Abstract
The aspects, related to the influence of the electrohydraulic shock method use in a water-cement slurry passing in a closed chamber (activation reactor) with a pre-applied pressure to the ...system under various processing modes are highlighted in the article. In order to test the effect of this method on water-cement slurry, an installation was developed, consisting of: a high-voltage source, a high-voltage diode, capacitor banks, a closing element and an activation reactor. The necessary experiments were carried out on the completed installation. The procedure for conducting experiments is described in the work, shows a schematic diagram of the installation for performing activation, a diagram of the reactor, and the processing modes. Several activation modes were considered, depending on: the number of pulses (1-4), pulse energy (0.5-8 kJ), water-cement ratio (0.2-0.35), time intervals for starting treatment from the moment the cement was mixed with water (0 -120 minutes), volume and shape of the container (activation reactor), holding temperature (20-60°C), etc. According to the results of the data obtained, it was experimentally established that the use of electric pulse treatment of water-cement suspension has a positive effect on strength (cup compressive strength) indicators, obtained as a result of processing cement stone samples at different times of hardening (1-3 days). The compressive strength of the treated specimens’ increases in comparison with the untreated specimens, increase in strength reaches up to 45%, depending on the activation mode. The resulting effect was achieved due to many factors (high pressure, magnetic, temperature, energy, ultrasonic and other influences), which were applied in the most optimal period of time (stage) of the cement grain hydration process.
Development of Micromegas detectors with resistive anode pads Chefdeville, M.; de Oliveira, R.; Drancourt, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2021, Letnik:
1003
Journal Article
Recenzirano
Odprti dostop
A novel type of resistive Micromegas combining a Bulk mesh and a resistive pad board is presented. Readout pads are covered by a thin insulating layer with a top resistive coating segmented into ...resistive pads. Readout and resistive pads are electrically connected by means of planar resistors embedded in the insulator, enabling fast clearance of the avalanche charge from the resistive surface. The maximum gas gain achieved by these resistive detectors is similar to that of non-resistive Micromegas. A possible saturation of the gain for large energy deposits in the gas was investigated by means of 55Fe quanta and electromagnetic showers in the 30–200GeV energy range, but no significant deviation from a proportional response was found. With a suitable choice of the resistance, these detectors demonstrate negligible gain drop and no sparking up to X-ray fluxes of ∼1MHz/mm2 which constitutes a major improvement over non-resistive Micromegas. Spark suppression was also verified in a hadron beam for prototypes with a pad resistance as low as 40kΩ or above. Passive protections of the front-end electronics against sparks (diodes on a printed circuit board) are therefore not required for these resistive detectors.
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