4,581 research outputs found
Interference effects in f-deformed fields
We show how the introduction of an algeabric field deformation affects the
interference phenomena. We also give a physical interpretation of the developed
theory.Comment: 6 pages, Latex file, no figures, accepted by Physica Script
Algebraic structure of the Green's ansatz and its q-deformed analogue
The algebraic structure of the Green's ansatz is analyzed in such a way that
its generalization to the case of q-deformed para-Bose and para-Fermi operators
is becoming evident. To this end the underlying Lie (super)algebraic properties
of the parastatistics are essentially used.Comment: plain TeX, Preprint INRNE-TH-94/4, 13
Characterizing groundwater flow and heat transport in fractured rock using Fiber-Optic Distributed Temperature Sensing
International audienceWe show how fully distributed space-time measurements with Fiber-Optic Distributed Temperature Sensing (FO-DTS) can be used to investigate groundwater flow and heat transport in fractured media. Heat injection experiments are combined with temperature measurements along fiber-optic cables installed in boreholes. Thermal dilution tests are shown to enable detection of cross-flowing fractures and quantification of the cross flow rate. A cross borehole thermal tracer test is then analyzed to identify fracture zones that are in hydraulic connection between boreholes and to estimate spatially distributed temperature breakthrough in each fracture zone. This provides a significant improvement compared to classical tracer tests, for which concentration data are usually integrated over the whole abstraction borehole. However, despite providing some complementary results, we find that the main contributive fracture for heat transport is different to that for a solute tracer
Schr\"{o}dinger cat state of trapped ions in harmonic and anharmonic oscillator traps
We examine the time evolution of a two level ion interacting with a light
field in harmonic oscillator trap and in a trap with anharmonicities. The
anharmonicities of the trap are quantified in terms of the deformation
parameter characterizing the q-analog of the harmonic oscillator trap.
Initially the ion is prepared in a Schr\"{o}dinger cat state. The entanglement
of the center of mass motional states and the internal degrees of freedom of
the ion results in characteristic collapse and revival pattern. We calculate
numerically the population inversion I(t), quasi-probabilities and
partial mutual quantum entropy S(P), for the system as a function of time.
Interestingly, small deformations of the trap enhance the contrast between
population inversion collapse and revival peaks as compared to the zero
deformation case. For \beta =3 and determines the average number
of trap quanta linked to center of mass motion) the best collapse and revival
sequence is obtained for \tau =0.0047 and \tau =0.004 respectively. For large
values of \tau decoherence sets in accompanied by loss of amplitude of
population inversion and for \tau \sim 0.1 the collapse and revival phenomenon
disappear. Each collapse or revival of population inversion is characterized by
a peak in S(P) versus t plot. During the transition from collapse to revival
and vice-versa we have minimum mutual entropy value that is S(P)=0. Successive
revival peaks show a lowering of the local maximum point indicating a
dissipative irreversible change in the ionic state. Improved definition of
collapse and revival pattern as the anharminicity of the trapping potential
increases is also reflected in the Quasi- probability versus t plots.Comment: Revised version, 16 pages,6 figures. Revte
On the nonlinearity interpretation of q- and f-deformation and some applications
q-oscillators are associated to the simplest non-commutative example of Hopf
algebra and may be considered to be the basic building blocks for the symmetry
algebras of completely integrable theories. They may also be interpreted as a
special type of spectral nonlinearity, which may be generalized to a wider
class of f-oscillator algebras. In the framework of this nonlinear
interpretation, we discuss the structure of the stochastic process associated
to q-deformation, the role of the q-oscillator as a spectrum-generating algebra
for fast growing point spectrum, the deformation of fermion operators in
solid-state models and the charge-dependent mass of excitations in f-deformed
relativistic quantum fields.Comment: 11 pages Late
The quantum superalgebra : deformed para-Bose operators and root of unity representations
We recall the relation between the Lie superalgebra and para-Bose
operators. The quantum superalgebra , defined as usual in terms
