Number Of Defect Types Research Articles

Thermodynamic and Kinetic Parameters of the Processes of Deuterium Interaction with Tungsten Protective Coatings

The effect of radiation damage on the retention of deuterium in tungsten (W) was examined. A vacuum-arc plasma source with magnetic stabilization of the cathode spot was used for tungsten coatings preparation. W samples were treated with D ions at temperatures 300‑600 K with a fluence of (1 – 10) ·1020 D2+/m2 and ion energies of 12 keV/D2+. The influence of radiation damage on microstructure and accumulation of deuterium implanted in W samples at room temperature and after annealing have been studied. Thermal desorption (TD) spectroscopy was used to determine the D retained throughout the bulk of the sample. The structure of TD spectra represents the multi-stage process of deuterium release suggesting the trapping of gas atoms by a number of defect types. Computational evaluation of deuterium desorption within the framework of the diffusion-trapping model allows to associate characteristics of experimental TD spectra with specific trapping sites in the material. Experimental TD spectrum was fitted by assigning four binding energies of 0.55 eV, 0.74 eV, 1.09 eV and 1.60 eV for the peaks with maxima at 475, 590, 810 and 1140 K, respectively. The low temperature peak in the TD spectra is associated with desorption of deuterium bounded to the low energy natural traps, whereas the other peaks are related to the desorption of deuterium bounded to the high energy ion induced traps: monovacancies and vacancy clusters.

Identification of Transformer Defects via Analyzing Gases Dissolved in Oil

A description of almost all the current widely used methods used for the interpretation of the results obtained in analyzing gases dissolved in oil (AGDO) is presented. In addition, a new method for identifying defect types, an algorithm for its application, and the advantages thereof over other methods are described. A technique for testing the reliability of the AGDO interpretation methods and results obtained upon testing these methods are presented. The quality of the detection provided by the considered methods has been compared with respect to various types of defects. In the course of the testing, special attention was paid to examining the issue that different methods of AGDO interpretation can identify different number of defect types. The evaluation of the quality of the methods and the testing of their reliability have been performed for a test sample containing 134 cases of transformer damage. For each case, there is a detailed description of the defect development process (the results of analyzing and testing of a transformer for the preceding period and the records in the operational documentation), as well as the results of transformer investigation, in the course of which the cause of damage done to it has been established.

The isochronal annealing of irradiated n-channel power VDMOSFETs

The threshold voltage, VT, as well as threshold voltage shift, ΔVT, and its components, the component of threshold voltage shift due to radiation-induced fixed traps in the oxide, ΔVft, and the component of threshold voltage shift due to radiation-induced switching traps near and at gate oxide/substrate interface, ΔVst, are investigated, and fitted very well. The behavior of unannealed fraction of fixed traps during isochronal annealing is also considered. The proposed model describes unannealed fraction very well, and allows the prediction of fixed traps behavior at higher temperature. The number of defect types that are observably active during an isochronal temperature range could be found by this model, showing that isochronal annealing is competitive with isothermal annealing, which is widely used, but much more time consuming.

Spin glass reflection of the decoding transition for quantum error correcting codes

We study the decoding transition for quantum error correcting codes with the help of a mapping to random-bond Wegner spin models. Families of quantum low density parity-check (LDPC) codes with a finite decoding threshold lead to both known models (e.g., random bond Ising and random plaquette $\Z2$ gauge models) as well as unexplored earlier generally non-local disordered spin models with non-trivial phase diagrams. The decoding transition corresponds to a transition from the ordered phase by proliferation of ``post-topological'' extended defects which generalize the notion of domain walls to non-local spin models. In recently discovered quantum LDPC code families with finite rates the number of distinct classes of such extended defects is exponentially large, corresponding to extensive ground state entropy of these codes. Here, the transition can be driven by the entropy of the extended defects, a mechanism distinct from that in the local spin models where the number of defect types (domain walls) is always finite.

Impact of training standard complexity on inspection performance

Research in the area of visual inspection has shown that various factors influence inspection performance. Task factors have been identified as one of the primary classes of factors influencing the complexity of inspection tasks. If inspection task complexity is to be reduced it is essential to understand the influence of various task factors and prescribe interventions based on the impact of these factors. Moreover, historical work in this area has shown that the greater the difficulty of a vigilance task, the more engaged operators may become. Therefore, this research studies the influence of the following task factors: number of defect types, defect standard complexity, defect probability, and defect distribution on both the visual search and decision-making components of a contact lens inspection task. This study was conducted using a computer simulation of a real world contact lens inspection task using 28 student subjects. Performance was measured on both the visual search and decision-making components of the task. The results revealed a negative influence of defect standard complexity and a positive influence of defect probability on both the visual search and decision-making components of the inspection task. © 2006 Wiley Periodicals, Inc. Hum Factors Man 16: 109–132, 2006.