2,701 research outputs found
Electrodeposition from supercritical fluids
Recent studies have shown that it is possible to electrodeposit a range of materials, such as Cu, Ag and Ge, from various supercritical fluids, including hydrofluorocarbons and mixtures of CO2 with suitable co-solvents. In this perspective we discuss the relatively new field of electrodeposition from supercritical fluids. The perspective focuses on some of the underlying physical chemistry and covers both practical and scientific aspects of electrodeposition from supercritical fluids. We also discuss possible applications for supercritical fluid electrodeposition and suggest some key developments that are required to take the field to the next stage
Collaborative Systems Thinking: Towards an Understanding of Team-level Systems Thinking
As the engineering workforce ages, skills with long development periods are lost with
retiring individuals faster than are younger engineers developing the skills. Systems thinking is
one such skill. Recent research, (Davidz 2006), has shown the importance of experiential
learning in systems thinking skill development. However, an engineering career begun today has
fewer program experiences than in past decades because of extended program lifecycles and a
reduction in the number of new large-scale engineering programs. This pattern is clearly visible
in the aerospace industry, which (Stephens 2003) cites as already experiencing a systems
thinking shortage.
The ongoing research outlined in this paper explores systems thinking as an emergent
property of teams. Collaborative systems thinking, a term coined by the authors to denote teamlevel
systems thinking, may offer an opportunity to leverage and develop a skill in short supply
by concentrating on the team in addition to the individual.
This paper introduces the proposed definition for collaborative systems thinking, as
developed by the authors, and the outlines the structure and progress of ongoing case research
into the role of organizational culture and standard process usage in the development of
collaborative systems thinking
A pearl on SAT solving in Prolog
A succinct SAT solver is presented that exploits the control provided by delay declarations to implement watched literals and unit propagation. Despite its brevity the solver is surprisingly powerful and its elegant use of Prolog constructs is presented as a programming pearl
Adult attachment style across individuals and role-relationships: Avoidance is relationship-specific, but anxiety shows greater generalizability
A generalisability study examined the hypotheses that avoidant attachment, reflecting the representation of others, should be more relationship-specific (vary across relationships more than across individuals), while attachment anxiety, reflecting self-representation, should be more generalisable across a person’s relationships. College students responded to 6-item questionnaire measures of these variables for 5 relationships (mother, father, best same-gender friend, romantic partner or best opposite-gender friend, other close person), on 3 (N = 120) or 2 (N = 77) occasions separated by a few weeks. Results supported the hypotheses, with the person variance component being larger than the relationship-specific component for anxiety, and the opposite happening for avoidance. Anxiety therefore seems not to be as relationship-specific as previous research suggested. Possible reasons for discrepancies between the current and previous studies are discussed
Rush hour-and-a-half: Traffic is spreading out post-lockdown
Traffic congestion is ubiquitous in major cities around the world. Congestion is associated with a slew of negative effects, including delays and local air pollution. Because of the negative effects of congestion, governments invest billions of dollars into the highway system to try to reduce congestion and accommodate peak-hour automobile travel demand. The COVID-19 pandemic presented a significant disruption to transportation systems globally. One impact was a drastic reduction in travel, leading to free-flowing traffic conditions in many previously-congested cities. As lockdowns eased, traffic volumes returned to near-normal levels. However, the temporal pattern of demand may differ, due to increased remote work or other factors. In this article, we examine the temporal distribution of highway demand in California, using data from over 3,500 traffic sensors. We find that peak-hour automobile travel is spreading in the post-lockdown period. In addition to decreased traffic congestion, this finding also has implications for infrastructure investment. Roadways are generally sized based on peak-hour demand. As the peaks spread, some highway construction project may prove unnecessary. It may be possible to reallocate road space to other uses with fewer tradeoffs in terms of traffic congestion
Onsager Relations and Hydrodynamic Balance Equations in 2D Quantum Wells
In this letter we clarify the role of heat flux in the hydrodynamic balance
equations in 2D quantum wells, facilitating the formulation of an Onsager
relation within the framework of this theory. We find that the Onsager relation
is satisfied within the framework of the 2D hydrodynamic balance equation
transport theory at sufficiently high density. The condition of high density is
consonant with the requirement of strong electron-electron interactions for the
validity of our balance equation formulation.Comment: 11 pages, RevTex, 4 postscript figures are avaliable upon reques
Spin tunnelling in mesoscopic systems
We study spin tunnelling in molecular magnets as an instance of a mesoscopic
phenomenon, with special emphasis on the molecule Fe8. We show that the tunnel
splitting between various pairs of Zeeman levels in this molecule oscillates as
a function of applied magnetic field, vanishing completely at special points in
the space of magnetic fields, known as diabolical points. This phenomena is
explained in terms of two approaches, one based on spin-coherent-state path
integrals, and the other on a generalization of the phase integral (or WKB)
method to difference equations. Explicit formulas for the diabolical points are
obtained for a model Hamiltonian.Comment: 13 pages, 5 figures, uses Pramana style files; conference proceedings
articl
Dispersive properties of quasi-phase-matched optical parametric amplifiers
The dispersive properties of non-degenerate optical parametric amplification
in quasi-phase-matched (QPM) nonlinear quadratic crystals with an arbitrary
grating profile are theoretically investigated in the no-pump-depletion limit.
The spectral group delay curve of the amplifier is shown to be univocally
determined by its spectral power gain curve through a Hilbert transform. Such a
constraint has important implications on the propagation of spectrally-narrow
optical pulses through the amplifier. In particular, it is shown that anomalous
transit times, corresponding to superluminal or even negative group velocities,
are possible near local minima of the spectral gain curve. A possible
experimental observation of such effects using a QPM Lithium-Niobate crystal is
suggested.Comment: submitted for publicatio
First normal stress difference and crystallization in a dense sheared granular fluid
The first normal stress difference () and the microstructure
in a dense sheared granular fluid of smooth inelastic hard-disks are probed
using event-driven simulations. While the anisotropy in the second moment of
fluctuation velocity, which is a Burnett-order effect, is known to be the
progenitor of normal stress differences in {\it dilute} granular fluids, we
show here that the collisional anisotropies are responsible for the normal
stress behaviour in the {\it dense} limit. As in the elastic hard-sphere
fluids, remains {\it positive} (if the stress is defined in
the {\it compressive} sense) for dilute and moderately dense flows, but becomes
{\it negative} above a critical density, depending on the restitution
coefficient. This sign-reversal of occurs due to the {\it
microstructural} reorganization of the particles, which can be correlated with
a preferred value of the {\it average} collision angle in the direction opposing the shear. We also report on the shear-induced
{\it crystal}-formation, signalling the onset of fluid-solid coexistence in
dense granular fluids. Different approaches to take into account the normal
stress differences are discussed in the framework of the relaxation-type
rheological models.Comment: 21 pages, 13 figure
Solitary wave solution to the generalized nonlinear Schrodinger equation for dispersive permittivity and permeability
We present a solitary wave solution of the generalized nonlinear Schrodinger
equation for dispersive permittivity and permeability using a scaling
transformation and coupled amplitude-phase formulation. We have considered the
third-order dispersion effect (TOD) into our model and show that soliton shift
may be suppressed in a negative index material by a judicious choice of the TOD
and self-steepening parameter.Comment: 6 page
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