of its Chevalley generators, is shown to be isomorphic to an associative
algebra generated by so-called pre-oscillator operators satisfying a number of
relations. From these relations, and the analogue with the non-deformed case,
one can interpret these pre-oscillator operators as deformed para-Bose
operators. Some consequences for (Cartan-Weyl basis,
Poincar\'e-Birkhoff-Witt basis) and its Hopf subalgebra are
pointed out. Finally, using a realization in terms of ``-commuting''
-bosons, we construct an irreducible finite-dimensional unitary Fock
representation of and its decomposition in terms of
representations when is a root of unity.Comment: 15 pages, LaTeX (latex twice), no figure
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Teaching mathematics for search using a tutorial style of delivery
Understanding of mathematics is needed to underpin the process of search, either explicitly with Exact Match (Boolean logic, adjacency) or implicitly with Best match natural language search. In this paper we outline some pedagogical challenges in teaching mathematics for information retrieval (IR) to postgraduate information science students. The aim is to take these challenges either found by experience or in the literature, to identify both theoretical and practical ideas in order to improve the delivery of the material and positively affect the learning of the target audience by using a tutorial style of teaching. Results show that there is evidence to support the notion that a more pro-active style of teaching using tutorials yield benefits both in terms of assessment results and student satisfaction
On the structure of buoyant fires with varying levels of fuel-turbulence
This paper employs a novel burner to study the effects of fuel-generated turbulence on the spatial and temporal structure of buoyant turbulent diffusion flames which are representative of large fires. Fuel-turbulence levels are increased using a perforated plate that issues high-velocity jets, enabling shearing of the fuel stream. The perforated plate may be recessed to control the turbulence level at the jet exit plane. It is shown that the exit plane axial velocity fluctuations can be increased from 0.135 m/s to 1.813 m/s. Varying the levels of fuel-turbulence in the burner allows for the control of key processes defining buoyant fires such as the spatial and temporal flame structure and flame instability modes. These processes are characterised by high-speed simultaneous imaging of planar laser-induced fluorescence of the OH radical (OH-PLIF) and Mie scattering from soot particles. Increasing the fuel-turbulence level deforms the flame, which promotes non-radial lateral entrainment into the flame sheet. This results in a sharp increase in the tilting of the near-field flame sheet along the vertical flame axis. Strong angular entrainment forces are shown to overcome the diffusive and thermal expansive forces at the flame neck, which leads to a strained asymmetric sinuous flame pinch-off instability, followed by separation of the flame base. Sinuous pinch-off instabilities occur at a greater frequency than the symmetric varicose pinch-off instabilities observed for flames with low fuel-turbulence. The asymmetric stretching of the flame neck inhibits the formation of the classical puffing instability formed with an axisymmetric plume that defines classically buoyant flames. Probability density functions calculated for the flame front curvature and flame surface area are shown to monotonically broaden in the near-field region of the flame due to lateral entrainment effects. The transition to buoyancy-driven turbulence also shifts to an increasingly more upstream location. This burner, with its well-defined boundary conditions and novel data, forms a platform for advancing capabilities to model complex fire phenomena including turbulence-buoyancy interactions
Active-distributed temperature sensing to continuously quantify vertical flow in boreholes
We show how a distributed borehole flowmeter can be created from armored Fiber Optic cables with the Active-Distributed Temperature Sensing (A-DTS) method. The principle is that in a flowing fluid, the difference in temperature between a heated and unheated cable is a function of the fluid velocity. We outline the physical basis of the methodology and report on the deployment of a prototype A-DTS flowmeter in a fractured rock aquifer. With this design, an increase in flow velocity from 0.01 to 0.3 m s−1 elicited a 2.5°C cooling effect. It is envisaged that with further development this method will have applications where point measurements of borehole vertical flow do not fully capture combined spatiotemporal dynamics
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