 10-6atm) of this
investigation. The presence of the above-mentioned phases was confirmed using
X-ray diffraction.
Subject to the experimental conditions employed in this research, chromium was
found to partition the least to matte under the conditions of; low temperature,
high pO2, and low pS2. Conversely, chromium was found to partition the most to
matte under the conditions of; high temperature, low pO2, and high pS2
Matte volumes for selective data visualization
No full texttechnical reportThe matte volumes system uses a volume renderer, surface renderer, and slice viewer for the exploration and visualization of three-dimensional scalar field data. The size and complexity of the volume data pose an interesting challenge to the ideal of providing the scientist with a system which automatically focuses on regions of interest and accurately visualizes the data from any angle in real time. Matte volumes take a step in the direction by providing the scientist with tools for exploring the data and focusing on regions of interest. Matte volumes are a way of specifying the regions of interest
Spaces and Faces: Namesakes at the University of Arkansas
No full textJ. Vol Walker Hall, which opened in 1935, was originally J. Vol Walker Memorial Library, the main library for campus. The building became home to the Architectural School after the new library was built in 1968. James Volney Walker graduated in 1877 from the University of Arkansas (known at that time as Arkansas Industrial University). He became a prominent lawyer in Northwest Arkansas.Exterior view of the dedication ceremony for Vol Walker Library.Fayettevilleblack and white; matte print; 10" x 8
Spaces and Faces: Namesakes at the University of Arkansas
No full textJ. Vol Walker Hall, which opened in 1935, was originally J. Vol Walker Memorial Library, the main library for campus. The building became home to the Architectural School after the new library was built in 1968. James Volney Walker graduated in 1877 from the University of Arkansas (known at that time as Arkansas Industrial University). He became a prominent lawyer in Northwest Arkansas.Exterior view of the front (east) and north sides of Vol Walker Library.Fayettevilleblack and white; matte print; 10" x 8
Spaces and Faces: Namesakes at the University of Arkansas
No full textJ. Vol Walker Hall, which opened in 1935, was originally J. Vol Walker Memorial Library, the main library for campus. The building became home to the Architectural School after the new library was built in 1968. James Volney Walker graduated in 1877 from the University of Arkansas (known at that time as Arkansas Industrial University). He became a prominent lawyer in Northwest Arkansas.Interior view of main reading room, filled with student, of Vol Walker LibraryFayettevilleblack and white; matte print; 8" x 10
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