ABB Ltd

About: ABB Ltd is a company organization based out in Zurich, Switzerland. It is known for research contribution in the topics: Voltage & Signal. The organization has 6222 authors who have published 6852 publications receiving 83994 citations.

From isotropic to anisotropic superconductors: A scaling approach.

Abstract: We present a new scaling approach which allows one to map results obtained for isotropic superconductors to anisotropic materials in a simple and direct way. The scaling rules are obtained on the level of Ginzburg-Landau-- or London--type equations and applied directly to the desired phenomenological quantity. We illustrate the method by calculating the elasticity moduli, the depinning and melting temperatures, the critical current densities, and the activation barriers for classical and quantum creep in anisotropic superconductors for an arbitrary angle between the magnetic field and the axes of anisotropy.

ClassBench: a packet classification benchmark

Abstract: Packet classification is an enabling technology for next generation network services and often a performance bottleneck in high-performance routers. The performance and capacity of many classification algorithms and devices, including TCAMs, depend upon properties of filter sets and query patterns. Despite the pressing need, no standard performance evaluation tools or filter sets are publicly available. In response to this problem, we present ClassBench, a suite of tools for benchmarking packet classification algorithms and devices. ClassBench includes a filter set generator that produces synthetic filter sets that accurately model the characteristics of real filter sets. Along with varying the size of the filter sets, we provide high-level control over the composition of the filters in the resulting filter set. The tool suite also includes a trace generator that produces a sequence of packet headers to exercise packet classification algorithms with respect to a given filter set. Along with specifying the relative size of the trace, we provide a simple mechanism for controlling locality of reference. While we have already found ClassBench to be very useful in our own research, we seek to eliminate the significant access barriers to realistic test vectors for researchers and initiate a broader discussion to guide the refinement of the tools and codification of a formal benchmarking methodology. (The ClassBench tools are publicly available at the following site: http://www.arl.wustl.edu/~det3/ClassBench/.)

Magnetic properties and AC-losses of superconductors with power law current-voltage characteristics

Abstract: In many high-Tc superconductors the critical current density jc is an ill-defined quantity due to the smooth current—voltage characteristic. Since jc is the basic parameter entering the critical state model, its application to such materials becomes problematic. In this paper, a theory of magnetic properties and AC-losses in superconductors with smooth current—voltage characteristics is proposed. It is applied to superconductors with a power law characteristic, E ≈ jα. The AC-losses are calculated analytically; simple scaling rules are obtained for their dependence on the frequency and the field amplitude. Moreover, it is shown that the normal ohmic conductor and the “perfect” type-II superconductor (critical state) emerge as limiting cases, α = 1 and α = ∞, from the theory.

UV excimer radiation from dielectric-barrier discharges

Abstract: Dielectric-barrier (silent) discharges are ideally suited for efficient excitation of high-intensity UV radiation from excimers. The molecular continuum of xenon at 172 nm could be obtained with an efficiency of close to 10%. Model calculations for excimer formation and UV efficiencies in such discharges are presented. The possibility of obtaining many other wavelengths (e.g. KrF* at 248 nm and XeCl* at 308 nm) and the variety of conceivable geometries (plane or cylindrical) makes this new UV source an attractive choice for many photophysical and photochemical applications.

VSC-HVDC Transmission with Cascaded Two-Level Converters

Abstract: SUMMARY The two-level converter valve together with series-connected press-pack insulated-gate bipolar transistors (IGBTs) is a reliable and proven technology for transmission-scale converters. This has been put to use in a further development of high-voltage dc (HVDC) transmission employing voltage-source converters (VSCs). A cascaded two-level (CTL) converter consisting of several smaller two-level building blocks, also called cells, enables the creation of a nearly sinusoidal output voltage from the converter. The development of the CTL is the subject for this paper. Using technology modules developed and refined during the last 15 years, it has been possible to create a converter that addresses and solves many of the limitations of VSC-HVDC transmission while retaining all operational functionality. The technology is scalable up to the highest transmission voltages. Losses are reduced to roughly 1% per converter through a combination of methods. A method for removing the need for external protective equipment and circuitry in the valves is presented. The main control of the converter has been reused, although the control bandwidth, i.e., the speed, has been further improved.