Penetration of advanced sensor systems such as advanced metering infrastructure (AMI), high-frequency overhead and underground current and voltage sensors have been increasing significantly in power distribution systems over the past few years. According to U.S. energy information administration (EIA), the aggregated AMI installation experienced a 17 times increase from 2007 to 2012. The AMI usually collects electricity usage data every 15 minute, instead of once a month. This is a 3,000 fold increase in the amount of data utilities would have processed in the past. It is estimated that the electricity usage data collected through AMI in the U.S. amount to well above 100 terabytes in 2012. To unleash full value of the complex data sets, innovative big data algorithms need to be developed to transform the way we operate and plan for the distribution system. This paper not only proposes promising applications but also provides an in-depth discussion of technical and regulatory challenges and risks of big data analytics in power distribution systems. In addition, a flexible system architecture design is proposed to handle heterogeneous big data analysis workloads.
A gas-liquid chromatographic (GLC) method is described for determining isosorbide dinitrate (ISDN) in tablets. ISDN is extracted from tablet excipients by a 2-phase system composed of water-ethyl ether, and detected and quantitated with a flame ionization detector after separation from the internal standard (glyceryl tributyrate) on a 3% OV-210 column. Ten replicate assays on 2 different batches of tablets, each containing 5 mg ISDN, gave coefficients of variation of 1.16 and 1.48%, respectively. Comparison of results obtained for tablets containing 5, 10, and 40 mg ISDN, and for diluted isosorbide dinitrate raw material containing 25% ISDN, showed good correlation among the GLC, USP colorimetric, and USP polarographic procedures. Assay of synthetic mixtures containing ISDN, isosorbide-2-mononitrate, and isosorbide-5-mononitrate demonstrated that the GLC procedure is specific for ISDN, whereas the USP polarographic procedure is subject to interference from the mononitrates.
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