988 research outputs found
The use of an e-learning constructivist solution in workplace learning
We wished to investigate whether an e-learning approach which uses constructivist principles can be successfully applied to train employees in a highly specialised skill thought to require expert individuals and extensive prolonged training. The approach involved the development of an e-learning package which included simulations and interactivity, then experimental testing in a case study workplace environment with the collection of both quantitative and qualitative data to assess the effectiveness of the package. Our study shows that this e-learning strategy improved the skills of the inexperienced
operator significantly. We therefore propose that such programmes could be used as a work based training aid and used as a model system for the training of employees in complex skilled tasks in the workplace. This research demonstrates that the e-learning can be applied outside the traditional learning environment to train unskilled employees to undertake complex practical tasks which traditionally would involve prohibitively expensive instruction. This work also illustrates that simulations and interactivity are powerful tools in the design of successful e-learning packages in preparing learners for real world practical situations. Finally this study shows that workplace learners can be better served by elearning environments rather than conventional training as they allow asynchronous learning and private study which are valued by employees who have other demands on their time and are more comfortable receiving tuition privately Relevance to industry: E-learning using constructivist principles, and incorporating simulations and interactivity can be used successfully in the training of highly specialised and skilled tasks required in the
modern workplace
Generation of Porous Particle Structures using the Void Expansion Method
The newly developed "void expansion method" allows for an efficient
generation of porous packings of spherical particles over a wide range of
volume fractions using the discrete element method. Particles are randomly
placed under addition of much smaller "void-particles". Then, the void-particle
radius is increased repeatedly, thereby rearranging the structural particles
until formation of a dense particle packing.
The structural particles' mean coordination number was used to characterize
the evolving microstructures. At some void radius, a transition from an
initially low to a higher mean coordination number is found, which was used to
characterize the influence of the various simulation parameters. For structural
and void-particle stiffnesses of the same order of magnitude, the transition is
found at constant total volume fraction slightly below the random close packing
limit. For decreasing void-particle stiffness the transition is shifted towards
a smaller void-particle radius and becomes smoother.Comment: 9 pages, 8 figure
Study of Interplanetary Magnetic Field with Ground State Alignment
We demonstrate a new way of studying interplanetary magnetic field -- Ground
State Alignment (GSA). Instead of sending thousands of space probes, GSA allows
magnetic mapping with any ground telescope facilities equipped with
spectropolarimeter. The polarization of spectral lines that are pumped by the
anisotropic radiation from the Sun is influenced by the magnetic realignment,
which happens for magnetic field (<1G). As a result, the linear polarization
becomes an excellent tracer of the embedded magnetic field. The method is
illustrated by our synthetic observations of the Jupiter's Io and comet Halley.
Polarization at each point was constructed according to the local magnetic
field detected by spacecrafts. Both spatial and temporal variations of
turbulent magnetic field can be traced with this technique as well. The
influence of magnetic field on the polarization of scattered light is discussed
in detail. For remote regions like the IBEX ribbons discovered at the boundary
of interstellar medium, GSA provides a unique diagnostics of magnetic field.Comment: 11 pages, 19 figures, published in Astrophysics and Space Scienc
Thermodynamics of a black hole based on a generalized uncertainty principle
We study thermodynamic quantities and the stability of a black hole in a
cavity using the Euclidean action formalism by Gibbons and Hawking based on the
generalized uncertainty relation which is extended in a symmetric way with
respect to the space and momentum without loss of generality. Two parameters in
the uncertainty relation affect the thermodynamical quantities such as energy,
entropy, and the heat capacity. In particular, it can be shown that the small
black hole is unstable and it may decay either into a minimal black hole or a
large black hole. We discuss a constraint for a large black hole comparable to
the size of the cavity in connection with the critical mass.Comment: 12 pages, 4 figures; v2. to appear in JHE
Self-energy and Self-force in the Space-time of a Thick Cosmic String
We calculate the self-energy and self-force for an electrically charged
particle at rest in the background of Gott-Hiscock cosmic string space-time. We
found the general expression for the self-energy which is expressed in terms of
the matrix of the scattering problem. The self-energy continuously falls
down outward from the string's center with maximum at the origin of the string.
The self-force is repulsive for an arbitrary position of the particle. It tends
to zero in the string's center and also far from the string and it has a
maximum value at the string's surface. The plots of the numerical calculations
of the self-energy and self-force are shown.Comment: 15 pages, 4 Postscript figures, ReVTe
The Influence of the Degree of Heterogeneity on the Elastic Properties of Random Sphere Packings
The macroscopic mechanical properties of colloidal particle gels strongly
depend on the local arrangement of the powder particles. Experiments have shown
that more heterogeneous microstructures exhibit up to one order of magnitude
higher elastic properties than their more homogeneous counterparts at equal
volume fraction. In this paper, packings of spherical particles are used as
model structures to computationally investigate the elastic properties of
coagulated particle gels as a function of their degree of heterogeneity. The
discrete element model comprises a linear elastic contact law, particle bonding
and damping. The simulation parameters were calibrated using a homogeneous and
a heterogeneous microstructure originating from earlier Brownian dynamics
simulations. A systematic study of the elastic properties as a function of the
degree of heterogeneity was performed using two sets of microstructures
obtained from Brownian dynamics simulation and from the void expansion method.
