Design and operation of a protection system for transformers with superconducting windings

Power transformers with superconducting windings need a protection system to prevent damage to the low-loss superconducting winding by an abnormally high current. The generally accepted protection technique which uses auxiliary coils has been analysed using a network representation. The current distribution between main and auxiliary coil is expressed in terms of geometrical parameters. Experimental data on current transfer and main coil recovery in a test transformer are presented and a method of obtaining a very low auxiliary coil current is suggested

A superconducting modulator for extremely sensitive voltage measurements across multifilamentary superconducting wires

In this paper we describe a superconducting chopper amplifier used as an instrument to measure the V(I) curve of multifilamentary superconductors. Experimental results are presented

Experimental investigation of the loss characteristics of superconductors for AC power applications

Recent studies confirm the economical feasibility of the application of superconductors in AC power apparatus. The low-loss conductor which has been proposed still only exists in theory. Simple calculations show that the economic criterion described by Ogasawara and Hlásnik is inaccurate because of an oversimplified hysteresis loss formula. A necessary modification shows that stricter demands will have to be made. As production of ultrafine filaments is a big technological problem, final diameter reduction by rolling instead of drawing is proposed. The expected better performance of a rolled composite has been verified experimentally in test coils as well as in transformer geometry. Experimental set-up and results are presented

Beni Atlas': An interface for the informal city

A map is a chart or diagram that uses spatial relationships to communicate information. Through the medium of the map a desired goal can be impressed on people’s minds as a first step to changing the environment. The history of mapping shows that changes in technology brought about ideologies of progress that were communicated in maps. The digital revolution has brought about an image culture that is changing the way we connect with space. Instead of physical rules limiting the way we interact with space, we are now able to redefine it entirely. As architect Richard Wurman writes in the preface of The Exposed City, digital maps allow people “to see the things they’ve always seen but never seen,” and choose to respond to that new knowledge in space. Architects such as Richard Wurman, Buckminster Fuller, James Corner, Ole Bouman, Raoul Bunschoten and MVRDV, to name a few, have acknowledged the need to be involved in the design of digital mapping programs to maintain our position as advocates for quality built space. Digital mapping techniques are considered by many to be a tool of agency for marginalized people in the developing context. The last twenty years have seen a wave of “public participatory GIS (geographic information system)” programs being initiated in communities around the world. Digital maps offer the ability to store and represent an infinite amount of information, make it available to the masses, and apply techniques to make it dynamic and interactive. Beni Atlas explores mapping theory, analyses current employment of digital maps and then employs what is learned to the design for a mapping framework for the community of Beni in the eastern Democratic Republic of Congo in partnership with a local university. The design uses a framework methodology because the image of a map is never alone but is surrounded by a set of community programs and digital sequences that drive how a map is created, used, shared, stored, connected, etc. This framework is the atlas’ (prime) that is taken to a new level of possibility with the use of digital technology. The goal of the framework is to unite data from bottom-up and top down sources, provide clarity and understanding for users, and become a tool that allows for communication and partnership between different actors in the community