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See detailHypersensitivity to Electricity: The effect of the current waveform on the perception level
Mattivi, Brice; Beauvois, Véronique ULg; Dular, Patrick ULg et al

in Proceedings of the 4th Int Workshop on Biological Effects of Electromagnetic Fields (2006, October)

Hypersensitivity to electricity has been reported many times in the literature. From another point of view, numerous measurements have been performed on perception level. Even if it appears that part of ... [more ▼]

Hypersensitivity to electricity has been reported many times in the literature. From another point of view, numerous measurements have been performed on perception level. Even if it appears that part of the population has a lower perception level of current, there is no clear link with the so called “hypersensitivity to electricity” which is more related to declared physiological disorders in part of the population (sleeping problem, headache ...). Such declared hypersensitivity is currently not yet related to any biological parameter. Our research team is currently trying to determine a relationship between hypersensitive declared people and the perception level when injecting current in the low frequency range 50-1000 Hz. We have performed current perception tests with individuals under different conditions (different wave shapes, frequencies, influence of external electric field, male and female...) using a particular protocol and our own designed system for current injection. This paper will present our test system design (current injector, wave shape converter, safety aspects) and our first results based on both sine wave (different frequencies) and wide band signal. [less ▲]

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See detailUse of a High-Temperature Superconducting Coil for Magnetic Energy Storage
Fagnard, Jean-François ULg; Crate, David; Jamoye, Jean-François et al

in Institute of Physics Conference Series (2006), 43

A high temperature superconducting magnetic energy storage device (SMES) has been realised using a 350 m-long BSCCO tape wound as a ''pancake'' coil. The coil is mounted on a cryocooler allowing ... [more ▼]

A high temperature superconducting magnetic energy storage device (SMES) has been realised using a 350 m-long BSCCO tape wound as a ''pancake'' coil. The coil is mounted on a cryocooler allowing temperatures down to 17.2 K to be achieved. The temperature dependence of coil electrical resistance R(T) shows a superconducting transition at T = 102.5 K. Measurements of the V(I) characteristics were performed at several temperatures between 17.2 K and 101.5 K to obtain the temperature dependence of the critical current (using a 1 uV/cm criterion). Critical currents were found to exceed 100 A for T < 30 K. An electronic DC-DC converter was built in order to control the energy flow in and out of the superconducting coil. The converter consists of a MOS transistor bridge switching at a 80 kHz frequency and controlled with standard Pulse Width Modulation (PWM) techniques. The system was tested using a 30 V squared wave power supply as bridge input voltage. The coil current, the bridge input and output voltages were recorded simultaneously. Using a 10 A setpoint current in the superconducting coil, the whole system (coil + DC-DC converter) can provide a stable output voltage showing uninterruptible power supply (UPS) capabilities over 1 s. [less ▲]

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See detailSilver paint as a soldering agent for DyBaCuO single-domain welding
Mathieu, Jean-Philippe; Fagnard, Jean-François ULg; Laurent, Philippe ULg et al

in Superconductor Science and Technology (2005), 18(4), 508-512

Silver paint has been tested as a soldering agent for DyBaCuO 4 single-domain welding. Junctions have been manufactured on Dy-Ba-Cu-O single domains cut either along planes parallel to the c-axis IT or ... [more ▼]

Silver paint has been tested as a soldering agent for DyBaCuO 4 single-domain welding. Junctions have been manufactured on Dy-Ba-Cu-O single domains cut either along planes parallel to the c-axis IT or along the ab-planes. Microstructural and superconducting characterizations of the samples have been performed. For both types of junctions, the microstructure in the joined area is very clean: no secondary phase or Ag particle segregation has been observed. Electrical and magnetic measurements for all configurations of interest are reported (rho(T) curves, and Hall probe mapping). The narrow resistive superconducting transition reported for all configurations shows that the artificial junction does not affect significantly the measured superconducting properties of the material. [less ▲]

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See detailInvestigation of DyBa2CU3O7-d superconducting domains grown by the infiltration technique starting with small size Dy-211 particles
Mathieu, Jean-Philippe; Koutzarova, T.; Rulmont, André ULg et al

in Superconductor Science and Technology (2005), 18(2 Sp. Iss. SI), 136-141

An infiltration and growth process is here used as an alternative to the classical top-seeded melt-textured growth process for the production of Dy-123 single-domains with finely dispersed small size Dy ... [more ▼]

An infiltration and growth process is here used as an alternative to the classical top-seeded melt-textured growth process for the production of Dy-123 single-domains with finely dispersed small size Dy-211 particles. The starting materials are the 211-particles and a barium and copper rich liquid phase precursor. The infiltration and growth process allows for controlling both the spatial and size distribution of the 211-particles in the final superconducting 123-single-domain. The main parameters (set-ups, maximum processing temperature with respect to the peritectic temperature, nature of reactant, porosity of the 211-preform) of the infiltration and growth process are discussed. Moreover, different processes of chimie douce are shown in order to produce Dy-211 particles with controlled shape and size, particles that can be used as precursors for the infiltration and growth process. [less ▲]

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See detailStudy by Hall probe mapping of the trapped flux modification produced by local heating in YBCOHTS bulks for different surface/volume ratios
Laurent, Philippe ULg; Mathieu, Jean-Philippe; Mattivi, Brice et al

in Superconductor Science and Technology (2005), 18(8), 1047-1053

The aim of this report is to compare the trapped field distribution under a local heating created at the sample edge for different sample morphologies. Hall probe mappings of the magnetic induction ... [more ▼]

The aim of this report is to compare the trapped field distribution under a local heating created at the sample edge for different sample morphologies. Hall probe mappings of the magnetic induction trapped in YBCO bulk samples maintained out of thermal equilibrium were performed on YBCO bulk single domains, YBCO single domains with regularly spaced hole arrays, and YBCO superconducting foams. The capability of heat draining was quantified by two criteria: the average induction (B) decay and the size of the thermally affected zone caused by a local heating of the sample. Among the three investigated sample shapes, the drilled single domain displays a trapped induction which is weakly affected by the local heating while displaying a high trapped field. Finally, a simple numerical modelling of the heat flux spreading into a drilled sample is used to suggest some design rules about the hole configuration and their size. [less ▲]

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