A deactivated glass capillary, wall-coated open tubular (WCOT) column is the heart of a novel gas chromatographic procedure for measuring reduced sulfur-containing gases in air samples. These deactivated, high resolution WCOT columns provide optimal chromatographic separation of compounds such as H2S, COS, CHgSH, CH3SCH3, CS2, CH3SSCH3, and other organosulfur species. In addition, the combination of WCOT columns, a deactivated GC, and the flame photometric detector (FPD) increases the sensitivity of the GC/FPD method for sulfur compounds. The GC/WCOT/FPD Instrumentation Is also designed for complete compatibility with a cryogenic sampling procedure. This surface-deactivated, cryogenic enrichment system has been shown to provide known sampling efficiencies between 40% to approximately 100% for the important inorganic and organosulfur compounds at the low and sub-ppb concentrations. The methodology described has been successfully applied to field analyses of sulfur compound emissions from biogenic sources.
Railways are the most energy-efficient land-based mode of transport, and electrification is the most energy-efficient way to power the trains. There are many existing solutions to supply the trains with electricity. Regardless of which particular technology is chosen, it is beneficial to interconnect the public power grids to grids supplying power to the railways. This paper shows that the most efficient, flexible, and gentle-for-the-public-grid way of doing that is through powerelectronics-based power converters. Converters offer great benefits regardless of whether the overhead contact lines are of DC-type or AC type, and regardless of the AC grid frequency. This paper presents neither new theory nor new experimental results. Based on already available information, this paper presents logical arguments leading to this conclusion from collected facts. Over time what used to be advanced and high-cost equipment earlier can nowadays be purchased at reasonable cost. It is obvious that for most electrically-fed railways, the use of modern power converters is attractive. Where the individual trains are high consumers of energy, the railway gradients are substantial, and the public grids feeding the railway are weak, the use of converters would be technically desirable, if not necessary for electrification.It is expected that more high-speed railways will be built, and more existing railways will be electrified in the foreseeable future. This paper could provide some insights to infrastructure owners and decision makers in railway administrations about value additions that converter-fed electric railways would provide.
An automatic method for determining the breakdown strength of thin polymer films was evaluated. The equipment consists of a scanning electrode arm with which the breakdown voltage over the film sample is measured. The measurement electrodes were of solid brass and the ground electrode was of thin aluminum foil. Five different electrode areas between 0.045 and 9.3 cm 2 were used and 40-100 individual measurements per electrode area per sample were performed. All measurements were performed in air. The Weibull function parameters α and β were fitted to the obtained data. Different features concerning the measurement system and conditions, e.g. the criteria for the automatic detection of the breakdowns, the effect of the electrode edge design, the DC ramp speed, partial discharges and humidity were analyzed. In order to control the reproducibility of the results, also another type of measurement setup was tested. It was concluded that the measured α-parameter values were stable and repeatable over a period of several years. The average β-parameter values varied ±10-30%, more for the large than the small electrodes, and were also sensitive to changes in the sample, in the measurement conditions and the choice of the electrode system.
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