4,224 research outputs found
Design of an objective assessment tool to evaluate students' basic electrical engineering skills : the OSTE
This report discusses the developmental stage of a Higher Education Academy (HEA) â Engineering Subject Centre project which concerns the designing of an objective assessment tool to evaluate studentsâ basic electrical engineering skills. The form of assessment is based on the principle of Objective Structured Clinical Examination (OSCE), which is an assessment method already widely adopted in healthcare education. Since it is being used in a different field, this form of OSCE has been named Objective Structured Technical Examination (OSTE). The approach used to develop the exercises included in the OSTE will be discussed. This project will ultimately look at the effectiveness of this method of finding out the basic engineering abilities of a group of students and how it could be used to gear teaching towards any important or specific weaknesses that are discovered among the group.Peer reviewe
Enhancing retinal images by nonlinear registration
Being able to image the human retina in high resolution opens a new era in
many important fields, such as pharmacological research for retinal diseases,
researches in human cognition, nervous system, metabolism and blood stream, to
name a few. In this paper, we propose to share the knowledge acquired in the
fields of optics and imaging in solar astrophysics in order to improve the
retinal imaging at very high spatial resolution in the perspective to perform a
medical diagnosis. The main purpose would be to assist health care
practitioners by enhancing retinal images and detect abnormal features. We
apply a nonlinear registration method using local correlation tracking to
increase the field of view and follow structure evolutions using correlation
techniques borrowed from solar astronomy technique expertise. Another purpose
is to define the tracer of movements after analyzing local correlations to
follow the proper motions of an image from one moment to another, such as
changes in optical flows that would be of high interest in a medical diagnosis.Comment: 21 pages, 7 figures, submitted to Optics Communication
Beyond E11
We study the non-linear realisation of E11 originally proposed by West with
particular emphasis on the issue of linearised gauge invariance. Our analysis
shows even at low levels that the conjectured equations can only be invariant
under local gauge transformations if a certain section condition that has
appeared in a different context in the E11 literature is satisfied. This
section condition also generalises the one known from exceptional field theory.
Even with the section condition, the E11 duality equation for gravity is known
to miss the trace component of the spin connection. We propose an extended
scheme based on an infinite-dimensional Lie superalgebra, called the tensor
hierarchy algebra, that incorporates the section condition and resolves the
above issue. The tensor hierarchy algebra defines a generalised differential
complex, which provides a systematic description of gauge invariance and
Bianchi identities. It furthermore provides an E11 representation for the field
strengths, for which we define a twisted first order self-duality equation
underlying the dynamics.Comment: 97 pages. v2: Minor changes, references added. Published versio
Nonnormal amplification in random balanced neuronal networks
In dynamical models of cortical networks, the recurrent connectivity can
amplify the input given to the network in two distinct ways. One is induced by
the presence of near-critical eigenvalues in the connectivity matrix W,
producing large but slow activity fluctuations along the corresponding
eigenvectors (dynamical slowing). The other relies on W being nonnormal, which
allows the network activity to make large but fast excursions along specific
directions. Here we investigate the tradeoff between nonnormal amplification
and dynamical slowing in the spontaneous activity of large random neuronal
networks composed of excitatory and inhibitory neurons. We use a Schur
decomposition of W to separate the two amplification mechanisms. Assuming
linear stochastic dynamics, we derive an exact expression for the expected
amount of purely nonnormal amplification. We find that amplification is very
limited if dynamical slowing must be kept weak. We conclude that, to achieve
strong transient amplification with little slowing, the connectivity must be
structured. We show that unidirectional connections between neurons of the same
type together with reciprocal connections between neurons of different types,
allow for amplification already in the fast dynamical regime. Finally, our
results also shed light on the differences between balanced networks in which
inhibition exactly cancels excitation, and those where inhibition dominates.Comment: 13 pages, 7 figure
Distance distribution in random graphs and application to networks exploration
We consider the problem of determining the proportion of edges that are
discovered in an Erdos-Renyi graph when one constructs all shortest paths from
a given source node to all other nodes. This problem is equivalent to the one
of determining the proportion of edges connecting nodes that are at identical
distance from the source node. The evolution of this quantity with the
probability of existence of the edges exhibits intriguing oscillatory behavior.
In order to perform our analysis, we introduce a new way of computing the
distribution of distances between nodes. Our method outperforms previous
similar analyses and leads to estimates that coincide remarkably well with
numerical simulations. It allows us to characterize the phase transitions
appearing when the connectivity probability varies.Comment: 12 pages, 8 figures (18 .eps files
La position extérieure de la France à fin 2005.
Lâaugmentation rapide des avoirs et des engagements de la position extĂ©rieure reflĂšte lâinternationalisation de lâĂ©conomie française. LâamĂ©lioration de la position nette rĂ©sulte essentiellement de lâĂ©volution des devises.Position extĂ©rieure, investissements directs, investissements de portefeuille.
A Method for measuring the upper limb motion and computing a compatible exoskeleton trajectory
International audienceThis paper deals with the problem of computing trajectories for an exoskeleton that match a motion recorded on a given subject. Literature suggests that this problem can be solved by reconstructing the subject's joint motion using one of the numerous models available, and then feeding the exoskeleton with the joint trajectories. This is founded on the assumption that the exoskeleton kinematics reproduces the human kinematics. In practice, though, mismatches are unavoidable and lead to inaccuracies. We thus developed a method that is primarily based on an appropriate mechanical design: passive mechanisms are used to connect the exoskeleton with splints wore by the subject, in such a way that, within the workspace, there always exists a posture of the exoskeleton compatible with a given position and orientation of the splints. The trajectory computing method, by itself, consists of recording the position and orientation of the splints thanks to a conventional 3D motion tracker and to exploit standard robotics tools in order to compute an exoskeleton posture compatible with the measured human posture. Conclusive experimental results involving an existing 4 DoF upper-limb exoskeleton are shown
- âŠ