996 research outputs found
Amensie en demensie met verwysing na die intellek
,,Es ist der Geist der sich den Kórper baut” het Goethe gesê en hy het daardeur die monistiese begrip in die psigiatrie beklemtoon. Dwarsdeur die eeue het die ontwikkelingsgeskiedenis van die mens maar telkens getoon hoedat daar by die mens veral, nie anders gedink kan word dan as 'n psigosomatiese eenheid nie.
Critical Collapse in Einstein-Gauss-Bonnet Gravity in Five and Six Dimensions
Einstein-Gauss-Bonnet gravity (EGB) provides a natural higher dimensional and
higher order curvature generalization of Einstein gravity. It contains a new,
presumably microscopic, length scale that should affect short distance
properties of the dynamics, such as Choptuik scaling. We present the results of
a numerical analysis in generalized flat slice co-ordinates of self-gravitating
massless scalar spherical collapse in five and six dimensional EGB gravity near
the threshold of black hole formation. Remarkably, the behaviour is universal
(i.e. independent of initial data) but qualitatively different in five and six
dimensions. In five dimensions there is a minimum horizon radius, suggestive of
a first order transition between black hole and dispersive initial data. In six
dimensions no radius gap is evident. Instead, below the GB scale there is a
change in the critical exponent and echoing period.Comment: 21 pages, 39 figures, a couple of references and two new figures
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Development of an Economic Decision Support for the Application of Additive Manufacture in Aerospace
Additive Manufacturing offers a high potential in aerospace industry due to its freedom of
design and the ability to manufacture complex and lightweight parts. The low number of
units, high quality standards and fast response time are special challenges that have to be met
especially in the Maintenance, Repair and Overhaul sector. Thus, companies have to decide at
which point it is economic to apply Additive Manufacturing. However, companies lack
experience on this new technology. This is why a tool is required that takes into account the
above mentioned crucial points and supports the decision process. The paper analyzes
aviation’s characteristics with regard to Additive Manufacturing. The structure of current
MRO repair workflows is investigated to identify a feasible application for Additive
Manufacturing. Additionally the supply chain will be examined to indicate the benefit which
the technology can generate in this highly demanding field. The findings are integrated into a
methodology that supports the decision whether to apply Additive Manufacturing on the basis
of costs, time and quality.Mechanical Engineerin
Quantum Griffiths phase in CePd(1-x)Rh(x) with x ~ 0.8
The magnetic field dependence of the magnetisation () and the temperature
dependence of the ac susceptibility () of CePd(1-x)Rh(x) single
crystals with are analysed within the frame of the
quantum Griffiths phase scenario, which predicts and
with . All vs and
vs data follow the predicted power-law behaviour. The parameter
, extracted from , is very sensitive to the Rh content
and varies systematically with from -0.1 to 0.4. The value of ,
derived from measurements on a \cpr single crystal, seems to be rather
constant, , in a broad range of temperatures between 0.05
and 2 K and fields up to about 10 T. All observed signatures and the
values are thus compatible with the quantum Griffiths scenario.Comment: 4 pages, 3 figure
Huge First-Order Metamagnetic Transition in the Paramagnetic Heavy-Fermion System CeTiGe
We report on the observation of large, step-like anomalies in the
magnetization (\,/Ce), in the magnetostriction
(), and in the magnetoresistance in
polycrystals of the paramagnetic heavy-fermion system CeTiGe at a critical
magnetic field 12.5\,T at low temperatures. The size of
these anomalies is much larger than those reported for the prototypical
heavy-fermion metamagnet CeRuSi. Furthermore, hysteresis between
increasing and decreasing field data indicate a real thermodynamic, first-order
type of phase transition, in contrast to the crossover reported for
CeRuSi. Analysis of the resistivity data shows a pronounced decrease of
the electronic quasiparticle mass across . These results establish CeTiGe
as a new metamagnetic Kondo-lattice system, with an exceptionally large,
metamagnetic transition of first-order type at a moderate field.Comment: 5 pages, 4 figure
Non-Fermi liquid states in the pressurized system: two critical points
In the archetypal strongly correlated electron superconductor CeCuSi
and its Ge-substituted alloys CeCu(SiGe) two quantum
phase transitions -- one magnetic and one of so far unknown origin -- can be
crossed as a function of pressure \cite{Yuan 2003a}. We examine the associated
anomalous normal state by detailed measurements of the low temperature
resistivity () power law exponent . At the lower critical point
(at , ) depends strongly on Ge
concentration and thereby on disorder level, consistent with a
Hlubina-Rice-Rosch scenario of critical scattering off antiferromagnetic
fluctuations. By contrast, is independent of at the upper quantum
phase transition (at , ), suggesting critical
scattering from local or Q=0 modes, in agreement with a density/valence
fluctuation approach.Comment: 4 pages, including 4 figures. New results added. Significant changes
on the text and Fig.
Scanning a photonic crystal slab nanocavity by condensation of xenon
Allowing xenon or nitrogen gas to condense onto a photonic crystal slab nanocavity maintained at 10–20 K results in shifts of the nanocavity mode wavelength by as much as 5 nm (~=4 meV). This occurs in spite of the fact that the mode defect is achieved by omitting three holes to form the spacer. This technique should be useful in changing the detuning between a single quantum dot transition and the nanocavity mode for cavity quantum electrodynamics experiments, such as mapping out a strong coupling anticrossing curve. Compared with temperature scanning, it has a much larger scan range and avoids phonon broadening
Flight Evaluation of an Aircraft with Side and Center Stick Controllers and Rate-Limited Ailerons
As part of an ongoing government and industry effort to study the flying qualities of aircraft with rate-limited control surface actuators, two studies were previously flown to examine an algorithm developed to reduce the tendency for pilot-induced oscillation when rate limiting occurs. This algorithm, when working properly, greatly improved the performance of the aircraft in the first study. In the second study, however, the algorithm did not initially offer as much improvement. The differences between the two studies caused concern. The study detailed in this paper was performed to determine whether the performance of the algorithm was affected by the characteristics of the cockpit controllers. Time delay and flight control system noise were also briefly evaluated. An in-flight simulator, the Calspan Learjet 25, was programmed with a low roll actuator rate limit, and the algorithm was programmed into the flight control system. Side- and center-stick controllers, force and position command signals, a rate-limited feel system, a low-frequency feel system, and a feel system damper were evaluated. The flight program consisted of four flights and 38 evaluations of test configurations. Performance of the algorithm was determined to be unaffected by using side- or center-stick controllers or force or position command signals. The rate-limited feel system performed as well as the rate-limiting algorithm but was disliked by the pilots. The low-frequency feel system and the feel system damper were ineffective. Time delay and noise were determined to degrade the performance of the algorithm
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