12,094 research outputs found
Collection and dissemination of TES system information for the paper and pulp industry
A survey of U.S. and international paper and pulp mills using thermal energy storage (TES) systems as a part of their production processes was conducted to obtain sufficient operating data to conduct a benefits analysis encompassing: (1) an energy conservation assessment, (2) an economic benefits analysis, and (3) an environmental impact assessment. An information dissemination plan was then proposed to effectively present the benefits of TES to the U.S. paper and pulp industry
Effect of viscosity on rolling-element fatigue life at cryogenic temperature with fluorinated ether lubricants
Rolling-element fatigue tests were conducted with 12.7-mm-(1/2-in.-) diameter AISI 52100 steel balls in the NASA five-ball fatigue tester, with a maximum hertz stress of 5500 mN/m2 (800 000 psi), a shaft speed of 4750 rpm, lubricant temperature of 200 K (360 R), a contact angle of 20 deg, using four fluorinated ether lubricants of varying viscosities. No statistically significant differences in rolling-element fatigue life occurred using the four viscosity levels. Elastohydrodynamic calculations indicate that values of the lubricant film parameter were approximately 2 or greater
Entangled photon apparatus for the undergraduate laboratory
We present detailed instructions for constructing and operating an apparatus
to produce and detect polarization-entangled photons. The source operates by
type-I spontaneous parametric downconversion in a two-crystal geometry. Photons
are detected in coincidence by single-photon counting modules and show strong
angular and polarization correlations. We observe more than 100 entangled
photon pairs per second. A test of a Bell inequality can be performed in an
afternoon.Comment: 6 pages, 9 figure
Self-propulsion of a catalytically active particle near a planar wall: from reflection to sliding and hovering
Micron-sized particles moving through solution in response to self-generated
chemical gradients serve as model systems for studying active matter. Their
far-reaching potential applications will require the particles to sense and
respond to their local environment in a robust manner. The self-generated
hydrodynamic and chemical fields, which induce particle motion, probe and are
modified by that very environment, including confining boundaries. Focusing on
a catalytically active Janus particle as a paradigmatic example, we predict
that near a hard planar wall such a particle exhibits several scenarios of
motion: reflection from the wall, motion at a steady-state orientation and
height above the wall, or motionless, steady "hovering." Concerning the steady
states, the height and the orientation are determined both by the proportion of
catalyst coverage and the interactions of the solutes with the different
"faces" of the particle. Accordingly, we propose that a desired behavior can be
selected by tuning these parameters via a judicious design of the particle
surface chemistry
Study of hot hardness characteristics of tool steels
Hardness measurements of tool steel materials in electric furnace at elevated temperatures and low oxygen environment are discussed. Development of equation to predict short term hardness as function of intial room temperature hardness of steel is reported. Types of steel involved in the process are identified
Common bearing material has highest fatigue life at moderate temperature
AISI 52100, a high carbon chromium steel, has the longest fatigue life of eight bearing materials tested. Fatigue lives of the other materials ranged from 7 to 78 percent of the fatigue life of AISI 52100 at a temperature of 340 K (150 F)
Liquid cryogenic lubricant
Fluorinated polyethers are suitable lubricants for rolling-element bearings in cryogenic systems. Lubrication effectiveness is comparable to that of super-refined mineral oil lubricants operating at room temperature
Effective squirmer models for self-phoretic chemically active spherical colloids
Various aspects of self-motility of chemically active colloids in Newtonian
fluids can be captured by simple models for their chemical activity plus a
phoretic slip hydrodynamic boundary condition on their surface. For particles
of simple shapes (e.g., spheres) -- as employed in many experimental studies --
which move at very low Reynolds numbers in an unbounded fluid, such models of
chemically active particles effectively map onto the well studied so-called
hydrodynamic squirmers [S. Michelin and E. Lauga, J. Fluid Mech. \textbf{747},
572 (2014)]. Accordingly, intuitively appealing analogies of
"pusher/puller/neutral" squirmers arise naturally. Within the framework of
self-diffusiophoresis we illustrate the above mentioned mapping and the
corresponding flows in an unbounded fluid for a number of choices of the
activity function (i.e., the spatial distribution and the type of chemical
reactions across the surface of the particle). We use the central collision of
two active particles as a simple, paradigmatic case for demonstrating that in
the presence of other particles or boundaries the behavior of chemically active
colloids may be \textit{qualitatively} different, even in the far field, from
the one exhibited by the corresponding "effective squirmer", obtained from the
mapping in an unbounded fluid. This emphasizes that understanding the
collective behavior and the dynamics under geometrical confinement of
chemically active particles necessarily requires to explicitly account for the
dependence of the hydrodynamic interactions on the distribution of chemical
species resulting from the activity of the particles.Comment: 26 pages, 11 figure
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