Both sets cover a broad and to a large extent overlapping range of degrees of
heterogeneity. The simulations have shown that the elastic properties as a
function of the degree of heterogeneity are independent of the structure
generation algorithm and that the relation between the shear modulus and the
degree of heterogeneity can be well described by a power law. This suggests the
presence of a critical degree of heterogeneity and, therefore, a phase
transition between a phase with finite and one with zero elastic properties.Comment: 8 pages, 6 figures; Granular Matter (published online: 11. February
2012
Mining metrics for buried treasure
The same but different: That might describe two metrics. On the surface
CLASSI may show two metrics are locally equivalent, but buried beneath one may
be a wealth of further structure. This was beautifully described in a paper by
M.A.H. MacCallum in 1998. Here I will illustrate the effect with two flat
metrics -- one describing ordinary Minkowski spacetime and the other describing
a three-parameter family of Gal'tsov-Letelier-Tod spacetimes. I will dig out
the beautiful hidden classical singularity structure of the latter (a structure
first noticed by Tod in 1994) and then show how quantum considerations can
illuminate the riches. I will then discuss how quantum structure can help us
understand classical singularities and metric parameters in a variety of exact
solutions mined from the Exact Solutions book.Comment: 16 pages, no figures, minor grammatical changes, submitted to
Proceedings of the Malcolm@60 Conference (London, July 2004
Possible origins of macroscopic left-right asymmetry in organisms
I consider the microscopic mechanisms by which a particular left-right (L/R)
asymmetry is generated at the organism level from the microscopic handedness of
cytoskeletal molecules. In light of a fundamental symmetry principle, the
typical pattern-formation mechanisms of diffusion plus regulation cannot
implement the "right-hand rule"; at the microscopic level, the cell's
cytoskeleton of chiral filaments seems always to be involved, usually in
collective states driven by polymerization forces or molecular motors. It seems
particularly easy for handedness to emerge in a shear or rotation in the
background of an effectively two-dimensional system, such as the cell membrane
or a layer of cells, as this requires no pre-existing axis apart from the layer
normal. I detail a scenario involving actin/myosin layers in snails and in C.
elegans, and also one about the microtubule layer in plant cells. I also survey
the other examples that I am aware of, such as the emergence of handedness such
as the emergence of handedness in neurons, in eukaryote cell motility, and in
non-flagellated bacteria.Comment: 42 pages, 6 figures, resubmitted to J. Stat. Phys. special issue.
Major rewrite, rearranged sections/subsections, new Fig 3 + 6, new physics in
Sec 2.4 and 3.4.1, added Sec 5 and subsections of Sec
Magnetic Branes in Gauss-Bonnet Gravity
We present two new classes of magnetic brane solutions in
Einstein-Maxwell-Gauss-Bonnet gravity with a negative cosmological constant.
The first class of solutions yields an -dimensional spacetime with a
longitudinal magnetic field generated by a static magnetic brane. We also
generalize this solution to the case of spinning magnetic branes with one or
more rotation parameters. We find that these solutions have no curvature
singularity and no horizons, but have a conic geometry. In these spacetimes,
when all the rotation parameters are zero, the electric field vanishes, and
therefore the brane has no net electric charge. For the spinning brane, when
one or more rotation parameters are non zero, the brane has a net electric
charge which is proportional to the magnitude of the rotation parameter. The
second class of solutions yields a spacetime with an angular magnetic field.
These solutions have no curvature singularity, no horizon, and no conical
singularity. Again we find that the net electric charge of the branes in these
spacetimes is proportional to the magnitude of the velocity of the brane.
Finally, we use the counterterm method in the Gauss-Bonnet gravity and compute
the conserved quantities of these spacetimes.Comment: 17 pages, No figure, The version to be published in Phys. Rev.
Exploration of hyperfine interaction between constituent quarks via eta productions
In this work, the different exchange freedom, one gluon, one pion or
Goldstone boson, in constituent quark model is investigated, which is
responsible to the hyperfine interaction between constituent quarks, via the
combined analysis of the eta production processes,
and . With the Goldstone-boson exchange, as well as
the one-gluon or one-pion exchange, both the spectrum and observables, such as,
the differential cross section and polarized beam asymmetry, are fitted to the
suggested values of Particle Data Group and the experimental data. The first
two types of exchange freedoms give acceptable description of the spectrum and
observables while the one pion exchange can not describe the observables and
spectrum simultaneously, so can be excluded. The experimental data for the two
processes considered here strongly support the mixing angles for two lowest S11
sates and D13 states as about -30 and 6 degree respectively.Comment: 7 pages, 4 figures, 4 table
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