OneGeology : improving access to geoscience globally

Contributing scientific solutions to the challenges of landslides and earthquakes, minerals and mining, water supply and flooding, pollution and erosion, and — not least — climate change and energy supply, depends absolutely on geological data. Like most things environmental, few of these challenges respect national or scientific domain frontiers and if we want to assess and address these environmental challenges holistically then we need access to holistic data too. Rich environmental data does exist in each nation, but when it is available, and in many instances it is exceptionally difficult to discover, then it exists in different formats and via different services, with different access conditions. OneGeology is a global initiative to improve the accessibility of one fundamental environmental dataset — geological map data. In addition it is improving the interoperability of those data and the exchange of knowhow and experience. OneGeology has been hugely successful and today 116 nations are participating, with 50 of those nations serving geological data to a dynamic web map portal

The isolation and characterisation of human globin and interferon genes

Imperial Users onl

Demonstration of sustained and useful converter responses during balanced and unbalanced faults in microgrids

In large power grids where converter penetration is presently low and the network impedance is predominantly reactive, the required response from converters during faults is presently specified by phrases such as “maximum reactive output”. However, in marine and aero power systems most faults are unbalanced, the network impedance is resistive, and converter penetration may be high. Therefore a balanced reactive fault current response to an unbalanced fault may lead to over-voltages or over/under frequency events. Instead, this paper presents a method of controlling the converter as a balanced voltage source behind a reactance, thereby emulating the fault response of a synchronous generator (SG) as closely as possible. In this mode there is a risk of converter destruction due to overcurrent. A new way of preventing destruction but still providing fault performance as close to a SG as possible is presented. Demonstrations are presented of simulations and laboratory testing at the 10kVA 400V scale, with balanced and unbalanced faults. Currents can be limited to about 1.5pu while still providing appropriate unbalanced fault response within a resistive network