82 research outputs found
Enhancing design learning using groupware
Project work is increasingly used to help engineering students integrate, apply and expand on knowledge gained from theoretical classes in their curriculum and expose students to 'real world' tasks [1]. To help facilitate this process, the department of Design, Manufacture and Engineering Management at the University of Strathclyde has developed a web±based groupware product called LauLima to help students store, share, structure and apply information when they are working in design teams. This paper describes a distributed design project class in which LauLima has been deployed in accordance with a Design Knowledge Framework that describes how design knowledge is generated and acquired in industry, suggesting modes of design teaching and learning. Alterations to the presentation, delivery and format of the class are discussed, and primarily relate to embedding a more rigorous form of project-based learning. The key educational changes introduced to the project were: the linking of information concepts to support the design process; a multidisciplinary team approach to coaching; and a distinction between formal and informal resource collections. The result was a marked improvement in student learning and ideation
Integrable Systems in Stringy Gravity
Static axisymmetric Einstein-Maxwell-Dilaton and stationary axisymmetric
Einstein-Maxwell-Dilaton-Axion (EMDA) theories in four space-time dimensions
are shown to be integrable by means of the inverse scattering transform method.
The proof is based on the coset-space representation of the 4-dim theory in a
space-time admitting a Killing vector field. Hidden symmetry group of the
four-dimensional EMDA theory, unifying T and S string dualities, is shown to be
Sp(2, R) acting transitively on the coset Sp(2, R)/U(2). In the case of
two-parameter Abelian space-time isometry group, the hidden symmetry is the
corresponding infinite-dimensional group of the Geroch-Kinnersley-Chitre type.Comment: 8 pages, LATEX, MSU-DTP-94/21, October 9
Augmenting the 6-3-5 method with design information
This paper describes a comparative study between the 6-3-5 Method and the ICR Grid. The ICR Grid is an evolved variant of 6-3-5 intended to better integrate information into the concept generation process. Unlike a conventional 6-3-5 process where participants continually sketch concepts, using the ICR Grid (the name derived from its Inform, Create, Reflect activities and structured, grid-like output) participants are additionally required to undertake information search tasks, use specific information items for concept development, and reflect on the merit of concepts as the session progresses. The results indicate that although the quantity of concepts was lower, the use of information had a positive effect in a number of areas, principally the quality and variety of output. Although grounded in the area of product development, this research is applicable to any organisation undertaking idea generation and problem solving. As well as providing insights on the transference of information to concepts, it holds additional interest for studies on the composition and use of digital libraries
Ehlers-Harrison transformations and black holes in Dilaton-Axion Gravity with multiple vector fields
Dilaton-axion gravity with vector fields is studied on space-times
admitting a timelike Killing vector field. Three-dimensional sigma-model is
derived in terms of K\"ahler geometry, and holomorphic representation of the
SO(2,2+p) global symmetry is constructed. A general static black hole solution
depending on parameters is obtained via SO(2,2+p) covariantization of
the Schwarzschild solution. The metric in the curvature coordinates looks as
the variable mass Reissner-Nordstr\"om one and generically possesses two
horizons. The inner horizon is pushed to the singularity if electric and
magnetic SO(p) charge vectors are parallel. For non-parallel charges the inner
horizon has a finite area except for an extremal limit when this property is
preserved only for orthogonal charges. Extremal dyon configurations with
orthogonal charges have finite horizon radii continuously varying from zero to
the ADM mass. New general solution is endowed with a NUT parameter, asymptotic
values of dilaton and axion, and a gauge parameter which can be used to ascribe
any given value to one of scalar charges.Comment: 37 pages, Late
3D heterotic string theory: new approach and extremal solutions
We develop a new formalism for the bosonic sector of low-energy heterotic
string theory toroidally compactified to three dimensions. This formalism is
based on the use of some single non-quadratic real matrix potential which
transforms linearly under the action of subgroup of the three-dimensional
charging symmetries. We formulate a new charging symmetry invariant approach
