1,248 research outputs found
Analysis of defect structure in silicon. Characterization of samples from UCP ingot 5848-13C
Statistically significant quantitative structural imperfection measurements were made on samples from ubiquitous crystalline process (UCP) Ingot 5848 - 13 C. Important trends were noticed between the measured data, cell efficiency, and diffusion length. Grain boundary substructure appears to have an important effect on the conversion efficiency of solar cells from Semix material. Quantitative microscopy measurements give statistically significant information compared to other microanalytical techniques. A surface preparation technique to obtain proper contrast of structural defects suitable for QTM analysis was perfected
G78-396 Making Quality Corn and Sorghum Silage (Revised December 1986)
Harvesting corn and sorghum forage as silage is popular because it adapts to complete mechanization of forage production, harvesting, and feeding. It fits operations where capital can profitably replace labor. If you are going to harvest corn and sorghum forage as silage you need to make quality silage. Here\u27s how
Phase field modeling of electrochemistry II: Kinetics
The kinetic behavior of a phase field model of electrochemistry is explored
for advancing (electrodeposition) and receding (electrodissolution) conditions
in one dimension. We described the equilibrium behavior of this model in [J. E.
Guyer, W. J. Boettinger, J.A. Warren, and G. B. McFadden, ``Phase field
modeling of electrochemistry I: Equilibrium'', cond-mat/0308173]. We examine
the relationship between the parameters of the phase field method and the more
typical parameters of electrochemistry. We demonstrate ohmic conduction in the
electrode and ionic conduction in the electrolyte. We find that, despite making
simple, linear dynamic postulates, we obtain the nonlinear relationship between
current and overpotential predicted by the classical ``Butler-Volmer'' equation
and observed in electrochemical experiments. The charge distribution in the
interfacial double layer changes with the passage of current and, at
sufficiently high currents, we find that the diffusion limited deposition of a
more noble cation leads to alloy deposition with less noble species.Comment: v3: To be published in Phys. Rev. E v2: Attempt to work around
turnpage bug. Replaced color Fig. 4a with grayscale 13 pages, 7 figures in 10
files, REVTeX 4, SIunits.sty, follows cond-mat/030817
Analysis of defect structure in silicon. Characterization of SEMIX material. Silicon sheet growth development for the large area silicon sheet task of the low-cost solar array project
Statistically significant quantitative structural imperfection measurements were made on samples from ubiquitous crystalline process (UCP) Ingot 5848 - 13C. Important correlation was obtained between defect densities, cell efficiency, and diffusion length. Grain boundary substructure displayed a strong influence on the conversion efficiency of solar cells from Semix material. Quantitative microscopy measurements gave statistically significant information compared to other microanalytical techniques. A surface preparation technique to obtain proper contrast of structural defects suitable for quantimet quantitative image analyzer (QTM) analysis was perfected and is used routinely. The relationships between hole mobility and grain boundary density was determined. Mobility was measured using the van der Pauw technique, and grain boundary density was measured using quantitative microscopy technique. Mobility was found to decrease with increasing grain boundary density
Phase field modeling of electrochemistry I: Equilibrium
A diffuse interface (phase field) model for an electrochemical system is
developed. We describe the minimal set of components needed to model an
electrochemical interface and present a variational derivation of the governing
equations. With a simple set of assumptions: mass and volume constraints,
Poisson's equation, ideal solution thermodynamics in the bulk, and a simple
description of the competing energies in the interface, the model captures the
charge separation associated with the equilibrium double layer at the
electrochemical interface. The decay of the electrostatic potential in the
electrolyte agrees with the classical Gouy-Chapman and Debye-H\"uckel theories.
