Application Of Reverse Voltage Research Articles

Glass separation processing using crack generation by application of reverse voltage to gold / glass anodic joint and gold migration induced

Glass separation processing using crack generation by application of reverse voltage to gold / glass anodic joint and gold migration induced

In-the-field PID related experiences

Potential induced degradation could considerably decrease the performance of photovoltaic systems which operate at high DC voltages. Nonetheless, methodologies for dealing with it in field are not clearly yet defined. This work explains the kinetics of this phenomenon in the field and presents an assessment of its occurrence, detection and prediction in real PV installations. Measurements of the instantaneous operating voltages of the photovoltaic module as a verification routine and predictive maintenance is proposed here as a reasonable and most accurate way of analyzing the actual power losses of the photovoltaic system related to this kind of degradation, as well as detecting and predicting it. Potential induced degradation prevention and recovery have also been carried out by the application of reverse voltage during the night, showing the validity of this technique. A literature review for the PID dynamics of different kinds of photovoltaic cell technologies and development of PID test methodologies and standards is also presented.

Use of multivariate statistical techniques to optimize the simultaneous separation of 13 phenolic compounds from extra-virgin olive oil by capillary electrophoresis

Characterization of phenolic compounds in olive oil has not been achieved as yet, owing to the complexities of their chemical structures and analytical matrix. The aim of this work is to optimize and validate a method for simultaneous separation and quantification of 13 phenolic compounds from extra-virgin olive oil: tyrosol, hydroxytyrosol, oleuropein glycoside, ferrulic acid, p-coumaric acid, cinnamic acid, p-hydroxybenzoic acid, gallic acid, caffeic acid, luteolin, apigenin, vanillic acid and 3,4-dihydroxybenzoic acid. A statistical central composite design, response surface analysis and the simultaneous optimization method of Derringer and Suich were used to separate all the peaks. These multivariate procedures were efficient in determining the optimal separation condition, using five peak-pair resolutions and runtime as responses. The optimized method employed a fused-silica capillary of 50μm i.d.×60cm effective length with extended light path, 50mmolL−1 boric acid electrolyte, 10.2 pH, 25°C, injection of 50mbar for 25s with application of reverse voltage (−30kV for 5s) before setting the running voltage (+30kV) with detection at 210nm and a run time of 12min. Peak resolutions are found to be very sensitive to pH values outside the 10.15–10.25 range but acceptable electropherograms can be obtained for a wide range of boric acid concentrations within this pH interval.

Effect of Reverse Voltage on Metal/Glass Anodically-Bonded Interface

A voltage in the opposite direction to that of anodic bonding was applied to anodically-bonded joints of Fe and Kovar alloy (Fe-Ni-Co alloy) to borosilicate glass at a temperature at which thermal diffusion of the alkali ions in the glass was activated. Disjunction of the bond interfaces occurred in the Kovar/glass joints. On the other hand, the Fe/glass joints retained cohesion of their bond interface after a long application of reverse voltage. At the bond interface in an as-bonded Kovar/glass joint, a reaction layer of a crystalline Fe oxide formed by the reaction between Fe from Kovar alloy and O from glass. The content of Fe in Kovar alloy adjacent to the bond interface decreased. In an Fe/glass joint the reaction layer of amorphous Fe-Si oxide formed. This layer was much thicker than the reaction layer in the Kovar/glass joint. The Kovar alloy adjacent to the bond interface in the Kovar/glass joint was rich in Ni and Co content. This result suggested that properties of the Kovar/glass bond interface were similar to those of Ni/glass or Co/glass bond interface in some instances. For this reason, effects of reverse voltage on anodically-bonded Ni/glass and Co/glass joints were examined. Disjunction occurred in both joints, and it was suggested that the disjunction of anodically-bonded Kovar/glass interface was caused by alloying elements of Ni and Co.