Search results for " Diagnostics"
showing 10 items of 170 documents
Observation of Poincaré-Andronov-Hopf Bifurcation in Cyclotron Maser Emission from a Magnetic Plasma Trap
2018
We report the first experimental evidence of a controlled transition from the generation of periodic bursts of electromagnetic radiation into the continuous-wave regime of a cyclotron maser formed in magnetically confined nonequilibrium plasma. The kinetic cyclotron instability of the extraordinary wave of weakly inhomogeneous magnetized plasma is driven by the anisotropic electron population resulting from electron cyclotron plasma heating in a MHD-stable minimum-B open magnetic trap. peerReviewed
Stark broadening of the hydrogen Paschen ? transition at electron densities of the order of $ \mathsf {10^{15}}$ cm $ \mathsf {^{-3}}$
2003
Stark broadening measurements and calculations of the Paschen γ spectral line of hydrogen ( λ = 1.094[: MU :] m) are reported. Investigations have been performed at plasma electron densities between 1.4×10 15 cm -3 and 3.7×10 15 cm -3 . As the light source a wall-stabilized arc operated in a helium-hydrogen gas mixture at atmospheric pressure has been applied. The radiation of the plasma emitted from nearly homogeneous plasma layers in end-on direction, was measured with the use of a grating spectrometer equipped with a charge coupled device (CCD) detector. The radiance calibration was carried out against light outputs originating from a tungsten strip radiation standard. The measured FWHM …
Experimental investigations of two doubly excited NI multiplets
2005
Experimental Stark-broadening studies of two NI multiplets ( 1 D)3s 2 D - ( 1 D)3p 2 D° and ( 1 D)3s 2 D - ( 1 D) 3 p 2 F° are reported. Measurements were performed using a wall-stabilized arc operated at atmospheric pressure in helium with small amounts of nitrogen and hydrogen. The Stark broadening parameters: the electron impact width (w e ) and shift (d e ) have been determined.
Integrated three-dimensional models for noninvasive monitoring and valorization of the Morgantina silver treasure (Sicily)
2016
The Morgantina silver treasure belonging to the Archaeological Museum of Aidone (Sicily) was involved in a three-dimensional (3-D) survey and diagnostics campaign for monitoring the collection over time in anticipation of their temporary transfer to the Metropolitan Museum of Art in New York for a period of 4 years. Using a multidisciplinary approach, a scientific and methodological protocol based on noninvasive techniques to achieve a complete and integrated knowledge of the precious items and their conservation state, as well as to increase their valorization, has been developed. All acquired data, i.e., 3-D models, ultraviolet fluorescence, x-ray images, and chemical information, will be…
A portable instrument for the location and identification of defects generating PD
2011
A portable instrument based on an antenna probe and suitable for partial discharge detection, have been characterized through both laboratory and on-site experiments carried out on coils and stator windings of ac rotating machines. The antenna probe allows the capture of electromagnetic waves in a bandwidth of 0.1–100 MHz. Pulse signals and ac supply voltage reference are obtained by means of high-pass and low-pass filters, respectively, so avoiding the need of a direct connection with the objects under test. By this way, real-time phase resolved partial discharge patterns can be derived. Results of a comparison of the diagnostic information provided by PD patterns due to conducted and irra…
Performance of the Shape of Partial Discharge Signal Wireless Probes
2013
This paper focuses on the evaluation of the performances of three different antenna sensors suitable of Partial Discharge (PD) measurements. Monopole, triangular and spherical antennas were simulated by means of the surface moment method. The transmitting system is modeled by a power electronic device with a fault current between two metal plate. The shape of the simulated transmitted and received signals have been compared to verify the sensor the provides the best fidelity among the three. The auto-correlation function and the Pearson correlation index are adopted here for the comparison. A discussion on the dynamic characteristic of the different antenna probes and their use in different…
A robust calibration methodology for an On-Board Diagnostic car system
2006
New car models are now by law equipped with on-board diagnostic (OBD) systems aimed at monitoring the state of health of strategic components that ensure low levels of polluting exhaust emissions. During development phases, for each new car model, the OBD system must be finely calibrated. This article presents a robust calibration methodology taking into account sources of variability mainly due to production process, operating, and environmental conditions. The methodology enables us to evaluate the false alarm and failure to detect risks intrinsically related to the adopted calibration. An application concerning an upstream oxygen sensor monitored by the OBD is presented.
An embedded diagnostic system for wheelchairs brushless drives monitoring
2006
The implementation of a microcontroller based monitoring system for the diagnosis of a brushless synchronous motor drives is presented. It finds its primarily interest on motorized wheelchair for disabled people. The embedded system mainly controls all the principal parameters of the electrical drives together with the power supply system. Pre-failure and failure conditions are routinely logged and, depending on the malfunction severity, alarm messages are created and sent to a remote base station by using the GSM wireless network.
Current signature based fault diagnosis of field-oriented and direct torque-controlled induction motor drives
2017
In this article, the operation of three-phase squirrel-cage induction motors is analysed under faulty conditions in closed loop with state-of-the-art controllers, namely, the field-oriented control...
Diagnostic tools for GAMLSS fitted objects
2015
In the last years GAMLSS models were applied in many research fields representing a good solution to analyze data with huge variabilty. In this paper we propose a new approach to diagnostics in GAMLSS as an alternative to classical worm plot. An application will be shown where the class of GAMLSS is applied in order to detect the presence of liver fibrosis as a function of patients risk factors.