We calculate the surface energy, surface charge, and differential capacitance
as functions of potential and find qualitative agreement between the model and
existing theories and experiments. In particular, the differential capacitance
curves exhibit complex shapes with multiple extrema, as exhibited in many
electrochemical systems.Comment: v3: To be published in Phys. Rev. E v2: Added link to
cond-mat/0308179 in References 13 pages, 6 figures in 15 files, REVTeX 4,
SIUnits.sty. Precedes cond-mat/030817
The Effects Of Increased Responsibility And Its Relationship To General Social Adjustment In Institutionalized Oppositional Retarded Children
The present study tested the hypothesis that giving an institutionalized oppositional retarded child an increase in responsibility would bring about social change in the child in a positive direction
Confirming the Factors of Professional Readiness in Athletic Training
Background: Healthcare professionals such as athletic trainers must be prepared for autonomous practice immediately after graduation. Although certified, new athletic trainers have been shown to have clinical areas of strength and weakness. To better assess professional readiness and improve the preparedness of new athletic trainers, the factors of athletic training professional readiness must be defined. However, limited research exists defining the holistic aspects of professional readiness needed for athletic trainers. Confirming the factors of professional readiness in athletic training could enhance the professional preparation of athletic trainers and result in more highly prepared new professionals. Therefore, the objective of this study was to further explore and confirm the factors of professional readiness in athletic training. Methods: We used a qualitative design based in grounded theory. Participants included athletic trainers with greater than 24 months of experience from a variety of work settings from each district of the National Athletic Trainer’s Association. Participants took the demographic questionnaire electronically using Qualtrics Survey Software (Prove UT). After completing the demographic questionnaire, we selected 20 participants to complete one-on-one interviews using GoToMeeting audiovisual web conferencing software. IMB Statistical Package for the Social Sciences (SPSS, v. 21.0) was used to calculate descriptive statistics for participant demographics. The researcher transcribed all interviews verbatim and a utilized a grounded theory approach during qualitative data analysis. Data were analyzed using a constant comparative analysis as well as open and axial coding. We established trustworthiness by using reflexivity, member checks, and peer reviews. Results: Analysis revealed four overarching themes including management, interpersonal relations, clinical decision-making, and confidence. Conclusion: Athletic trainers should be well-rounded. They must possess communication and organizational skills, the ability to collaborate, value self-reflection and continuing education, and have clinical expertise. Future research should be conducted to finalize a comprehensive model of professional readiness for athletic training, to develop a holistic assessment instrument for athletic training professional readiness, and to explore the preparedness of new athletic trainers as athletic training education transitions to the professional masters degree
Instability of insulating states in optical lattices due to collective phonon excitations
The role of collective phonon excitations on the properties of cold atoms in
optical lattices is investigated. These phonon excitations are collective
excitations, whose appearance is caused by intersite atomic interactions
correlating the atoms, and they do not arise without such interactions. These
collective excitations should not be confused with lattice vibrations produced
by an external force. No such a force is assumed. But the considered phonons
are purely self-organized collective excitations, characterizing atomic
oscillations around lattice sites, due to intersite atomic interactions. It is
shown that these excitations can essentially influence the possibility of atoms
to be localized. The states that would be insulating in the absence of phonon
excitations can become delocalized when these excitations are taken into
account. This concerns long-range as well as local atomic interactions. To
characterize the region of stability, the Lindemann criterion is used.Comment: Latex file, 27 pages, 1 figur
Linear and nonlinear modulus surfaces in stress space, from stress-strain measurements on Berea sandstone
International audienceThe elastic response of many rocks to quasistatic stress changes is highly nonlinear and hysteretic, displaying discrete memory. Rocks also display unusual nonlinear response to dynamic stress changes. A model to describe the elastic behavior of rocks and other consolidated materials is called the Preisach-Mayergoyz (PM) space model. In contrast to the traditional analytic approach to stress-strain, the PM space picture establishes a relationship between the quasistatic data and a number density of hysteretic mesoscopic elastic elements in the rock. The number density allows us to make quantitative predictions of dynamic elastic properties. Using the PM space model, we analyze a complex suite of quasistatic stress-strain data taken on Berea sandstone. We predict a dynamic bulk modulus and a dynamic shear modulus surface as a function of mean stress and shear stress. Our predictions for the dynamic moduli compare favorably to moduli derived from time of flight measurements. We derive a set of nonlinear elastic constants and a set of constants that describe the hysteretic behavior of the sandstone
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