15,957 research outputs found
Crystal ball, virtual gallery C reation system for immersive environments
This paper presents a concept and a tool suite for authoring, configuring, organizing and displaying 3D virtual galleries, depicting multimedia content, like art, picture, movie or any other kind of media, which are appropriate for large-scale immersive virtual environments such as the CAVE™. A comparison was established by the authors with standard PC environments while experimenting virtual environments produced by Crystal Ball, showing the superior experience obtained by an installation of the type of CAVE™ that is in operation at Lousal, south of Portugal.info:eu-repo/semantics/publishedVersio
Diluted antiferromagnet in a ferromagnetic enviroment
The question of robustness of a network under random ``attacks'' is treated
in the framework of critical phenomena. The persistence of spontaneous
magnetization of a ferromagnetic system to the random inclusion of
antiferromagnetic interactions is investigated. After examing the static
properties of the quenched version (in respect to the random antiferromagnetic
interactions) of the model, the persistence of the magnetization is analysed
also in the annealed approximation, and the difference in the results are
discussed
The detection of lubricating oil viscosity changes in gearbox transmission systems driven by sensorless variable speed drives using electrical supply parameters
Lubrication oil plays a decisive role to maintain a reliable and efficient operation of gear transmissions. Many offline methods have been developed to monitor the quality of lubricating oils. This work focus on developing a novel online method to diagnose oil degradation based on the measurements from power supply system to the gearbox. Experimental studies based on an 10kW industrial gearbox fed by a sensorless variable speed drive (VSD) shows that measurable changes in both static power and dynamic behaviour are different with lube oils tested. Therefore, it is feasible to use the static power feature to indicate viscosity changes at low and moderate operating speeds. In the meantime, the dynamic feature can separate viscosity changes for all different tested cases
Influence of the external pressure on the quantum correlations of molecular magnets
The study of quantum correlations in solid state systems is a large avenue
for research and their detection and manipulation are an actual challenge to
overcome. In this context, we show by using first-principles calculations on
the prototype material KNaCuSiO that the degree of quantum
correlations in this spin cluster system can be managed by external hydrostatic
pressure. Our results open the doors for research in detection and manipulation
of quantum correlations in magnetic systems with promising applications in
quantum information science
Simple computation of ignition voltage of self-sustaining gas discharges
A robust, fast, and accurate numerical method is proposed for finding the voltage of the
ignition of DC self-sustaining gas discharges in a wide range of conditions. The method is
based on physical grounds and builds up from the idea that the ignition of a self-sustaining gas
discharge should be associated with a resonance that would occur in a non-self-sustained
discharge in the same electrode configuration. Examples of the application of the method are
shown for various configurations: parallel-plate discharge, coaxial and wire-to-plane corona
discharges, and a discharge along a dielectric surface. The results conform to the conventional
Townsend breakdown condition for the parallel-plate configuration and are in good agreement
with existing experimental data for the other configurations. The method has the potential of
providing a reference point for optimization of the hold-off capability of high-power
switchgear operating in low-frequency fields.info:eu-repo/semantics/publishedVersio
A practical guide to modeling low-current quasi-stationary gas discharges: Eigenvalue, stationary, and time-dependent solvers
The work is concerned with the modeling of low-current quasi-stationary discharges, including the Townsend and corona discharges. The
aim is to develop an integrated approach suitable for the computation of the whole range of existence of a quasi-stationary discharge from
its inception to a non-stationary transition to another discharge form, such as a transition from the Townsend discharge to a normal glow
discharge or the corona-to-streamer transition. This task includes three steps: (i) modeling of the ignition of a self-sustaining discharge,
(ii) modeling of the quasi-stationary evolution of the discharge with increasing current, and (iii) the determination of the current range
where the quasi-stationary discharge becomes unstable and the non-stationary transition to another discharge form begins. Each of these
three steps is considered in some detail with a number of examples, referring mostly to discharges in high-pressure air.info:eu-repo/semantics/publishedVersio
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