for the symmetry generation and straightforward construction of asymptotically
flat solutions. Finally, using the developed approach and the established
formal analogy between the heterotic and Einstein-Maxwell theories, we
construct a general class of the heterotic string theory extremal solutions of
the Israel-Wilson-Perjes type. This class is asymptotically flat and charging
symmetry complete; it includes the extremal solutions constructed before and
possesses the non-trivial bosonic string theory limit.Comment: 20 pages in Late
The Inverse Scattering Method, Lie-Backlund Transformations and Solitons for Low-energy Effective Field Equations of 5D String Theory
In the framework of the 5D low-energy effective field theory of the heterotic
string with no vector fields excited, we combine two non-linear methods in
order to construct a solitonic field configuration. We first apply the inverse
scattering method on a trivial vacuum solution and obtain an stationary
axisymmetric two-soliton configuration consisting of a massless gravitational
field coupled to a non-trivial chargeless dilaton and to an axion field endowed
with charge. The implementation of this method was done following a scheme
previously proposed by Yurova. We also show that within this scheme, is not
possible to get massive gravitational solitons at all. We then apply a
non-linear Lie-Backlund matrix transformation of Ehlers type on this massless
solution and get a massive rotating axisymmetric gravitational soliton coupled
to axion and dilaton fields endowed with charges. We study as well some
physical properties of the constructed massless and massive solitons and
discuss on the effect of the generalized solution generating technique on the
seed solution and its further generalizations.Comment: 17 pages in latex, changed title, improved text, added reference
Stationary BPS solutions to dilaton-axion gravity
Stationary four-dimensional BPS solutions to gravity coupled bosonic theories
admitting a three-dimensional sigma-model representation on coset spaces are
interpreted as null geodesics of the target manifold equipped with a certain
number of harmonic maps. For asymptotically flat (or Taub-NUT) space-times such
geodesics can be directly parametrized in terms of charges saturating the
Bogomol'nyi-Gibbons-Hull bound, and classified according to the structure of
related coset matrices. We investigate in detail the ``dilaton-axion gravity''
with one vector field, and show that in the space of BPS solutions an classical symmetry is acting. Within the present formalism the
most general multicenter (IWP/Taub-NUT dyon) solutions are derived in a simple
way. We also discover a large new class of asymptotically flat solutions for
which the dilaton and axion charges are constrained only by the BPS bound. The
string metrics for these solutions are generically regular. Both the IWP class
and the new class contain massless solutions.Comment: 29 pages, Latex, no figures. To be published in Phys. Rev. D. Minor
grammatical and bibliographical change
U-Duality and Symplectic Formulation of Dilaton-Axion Gravity
We study a bosonic four--dimensional effective action corresponding to the
heterotic string compactified on a 6--torus (dilaton--axion gravity with one
vector field) on a curved space--time manifold possessing a time--like Killing
vector field. Previously an existence of the global
symmetry (--duality) as well as the symmetric space property of the
corresponding --model have been established following Neugebauer and
Kramer approach. Here we present an explicit form of the generators
in terms of coset variables and construct a representation of the coset in
terms of the physical target space coordinates. Complex symmetric
matrix (``matrix dilaton --axion'') is introduced for which --duality
takes the matrix valued form. In terms of this matrix the theory is
further presented as a K\"ahler --model. This leads to a more concise
formulation which opens new ways to construct exact classical
solutions. New solution (corresponding to constant ) is obtained
which describes the system of point massless magnetic monopoles endowed with
axion charges equal to minus monopole charges. In such a system mutual magnetic
repulsion is exactly balanced by axion attraction so that the resulting space
time is locally flat but possesses multiple Taub--NUT singularities.Comment: LATEX, 20 pages, no figure
Twenty-three unsolved problems in hydrology (UPH) â a community perspective
This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through on-line media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focussed on process-based understanding of hydrological variability and causality at all space and time scales.
Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come
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